Abstract:

Aims: Understanding the distribution and drivers of soil fauna diversity as well as their ecological functions have become areas of cutting-edge research in modern geoscience and ecology. Here, we briefly introduce the latest progress in this field, discuss present research limitations and uncertainties, and offer promising research directions in future studies of soil fauna.
Progresses: Many studies have described the global distribution of representative soil fauna taxa diversity and abundance, such as that of earthworms. Research on soil fauna distribution and ecological function in China has also flourished with many large scale, intensive sampling studies in the past 10 years (especially for earthworms and nematodes). Based on a literature review, we observed that there were two main distribution patterns of soil fauna diversity across latitudes. Diversity was found to be highest either at low-latitude tropical zones or at mid-latitude temperate zones; while changes in soil fauna abundance and diversity can be consistent, non-related, totally different, and even opposite. Precipitation, plant productivity and soil organic matter were the critical drivers of soil fauna distribution, but their influences varied with soil faunal taxon. The major ecological functions of soil fauna include improving soil physical structure, facilitating nutrient cycling and organic carbon stabilization, and enhancing plant health. The concept of multifunctionality of soil fauna has been proposed by soil ecologist to fully measure these multi-dimensional ecological functions, but it still faces many challenges.
Prospect: The drivers of soil fauna distribution are not simply predicted from the variation pattern of soil faunal community characteristics across latitudes, longitudes or altitudes. Rather, we suggest that drivers of the soil fauna distribution should be explored within a multi-dimensional spatial-temporal framework based on a combination of geological and ecological history as well as “latitude & longitude-altitude-distance to coast”. The distribution pattern of soil fauna may critically influence their potential ecological functions; however, the prediction and simulation of soil fauna distribution mainly relied on data-driven empirical models, and the results were not conclusive. Thus, the application of theories such as metabolic ecology deserves more attention. Research on the relationship between soil fauna diversity and function is in the preliminary stages; focusing on functional diversity and exploring the redundancy mechanism of taxonomic diversity could link soil fauna diversity and function. We propose to understand soil fauna diversity and function under specific condition of space and time, as well as the context of the whole soil food web and its connection with plants. There are two promising directions for further research: (1) illustrating the large uncertainties that human activity and climate change may bring to soil fauna studies; (2) developing precision manipulation approaches of soil fauna community to ultimately link soil fauna multifunctionality with human well-being.

Key words: soil fauna diversity, multifunctionality, human activity, global change, ecosystem service