增温对森林细根生长、死亡及周转特征影响的研究进展

Effects of warming on fine root growth,mortality and turnover:a review

细根是根系中最活跃和最敏感的部分,在森林生态系统生物地球化学循环中发挥着十分重要的作用。细根生长和周转会对植物根系碳进入土壤的通量产生强烈的影响。全球变暖对地下生态过程的影响已成为全球变化背景下关注的热点问题,细根生长动态对全球变暖作何响应将直接影响到生态系统的碳平衡。该文就增温对森林细根生长、死亡、生物量及周转的影响的研究进展进行综述,以期揭示增温对森林细根生长动态的影响。目前大部分研究认为增温会通过改变土壤含水率、养分有效性以及新近光合产物的分配等指标来影响细根的生长和死亡,加快细根周转过程,进而导致细根生物量降低。但细根生长受诸多因素的影响,使得增温对细根影响的研究结果因树种、区域、增温方式等因素的影响存在不一致的结论。因此综合分析增温条件下森林细根的响应对研究地下生态学过程至关重要。今后还应加强以下方面的研究:(1)根据各增温方法的优缺点比较不同增温方式以及短期、长期增温实验对细根生长动态和地上部分影响的研究;(2)结合多种细根观测手段及实验方法综合分析增温对细根生长动态的影响,同时加强增温对细根序级结构影响的研究;(3)加强增温与养分、水分、CO_(2)等的交互作用对细根生长动态影响的研究;(4)重点关注增温对不同土层尤其是深层土壤中细根生长动态影响的研究;(5)深入研究细根-土壤-微生物三者间相互关系对增温的潜在响应。

Fine roots are the most active and sensitive part of the root system,and play an important role in the biogeochemical cycles of forest ecosystems.Fine root growth and turnover have a strong impact on the root carbon flux into soil.The effect of global warming on below-ground ecological processes has become a hot issue in global change research,and the response of fine root dynamics to warming will directly affect the carbon balance of forest ecosystems.In this paper,the effects of warming on fine root production,mortality,biomass and turnover are reviewed to reveal the effects of warming on fine root dynamics.Generally,warming affects the fine root production and mortality by changing soil moisture,nutrient availability and distribution of recent photosynthetic products,accelerates fine root turnover process,and then reduces fine root biomass.However,fine root growth is affected by many factors,making the research results of the impact of warming on fine roots inconsistent among different studies,due to the difference in tree species,regions,warming methods and other factors.Therefore,comprehensively analyzing the response of forest fine roots under warming is very important for studies on below-ground ecological processes.In the future,we call for more research in the following aspects:(1)according to the advantages and disadvantages of each warming method,compare the effects of different warming methods and warming durations on the growth dynamics of fine roots and above-ground parts;(2)combined with various fine root observation and experimental methods,comprehensively analyze the effect of warming on fine root growth dynamics,and strengthen the research on the effect of warming on fine root order structure;(3)strengthen the research on the interaction of warming and nutrient,water and CO_(2)on fine root growth dynamics;(4)focus on the effects of warming on fine root dynamics in different soil layers,especially in deep soils;and(5)deeply study the potential response of the relationship among fine roots,soils and microorganisms to warming.