论文部分内容阅读
为了认识树种叶片水分利用效率的种内和种间差异及随水分生境条件和季节的变化特征,2010年6—9月份,在宁夏六盘山香水河小流域(半湿润区)和叠叠沟小流域(半干旱区),测定了两种不同水分生境内主要树种的叶片稳定碳同位素组成(δ13C)。结果表明:同一树种叶片δ13C值存在着明显的冠层部位差异,但各树种表现各异,其中华北落叶松(Larix prin-cipris-rupprechtii)、白桦(Betula platyphylla)和油松(Pinus tablaeformis)表现为上部>中部>下部,而华山松(Pinus arman-dii)和辽东栎(Quercus liaotungensis)为下部>上部>中部。各树种叶片的δ13 C值表现出明显的季节变化特征,但其变化随水分生境条件而异。在半湿润区,各树种的δ13 C值在生长季初期较高,但随生长季的持续而降低;在半干旱区,各树种的δ13C值呈现出“高—低—高”的变化态势。在两种不同水分生境下,华北落叶松和沙棘(Hippophae rhamnoildes)叶片的δ13 C值存在着明显的种内个体差异:旱季,同一树种在半干旱区树木叶片的δ13C要大于半湿润区;但雨季两地树木叶片的δ13C差异不大,说明这种季节差异受当地降雨量的季节分配格局影响较大。
In order to understand the intraspecific and interspecific differences in water use efficiency (WUE) of tree species and their changing characteristics with the changing of water habitat and season, from June to September in 2010, (Semi-arid zone), the stable carbon isotope composition (δ13C) of the major tree species in two different aquatic habitats was determined. The results showed that the δ13C value of the same tree species showed obvious difference in canopy position, but the species of the tree species varied significantly. Among them, Larix principris-rupprechtii, Betula platyphylla and Pinus tabulaeformis Upper> middle> lower, while Pinus arman-dii and Quercus liaotungensis are lower> upper> middle. The δ13C value of each tree species showed obvious seasonal variation, but its variation varied with the water habitat. In the semi-humid zone, the δ13C values of all species were higher in the early growing season but lower with the growing season, while in the semi-arid region, the δ13C values of all species showed a “high-low-high” change situation. The δ13C values of leaves of Larix principis-rupprechtii and Hippophae rhamnoildes showed obvious intra-species and individual differences in two different habitats. In the dry season, δ13C of the same tree species in the semi-arid area was greater than that in the semi-humid area. However, The difference of δ13C in tree leaves between two rainy seasons was not significant, which indicated that the seasonal difference was greatly affected by the seasonal distribution pattern of local rainfall.