Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China.
Plant Biol (Stuttg). 2011 Jan;13(1):85-92. doi: 10.1111/j.1438-8677.2010.00321.x.
It is unclear whether the shift in leaf traits between species of high- and low-rainfall sites is caused by low rainfall or by species replacement, because leaf traits vary substantially among species and sites. Our objective was to test if the within-species relationship between specific leaf area (SLA) and leaf N concentration (N(mass) ) shifts across a rainfall gradient in the semi-arid sandy lands of northern China. Data for SLA and N(mass) of dominant species and related canopy and soil variables were collected from 33 plots along a rainfall transect (270-390 mm) having similar temperatures in the Mu Us, Inner Mongolia. We further investigated the generality of Mu Us data using 12 additional plots in the southeastern Qaidam Basin, Qinghai. Artemisia ordosica is a widespread species in both regions. Across and within species, the positive SLA-N(mass) relationship shifted between two plant groups in the lowest rainfall plots (270 mm) and other higher rainfall plots (320-390 mm), which was confirmed by additional data from Qinghai. For A. ordosica populations, leaf area index (LAI) decreased and N(mass) increased with decreasing rainfall, while the foliage N pool and SLA varied little. Rainfall was the limiting factor that determined variations in N(mass) and LAI. Accordingly, N(mass) /SLA ratios continually increased with decreasing LAI along the rainfall gradient (r = -0.76, P < 0.001). Results indicate a low rainfall-induced shift in the SLA-N(mass) relationship associated with changes in LAI and foliage N pool, suggesting a link between leaf characteristics and ecosystem function.
目前尚不清楚高降雨和低降雨地点物种之间的叶片特征变化是由低降雨量引起的，还是由物种更替引起的，因为叶片特征在物种和地点之间存在很大差异。我们的目标是检验在中国北方半干旱沙质土地的降雨梯度范围内，物种内比叶面积（SLA）与叶片氮浓度（N(mass)）之间的关系是否会发生变化。在内蒙古毛乌素，从降雨量为 270-390mm 的降雨梯度上的 33 个样方中收集了主要物种的 SLA 和 N(mass)数据以及相关的冠层和土壤变量的数据，这些样方具有相似的温度。我们还使用青海柴达木盆地东南部的 12 个附加样方进一步研究了毛乌素数据的普遍性。在这两个地区，Artemisia ordosica 都是分布广泛的物种。在跨物种和种内，最低降雨量（270mm）的两个植物群之间的正 SLA-N(mass)关系发生了转变，其他较高降雨量（320-390mm）的植物群也发生了转变，青海的数据进一步证实了这一点。对于 A. ordosica 种群，叶面积指数（LAI）随降雨量的减少而降低，N(mass)随降雨量的减少而增加，而叶氮库和 SLA 变化不大。降雨量是决定 N(mass)和 LAI 变化的限制因素。因此，随着降雨梯度的降低，N(mass)/SLA 比值不断增加（r = -0.76，P < 0.001）。结果表明，低降雨量引起的 SLA-N(mass)关系的变化与 LAI 和叶氮库的变化有关，这表明叶片特征与生态系统功能之间存在联系。
