Abstract: Grassland ecological system is an important component in the land ecological system, which played an important role in the global carbon cycle. This paper analyzed the spacial distribution pattern of natural grassland biomass of different vegetation types and its influencing factors in Shaanxi province, based on the 57 survey samples of the above- and belowground biomasses and litter biomasses, in order to provide some basic data for grassland ecological system carbon research in China. The results showed that every part of biomass in 7 kinds grass types, including warm-temperate hassock, warm-temperate hassock with shrubs, temperate mountain meadow, temperate meadow, temperate steppe, temperate desert steppe and low-land salinized meadow, were varied significantly (P<0.05). Their aboveground biomasses were 238.3, 293.6, 157.0, 350.5, 156.9, 99.9 and 144.6 g穖^-2,respectively; belowground biomasses were 670.2, 560.5, 726.3, 1072.5, 719.5, 1156.7 and 775.0 g穖^-2, respectively; and litter biomasses were 332.2, 294.0, 328.5, 271.4, 107.4, 97.2 and 155.7 g穖^-2, respectively. However, the community total biomasses had no significant difference in 7 kinds vegetation types. The value of them were 1353.9, 1240.8, 1405.3, 1501.0, 983.8, 1148.1 and 1075.3 g穖^-2, respectively. The belowground biomasses were larger than the aboveground and litter, and its distribution proportion ranged from 38.8% to 77.4%.The aboveground biomasses and litter biomasses significantly reduced with the increasing elevation (P<0.01) and aboveground biomasses significantly increased with the increasing precipitation (P<0.01), but reduced with the increasing annual mean temperature (P>0.05). The belowground biomasses responded to precipitation and temperature both were not significant. Therefore, precipitation is the major factor limiting the grassland ecological system biomass, and mainly restricted by the supply of water in the growing period. Temperature is not the main factor restricting the productivity of grassland ecological system.

Key words: Natural grassland, Biomass, Aboveground biomass, Belowground biomass, Environment factors

摘要： 草地生态系统是全球陆地生态系统的重要组成部分,在全球碳循环中扮演着重要角色。以陕西省天然草地为研究对象,基于57个调查样地的地上、地下和凋落物生物量资料,分析不同植被类型草地生物量的空间分布特征及其影响因素,并揭示其之间的相互关系,为我国草地生态系统碳汇研究提供基础数据。结果表明:7种草地类型(暖性草丛类、暖性灌草丛类、温性山地草甸类、温性草甸草原、温性草原、温性荒漠草原类和低地盐化草甸类)的各部分生物量存在显著差异(P<0.05),其地上生物量分别为:238.3,293.6,157.0,350.5,156.9,99.9和144.6 g·m^-2,地下生物量分别为:670.2,560.5,726.3,1072.5,719.5,1156.7和775.0 g·m^-2,凋落物生物量分别为:332.2,294.0,328.5,271.4,107.4,97.2和155.7 g·m^-2;但是其群落总生物量差异不显著,分别为:1353.9,1240.8,1405.3,1501.0,983.8,1148.1和1075.3 g·m^-2。地下生物量均大于地上生物量和凋落物生物量,其分配比例介于38.8%~77.4%之间;地上生物量和凋落物生物量随海拔高度增加而极显著减少(P<0.01);地上生物量随生长期降雨量增加而极显著增加(P<0.01),随年均温增加而减少(P>0.05);地下生物量对降雨和温度的响应均不显著。因此,降水是陕西省天然草地生态系统地上生物量最主要的限制因子,且主要受生长期水分供给的制约,温度尚不是主要限制因子。

关键词: 天然草地, 生物量, 地上生物量, 地下生物量, 环境因子