去叶对青杨雌雄植株生长和非结构性碳水化合物的影响

近年来,森林食叶害虫在全世界呈爆发趋势。树木的非结构性碳水化合物(NSC)如何响应叶片损失对其生长和生存至关重要。雌雄异株植物在维持森林生态系统稳定性方面扮演着重要角色。然而,目前对该类植物性别之间如何响应去叶的研究还比较少。本文以我国重要的经济和生态恢复树种青杨(Populus cathayana)为研究材料,比较了雌雄青杨幼苗的生长、NSC含量和储量对去叶(0,50%和100%叶片去除)的响应差异。结果表明:随去叶强度的增加,植物的生物量和植株NSC呈降低趋势,且根系(尤其是粗根)的生物量和NSC比地上部分受去叶的影响更大;雌株叶、粗根、细根和植株NSC储量总是高于雄株;随去叶强度增加,雄株的生物量积累和NSC含量和储量降低得比雌株更多。这些结果表明,青杨雌雄植株生长和NSC对不同去叶强度的响应存在性别差异,且去叶对青杨雄株的影响更大。这暗示了雌性青杨对去叶的耐性比雄性强。这些结果有助于理解雌雄异株植株性别水平上的碳平衡机理,也可为杨树人工林的选育提供支撑。

Effects of defoliation on growth and non-structural carbohydrates in female and male Populus cathayana

Outbreaks of forest defoliating insects are becoming more frequent and severe across the globe. The responses of non-structural carbohydrates( NSC) in trees to leaf loss are crucial for their growth and survival. Dioecious plant species play a significant role in maintaining forest stability,yet few studies have investigated sex-related effects of defoliation on growth and NSC. In this study,we investigated sex-related responses of growth and NSC to varying levels of defoliation( 0,50%,and 100% leaf removal) in Populus cathayana,an ecologically and economically important woody species widely distributed in China. We measured plant biomass,NSC concentrations and pools in different organs. Biomass and NSC concentrations and pools decreased with increasing defoliation intensity,with such trend being more pronounced in roots( especially coarse roots) than in shoot. Female NSC pools in leaves,coarse roots,fine roots and whole-plant were always greater than male pools. Biomass and NSC concentrations and pools in males decreased more than for females with increasing defoliation intensity. Male P. cathayana suffered stronger negative effects on growth and NSC than the females under defoliation,which suggested that females had a higher tolerance to defoliation than males. Our results contribute to understanding the mechanisms of tree carbon balance across sexes,with implications on silviculture of poplar plantations.