Abstract
Soil microbes have a major impact on microbial function in extreme environments, such as deserts, where environmental factors such as salinity and soil water act as strong filters to community structure. In fact, environmental filtering in these extreme environments can occur over even small gradients in soil depth, which is often overlooked, but important in the functioning of these systems. We leveraged a 200-km desert soil salinity gradient to test the relationships between microbial community structure and function (i.e., enzymatic activity) at different soil depths. Surprisingly, differences in soil bacterial and fungal community structure were not linked to differences in enzymatic activity, implying that soil microbial communities have a high degree of functional redundancy among soil depths. However, we found that the effects of soil depth (at the scale of meters) were just as important as the effects of geographic distance (on the scale of kilometers) on soil bacterial and fungal community structure, while the vertical variability in enzymatic activity along soil depth was largely attributed to the increase in heterogeneity of soil properties (i.e., soil texture, water content, and pH). Although contrasting assembly processes determine community structure and function, these findings suggest that soil depth restructures microbial community structure and function in extreme environments. Our data highlight that soil conservation efforts in arid ecosystems should consider soil depth as a key attribute in the face of ongoing desertification in many ecosystems.
Significance Soil microbes mediate many ecosystem functions in extreme environments, where environmental factors act as strong filters to community structure. Environmental filtering can occur over even the small scale along soil depth profiles, which is often overlooked, but important in regulating ecosystem functioning. Here, we investigate the structure-function relationships of soil microbial communities along soil-depth profiles in the Taklamakan desert. We show that soil depth restructures soil microbial community structure and function. This work highlights that soil conservation efforts in arid ecosystems should consider soil depth as a key attribute in the face of ongoing desertification in many ecosystems.
Competing Interest Statement
The authors have declared no competing interest.