生物土壤结皮对种子萌发和幼苗建植的影响研究进展

Research progress on the effect of biological soil crust on seed germination and seedling establishment

生物土壤结皮(BSC)在陆地生态系统中具有重要的生态地位,尤其是旱地生态系统中,BSC占据了种子植物之间的广阔地面。因此,BSC的发展必然影响种子植物更新过程与植被空间格局;但其作用方式、影响程度等因相关研究涉及多气候要素、土壤类型、BSC组成物种和种子植物物种的差异及其不同组合,导致目前的研究结论存在广泛争议。研究综合论述了BSC改变地表微形态对种子传播过程的影响;BSC改变土壤特性(物理、化学、生物学)对种子萌发和幼苗存活与建植等关键环节的影响;并结合种子形态特征及种子萌发、幼苗建植的性状等,综合分析了BSC对种子传播、种子萌发与幼苗建植等更新过程的潜在影响机理;探讨了目前研究矛盾性结论产生的原因。总体来说,深入研究并全面揭示BSC对种子植物更新过程的影响,应加强学科交叉,将分子生物学、植物生理学、生物化学等微观研究,与遥感、野外生态因子过程监测、控制实验等宏观、中观研究结合,从机理到过程方面动态研究BSC对种子植物更新过程的影响,并引入水文模型、气候模型、种群动态模型等模型预测方法,研究气候变化、各类干扰频发的情景下,BSC对种子传播、萌发及幼苗建植过程的潜在影响,以期促进对BSC与种子植物间相互关系的研究,加深对干旱脆弱生态系统植被发展规律的认识。

Biological soil crust(BSC)plays a very important role in the terrestrial ecosystems,especially in the dryland ecosystems,where BSC occupies open ground among seed plant patches.Thus,the development of BSC must be an important factor that influences the seed plant recruitment process and vegetation spatial distribution pattern.However,in the present studies,there are lots of debates about the effect of BSC on seed dispersal and germination,seedling emergence and establishment.The reason for these arguments is that the effects of BSC on seed plants depend upon comprehensive impact of multiple factors,such as different climatic conditions,soil types,species compositions of BSC,species compositions of seed plants and the different combinations of these factors.In order to well understand the research progress on the effect of BSC on seed germination and seedling establishment,we searched the literatures about the relationships among BSC and seed dispersal,germination,seedling emergence,establishment.The related literatures published both in English and Chinese were searched.We reviewed the influence of the surface micromorphology caused by BSC on seed dispersal;the effect of soil characteristics(physical,chemical and biological)changed by BSC on seed germination,seedling emergence,survival and establishment;the mechanism of the influence of BSC on seed dispersal,seed germination and seedling establishment,based on the seed shape characteristics,seed germination and seedling establishment traits.The potential reasons for contradictory experimental results were analyzed.In generally,to conduct in-depth research,multidisciplinary experimental approaches should be used.The microscopic studies such as molecular biology,plant physiology,biochemistry and the macro&medium scale studies such as remote sensing,field ecological factor process monitoring,controlled experiments should be combinatively used to study the mechanism and process about the BSC influence on the seed dispersal,germination and seedling establishment.At the same time,under the background of global climate change and frequent occurrence of disturbance,it is better to introduce simulation and prediction methods in related study fields such as hydrological model,climate model,population dynamic model and others to predict procedural effects of BSC on seed dispersal,seed germination and seedling establishment.And then,this novel study approaches would promote the study on the relationship between BSC and seed plants,and deepen the understanding of the law of vegetation development in arid fragile ecosystems.