不同生境下荒漠植物红砂-珍珠猪毛菜混生根系的垂直分布规律  

Vertical distribution pattern of mixed root systems of desert plants Reaumuria soongarica and Salsola passerina under different environmental gradients

作　　者：单立山[1] 苏铭 张正中[1] 王洋 王珊 李毅[1] SHAN Li-Shan;SU Ming;ZHANG Zheng-Zhong;WANG Yang;WANG Shan;and LI Yi(College of Forestry Sciences, Gansu Agricultural University, Lanzhou 730070, Chin)

机构地区：[1]甘肃农业大学林学院,兰州730070

出　　处：《植物生态学报》2018年第4期475-486,共12页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(31560135);甘肃省自然科学基金(1606BJZA005);甘肃省科技支撑项目(1604FKCA088);甘肃省重点研发计划项目(17YF1WA161)~~

摘　　要：植物种间相互作用及其对环境胁迫的响应一直是物种共存和生物多样性维持研究的一个热点,从地下根系入手来探讨混生群落植物种间关系及其对环境胁迫响应的研究少见报道。该文以荒漠草原区(灵武)、典型荒漠区(张掖)和极端荒漠区(酒泉)3个不同生境条件下单生与混生红砂(Reaumuria soongarica)和珍珠猪毛菜(Salsola passerina)为实验材料,采用分层取样法对其垂直根系参数进行测定和分析,探讨了两种植物根系分布对混生及荒漠环境梯度的响应。结果表明:同一生境条件下,混生红砂和珍珠猪毛菜比根长和比表面积均高于单生,说明红砂、珍珠猪毛菜混生后其根系相互作用关系表现为互惠,促进了植株对土壤养分和水分的吸收。不同生境条件下,同一生长方式的红砂根系分布深度均大于珍珠猪毛菜,且根系消弱系数也普遍高于珍珠猪毛菜,说明二者在不同生境条件下占据不同生态位,红砂表现为深根性,根系位于土壤深层,珍珠猪毛菜表现为浅根性,根系分布于土壤浅层。随着荒漠环境胁迫增强,单生和混生红砂与珍珠猪毛菜的比根长和比表面积均呈现出极端荒漠区>典型荒漠区>草原荒漠区的规律,且生境越干旱,混生群落根系分离越明显;单生与混生红砂根系消弱系数也逐渐增大,在极端干旱区达到最大值,珍珠猪毛菜变化不大,表明红砂-珍珠猪毛菜混生群落根系生态位分离随荒漠环境胁迫增强而加大,验证了环境胁迫梯度假说。可见"地上聚生,地下分离"的混生方式可能是红砂-珍珠猪毛菜混生群落适应干旱胁迫环境的生长策略。Aims How plant species interaction changes along environmental gradients has remained a hot issue in studies of species coexistence and biodiversity maintenance. This study was conducted to determine the responses of root systems to drought stress in desert Reaumuria soongarica-Salsola passerina communities, in order to better understand the interspecific relationships of plant communities in response to environmental stresses. Methods Monocultural and mixed R. soongarica and S. passerina communities were selected in Lingwu, Zhangye and Jiuquan, representing a drought stress gradient varying from desert steppe habitat to extreme desert habitat. Measurements were made on the vertical structures of root traits including specific root length（SRL） and specific root surface area（SRA）. Root samples were collected by trench method by layers. Important findings Both SRL and SRA had greater values in mixed R. soongarica-S. passerina communities than in monocultural communities of either species within given habitat, suggesting a mutually beneficial relationship between the two species and the enhanced ability of roots to absorb soil nutrients and water when in mixture. Reaumuria soongarica had deeper roots and a greater root extinction coefficient in vertical distribution than S. passerina in either monocultural or mixed communities, indicating the belowground niche segregation between the two species. We also found that greater the environmental stress, the higher values of SRL and SRA in both R. soongarica and S. passerina. The root extinction coefficient was about the same between the monocultural and mixed communities for R. soongarica, but changed a little for S. passerina. With increasing drought stress, the belowground niche segregation became more apparent, conforming to the stress gradient hypothesis. The observed patterns of aggregation aboveground and segregation belowground between R. soongarica and S. passerina in the mixed communities might be an adaptive strategy to drought environment of these two

关 键 词：根系垂直分布 根系消弱系数 种间关系 环境胁迫梯度假说 红砂 珍珠猪毛菜 

分 类 号：Q948[生物学—植物学]