Abstract:

【Objective】The Luoshan Mountains in the Ningxia Hui Auto nomons Region are unique ecological security barriers in the arid zone of central China. Therefore, the stoichiometric characteristics of this area’s forest ecosystems were studied to describe the limiting nutrients during vegetation development, to provide a theoretical basis for community selection and forest management in this area.【Method】Spruce (Picea crassifolia) forests, Chinese pine (Pinus tabuliformis) forests, aspen (Populus davidiana) forests, and Picea crassifolia × Pinus tabuliformis mixed forests were examined for carbon (C), nitrogen (N) and phosphorus (P) contents of plant, litter, and soil, and plant-litter-soil ecological stoichiometry correlations were analyzed.【Result】(1) C content of leaves and branches were significantly higher compared with roots, the N and P contents of leaves were significantly higher compared with branches and roots, and leaf C/N was significantly lower compared with branches and roots. Furthermore, leaf and branch N content in Populus davidiana forests were significantly higher, and root N content in Pinus tabuliformis forests were significantly lower, compared with other forests. (2) Litter N, P content, and N/P in Populus davidiana forests were significantly higher, and C/N and C/P were significantly lower, compared with other forests. (3) Soil C, N, P content, C/N, and C/P did not differ significantly among forests, while soil N/P in Picea crassifolia forests was significantly higher than in other forests. (4) Plant N content was significantly positively correlated with litter N content and N/P, and significantly negatively correlated with litter C/N. Plant C/N was significantly positively correlated with litter C content, and strongly negatively correlated with litter N/P. Soil C/N and N/P were significantly positively correlated with plant P content and litter C/P, and significantly negatively correlated with plant C/P. The plant P content was significantly positively correlated with soil pH. Altitude was significantly positively correlated with litter C/N and C/P, and significantly negatively correlated with N content and N/P. Soil N/P was significantly negatively correlated with pH, and significantly positively correlated with altitude and N content. Soil C, N, P content, C/N, and C/P were significantly positively correlated with organic C content.【Conclusion】The plant growth and litter decomposition were both limited by N in the four main forest communities of the Luo Mountains, especially within the coniferous forests. Hence, the protection and use of N elements should be strengthened in these areas. The growth rate is the fastest and litter decomposes more easily in Populus davidiana forests, which are thus candidates for protection and vegetation restoration across the Luoshan Mountains.

Key words: ecological stoichiometry, plant, litter, soil, Luoshan Mountains National Nature Reserve, Ningxia