Wild native trees in tropical homegardens of Southeast Mexico: Fostered by fragmentation, mediated by management

Tropical homegardens (THGs) are a model system for rural development that may reconcile food production with social resilience and biodiversity conservation, particularly in rapidly changing landscapes. This study quantified the sink function of THGs for wild native trees in relation to tree cover fragmentation, garden management and household socio-economics. Abundance, richness and diversity of naturally established spared native trees were recorded for 59 rural THGs in Southeast Mexico, along a gradient of tree cover fragmentation. The majority of native species and individuals encountered in THGs had arrived naturally. Contrary to previous work, both the abundance and diversity of spared native trees increased with tree cover fragmentation. However, this sink function was strongly mediated by the type of garden management: lush, multi-layered gardens and gardens with few exotics and low labour input had more spared native trees of more species, while simple-structured gardens and gardens with high labour input and many exotic fruits had only few. Overall, the results indicate that tree cover fragmentation determines which species come in, and management determines how many of each stay. Our results clearly demonstrate that THGs are crucial sinks for wild native trees in deforested fragmented landscapes. THGs are ubiquitous, and could also be key sources for reforestation; here we coin homegarden-based natural regeneration as a new concept. Since garden management has a clear impact, further research is needed as to how socio-economic, cultural and ecological functions of THGs can be optimised in different landscape contexts.