Chin J Plan Ecolo ›› 2017, Vol. 41 ›› Issue (9): 938-952.DOI: 10.17521/cjpe.2017.0056

• Research Articles • Previous Articles     Next Articles

Effects of precipitation intensity and temporal pattern on soil nitrogen mineralization in a typical steppe of Nei Mongol grassland

Zhi-Cheng ZHU1,2, Yin HUANG1,2, Feng-Wei XU1,2, Wen XING1,2, Shu-Xia ZHENG1,*(), Yong-Fei BAI1   

  1. 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China
    and
    2University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2017-03-09 Revised:2017-06-01 Online:2017-09-10 Published:2017-10-23
  • Contact: Shu-Xia ZHENG

Abstract:

Aims Our objective is to: 1) explore the dynamics of soil nitrogen (N) mineralization in a grassland ecosystem in response to the changes in precipitation intensity and temporal distribution, and 2) identify the controlling factors.Methods The two study sites located in a typical steppe of the Nei Mongol grassland were fenced in 2013 and 1999, respectively. Our field experiment includes manipulations of three levels of precipitation intensity (increased 50%, decreased 50%, control) in three temporal patterns (increased or decreased precipitation for three years; increased or decreased precipitation for two years and no manipulation for one year; increased or decreased precipitation for one year and no manipulation for one year).Important findings 1) The soil net N mineralization and net nitrification rates decreased with changes in the temporal distributions of precipitation from one year to three years, with the maximum values of soil net N mineralization and nitrification rates observed in the treatments of increased or decreased precipitation for one year and no manipulation for one year (+PY1 or -PY1). This indicates that the high precipitation intensity and longer precipitation may have negative effects on soil net N mineralization and nitrification rates, while the moderate soilmoisture and temperature may stimulate soil mineralization. 2) The soil net N mineralization and nitrification rates, soil cumulative N mineralization, and nitrification in the fenced site in 1999 were higher than those in the site fenced in 2013, implying that a long-term enclosure may have promoted nutrient storage and soil quality restoration. 3) The long-term treatments of increased or decreased precipitation had significant effects on soil water content and temperature, whereas the short-term, discontinuous precipitation produced minor effects on soil moisture and temperature. Moreover, the controlling factors for soil N mineralization were different between the two fields. Soil moisture had a major effect on soil inorganic N content and net N mineralization rate in the site fenced in 2013, while soil temperature played a dominant role in the site fenced in 1999, with the net N mineralization rate depressed by higher soil moisture. Our findings suggest that the precipitation intensity and temporal distribution had important impacts on soil N mineralization in the Inner Mongolia grassland; these effects was site-dependent and particularly related to soil texture, community composition, and disturbance, and other factors.

Key words: precipitation intensity, precipitation temporal distribution, soil N mineralization, soil water content, soil temperature, Leymus chinensis steppe, fenced site