Department of Natural Resources & Environmental Management, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
Institute of Pacific Islands Forestry, USDA Forest Service, Hilo, HI 96720, USA.
Sci Rep. 2019 Oct 11;9(1):14681. doi: 10.1038/s41598-019-48922-7.
Nonnative, invasive feral pigs (Sus scrofa) modify habitats by disturbing soils and vegetation, which can alter biogeochemical processes. Soil microbial communities drive nutrient cycling and therefore also play important roles in shaping ecosystem structure and function, but the responses of soil microbes to nonnative ungulate removal remains poorly studied. We examined changes in the soil bacterial community over a ~25 year chronosequence of feral pig removal in tropical montane wet forests on the Island of Hawai'i. We extracted bacterial eDNA from soil samples collected inside and outside of ungulate exclosures along this chronosequence and sequenced the eDNA using the Illumina platform. We found that ungulate removal increased diversity of soil bacteria, with diversity scores positively correlated with time since removal. While functional and phylogenetic diversity were not significantly different between pig present and pig removed soils, soil bulk density, which decreases following the removal of feral pigs, was a useful predictor of dissimilarity among sites and correlated to changes in functional diversity. Additionally, increases in soil porosity, potassium, and calcium were correlated to increases in functional diversity. Finally, sites with greater mean annual temperatures were shown to have higher scores of both functional and phylogenetic diversity. As such, we conclude that feral pigs influence overall bacterial community diversity directly while influencing functional diversity indirectly through alterations to soil structure and nutrients. Comparatively, phylogenetic differences between communities are better explained by mean annual temperature as a climatic predictor of community dissimilarity.
非本地、入侵的野猪（Sus scrofa）通过干扰土壤和植被来改变栖息地，这会改变生物地球化学过程。土壤微生物群落驱动着养分循环，因此在塑造生态系统结构和功能方面也起着重要作用，但土壤微生物对非本地有蹄类动物去除的响应仍研究甚少。我们在夏威夷热带高山湿润森林中，通过大约 25 年的野猪去除时间序列，研究了土壤细菌群落的变化。我们从沿着这个时间序列的无脊椎动物围栏内外的土壤样本中提取细菌的 eDNA，并使用 Illumina 平台对 eDNA 进行测序。我们发现，无脊椎动物的去除增加了土壤细菌的多样性，多样性评分与去除后的时间呈正相关。虽然功能和系统发育多样性在有猪和无猪土壤之间没有显著差异，但随着野猪的去除，土壤容重降低，这是站点之间差异的一个有用预测因子，并与功能多样性的变化相关。此外，土壤孔隙度、钾和钙的增加与功能多样性的增加相关。最后，年平均温度较高的地点表现出较高的功能和系统发育多样性得分。因此，我们得出的结论是，野猪通过改变土壤结构和养分间接影响功能多样性，从而直接影响整体细菌群落多样性。相比之下，群落之间的系统发育差异可以通过平均年温度作为群落差异的气候预测因子来更好地解释。
