Abstract
Tropical rainforests play important roles in carbon sequestration and are hot spots for biodiversity. Tropical forests are being replaced by rubber (Hevea brasiliensis) plantations, causing widespread concern of a crash in biodiversity. Such changes in aboveground vegetation might have stronger impacts on belowground biodiversity. We studied tropical rainforest fragments and derived rubber plantations at a network of sites in Xishuangbanna, China, hypothesizing a major decrease in diversity with conversion to plantations. We used metabarcoding of the 18S rRNA gene and recovered 2313 OTUs, with a total of 449 OTUs shared between the two land-use types. The most abundant phyla detected were Annelida (66.4% reads) followed by arthropods (15.5% reads) and nematodes (8.9% reads). Of these, only annelids were significantly more abundant in rubber plantation. Taken together, α- and β-diversity were significantly higher in forest than rubber plantation. Soil pH and spatial distance explained a significant portion of the variability in phylogenetic community structure for both land-use types. Community assembly was primarily influenced by stochastic processes. Overall it appears that forest replacement by rubber plantation results in an overall loss and extensive replacement of soil micro- and mesofaunal biodiversity, which should be regarded as an additional aspect of the impact of forest conversion.
Highlights
Tropical rainforests play important roles in biogeochemical cycling and climate regulation and act as reservoirs of global biodiversity by supporting around 50% of all described species[1,2,3]
It would be unrealistic to try to assign relative abundances of individuals to each taxonomic category since even closely related species of Metazoa from the same class or phylum can differ dramatically in size – and the samples pick up a great diversity of Metazoan taxa
The number of cells and the number of copies of phylogenetic markers per individual are influenced by their size and their biomass
Summary
Tropical rainforests play important roles in biogeochemical cycling and climate regulation and act as reservoirs of global biodiversity by supporting around 50% of all described species[1,2,3]. More than one million hectares of native forest have been converted to rubber plantation over the last few decades in the Mekong River Region alone[7] This has led to a substantial reduction in structural and functional biodiversity[5,8,9,10], a reduction in carbon sequestration[11,12], and an increase in habitat fragmentation[5,13] with noticeable alterations in the hydrological systems[14,15,16]. Www.nature.com/scientificreports stages of some metazoan species[23] These organisms have been often neglected from soil biodiversity surveys even though they are considered to play an important role in land ecosystem functioning. Xiao et al.[31] compared nematode diversity in natural forests and rubber plantations, finding that conversion was associated with a decrease in both α- and β- diversity
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