Aboveground biomass of main shrubs in dry valley of Minjiang River
LIU GuoHua1, MA KeMing1, FU BoJie1, GUAN WenBin2, KANG YongXiang3, ZHOU JianYun3,LIU ShiLiangnmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; 2. Water and Soil Conservation Laboratory of National Forestry Bureau, Beijing Forestry University, Beijing 100083, China; 3. Northwestern Science and Technology University of Agriculture and Forestry, Yangling 712100, Shaanxi Province, China).
Biomass is one of major parameters of ecosystem function. Compared with that for forest ecosystem, little attention has been paid for biomass for shrubs. Shrub, as a main vegetation type, is widely distributed worldwide. In China, due to climate and human activities, there are large areas of shrub ecosystems that play an important role for regional environment protection. Therefore, it is necessary to study shrub biomass. Shrub is a dominant vegetation type in the dry valley of Minjiang River. It plays vital role for water and soil conservation in this region. In this paper we report shrub aboveground biomass in this area based on field measurement. The results are summarized as follow. (1) Aboveground biomass was very different among 9 shrub types, ranging from 14702 kg·hm-2 (Onosma shrub) to 115542 kg·hm-2 (Sageretia pycnophylla shrub). The reasons for such a large difference may include dominant species, species composition, altitude, slope, soil moisture, etc. (2) Aboveground biomass increased with an increase of altitude; a strong correlation between the aboveground biomass and altitude was especially found in the core section of the valley.(3) Increased soil moisture along altitudinal gradient might lead to an increase in aboveground biomass in the edge region (sample belt1). However, this correlation was weak for the core section (sample belt2), probably due to very low soil moisture in the core region. This suggests that soil moisture is the main limited factor for shrub growth in the valley. Such a pattern of shrub biomass and soil moisture along the altitudinal gradient is likely related with the foehn. In the dry valley, the lower altitude is, the stronger effect of foehn is. Thus, the growth of shrub is always limited at the condition of lower soil moisture. With a rise of altitude, the effect of foehn is weakened, and therefore soil moisture is increased. In the core region of dry valley, the stronger effect of foehn causes a very low soil moisture. This emphasizes that soil moisture is a major limited factor for shrub growth in this area. Furthermore, the frequency of human activity is higher at piedmont. This is also one reason why aboveground biomass is smaller in the lower altitude. The results from this study should provide scientific bases for protection of shrub vegetation and restoration of degraded ecosystems in the dry valley of Minjiang River.
【Fund】： 国家重点基础研究发展规划资助项目(G2000046807;2002CB412500-03);; 国家自然科学基金资助项目(40171085);; 国家"十五"攻关课题资助项目(2001BA606A-01)~~
【CateGory Index】： Q948.12
【CateGory Index】： Q948.12