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退耕地人工植物群落根系生态位及其分布特征 预览 被引量:29

Discussion of root ecological niche and root distribution characteristics of artificial phyto-communities in rehabilitated fields
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摘要 根系生态位研究是全面掌握植物群落特性、种间搭配以及生态功能的重要科学问题,其测度方式、分布特征、影响因素等方面内容,对于合理指导退耕还林还草工程十分必要.将植物群落根系视为'标准地',分布于每个土体层次的每个径级根系视为'植物种',根量、根长、根数作为'植物种'的观测变量,仿照群落生态学方法,提出了一种综合计算根系生态位指数的方法.即将整个研究区域作为一个系统,将这一系统中所有植物群落,统一选用指标最大值,在纵向(即相对于指标维的不同指标)用上限效果测度公式统一进行归一化处理,然后在横向(土层、径级间,简称层径级)进行合并运算,得出层径级根系参数,这一参数定义为层径级根系生态位指数;而将某一群落各层径级生态位指数之和,定义为植物群落根系生态位指数,从而使区域内所有植物群落间具有可比性.使用这一方法,对国家退耕还林还草科技试验县--青海省大通县退耕地人工植物群落根系进行了系统研究.研究结果表明,根系生态位垂直空间分布大多数为典型的表层聚积型,表土层0~20cm根系生态位指数明显高于其它层次.植物群落根系比单一种群或纯林根系具有更高的生态位指数.根系生态位径级分布包括J型、反J型、S型和U型.J型多为粗根-深根型植物群落根系,反J型为细根-浅根型植物群落根系,S型和U型为上述2种类型之间的过渡型.根系生态位指数与植物群落地上部分鲜重生物量、根系丰富度呈显著正相关.退耕地植物群落根系的生态位指数较为接近天然植被,明显高于农作物根系.青海云杉+中国沙棘、中国沙棘、青海云杉等3种植物配置模式更有利于退耕地植物根系生态位的恢复.实施退耕还林还草工程是有效增加根系生态位、提高根系多方面功能的重要途径. In the implementation phase of the Conversion of Cropland to Forest and Grassland (CCFG) project in China, it is important, from a scientific point of view, to recognize the characteristics of phyto-communities, species compatibility and their ecological function. We must also acknowledge the ecological niche that roots occupy, their abundance and distribution as well as the factors which affect them. Following the methodology of community ecology, we measure the total root mass of the phyto-community as a cubic volume. Root biomass, length and number of roots in every diameter class, for each soil layer and for each different plant species are regarded as observation variables.In first instance therefore, we propose a new method to calculates the ecological niche index of roots (RENI), embracing the entire phyto-community of plantations. In the methodology all of the study area will be treated as one system, which requires that all data be standardized to the maximum of three root indexes respectively and summed by root diameter groups in each soil layer in order to obtain the RENI of each root layer. We define the sum of all the RENIs of each soil layer as the RENI of the phyto-community in order to be able to compare different plant communities in the area easily and in a scientific manner. In the new method we propose in our paper, we deal with the roots of the phyto-communities in Datong county, Qinghai province, one of the counties selected for the national CCFG experiment. The results show that most of the vertical distribution of plant roots belong to the type where the roots are concentrated in the top soil layer (0~20 cm), far more than in the lower soil layers.The RENI of phyto-communities is higher than that of pure stands or a monoculture.The distribution of RENI by root diameter can be divided into four types: the J type, the inverse J type, the S type and the U type. For plants of the J type, most roots are thick, deeply imbedded in the soil and act as soil stabilizers.Plants of the inverse J typ
作者 胡建忠 郑佳丽 沈晶玉 HU Jian-Zhong, ZHENG Jia-Li, SHEN Jing-Yu (College of Soil and Water Conservation,Beijing Forestry University; Key Lab. of Soil and Water Conservation and Desertification Combating of the Ministry of Education,Beijing 100083,China).
出处 《生态学报》 CAS CSCD 北大核心 2005年第3期 481-490,共10页 Acta Ecologica Sinica
基金 国家重点基础研究发展计划(973计划),国家科技攻关项目
关键词 退耕地 人工植物群落 根系生态位 分布特征 RENI distribution root layer phyto-community rehabilitation field
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