Relating belowground microbial composition to the taxonomic, phylogenetic, and functional trait distributions of trees in a tropical forest

Abstract

The complexities of the relationships between plant and soil microbial communities remain unresolved. We determined the associations between plant aboveground and belowground (root) distributions and the communities of soil fungi and bacteria found across a diverse tropical forest plot. Soil microbial community composition was correlated with the taxonomic and phylogenetic structure of the aboveground plant assemblages even after controlling for differences in soil characteristics, but these relationships were stronger for fungi than for bacteria. In contrast to expectations, the species composition of roots in our soil core samples was a poor predictor of microbial community composition perhaps due to the patchy, ephemeral, and highly overlapping nature of fine root distributions. Our ability to predict soil microbial composition was not improved by incorporating information on plant functional traits suggesting that the most commonly measured plant traits are not particularly useful for predicting the plot-level variability in belowground microbial communities.

A plant’s inheritance : Soil legacy effects of crops and wild relatives in relation to plant functional traits

“…I showed that soil microbial community composition was not significantly affected by winter cover crop monocultures or mixtures previously occupying the soil and found only marginal effects of the preceding main crop. These result contrast with reported plant species specific influences in bulk soil microbial communities (Barberán et al 2015;Leff et al 2018), and the findings of chapter 5. This discrepancy may in part be attributed to the use of different methods to study microbial community composition as the biological legacy effects in chapter 3 were measured by PLFA, which quantifies microbial biomass by fatty acid markers (Zelles et al 1992;Zelles 1999;Frostegård, Tunlid & Bååth 2011), whereas in chapter 5 I made use of amplicon-sequencing.…”

“…However, it remains to be tested how results obtained in individual plants grown in controlled conditions translate into effects in plant communities, as results on plant community level are contradictory. In both tropical forests (Barberán et al 2015) and temperate grasslands (Leff et al 2018) soil microbial community composition could be related to plant community composition, but not to plant traits. Which raises the questions:…”

Range-expanding plant species and their belowground neighbours : digging into novel interactions

“…Secondly, the results of Chapter 6 showed that of all groups of rhizosphere organisms, only the community composition of fungi was more similar in closely than in distantly related plant species, which is in line with a previous study showing that plant phylogeny is a better predictor of community variation of fungi than of bacteria (Barberán et al 2015). The apparent phylogenetic conservation of specific root length may be the underlying mechanism of the relation between phylogenetic distance and fungal community dissimilarity.…”

Plant community and soil conditions individually affect soil microbial community assembly in experimental mesocosms

“…These experiments are certainly crucial to predict responses to expected global changes due to human activities. However, our understanding of assembly and structure of these communities is still incomplete enough to require additional basic experiments to supplement the extensive observational biogeography data (Barberán et al., 2015; Fierer & Jackson, 2006; Hogberg et al., 2007). The analyses here were limited by the environmental data available (most notably the absence of individual pool pH data); future experiments could build upon this work by including more physical measurements both at the beginning and during microbial assembly.…”