Mon, Aug 02, 2021:On Demand
Background/Question/Methods . The Conspecific Negative Density Dependence hypothesis (CNDD) as a mechanism to explain plant coexistence of the extraordinary biodiversity of ecosystems, such as the Amazonian tropical rainforest, is still not clear. It is thought that this process may promote population control preventing species from becoming locally abundant (e.g. aggregated or even monodominant) and allowing them to thrive. However, there are some tree species that are adapted to live in clusters. How can this happen? One potential strategy of plants to defy the negative effects of living in aggregation would be the efficient use of nutrients mainly coming from their own litter resources that are potentially invested in by themselves for both, growth and defense. If so, one would expect (i) decomposer communities within the sites of aggregated conspecifics to be quantitatively and qualitatively different from what is found outside these microhabitats, and (ii) the leaf-litter decomposition to be higher where individuals are more densely distributed. It was hypothesized that (1) invertebrate communities in microhabitats of aggregated plant species are significantly different in terms of abundance, richness and functionality, compared to the sites where aggregated plants are not present. And (2) leaf-litter decomposes significantly faster in areas of conspecific density. By using two complementary sampling methodologies, Winkler and Pitfall traps, this study provides a description of (i) soil detritivore diversity of six common tree species in Yasuní National Park, Ecuador, in areas of significant aggregation (home; IN) vs areas of total absence (OUT). (ii) By using mesh bags to follow leaf-litter decomposition, it quantifies the percentage of mass loss of 12 leaf-litter species: the six aggregated, and other six with non-aggregation patterns, inside and outside home for the two groups.
Results/Conclusions . It was indeed found that soil invertebrates are clustered in small-scale patches and specific to the areas of plants aggregation. However, decomposition showed to be faster for non-aggregated plants, both inside and outside their highest density distribution zones. These results suggest that (1) plants may create habitats that promote the association of particular soil invertebrate species to efficiently exploit local nutrients, and (2) non-aggregated plants are adapted to be more effective at consuming nutrients from different sources. (3) Finally, the study shows that the 'home field advantage hypothesis' may not apply at the microhabitat level in hyperdiverse tropical forests.
Results/Conclusions . It was indeed found that soil invertebrates are clustered in small-scale patches and specific to the areas of plants aggregation. However, decomposition showed to be faster for non-aggregated plants, both inside and outside their highest density distribution zones. These results suggest that (1) plants may create habitats that promote the association of particular soil invertebrate species to efficiently exploit local nutrients, and (2) non-aggregated plants are adapted to be more effective at consuming nutrients from different sources. (3) Finally, the study shows that the 'home field advantage hypothesis' may not apply at the microhabitat level in hyperdiverse tropical forests.