钱江源国家公园体制试点区水稻田土壤微生物群落的格局及其驱动机制

Spatial patterns of rice paddy microbial communities and the associated drivers in Qianjiangyuan National Park system pilot

建立健全国家公园体制对于保护自然生态系统的完整性与生物多样性具有重要意义。作为首批试点单位之一,钱江源国家公园体制试点区(以下简称“钱江源”)率先开展了集体林地地役权改革,并取得了良好效果。然而地役权改革是否以及如何影响钱江源土壤及其微生物,目前还缺乏系统评估。本研究对钱江源4个片区中不同改革模式下的水稻田表层土壤进行取样,每个片区内均采集4种模式的水稻田:公园内改革、公园内弃耕地、公园内未改革以及公园外未改革。利用高通量测序研究土壤微生物群落的组成与结构,并利用多元统计分析等剖析塑造微生物群落空间格局的驱动因素。结果发现,与其他3类土壤相比,弃耕地具有更低的氮磷等营养元素含量和重金属元素含量;其他3类土壤的理化性质则较为相似。在微生物方面,细菌群落以变形菌门(48.57%)和酸杆菌门(31.62%)为主;真菌群落以子囊菌门(78.31%)和担子菌门(16.38%)为主。不同模式下的细菌群落差异较大,尤其是弃耕地与其他3类均具有显著性差异,其他3类则较为相似。真菌群落的变异相对较小,仅公园外未改革和弃耕地间具有显著差异。细菌群落组成的空间变异与土壤环境因子显著相关,其中具有主要影响的前5个环境因子分别是pH、铬、全氮、有效磷和有机质。真菌群落组成的空间变异与土壤环境因子间未发现显著相关性。中性群落模型分析发现,中性过程对细菌和真菌群落组成差异的形成均有重要影响。综上,初步认为,存在水稻种植的情况下,地役权改革尚未对水稻田土壤及其微生物起到显著影响;放弃种植的弃耕地则可能已经处在再野化的初期阶段。因此,地役权改革是否以及如何影响长期耕作土壤的恢复,还需要结合长期的综合监测,才能作出更为科学合理的判断。

Aims:The establishment of national parks is crucial in protecting the integrity of natural ecosystems and biodiversity.As one of the first ten pilots,the Qianjiangyuan National Park system pilot(hereafter referred to as Qianjiangyuan)has developed the easement-inspired adaptive management and achieved remarkable outcomes.However,it remains unclear how this creative management might influence the soil microorganisms and systematic evaluation is in need.Methods:We took Qianjiangyuan as the study area and collected surface soils from rice paddies in the different districts and under different management types.Four management types were included,namely,reformed land within the park,abandoned land within the park,unreformed land within the park,and unreformed land outside the park.We employed high-throughput sequencing techniques to characterize the community composition and structure of both bacteria and fungi.We then analyzed the driving forces behind the spatial patterns of bacterial and fungal communities.Results:Compared to the other three types of lands,contents of soil nitrogen and phosphorus and heavy metals were relatively low in the abandoned land,but they were similar in the other three types.The bacterial communities were dominated by Proteobacteria(48.57%)and Acidobacteria(31.62%),while the fungal communities were dominated by Ascomycota(78.31%)and Basidiomycota(16.28%).Bacterial communities varied largely in lands under different management types,with significant difference between abandoned land and other three types,while the other three types were similar.Fungal communities showed slight variation,with significant difference being identified only between abandoned land and outside unreformed land.We found significant correlation between soil environmental factors and spatial variation of bacterial communities.The most important five factors driving bacterial spatial patterns were p H,chromium,total nitrogen,available phosphorus,and organic matter.However,no significant correlation was detected between fungal communities and soil environmental factors.Analysis of neutral community models found that neutral processes played an important role in the spatial distribution of both bacterial and fungal communities.Conclusion:Based on these findings,we conservatively conclude that no significant impacts have been produced by land reforming policy so far.In contrast,the abandoned land may have begun rewilding.Therefore,long-term monitoring is needed to comprehensively assess whether and how ecological protection easement will impact the recovery of rice soils.