期刊
ECOLOGY
卷 98, 期 7, 页码 1779-1786出版社
WILEY
DOI: 10.1002/ecy.1878
关键词
arid grassland ecosystem; community stability; diversity; eutrophication; fluctuating limiting resource; mechanism; productivity; species composition
类别
资金
- University of Nebraska
- National Key (Basic) Research Program of China [2015CB150801, 2016YFC0500705]
- National Natural Science Foundation of China [31300410]
- Program for Introducing Talents to University [B16011]
- China Scholarship Council
Adding nutrients to nutrient-limited ecosystems typically lowers plant diversity and decreases species asynchrony. Both, in turn, decrease the stability of productivity in the response to negative climate fluctuations such as droughts. However, most classic studies examining stability have been done in relatively wet grasslands dominated by perennial grasses. We examined how nutrient additions influence the stability of productivity to rainfall variability in an arid grassland with a mix of perennial and annual species. Of the nutrients, only nitrogen increased productivity, and only in wet years. In addition, only nitrogen decreased the stability of productivity. Thus, nutrient addition makes ecosystem productivity less stable in both wet and arid grasslands. However, the mechanism is very different. In contrast to wet grasslands, adding nitrogen to an arid grassland did not decrease diversity. Rather, stability decreased with nitrogen addition due to an increase in annual species that increased productivity. In other words, in our arid grassland, nitrogen addition decreased ecosystem stability because of increased ecosystem responsiveness to positive climate fluctuations. These climate fluctuations were facilitated by annual species that take advantage of wet years and can escape dry years as seeds. Our data support the conclusion that nutrient additions decrease the stability of productivity in both wet and arid grasslands. Nutrient enrichment increases the sensitivity of productivity to low rainfall years in wet grasslands, whereas nutrient enrichment in arid grasslands increases the sensitivity of productivity to high rainfall years.
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