Biogeographical Patterns And Its Environmental Interpretation Of Plant And Soil Microbial Diversity In Temperate Desert Regions Of China

Temperate deserts ecosystems cover more than 20%of the terrestrial area of China,which is one of the most critically fragile ecosystems in China.It is widely reported that these desert ecosystems are particularly vulnerable to current and future climate and land-use changes.However,the large-scale biogeographical patterns and its drivers of plant and soil microbial species diversity in temperate desert regions of china have rarely been explored synchronously.Meanwhile,to date the internal links between plant and soil microbial communities in these regions still remain unclear.To evaluate the drivers of plant and soil microbial diversity,and the relationships between plant and soil microbes,a total of 855 plant plots and 84 soil samples were sampled from the typical temperate desert regions of China.Both soil bacterial and fungal species diversity and community compositions were measured through high throughput sequencing bacterial 16S rRNA gene and fungal ITS data.Meanwhile,both plant and microbial beta diversity were decomposed into two components:species replacement(species turnover)and nestedness components.The results are as following:(1)Plant,soil bacterial and fungal alpha diversity exhibited significant latitudinal and longitudinal gradients,which were significantly correlated with latitude and longitude.Distance-decay curves demonstrated that both plant,soil bacterial and fungal community similarity significanlty decreased with increasing geographic distance.These results demonstrate the apparent biogeographical patterns of plant and soil microbial diversity in temperate desert regions of China.(2)Habitat,climate and spatial factors together explained 16.3%-65.1%of the variation for plant alpha and beta diversity,and both three groups of variables can individually contribute significant variation.Environmental factors individually explained 7.5%-21.4%the variation in plant alpha and beta diversity,respectively.Notably,a total of 2.6%-6.2%variation in plant alpha and beta diversity were individually explained by spatial factors.Although climate individually explained the largest fraction of variation in plant alpha diversity,habitat factors were relatively more important in explaining plant beta diversity.(3)Habitat,climatic and spatial factors together explained 45.3%-64.1%of the variation in soil bacterial and fungal alpha diversities.While plant,habitat,climatic and spatial factors together contributed 23.2%-36.7%of the variation in soil bacterial and fungal beta diversities.Notably,environmental variables individually explained more variation for both alpha and beta components of soil bacterial and fungal diversities rather than spatial factors.Furthermore,plant factors individually explained the largest fraction of the variation in soil bacterial beta diversities,whereas spatial factors had more powerful effect on soil fungal beta diversity.(4)Species replacement components almost contributed all variance for plant,soil fungal and bacterial beta diversities rather than species nestedness components.Additionally,both the responses of plant,soil fungal and bacterial beta diversities to environmental and spatial variables were greatly accordant with that of species replacement components.This may imply that environmental and spatial factors regulate plant and soil microbial community compositions through influencing these species replacement for biomes.(5)Both soil bacterial and fungal diversities were significantly coupled with plant diversity at alpha and beta level.Structural equation models further demonstrated that plant alpha diversity had no direct correlation with soil bacterial and fungal alpha diversities,whereas plant beta diversity can individually regulate both soil bacterial and fungal beta diversities.In addition,soil bacterial beta diversity had strongly correlation with plant beta diversity than that with soil fungal beta diversity.Taken together,this work firstly confirms that the biogeographic patterns of plant and soil microbial species diversities were shaped by contemporary environment,spatial and other unknown factors together,while contemporary environment play more powerful role.Our results also propose that other unmeasured variables,such as groundwater depth and human activities,may have non-negligible influence on biodiversity in temperate desert regions of China.This work also provides robust evidence that the direct links between plant and soil microbial species diversities were significant at beta level,but not at alpha level.Plant beta diversity may be the limited factor for soil bacterial and fungal beta diversities.Finally,this study emphasizes that the biogeographic patterns and its drivers of plant and soil microbial species diversities may differ remarkably depending on inquiry scales,biological biota and habitat types,soil microbial and plant biodiversity were driven by multiple ecological processes in temperate deserts of China.Furthermore,the links between plant and soil microbial communities may be influenced by microbial traits,environmental gradient and inquiry scales.