Edge effects enhance selfing and seed harvesting efforts in the insect-pollinated Neotropical tree Copaifera langsdorffii (Fabaceae)

Small Landscape Elements Double Connectivity in Highly Fragmented Areas of the Brazilian Atlantic Forest

The Atlantic Forest in Brazil is a biodiversity hotspot, yet its diverse ecosystems and species are becoming increasingly threatened by habitat loss and extreme habitat fragmentation. Most habitat patches of Atlantic Forest are dispersed across agricultural landscapes (e.g., grazing and cropping) in relatively small and isolated fragments (80% < 50 ha). Forest fragments < 1 ha, scattered trees in pastures, tree lines on trenches and fences, and remnant riparian forest, collectively called here Small Landscape Elements (SLEs), are very common in this context. While these SLEs make up much of the Atlantic Forests footprint, very little is known about their role or impact on the persistence and conservation of species. In this study, we investigate the role of SLEs on landscape configuration, particularly their contribution toward landscape connectivity of individual species and the genetic flow of species between larger forest fragments. We randomly selected 20 buffers of 707 hectares within a 411,670 hectare area of the Atlantic Forest that was completely covered by forest in the past located in the south of Minas Gerais State, Brazil. The forest cover randomly varied between these buffers. We used graph theory to measure landscape connectivity as the probability of connectivity for different disperser movement types between landscape knots (habitat patches). We used three estimated dispersal distances in the models: pollen disperser insect (50 m), low-mobility seed disperser bird (100 m) and high-mobility seed disperser bird (760 m). The SLEs together increased the probability of connection by roughly 50%, for all model dispersers, if compared to a theoretical baseline landscape containing no SLEs. Of all SLEs, riparian forests contribute the most toward enhancing landscape connectivity. In these highly fragmented landscapes, such as the Atlantic Forest (>70%), the position of SLEs within the landscapes was more important than their respective areas for connectivity. Although the landscapes were deeply fragmented, we showed that the presence of SLEs can increase connectivity and reduce further biodiversity loss in the Atlantic Forest.

Reproductive ecology of Ocotea catharinensis, an endangered tree species

Ocotea catharinensis (Lauraceae) is an endangered tree species from the Brazilian Atlantic Rainforest. Currently, little is known about the reproductive ecology of this species. Aiming to propose conservation measures, we described aspects related to phenology, floral biology, pollination, seed dispersal and mating system of O. catharinensis. We conducted phenological observations in 62 individuals for 2 years. In one reproductive event, we evaluated nectar production, stigmatic receptivity and pollen viability. Floral visitors were observed, identified and classified on a scale of pollination effectiveness. Seed dispersers were observed and identified using camera traps. Finally, the mating system was evaluated through pollen/ovule ratios, experimental pollination treatments and genetic analysis with molecular markers. Ocotea catharinensis presented a supra-annual fruiting pattern with a substantial reduction of reproducing individuals from bud phase to ripe fruit phase. Several mechanisms prompting cross-fertilisation were identified, such as attractive, herkogamic and protogynic flowers. The main floral visitors and pollinators were from the Diptera order, and all seed dispersers were birds. The species presented a predominantly outcrossed mixed mating system with significant selfing rate (17.3%). Although based on restricted evidence, we hypothesised that selfing is an escape mechanism for situations unfavourable to cross-fertilisation. Specifically, for the studied population selfing is a response to reduced population size, which is caused by the non-reproduction of all potentially reproductive individuals and by past exploitation events. Therefore, conservation efforts should be able to enhance population sizes, as well as prevent overexploitation.