植物生态学报 ›› 2006, Vol. 30 ›› Issue (6): 894-900.DOI: 10.17521/cjpe.2006.0113

• 论文 • 上一篇    下一篇

极端干旱条件下锡林河流域羊草草原净生态系统碳交换特征

黄祥忠1(), 郝彦宾1,2, 王艳芬1,2,*(), 周小奇1, 韩喜3, 贺俊杰3   

  1. 1 中国科学院研究生院生物系,北京 100049
    2 中国科学院植物研究所植被数量生态学重点实验室,北京 100093
    3 内蒙古锡林郭勒盟牧业气象试验站,锡林郭勒 026000
  • 收稿日期:2006-03-31 接受日期:2006-06-22 出版日期:2006-03-31 发布日期:2006-11-30
  • 通讯作者: 王艳芬
  • 作者简介:* E-mail: yfwang@gucas.ac.cn
    E-mail: huangxiangz@mails.gucas.ac.cn
  • 基金资助:
    国家重点基础研究发展规划项目(2002cb412501)

IMPACT OF EXTREME DROUGHT ON NET ECOSYSTEM EXCHANGE FROM LEMUS CHINENSIS STEPPE IN XILIN RIVER BASIN, CHINA

HUANG Xiang-Zhong1(), HAO Yan-Bin1,2, WANG Yan-Fen1,2,*(), ZHOU Xiao-Qi1, HAN Xi3, HE Jun-Jie3   

  1. 1 Department of Biology, Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
    2 Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    3 Inner Mongolia Xilingole League Pasture Meteorological Research Station, Xilingole, Inner Mongolia 026000, China
  • Received:2006-03-31 Accepted:2006-06-22 Online:2006-03-31 Published:2006-11-30
  • Contact: WANG Yan-Fen

摘要:

采用涡度相关法对2005年生长季内蒙古锡林河流域羊草(Leymus chinensis)草原净生态系统交换(Net ecosystem exchange, NEE)进行了观测。观测结果表明:作为生长季降雨量仅有126 mm的干旱年,锡林河流域羊草草原生态系统受到强烈的干旱胁迫,其净生态系统碳交换的日动态表现为具有两个吸收高峰,净吸收峰值出现在8∶00和18∶00左右。最大的CO2吸收率为-0.38 mg CO2·m-2·s-1,出现在6月底,与丰水年相比生态系统最大CO2吸收率下降了1倍。就整个生长季而言,不管是白天还是晚上2005年都表现为净CO2排放,整个生长季CO2净排放量为372.56 g CO2·m-2,是一个明显的CO2源。土壤含水量和土壤温度控制着生态系统CO2通量的大小,尤其是在白天,CO2通量和土壤含水量的变化呈现出显著的负相关关系,和土壤温度表现为正相关关系。

关键词: 极端干旱, 涡度相关法, 净生态系统交换, 羊草草原

Abstract:

Background and Aims Many reports on global change have predicted major change in the temporal and spatial pattern of precipitation, which may have significant effects on temperate grasslands in arid and semi-arid regions. The responses of grasslands to environmental changes, especially amount and timing of precipitation, can be very different. Some studies indicate that drought may result in degradation of ecosystem function in NEE, even changing the ecosystem from a carbon sink to a carbon source.

Methods In order to quantify net ecosystem carbon exchange in Leymus chinensis steppe and its response to precipitation, we used the eddy covariance technique to measure carbon dioxide flux during the 2005 growing season in Xilin River Basin of Inner Mongolia Plateau in 2005. Only 126 mm precipitation fell during this growing season, far less than average; therefore, the steppe was in an extreme drought condition.

Key Results The daily pattern of CO2 uptake in this drought year was consistent bimodal, with peaks at 8∶00 and 18∶00. In normal years, the bimodal pattern occurred only when soil water stress occurred. Maximum half-hourly average CO2 uptake was -0.38 mg·m-2·s-1 in 2005, which was half that in typical growing seasons. Moreover, the ecosystem was a CO2 source most of the growing season, releasing about 0.05 mg CO2·m-2·s-1 at nighttime.

Conclusions The seasonal pattern of CO2 uptake closely followed that of aboveground biomass and was strongly affected by soil temperature and soil water content. The ecosystem emitted 372.56 g CO2·m-2 during the growing season in 2005. The partial explanation is that much plant litter accumulated on the ground surface due to enclosure of the grassland since 1979, and this litter decomposed and resulted in a net release of CO2 to atmosphere.

Key words: Extreme drought, Eddy covariance, CO2 flux, Leymus chinensis steppe