桂西北喀斯特坡地典型生境不同植物叶片的碳同位素差异

Differences in foliar carbon isotope ratio of dominant plant species in representative habitats on karst hill slopes of northwest Guangxi,China

通过测定7种典型植物的叶片δ13C值,比较了桂西北喀斯特坡地连片裸露石丛及其临近浅薄土层处植物叶片δ13C值及其季节性差异。结果表明:旱季(2008年11月、2009年3月)植物叶片δ13C值显著高于雨季(2009年7月)(P<0.05);旱季和雨季菜豆树、铁线莲、黄荆的δ13C值无显著差异(P>0.05),而盐肤木、红背山麻杆、蕨、肾蕨旱季显著高于雨季(P<0.05);季节性降雨差异对乔木类菜豆树、藤本类的铁线莲以及根系较深灌木叶片δ13C值的影响较小,而对浅根系草本植物、浅根灌木影响较大;旱季和雨季2种生境下菜豆树叶片δ13C值差异均不大,旱季和雨季连片裸岩生境的红背山麻杆和黄荆叶片δ13C值与临近浅薄土层生境值的差异虽不显著(P>0.05),但差异大于菜豆树,说明生境条件的差异对这2种灌木叶片δ13C值的影响较大。

Based on the measurements of the foliar δ13C values of seven dominant plant species on the continuous rock outcrops and nearby soils on karst hill slopes of northwest Guangxi,China,this paper analyzed the differences in the foliar carbon isotope ratio of the plants in different habitats and different seasons. The foliar δ13C values of test plants were significantly higher in dry season than in wet season （P0.05）. Radermachera sinica,Vitex negundo,and Clematis kweichowensis had no significant differences in their foliar δ13C values in wet season and dry season （P0.05）,but Rhus chinensis,Alchornea trewioides,Nephrolepis auriculata,and Pteridium aquilinum had significantly higher foliar δ13C values in dry season than in wet season （P0.05）,which suggested that the seasonal differences in rainfall had less effects on the foliar δ13C values of R. sinica,V. negundo,and deep-rooted shrub,but had great effects on those of shallow-rooted grass and shrub. No significant differences were observed in the foliar δ13C values of R. sinica,A. trewioides,and V. negundo on the continuous rock outcrops and nearby soils both in dry and in wet seasons （P0.05）,but the foliar δ13C values of the shrubs differed greatly in the two habitats both in dry and in wet seasons,suggesting that habitat condition had great effects on the foliar δ13C values of shrub than of deep-rooted tree.