中温型草原和暖温型草原大针茅+羊草群落结构特征的比较

A Comparative Study on Structure Characteristics of Community of Stipa grandis+Leymus chinensis in Moderate-temperate Steppe and Warm-temperate Steppe

运用植被水平地带性原理在南北样带 ( NSCT)草原生物群区中温型草原和暖温型草原内的典型草原地带各选择一个研究站点 ,于 1 999～ 2 0 0 0年 5～ 9月份对大针茅 +羊草群落的数量结构、α多样性、生活型功能群组成、地上生产结构、C3 和 C4 植物组成及群落生长动态特征进行了比较研究。结果表明 :暖温型草原群落高度 ( h)、生态优势度 ( C)、C4 植物比例 ( % )和单位叶速率 ( ULR)较高 ,生长动态曲线呈双峰型且第 1峰大于第 2峰 ;中温型草原物种丰富度 ( R)、群落密度( d)、物种多样性 ( H ')、群落均匀度 ( E)、F/C值、叶面积指数 ( LAI)、叶面积持续时间 ( LAD)和干物质生产能力 ( P)较高 ,生长动态曲线呈单峰型 ,初期生长较快。虽然两站点年平均降水量相近 ,但温度、热量差异较大 ,年蒸发力不同 ,并影响到天然降水及土壤水分、养分供给的有效性 。

Applying the principle of horizontal zone of vegetation, a research station has been chosen respectively in the typical steppe zone lied the core part of Moderate-temperate Steppe and Warm-temperate Steppe in the Steppe Biome located in the North and South Transect of China (NSCT). A comparative study has been carried out concerning the numerical structure, α-diversity, composition of plant groups of life form, leaf layer structure above ground, proportion of C 3 and C 4, and grouth dynamic characteristics of the community of ASS. Stipa grandis + Leymus chinensis in the two stations from May to September during 1999~2000. The findings demonstrated that there are higher community height (h), ecological dominance (C), C 4 plant proportion (%) and unit leaf area rate (ULR) of the community in the Warm-temperate Steppe,and its growth dynamic curve shows the pattern of two peak value, and first peak value bigger than second one; while there are higher species richness (R), community density (d), species diversity (H'), community evenness (E), value of F/C, leaf area index (LAI), leaf area duration (LAD) and productivity of dry matter (P) of the community in the Moderate-temperate Steppe, and its growth dynamic curve shows the pattern of single peak value, increasing faster at initial stage of the growth seasons. Although the average precipitation is very close in the two stations, the bigger difference in temperature and thermal condition make their evaporation come into being great disparity, affecting the effective supply from natural precipitation and water and nutrient of soil, seemed to be the chief cause result in the differences in the structure and growth of the communities. The findings can provide the basis for prediction of influences on the steppe ecosystem by global change in future.