Land use history can have long-lasting impacts on biotic communities and the signal of past human land use can sometimes be detected centuries later. Often, we document changes associated with this past land use on the vegetative community. But, we also know that these implications can be long-lasting in other, more cryptic, biotic communities such as ants and earthworms. Importantly, these groups have the potential to further impact important ecosystem functions such as litter turnover and seed dispersal for earthworms and ants, respectively. As such, shifts in these groups can have outsized impacts that can cascade through the system. Here, we take advantage of a forest with a variety of past land use histories to explore variation in earthworm invasions as a function of past land use. We then explore relationships between native ants and both earthworm invasion and past land use. Finally, we explore patterns of seed dispersal across the landscape consisting of a mosaic of past agricultural land use.
Results/Conclusions
We find that past agricultural land use is associated with higher levels of earthworm invasion. High earthworm abundance, in turn, restructured ant community composition. However, neither land use history, nor earthworm abundance depressed abundances of the most prolific seed disperser in the system: Aphaenogaster picea. Despite this, overall levels of ant-mediated seed dispersal were lower on lands recovering from past agricultural land use. There were also fewer myrmecochorous plant species in forested patches recovering from past agricultural land use (though there may be many, potentially interacting, reasons for this). Ultimately, we find that past land use drives cryptic forms of biodiversity across multiple biotic systems, altering forest function in ways that are important for relationships between ants and plants.