Species matrix of Indonesian litter and soil Collembola with environmental factors

Collembola are among the most abundant and diverse microarthropods that
affect litter decomposition, control microbial functioning and support
invertebrate predators. Rainforest conversion and expansion of plantations
in tropical regions are associated with changes in microclimate and
biodiversity decline, but information on the impact of tropical land use
on Collembola communities and their seasonal fluctuations is very limited.
Here, we investigated seasonal fluctuations in density and community
composition of Collembola in rainforest, and in rubber and oil palm
plantations in Jambi province (Sumatra, Indonesia), a region with moderate
seasonality (wet and dry seasons) that experienced one of the strongest
deforestations globally during the last decades. Samples were taken at the
end of the wet season (March), the beginning of the dry season (June), the
end of the dry season (August) and the beginning of the wet season
(November). Collembola density in the litter was at a maximum at the
beginning of the wet season, whereas in soil it generally varied little.
Densities of euedaphic (soil-adapted) and epedaphic species (upper
litter-adapted) fluctuated less with season than hemiedaphic (lower
litter-adapted) and atmobiotic species (aboveground-adapted). Collembola
community composition changed with season in each of the land-use systems,
with the differences being more pronounced in litter than in soil.
Differences in community composition among all three land-use systems were
most pronounced at the beginning of the dry season. Water content, pH,
fungal and bacterial biomarkers, C/N ratio and root biomass were
identified as factors related to seasonal variations in species
composition of Collembola in different systems. Our results show that
Collembola density and community composition often fluctuate in a similar
way across land-use systems, indicating that they are driven by common
environmental factors, with water content, pH and food availability being
of prominent importance. Notably, differences in Collembola community
composition between rainforest and plantation systems were most pronounced
in the dry season (June, August), indicating that the conversion of
rainforest into plantation systems aggravates detrimental effects of low
moisture on soil animal communities. Fluctuations in Collembola
communities were generally stronger in litter than in soil, reflecting
that Collembola in litter are less buffered against climatic variations
than those in soil. Overall, the results document the sensitivity of
tropical soil animal communities to seasonal climatic variations, which
intensifies the effects of the conversion of rainforest into plantation
systems on soil biodiversity.