Coffee leaf litter decomposition: Short term home-field advantage in shaded coffee agro-ecosystems

Home-field advantage (HFA), when applied to decomposition, predicts that a substrate will decompose more quickly in a home environment compared to away environments, presumably due to specialized decomposer communities. Few empirical tests of HFA have been done in agricultural environments, where manipulated species composition and reduced biodiversity could increase the effects of HFA. We used both a six week tethered line experiment and a yearlong litterbag study as complementary methodologies to assess the decomposition of Coffea arabica and Coffea robusta leaf litter in three environments: (a) where C. arabica is grown, (b) where C. robusta is grown and (c) an adjacent forest, where coffee is not cultivated. Using the decay constant (k) and carbon to nitrogen ratios, we tested for evidence of accelerated decomposition in home environments, compared to congeneric-away and forested-away environments. We found evidence of HFA with the shorter-term tethered line experiment, where C. arabica decayed twice as quickly in its home environment and 50% faster in the congeneric away as it did in the forested-away environment. We found no evidence of HFA in the longer litterbag study, with no difference in decay based on species or environment. The carbon to nitrogen ratios for tethered line samples differed over time and by environments, driven by differences between the coffee environments and the forest. Our results provide some of the first evidence of HFA in an agricultural system, with effects even in a congeneric-away environment. While we found no evidence of HFA in the longer, yearlong litterbag study, a short term HFA could still provide an ecologically important pulse of nutrients if this pulse is synchronized with plant demand.

Automated summary

This study assessed the decomposition of coffee leaves in different environments and found that decomposition was faster in the home environment. This suggests the presence of home-field advantage (HFA) in agricultural systems, where substrate decomposition is more efficient in home environments.