Biodiversity-productivity relationship in urban vascular flora: a comparison between wild edible and non-edible plants

Abstract

Background: Wild edible plants are species that are not cultivated but can be consumed as food. These plants may exhibit the highest taxonomic and phylogenetic diversity within urban floras, since they have a longer history of use associated with humans than non-edible plants. Also, because biodiversity is strongly associated with biomass, edible plants plant might show higher productivity (biomass per site) than non-edible plants.
 Questions: Is taxonomic and phylogenetic diversity of wild edible plants higher than non-edibles within urban areas? Is the alpha-biodiversity of wild edible plants positively related to biomass productivity in urban areas?
 Study sites and years of study: Cities of the coastal Mediterranean-type ecosystem, central Chile, 2015 and 2016.
 Methods: We characterized the taxonomic and phylogenetic diversity of urban flora differentiating wild edible and non-edible plants. Then, we assessed whether alpha-diversity of assemblages is related to their biomass productivity.
 Results: Both taxonomic and phylogenetic diversity were higher for edibles than non-edible plants. For edible plants, biomass was positively related to species richness and negatively with the mean phylogenetic diversity (MPD, a measure of evolutionary relationship among plants within an assemblage).
 Conclusions: Species richness is a suitable proxy to estimate wild edible plant diversity and their biomass in cities surpassing other proxies, such as phylogenetic diversity. Negative effect of MPD on biomass suggests that only a subgroup of related plants, possibly highly adapted to urban conditions, contribute to edible plant production. The distinction between wild edible and non-edible plants offers a better understanding of the assembly rules and biodiversity-biomass relationship within urban floras.