黄土丘陵区刺槐沙棘混交林种间养分协调机制研究

黄土丘陵区人工林因树种单一、结构简单导致生态系统稳定性差和生态服务功能衰退等问题已十分突出。营造混交林是人工林发展的必然趋势，但种间对资源分配和利用不同致使混交效果存在多样性和不确定性。在混交林种间多重关系中，对养分关系的研究有助于从更深层次阐释混交林资源高效利用和生态功能提升的机制。本研究在样地调查和采样分析的基础上，结合土钻、分解袋等方法，以陕北黄土丘陵区刺槐和沙棘纯林为对照，着重研究不同混交比例刺槐沙棘混交林生态系统的生物量及养分积累、分配和循环规律、根系分布空间特征、细根生产力和周转、叶片和细根养分内循环、细根和凋落物分解和养分释放及相互作用等；阐明黄土丘陵区刺槐沙棘混交林种间养分互补利用特征和影响因素；揭示细根和凋落物在混交林种间养分获取、利用和循环中的生态协调机制。该项目有利于深入认识混交植物对生长环境变化的适应性策略，为黄土丘陵区人工混交林营造和可持续经营提供科学依据。

The large-area plantations in the loess hilly region, maily due to single tree species, result the instability ecosystem and the declining of ecosystem services. Mixed plantations, as one of approaches to overcome many disadvantages of artificial pure plantations, can achieve the sustainability of plantation management. However, the diversity and uncertainty of mixed effects mainly due to the diverse of resources distribution and utilization. The research on the interspecies nutrients relationship，as one of important interspecific interactions in mixed plantations, can helpe to comprehensive understand the mechanisms of high resource using rate and ecosystem services upgrade in mixed plantations. The field investigation and sample chemical analysis methods in this current pending project, with combining soil soil auger and litter bag methods, as comparision with pure Black locust and Seabuekthorn plantations in the loess hilly region, to emphasis the biomass and the accumulation, distribution and cycling of nutrients in mixed Black locust and Seabuekthorn plantations with different mixed proportion, also considering the distribution patterns of root systems, fine roots productivity and turnover rate, internal nutrient cycling of fine roots and leaves, decomposition and nutrient release of fine root and leaf litter and their interactions. It is to clarify the characteristic processes and the main influence factors on the nutrient relationship between Black locust and Seabuekthorn in the mixed plantations，to reveal the coordinate mechanism of fine roots and leaf litter on nutrient acquisition, utilization and recycling between Black locust and Seabuekthorn in the mixed plantations. This project can provide new insights on the adaptation strategy of mixed plants to the change of growth conditions, and to provide a theoretical basis for the reconstruction and sustainable management of mixed vegetation restoration in the loess hilly region.