Effect of large herbivore decomposition on the succession of Mesic-grassland soil microbiomes

Abstract

Plant detritus is abundant in grassland but decomposes slowly and is relatively nutrient-poor, whereas animal carcasses are labile and nutrient-rich. Although nutrients from carcasses are highly sought-after, historically, they have been considered insignificant due to their brief decomposition period and minor contribution to the overall landscape nutrition. Recent studies have demonstrated that carcasses significantly alter long-term soil properties at an ecosystem scale. There is a paucity of empirical evidence of the temporal scale of functional and structural succession of the soil microbiome during and after carcass decomposition. Over a period of eighteen months, this study evaluated the functional and structural succession of the soil microbiomes beneath ten Connochaetes taurinus (wildebeest) carcasses. Functional succession was measured by the utilisation of 31 ecologically relevant carbon substrates using BiologTM EcoPlatesTM. Metagenomic analysis of 16S rRNA genes evaluated the bacterial community structural succession. Functional analysis results indicated that most soil microbial processes beneath the carcasses were accelerated for a limited period but resulted in an enduring increase in functional diversity. Substrate utilisation shifted successively and remained evident throughout the study period. Conversely, bacterial diversity was significantly reduced and dissimilar to control soil, although it recovered incrementally to the control soil levels within eighteen months. Biomarkers at different taxonomic levels were identified at various postmortem intervals up to eighteen months