关键词: 林龄, 马尾松, 叶功能性状, 土壤养分, 针叶, 喀斯特地区

Abstract:

【Objective】 Plant functional traits, termed as morpho-physio-phenological traits, are a bridge between plants and their environmental factors, which link plants and environmental structures, processes and functions, reflecting the responses and adaptations of plants to the environment.Variation in leaf functional traits is an important strategy used by plants to respond and adapt to changes in environmental conditions. On the basis of various leaf functional traits of different-agedPinus massoniana communities as well as the relationships between the traits and soil nutrients, the adaptation strategy of P. massoniana in relation to soil conditions was analyzed in the Karst environment, which provided a scientific basis for better development of P. massoniana plantations in the Karst area. 【Method】 In the present study, experiments were carried out at nine sampling points along an age gradient (14, 26 and 33) in P. massoniana plantations in the northwestern region of Guizhou Province. Three fixed sample plots of 20 m × 30 m were established for each community type. In each sample, five strains of P. massoniana with good growth and without pests and diseases were randomly selected, and 200 bundles of needles were collected per plant to measure the functional traits. The leaf functional traits (leaf thickness, leaf area, leaf dry matter content, specific leaf area, leaf organic C content, leaf total N content, and leaf total P content) and soil nutrients (soil organic matter, soil total nitrogen, soil available nitrogen, soil total phosphorus, soil available phosphorus) in different-aged communities were measured. Pearson correlation analysis and stepwise regression analysis were used to study the relationship between the different leaf functional traits of species in the different-aged communities and soil nutrients. 【Result】 Among the eight leaf functional traits, the smallest coefficient of variation was observed forw(OC), and the largest was observed for specific leaf area ($S_{SLA}$). In addition to $S_{SLA}$ and leaf area (S_LA), other leaf functional traits were weakly variable. With increasing stand age, $S_{SLA}$, S_LA, T_L, L_L/D_L, w(TP), w(TN), and w(OC)increased andw(LDM) decreased. Pearson correlation analysis showed that L_L/D_L was significantly positively correlated with S_LA and w_LTP and positively correlated with T_L; T_L was significantly positively correlated with S_LA, S_SLA, w(OC), w(TN),and w(TP); S_LA was significantly positively correlated with S_SLA, w(OC), w(TN),and w(TP); w(LDM)was significantly negatively correlated with L_L/D_L, T_L, S_LA, S_SLA, w(OC), w(TN),and w(TP); S_SLA was significantly positively correlated with w(TN)and w(TP) and was positively correlated withw(OC); w(OC)was positively correlated with w(TN)and w(TP); and w(TN)was significantly positively correlated with w(TP). These results indicated that P. massoniana was capable of changing the leaf morphological structure to adapt to environmental changes. The soil organic carbon content, total nitrogen content, total phosphorus content, available nitrogen content, and available phosphorus content in P. massoniana plantations showed an increasing trend with increasing stand age, and the change in stand age had a significant effect on these characteristics. Soil total phosphorus content was the main factor affecting L_L/D_L, T_L, S_LA, w(LDM), $S_{SLA}$ and w(TP), whereas soil organic carbon content mainly affected w(LDM), w(TP) and w(TN). Therefore, soil total phosphorus and organic carbon content were the main factors that affected the leaf functional traits of P. massoniana in different-aged stands. 【Conclusion】 Soil nutrients in P. massoniana communities were improved with increasing stand age, which eventually affected leaf functional traits. The flexibility of leaf functional traits indicated that P. massoniana communities had great potential to adapt to environmental changes in the Karst region through the combination of functional traits. The response of functional traits to soil physicochemical properties is an elaborate process; we need to monitor their response over long term and conduct further research.

Key words: stand age, Pinus massoniana, leaf functional trait, soil nutrient, needle, Karst region