Data from: Mammalian engineers drive soil microbial communities and ecosystem functions across a disturbance gradient

The effects of mammalian ecosystem engineers on soil microbial communities and ecosystem functions in terrestrial ecosystems are poorly known. Disturbance from livestock has been widely reported to reduce soil function, but disturbance by animals that forage in the soil may partially offset these negative effects of livestock, directly and/or indirectly by shifting the composition and diversity of soil microbial communities. Understanding the role of disturbance from livestock and ecosystem engineers in driving soil microbes and functions is essential for formulating sustainable ecosystem management and conservation policies.
We compared soil bacterial community composition and enzyme concentrations within four microsites: foraging pits of two vertebrates, the indigenous short-beaked echidna (Tachyglossus aculeatus) and the exotic European rabbit (Oryctolagus cuniculus), and surface and subsurface soils along a gradient in grazing-induced disturbance in an arid woodland.
Microbial community composition varied little across the disturbance gradient, but there were substantial differences among the four microsites. Echidna pits supported a lower relative abundance of Acidobacteria and Cyanobacteria, but a higher relative abundance of Proteobacteria than rabbit pits and surface microsites. Moreover, these microsite differences varied with disturbance. Rabbit pits had a similar profile to the subsoil or the surface soils under moderate and high, but not low disturbance.
Overall, echidna foraging pits had the greatest positive effect on function, assessed as mean enzyme concentrations, but rabbits had the least. The positive effects of echidna foraging on function were indirectly driven via microbial community composition. In particular, increasing activity was positively associated with increasing relative abundance of Proteobacteria, but decreasing Acidobacteria.
Our study suggests that soil disturbance by animals may offset, to some degree, the oft-reported negative effects of grazing-induced disturbance on soil function. Further, our results suggest that most of this effect will be derived from echidnas, with little positive effects due to rabbits. Activities that enhance the habitat for echidnas or reduce rabbit populations are likely to have a positive effect on soil function in these systems.

陆生生态系统中，哺乳动物生态系统工程师（mammalian ecosystem engineers）对土壤微生物群落与生态系统功能的影响迄今仍未得到充分阐明。已有大量研究表明，家畜活动造成的干扰会削弱土壤生态功能，但在土壤中觅食的动物所引发的干扰，可通过直接或间接改变土壤微生物群落的组成与多样性，部分抵消家畜活动带来的负面影响。阐明家畜与生态系统工程师所引发的干扰在驱动土壤微生物群落及生态功能变化中的作用，对于制定可持续的生态系统管理与保护政策至关重要。
本研究在一片干旱林地中，沿放牧诱导干扰梯度设置了四类微生境：两种脊椎动物的觅食坑——本土短吻针鼹（*Tachyglossus aculeatus*）与外来欧洲野兔（*Oryctolagus cuniculus*）的觅食坑，以及表层与底层土壤，对其中的土壤细菌群落组成与酶浓度进行了对比分析。
微生物群落组成在干扰梯度上的变化幅度极小，但四类微生境之间却存在显著差异。与野兔坑及表层微生境相比，针鼹觅食坑中的酸杆菌门（Acidobacteria）和蓝细菌门（Cyanobacteria）相对丰度更低，而变形菌门（Proteobacteria）相对丰度更高。此外，微生境间的差异会随干扰程度发生变化：在中度和高强度干扰下，野兔坑的群落特征与底层土壤或表层土壤相似，但在低强度干扰下则并非如此。
总体而言，以平均酶浓度衡量的生态功能在针鼹觅食坑中受到的正向影响最大，而野兔觅食坑的正向影响则最弱。针鼹觅食对生态功能的正向影响，是通过微生物群落组成间接介导的。具体而言，酶活性的提升与变形菌门相对丰度的增加以及酸杆菌门相对丰度的减少呈显著正相关。
本研究表明，动物引发的土壤干扰可在一定程度上抵消已有研究广泛报道的、放牧诱导干扰对土壤生态功能的负面影响。此外，研究结果显示，这类抵消作用主要源自针鼹的活动，野兔活动带来的正向影响则微乎其微。因此，改善针鼹栖息地或减少野兔种群数量的举措，有望提升该类生态系统的土壤生态功能。