期刊
SOIL BIOLOGY & BIOCHEMISTRY
卷 42, 期 2, 页码 376-378出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.soilbio.2009.11.003
关键词
Dissolved organic nitrogen; Nitrate; Semiarid ecosystem; Biological soil crusts
类别
资金
- Spanish MICINN (co-funded by the European Social Fund) [CCL2008-00986-E/BOS]
- British Ecological Society [ECPG 231/607]
- BBVA Foundation [BIOCON06/105]
It has been suggested that the dominance of N forms should shift from dissolved organic nitrogen (DON) to nitrate along a gradient of increasing N availability. We aimed to apply this model at a local scale within a semi-arid ecosystem showing a high spatial heterogeneity in the distribution of vegetation and soil resources. By doing this, we seek a better understanding of the N cycling in spatially heterogeneous ecosystems. We took soil samples from the three major sources of spatial heterogeneity: the grass Stipa tenacissima, the N-fixing shrub Retama sphaerocarpa, and open areas. We also sampled the biological soil crust (BSC) located in the latter areas as another source of spatial heterogeneity. BSC microsites were classified by four levels of soil coverage, ranging from high coverage (66%) to bare soil. The proportion of nitrate, ammonium and DON was determined in all microsites. DON was the dominant N form for open areas, while nitrate was dominant under the canopy of Retama; these microsites contained the lowest and highest N availability, respectively. Under BSC, DON was the dominant N form. We found high temporal variability in the dominance of N forms for all microsites. Our results suggest that the biomederived model of Schimel and Bennett (2004) explaining N form dominance across N availability gradients may be extended to local gradients. (C) 2009 Elsevier Ltd. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据