石漠化区植物-土壤C、N、P化学计量特征及其对非生物环境因子的响应

At present, people mainly judge the evolution and developing trend of rocky desertification by the rate of exposed bedrock, soil area, slope and vegetation coverage, but can't judge by the material composition and its dynamic characteristic inside the rocky desertification system, which is not propitious for people to understand the intrinsic characteristics of rocky desertification, as a result, it has a huge influence on the result of harness rock-desertification. Basing on element balance, ecological mutual effect theory and homeostasis theoretical model of ecological stoichiometry, the project take different rocky desertification degree sample lands as experimental platform and make the following research: the C, N, P correlation ratios and dynamic characteristics among soil-litter-root-stem-leaf from different rocky desertification degree sample lands; species level stoichiometric homeostasis variability of plants and its relationship with rocky desertification system composition, function and stability; C, N, P stoichiometric rattios in plant-soil system and their response to abiotic environmental factors. The purpose of our study is to find out C, N, P stoichiometric rattios stability, variation mechanism and its relation to abiotic environmental factors in plant-soil system in rokcy desertification area. The results of our research will reveal the inside characteristic of rocky desertification from material composition and its dynamic characteristic perspective, which could provide a more scientific method for judging the evolution and developing trend of rocky desertification, and offer a better reference for making policy to control it.

目前，国内对石漠化的演变规律及发展趋势主要根据基岩裸露率、土被面积、坡度、植被盖度等表象特征进行判别，未能从石漠化系统内部的物质组成及其动态特征进行预测，不利于人们对石漠化内在特征的认识，极大地影响了石漠化的治理。本项目以生态化学计量学的元素平衡、生态交互作用以及内稳性理论模型为指导，以不同石漠化程度样地为实验平台，开展以下研究：不同石漠化程度样地土壤－凋落物－根－茎－叶的C、N、P比值相关性及其动态特征；植物物种水平化学计量学内稳性变异特征与石漠化系统结构、功能和稳定性的关系；石漠化植物－土壤系统C、N、P化学计量比对非生物环境因子的响应。将阐明石漠化系统植物－土壤C、N、P化学计量的稳定性及变异机制及其与非生物环境因子的关系，从物质组成比率关系及其动态变化角度揭示石漠化环境退化的内在特征。研究结果将更科学地对石漠化演变规律及发展趋势进行预测，为石漠化的治理规划提供更为有效的参考依据。

项目针对目前对我国西南岩溶地区主要以基岩裸露率、土被面积、坡度、植被盖度等表象特征判别石漠化演变规律及其发展趋势存在的不足，利用生态化学计量学的元素平衡、生态交互作用以及内稳性理论模型为指导，在我国西南典型岩溶石漠化区选择典型研究区，开展以下研究：不同程度石漠化样地土壤—凋落物—根—茎—叶的C、N、P比值相关性及其动态特征；植物物种水平化学计量学内稳性及其变异特征与石漠化系统结构、功能和稳定性关系；石漠化植物—土壤系统C、N、P化学计量比对非生物环境因子的响应；计算碳酸盐岩石灰土土壤不同形态N库的转化速率，研究石灰土N循环及迁移特征。通过四年的研究，获得以下主要进展：（1）初步阐明了石漠化系统植物-土壤C、N、P化学计量的稳定性和变异机制及其与非生物环境因子的关系，从物质组成比例关系及其动态变化角度揭示了石漠化环境退化的内在特征；（2）揭示了喀斯特峰丛洼地受放牧干扰下石漠化样地C、N、P化学计量学特征，从生态化学计量学的角度阐述了放牧影响下石漠化正向演变与逆向演变植物-土壤系统C、N、P含量及其比值变化特征；（3）对岩溶区和非岩溶区土壤碳氮磷生态化学计量特征及其空间分布进行了对比分析，认为成土母质和土壤类型等自然因素严重制约了岩溶石漠化区土壤碳氮磷的空间分布并导致其分异；（4）采用同位素双标记方法并结合MCMC优化数值模型，研究了碳酸盐岩石灰土N元素的循环及迁移转化特征，认为岩溶石漠化区土壤总无机N供应能力低下且极易进入岩溶水中流失掉，即使退耕还林还草后，石漠化区土壤中的无机N供应能力和利用性仍然处于较低水平。项目所获得的进展和研究结果、实验数据等将更科学地对石漠化演变规律及其发展趋势进行预测，为石漠化的治理规划提供更为有效的科学参考依据。