细根对降水变化响应的meta分析

Response of fine roots to precipitation change: A meta-analysis

细根对土壤水分含量变化十分敏感,增加和减少降水直接影响土壤水分含量。为探索细根对降水变化的响应,该文从48篇已发表的国内外研究论文中搜集到202组数据,通过meta分析的方法揭示细根生物量、生产量、周转率、根长度密度、比根长及细根分解对增加和减少降水的一般响应规律,用加权响应比评价降水对细根各指标的影响效应,降水变化对细根分解的影响用土壤微生物生物量碳的响应比衡量。结果表明:1)不同类型植物的细根对降水变化的响应程度不同,灌木细根的响应强于乔木。2)细根各指标对降水变化的响应存在土层空间异质性,并且降水变化量为50%时细根响应最显著。降水增加50%时,显著增加20–40 cm土层的细根生物量和0–10 cm土层的细根比根长,降水减少50%时,显著减少20–40 cm土层的细根生产量和增加0–10 cm土层的细根根长度密度。3)降水变化实验持续时间的长短会影响细根的响应程度,短期实验中细根通过形态适应对降水变化做出应对,而长期实验中细根通过重新分配生物量对降水变化做出响应。4)增加降水促进了细根养分归还,致使土壤微生物得到了充足的底物资源,提高了自身活性,使细根分解加快。

Aims The response of fine roots to soil moisture is very sensitive. Climate change scenarios predict changes in precipitation which influence soil moisture directly. Plants optimize resource acquisition by fine root morphological plasticity and biomass redistribution when soil moisture changes. Therefore, it is important to study the effect of precipitation increase and decrease on fine roots and reveal the response of ecosystem carbon cycling to global climate change. Methods We collected 202 sets of data from 48 published domestic and foreign articles, and analized the responses of fine root biomass, production, turnover, root length density, specific root length and soil microbial biomass carbon which reflects fine root decomposition dynamic to precipitation change by the meta-analysis. RR＋＋ （weighted response ratio） was used to quantify the effect size of the response of fine roots to precipitation change.Important findings （1） The significance and magnitude of the precipitation effects on fine roots varied among plant types. Shrub fine roots had stronger response than tree fine roots. （2） The response of fine roots differed across soil depth. Fine root had most significant responses when the precipitation increased or decreased 50%. A 50% increase in precipitation had a significant positive impact on both fine root biomass in 20-40 cm soil and specific root length in 0-10 cm soil depth. A 50% decreased in precipitation had a significant negative impact on fine root production in 20-40 cm soil but positive impact on root length density in 0-10 cm soil. （3） The duration of experiment affected the response of fine roots, fine roots responded to precipitation changes （increase and decrease） by morphological plasticity in short-term experiments, and by biomass redistribution in long-term experiments. （4） Increasing precipitation contributed to the nutrient release of fine roots, because soil microbes accelerated the decomposability of fine roots due to sufficient substrate resources stimulated their own activity.