Soil organic matter availability and climate drive latitudinal patterns in bacterial diversity from tropical to cold temperate forests

Abstract

Abstract1. Bacteria are one of the most abundant and diverse groups of micro-organisms and mediate many critical terrestrial ecosystem processes. Despite the crucial ecological role of bacteria, our understanding of their large-scale biogeography patterns across forests, and the processes that determine these patterns lags significantly behind that of macroorganisms.2. Here, we evaluated the geographic distributions of bacterial diversity and their driving factors across nine latitudinal forests along a 3,700-km north-south transect in eastern China, using high-throughput 16S rRNA gene sequencing.3. Four of 32 phyla detected were dominant: Acidobacteria, Actinobacteria, Alphaproteobacteria and Chloroflexi (relative abundance > 5%). Significant increases in bacterial richness and phylogenetic diversity were observed for temperate forests compared with subtropical or tropical forests. The soil organic matter (SOM) mineralisation rate (SOM min , an index of SOM availability) explained the largest significant variations in bacterial richness. Variation partition analysis revealed that the bacterial community structure was closely correlated with environmental variables and geographic distance, which together explained 80.5% of community variation. Among all environmental factors, climatic features (MAT and MAP) were the best predictors of the bacterial community structure, whereas soil pH and SOM min emerged as the most important edaphic drivers of the bacterial community structure. Plant functional traits (community weighted means of litter N content) and diversity resulted in weak but significant correlations with the bacterial community structure.4. Our findings provide new evidence of bacterial biogeography patterns from tropical to cold temperate forests. Additionally, the results indicated a close linkage among soil bacterial diversity, climate and SOM decomposition, which is critical for

Evaluation of the Water Conservation Function of Different Forest Types in Northeastern China

“…leaved species, produces large amounts of litter with a high organic matter content. In natural forest ecosystems, the decomposition of litter into soil organic matter may be the main reason for the increase in soil organic matter [47]. In our study, the five forest types had a stand age of about 50 years, with a similar length of time to accumulate organic matter.…”

“…The value of the comprehensive evaluation directly reflects the water conservation capacity of different forest types [47]. The larger the comprehensive evaluation value, the higher the effect of the corresponding water conservation capacity [48].…”

Cycas micronesica Trees Alter Local Soil Traits

“…Regardless of the causal mechanisms, our results were robust and some trait changes were consistent among the many habitat and soil types. Given the considerable changes in C:N:P and other soil traits, an in-situ C. micronesica tree creates the conditions to increase α-diversity of soil microbiota [33]. The influence of C. micronesica trees on the heterogeneity of soil nitrogen is of particular interest, as nitrogen availability directly affects growth of primary producers in a landscape then exerts cascading effects on food web functioning among many trophic levels [34].…”

Functional traits along a transect

“…Using high‐throughput 16S rRNA gene sequencing, Tian et al. () investigated the geographical distribution of bacterial diversity and found that soil bacterial richness and phylogenetic diversity increased linearly with latitude. Soil pH and substrate availability were the most important edaphic drivers for bacterial community structure along the transect.…”