Authors: Changhui Wang Klaus ButterbachBahl Yi Han Qibing Wang Lihua Zhang Xingguo Han Xuerong Xing
Publish Date: 2010/10/20
Volume: 340, Issue: 1-2, Pages: 397-411
Abstract
There is an increasing demand for the sustainable management of oldfield communities in northern China which have developed on abandoned cropland on formerly converted natural steppe sites to regain forage yield biodiversity and soil fertility In thus study we examined how two management options—clipping and nitrogen N addition—may affect net microbial N mineralization ammonification + nitrification microbial biomass carbon MBC microbial biomass nitrogen MBN and microbial respirations MR in grass dominated herb dominated and grassherb mixed patches in an oldfield community in northern ChinaTopsoil 0–10 cm net N mineralization rate was 177 and 69 higher in mixed grass and herb patches patch B as compared to unmixed grass patch A or herb patch C patches respectively Topsoil MBN was significantly different among the three patches with the highest value for soils taken from umixed grass patches However patches with mixed grass and herb or herb dominated patches had 12 higher microbial respiration MR than unmixed grass patch Clipping and N addition had no effects on net N mineralization or MBC but both treatments decreased MBN and MR and increased the ratio between microbial biomass C and microbial biomass N MBC/MBN in the growing season Incubation of soil cores under optimal water and temperature conditions in the laboratory showed that the response of microbial N transformations in soils under different vegetation patches to experimental N addition and clipping was limited by soil water availability Our results strongly highlight the need to further study the importance of belowground C supply as a control of microbial N cycling processes It also suggests that during the restoration process of degenerated croplands N cycling rates are stimulated but that the magnitude of this stimulation is modulated by plant community composition of the oldfieldsThis research was financially supported by the State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences and the Ministry of Science and Technology of China 2007CB106801 We wish to extend our thanks to the staff of the Duolun Restoration Ecology Experimentation and Demonstration Station We are also grateful to Jianyang Xia Zhe Zhang Haijun Yang and Delu Lin for their assistance in collecting samples and to Feng Zhu Yanbo Yu and Lina Niu for help in laboratory measurements We also thank two anonymous reviewers of the original manuscript for constructive comments
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