摘要
灌丛"肥岛"是全球干旱生态系统中的普遍现象,其发生和发展对干旱灌木、草原生态系统的结构和功能都具有重要影响,但其物种效应容易得到忽视。对准噶尔盆地南缘柽柳(Tamarix spp.)和梭梭(Haloxylon ammodendron)这两种不同地表形态灌木的冠下、冠缘和灌丛间地3种生境的土壤进行了采样、分析,结果表明:(1)柽柳和梭梭都存在"肥岛"现象,主要表现在土壤表层,其土壤性状与"岛"外土壤的差异随土壤深度增加而减弱;(2)生物性限制土壤养分由"岛"内向外梯度递减,而非生物性限制土壤要素可能高于、也可能低于"岛"外土壤,或者两者无显著差异;(3)从"肥岛"的空间尺度来看,柽柳"肥岛"的水平范围可能超出了本身冠幅覆盖区,而梭梭"肥岛"要小于本身冠幅覆盖区,其深度亦小于柽柳"肥岛";(4)相对于不同土壤要素而言,即使是同一物种,其"肥岛"也具有不同的空间范围。总的来看,研究区灌丛"肥岛"的发育具有明显的物种效应,相对梭梭而言,柽柳"肥岛"发育更广、更深,养分聚集更明显,其原因主要是柽柳的半球型树冠更利于保护和捕获凋落物,而较多的凋落物输入与土壤结构和土壤养分间的正反馈机制使柽柳冠下加速的生物地球化学循环能达到更广、更深的范围。灌丛"肥岛"的发育是干旱景观中生物过程与物理过程交互作用的产物,全面揭示其形成机理,探讨其对干旱生态系统结构、功能与动态的影响,需要更系统的研究。
Shrub fertile island＇ is a common feature worldwide in arid regions, and it greatly influences the structure and function of the arid ecosystems. However, the shrub fertile island＇ is species dependent. To examine the species effect on this phenomenon, soils were sampled from canopied area, vertically projected limit of crown margin and interspace between shrubs in Tamarix spp. and Haloxylon ammodendron Bge. communities at an oasis-desert ecotone in south Junggar Basin. Soil samples were analyzed for texture, pH, soil organic matter （ SOM ） , total nitrogen （ TN）, available nitrogen （ AN）,calcium carbonate （CaCO3） and total phosphorus （TP）. Results indicate that （1） fertile islands＇ develop both under Tamarix and H. ammodendron canopies, with the differences of soil properties between islands＇ and interspaces decreasing with depth; （2） there are gradients in biologically-limiting nutrients from islands＇ toward interspaces, whereas the biologically-unlimited elements are more or less or equally distributed in islands＇ relative to interspaces; （3） in terms of the spatial scale, islands＇ of Tamarix spp. may extend out of the canopied area while islands＇ of H. ammodendron are relatively smaller and more shallow than that of Tamarix spp. ; （4） spatial sizes of the islands＇ for different soil indices vary even for the same shrub species. In conclusion, Tamarix islands＇ have more nutrients enriched, larger area and greater depth in comparison to that of H. ammodendron. These differences are greatly due to the different morphologies of the two species, with the hemispheroidal crowns of Tamarix spp. more efficiently capturing and maintaining litter. As a result, the positive feedbacks among higher litter input, soil structure and nutrient storage make the accelerated biogeochemical cycling reach a greater spatial extent under Tamarix spp. To thoroughly clarify the development mechanism and role of the shrub ＇fertile island＇ in the arid ecosystem, however, is of great challenge and needs further work.
出处
《生态学报》
CAS
CSCD
北大核心
2007年第12期5138-5147,共10页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(40571011)
中国科学院知识创新工程资助项目(20042077
20052099)~~
关键词
柽柳
梭梭
肥岛
土壤性状
绿洲-荒漠过渡带
Haloxylon ammodendron
Tamarix spp.
fertile island
soil property
oasis-desert ecotone
作者简介
李君（1975-），男，湖南嘉禾人，博士生，主要从事干旱区生态学研究．E-mail：lijun@ms．xjb．ac．cn
通讯作者E-mail：zey@ms．xjb．ac．cn
