高寒矮嵩草草甸物种多样性与功能多样性对初级生产力的影响

Effects of species diversity and functional diversity on primary productivity of alpine meadow

自然生态系统中植物物种多样性是否随功能多样性变化而影响初级生产力的问题存在很大争议。在高寒矮嵩草草甸,对不同放牧强度、不同利用格局和土壤资源水平的4种生境(Ⅰ.畜圈:重度放牧、资源丰富;Ⅱ.牧道:中度放牧、资源适中;Ⅲ.人工草地:轻-中度放牧、资源贫乏;Ⅳ.封育草地:不放牧、资源贫乏)中物种多样性与功能多样性的变化及其对初级生产力的影响进行了研究。结果表明:物种多样性在牧道生境最高,符合中度干扰理论的预测;人工草地物种多样性低但功能多样性却最高;封育草地物种多样性和功能多样性均较高;物种多样性与地上生物量呈正相关,而功能多样性则与地上生物量呈负相关。表明功能多样性不随物种多样性而变化,二者可能在一定程度上是相互独立地作用于生产力的。群落生产力和生物多样性受生境资源、物种特征、放牧历史和放牧强度等因素的综合影响。

Whether the species diversity （SD） in natural ecosystem varies with functional diversity （FD） and consequently affects the primary productivity is still an open question. In this paper, a field grazing experiment was conducted on an alpine Kobresia humilis meadow to study the effects of SD and FD on the primary productivity of the ecosystem. Four habitats with different grazing intensity and soil nutrient availability were selected, i. e. , pen pasture with heavy grazing intensity and highest nutrient availability, pass pasture w. ith moderate grazing intensity and moderate nutrient availability, artificial pasture with light-moderate grazing intensity and lower nutrient availability, and un-grazed pasture with null grazing intensity and lowest nutrient availability. Among the test habitats, pass pasture had the highest SD, which fitted intermediate disturbance hypothesis. Artificial pasture had low SD but the highest FD, while un-grazed pasture had higher SD and FD. There was a positive relationship between SD and primary productivity but a negative relationship between FD and primary productivity, suggesting that FD didn＇ t vary with SD, and, to a definite extent, both SD and FD could affect the primary ：productivity independently. Habitat resources, species characteristics, grazing history, and grazing intensity affected the community＇s primary productivity and biodiversity in an integrative way.