Recent advances in metabolomics enhances our understanding of the ecological impacts stemming from plant chemical diversity. However, few studies have examined how phytochemical diversity affects herbivore damage at the community scale in tropical tree communities.
In a study published in Ecology Letters, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) investigated the relationship between community phytochemical diversity and herbivore-induced leaf damage, by integrating untargeted metabolomics, a plastome-based phylogeny, and a long-term tropical forest monitoring plot of 358 species.
Using untargeted metabolomics, the researchers evaluated secondary metabolites and measured herbivory for 358 plant species in a 20-ha forest dynamics plot in tropical rainforest at Xishuangbanna in SW China.
The researchers demarcated the plot into 20×20 m quadrats (500 in total) and used species-level metabolome and herbivory observations to calculate phytochemical diversity and dissimilarity and herbivory in local tree communities and examined their relationships with light environment and soil nutrients at the spatial scale.
They reported no phylogenetic signal in most compound classes, indicating rapid diversification in tree metabolomes. They found that locally co-occurring species were more chemically dissimilar than random and that local chemical dispersion and metabolite diversity were associated with lower herbivory, especially that of specialist insect herbivores.
The findings revealed a decline in overall herbivory as metabolite diversity increases within the community. Plant neighbourhoods with diverse secondary metabolites reduced the rate of damage by herbivores, especially specialist herbivores with limited host ranges and the potential for density-dependent impacts on plants.
The role of specialist herbivores in promoting local neighbourhoods of chemically dissimilar and diverse trees suggested that chemically mediated plant–herbivore interactions represented a key component of the niche with the potential to contribute to the maintenance of tree species diversity in tropical forests.
"Our results highlight the role of secondary metabolites in mediating plant–herbivore interactions and their potential to facilitate niche differentiation in a manner that contributes to species coexistence," said YANG Jie of XTBG.