The life strategy of bacteria rather than fungi shifts in karst tiankeng island-like systems.

Karst tiankeng is a typical terrestrial habitat island-like system, known as an oasis in a degraded karst landscape. However, we know little about the composition, structure, and life strategies of soil microbial communities in the karst tiankeng ecosystem. In this study, we use amplicon sequencing to investigate the soil bacteria and fungi of 26 karst tiankeng in two typical karst tiankeng groups. The results showed that the composition and structure of bacterial and fungal communities were significantly different at two dimensions (among and within the karst tiankeng group). Bacteria showed more sensitivity to variation in the karst tiankeng area and isolation than fungi. With the increase of karst tiankeng area and isolation, the bacterial life strategies shift from K-strategist to r-strategist, likely due to the changes in soil properties (total phosphorus, Ca, and soil water content). Abundant and rare taxa play different roles in karst tiankeng ecosystems; abundant taxa serve a key role in nutrient cycles and life strategy shifts by occupying the key status in networks. Considering the key role of soil microbes in ecosystems, more attention must be paid to the impact of habitat loss on soil microbial life strategies, particularly in the ecological impact of life strategies change of abundant and rare taxa.

Importance: These findings highlight that habitat loss or fragmentation induces a shift in microbial life strategies and improves our understanding of the composition and biogeography of karst ecosystem microorganisms.