Spatio-temporal distribution and contributing factors of tegumentary and visceral leishmaniasis: A comparative study in Bahia, Brazil.

Tegumentary (TL) and visceral (VL) leishmaniasis are neglected zoonotic diseases in Brazil, caused by different parasites and transmitted by various vector species. This study investigated and compared spatio-temporal patterns of TL and VL from 2007 to 2020 in the state of Bahia, Brazil, and their correlations with extrinsic factors. The results showed that the total number of cases of both TL and VL were decreasing. The number of municipalities with reported cases reduced for TL over time but remained almost unchanged for VL. There were few municipalities with reported both diseases. Statistical analysis showed that local TL incidence was associated positively with natural forest. Local VL incidence was associated positively with Cerrado (Brazilian savannah) vegetation. This study identified different patterns of occurrence of VL and TL and the risk areas that could be prioritized for epidemiological surveillance.

Modeling landslide activity and sediment connectivity after eruptions: Insights from the Blanco River (Chile).

Volcanic eruptions can disrupt entire river basins by affecting the hydro-geomorphic characteristics of channel networks and hillslopes. Reports suggest a pulsed and delayed increase in landslide activity following the eruptions, which, depending on the degree of linkage between hillslopes and channels, i.e. sediment connectivity, can represent a massive source of sediment input for the fluvial system. Therefore, predicting landslide occurrence and sediment connectivity is fundamental for management risk strategies, especially in such dynamic and complex environments. The aim of this work is to develop and offer a more reliable approach to map the areas susceptible to landslides and connected to the active channel in a catchment impacted by volcanic eruption. The analyses were carried out in the Blanco River catchment in southern Chile, affected by the Chaitén eruption (2008-09). A combined approach is presented, based on landslide susceptibility models, carried out multi-temporally (from 2010 to 2019), and a threshold-based sediment connectivity map. The results showed that the highest landslide occurrence was reported 4 years after the eruption, whereas the faster increase in the overall area affected was observed only after 7 years. Landslide susceptibility models showed high accuracy when applied in the same year, but were less accurate in predicting future occurrences. This result is ascribed to the dynamic conditions of the vegetation, regenerating quickly after the mass movements. Nevertheless, considering the potential sources of error, the combined landslide susceptibility-connectivity map for the year 2019 well-identified relevant areas for catchment management. The largest part of the catchment was found non-susceptible and disconnected, while areas classified as susceptible and connected represent only 3.1 %. The application of this novel approach allowed to unravel the geomorphic trajectory of the study area and, more importantly, can represent a benchmark for future applications in other catchments affected by large disturbances.

Protection from overheating of simulated Sceloporus horridus lizards in a biosphere reserve of seasonally dry tropical forest in central Mexico.

In seasonally dry ecosystems, loss of vegetation cover leads to warmer microclimates that can increase lizards' body temperatures to the point of threatening their performance. Preserving vegetation by establishing protected areas may mitigate these effects. We used remote sensing to test these ideas in the Sierra de Huautla Biosphere Reserve (REBIOSH) and surrounding areas. First, we determined whether vegetation cover was higher in the REBIOSH compared to adjacent unprotected areas to the north (NAA) and south (SAA). Then, we used a mechanistic niche model to test whether simulated Sceloporus horridus lizards in the REBIOSH experienced a cooler microclimate, higher thermal safety margin, longer foraging duration, and lower basal metabolic rate compared to adjacent unprotected areas. We compared these variables between 1999, when the reserve was declared, and 2020. We found that vegetation cover increased from 1999 to 2020 in all three areas; it was higher in the REBIOSH than in the more anthropized NAA, and was intermediate in the less anthropized SAA in both years. The microclimate temperature decreased from 1999 to 2020 and was lower in the REBIOSH and SAA than in the NAA. Thermal safety margin increased from 1999 to 2020; it was higher in the REBIOSH than in the NAA and intermediate in the SAA. Foraging duration increased from 1999 to 2020 and was similar among the three polygons. Basal metabolic rate decreased from 1999 to 2020 and was higher in the NAA than in the REBIOSH and SAA. Our results suggest that the REBIOSH provides cooler microclimates that increase the thermal safety margin and lower the metabolic rate of this generalist lizard compared to the NAA, and that the REBIOSH could contribute to increased vegetation cover in its surroundings. Besides, protecting original vegetation cover is an important part of climate change mitigation strategies more generally.

Ephemeral forest regeneration limits carbon sequestration potential in the Brazilian Atlantic Forest.

Although deforestation remains widespread in the tropics, many places are now experiencing significant forest recovery (i.e., forest transition), offering an optimistic outlook for natural ecosystem recovery and carbon sequestration. Naturally regenerated forests, however, may not persist, so a more nuanced understanding of the drivers of forest change in the tropics is critical to ensure the success of reforestation efforts and carbon sequestration targets. Here we use 35 years of detailed land cover data to investigate forest trajectories in 3014 municipalities in the Brazilian Atlantic Forest (AF), a biodiversity and conservation hotspot. Although deforestation was evident in some regions, deforestation reversals, the typical forest transition trajectory, were the prevalent trend in the AF, accounting for 38% of municipalities. However, simultaneous reforestation reversals in the region (13% of municipalities) suggest that these short-term increases in native forest cover do not necessarily translate into persistent trends. In the absence of reversals in reforestation, forests in the region could have sequestered 1.75 Pg C, over three times the actual estimated carbon sequestration (0.52 Pg C). We also showed that failure to distinguish native and planted forests would have masked native forest cover loss in the region and overestimated reforestation by 3.2 Mha and carbon sequestration from natural forest regeneration by 0.37 Pg C. Deforestation reversals were prevalent in urbanized municipalities with limited forest cover and high agricultural productivity, highlighting the importance of favorable socioeconomic conditions in promoting reforestation. Successful forest restoration efforts will require development and enforcement of environmental policies that promote forest regeneration and ensure the permanence of regrowing forests. This is crucial not only for the fate and conservation of the AF, but also for other tropical nations to achieve their restoration and carbon sequestration commitments.

Influence of landscape composition and configuration on the richness and abundance of potential sylvatic yellow fever vectors in a remnant of Atlantic Forest in the city of São Paulo, Brazil.

The landscape's structure can play a relevant role in epidemic patterns of arboviruses, influencing factors such as abundance, movement, and dispersal ability in arthropod vectors and vertebrate hosts, besides promoting alterations in the rate of potential infectious contacts between these organisms. In the Americas, yellow fever (YF) exhibits only the sylvatic cycle, in which the virus circulates in sylvatic areas among non-human primates, being transmitted by mosquitoes of the Haemagogus and Sabethes genera. In this study, we investigate some aspects of the landscape in relation to diversity and abundance of culicid species associated with YF transmission. Studies were performed in the Cantareira State Park, a remnant of the Atlantic Forest located in Greater Metropolitan São Paulo, Brazil, where the YF virus circulated recently with dozens of deaths in howler monkeys (Alouatta guariba), in addition to reported human cases. Mosquito collections were carried out monthly from February 2015 to April 2017. Mosquitoes were collected from three sites using battery-powered aspirator (12-volt battery), CDC, and Shannon traps for adults, and suction samplers and entomological spoons in breeding sites to collect immature forms. 703 mosquitoes belonging to 12 species of the Aedini and Sabethini tribes were collected. Aedes scapularis and Psorophora ferox exhibited higher abundance, while Haemagogus leucocelaenus, the main vector of YF in São Paulo state, showed lower abundance in all sampled areas. The site with longer edge between forest area and anthropic area presented more richness and abundance of YF vector species, while the site with larger forest cover area and shorter edges between forest and anthropic areas exhibited an inverse pattern. Statistically significant differences were observed between the composition of potential YF vector species among the investigated sites. Although Hg. leucocelaenus occurred in all sampled sites, the different patterns of distribution and abundance of other mosquitoes such as Aedes scapularis and Psorophora ferox suggest that these species may be involved in the transmission of sylvatic YF in the study area.

Mediation of area and edge effects in forest fragments by adjacent land use.

Habitat loss, fragmentation, and degradation have pervasive detrimental effects on tropical forest biodiversity, but the role of the surrounding land use (i.e., matrix) in determining the severity of these impacts remains poorly understood. We surveyed bird species across an interior-edge-matrix gradient to assess the effects of matrix type on biodiversity at 49 different sites with varying levels of landscape fragmentation in the Brazilian Atlantic Forest-a highly threatened biodiversity hotspot. Both area and edge effects were more pronounced in forest patches bordering pasture matrix, whereas patches bordering Eucalyptus plantation maintained compositionally similar bird communities between the edge and the interior and exhibited reduced effects of patch size. These results suggest the type of matrix in which forest fragments are situated can explain a substantial amount of the widely reported variability in biodiversity responses to forest loss and fragmentation.

Mediación de los Efectos de Área y de Borde sobre los Fragmentos de Bosque Causados por el Uso de Suelo Adyacente Resumen La pérdida del hábitat, la fragmentación y la degradación tienen efectos nocivos generalizados sobre la biodiversidad de los bosques tropicales. A pesar de esto, el papel del uso de suelo de los terrenos adyacentes (es decir, la matriz) en la determinación de la gravedad de estos impactos todavía está poco entendido. Censamos las especies de aves a lo largo de un gradiente de borde interno de matriz para evaluar los efectos del tipo de matriz sobre la biodiversidad en al menos 49 sitios con diferentes niveles de fragmentación del paisaje en el Bosque Atlántico Brasileño - un punto caliente de biodiversidad que se encuentra severamente amenazado. Tanto los efectos de área como los de borde estuvieron más pronunciados en los fragmentos de bosque que limitan con la matriz de pasturas, mientras que los fragmentos que limitan con plantaciones de Eucalyptus mantuvieron comunidades de aves similares en composición con aquellas entre el borde y el interior y mostraron efectos reducidos del tamaño de fragmento. Estos resultados sugieren que el tipo de matriz en el cual están situados los fragmentos de bosque puede explicar una cantidad sustancial de la ampliamente reportada variabilidad de respuestas a la pérdida del bosque y a la fragmentación.

The Response of Neotropical Dragonflies (Insecta: Odonata) to Local and Regional Abiotic Factors in Small Streams of the Amazon.

Since the relative role of local and regional abiotic factors on the Odonata diversity in rainforest streams is still poorly understood, we evaluated the effects of these factors on adult Odonata (Insecta) from preserved and altered streams in the Amazonian region. Adult Odonata were sampled in 98 streams in the Eastern Amazon, Pará, Brazil. Six variables were used to measure local environmental factors: habitat integrity index; mean canopy over the channel; and four physical and chemical descriptors of the water. To measure regional environmental factors, six variables were also used: altitude gradient, three bioclimatic variables and two percentage forest variables. In partial redundancy analysis, both abiotic factors (local and regional) were important to explain the variation in the Odonata community. The Odonata community can be influenced by regional and local factors. The relationship between Odonata and the local (e.g., integrity, canopy cover, and physical and chemical descriptors of the water) and regional (e.g., bioclimatic and forest cover variables) environmental variables recorded in this study has important implications for the use of these organisms to monitor small streams of the Eastern Amazon. The scale at which habitat is measured is an important issue in community structuring studies considering the rapid environmental changes. It is of great importance to consider the different scales in studies assessing community structure, once an adequate habitat must meet the ecological needs of all stages of the life of the Odonata.

Can forests buffer negative impacts of land-use and climate changes on water ecosystem services? The case of a Brazilian megalopolis.

While the role of land-use conversion on water quality is reasonably understood, its role on water quantity is controversial. Climate change is also expected to impact water availability. Here we explore the interplay of hydrology, land-use change and climate change in one of the most populous urban areas in the world. We examined the potential of forests to buffer the negative impacts of land-use and climate changes on water-related ecosystem services in Tietê Basin, Brazil, which supplies water to the São Paulo megalopolis. We modelled six hydrological parameters using the WaterWorld Policy Support System, simulating the current baseline and six future scenarios (with different land-use and climate changes). Our results corroborate the general trend that increased forest cover improves water quality. Our modelling also predicts that increased forest cover increases water quantity in the southern part of the basin. The effects of climate change are observed mainly in urban areas, with a reduction in water quality. Because urban areas are not eligible for reforestation, they cannot benefit from its buffering effect on climate change. The increase in water availability is the greatest benefit of reforestation as a strategy to improve water-related ecosystem services in the region. Reforestation, however, will not suffice to restore all hydrological parameters in the basin, and additional sustainable agricultural practices are needed to mitigate impacts on water quality.

Landscape, Climate and Hantavirus Cardiopulmonary Syndrome Outbreaks.

We performed a literature review in order to improve our understanding of how landscape and climate drivers affect HCPS outbreaks. Anthropogenic landscape changes such as forest loss, fragmentation and agricultural land uses are related with a boost in hantavirus reservoir species abundance and hantavirus prevalence in tropical areas, increasing HCPS risk. Additionally, higher precipitation, especially in arid regions, favors an increase in vegetational biomass, which augments the resources for reservoir rodents, also increasing HCPS risk. Although these relationships were observed, few studies described it so far, and the ones that did it are concentrated in few places. To guide future research on this issue, we build a conceptual model relating landscape and climate variables with HCPS outbreaks and identified research opportunities. We point out the need for studies addressing the effects of landscape configuration, temperature and the interaction between climate and landscape variables. Critical landscape thresholds are also highly relevant, once HCPS risk transmission can increase rapidly above a certain degree of landscape degradation. These studies could be relevant to implement preventive measures, creating landscapes that can mitigate disease spread risk.

Natural vegetation cover in the landscape and edge effects: differential responses of insect orders in a fragmented forest.

Human activities have led to global simplification of ecosystems, among which Neotropical dry forests are some of the most threatened. Habitat loss as well as edge effects may affect insect communities. Here, we analyzed insects sampled with pan traps in 9 landscapes (at 5 scales, in 100-500 m diameter circles) comprising cultivated fields and Chaco Serrano forests, at overall community and taxonomic order level. In total 7043 specimens and 456 species of hexapods were captured, with abundance and richness being directly related to forest cover at 500 m and higher at edges in comparison with forest interior. Community composition also varied with forest cover and edge/interior location. Different responses were detected among the 8 dominant orders. Collembola, Hemiptera, and Orthoptera richness and/or abundance were positively related to forest cover at the larger scale, while Thysanoptera abundance increased with forest cover only at the edge. Hymenoptera abundance and richness were negatively related to forest cover at 100 m. Coleoptera, Diptera, and Hymenoptera were more diverse and abundant at the forest edge. The generally negative influence of forest loss on insect communities could have functional consequences for both natural and cultivated systems, and highlights the relevance of forest conservation. Higher diversity at the edges could result from the simultaneous presence of forest and matrix species, although "resource mapping" might be involved for orders that were richer and more abundant at edges. Adjacent crops could benefit from forest proximity since natural enemies and pollinators are well represented in the orders showing positive edge effects.

Forest baseline and deforestation map of the Dominican Republic through the analysis of time series of MODIS data.

Deforestation is one of the major threats to habitats in the Dominican Republic. In this work we present a forest baseline for the year 2000 and a deforestation map for the year 2011. Maps were derived from Moderate Resolution Imaging Radiometer (MODIS) products at 250 m resolution. The vegetation continuous fields product (MOD44B) for the year 2000 was used to produce the forest baseline, while the vegetation indices product (MOD13Q1) was used to detect change between 2000 and 2011. Major findings based on the data presented here are reported in the manuscript "Habitat suitability and protection status of four species of amphibians in the Dominican Republic" (Sangermano et al., Appl. Geogr.,) [7].63, 2015, 55-65.

Descomposición de hojarasca en seis arroyos de Bosque Mesófilo de Montaña en la cuenca alta del río La Antigua, Veracruz, México

Leaf litter decomposition in six Cloud Forest streams of the upper La Antigua watershed, Veracruz, Mexico. Leaf litter decomposition is an important stream ecosystem process. To understand factors controlling leaf decomposition in cloud forest in Mexico, we incubated leaf packs in different streams along a land use cover gradient for 35 days during the dry and wet seasons. We assessed relations between leaf decomposition rates (k), stream physicochemistry, and macroinvertebrates colonizing leaf packs. Physicochemical parameters showed a clear seasonal difference at all study streams. Leaves were colonized by collector-gatherer insects, followed by shredders. Assessment of factors related to k indicated that only forest cover was negatively related to leaf decomposition rates. Thus stream physicochemistry and seasonality had no impact on decomposition rates. We concluded that leaf litter decomposition at our study streams is a stable process over the year. However, it is possible that this stability is the result of factors regulating decomposition during the different seasons and streams. Rev. Biol. Trop. 62 (Suppl. 2): 111-127. Epub 2014 April 01.

Para muchos arroyos, la hojarasca proveniente de la zona ribereña es la base de las redes tróficas, por lo cual el proceso de descomposición de la hojarasca es de gran importancia para el funcionamiento de estos ecosistemas. Con el fin de conocer los factores que afectan la descomposición de la hojarasca en arroyos del bosque mesófilo de montaña (BMM), se utilizaron paquetes de hojarasca durante 35 días. Seis arroyos con un gradiente de perturbación fueron estudiados en la época seca y lluviosa. Se determinó la relación entre la tasa de descomposición de la hojarasca (k), con algunos parámetros fisicoquímicos del cuerpo de agua y los macroinvertebrados colonizadores de los paquetes. Los factores fisicoquímicos mostraron una separación de los cuerpos de agua según la época a través de un Análisis de Componentes Principales (ACP). De los insectos colonizadores de los paquetes de hojarasca, el grupo funcional de los recolectores fue el más abundante, seguido por los fragmentadores. Solo se encontró una relación negativa entre la k y el porcentaje de cobertura boscosa (p=0.04) al realizar una regresión múltiple por pasos en la que se incluyeron algunos parámetros fisicoquímicos, el porcentaje de cobertura boscosa y las abundancias promedio de los insectos fragmentadores y no fragmentadores. La descomposición de la hojarasca en los arroyos estudiados parece ser un proceso estable a lo largo del año, aunque los factores responsables por la regulación pueden diferir en las distintas épocas.

Valoração ambiental do efeito externo da erosão em duas sub - bacias com diferentes percentuais de mata atlântica / Valuation of environmental effects of erosion in external two sub - watersheds with different percentages of forest atlantic

A equação universal de perda de solo (USLE) vem sendo utilizada para valorar os serviços ambientais de praticas conservacionistas e uso do solo em sub-bacias na quantificação da erosão e aporte de sedimentos. Neste sentido este trabalho objetivou comparar os resultados de perda de solo e de valoração ambiental obtido a partir da USLE com os valores mensurados no exutório de duas sub-bacias. A perda total de solo foi calculada utilizando técnicas de geoprocessamento e transformada em aporte de sedimentos e comparado ao aporte de sedimento observado no exutório da sub-bacias. A produção de sedimentos calculada e observada foi valorada considerando o custo de remoção de sedimentos do sistema de captação de água das microbacias. De forma geral, o modelo utilizado não apresentou bom ajuste para a quantificação do aporte de sedimentos nas sub-bacias Glória e Palmital, superestimando os valores medidos nas respectivas áreas. De acordo com a valoração ambiental pelo custo de retirada de sedimentos observou-se que a microbacia com maior cobertura florestal reduz o aporte de sedimentos e gera mais serviços ambientais reduzindo os custos de retirada de sedimentos na captação de água.

The Universal Soil Loss Equation (USLE) has been used to appraise the environmental services of the conservation practices and land use in sub - watersheds in the quantification of erosion and sediment delivery. In this sense this study compares the results of soil loss and environmental valuation obtained from the USLE model with the values measured in the discharge of water of both watersheds. The total soil loss was calculated using GIS techniques and transformed into sediment delivery and then compared to the production of sediment observed in the discharge watersheds. The sediment production rate was calculated and valued considering the cost of sediment removal from water catchment system. In general, the model used did not show goodfit for quantification of sediment delivery in sub - watersheds Gloria and Palmital, overestimating the values measured in the respective areas. According to evaluation by environmental cost of removing sediment was observed that the more sub ­ watershed forest cover reduces the accumulation of sediments creates more environmental services and reducing the costs of removal of sediment in the water uptake.

Differences in seed rain composition in small and large fragments in the northeast Brazilian Atlantic Forest.

Tropical forests are seriously threatened by fragmentation and habitat loss. The impact of fragment size and forest configuration on the composition of seed rain is insufficiently studied. For the present study, seed rain composition of small and large forest fragments (8-388 ha) was assessed in order to identify variations in seed abundance, species richness, seed size and dispersal mode. Seed rain was documented during a 1-year period in three large and four small Atlantic Forest fragments that are isolated by a sugarcane matrix. Total seed rain included 20,518 seeds of 149 species of trees, shrubs, palms, lianas and herbs. Most species and seeds were animal-dispersed. A significant difference in the proportion of seeds and species within different categories of seed size was found between small and large fragments. Small fragments received significantly more very small-sized seeds (<0.3 cm) and less large-seeded species (>1.5 cm) that were generally very rare, with only one species in small and eight in large fragments. We found a negative correlation between the inflow of small-sized seeds and the percentage of forest cover. Species richness was lower in small than in large fragments, but the difference was not very pronounced. Given our results, we propose changing plant species pools through logging, tree mortality and a high inflow of pioneer species and lianas, especially in small forest fragments and areas with low forest cover. Connecting forest fragments through corridors and reforestation with local large-seeded tree species may facilitate the maintenance of species diversity.

Relief influence on the spatial distribution of the Atlantic Forest cover on the Ibiúna Plateau, SP

Several studies suggest that, on a large scale, relief conditions influence the Atlantic Forest cover. The aim of this work was to explore these relationships on a local scale, in Caucaia do Alto, on the Ibiúna Plateau. Within an area of about 78 km², the distribution of forest cover, divided into two successional stages, was associated with relief attribute data (slope, slope orientation and altitude). The mapping of the vegetation was based on the interpretation of stereoscopic pairs of aerial photographs, from April 2000, on a scale of 1:10,000, while the relief attributes were obtained by geoprocessing from digitalized topographic maps on a scale of 1:10,000. Statistical analyses, based on qui-square tests, revealed that there was a more extensive forest cover, irrespective of the successional stage, in steeper areas (>10 degrees) located at higher altitudes (>923 m), but no influence of the slope orientation. There was no sign of direct influence of relief on the forest cover through environmental gradients that might have contributed to the forest regeneration. Likewise, there was no evidence that these results could have been influenced by the distance from roads or urban areas or with respect to permanent preservation areas. Relief seems to influence the forest cover indirectly, since agricultural land use is preferably made in flatter and lower areas. These results suggest a general distribution pattern of the forest remnants, independent of the scale of study, on which relief indirectly has a strong influence, since it determines human occupation.

Vários estudos sugerem que as condições do relevo influenciam, em larga escala, a cobertura da Mata Atlântica. Este trabalho teve por objetivo explorar estas relações em escala local, na região do Planalto de Ibiúna, denominada de Caucaia do Alto. Numa área de cerca de 78 km², procurou-se associar a cobertura florestal, dividida em dois estádios sucessionais, com atributos do relevo (declividade, orientação de vertente e altitude). O mapeamento da vegetação foi feito a partir da interpretação de pares estereoscópicos de fotografias aéreas de abril de 2000, na escala 1:10.000, enquanto os atributos do relevo foram gerados por geoprocessamento a partir de cartas topográficas digitalizadas, em escala 1:10.000. As análises estatísticas, baseadas em testes de qui-quadrado, revelam que há maior cobertura florestal, independentemente do estádio sucessional, em áreas mais íngremes (>10 graus) e situadas em altitudes mais elevadas (>923 m), porém não há influência da orientação de vertente. Não há indícios de influência direta do relevo sobre a cobertura florestal, através de gradientes ambientais que poderiam agir na regeneração florestal. Também não foram obtidas evidências de que estes resultados possam ser influenciados pelo distanciamento a estradas ou centros urbanos, ou ainda pelo respeito às áreas de preservação permanente. O relevo parece determinar o recobrimento florestal, principalmente por condicionar o uso agrícola dos solos, que se dá preferencialmente em áreas mais planas e baixas. Estes resultados sugerem um padrão geral de influência do relevo sobre a distribuição dos remanescentes florestais, independentemente da escala de estudo, onde o relevo atua indiretamente ao condicionar a ocupação humana.

Relief influence on the spatial distribution of the Atlantic Forest cover on the Ibiúna Plateau, SP

Several studies suggest that, on a large scale, relief conditions influence the Atlantic Forest cover. The aim of this work was to explore these relationships on a local scale, in Caucaia do Alto, on the Ibiúna Plateau. Within an area of about 78 km², the distribution of forest cover, divided into two successional stages, was associated with relief attribute data (slope, slope orientation and altitude). The mapping of the vegetation was based on the interpretation of stereoscopic pairs of aerial photographs, from April 2000, on a scale of 1:10,000, while the relief attributes were obtained by geoprocessing from digitalized topographic maps on a scale of 1:10,000. Statistical analyses, based on qui-square tests, revealed that there was a more extensive forest cover, irrespective of the successional stage, in steeper areas (>10 degrees) located at higher altitudes (>923 m), but no influence of the slope orientation. There was no sign of direct influence of relief on the forest cover through environmental gradients that might have contributed to the forest regeneration. Likewise, there was no evidence that these results could have been influenced by the distance from roads or urban areas or with respect to permanent preservation areas. Relief seems to influence the forest cover indirectly, since agricultural land use is preferably made in flatter and lower areas. These results suggest a general distribution pattern of the forest remnants, independent of the scale of study, on which relief indirectly has a strong influence, since it determines human occupation.

Vários estudos sugerem que as condições do relevo influenciam, em larga escala, a cobertura da Mata Atlântica. Este trabalho teve por objetivo explorar estas relações em escala local, na região do Planalto de Ibiúna, denominada de Caucaia do Alto. Numa área de cerca de 78 km², procurou-se associar a cobertura florestal, dividida em dois estádios sucessionais, com atributos do relevo (declividade, orientação de vertente e altitude). O mapeamento da vegetação foi feito a partir da interpretação de pares estereoscópicos de fotografias aéreas de abril de 2000, na escala 1:10.000, enquanto os atributos do relevo foram gerados por geoprocessamento a partir de cartas topográficas digitalizadas, em escala 1:10.000. As análises estatísticas, baseadas em testes de qui-quadrado, revelam que há maior cobertura florestal, independentemente do estádio sucessional, em áreas mais íngremes (>10 graus) e situadas em altitudes mais elevadas (>923 m), porém não há influência da orientação de vertente. Não há indícios de influência direta do relevo sobre a cobertura florestal, através de gradientes ambientais que poderiam agir na regeneração florestal. Também não foram obtidas evidências de que estes resultados possam ser influenciados pelo distanciamento a estradas ou centros urbanos, ou ainda pelo respeito às áreas de preservação permanente. O relevo parece determinar o recobrimento florestal, principalmente por condicionar o uso agrícola dos solos, que se dá preferencialmente em áreas mais planas e baixas. Estes resultados sugerem um padrão geral de influência do relevo sobre a distribuição dos remanescentes florestais, independentemente da escala de estudo, onde o relevo atua indiretamente ao condicionar a ocupação humana.