【Objective】The study aims to investigate the species diversity and biomass spatial patterns of six dominant community types in Yuyao’s ecological welfare forests, and to elucidate the impacts of environmental factors on forest biomass and biodiversity. 【Method】Based on 2020 survey data from 175 sample plots in Yuyao City, Zhejiang Province, this study analyzed tree and shrub layer characteristics including species composition, tree height, DBH (diameter at breast height), basal diameter, and coverage. Combined with stand factors, climatic data, and soil parameters, we systematically examined the spatial distribution patterns of species diversity and biomass across different communities, along with their relationships with environmental variables. 【Result】(1) The total standing biomass of ecological welfare forests in Yuyao reached 6.048 million tons, with an average biomass density of 163.61 t/hm2. (2) Significant spatial heterogeneity in biomass distribution was observed, showing a distinct “north-high, south-low pattern”. Biomass demonstrated significant positive correlations with altitude (P<0.05), latitude (P<0.05), mean tree height (P<0.05), DBH (P<0.05), precipitation(P<0.05), soil nitrogen content (P<0.05), and soil phosphorus content(P<0.05), while exhibiting significant negative correlation with soil bulk density(P<0.05). (3)The Shannon-Wiener diversity index varied significantly among communities (P<0.05), showing the following descending order: broad-leaved forests > coniferous-broadleaved mixed forests > bamboo forests > Chinese fir forests > pine forests > shrublands. The diversity index displayed significant positive correlations with canopy closure (P<0.05), mean DBH (P<0.05), soil nitrogen content(P<0.05), soil organic matter content (P<0.05), and soil moisture content (P<0.05).【Conclusion】The spatial heterogeneity of biomass in major communities of Yuyao’s ecological welfare forests exhibits significant geographical stratification characteristics, with its spatial distribution governed by the integrated effects of multidimensional environmental factors. Specifically, it is primarily driven by the coupling effects of topographic factors (altitude, latitude), stand characteristics (mean DBH, tree height), and soil conditions (soil nitrogen, phosphorus, and bulk density). Community species diversity demonstrates differential responses to environmental gradients: broad-leaved forests maintain the maximum Shannon-Wiener index through synergistic effects between canopy closure and soil fertility (organic matter, moisture content). Precipitation-driven forest biogeochemical processes show significant correlations with community biomass accumulation.
【Objective】Nitrification, a key process in the nitrogen cycle, is closely linked to environmental issues such as N2O emissions, a potent greenhouse gas. Biochar, an emerging soil amendment, has been shown to significantly influence nitrification when added to soil. However, the heterogeneous effects of biochar on nitrification rates and N2O emissions remain unclear, limiting its scientific application in agricultural practices.This study aimed to reveal the spatial variation patterns of the nitrification effect of biochar on global agricultural soil, providing a theoretical basis for optimizing the agricultural environmental benefits of biochar.【Method】This study conducted a meta-analysis on data from 94 published studies and applied machine learning techniques to systematically assess the spatial variability of biochar’s effects on nitrification in global agricultural soils.【Result】The meta-analysis revealed that biochar increased soil nitrification rates by an average of 56% and the abundance of ammonia-oxidizing bacteria (AOB) by 37%. However, it had no significant effect on ammonia-oxidizing archaea (AOA) abundance, suggesting that biochar primarily influences AOB abundance in nitrification. Biochar generally reduced the proportion of N2O emissions as a byproduct of nitrification. Its effects on nitrification, nitrification-induced N2O emissions, and AOB abundance were more pronounced in soils with low buffering capacity (e.g., acidic, low organic carbon, or sandy soils), likely due to its liming effect (increasing soil pH) and structural effect (enhancing soil water and air retention) on soils. Machine learning simulations indicated that biochar had a stronger promoting effect on nitrification rates and associated N2O emissions in tropical regions compared to subtropical and temperate zones. It also had a more significant effect on nitrification and associated N2O emissions in Oxisols, Ultisols, Alfisols, and Mollisols. In contrast, biochar had a relatively minor impact on nitrification rates in Inceptisols, Entisols, Aridisols, and Histosols, and posed a lower risk of increasing N2O emissions in these soils.【Conclusion】Biochar may increase soil nitrification rates and associated N2O emissions especially in low-buffering soils. In practical applications, differentiated application strategies for biochar should be developed based on soil types and climate zone characteristics to achieve the dual goals of soil improvement and green house gas emission reduction.
【Objective】This study explores the trade-offs, synergies, and driving factors among the ecosystem services in Baishanzu National Park, providing support for formulating scientific ecological protection and management strategies.【Method】We quantified four ecosystem services-vegetation net primary productivity (NPP), soil conservation (SC), habitat quality (HQ), and water yield (WY)-in Baishanzu National Park from 2000 to 2020 by using the InVEST and the CASA models. Spearman correlation and geographically weighted regression (GWR) were used to analyze the relationships of trade-offs and synergies among ecosystem services, while the random forest modeling was used to explore the dominant drivers and marginal effects.【Result】From 2000 to 2020, the NPP in Baishanzu National Park nature reserve increased, the HQ declined slightly, and the SC and the WY decreased initially before rising. Spatially, the NPP, the SC, and the WY exhibited similar patterns with high values in central/northwestern regions, whereas the HQ peaked in central/northern areas. The increase in temperature had a significant impact on the relationship between the HQ and the NPP, while precipitation, elevation, and slope had a significant impact on the relationship between the SC and the WY.【Conclusion】The four ecosystem services demonstrated an overall synergy but showed obvious spatial heterogeneity. Climate change was the primary driver of trade-offs/synergies, followed by the degree of vegetation coverage and terrain factors. This indicates that when formulating ecological strategies must therefore account for interactions among these key factors and their potential nonlinear effects.
【Objective】The low hilly region of south China constitutes critical distribution areas for subtropical forests. This study investigates the stoichiometric characteristics of soil carbon, nitrogen, and phosphorus under typical stand types in these regions, as well as their influencing factors, to provide a theoretical foundation for soil fertility assessment and fertilization planning in the southern low hilly regions. 【Method】This study focused on soils from four stand types in the low hilly region of southwestern Zhejiang Province, including Cunninghamia lanceolata forest, Pinus massoniana forest, C. lanceolata and P. massoniama mixed forest, and C. lanceolata and P. edulis mixed forest. We systematically analyzed the response patterns of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) mass fractions, as well as their stoichiometric ratios (C/N, C/P, N/P), to stand type, soil depth, and available nutrients. Additionally, correlations among stoichiometric characteristics and allometric growth relationships between total nutrient mass fractions were investigated. 【Result】(1) In the 0-40 cm soil layer, soil TN and TP mass fraction exhibited statistically significant differences among the four stand types, with mean values of 1.20 and 0.19 g/kg, respectively. Both soil TN and TP reached their highest level in the C. lanceolata and P. edulis mixed forest. The mean values of the ratio of SOC to TN (C/N, mass fraction ratio, the same below) and the ratio of SOC to TP (C/P) in soil were 17.20 and 106.53, respectively. The soil C/N and C/P ratios in the C. lanceolata and P. edulis mixed forest were significantly lower than those in C. lanceolata forest and C. lanceolata and P. massoniama mixed forest. (2) With increasing soil depth, the mass fraction of soil SOC, TN, and TP exhibited a declining trend both in the aggregated dataset and within each individual stand type. In contrast, the soil C/N displayed an upward trend, while the nitrogen-to-phosphorus ratio (N/P) showed declining trend with depth. (3) Correlation analysis demonstrated significant positive correlations between soil SOC, TN, and TP mass fractions, as well as their associated stoichiometric ratios. Additionally, a significant positive correlation was identified between TN and TP mass fractions. Standardized major axis analysis demonstrated that the accumulation rate of soil TP mass fraction was slightly lower than that of TN, while being significantly lower than that of SOC. Redundancy analysis indicated that soil pH exerted a negative regulatory effect on the C/P ratio, while soil hydrolysable nitrogen significantly modulated both the mass fractions of TN and TP and their stoichiometric ratios. 【Conclusion】Stand types in the low hilly region of western Zhejiang have significant effects on soil carbon and nutrient mass fractions and stoichiometric ratios. The C. lanceolata and P. edulis mixed forest may improve soil nutrient status by reducing soil acidification and other apporoaches.
【Objective】This study aimed to investigate the impacts of Elaphurus davidianus disturbance on soil ecological stoichiometry in Yancheng coastal wetlands, assess the current state of soil degradation, and provide a scientific foundation for the sustainable management of the reserve.【Method】The third core area of Yancheng Dafeng Milu National Nature Reserve was selected as the study site. Based on field surveys, the area was stratified into five disturbance intensity levels: weak (Ⅰ), mild (Ⅱ), moderate (Ⅲ), secondary heavy (IV), and severe (V). Soil physicochemical properties, including bulk density (BD), soil water content (WC), pH, the content of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP), were measured through laboratory analyses. The effects of varying disturbance intensities on soil properties and ecological stoichiometric ratios were systematically evaluated. 【Result】(1) With the increase of E. davidianus disturbance intensity, soil BD frist decreased, and then increased, soil pH increased, while soil TN, TP content and soil WC first increased and then decreased, and SOC content showed a fluctuating trend. (2) With the increase of E. davidianus disturbance intensity, the soil C/N (mass ratio) increased, the soil N/P (mass ratio) decreased, and the soil C/P (mass ratio) fluctuated. (3) The correlations between soil C/P and SOC, and between soil N/P and TN were extremely high, and the correlation between C/N and SOC gradually decreased with the increase of E. davidianus disturbance intensity. SOC content was the main limiting factor of soil C/N and C/P, and soil TN content was the main limiting factor of soil N/P. 【Conclusion】E. davidianus disturbance not only changes the basic soil properties and ecological stoichiometric characteristics, but also changes the intensity of soil stoichiometric ratios. Moderate and mild disturbance of E. davidianus is more conducive to soil mineralization and nutrient cycling. These findings suggest that maintaining E. davidianus populations within a reasonable threshold is critical for preserving soil nutrient equilibrium in Yancheng coastal wetlands.
【Objective】This study aimed to clarify the nutrient-use characteristics and physiological adaptation strategies of six commonly used soil and water conservation tree species in a typical black soil region.【Method】From the perspective of biomass allocation, six species were selected: Caragana microphylla, Prunus triloba, Betula platyphylla, Acer saccharinum, Picea koraiensis, and Pinus sylvestris var. mongholica, representing three life forms (evergreen arbors, deciduous shrubs, and deciduous trees). Mass fractions of carbon (C), nitrogen (N), and phosphorus (P) were measured in leaves, bark, branches, stems, fine roots, and coarse roots. Stoichiometric ratios (C/N, C/P, N/P) were calculated, and correlation analyses and allometric models were applied to examine relationships among element concentrations and their accumulation rates across organs.【Result】Carbon mass fractions exhibited greater stability than N and P; for deciduous species, belowground carbon stability exceeded that of aboveground parts. Nitrogen stability was consistently higher aboveground than belowground across all life forms, while the coefficient of variation for P was highest in shrub leaves. Total C mass fraction was greater in aboveground than belowground organs, whereas both N and P followed the same allocation strategy, with fine-root concentrations exceeding those in coarse roots. In tree species, C and N concentrations were positively correlated (P < 0.05), while C-P correlations were not significant; in shrub species, C correlated very significantly negatively with N (P < 0.01) and significantly negatively with P (P < 0.05). Significant allometric relationships were found for C-N and C-P across organs, with C accumulation rates generally lower than those of N and P. In contrast, N-P allometries varied by life form: evergreen arbors showed isometric growth between N and P in all organs except bark and fine roots; deciduous shrubs exhibited isometry only in leaves; deciduous trees displayed isometric N-P relationships across all six organs, with N accumulation rates consistently lower than those of P, while in stems and coarse roots of deciduous shrubs and across organs of deciduous trees, N accumulation rates were close to those of P. 【Conclusion】Nutrient uptake and utilization across plant organs are coordinated and tightly coupled, but the physiological metabolism of limiting elements N and P differ among seedlings of different life forms. Species-specific traits give rise to distinct nutrient-allocation patterns and stoichiometric characteristics. These findings provide a theoretical basis for the scientific cultivation of soil and water conservation species and the establishment of conservation forests in the typical black soil region of China.
【Objective】The increasing frequency of global drought events has significantly affected the structure and function of forest ecosystems. This study aims to estimate the effects of drought on contents of particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) at different soil depths in poplar plantation, providing a theoretical basis for predicting the responses of forest soil organic carbon (SOC) and its stability to drought in the future.【Method】We took a 10-year-old poplar plantation in Dongtai Forest Farm, Jiangsu Province as the research object. In August 2018, three drought treatments for reducing throughfall were set up: i.e., a control treatment (CK), a moderate drought with reduced 30% throughfall (D30%), and a severe drought with reduced 50% throughfall (D50%). Three replicate sample plots were set up for each treatment with a total of nine sample plots. After four consecutive years of field controll experiments, soil samples were collected in July and November 2022, and February and April 2023 in each drought-treated sample plot to determine soil POC and MAOC contents in the growing (July 2022) and non-growing (February 2023) seasons, as well as soil physicochemical properties such as SOC, dissolved organic carbon, microbial biomass carbon, and readily oxidizable organic carbon in these four periods. Based on ANOVA, correlation analysis, and redundancy analysis, we quantified the characteristics of changes in soil POC and MAOC under drought stress and analyzed the key factors driving the variation in their contents.【Result】Drought had no significant effect on soil POC content, while its impact on soil MAOC content was constrained by season, drought degree and soil depth. Specifically, during the growing season, moderate drought (D30%) significantly increased the MAOC content in the surface soil [0,10)cm, while both drought treatments (D30% and D50%) significantly decreased the MAOC content in the middle soil layer ([10,20)cm) and lower soil layers ([20,40) cm). During the non-growing season, both drought treatments (D30% and D50%) significantly reduced the MAOC content in the surface soil, but had no significant effect on the middle and lower soil layers. Vertically, the soil POC and MAOC content decreased significantly with soil depth. The correlation results showed that POC and MAOC content were significantly and positively correlated with most soil physical and chemical properties, while were significantly and negatively correlated with bulk density and carbon to nitrogen ratio(C/N). Redundancy analysis indicated that soil microbial biomass carbon was the key factor driving the dynamic changes of soil POC and MAOC content under drought.【Conclusion】Drought had no significant effect on soil POC content in the poplar plantation; however, it significantly altered soil MAOC contents, and the effect was constrained by factors such as season, drought degree, and soil depth. This study suggests that when predicting the response of forest soil carbon pool stability to drought in the future, factors such as season, drought degree and soil depth should be fully considered.
【Objective】This research aims to investigate the characteristics of phosphorus forms in soil aggregates, iron oxids and the distribution of phosphate-solubilising bacteria in different forest types, and to reveal the relationship between phosphorus forms and forest type transition, so as to provide a reference for the understanding of the influence mechanism of soil phosphorus cycling in vegetation restoration and the assessment of soil quality.【Method】Soil samples were collected from fixed plots of bare land (BL), coniferous forest (CF), mixed coniferous broad-leaved forest (MF), and broad-leaved forest (BF) at the National Positioned Observatory for Red Soil Hills Ecosystems in Changting County, Fujian Province, China, and analysed the composition of soil agglomerates of all grain sizes by the dry sieve method, and the phosphorus content [total phosphorus (TP), effective phosphorus (AP), inorganic graded phosphorus, and the content of iron oxides (Fed), amorphous iron (Feo), and complex iron (Fep)] of aggregates of all grain sizes, respectively, were measured by the dry sieve method, and combined with the high-throughout sequencing for the determination of the characteristics of phosphorus-solbuiling bacterial (PSB) community structure and composition.【Result】(1)Soil aggregates were classified by particle size into <0.25 mm (micro-aggregates), [0.25, 2.00] mm (small aggregates), and >2.00 mm (large aggregates). The proportions from low to high were: micro-aggregates, large aggregates, and small aggregates. small aggregates were dominant, with a proportion ranging from 40% to 53%.(2) During the transition of forest types, the inorganic phosphorus content in soil aggregates primarily existed as occluded phosphorus (O-P), which accounted for over half of the total inorganic phosphorus. Calcium phosphorus (Ca-P) displayed an initial increase followed by a decrease. Moreover, the content of aluminum phosphorus (Al-P) and iron phosphorus (Fe-P) rose with the decrease in particle size of soil aggregates. (3) Within the same particle size of soil aggregates, free iron oxide (Fed) contents generally decreased, while complexed iron oxide (Fep) contents generally increased. The content of amorphous iron oxide (Feo) in >2.00 mm aggregates generally increased, and in [0.25,2.00] mm and <0.25 mm aggregates, it first increased, then decreased, and increased again. (4) A reduction in soil aggregate particle size was associated with an overall increase in the richness of PSB (Chao1, observed_species) and a general decrease in PSB diversity (Shannon, Simpson) with the transformation of forest types. 【Conclusion】As vegetation transitions from bare land to broad-leaved forests, the concentrations of amorphous iron oxides and complex iron forms increase, facilitating the formation and maintance of larger soil aggregates. However, PSB preferentially inhabit microaggregates and small aggregates, highlighting the critical role that these smaller aggregates play in supplying effective phosphorus within mature forest ecosystems.
【Objective】 Aegilops tauschii, has emerged as one of the most detrimental weed threatening winter wheat (Triticum aestivum) production systems across China. This study investigates the morphological and physiological adaptation mechanisms of A. tauschii under soil acidification stress, aiming to establish a scientific foundation for early warning systems and ecological management strategies against its invasive expansion.【Method】A controlled pot experiment was conducted using de Wit’s replacement series design to systematically compare seedling morphological characteristics, physiological-biochemical responses, and interspecific competitiveness between A. tauschii and wheat. Five soil pH gradients (7.5, 7.0, 6.5, 6.0, 5.5) and two planting patterns (monoculture and mixed planting) were established. 【Result】(1) Two-way ANOVA analysis revealed that different soil pH levels significantly affected seedling height, leaf area, and total biomass. (2) As soil pH decreased, seedling height, leaf area, and total biomass also decreased, indicating inhibited growth. However, when the pH decreased to 5.5, the reductions in seedling height, leaf area, and total biomass were significantly lower in A. tauschii than in wheat, suggesting a superior adaptation capacity of A. tauschii to low pH. (3) As pH decreased, superoxide dismutase (SOD) activity and proline content tended to increase. However, with a further decrease in pH (pH 6.0-5.5), relative electrical conductivity and thiobarbituric acid reactive substances (TBARS) content significantly increased, potentially due to exacerbated cell membrane damage at low pH. (4) Competitive indices (relative yield, relative yield total, and competition coefficient) indicated that A. tauschii consistently exhibited higher competitive abilities than wheat across all pH conditions. The competition coefficient (CB) of A. tauschii initially increased and then decreased with declining pH. 【Conclusion】A. tauschii demonstrates a capacity to adapt to decreasing soil pH through adjustments in morphological structure, biomass allocation patterns, and physiological characteristics. Within the experimental pH range (5.5-7.5), its stress resistance and competitive ability consistently exceeded that those of wheat.
【Objective】Cyclocarya paliurus is a multifunctional tree species. This study investigated the impacts of biochar types and their addition doses on soil chemical properties, leaf photosynthetic pigment content, and growth of C. paliurus seedlings, aiming to provide a scientific basis for biochar application in future C. paliurus plantations.【Method】A two-factor randomized block experimental design was employed to investigate the effects of three biochar types (C. paliurus biochar, straw biochar, and bamboo biochar) and three application rates (5%, 15% and 25% V/V, equivalent to 1.0%, 3.5%, and 6.5% m/m) on soil chemical properties, seedling growth, and leaf photosynthetic pigment content through a pot experiment.【Result】After 200 days of treatment, biochar application significantly increased soil pH, ammonium nitrogen, nitrate nitrogen, available phosphorus, and available potassium levels, while also enhancing chlorophyll a, chlorophyll b, and carotenoid contents in C. paliurus leaves. Application rate had a more pronounced effect on soil chemical indices than biochar type (P<0.05). Notably, adding 25% C. paliurus biochar increased soil pH by 32.1%, and 25% straw biochar significantly elevated available phosphorus and potassium levels by 145.3% and 250.0%, respectively, compared to the control. Biochar application also significantly influenced seedling growth and biomass production (P<0.05), with the 5% C. paliurus biochar treatment showing the most notable promotion in biomass production. Compared to the control, biomass in leaves, stems, roots, and total increased by 55.6%, 47.6%, 43.0%, and 47.0%, respectively, in the 5% C. paliurus biochar treatment. Correlation analysis revealed that seedling height and diameter growth were significantly positively correlated with leaf photosynthetic pigment contents. Additionally, all photosynthetic pigments were significantly and positively correlated with soil nitrate nitrogen (P<0.01), while only soil available potassium showed a significant correlation with carotenoid content (P<0.05).【Conclusion】Appropriate biochar application effectively enhances soil fertility and promotes C. paliurus seedling growth. Among treatments, the 5% C. paliurus biochar application proved optimal for maximizing biomass production.
【Objective】This research aims to investigate the spatiotemporal evolution characteristics of land use dynamics and ecosystem services in the central China river basins, and provide a scientific basis for ecological environment protection and territorial space planning in major grain-producing regions.【Method】Based on land use changes in the upper reaches of the Zhanghe River basin from 2000 to 2020, this study employed models such as InVEST and PLUS to explore the spatiotemporal evolution patterns of land use and ecosystem services under different scenarios in the past and future of the basin.【Result】(1) From 2000 to 2020, the basin experienced rapid cultivated land reduction and continuous construction land expansion. By 2035, under the natural development scenario, construction land expanded rapidly, encroaching on cultivated, grassland, and forest land. However, under cultivated land protection and ecological protection scenarios, construction land expansion was curbed, effectively preserving cultivated and forest land. (2) During 2000-2020, water yield and soil conservation increased, while carbon storage and habitat quality decreased. High-value areas for carbon storage, habitat quality, and soil conservation were found in the basin’s east-central and southeastern forests, whereas low-value areas were in the south-central construction land. Water yield exhibited an opposite spatial pattern, decreasing with increasing topographic gradient. (3) The ecological protection scenario yielded the greatest ecosystem service improvements and is suitable for future development.【Conclusion】The ecological protection scenario offers decision-making support for ecological protection and land development in the basin’s upper reaches. Future efforts should focus on resolving construction land-cultivated land conflicts and optimizing territorial space development strategies to promote land use structure transformation toward high ecosystem service provision.
【Objective】The study explored effects of changes in soil characteristics in zonal forests on soil respiration under nitrogen deposition in the central Yunnan Plateau. The study aimed to elucidate the mechanism underlying the response of soil respiration to nitrogen deposition in zonal forests, and provide a theoretical basis for the accurate assessment of the carbon budget and material cycle of subtropical forest ecosystems. 【Method】This study focused on two types of zonal forest soils, namely, evergreen broad-leaved forests and Quercus aquifolioides forests, in the central Yunnan Plateau. The soils were treated with different gradients of nitrogen, control [0 g/(m2·a) nitrogen, CK], low nitrogen [10 g/(m2·a) nitrogen, LN], medium nitrogen [20 g/(m2·a) nitrogen, MN], and high nitrogen [25 g/(m2·a) nitrogen, HN]. The variations in the characteristics of soil respiration (RS), temperature (T), humidity (W), organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), nitrate nitrogen ($\mathrm{NO}_{3}^{-}-\mathrm{N}$), ammonium nitrogen ($\mathrm{NH}_{4}^{+}-\mathrm{N}$) content, microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) were determined under nitrogen deposition. Additionally, the correlation between soil respiration and soil characteristics were determined to elucidate the mechanism underlying the effect of nitrogen deposition on soil respiration. 【Result】Compared to the CK group, soil respiration increased in the LN treatment group and decreased in the MN and HN treatment groups in the evergreen broad-leaf forests. Compared with the CK group, soil respiration increased with an increase in nitrogen application for all the treatment groups in the Q. aquifolioides forests. Soil respiration was lower in the dry season than that in the rainy season in both stands, and increased by 155.15% and 181.78% in the Q. aquifolioides and evergreen broad-leaf forests, respectively, in the rainy season compared to those in the dry season. The TOC, TN, $\mathrm{NO}_{3}^{-}-\mathrm{N}$, and $\mathrm{NH}_{4}^{+}-\mathrm{N}$ contents in the soil increased with the gradient of applied nitrogen in different seasons in both stands. Additionally, the contents of soil MBC in both stands were lower than that of the CK group in the rainy season at the different concentrations of nitrogen. The soil respiration of the evergreen broad-leaved forests exhibited a non-significant positive correlation with the pH, TP content and MBN (P > 0.05) in the dry and rainy seasons. Soil respiration in the Q. aquifolioides forests exhibited a non-significant positive correlation with the TOC, TN, $\mathrm{NO}_{3}^{-}-\mathrm{N}$, and $\mathrm{NH}_{4}^{+}-\mathrm{N}$ content, non-significant negative correlation with the TP content, MBC and MBN, and a significant negative correlation with the pH (P < 0.05) during the dry and rainy seasons. 【Conclusion】Nitrogen deposition can alter soil respiration by affecting the soil chemical indicators, including the TOC, TN, TP, $\mathrm{NO}_{3}^{-}-\mathrm{N}$, $\mathrm{NH}_{4}^{+}-\mathrm{N}$ content, MBC, and MBN. The findings revealed that moderate nitrogen deposition can promote soil respiration, while excessive nitrogen addition can inhibit soil respiration.
【Objective】The study aimed to investigate the differences in the degree of soil humification in the presence of foliar litter from different plant species in coniferous and broad-leaved forests in the special habitat of Wudalianchi volcanic kipuka, analyze the influence of soil humification in the home-field advantage during the decomposition of foliar litter, and provide a theoretical basis for exploring the process of soil formation and nutrient accumulation in different habitats in the volcanic forest of Wudalianchi. 【Method】Three decomposition plots were separately established in the coniferous and broad-leaved forests of Wudalianchi volcanic kipuka in late September 2016. The fresh leaves of three dominant trees, namely, Populus davidiana, Betula platyphylla and Larix gmelinii, were collected from the coniferous and broad-leaved forests. Then 10 g of the foliar litter was transferred to separate foliar litter decomposition bags. The litter decomposition interactive transfer experiment was established by transferring three foliar litter decomposition bags in separate litter plots at the same time. Then 0-10 cm of the soil directly underneath the foliar litter decomposition bags was retrieved from the decomposition plots from 2017 to 2019, around the 15th of May and October each year. The optical performance indices of the soil humus substances were detected, and the optical characteristics of the soil humus substances under different foliar litter were analyzed. The differences in the degree of soil humification following foliar litter decomposition in the home and away fields were also analyzed. 【Result】The decomposition of foliar litter in the away field altered the soil optical density (E4/E6), hue coefficient (ΔlogK), and relative chromaticity (RF) values of the humus substances during the 3-year decomposition period. The E4/E6 and ΔlogK values of the soil humification substances under the foliar litter of P. davidiana and B. platyphylla were higher in the home field than in the away field. However, the RF values of the soil humification substances were lower in the home field than in the away field, and the E4/E6, ΔlogK, and RF values under the foliar litter of L. gmelinii were lower in the home field than in the away field. The duration of decomposition and forest type had a significant effect on the E4/E6, ΔlogK, and RF values of the soil humification substances. Although the foliar litter species had no significant effect on the RF values, they significantly affected the values of E4/E6 and ΔlogK. The time-forest type, time-litter species, and time-forest type-litter species interactions were found to be significant.【Conclusion】Analysis of the decomposition of the foliar litter of broad-leaved and coniferous forests revealed that the degree of soil humification in the coniferous forest was higher than that in the broad-leaved forest. The decomposition of foliar litter in the coniferous forest exerted a “home-field advantage” on soil humification, which was not observed in the broad-leaved forest.
【Objective】The study aimed to determine the effects of a biocontrol agent used to treat zelkova (Zelkova schneideriana) wilt disease caused by Fusarium oxysporum on the microorganisms in the rhizospheric soil of zelkova. 【Method】The disease control efficiency and growth promoting effects of Bacillus velezensis HZM9 on zelkova trees challenged by F. oxysporum in a plantation in Jurong City, Jiangsu Province, were determined in this study. The diameter at breast height (DBH) and death rate of the zelkova trees were analyzed after one year of treatment. Samples of rhizospheric soil were collected from the region around the roots of zelkova trees, following which the activities of four enzymes (soil urease, alkaline phosphatase, catalase, and sucrase) and the structure of the microbial community in the soil were analyzed. 【Result】Compared to that of the untreated control, B. velezensis HZM9 treatment increased the DBH of zelkova trees by 17%, and reduced their death rate from 8.7% to 5.3%. Treatment with B. velezensis HZM9 had little influence on the activities of soil enzymes but increased the soil microbial diversity. In particular, the relative abundance of the beneficial microbial groups, including Mortierella sp., improved significantly. 【Conclusion】The findings indicated that B. velezensis HZM9 can significantly promote the growth of zelkova trees and alter the structure of the soil microbial community, which may benefit the long-term production of zelkova trees.
【Objective】Plantations play significant roles in mitigating climate change. Understanding the dynamics of soil organic carbon (SOC), particularly through its key components—particulate organic carbon (POC) and mineral-associated organic carbon (MAOC)—is crucial for predicting carbon sequestration in soil.【Method】This study investigated Metasequoia glyptostroboides plantations of varying ages (7, 16, 21, 26, 31, 36, 42 and 46 a) located in the Dongtai Forest Farm, Jiangsu Province. For each forest age, four replicated field plots were established, and soil samples were collected from five distinct depths: [0, 20), [20, 40), [40, 60), [60, 80), and [80, 100) cm. A range of soil physicochemical properties—including pH, ammonium nitrogen, nitrate nitrogen, total phosphorus, and available phosphorus—along with SOC fractions (POC and MAOC) were measured to examine the variation in POC and MAOC with the development of the plantations.【Result】POC in the [0, 20) cm soil layer was the dominant contributor to the soil organic carbon pool, and its accumulation was enhanced during the plantation’s development. Conversely, MAOC was the predominant fraction in the [20, 40) cm soil layer, but its response to stand age and development was less pronounced. As the forest age increased, the stability of SOC in the [0, 20) cm layer declined, making it more susceptible to decomposition and utilization. In contrast, SOC stability in the [20, 100) cm layers remained higher, supporting longer-term organic carbon storage. Correlation analysis revealed that POC was more responsive to environmental changes driven by stand development compared to MAOC.【Conclusion】As plantations mature, soil organic carbon accumulates primarily in the surface layer [(0, 20) cm] in the form of POC. The greatest accumulation occurs during the over-mature stage of the forest. Long-term plantation development significantly enhances the accumulation and retention of different fractions of surface soil organic carbon. Therefore, extending the primary cutting age of plantations would further optimize their role in mitigating global climate change.
【Objective】This study aimed to reveal the effects of drought on soil microbial biomass carbon (C), nitrogen (N), and phosphorus (P), as well as their ecological stoichiometric characteristics in poplar plantations. We also aimed to understand the soil C, N, and P biogeochemical cycles in poplar plantations under a future global drought scenario and provide a theoretical basis for the rational management of these plantations.【Method】Soil microbial biomass C (MBC), N (MBN) and P (MBP), along with their ecological stoichiometric characteristics (i.e., MBC/MBN, MBC/MBP, and MBN/MBP), and soil physicochemical properties, were examined in a poplar plantation (Populus deltoides) at Dongtai Forest Farm, Jiangsu Province, China. Three treatments were established in this study, control (CK), 30% throughfall reduction (D1), and 50% throughfall reduction (D2).【Result】(1) Soil MBC, MBN, and MBP were significantly reduced under drought conditions compared to the control, with reductions of 16.09%, 22.60%, and 32.49%, respectively, for the D2 treatment. Both MBC/MBN and MBC/MBP were significantly increased under drought conditions, with increases of 10.33% and 25.15%, respectively, in the D2 treatment, while soil MBN/MBP ratios did not change significantly. (2) Soil MBC, MBN and MBP showed significant seasonal variations, ranging from 344.67 to 500.12 mg/kg, 45.21 to 63.22 mg/kg, and 15.33 to 23.48 mg/kg, respectively. MBC, MBN, and MBP contents were lower in summer and fall than in winter and spring. In contrast, seasonal variations in MBC/MBN and MBC/MBP showed opposite trends to those of MBC, MBN, and MBP, while seasonal variations in MBN/MBP were not significant. (3) Compared with the control, drought treatments significantly reduced $\mathrm{NH}_{4}^{+}-\mathrm{N}$, dissolved organic carbon (DOC), available phosphorus (AP), and soil water content (SWC) by 68.81%, 32.77%, 29.87%, and 11.05%, respectively. Drought treatments increased soil pH and $\mathrm{NO}_{3}^{-}-\mathrm{N}$ content by 1.51% and 194.34%, respectively. Correlation analyses showed that soil MBC, MBN, and MBP had highly significant positive correlations with SWC and total nitrogen (TN) and significant or highly significant negative correlations with SOC, $\mathrm{NO}_{3}^{-}-\mathrm{N}$ content, and the total carbon to nitrogen ratio (C/N). Soil MBC/MBN, MBC/MBP, and MBN/MBP showed significantly or highly significant positive correlations with $\mathrm{NO}_{3}^{-}-\mathrm{N}$ and C/N and significant or highly significant negative correlations with SWC and TN content.【Conclusion】Drought significantly affected soil microbial C, N, and P and their ecological stoichiometric characteristics in poplar plantations, potentially altering the soil nutrient balance and cycling in these plantations.
【Objective】 This study investigated the effects of soil amendments on the color changes in Acer×freemanii leaves and explored the relationship between leaf color changes and leaf mineral element content. The findings aim to provide a theoretical basis for addressing the issue of non-red coloration in Acer×freemanii leaves.【Method】Six-year-old Acer×freemanii trees were used as the experimental material. Five gradient treatments combining sulfur powder and desulfurization gypsum as soil alkaline amendments were applied. Leaf color changes were observed during four autumn time periods, with measurements of leaf pigments and the contents of ten mineral elements.【Result】Soil alkaline amendment treatments significantly influenced the contents of chlorophyll, carotenoids, and anthocyanins in leaves, as well as leaf color parameters (L*, a* and b* values). Among the treatments, T5 (1.94 kg/m3 sulfur powder and 2.33 kg/m3 desulfurized gypsum) resulted in the most vibrant leaf coloration and an extended period of color development. The treatments also significantly affected the content and variation trends of mineral elements in leaves. Correlation analysis revealed that nitrogen (N) showed a strong positive correlation with chlorophyll and carotenoids (P<0.01) and a strong negative correlation with anthocyanins (P < 0.01). Potassium (K) showed a significant negative correlation with carotenoids (P<0.05). Calcium (Ca) and Magnesium (Mg) showed a strong negative correlation with chlorophyll (P<0.01) and a significant positive correlation with anthocyanins (P<0.05). Manganese (Mn) showed a strong positive correlation with carotenoids (P<0.01).【Conclusion】Lowering soil pH within a certain range enhances the coloration of Acer×freemanii leaves. Soil amendments have a significant impact on pigment and mineral element contents in the leaves. Mineral elements, particularly N, K, Ca, Mg, and Mn, show strong correlations with leaf color changes, emphasizing their importance in managing leaf coloration.
【Objective】This study evaluated soil quality under different types of plantation vegetation restoration in Karst areas, aiming to provide guidance on selecting suitable tree species and improving soil quality. 【Method】Three types of plantation forests—Cupressus duclouxiana forest, Robinia pseudoacacia forest, and C. duclouxiana-R. pseudoacacia mixed forest—along with unplanted land (control) in Guizhou Province, were selected for the study. The soil physical, chemical, and enzymatic characteristics were analyzed. Redundancy analysis and principal component analysis (PCA) were used to assess soil fertility quality, while total data set (TDS), minimum data set (MDS), and gray correlation degree method (GRA) were employed to evaluate soil fertility. 【Result】(1) Compared with unplanted land, soil water content, porosity, organic matter, total nitrogen, alkali-hydrolyzed nitrogen, total phosphorus, and available phosphorus content were significantly higher in plantation forests. Conversely, soil bulk density, pH, total potassium, and available potassium were significantly lower. (2) Except for alkaline phosphatase, the activities of urease, polyphenol oxidase, sucrase, and catalase were the highest in the C. duclouxiana-R. pseudoacacia mixed forest. Urease, alkaline phosphatase, and catalase activities were higher in plantations than those in unplanted land. (3) The minimum data set derived from PCA was suitable for soil quality evaluation in Karst plantations. This data set included soil total nitrogen, total potassium, available potassium content, non-capillary porosity, alkaline phosphatase, and polyphenol oxidase activities. (4) Soil quality evaluations based on MDS align with those based on TDS and grey correlation degree. The soil quality order was as follows: C. duclouxiana-R. pseudoacacia mixed forest > R. pseudoacacia forest > C. duclouxiana forest > unplanted land. The mixed forest demonstrated significantly better soil quality than the pure forests. 【Conclusion】 During vegetation restoration and plantation development in Karst areas, following the principles of tree adaptation and site suitability, and focusing on constructing mixed forests, can enhance overall soil quality and improve the ecological benefits of artificial vegetation restoration.
【Objective】The purpose of this study was to explore how soil infiltration responds to different elevation gradients in Liziping National Nature Reserve, Sichuan. 【Method】Soil samples were collected from four elevation gradients (1 900, 2 100, 2 300, and 2 500 m) within the nature reserve. Soil infiltration characteristics at these gradients were measured using the ring knife method. Key factors affecting soil infiltration were identified through path and correlation analyses. Additionally, the suitability of infiltration models, including Kostiakov, Philip and Horton, was evaluated by fitting and analyzing the data. 【Result】Soil infiltration rates showed a highly significantly negative correlation with elevation (P < 0.01). Soil microbial biomass had a significant positive correlation with infiltration rates (P < 0.05), promoting water infiltration. In the first 20 min, soil infiltration rates decreased by about 50% at elevations of 1 900 and 2 100 m, and by 72% to 85% at elevations of 2 300 and 2 500 m. The rate of infiltration decreased at 2 300 and 2 500 m was significantly faster that than at 1 900 and 2 100 m, primarily due to differences in soil organic matter, aggregate grain structure, and microbial biomass. The model fitting showed that the R2 values were 0.896-0.959 for the Kostiakov model, 0.874-0.965 for the Philip model, and 0.945-0.965 for the Horton model. Based on the R2 values and the alignment between fitted and measured values, the Kostiakov model was found to be the most suitable for the study area. 【Conclusion】Elevation gradients significantly affect soil infiltration characteristics, primarily influenced by soil organic matter, aggregate grain structure, and microbial biomass.
【Objective】Roof greening has become a popular method for increasing urban green spaces and mitigating the urban “heat island effect”. Recently, biochar, known for its lightweight and highly porous nature, has been utilized as a soil amendment in the agricultural and forestry sectors. This study explores the impacts of varying biochar application rates and pyrolysis temperatures on soil runoff and nutrient content in roof greening, to assess biochar’s potential for enhancing urban roof greening practices.【Method】The experiment involved three levels of biochar application (0%, 10% and 20%, volume fraction) and three pyrolysis temperatures (300, 400 and 500 ℃), with four replicates per treatment. Each planting box was filled with a 10 cm thick layer of treated soil matrix and planted with Sedum lineare. Soil runoff was collected and analyzed after each rainfall event.【Result】The findings indicated that biochar application could increase soil pH and significantly reduce the levels of total nitrogen (TN) and dissolved organic carbon (DOC) in the runoff. While a 10% biochar addition decreased the total phosphorus (TP) concentration in the runoff, a 20% addition had the opposite effect. Moreover, biochar was effective in reducing soil runoff and nutrient concentration, thus minimizing nutrient loss from the soil. There was no significant difference in the effects of biochar processed at different pyrolysis temperatures on runoff quality. 【Conclusion】Optimal biochar application can significantly decrease N and P loss in roof soil runoff, indirectly reducing urban runoff pollution. This suggests a promising application for biochar in managing urban stormwater runoff.
【Objective】 The study aimed to investigate the response of the fine roots of the 2-year-old ‘Beilin 1’ cultivar of young Populus tomentosa to variations in the species composition of trees and stand density, and to study their distribution and adaptation strategies following variations in species composition and stand density at the young stand stage. The initial plantation and the mixed configuration were used as references.【Method】A mixed P. tomentosa forest (plant spacing 3 m × 6 m) and pure biennial P. tomentosa forests of three different densities (3 m × 3 m, 3 m × 6 m, and 6 m × 6 m) were selected as the research objects. The root drilling method was used for sampling, and the samples were collected from a depth of 150 cm in the vertical direction, with every 10 cm representing a different layer. The sampling points were located at distances of 10, 30, 50, 100, 150, 200, 250 and 300 cm from the trees in the horizontal direction, while the sampling points for the 3 m × 3 m stand were located at distances of 10, 30, 50, 100 and 150 cm, a total of 1 305 root samples were obtained. The obtained root samples were scanned, dried, and weighed for measuring the dry mass. The morphological characteristics of the fine roots and the biomass data at various depths and horizontal distances were assessed across different species compositions and stand densities. 【Result】The findings revealed that the species composition did not significantly affect the fine root biomass density, but significantly affected the root length density and root surface area density. The characteristics of the fine roots of P. tomentosa in the pure and mixed forests did not exhibit any alterations in the vertical direction, all decreased with an increase in soil depth. The fine root biomass density of P. tomentosa in the mixed and pure forests was primarily concentrated at distances of 0-50 and 0-10 cm, respectively, from the trees in the horizontal direction. The biomass density of fine roots of P. tomentosa in mixed forests was mainly concentrated at 0-50 cm. Analysis of the two-dimensional distribution revealed that the fine roots of P. tomentosa were more densely distributed at greater depths in the mixed forest, their horizontal distribution was relatively uniform, and the horizontal lateral roots were more elongated. The stand density did not significantly affect the fine root biomass density, and the root length density, root surface area density, and average diameter of the roots in the high-density stands were significantly greater than those of the other two stands with different densities. The fine root biomass density in the 40-50 cm soil layer of the 3 m × 3 m stand was significantly higher than that of the other two stands (P < 0.05). The finer roots were more densely distributed in the deeper soil layers. The fine root biomass density in the 3 m × 6 m and 6 m × 6 m stands decreased gradually at increasing soil depths, while that of the 3 m × 3 m stand gradually increased in the 0-60 cm soil layer, indicating a unimodal distribution pattern. The root length density and root surface area density of the 3 m × 3 m stand at 150 cm from the trees in the horizontal direction were significantly higher than those of the other two stands of different densities. Analysis of the two-dimensional distribution pattern revealed that the fine roots in the 3 m × 3 m stand were more densely distributed at greater depths, while those in the 3 m × 6 m stand were more horizontally elongated.【Conclusion】Mixing significantly reduced the root density and root surface area density of P. tomentosa. An increase in stand density caused the fine roots to be gradually elongated with depth, and increased their distribution in the deeper soil layers. The fine root biomass density gradually decreased in the horizontal direction at increasing distances from the trees in the high-density stand. The species composition and stand density did not significantly alter the fine root biomass density of young 2-year-old P. tomentosa trees, but the root length density and root surface area density in the pure forest and the 3 m × 3 m stand were significantly higher than those of the mixed forest and the other two stands with different densities. The growth of the fine roots of P. tomentosa was most vigorous in the pure forest and in the 3 m × 3 m high-density stand. The soil water and nutrients were fully utilized by morphological plasticity rather than by alterations in biomass, and the soil resources were more effectively utilized in the young forest than in the mixed forest and in the forest stands of varying densities.
【Objective】 Plant growth-promoting rhizobacteria play an important role in promoting plant growth and development, improving the soil microenvironment, and aiding the development of sustainable forestry practices. The functional bacteria in the rhizospheric soil of Phyllostachys edulis, and their effects on seedling growth were investigated to provide a scientific basis for the development and utilization of new microbial resources from bamboo, improving the productivity of bamboo forests, and enhancing the functions of ecosystem services.【Method】The rhizosphere soil of P. edulis was selected as the research object, and the rhizosphere bacteria were isolated using traditional dilution culture methods. A phylogenetic tree based on the 16S rRNA gene sequences was constructed using the maximum-likelihood method. In vitro functional evaluation was performed based on the functional plates and specific color changes. The effects of the functional strains on the germination of P. edulis seeds and the growth of seedlings were finally investigated with re-inoculation experiments.【Result】 A total of 39 rhizosphere bacterial strains from 23 genera belonging to 12 families under three phyla, were isolated and cultured. Actinomycetota and Bacillaceae were the dominant phylum and family with relative abundances of 41.0% and 25.6%, respectively. Functional analysis of the 39 bacterial strains revealed that 20 and three strains were capable of producing IAA (indole-3-acetic acid) and siderophores, while five and three strains were capable of dissolving potassium and inorganic phosphorus, respectively, and seven strains were capable of mineralizing organic phosphorus. The strain SD2N7 was capable of simultaneously producing IAA, dissolving inorganic phosphorus and potassium, and mineralizing organic phosphorus. Based on the physiological and biochemical characteristics and the 16S rRNA gene alignment, strain SD2N7 was identified as Rahnella woolbedensis. The re-inoculation experiments revealed that strain SD2N7 could significantly shorten the germination period of P. edulis seeds and promote the elongation of the roots and leaves of P. edulis seedlings.【Conclusion】 There were abundant functional microbial resources in the rhizosphere soil of P. edulis, which were capable of producing IAA or siderophores, dissolving phosphorus and potassium, and performing other functions. The back-grafting test additionally demonstrated that strain SD2N7 significantly promoted seed germination and the growth of P. edulis seedlings.
【Objective】Soil faunas are crucial components of forest ecosystem. This study investigated the distribution characteristics and seasonal variation of soil macrofauna in Metasequoia glyptostroboides plantations of different ages. We analyzed differences in the community structure, seasonal dynamics, and influencing mechanisms of surface soil macrofauna, providing a theoretical basis for future studies on soil fauna community structure in these plantations.【Method】We assessed soil macrofauna community dynamics across nine M. glyptostroboides plantations (seven, 11, 16, 21, 26, 31, 36, 41, and 46 years old) using a randomized block design with four replicate plots per age group, located in a coastal area of northern Jiangsu Province, China. Collections were made in summer (August) and autumn (October) using pitfall traps, and samples were sorted and identified under a stereomicroscope in the laboratory. Additionally, soil samples from the 0-15 cm layer were collected for physicochemical analysis.【Result】We collected a total of 14 289 surface soil macrofauna individuals from 16 orders and 23 families. The dominant groups were Armadillidae and Oniscidae. Significant differences were observed in the dominant and common groups of soil macrofauna among plantations of different ages. The 11-year-old plantation had the highest number of soil macrofauna, while the 36-year-old plantation had the lowest. In terms of seasonal variation, the total number of surface soil macrofauna was higher in August than in November, whereas species richness was greater in November than in August.【Conclusion】The study highlights that both stand development and seasonal variation significantly influence the community structure of surface soil macrofauna in M. glyptostroboides plantations. As the forest matures, the total number, species diversity and diversity index of surface soil macrofauna increase, reaching a high level in middle-aged forests.
【Objective】This study explored the patterns and environmental factors that drived β diversity and its components in plant communities on the northern slope of Changbai Mountain, to provide a theoretical basis for biodiversity conservation and ecosystem management in the area.【Method】The betapart package of R was used to decompose the components (turnover and nestedness) of β diversity. The generalized dissimilarity modelling (GDM) was used to explore the environmental factors that drived β diversity and its components.【Result】Decomposition of the β diversity components revealed that the β diversity of the plant communities was dominated by the turnover, indicating that species replacement leads to differences in species composition among communities. The results of GDM analysis showed that 13 environmental variables explained 32.63%-66.52% of the β diversity and the turnover components of the plant communities. The mean annual air temperature significantly influenced the arbor β diversity. The arbor β diversity was significantly affected by the annual precipitation and soil bulk density when they reached values higher than 710.00 mm and 1.07 g/cm3, respectively. The turnover components of arbor β diversity were primarily affected by the mean annual air temperature, soil bulk density, and slope. The turnover rate increased with an increase in the values of the predictive variables once the threshold was surpassed. The growth rate of shrub β diversity and its turnover components exhibited a downward, constant and upward trend, respectively, for shrub plants following an increase in air temperature seasonality, slope and mean annual air temperature. However, in response to the major determinants, the gradient changes in the β diversity of herbs and its turnover components increased with altitude, decreased with rising isothermality, and initially increased and then decreased following an increase in soil organic carbon.【Conclusion】Altogether, the findings revealed a turnover pattern in the species composition of plant communities in the northern slope of Changbai Mountain, indicating that biodiversity conservation efforts should focus on multiple species and at multiple regions. The β diversity patterns are primarily affected by environmental factors. The arbor β diversity and its turnover components are primarily affected by the mean annual air temperature, while those of shrub plants are mainly affected by seasonal variations in air temperature, and those of herbs are primarily limited by the altitude.
【Objective】This study investigates the growth response and nutrient utilization of the Camellia oleifera root system across different root orders under drought and nitrogen application. It aims to analyze how water and nitrogen affect root growth, nitrogen uptake, distribution and utilization, and to provide theoretical support for understanding the relationship between plant root architecture and nutrient strategies under climate warming. 【Method】 Two-year-old C. oleifera ‘Changlin 53’ trees were used. A pot experiment with 15N isotope tracing technology was conducted, setting two drought levels: normal irrigation (soil moisture content 75% ± 5%) and drought (soil moisture content 30%±5%). Two nitrogen application levels were used: no nitrogen and 15N-labeled ammonium nitrate (2.88 g/plant). After 75 days of drought treatment, the biomass, total nitrogen content, percentage of nitrogen from fertilizer (Ndff), and nitrogen use efficiency of roots of different diameter classes of C. oleifolia seedlings were measured. 【Result】 Under drought stress, there was a negative correlation between biomass and nitrogen content in grade 1-3, grade 5, and grade 6 roots, while a positive correlation was observed in grade 4 roots. Drought significantly affected 15N content and Ndff in all root diameter classes (P < 0.05). Drought inhibited 15N accumulation in all root diameter classes, with Ndff in grades 1-3 being most affected. Drought increased nitrogen distribution in roots, especially in grade 5 roots, which saw a 93.10% increase. However, the nitrogen use efficiency was inhibited to varying degrees across different root diameter classes. 【Conclusion】Nitrogen application increased root biomass and nitrogen allocation to coarse roots under drought but reduced fine root biomass and nitrogen accumulation. Drought significantly impacted the absorption, utilization, and distribution of fertilizer nitrogen in roots of all levels, enhancing nitrogen distribution, particularly in roots above grade 5, but inhibiting 15N absorption and utilization in roots of grades 1-4.
【Objective】In arid and semiarid regions, efficient water use for vegetation construction and restoration to maximize functional diversity has become a key research focus due to scarce precipitation. The study of plant water-carbon coupling processes is crucial in this context.【Method】This research focused on Platycladus orientalis, the main afforestation species in Beijing mountainous areas. An indoor pot simulation experiment was conducted over six months to measure the individual transpiration water consumption, carbon sequestration, and respiration rate of P. orientalis under different CO2 concentrations and soil moisture levels. Water use efficiency was used as the water-carbon coupling index to analyze these processes and their influencing factors. 【Result】(1)The transpiration rate of P. orientalis was significantly affected by soil water content, peaking at 70%-80% field water capacity and then slightly decreased. (2) Both soil water content and CO2 concentration significantly influenced individual carbon processes and water-carbon coupling. (3) Instantaneous and short-term water use efficiency reached maximum at CO2 concentrations of 600 and 800 μmol/mol with 50%-60% field water capacity. (4) There was a significant linear correlation between cumulative carbon sequestration and water consumption (P < 0.05), with a maximum ratio of 24.35 mmol/mol at a CO2 concentration of 800 μmol/mol and 50%-60% field water capacity. 【Conclusion】The increase of carbon dioxide concentration was conducive to alleviating the individual scale drought stress, and soil water content significantly affected the water-carbon process of P. orientalis.
【Objective】 The foliar nitrogen content is an important functional trait of plants. Herein, the effect of drought on the nitrogen content of Moso bamboo (Phyllostachys edulis) leaves was quantitatively analyzed. The study provides a theoretical basis for the sustainable and efficient management of bamboo forests under the current global climate change scenario.【Method】A wild bamboo forest located in Miaoshanwu Forest Farm of Qianjiangyuan Forest Ecosystem Research Station was selected as the research object in this study. The 2-year experimental data pertaining to precipitation exclusion in the bamboo forest, and the spatiotemporal distribution characteristics of the nitrogen content per unit mass of Phyllostachys edulis leaves under different drought periods and their response to drought stress were analyzed. 【Result】 The annual average nitrogen content per unit mass of bamboo leaves following 1 and 2 years of precipitation exclusion was high than that under natural growth conditions (CK). Although the annual average nitrogen content after 2 years of precipitation exclusion was higher than that after 1 year of exposure to drought, the difference was not significant. Exposure to drought for 1 year increased the foliar nitrogen content during summer and winter, compared to that of the CK; however, the foliar nitrogen content remained stable in summer, autumn, and winter following prolonged exposure to drought. With the exception of the nitrogen content of the leaves in the upper canopy in winter, the foliar nitrogen content following 1 year of precipitation exclusion was significantly higher than that of the CK in summer and winter (P < 0.05). The nitrogen content of the upper leaves was significantly higher than that of the CK in winter after 2 years of precipitation exclusion. The nitrogen content of the upper and lower leaves differed significantly in summer (P < 0.05) after 1 year of precipitation exclusion. The prolongation of drought exposure caused significant differences between the foliar nitrogen content of drought-exposed and CK plants, depending on the season and age of the bamboo. However, the foliar nitrogen content of different degrees of bamboo did not differ significantly from that of the CK during spring. The foliar nitrogen content of first degree (1-2 years old) bamboo plants under drought stress was significantly higher than that of the CK in winter. There were no significant differences between the foliar nitrogen content of different degrees of bamboo plants in spring and summer, following 1 or 2 years of precipitation exclusion. However, the foliar nitrogen content of the first (1-2 years old) and fourth (7-8 years old) degree bamboo plants differed significantly in autumn and winter (P < 0.05). The annual average foliar nitrogen content of the elderly bamboo plants exposed to prolonged drought was relatively high compared to that of the plants exposed to drought for 1 year. 【Conclusion】Analysis of the 2-year data obtained during precipitation exclusion demonstrated that the average foliar nitrogen content of bamboo following precipitation exclusion was higher than that of the CK, but the differences were not significant. The effects of the duration of drought exposure on the foliar nitrogen content were influenced by the season and plant age. The prolongation of precipitation exclusion increased the number of seasons during which the foliar nitrogen content of the drought-exposed plants was higher than that of the CK. Additionally, the number of canopy layers of drought-exposed and control plants that exhibited significant differences in foliar nitrogen content was reduced following the extension of precipitation exclusion, and the differences were limited to individual canopies. The season and age of the bamboo plants need to be considered for the nutrient management of Moso bamboo in future, under the current climate change situation.
【Objective】This study aims to investigate the characteristics of leaf functional traits in Tirpitzia sinensis across different Karst fissure networks, and provide a theoretical basis for understanding plant growth adaptability mechanisms in Karst areas.【Method】In this study, we selected typical dominant shrub habitats of T. sinensis with various rock fissure characteristics: high dip angle, short track length, fewer turns, multiple connections, high density, and aggregation type (type Ⅰ); moderate dip angle, moderate track length, multiple turns, moderate connections, moderate density, and uniform type (type Ⅱ); and low dip angle, long track length, moderate turns, fewer connections, low density, and random type (type Ⅲ). We investigated the response of leaf functional traits to different rock fissure networks and soil physicochemical properties using One-way analysis of variance and correlation analysis. 【Result】The nutrient and water contents of fissure soil were the highest in type Ⅰ rocky habitats, followed by type Ⅱ, and the lowest in type Ⅲ, while soil pH showed an opposite trend. Soil nutrients in type Ⅲ were significantly lower than in type Ⅰ (P < 0.05), but there were no significant differences in soil pH or water content. Significant differences were found in leaf chemical traits among different rocky habitats (P < 0.05), but not in structural traits. Leaf nutrient concentration and specific leaf area were highest in type Ⅰ, followed by type Ⅱ and the lowest in type Ⅲ, with leaf dry matter content showing the opposite trend. Leaf N/P mass ratios and leaf thickness were the highest in type Ⅱ, followed by type Ⅲ, and the lowest in type Ⅰ. The dip angle and connectivity of rock fissures were the main factors affecting soil physicochemical properties. Soil organic carbon, total nitrogen, available nitrogen, and available phosphorus content were the primary factors influencing leaf chemical traits and leaf area, which were significantly affected by the connectivity of the rock fissure network. The leaf nitrogen/phosphorus mass ratio was higher than 16 across the three rocky habitats, which indicated that T. sinensis growth was phosphorus-limited. Compared with other Karst shrubs in the same area, the growth rates of T. sinensis in the three rocky habitats were slower, reflecting a more conservative nutritional investment strategy. 【Conclusion】The rock fissure network indirectly affects leaf functional traits primarily by altering soil physicochemical properties, with leaf chemical traits showing greater plasticity than structural traits. In type Ⅲ rocky habitats, T. sinensis is most susceptible to nutrient stress, demonstrating pronounced tolerance to nutrient-poor conditions in its leaf functional traits.
【Objective】This study aims to explore the degradation degree and area differences of soil structure in different areas across the typical black soil region, and to provide reference and basis for the protection of black soil and the restoration of degraded cultivated land. 【Method】 The characteristics of soil aggregates, soil porosity and water retention capacity, and soil three-phase structure of uncultivated grassland and farmland (cultivated for 60 years) were measured by dry-wet sieving and cutting ring method, and were comparatively analyzed in three areas (hill area, rolling hill area, low mountain area). 【Result】The results showed that the mechanical and water stability of aggregates, porosity, and water retention quality of soil were significantly better in the uncultivated hill area and rolling hill area than those in the low mountain area, while the generalized soil structure index was significantly lower in the low mountain area. The degradation of the mechanical stability of aggregates was not obvious after long-term cultivation (60 years), while the degradation of water stability of aggregates was in the order of low mountain area > hill area > rolling hill area. The total porosity and water retention capacity of the soil in the hill area and rolling hill area degraded seriously, while it showed an increased tendency in the low mountain area. The ratio of solid, liquid and gas phases of soil approached the ideal three-phase structure and was beneficial to crop growth in the 0-10 cm soil depth of the hill area and rolling hill area, but there was no significant change in the low mountain area. The increase in the solid phase proportion leads to the obvious degradation of the soil three-phase structure in the 20-40 cm soil depth of all three areas. 【Conclusion】The soil structure in uncultivated areas has regional differences in the typical black soil region. The hill area and rolling hill area had a superior aggregate structure, soil pore structure, and water retention capability, while the low mountain area had a superior soil three-phase structure. Farmlands in the three different areas across the typical black soil region showed a trend of degradation, with varying degrees of degradation among the areas. The soil pore structure and the three-phase structure of the hill area and rolling hill area degraded more seriously, while the aggregate structure of the low mountain area degraded more seriously.
【Objective】 In order to clarify the coupling coordination relationship between the ecosystem services provision level and well-being level of residents, along with its key influencing factors in ecological resource-rich, former concentrate contiguous special hardship areas, a scientific basis is provided for these areas to formulate development plans and policies aimed at realizing common prosperity based on ecological resources. 【Method】 An evaluation index system for residents’ well-being level was constructed by focusing on the former concentrated contiguous special hardship areas in the Luoxiao Mountain area as the research subject. The ecosystem services provision level was determined using the InVEST model, and the coupling coordination relationship between the ecosystem services provision level and residents’ well-being level, as well as its influencing factors during the period from 2000 to 2020 in the Luoxiao Mountain area, was analyzed utilizing the coupling coordination degree model and econometric regression model. 【Result】 (1) The water conservation, soil conservation, and carbon sequestration services in the Luoxiao Mountain area were slowly decreasing and exhibit varying spatial distributions. (2) The residents’ well-being level increased by 181%. (3) The supply levels of water conservation, soil conservation, and carbon sequestration services, along with the population’s well-being, show a coupling coordination relationship, although with a downward trend. (4) Per capita cultivated land area, the number of industrial enterprises above a large scale, and the number of beds in social welfare centers positively influenceed changes in the coupling coordination relationship between the ecosystem services provision level and the well-being level of residents in the Luoxiao Mountain area. 【Conclusion】A robust mechanism for the industrial transformation of ecosystem services and product values should be established. Ecological industrial enterprises above scale must be vigorously developed, capitalizing on ecological resource advantages. Local residents should be actively employed, contributing to the sustained growth of their incomes to enhance the coordinated relationship between the two systems.
【Objective】The effects of biogas slurry on soil carbon (C), nitrogen (N), and phosphorus (P) contents were studied in poplar plantations in coastal areas of northern Jiangsu, China. This research aims to provide a theoretical basis for the scientific utilization of biogas slurry, the optimization of fertilization technology, and the promotion of sustainable development in poplar plantations.【Method】The experiment employed a randomized block design with four levels of biogas slurry application: CK (0 m3/hm2), L (125 m3/hm2), M (250 m3/hm2) and H (375 m3/hm2). Soil samples were collected from different depths: 0-20 cm (surface layer), ≥20-40 cm (middle layer), and ≥40-60 cm(deep layer) using a continuous soil coring method. The study examined the effects of various biogas slurry concentrations on soil C, N and P contents across different soil layers and growing seasons in the poplar plantations.【Result】Biogas slurry application significantly increased the soil organic carbon (SOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), total phosphorus (TP), and available phosphorus (AP) in the topsoil (0-20 cm). It also significantly decreased the C/N ratio (mass fraction ratio, the same below) and MBC/MBN ratio in the topsoil. Additionally, biogas slurry significantly increased DOC and TP in the ≥20-40 cm soil layer. However, in the deep soil (≥40-60 cm), biogas slurry had no significant effect on soil C, N, and P levels. Biogas slurry application also significantly reduced soil pH across all layers.【Conclusion】Our research indicates that biogas slurry, as a high-quality, quick-acting organic fertilizer, significantly increases nutrients such as C, N, and P in surface soil but does not affect deep soil. It also reduces soil pH and C/N ratio in coastal saline-alkali soil, improving soil fertility. However, further research is needed to determine whether excessive application could risk phosphorus and nitrogen leaching and potential ecological pollution.
【Objective】The frequent extreme weather events that are likely to be associated with global climate change may have an impact on plant water use. The aim of this study was to explore how mixed forest species adapt by accessing different water sources in the southern hilly region of China under different precipitation conditions.【Method】The stable hydrogen and oxygen isotopes in the xylem, soil, and groundwater from mixed Quercus acutissima and Pinus massoniana forests in the southern hilly region were measured and multi-source linear mixed models (Iso-Source) used to compare and analyze the water use in the forest under different precipitation gradients.【Result】Q. acutissima was found to mainly use soil water from the shallow layer ([10,30) cm) under low precipitation conditions, with a utilization rate of 62.0%; however, under heavier rain the species turns to deep soil water ([80,100) cm) and groundwater, with utilization rates of 34.2% and 44.6%, respectively. P. massoniana mainly uses groundwater and deep soil water ([80,100) cm) with utilization rates of 21.2% and 21.1%, respectively, under low precipitation conditions; however, the species changes to use soil water from depths of (0,10) cm and [10,30) cm layers, with utilization rates of 27.2% and 53.3%, respectively, when precipitation increases.【Conclusion】Q. acutissima and P. massoniana adapt differently to precipitation changes in terms of the water source used, and the depth from which water is sourced changes under different precipitation gradients. The different water use patterns of these species will reduce water competition under the expected frequent extreme precipitation events expected in the future. The results of the study provide a theoretical basis for the implementation of improved forest management.
【Objective】The BpGLK transcription factor of Betula platyphylla is involved in regulating chloroplast development and leaf color. The leaf color of B. platyphylla with inhibited BpGLK expression is yellow-green during the growth period, which holds great ornamental value in landscaping. However, as a genetically modified crop, concerns exist regarding the potential adverse environmental effects of widespread use. This study aims to examine the impact of transgenic BpGLK B. platyphylla on soil enzyme activity and the composition of rhizosphere soil bacterial and fungal communities, providing theoretical data for future environmental release and commercialization.【Method】Three-year-old transgenic B. platyphylla (OE and RE strains) and wild-type (WT) B. platyphylla are used as materials. Soil sucrase, urease, neutral protease, catalase, and cellulase activities were measured using the spectrophotometric method. In addition, 16S rRNA and ITS sequencing analyses of rhizosphere soil microorganisms were conducted using the Illumina-Miseq high-throughput sequencing platform. The richness and diversity of bacterial and fungal communities, structural differences, and community composition in rhizosphere soil were analyzed to understand the effects of transgenic activity on soil enzyme activity and microbial composition in the rhizosphere soil of B. platyphylla.【Result】Significant differences (P < 0.05) are observed in soil urease, sucrase, cellulase and neutral protease activities between BpGLK-transformed B. platyphylla and WT strains at four time points (June 15, July 15, August 15 and September 15). However, catalase activity showed significant differences between WT and some transgenic strains. Soil urease and cellulase activities decrease significantly in mid-August and mid-September. The activity of soil neutral protease in OE strains was higher than that of the WT strain at all four periods (P < 0.05). At the rhizosphere bacterial community level, Burkholderia, a growth-promoting function, was the dominant genus in transgenic and WT strains. The relative abundance of Burkholderia in the rhizosphere soil of transgenic strains significantly increased. At the rhizosphere fungal community level, Tomentella dominated the rhizosphere of transgenic RE strains, while Clavulina dominated the rhizosphere of WT and OE strains. The relative abundance of Laccaria was significantly lower in OE and RE strains (P < 0.05). The Observed, Chao1, Shannon and Simpson indices of transgenic B. platyphylla did not differ significantly from those of WT strains, while the community abundance and diversity of RE strains were significantly higher than those of WT strains. The difference between OE and WT strains was not significant. Venn diagram analysis revealed significant differences in ASV composition between transgenic and WT strains. In contrast, principal component analysis showed slight differences in community composition between RE and WT strains, while the difference between OE and WT strains was relatively larger. However, the difference between OE and WT strains remainsed smaller than that between RE and WT strains.【Conclusion】The results indicated that the introduction of the exogenous BpGLK gene had a specific effect on the abundance and diversity of rhizosphere bacterial and fungal communities in B. platyphylla. These changes can promote plant growth and enhance resistance. However, whether these effects persist over the long term remains to be confirmed in future experiments.
【Objective】 This research aims to investigate the growth and photosynthetic physiological characteristics of Acer truncatum seedlings in response to water-fertilizer coupling, and to analyze the optimal water-fertilizer combination for the growth of A. truncatum seedlings. 【Method】 One-year-old A. truncatum seedlings were subjected to varying water and fertilizer couplings in an orthogonal test design involving four factors and four levels of soil water content, nitrogen, phosphorus and potassium, resulting in 16 treatments. Growth indexes, relative chlorophyll content of the leaves SPAD values, photosynthetic characteristics, and light response curves were measured after the treatments. 【Result】 The growth indices generally increased firstly and then decreased with increasing fertilization amount. At a soil water content of 75%,1.2, 1.8 and 0 g/plant of N, P, K, respectively, the diameter and total biomass of the plant were significantly higher than those of other treatments. Suitable soil water and fertilizer coupling could significantly improve the height, ground diameter, and total biomass of A. truncatum seedlings. Moreover, there was no significant difference in the utilization ability of low light among different soil water and fertilizer coupling treatments, and nitrogen fertilizer had significant effects on the maximum net photosynthetic rate and light saturation point of A. truncatum seedlings. In addition, there was no significant difference in water use efficiency (WUE) between the different treatments for A. truncatum seedlings. The seedlings grew normally even under lower water conditions, such as 45% soil water content, and exhibited strong drought resistance. The effects of soil water and fertilizer on the growth of A. truncatum seedlings were ranked from high to low as nitrogen fertilizer > soil water content > potash fertilizer > phosphate fertilizer, based on a comprehensive scoring method. The optimal combination of water and fertilizer was 75% soil water content, with fertilizer comprising 1.2 g of nitrogen, 1.8 g of phosphorous, and 0 g of potassium per plant. 【Conclusion】 Water-fertilizer coupling had a significant effect on ground diameter and biomass of A. truncatum seedlings, but an insignificant effect on seedling height, while soil water content and nitrogen fertilizer also had a significant effect on the growth indexes of the seedlings. These findings provide a theoretical basis for the appropriate use of soil water and fertilizer in A. truncatum.
【Objective】Litter regression can affect the soil carbon and nitrogen cycle, which is an important process of sustainable management and soil fertility maintenance in Chinese fir(Cunninghamia lanceolata)plantations. The changes in soil carbon content, nitrogen content, and enzyme activity under the treatment of adding C. lanceolata and Schima superba litter were analyzed to provide the basis for nature-approximating transformation and stand management of C. lanceolata plantations.【Method】In the present study, 30-year-old C. lanceolata plantation soil was treated with C. lanceolata litter (S), S. superba litter (M), and a mixture of C. lanceolata and S. superba litter (mixed at a m (S):m (M)=5:1, SM). After 60 days of incubation, the content of ammonium nitrogen ( NH 4 +-N), nitrate nitrogen ( NO 3 --N), soil organic carbon (SOC), water soluble organic carbon (WSOC), hydrochloric acid hydrolyzed organic carbon (HHOC), alkaline-hydrolyzable organic carbon (AHOC), recalcitrant organic carbon (ROC), and enzyme activities (β-glucosidase(GC); β-N-acetylglucosaminidase(NAG); polyphenol oxidase(PPO); and leucine aminopeptidase(LAP)) in the soil were measured in the different treatments. The relationship among soil carbon content, nitrogen content, and enzyme activity in different treatments was analyzed, and the effects of different litter on soil carbon content, nitrogen content, and enzyme activity in C. lanceolata plantations were evaluated.【Result】The degree of humification in the soil treated with mixed litter was increased compared to the soils treated with either litter alone. In the single litter treatment, the degree of humification with S. superba treatment was low, and the proportion of soil recalcitrant organic carbon (ROC) was relatively higher. After 15 and 30 days of incubation, the soil GC, NAG and PPO enzyme activities with C. lanceolata litter were significantly higher than those with S. superba litter. The decomposition of mixed litter significantly improved soil GC and NAG enzyme activities. The results of redundancy analysis and correlation analysis showed that soil AHOC content was significantly positively correlated with soil GC enzyme activity. NAG enzyme activity was positively correlated with soil WSOC content and negatively correlated with NH 4 +-N content, while PPO enzyme activity was negatively correlated with NO 3 --N content and positively correlated with ROC and HHOC contents (P<0.01).【Conclusion】The addition of different litters significantly affects the soil carbon content, nitrogen content, and enzyme activity in C. lanceolata plantations. Compared to the addition of S. superba litter, the addition of C. lanceolata litter results in a higher soil humification degree, as well as higher enzyme activities related to the carbon and nitrogen cycle. Further, the addition of both C. lanceolata and S. superba litter is more beneficial in improving the degree of soil humification, soil carbon invertase activity, and nitrogen invertase activity compared to the addition of either litter alone, thus ultimately benefitting the soil carbon and nitrogen cycle of C. lanceolata plantations.
【Objective】The aim of the present study is to simulate the effects of long-term nitrogen (N) deposition on soil organic carbon (SOC) and organic carbon storage in subtropical forests with phosphorus (P) limitation to investigate the effects of active SOC and soil organic nitrogen (SON) components on organic carbon storage under long-term N addition, as well as to provide the basis for soil carbon (C) sequestration capacity and sustainable management of subtropical forest ecosystems.【Method】In an evergreen broad-leaved forest of Zhawan Nature Reserve, Qimen County, Anhui Province, two sites were selected, the middle slope and flat ridge, for the present study. Three different N and P addition treatments were designed at each site as follows: control (CK, N and P addition of 0 kg/hm2 per year), N addition (N, N addition of 100 kg/hm2 per year), and N+P addition (N+P, N addition of 100 kg/hm2 and P addition of 50 kg/hm2 per year). There were three replicate plots of 30 m × 15 m for each treatment, with a total of 18 sampling plots. In October 2020, soil samples were collected from the 0-40 cm layer in each plot to determine SOC content, SOC storage, active SOC fraction, SON fraction, and other basic physicochemical properties. The collected soil samples were divided into two parts. One part of the soil sample was naturally air-dried, crushed, and passed through a 0.25 mm sieve for the determination of soil SOC and total nitrogen (TN) content. The other part of the soil sample was treated differently to determine soil SOC, SON fraction, and other physicochemical properties to investigate the effect of long-term simulated N deposition on the organic carbon storage capacity of subtropical forest soils, as well as the effects of SOC and SON fractions on organic carbon storage. 【Result】Compared to the CK treatment, N and P additions did not significantly change the SOC content and storage, but it significantly reduced the soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) contents. Correlation analysis showed that SOC storage was significantly and positively correlated with most soil physical and chemical properties but significantly and negatively correlated with pH and bulk density. Linear regression analysis demonstrated that particulate organic carbon (POC) and particulate organic nitrogen (PON) explained 75.4% and 71.7% of the effects on SOC storage, respectively, while MBC and MBN explained 26.0% and 49.3% of the effects on SOC storage, respectively. There was no significant relationship between dissolved organic carbon (DOC) and SOC storage, and DOC explained 11.4% of the effects on SOC storage.【Conclusion】Long-term N and N+P additions significantly reduce the C and N contents of soil microbial biomass and may be detrimental to SOC stocks, with POC and PON having the greatest impact on SOC storage.
【Objective】The objective of this study is to investigate the nitrogen (N) and phosphorus (P) allocation patterns in the above- and below-ground organs of three different tree species in northeast China, namely Populus davidiana, Fraxinus mandshurica and Taxus cuspidata, and to provide theoretical insights into the trade-offs and allocation strategies of nutrient distribution among tree species.【Method】Mature individuals of P. davidiana, F. mandshurica and T. cuspidata were selected as research subjects. The N and P contents in aboveground organs, i.e., leaves, twigs and belowground organs, i.e., coarse roots, fine roots, were analyzed and the allocation ratios of N and P contents in the leaves, twigs and roots were calculated. Standardized major axis regressions were employed to examine the relationships of N and P elements between aboveground (belowground) organs of three tree species and the bidirectional nutrient transport of the same elements between aboveground and belowground organs.【Result】(1)The N and P contents in the leaves of P. davidiana and F. mandshurica were similar. However, the N and P contents in the leaves of these two species were significantly higher and lower, respectively, compared to T. cuspidata (P<0.05). The twigs of T. cuspidata exhibited the highest N and P contents, while F. mandshurica had the highest P content in coarse roots and N and P contents in fine roots. The N content in coarse roots was similar among the three species. (2)The ratios of N and P contents in leaves to twigs and leaves to coarse roots were the highest in F. mandshurica and P. davidiana, respectively, while the ratios of leaves to fine roots were the lowest in F. mandshurica. (3)For P. davidiana and T. cuspidata, the aboveground and belowground organs showed an allometric and isometric relationship respectively between N and P contents, with the scaling exponent in belowground being approximately half of that in aboveground. In contrast, F. mandshurica exhibited similar scaling exponents aboveground and belowground, both exhibiting significantly greater than 1 allometric relationship. For P. davidiana, the slopes of both aboveground and belowground P in both directions are half of the corresponding N values. For T. cuspidata, the slopes of P content in the upward direction were also half of the corresponding N values, and the downward N and P relationships were not significant. For F. mandshurica, the slopes of N and P content in the upward direction were similar, whereas in the downward direction, the P content slope was approximately 2/3 of N.【Conclusion】In contrast to P. davidiana and T. cuspidata, F. mandshurica tended to allocate N and P to metabolically active organs such as leaves and fine roots. The relationships between N and P in aboveground (or belowground) organs and N and P between above- and below-ground showed distinct coordinations for F. mandshurica compared to P. davidiana and T. cuspidata.
【Objective】 This study aims to comprehensively protect, rationally develop as well as effectively utilize natural scenic resources and alleviate the fragmentation, islanding and uneven distribution of natural resource landscapes in Jiangsu Province.【Method】 Using ArcGIS spatial analysis technology, the spatial distribution characteristics of natural landscape resources in Jiangsu Province were obtained from the Nearest Neighbor Index (NNI) and results of the kernel density analysis and accessibility analysis. Also, based on the double evaluation' of the land and space planning and the natural environment of Jiangsu Province, an ecological protection evaluation, including evaluations of the ecosystem services and ecological sensitivity, was conducted. Based on the evaluation results, the ecological space of Jiangsu Province was delineated. The above results are superimposed with the corresponding physical and human geographical characterizations of Jiangsu Province. 【Result】 The distribution and regional differences of protected areas of natural landscape resources in Jiangsu Province were revealed, which provided a realistic basis for the selection of natural landscape patches, corridors and advantageous regions. Nine natural landscape patches, seven natural landscape corridors and two natural landscape dominant areas in Jiangsu Province were delineated. Also, a natural landscape system in Jiangsu Province was formed based on natural landscape resources dominated by patches, corridors and substrates. 【Conclusion】 The landscape system applied the spatial concept to the study of landscape resources. This approach helps to strengthen the connection between protected areas of natural landscape resources, improve the integration and optimization of resources, create a landscape pattern more suitable for the protection and development of natural landscape resources in Jiangsu Province, and provide effective guidance for the protection and construction of natural landscape resources in Jiangsu Province and a scientific basis for reasonable development and utilization.
【Objective】The aim of the present study was to investigate the soil physical properties, chemical properties, and enzyme activities under different Carya illinoensis ‘Pawnee’ and Paeonia ostii ‘Feng Dan’ planting modes, as well as analyze the effects of different modes and seasons on soil characteristics.【Method】The treatments included single cultivation of C. illinoensis (mode Ⅰ), compound cultivation of C. illinoensis ‘Pawnee’-P. ostii ‘Feng Dan’ (mode Ⅱ), and single cultivation of P. ostii (mode Ⅲ). Seasonal variation of soil physical properties, chemical properties, and enzyme activities were measured under different modes, and the minimum date set method and soil integrated fertility index (IFI) were utilized to evaluate the changes of soil fertility.【Result】The nutrient and enzyme activity in the surface soil were higher than those in the deep soil. The soil moisture content and bulk density gradually varied with the seasons of spring, summer and autumn. There was no significant difference on soil pH between the spring and summer seasons, and the lowest soil pH was observed in autumn. The soil catalase activity in summer was higher than that in spring and autumn. The soil organic matter content, total nitrogen content, available potassium content, sucrase activity, and urease activity increased during the seasonal variation of spring, summer, and autumn. In mode Ⅲ, the soil available phosphorus content in autumn was higher than that in spring and summer. The seasonal variation of the soil IFI was the lowest in summer and highest in mode Ⅱ.【Conclusion】There is a correlation among soil physical properties, chemical properties and enzyme activities. The soil fertility of the compound cultivation of C. illinoensis ‘Pawnee’-P. ostii ‘Feng Dan’ (mode Ⅱ) is significantly higher than single cultivation of either species, and the soil fertility quality is lower in summer than in spring and autumn. The soil fertility quality is directly affected by bulk density, total nitrogen content, available potassium content, available phosphorus content, sucrase activity, and urease activity. Further, sucrase activity is more sensitive in evaluating the soil IFI in all seasons.
【Objective】Increased nitrogen (N) deposition affects carbon (C) and N availability by affecting the litter decomposition process, after which it affects the C-nutrient balance of the biogeochemical cycle. In this study, the nylon mesh bag method was used to study the decomposition rate and nutrient content changes of Quercus aquifolioides litter under simulated N deposition, providing a reference for an effective Q. aquifolioides forest ecosystem management.【Method】The in situ litter decomposition test was carried out in the Q. aquifolioides forest of Mopanshan in Xinping County, central Yunnan Province. Four N levels were applied using the nylon mesh bag method, with urea (CH4N2O) as the N source for in situ decomposition of litter and N deposition treatment. The four N deposition levels were: control [CK, 0 g/(m2·a)], low N [LN, 10 g/(m2·a)], medium N [MN, 20 g/(m2·a)] and high N [HN, 25 g/(m2·a)]. Leaf litter and twig mass remaining, lignin, cellulose, and C, N, P and K contents were then measured.【Result】① After one year of decomposition, the N deposition treatment significantly increased the mass remaining rate (P<0.05) of leaf litter (0.84%-3.87%) and twig (1.67%-3.30%). The litter decomposition was inhibited, and the inhibition intensity was proportional to N content application. ② Variation coefficients of leaf and twig litter decomposition were 0.271-0.368 and 0.167-0.218 kg/(kg·a), respectively. The lhe C/N (69.02) and lignin/N (54.65) of twig litter were significantly higher compared with leaf litter (52.09 and 44.42, respectively). Leaf decomposition rate was faster compared with that of twig. ③ The chemical composition of the litter affected its mass remaining rate, which was negatively correlated with N and P contents of leaf and twig litters, and positively correlated with C, cellulose, C/N, C/P, lignin/N and cellulose/N.【Conclusion】The N deposition inhibits litter decomposition, and this effect is significantly enhanced by increased nutrient content. Initial nutrient content effects nutrient retention and litter release processes, among which N level, C/N and lignin/N are important influencing factors.
