不同组成群落3种共有植物光合生理特征研究

为研究物种在不同群落中光合生理特征的变化,以亚高寒草甸围封恢复地为研究对象,对样地内3个不同组成群落进行样方调查,测定了物种高度及各群落垂直方向上光照强度以及群落中3个共有种披碱草(Elymus dahuricus)、刺儿菜(Cirsium setosum)和紫花苜蓿(Medicago sativa)的净光合速率(Aarea)、叶片氮含量(Nmass)、比叶重(LMA)及光合氮利用效率(PNUE)。结果表明:(1)3个样地的群落组成有明显的差异,豆科植物的增多可以一定程度上改善群落氮养分状况,但植物叶片Nmass还受到群落优势种竞争的影响。(2)同一物种在不同群落的高度不同,不同群落垂直方向上光照强度也不相同,导致同一物种在不同群落中能够获得的光照强度有一定差异。(3)在养分、光照强度有差异的情况下,不同植物的Aarea、LMA及PNUE在不同群落中的变化趋势不尽相同,而Narea与Aarea的关系在总体上、群落间及物种间变化不大,基本上显示了较强的正相关关系。由此可见,群落组成、结构引起的光照及氮素差异是导致同一物种光合生理特征在不同群落中变化的重要因素,但不同物种光合生理特征对光照及氮素变化的响应不同。

Photosynthetic and Physiological Characteristics of Three Common Species in Different Communities

The article focuses on the enclosed grassland in sub-alpine meadow.We examined the composition of three different communities by the methods of quadrat survey,measured area-based leaf CO₂ assimilation rate(A_area),foliar nitrogen content(N_mass),leaf mass per area(LMA) and photosynthetic nitrogen-use efficiency(PNUE) of three common species Elymus dahuricus,Cirsium setosum and Medicago sativa to study the variation of plant photosynthetic and physiological characteristics in different communities.The results show that:(1)there is obvious composition difference between three sample areas,community composition,particularly leguminous plants can improve nutrient status.However,plant foliar nitrogen content is influenced by dominant interspecific competition;(2)the same species has different height in different communities and the different communities have different vertical light intensity as well,which lead to significant different of light intensity that same species can obtain in different communities;structure including plant height alter light intensity that plants enable harvested significantly;(3)the illuminance and nutrient are variant between communities,though the variation tendencies of A_area,LMA and PNUE are not same to different plants.However,the strong relationship between N_area and A_area is little changed in general,between communities and among species,basically shows a significant positive correlation.Thus it can be seen that the difference in nitrogen and light intensity caused by community composition and structure is an important factor which lead to different photosynthetic physiological characteristics with same species,while different species have different photosynthetic adaptive mechanism to changing environment.