放牧强度对半干旱草地优势植物赖草功能性状的影响

放牧是草原生态系统中草地利用的主要方式,研究草地植物功能性状对长期放牧干扰的响应策略具有重要意义。本文以晋北农牧交错带半干旱草地为例,研究优势植物赖草(Leymus secalinus)功能性状在不同放牧强度下的变化,结果表明：放牧显著降低了赖草株高等形态结构性状以及茎叶比等生产力性状(P<0.05),中度放牧与不放牧的差异最小;整株干重(地上部分)的变异系数(52.92%)和可塑性指数(93.17%)最大;生产力性状、光合生理性状和化学计量3类性状内部指标之间的相关性均为极显著正相关(P<0.01);茎氮磷比等性状是赖草响应放牧干扰的主要功能性状。本研究表明,中度放牧下,赖草具有补偿性生长的能力,矮化型变特征和非对称性响应机制是赖草在放牧干扰下的主要适应方式。

Effects of Grazing Intensities on Functional Traits of the Dominant Plant Leymus secalinus in Semi-arid Grassland

Grazing is the main way of grassland utilization in grassland ecosystems. It is of great significance to study the response strategies of functional traits of grassland plants to long-term grazing disturbance. In this paper,we studied the changes of functional traits of the dominant plant Leymus secalinus under different grazing intensities,with the semi-arid grassland of farming-pastoral transition zone in northern Shanxi Province as an example. The results showed as follows:grazing significantly lowered the morphological structure traits such as plant height and the productivity traits such as the ratio of stem to leaf of L. secalinus (P<0.05),with the least difference between moderate grazing and no grazing;the coefficient of variation (52.92%) and plasticity index (93.17%) of whole plant dry weight (aboveground) were the highest;the correlation among the internal indexes of three functional traits such as productivity traits,photosynthetic physiological traits and stoichiometry was very significant positive correlation (P<0.01);stem N/P ratio,stem length,ratio of stem to leaf,leaf N/P ratio,plant height,leaf length,leaf area and whole plant dry weight (aboveground) were the main functional traits of L. secalinus in response to grazing disturbance. This study showed that under moderate grazing,L. secalinus had the ability of compensatory growth,and dwarf morphological characteristics and asymmetric response mechanism were the main adaptation modes of L. secalinus under grazing disturbance.