拉萨-林芝植被样带不同群落类型的细根生物量

细根通常是指植被地下根系中直径小于2 nun的根,其生产和周转直接影响着整个生态系统的碳平衡和养分循环.在森林生态系统中约3%～84%(大部分为10%-60%)的净初级生产力被用于细根的生产(张小全等,2001);而细根的周转则是森林土壤C累积的最大输入量,如果忽略细根的生产、死亡和分解,土壤有机物质和养分元素的周转将被低估20%-80%(Vogt et al.,1986;1996).

Biomass of Fine Root in Different Community Type on the Tibetan Vegetation Transect

Fine root biomass was measured by soil core sampler in four community type on Tibetan Plateau, of which include two coppice of Betida platyphylla and Quercus aquifolioides , one shrub of Salix oritrepha, and one coniferous woodland of Pinus densata. The fine root density were Betida platyphylla of (785.9±290.4) g·m~(-2), Quercus aquifolioides of (801.0±279.5) g·m~(-2) , Salix oritrepha of (376.0±146.0) g·m~(-2) and Pinus densata of (431.2 ±171.1) g·m~(-2) . Result showed that the fine root density of two coppices was significantly higher than that of shrub and coniferous woodland. Dead fine root was 16.2% of the total fine root in Betula platyphylla, and the percentage were about 25% in other three type of forest. Distribution of fine root had the same pattern that high density of fine root appeared at 0～10 cm soil depth.