Species-dependent responses of juniper and spruce to increasing CO2 concentration and to climate in semi-arid and arid areas of northwestern China
Species-dependent responses of juniper and spruce to increasing CO2 concentration and to climate in semi-arid and arid areas of northwestern China
复制标题
中国西北半干旱和干旱地区杜松和云杉对二氧化碳浓度增加和气候的物种依赖性响应
DOI：
10.1007/s11258-006-9258-5
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发表时间：
2007-12-01
期刊：
影响因子：
1.7
通讯作者：
Ren, Jiawen
中科院分区：
文献类型：
--
作者：
Liu, Xiaohong;Shao, Xuemei;Ren, Jiawen
祁连圆柏和青海云杉（PiceacrassifoliaKom.）代表了不同的树木功能类型，广泛分布于我国西北地区。前者耐旱，后者喜湿，耐阴。我们比较了它们的内在水分利用效率（iWUE，从碳同位素歧视，δ 13 C，在他们的木材）作为大气CO2浓度，[CO2]和气候的函数。云杉的δ 13 C在半干旱地区始终高于杜松，但在干旱地区低于杜松。这种差异是稳定的，随着时间的推移，表现出很强的交叉相关性物种之间，虽然一些微妙的高频（2或3年）的变化存在于两个物种，这表明区域气候可能控制碳同位素歧视。$${C_{\rm i}/C_{\rm a}}$$比值（叶细胞间和大气中的[CO2]值）的杜松稳步上升，随着时间的推移，而云杉则呈长期下降趋势。在150年的研究期间，所有地点的IWUE都有所增加，主要是由于[CO2]增加。iWUE和[CO2]之间的关系表明，云杉比杜松更敏感，增加[CO2]，表明物种特异性的适应长期的环境变化。稳定碳辨别力（Δ）的高频变化与气候的相关性表明，两个物种对气候的响应具有相似的地点内响应，但响应强度不同。总体而言，温度和湿度的复杂的相互作用，稳定的碳歧视在当前的生长季节的两个物种的环境决定。调节气体交换和减少蒸腾作用可能会直接影响水分和能量收支，因此，在未来的全球植物生理生态学研究中，应考虑树木对CO2浓度升高的物种依赖性反应。
Qilian juniper (Sabina przewalskii Kom.) and Qinghai spruce (Picea crassifolia Kom.) represent different tree functional types, which can be found extensively in northwestern China. The former is drought-tolerant, whereas the latter is hygrophilous and shade-tolerant. We compared their intrinsic water-use efficiency (iWUE, inferred from carbon isotopic discrimination, δ13C, in their wood) as a function of atmospheric CO2 concentration, [CO2], and climate. δ13C of spruce was consistently about $${1.23\permille}$$ higher than that of juniper in semi-arid areas but was lower in arid areas. This difference was stable over time and demonstrated strong cross-correlations between species, although some subtle high-frequency (2 or 3 years) variations existed in both species, suggesting that regional climate may control carbon isotope discrimination. The $${{C_{\rm i}/C_{\rm a}}}$$ ratio (the [CO2] values in leaf intercellular and the atmosphere, respectively) of the juniper increased steadily over time, whereas that of the spruce showed a long-term downward trend. IWUE increased at all sites over the 150-year study period, mainly caused by increasing [CO2]. The relationship between iWUE and [CO2] reveals that the spruce was more sensitive than the juniper to increasing [CO2], suggesting a species-specific adaptation to long-term environmental changes. Correlations between the high-frequency variations in stable carbon discrimination (Δ) and climate indicate similar intra-site responses to climate in both species, but different response strengths. Overall, complex interactions of temperature and moisture on stable carbon discrimination during current growth seasons of both species were environmental-determined. Regulation of gas exchange and reduced transpiration may influence water and energy budgets directly; therefore species-dependent responses of trees to elevated CO2 should be considered in future research on global plant physiological ecology.