A review of diversity-stability relationship of soil microbial community: what do we not know?

The impact of decreased biodiversity on ecosystem stability, or the diversity-stability (D-S) relationship, is one of the major concerns of modern ecological studies. Studies on the D-S relationship for soil microbial communities began in 2000 when the fumigation method was developed to generate different levels of soil microbial biodiversity. The studies used various measures and levels of biodiversity, and covered several functional parameters. Due to the lack of general concepts and reliable approaches to define microbial species, studies on the D-S relationship of soil microbial communities concentrate on genetic diversity and functional diversity more than species diversity. Contradictory results were observed in various studies on D-S relationship with possible factors affecting or even changing the directions of the D-S relationship including: (1) the methods of stability measurement, (2) the techniques in microbial diversity measurement, (3) the measures and levels of diversity, (4) the type and strength of disturbance, (5) the traits of functions, and (6) the hidden treatments stemming from diversity manipulation. We argue that future studies should take diversity, species composition and interaction, and soil environmental conditions holistically into account in D-S studies to develop modeling to predict soil functional stability. We also suggest that studies should be carried out on a wider range of disturbance types and functional parameters, and efforts be shifted towards long-term field studies.