Landscape Attributes Drive Complex Spatial Microclimate Configuration of Brazilian Atlantic Forest Fragments

Abstract

Habitat fragmentation imposes profound impacts on the tropical forest microclimate, but the microclimatic configuration of isolated forest patches and its implications for biodiversity persistence and habitat management are not clear. In this study we assessed a set of 10 aged (> 80 years) fragments (3.0 -3,500 ha in size) of the Atlantic forest to examine to what extent fragment microclimatic attributes are correlated with distance to the nearest edge as frequently proposed in the literature. We used 129 sampling points and took a total of 516 measures of air temperature and humidity, vapor pressure deficit and light incidence to characterize the microclimate of forest fragments in terms of their relative deviation from the surrounding matrix. Fragments as a whole presented strong internal variation and strongly differed from the microclimate exhibited by the open matrix of sugar-cane fields. Distance to nearest edge, percentage of forest cover around the measurement point, percentage of edge-affected area, and geographical orientation of the nearest edge all proved to have minor effects on the microclimate of forest fragments. Conversely, we identified percentage of forest cover and fragment area as the most significant explanatory variables driving their microclimatic configuration: as forest cover increases at landscape scale, forest microclimate deviates less from the open matrix (a forest-mediated matrix buffering). Our results suggest that microclimatic conditions are spatially complex, as they do not correlate with the distance to the nearest forest edges; rather, they are driven by a forest-mediated buffering of the surrounding matrix that minimizes heat and humidity exchanges between forest and non-forest habitats, thus shaping the microclimatic signature of isolated forest fragments. Keywords: edge effects; habitat fragmentation; hyper-fragmented landscapes; microclimate; tropical forest. ResumenLa fragmentación del hábitat tiene importantes impactos en el microclima de los bosques tropicales, pero los determinantes del microclima en fragmentos aislados y sus efectos sobre la biodiversidad y el manejo de estos ecosistemas aún son mal comprendidos. En este estudio, analizamos un total de 10 fragmentos de bosque (3 -3,500 ha) aislados por más de 80 años para entender como los parámetros microclimáticos responden a características del paisaje, de los fragmentos, a la distancia al borde más próximo. Para ello, en un total de 129 puntos tomamos 516 mediciones de temperatura del aire, humedad relativa del aire, déficit de presión de vapor e incidencia de luz difusa para caracterizar el microclima de estos fragmentos en relación a los valores de la matriz adyacente. Como esperado, los fragmentos presentaron fuerte variación interna y diferirán largamente del microclima encontrado en la matriz no-forestal. La distancia al borde y otras tres variables no presentaron efectos muy significativos sobre el microclima de los fragmentos como un todo. Por otro lado, identificamos que el porcentaje de cobertura...

Functional diversity and management mediate aboveground carbon stocks in small forest fragments

“…Habitat connectivity can positively affect plant species richness, for example by increasing seed dispersal, facilitating pollen movement, and altering foraging (Tewksbury et al 2002), even in areas with seemingly small distances of isolation between patches. Damschen et al (2006) found a net positive effect on native plant species richness in patches connected by corridors, compared to patches isolated by 150 m. Additionally, surrounding forests may have the potential to buffer existing forest fragments from microclimatic edge effects; in tropical forests, landscape level influences such as increasing forest cover and structural connectivity influenced microclimatic differences between forest fragments and the surrounding matrix, with air temperature and moisture in larger and more connected fragments deviating less from the surrounding matrix (Pinto et al 2010). However, the majority of forest fragmentation studies focus primarily on summary metrics such as species richness and composition (Estades and Temple 1999, Honnay et al 1999, Petit et al 2004, Uezu et al 2005, Damschen et al 2006, Echeverría et al 2007, and dispersal of organisms (Tewksbury et al 2002, McEuen and Curran 2004, Kolb and Diekmann 2005, Pardini et al 2005, and rarely make the link to ecosystem functions or services (but see Billings and Gaydess 2008).…”

Peripheral Isolates as Sources of Adaptive Diversity under Climate Change

“…Factors such as latitude, vegetation cover, elevation, and distance from the coastline all create substantial spatial variation in climate (e.g., Shoo et al, 2010Shoo et al, , 2011. Indeed, microclimate may differ over even very small landscape scales (e.g., Pinto et al, 2010). For all of these reasons, isolates at the geographic edge of a species' range will likely experience a different climate (both in mean and extreme values) from the climate at the center of the species' range (Lesica and Allendorf, 1995).…”

Tropical forest degradation and recovery in fragmented landscapes — Simulating changes in tree community, forest hydrology and carbon balance

“…It 1 is important to note that due to the favorable fragment shape and size, several fragment plots were located inside the >200 m 2 range. However, due to the complexities of edge penetration by microclimatic effects (Pinto et al, 2010) and isolation, these 3 samples were still statistically considered as fragments, and not core areas (Melo et al, 2006;Santos et al, 2008;Tabarelli 4 and Lopes, 2008). To illustrate this, we separated the small fragment plots into edges and core, with the same criteria 5 as used for the large fragment Coimbra (200 m edge) and compared the biomass values (Fig.…”

“…This is allowed for a more realistic reproduction of the temporal behavior 14 of the model in relation to stem number and biomass changes. Using this core of large forest fragment parameterization, we 15 modified the mortality and establishment parameters and executed simulations with FORMIND, seeking to reproduce edge 16 of large fragment and small fragment stem number and biomass field conditions. These two parameters are considered To simulate changes in forest hydrology, we used FORMIND's climate module, and parameterized it with daily precipitation and potential evapotranspiration from historic averages measured around 60 km from the Serra Grande landscape, Evapotranspiration and total runoff for each patch are calculated based primarily on daily precipitation, potential 35 evapotranspiration, forest structure and soil characteristics.…”

“…13 14 In order to reproduce the transitions with the FORMIND model, we changed the seedling ingrowth and mortality 15 parameters for each habitat. For the degradation transitions (core of large fragment to edge of large fragment, and core of large 16 fragment to small fragment) we initialized the model with core of large fragment field samples, but executed it with edge of 17 large fragment or small fragment parameters, simulating the sudden change in core conditions during a degradation process 18 caused by edge effects.…”