The role of edge contrast and forest structure in edge influence: vegetation and microclimate at edges in the Brazilian cerrado

Abstract

The effect of the adjacent non-forested environment on the forest near the edge, edge influence (EI), is an important impact in fragmented landscapes and is believed to vary with factors such as forest structure and edge contrast. In order to improve our understanding of the factors governing the variability in EI, we studied microclimate and vegetation at cerrado edges surrounded by variable land uses in southeastern Brazil, a system with both forest and savanna fragments. We determined the significance, magnitude and distance of EI on microclimate, vegetation structure and grass biomass which we measured along five transects perpendicular to fourteen edges in forest or savanna next to different land uses. We introduce a quantitative measure of edge contrast that considers land uses at different distances from the same edge (e.g., a firebreak between a forest edge and a plantation) and verified whether edge contrast is correlated with EI in this system. Notwithstanding the large variation in EI among variables and study sites, there were some similarities in the patterns of EI between forest and savanna edges. Edge contrast was successfully quantified by our measure but was only correlated with EI on moisture and grass biomass. Our results point to the high variability in EI within a region. Our quantitative measure of edge contrast may be useful in explaining variability in EI. However, much unexplained variation remains in the highly fragmented cerrado system which is affected by EI in both forest and savanna fragments.

Temporal persistence of edge effects on bryophytes within harvested forests

“…The observed temporal persistence in bryophyte community response to forest influence is consistent with patterns in beetle communities examined at the same sites (Fountain-Jones et al, 2015). Additionally, interior edge effects on bryophytes have also been shown to persist through time (Matlack, 1994;Dodonov et al, 2013). While this study showed forest influence on bryophytes, other studies have shown none (Hylander, 2009;Rudolphi and Gustafsson, 2011) although these studies originated from Boreal forest locations.…”

Analyzing the edge effects in a Brazilian seasonally dry tropical forest

“…It is therefore possible that "traditional" edge effects in biotic communities are directly related to the presence of a continuous canopy, and that vegetation forms adapted to seasonal environments are resistant at least in the stratum assessed. Nevertheless, Dodonov et al (2013) demonstrated difference in microclimatic edge of savanna formations and attributed to wind actions. According to Harper et al (2005) canopy cover, winds and a host of other variables, in fact determine the magnitude and distance of the edge effect, however, in seasonal environments the most of processes and responses remain unknown.…”

“…Noteworthy are Oliveira-Filho et al (1997, 2007 in semideciduous forest, Lima-Ribeiro (2008) and Dodonov et al (2013) in differents physiognomy of cerrado (tropical savanna), which found some effect, and Santos and Santos (2008) (in caatinga -tropical shrubland), Sampaio and Scariot (2011) and Oliveira et al (2013) in dry forest, who did not find.…”

Influence of Mature Overstory Trees on Adjacent 12-Year Regeneration and the Woody Understory: Aggregated Retention versus Intact Forest

“…This approach yields values that range between −1 and 1, with a value of 0 indicating no difference from conditions that might be expected following a conventional clearcut harvest [55]. We then tested the null hypothesis that aggregates and intact forest had no influence (MEI = 0) on surrounding regenerating areas using the randomized test of edge influence (RTEI) approach [56][57][58]. This entailed comparing mean observed MEI to 95% confidence intervals derived from a distribution of randomized MEI values for each response variable at each distance, individually (i.e., [56]).…”