Differential effects of anthropogenic edges and gaps on the reproduction of a forest-dwelling plant: The role of plant reproductive effort and nectar robbing by bumblebees

Phenology of Araucaria Forest fern communities: comparison of the influence of natural edge, artificial edge, and forest interior

The edge effect, triggered by habitat fragmentation, alters forest microclimates and influences the life cycle of plants. Phenology may indicate the first changes in phenological patterns in response to the effects of climate change. Climate regulates the phenology of ferns and climatic triggers influence plants in tropical and subtropical regions differently. This study analyzed and compared the phenology of fern communities of three sub-areas - natural edge, artificial edge, and forest interior - of a fragment of Araucaria Forest in the Floresta Nacional de São Francisco de Paula, Rio Grande do Sul, Brazil, and its relationship with meteorological, astronomical, and edaphic variables. Abiotic and edaphic data were monitored concomitantly with phenological data (leaf renewal and senescence and sporangia formation) in each sub-area over a biennium. Temperature, air humidity, and soil moisture, which undergo changes with the edge effect, influenced edge plants. Leaf renewal was the main phenophase showing strong indication of changes in vegetative patterns in natural and artificial edge communities. Among the communities, that of the artificial edge signaled phenological changes that could compromise the development of ferns if effects intensify over time. In this respect, the phenology of artificial edge ferns differed from that of plants growing in originally natural formations (natural edge and forest interior), showing that exogenous transformations represent a new environmental situation for ferns to develop.

Ants on Clerodendrum infortunatum: Disentangling Effects of Larceny and Herbivory

Nectar larcenists extract nectar from flowers without pollinating them. A reasonable expectation is that any form of nectar larceny should have a detrimental effect on the plant's reproductive success. However, studies reveal an entire range of effects, from highly negative to highly positive. This variation in effect may be partly explained by additional, unmeasured, effects of nectar larcenists on plants. In a study system where two ant species Tapinoma melanocephalum (Fabr.) (Hymenoptera: Formicidae) and Trichomyrmex destructor (Jerd.) (Hymenoptera: Formicidae) act as nectar larcenists, we examined the effect of larceny on the female reproductive success of Clerodendrum infortunatum Gaertn. (Lamiales: Lamiaceae) in rain forest fragments of the Western Ghats, India. This was done through a combination of field observations and a series of field experiments looking at the effects of excluding ants from inflorescences. We found that T. destructor reduces fruit set considerably. Rather than this being a consequence of nectar larceny, however, our experiments show that the negative effect arises instead from the herbivorous behavior of the ant. At a population level, both ant species prefer edges over interiors of forest patches, spatially concentrating the interaction zone to forest edges. Simultaneously considering multiple ecological interactions and disentangling their relative contributions might explain the large variation across species in the observed effect of larceny. The overall population effect of nectar larceny and herbivory is likely to depend on the spatial structuring of plants and ants.

Internal habitat quality determines the effects of fragmentation on austral forest climbing and epiphytic angiosperms

Habitat fragmentation has become one of the major threats to biodiversity worldwide, particularly in the case of forests, which have suffered enormous losses during the past decades. We analyzed how changes in patch configuration and habitat quality derived from the fragmentation of austral temperate rainforests affect the distribution of six species of forest-dwelling climbing and epiphytic angiosperms. Epiphyte and vine abundance is primarily affected by the internal characteristics of patches (such as tree size, the presence of logging gaps or the proximity to patch edges) rather than patch and landscape features (such as patch size, shape or connectivity). These responses were intimately related to species-specific characteristics such as drought- or shade-tolerance. Our study therefore suggests that plant responses to fragmentation are contingent on both the species' ecology and the specific pathways through which the study area is being fragmented, (i.e. extensive logging that shaped the boundaries of current forest patches plus recent, unregulated logging that creates gaps within patches). Management practices in fragmented landscapes should therefore consider habitat quality within patches together with other spatial attributes at landscape or patch scales.