中国农业科学 ›› 2020, Vol. 53 ›› Issue (13): 2757-2768.doi: 10.3864/j.issn.0578-1752.2020.13.022

• 生态产业示范及区域尺度分析 • 上一篇    

北方草地及农牧交错区草地植被碳储量及其影响因素

辛晓平1(),丁蕾1,程伟1,朱晓昱1,陈宝瑞1,刘钟龄2,何广礼3,青格勒1,杨桂霞1,唐华俊1   

  1. 1中国农业科学院农业资源与农业区划研究所/呼伦贝尔草原生态系统国家野外科学观测研究站,北京 100081
    2内蒙古大学生态与环境学院,呼和浩特 010021
    3锡林郭勒职业学院草原生态与畜牧业学院,内蒙古锡林浩特 026000
  • 收稿日期:2019-09-23 接受日期:2020-02-19 出版日期:2020-07-01 发布日期:2020-07-16
  • 通讯作者: 辛晓平
  • 基金资助:
    国家重点研发计划(2016YFC0500600);国家重点研发计划(2017YFE0104500);国家自然科学基金(41771205);现代农业产业技术体系建设专项资金(CARS-34)

Biomass Carbon Storage and Its Effect Factors in Steppe and Agro-Pastoral Ecotones in Northern China

XIN XiaoPing1(),DING Lei1,CHENG Wei1,ZHU XiaoYu1,CHEN BaoRui1,LIU ZhongLing2,HE GuangLi3,QING GeLe1,YANG GuiXia1,TANG HuaJun1   

  1. 1Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences/National Hulunber Grassland Ecosystem Observation and Research Station, Beijing 100081
    2Department of Environmental Sciences, Inner Mongolia University, Huhhot 010021
    3Department of Grassland Ecology and Animal Husbandry, Xilingol Vocational College, Xilinhot 026000, Inner Mongolia
  • Received:2019-09-23 Accepted:2020-02-19 Online:2020-07-01 Published:2020-07-16
  • Contact: XiaoPing XIN

摘要:

【目的】 草地生态系统在全球碳平衡中有重要的意义,草地植被碳库及其变化机制研究是植被生态学的重要命题。本文研究北方草地和农牧交错区草地植被碳密度及其空间格局,解析不同区域草地植被碳密度的关键影响因素,分析了气候、土壤、放牧等因素对地上地下植被碳库的相对贡献。【方法】 基于2002—2009年北方草地及农牧交错带草地植被调查数据,结合同期MODIS/NDVI遥感影像和1﹕100万草地类型图,建立了我国主要草地类型的生物量估算模型;整合野外考察数据和前人研究结果,探讨了研究区地上地下生物碳库及其空间格局;基于研究区255个县级行政单元,分析了不同类型草地植被碳库与气候要素、土壤要素及家畜承载量的关系,应用一般线性模型(GLM)解析了不同影响因素对草地碳密度的相对贡献。【结果】 (1)北方草地与农牧交错区草地地上平均生物碳密度为36.9 g C·m-2,地下生物碳密度为362.9 g C·m-2,地下生物碳密度高于地上10倍,均呈从东到西递减的趋势,频率分布图基本服从对数正态分布,不同草地类型的生物碳密度存在明显差异;(2)整个研究区及草原亚区、荒漠亚区、农牧交错亚区内,地上生物量与年降水量(MAP)呈极显著正相关、与年均气温(MAT)均呈极显著负相关,与土壤黏粒含量(Clay%)呈显著正相关、与土壤砂粒含量(Sand%)呈显著负相关,整个研究区家畜承载量与草地地上生物量之间呈极显著正相关;(3)一般线性模型(GLM)分析结果表明,年平均降水量(MAP)、年均气温(MAT)、土壤黏粒含量(Clay%)、放牧强度对地上生物量空间变异的解释率分别达到29.6%(P<0.001)、5.8%(P<0.001)、0.8%(P<0.05)、1.3%(P<0.001);地下生物量的空间变异主要来自于年降水量(MAP)、年均气温(MAT)、土壤砂粒含量(Sand%),对方差的解释率分别达到12.1%(P<0.001)、6.8%(P<0.001)、1.9%(P<0.005),放牧强度没有明显贡献。【结论】 气候条件尤其是年降水量是草地生物量碳库的主要影响因素,但对地上生物量影响更为明显;土壤质地对植被生物碳库也有显著贡献,尤其对地下生物量的影响更加显著;放牧强度只能解释地上生物量变化的1.3%、对地下生物量没有显著贡献,这一发现意味着气候对生物量碳库的贡献远大于放牧影响。

关键词: 北方草地及农牧交错区, 植被碳储量, 气候因素, 家畜承载量, 土壤质地

Abstract:

【Objective】 The grassland ecosystem plays an important role in the global carbon balance. The study of grassland carbon pool and its driving force is a hot point of vegetation ecology. This study investigated the vegetation carbon density and its spatial pattern in the steppe and agro-pastoral ecotones of northern China. The major factors driving the spatial variation of grassland vegetation carbon density were identified, as well as the relative contribution of climate, soil texture, grazing intensity and other factors to the grassland vegetation carbon pool. 【Method】 Using the survey data of the grassland vegetation in northern grassland during 2002 and 2009, combined with the MODIS/NDVI remote sensing data and 1:1 million grassland type map, the estimation model of above- and below-ground biomass in the main grassland types of northern China was established. Based on 255 county-level administrative units in the study area, the relationship between grassland vegetation carbon density and climate factors, soil texture and livestock carrying capacity were explored, and derived the relative contribution of different driving factors to grassland carbon density using the general linear model (GLM). 【Result】 (1) The average above-ground biomass (AGB) of the steppe and agro-pastoral ecotones of northern China was 36.9 g C·m-2, and the below-ground biomass (BGB) was 362.9 g C·m-2, nearly 10 times the AGB. Both the above- and below-ground biomass decreased from east to west, and followed logarithmic normal distribution. The biomass carbon density of grassland types was significantly different. (2) In the whole study region and steppe sub-region, desert sub-region, agro-pastoral sub-region, the AGB showed a significantly positive correlation with mean annual precipitation (MAP) and soil clay content (Clay%), a significantly negative relationship with the mean annual temperature (MAT) and soil sand content (Sand%). The AGB increased with livestock carrying capacity except in the steppe sub-region where were very heavily grazed. (3) General Linear Model (GLM) analysis indicated that the MAP, MAT, Clay% and grazing intensity explained 29.6% (P<0.001), 5.8% (P<0.001), 0.8% (P<0.05) and 1.3% (P<0.001) of AGB variation, respectively, and the MAP, MAT and Sand% contributed to 12.1% (P<0.001), 6.8% (P<0.001) and 1.9% (P<0.005) to BGB variation, respectively, and the grazing intensity had minor contribution to BGB. 【Conclusion】 Climate factors especially MAP was the dominate driving factor of grassland vegetation carbon density, and its impact on AGB was more obvious than on BGB. Soil texture also had a significant contribution to the grassland vegetation carbon density, especially on the BGB. Grazing intensity explained only 1.3% of the AGB and had no impact on BGB. This finding indicated that the climate factors were major contributor grassland vegetation carbon density comparing with grazing intensity.

Key words: steppe and agro-pastoral ecotones in northern China, biomass carbon storage, climate, livestock capacity, soil texture