摘要
关于资源添加导致草地物种多样性丧失的模式能够被诸多竞争假说(光竞争假说、生态位维度-多样性假说、氮损害假说、凋落物假说)予以解释。然而,针对不同资源添加类型和数目驱动的物种多样性丧失机制是单独的还是协同的却鲜有研究。为了回答这一问题,以青藏高原甘南高寒草甸为对象,构建不同类型(氮、磷、钾)和数目(0/1/2/3)的资源添加处理,对物种多样性丧失的4种机制进行综合探讨。结果表明:1)相较于对照,氮素添加显著增加了植物地上净初级生产力,减小了物种丰富度,而磷或钾添加则无显著变化;2)氮素添加和资源添加数目都对物种丰富度减小产生直接负效应,这与生态位维度-多样性假说和氮损害假说所蕴含的地下土壤竞争机制有关;3)在氮素添加和资源添加数目处理下,植物地上净初级生产力的增加所引起光照可利用性减小都间接导致物种丰富度的减小,这与地上光竞争假说预测相符。综上,无论在资源类型(氮元素)还是资源添加数目处理下,生态位维度-多样性假说、氮损害假说和光竞争假说所体现的地上和地下多种竞争机制具有驱动草地物种多样性丧失的可能性,研究结果将为高寒草甸物种多样性的维持和保护提供具有可供参考的生态学理论依据。
The patterns of species diversity loss upon resource addition in grassland communities can be explained by several competitive hypotheses,including the light competition hypothesis,the niche dimensionality-diversity hypothesis,the nitrogen detriment hypothesis,and the litter hypothesis.Nevertheless,few studies have explored whether the mechanism of species diversity loss can be attributed to the type and number of added resources.To address this question,we conducted a field experiment with different numbers(0,1,2,and 3)and types(nitrogen,phosphorus,and potassium)of added resources,with the aim of exploring the four mechanisms of species diversity loss in an alpine meadow of Gannan on the Qinghai-Tibet Plateau.The results yielded the following findings:1)Compared with the control,nitrogen addition resulted in a notable increase in aboveground net primary productivity,and a reduction in species richness.However,neither phosphorus addition nor potassium addition significantly affected these variables.2)Both nitrogen addition and the number of added resources had a direct negative impact on species richness.This was related to belowground soil competition that underlies the niche dimension-diversity hypothesis and the nitrogen detriment hypothesis.3)As plant aboveground net primary productivity increased,light limitation became more intense,and this indirectly led to the loss of species richness,consistent with the aboveground light competition hypothesis.In conclusion,our results indicate that,with the addition of nitrogen or a number of added resources,aboveground and belowground ecological mechanisms act synergistically to drive losses in grassland species diversity,consistent with the multiple competition hypothesis.The findings of this study can serve as a basis for the formulation of an ecological theory that will contribute to the long-term maintenance and conservation of grassland species diversity in alpine ecosystems.
作者
王瑞兵
陈欢
潘珍珍
赵维
蚌绍豪
周小龙
任正炜
Rui-bing WANG;Huan CHEN;Zhen-zhen PAN;Wei ZHAO;Shao-hao BANG;Xiao-long ZHOU;Zheng-wei REN(College of Ecology and Environment,Xinjiang University,Urumqi 830017,China;Key Laboratory of Oasis Ecology,Xinjiang University,Urumqi 830017,China;College of Ecology,Lanzhou University,Lanzhou 730000,China)
出处
《草业学报》
北大核心
2025年第5期1-11,共11页
Acta Prataculturae Sinica
基金
国家自然科学基金(32060285)资助。
关键词
光竞争
生态位维度
氮损害
物种丰富度
高寒草甸
light competition
niche dimension
nitrogen detriment
species richness
alpine meadow
