细根（直径≤2mm）是植物吸收水分和养分的重要器官,细根通过呼吸作用和周转过程向土壤输送有机质（Jackson et al.,1997;王政权等,2008）。细根生物量虽然仅占植物体总生物量的5%左右,但由于细根生长和周转迅速,其生长量可占森林初级...细根（直径≤2mm）是植物吸收水分和养分的重要器官,细根通过呼吸作用和周转过程向土壤输送有机质（Jackson et al.,1997;王政权等,2008）。细根生物量虽然仅占植物体总生物量的5%左右,但由于细根生长和周转迅速,其生长量可占森林初级生产力的50%～75%（Nadelhoffer et al.,1992）。展开更多
At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanis...At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen(N), magnesium(Mg), potassium(K), and foliar phosphorus(P) decrease significantly with elevation. Foliar manganese(Mn) concentrations, bycontrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions.展开更多
文摘细根（直径≤2mm）是植物吸收水分和养分的重要器官,细根通过呼吸作用和周转过程向土壤输送有机质（Jackson et al.,1997;王政权等,2008）。细根生物量虽然仅占植物体总生物量的5%左右,但由于细根生长和周转迅速,其生长量可占森林初级生产力的50%～75%（Nadelhoffer et al.,1992）。
文摘At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen(N), magnesium(Mg), potassium(K), and foliar phosphorus(P) decrease significantly with elevation. Foliar manganese(Mn) concentrations, bycontrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions.
