Richness and abundance of granivorous vertebrates determine acorn removal patterns in a human modified oak forest

"Most forests of the Earth have been affected by human activities and this can alter the plant-animal interactions on which depend the functional integrity of these ecosystems. In this study, we assessed the relationships between acorn removal rates and the richness and abundance of granivorous vertebrates along a forest-edge-clearing gradient. We also evaluated whether removal rates differed among oak species with different acorn size. To this purpose, a field experiment was performed including acorns of five oak species, which were exposed to seed consumers in the three different habitats (forest interior, man-made clearings and the edge between these habitats). The experimental units consisted in five paper trays containing 50 acorns of each oak species located at different distances from the edge towards the forest and the man-made clearing (0, 20 and 50 m). Experimental sites were equipped with phototraps to record the identity of the visiting granivorous vertebrates. Richness and abundance of granivores increased from the edge towards the forest interior, while the converse patterns were observed in the man-made clearing. For most oak species, acorn removal patterns was positively correlated with richness and abundances of granivores, though in all habitats small-sized acorns were removed much faster and in larger proportions than big-sized acorns. Although these results are specific for the study site, they suggest that man-made clearings reduce the richness and abundance of granivores, thus negatively affecting the secondary dispersion of zoochoric tree species towards open habitats. Further, it also seems that large-seeded oak species face greater dispersal limitations than small-seeded oaks, because of the lack of animals able to scatter them from the forest to the clearings.

Influence of human activities on some medium and large-sized mammals’ richness and abundance in the Lacandon Rainforest

"We evaluated the influence of six human activities (related variables) on the richness and abundance of large and medium-sized mammals in the southern portion of the Lacandon Rainforest, including protected and non-protected areas. The human activities measured have different influences on mammal richness and abundance. Our results show that some human activities (human density and anthropogenic land cover, and agriculture/cattle ranching) had no effect on large and medium-sized mammal populations, but community-based protection, such as medium levels of tourism and hunting, had a negative influence on richness and abundance. Those variables negatively influencing the mammal community were reported in one of the study sites. Data indicate both an opportunity for applied integral conservation actions that involve people and their activities, as well as an opportunity to support biodiversity conservation in agricultural landscapes by integrating human activities with protected areas and conservation.

The arabidopsis-trichoderma interaction reveals that the fungal growth medium is an important factor in plant growth induction

"Trichoderma spp colonizes the plant rhizosphere and provides pathogen resistance, abiotic stress tolerance, and enhance growth and development. We evaluated the Arabidopsis-Trichoderma interaction using a split system in which Trichoderma atroviride and Trichoderma virens were grown on PDA or MS medium. Arabidopsis growth was significantly increased at 3 and 5 days post-inoculation with both Trichoderma species, when the fungal strains were grown on PDA in split interaction. The analysis of DR5:uidA reporter line revealed a greater auxin accumulation in root tips when the fungi were grown on PDA in a split interaction. The root hair-defective phenotype of Arabidopsis rhd6 mutant was reverted with both Trichoderma species, even in split interactions. At 12 °C, Trichoderma species in split interactions were able to mitigate the effects of cold stress on the plant, and also Trichoderma induced the AtERD14 expression, a cold related gene. Volatile organic compounds analysis revealed that Trichoderma strains produce mainly sesquiterpenes, and that the type and abundance of these compounds was dependent on the fungal strain and the culture medium. Our results show that fungal nutrition is an important factor in plant growth in a split interaction.