基于Meta分析研究毛竹入侵致土壤pH提升及养分和微生物群落结构的变化

诸多研究发现毛竹入侵周围林分提高土壤pH，但未见统计性描述报道。为此，本研究将通过大数据分析证实此现象的普遍性以及探究伴随的土壤养分和微生物变化。本研究收录包含毛竹入侵有关土壤pH变化的42篇文献总计101组数据，采用整合分析方法（Meta-analysis）进行深入探讨。在研究土壤养分变化时，本文还结合了团队采集的12个毛竹入侵带的样地数据总计92个样品18组数据进行分析。结果表明，在所有的数据组中，84.9%的土壤在经过毛竹入侵后其pH有不同幅度的提升，说明毛竹入侵周围林分普遍提高土壤pH；土壤pH增加幅度随入侵阶段、毛竹纯林时间增加而增加，随土层深度增加而降低；入侵针叶林致土壤pH增加的幅度高于阔叶林。入侵的毛竹纯林与原生林相比，总体上显著降低（P<0.05）了土壤全氮（-15.9%）、硝态氮（-21.7%）、全碳（-2.0%），却增加（P<0.05）了土壤有效磷（+54.9%）、铵态氮（+14.7%）和碱解氮（+8.2%）。对27篇包含微生物数据的文献进行整合分析，结果表明毛竹入侵改变了微生物群落结构，增加（P<0.05）了放线菌门相对丰度（+25.86%），而降低（P<0.05）了酸杆菌门（-15.49%）、浮霉菌门（-26.66%）、拟杆菌门（-22.58%）的相对丰度。本研究通过Meta分析证明毛竹入侵周围林分提高土壤pH为普遍自然现象，结合土壤硝态氮和铵态氮指标的变化推测了导致土壤pH提升的可能机制，毛竹入侵提高了土壤细菌和真菌多样性，表明入侵对土壤微生物具有正反馈效应。

Bamboo Invades Surrounding Forest Increased Soil pH, Changed Soil Chemical Nutrient and Microbial Community： A Meta-Analysis

【Objective】In the past decades, the surface area of land covered by bamboo (Phyllostachys edulis) in China has rapidly increased. Many studies on bamboo forests have highlighted that bamboo invasion is associated with an increase in the soil pH. The objective of this study was to verify the mechanism by which bamboo invasion increased soil pH as well as to explore the accompanying soil nutrients and microbial properties change trend.【Method】A meta-analysis was conducted to test whether the invasions of bamboo into the adjacent forests lead to an increase in soil pH. The changes in soil nutrients and microbial community after the bamboo invasion were also analyzed. In this meta-analysis, 101 sets of data from 42 studies were collected. Besides data from references, 18 sets of data from 12 plots of bamboo invasion zones from experimental plots were also used to analyze soil pH and nutrient change.【Result】Overall, the results showed that in all the data sets, 84.9% of the soil pH increased by different amplitude after the bamboo invasion. The magnitude of soil pH increased with invasion time but decreased with soil depth. Also, the increase of soil pH in a coniferous forest (CF) was higher than that in a broadleaf forest (BL). The invasive pure bamboo forest (BB) decreased soil total nitrogen (-15.9%, P<0.05), nitrate nitrogen (-21.7%, P<0.05), total organic carbon (-2.0%, P<0.05), but increased soil available phosphorus (+54.9%, P<0.05), ammonia nitrogen (+14.7%, P<0.05) and alkali-hydrolyzable nitrogen (+8.2%, P<0.05) compared with the original forest. In addition, the bamboo invasion also changed soil microbial community structure and the relative abundance of Actinomycetes was increased (+25.86%, P<0.05), while that of Acidobacteria (-15.49%, P<0.05), planctomycetes (-26.66%, P<0.05) and Bacteroidetes (-22.58%, P<0.05) was decreased. Based on the meta-analysis results, the ammonia nitrogen was increased while nitrate nitrogen decreased after the bamboo invasion. It could be inferred that the process of ammonification (NH3+H+→NH4+) was improved while nitrification (NH4++2O2→NO3-+H2O+2H+) was suppressed. Therefore, the possible mechanism of soil pH increase was attributed to the reduction of the accumulation of soil protons released during nitirifcation.【Conclusion】Bamboo invasion into adjacent forests increased soil pH, altered soil chemical properties and microbial community. The effect of bamboo invasion on soil pH is a common phenomenon and the possible mechanism for increasing pH may be related to changes in soil ammonia nitrogen and nitrate nitrogen concentrations.