Shade tree diversity, carbon sequestration, and epiphyte presence in coffee agroecosystems: A decade of smallholder management in San Ramón, Nicaragua

Abstract

Coffee smallholder management practices have received attention for their potential to conserve biodiversity and sequester carbon by maintaining structural complexity, high canopy diversity, and minimal external inputs. We conducted shade tree surveys on 95 1000m2 research plots over a 10-year period to identify patterns of shade tree density and diversity, epiphyte presence, and carbon stocks within smallholder shade coffee systems of northern Nicaragua. We also analyzed each of these parameters with respect to management by comparing collectively- and individually-managed farms. Our results indicate that the overall shade tree density has decreased over time (F=42.597, p<0.001), but that diversity remained constant. Carbon stocks in coffee systems also showed a decreasing trend over time (F=2.981, p=0.056), most likely due to the decreasing tree densities. Epiphytic plant presence increased over time despite decreased host tree densities, suggesting either a change in management or improved habitat conditions for epiphytes. Research plots on individually-managed coffee farms generally had higher shade tree densities than those on collectively managed farms (t=2.141, p=0.037), but we found no differences in shade tree species richness or carbon stocks (t=0.573, p=0.568). We conclude that smallholder coffee farmers continue to conserve both shade tree diversity and epiphyte communities.