Soil organic matter quantity and quality shape microbial community compositions of subtropical broadleaved forests

Abstract

As two major forest types in the subtropics, broadleaved evergreen and broadleaved deciduous forests have long interested ecologists. However, little is known about their belowground ecosystems despite their ecological importance in driving biogeochemical cycling. Here, we used Illumina MiSeq sequencing targeting 16S rRNA gene and a microarray named GeoChip targeting functional genes to analyse microbial communities in broadleaved evergreen and deciduous forest soils of Shennongjia Mountain of Central China, a region known as 'The Oriental Botanic Garden' for its extraordinarily rich biodiversity. We observed higher plant diversity and relatively richer nutrients in the broadleaved evergreen forest than the deciduous forest. In odds to our expectation that plant communities shaped soil microbial communities, we found that soil organic matter quantity and quality, but not plant community parameters, were the best predictors of microbial communities. Actinobacteria, a copiotrophic phylum, was more abundant in the broadleaved evergreen forest, while Verrucomicrobia, an oligotrophic phylum, was more abundant in the broadleaved deciduous forest. The density of the correlation network of microbial OTUs was higher in the broadleaved deciduous forest but its modularity was smaller, reflecting lower resistance to environment changes. In addition, keystone OTUs of the broadleaved deciduous forest were mainly oligotrophic. Microbial functional genes associated with recalcitrant carbon degradation were also more abundant in the broadleaved deciduous forests, resulting in low accumulation of organic matters. Collectively, these findings revealed the important role of soil organic matter in shaping microbial taxonomic and functional traits.

Seasonal soil microbial responses are limited to changes in functionality at two Alpine forest sites differing in altitude and vegetation

“…Interestingly, Ding, et al . 25 , also found that the soil bacterial network of a broadleaved evergreen forest presented a higher resistance to environmental changes than that of a broadleaved deciduous forest. On the other hand, we discovered that most of the OTUs identified as module hubs and connectors (generalists) by the Zi-Pi plot (Fig.…”

“…48 , comparing the soil microbial communities of a natural mature forest with those of a natural secondary forest, found a strong positive correlation between the soil bacterial community structure and the GeoChip-based functional community composition. However, there are other studies showing no significant correlations between microbial taxonomic and functional composition 25, 39 , which is explained as a consequence of the functional redundancy of soil microbial communities 49 . The contradictory results may be caused by differences in terms of techniques, scale or ecosystem investigated 22 .…”

“…The subalpine site R presented increased levels of C, N and other nutrients respect to the submontane site M, which can be explained by the higher recalcitrance of coniferous litter (high C/N ratio and lignin content as well as low pH 36 ), producing a greater C sequestration and lower nutrient immobilization rates 17 . Furthermore, some surveys, comparing evergreen and deciduous forests, have indicated that evergreen forests accumulate more SOM in the forest floor than deciduous forests located in similar climatic zones 25 . Therefore, the increased levels of C and other nutrients detected at site R may contribute to enhance microbial growth and would explain the higher bacterial and fungal abundance detected at this forest site, as we formerly explained 17 .…”

“…Ding, et al . 25 found significant differences in soil bacterial (based on Illumina amplicon sequencing of 16S rRNA genes) and microbial functional (GeoChip-based) community composition and diversity between shrubland and coniferous forests at the forest timberline. While, Shen, et al .…”

A hollow bacterial diversity pattern with elevation in Wolong Nature Reserve, Western Sichuan Plateau

“…3 The network of the forest soil bacteria. National Nature Reserve (Ding et al 2015). However, broadleaved forestry soil contained more Actinobacteria hubs, known as copiotrophic bacteria preferentially living in abundant resources (Ramirez et al 2012), suggesting that the key species of soil can be disparate in different forestry ecosystem.…”