Data from: The role of soil chemistry and plant neighbourhoods in structuring fungal communities in three Panamanian rainforests

Fungi play critical roles in ecosystem processes and interact with plant
communities in mutualistic, pathogenic, and commensal ways. Fungal
communities are thought to depend on both associated tree communities and
soil properties. However, the relative importance of the biotic and
abiotic drivers of soil fungal community structure and diversity in
lowland tropical forests remains poorly understood. We examined the
community structure of trees and fungi at different levels of phosphorus
(0·17–16·3 mg kg−1) in moist tropical forests in Panama. We predicted that
arbuscular mycorrhizal (AM) fungal composition would be more strongly
associated with soil properties than with local tree communities while the
composition of other fungal clades would be more strongly correlated with
local tree communities than soil properties. We also predicted that fungal
operational taxonomic unit (OTU) richness would be negatively correlated
with soil fertility and positively correlated with tree species diversity
within and among forests. We characterized soil chemistry, fine root
biomass, and sequenced the ITS1 barcode region to describe fungal
community composition from 70 soil cores across three 1-ha tropical
rainforest sites in Panama. The sites vary in soil chemistry, including P,
and in tree species community composition, but experience similar annual
rainfall. AM fungal community composition was partially correlated with
soil chemistry (r = 0·32, P ≤ 0·001), but not with local tree communities,
while non-AM fungal communities were nearly equally correlated with soil
chemistry (Partial Mantel test, r = 0·38, P ≤ 0·001) as with tree
communities (r = 0·36, P ≤ 0·001). Linear models showed that AM OTU
richness was not explained by any independent variable. For non-AM fungi,
phosphorus, pH, and soil moisture better predicted OTU richness across all
cores than other biotic and abiotic factors. Synthesis. Our results show
that AM fungal structure is driven primarily by soil chemistry. For non-AM
fungi, soil properties and the local tree community can play a joint role
in structuring communities. Furthermore, we found that more diverse local
tree communities did not harbour more fungal species. Our results suggest
that soil properties act as an environmental filter for both trees and
fungi, setting the stage for interactions between the two.