草原植物根系起始吸水层深度测定方法及其在不同群落状态下的表现  

Determination of the initial depth of water uptake by roots of steppe plants in restored and overgrazed communities,Inner Mongolia,China

作　　者：郭宇然[1] 王炜[1] 梁存柱[1] 王立新[2] 刘华民[1] 

机构地区：[1]内蒙古大学生命科学学院,呼和浩特010021 [2]内蒙古大学环境与资源学院,呼和浩特010021

出　　处：《生态学报》2012年第6期1880-1887,共8页Acta Ecologica Sinica

基　　金：国家自然科学基金项目(31060076;40861002;30330120);国家科技支撑计划项目(2011BAC02B03;2008BAD95B03)

摘　　要：通过比较实验导出用于研究草原群落中不同植物种群起始吸水层研究方法,暂称之为"土体挖空法"。该方法是将土壤剖面的下部挖空,保留上面0—5、0—10、0—15 cm的土层和上面的全部植物,当从地表浇的水在被挖空部分的向下表面开始渗出时测定哪些植物种群吸收了水分。实验中用于检验植物是否吸水的方法是用水势仪测定法。在内蒙古锡林郭勒盟白音锡勒牧场中国科学院草原生态系统定位研究站的实验样地上,通过对处于不同退化恢复演替阶段的草原群落中主要植物种群的研究得出以下结论:1)同一群落中不同植物种间根系起始吸水层存在差异,在恢复群落中存在根系起始吸水位置的生态位分离和重叠现象,其中黄囊苔草(Carex korshinskyi)、冷蒿(Artemisia frigida)、糙隐子草(Cleistogenes squarrosa)的起始吸水层位置表明它们在对土壤中水资源利用空间维上存在空间生态位重叠现象;羊草(Leymus chinensis)、大针茅(Stipa grandis)、米氏冰草(Agropyron michnoi)之间也存在类似的生态位重叠;两组植物种群间存在对土壤中水资源利用空间维上的空间生态位分离现象。2)无论是否退化的草原群落,其中黄囊苔草、冷蒿、糙隐子草的根系起始吸水层深度保持不变;在严重退化的群落中羊草、大针茅、米氏冰草同种个体的起始吸水层则变浅,即呈浅层化分布现象。退化群落中,植物体小型化和根系浅层化的同时植物根系对水分吸收的起始位置总体呈浅层化。3)典型草原群落中各植物种群间存在较大幅度的生态位重叠和一定的生态位分离,其中生态位分离的幅度较小,重叠的程度较大。We studied water uptake by plant roots in two typical steppe communities, at the Inner Mongolia Grassland Ecosystem Research Station of the Chinese Academy of Sciences, Xilin Gol League, Inner Mongolia, China. Water uptake by roots forms the base of the SoilPlant Atmosphere Continuum. Previously, a model of root water uptake has been used, based on root distribution, but there has been no effective way to research water uptake of steppe plants directly. We used a new method to determine where the pant roots begin the uptake of water. First, we excavated to the subsoil and measured soil water seepage in the selected plots. By watering the plants and then measuring leaf water potential using a water potential system, we were able to use changes in water potential to indicate water uptake. The initial depth of water uptakeby roots could thus be determined indirectly. We contrasted two different successional communities, a recovery plot enclosed since 1983, and an open, grazed, degraded plot. Second, we measured uptake by some major plants in different successional communities. We found that the initial depth of water uptake by roots could be measured using the soil excavation method described. In the degraded community, six species showed initial root water uptake at 0 --5 cm beneath the surface, Agropyron michnoi, Artemisia frigida, Carex korshinskyi, Cleistogenes squarrosa, Leymus chinensis and Stipa grandis. In the restored community, different species exhibited deeper initial uptake of water. The initial depth of water uptake by roots of Carex korshinskyi, Cleistogenes squarrosa and Artemisia friglda was 0 -5 cm below the surface. Here a spatial niche overlap exists in the exploitation of water. However, initial uptake depth of Leymus chinensis, Stipa grandis and Agropyron michnoi was 5 -10 cm, these species also share a similar niche. Obviously, the former species uptake water more shallowly than the latter, providing evidence for some spatial separation of water utilization niches. In a different restored comm

关 键 词：退化演替 生态位 植物水势 根系 典型草原 吸水 

分 类 号：S812[农业科学—草业科学]