Zhou Z, Sun O J, Huang J, Gao Y, Han X
Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, and.
Graduate School of the Chinese Academy of Sciences, Beijing 100049, China.
Funct Ecol. 2006 Oct;20(5):753-762. doi: 10.1111/j.1365-2435.2006.01175.x. Epub 2006 Jul 25.
1The accelerating extinction rate of plant species and its effect on ecosystem functioning is a hotly debated topic in ecological research. Most research projects concerning the relationship between species diversity and productivity have been conducted in artificial plant communities, with only a few in natural ecosystems. In this study we examined the relationship between species diversity and above-ground net primary productivity (ANPP) over two consecutive growth seasons (2004 and 2005) in a semi-arid steppe ecosystem of northern China, that were subjected to different land uses.2Land use affected the relationship between species diversity and ANPP in this semi-arid steppe ecosystem. Exclusion of grazing without or with biomass removal by mowing increased ANPP, species richness and species diversity compared with free grazing; the effect was reflected mainly as enhanced importance of the perennial forbs functional group in terms of their relative contributions to ANPP, plant cover and plant abundance.3Many mechanisms regulate the relationship between species diversity and productivity. Differential effects of anthropogenic activities on biodiversity and ecosystem functioning greatly complicate the analysis of such relationships. On grazing-exclusion sites the relationship between ANPP and species richness can be best described as an exponential growth function ( = 0·99, < 0·001, = 24); whereas on the free-grazing site the relationship takes the form of exponential decay ( = 0·96, < 0·001, = 24). Our study concludes that the mode and severity of disturbance are important factors for interpreting the relationship between species diversity and productivity in semi-arid steppe ecosystems.
植物物种灭绝速率的加快及其对生态系统功能的影响是生态研究中一个备受争议的热点话题。大多数关于物种多样性与生产力关系的研究项目都是在人工植物群落中进行的，在自然生态系统中的研究较少。在本研究中，我们在中国北方半干旱草原生态系统中，连续两个生长季节（2004年和2005年）研究了不同土地利用方式下物种多样性与地上净初级生产力（ANPP）之间的关系。
土地利用影响了这个半干旱草原生态系统中物种多样性与ANPP之间的关系。与自由放牧相比，不放牧或刈割去除生物量的禁牧措施增加了ANPP、物种丰富度和物种多样性；这种影响主要体现在多年生草本功能群对ANPP、植被覆盖度和植物丰度的相对贡献方面的重要性增强。
许多机制调节着物种多样性与生产力之间的关系。人为活动对生物多样性和生态系统功能的不同影响极大地复杂化了这种关系的分析。在禁牧样地，ANPP与物种丰富度之间的关系可以最好地描述为指数增长函数（r = 0·99，P < 0·001，n = 24）；而在自由放牧样地，这种关系呈指数衰减形式（r = 0·96，P < 0·001，n = 24）。我们的研究得出结论，干扰的方式和强度是解释半干旱草原生态系统中物种多样性与生产力关系的重要因素。
