Dung beetle activity had no positive effect on nutrient concentration or performance of established rainforest seedlings

Abstract

AbstractDung beetle activity causes many changes in the soil when they remove feces from the surface. In temperate grasslands and in greenhouse experiments, these changes have been found to positively affect established plants, but information about these effects under natural conditions in tropical forests is practically nonexistent. In a tropical rainforest (Los Tuxtlas, Mexico), we carried out field experiments with seedlings of six tree species (Brosimum alicastrum, Calophyllum brasiliense, Cymbopetalum baillonii, Diospyros digyna, Omphalea oleifera, and Poulsenia armata), to assess whether feces burial by dung beetles had any positive effect on them. We estimated foliar nitrogen and phosphorus, seedling survival, growth and resource allocation, under three treatment levels: (a) feces added and beetles active, (b) feces added and beetles excluded, and (c) no feces added (and consequently no beetles active). We analyzed data at two levels: community (all plant species together) and individual species. Dung beetle activity did not increase the concentration of foliar nutrients or seedling performance (survival, growth); in one species, it modified resource allocation. At the community level and for two species, dung beetle activity decreased the probability of seedlings growing in height. Our study provides evidence on how extrapolating the effects of dung beetle activity from other study systems into tropical forests can be problematic. More studies will be needed before we can have a clearer idea of the effects that feces burial by dung beetles have on established plants in tropical forests.Abstract in Spanish is available with online material.