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Patches of natural vegetation remaining in landscapes occupied by man are continuously under threat due to the edge effects and also to land use types around these remnants. The most frequent threats and land use types in the vicinity of 81 Cerrado (tropical savanna type) fragments in the State of São Paulo, Brazil, were analyzed in order to verify if the frequency of every type of disturbance to the natural ecosystem depends on the neighboring land use. The hypothesis of the study assumes that environmental threats are correlated with land use around protected areas. From the 81 areas, the most frequent human-induced land cover types around the Cerrado remnants were: pasture (recorded in 78% of the areas), sugarcane plantations (26%), roads (19%), annual crops and reforestation (14% each). The most frequent sources of threats were invasive grasses (35% of the areas partially or totally invaded) and cattle (observed in 32% of the areas), followed by deforestation (21%), and fire (21%). The chi-square analysis revealed that, with the exception of deforestation, which does not depend on land use, all other threats are influenced by the neighboring land use. The occurrence of invasive grasses and fires are strongly favored by the presence of roads and urban areas. Sugarcane, reforestation, and permanent crops were the less impacting land use types found in the study area, when only considering impact frequency. These land use types have fire and weed control, and also exclude cattle, indirectly protecting natural ecosystems. Key words: savanna, conservation, impact, fragmentation, land use AMEAÇAS A FRAGMENTOS DE CERRADO NO ESTADO DE SÃO PAULO, BRASILRESUMO: Fragmentos remanescentes de vegetação natural em paisagens antropizadas sofrem ameaças permanentes, devido aos efeitos de borda e às atividades antrópicas nas áreas limítrofes. Para verificar a hipótese de que o tipo de ameaça ao ecossistema e a sua freqüência dependem do uso da terra no seu entorno, foram analisados 81 fragmentos de Cerrado no estado de São Paulo. Para cada fragmento foram registrados os tipos de perturbação no ecossistema e os tipos de uso da terra no seu entorno. Os usos mais freqüentes foram pastagens cultivadas (registradas em 78% das áreas), plantio de canade-açúcar (26%), rodovias (19%), reflorestamento (14%) e culturas anuais (14%). As ameaças mais freqüentemente registradas foram gramíneas invasoras (35% das áreas parcial ou totalmente invadidas), presença de gado (32%), desmatamento (21%) e fogo (21%). A análise da freqüência observada de cada tipo de impacto mediante a freqüência esperada caso não houvesse influência do uso da terra (qui-quadrado), mostrou que as ameaças dependem do uso da terra nas áreas ao redor dos fragmentos, exceto para o desmatamento, que tem ocorrido indiferentemente ao tipo de uso. Gramíneas invasoras e fogo são muito mais freqüentes na vizinhança de rodovias e zonas urbanas, enquanto que o plantio de cana-de-açúcar, silvicultura e fruticultura têm sido os usos da terra menos impactantes para a vege...

a b s t r a c tSpecies' potential distribution modelling consists of building a representation of the fundamental ecological requirements of a species from biotic and abiotic conditions where the species is known to occur. Such models can be valuable tools to understand the biogeography of species and to support the prediction of its presence/absence considering a particular environment scenario. This paper investigates the use of different supervised machine learning techniques to model the potential distribution of 35 plant species from Latin America. Each technique was able to extract a different representation of the relations between the environmental conditions and the distribution profile of the species. The experimental results highlight the good performance of random trees classifiers, indicating this particular technique as a promising candidate for modelling species' potential distribution.

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Species' potential distribution modelling is the process of building a representation of the fundamental ecological requirements for a species and extrapolating these requirements into a geographical region. The importance of being able to predict the distribution of species is currently highlighted by issues like global climate change, public health problems caused by disease vectors, anthropogenic impacts that can lead to massive species extinction, among other challenges. There are several computational approaches that can be used to generate potential distribution models, each achieving optimal results under different conditions. However, the existing software packages available for this purpose typically implement a single algorithm, and each software package presents a new learning curve to the user. Whenever new software is developed for species' potential distribution modelling, significant duplication of effort results because many feature requirements are shared between the different packages. Additionally, data preparation and comparison between algorithms becomes difficult when using separate software applications, since each application has different data input and output capabilities. This paper describes a generic approach for building a single computing framework capable of handling different data formats and multiple algorithms that can be used in potential distribution modelling. The ideas described in this paper have been implemented in a free and open source software package called openModeller. The main concepts of species' potential distribution modelling are also explained and an example use case illustrates potential distribution maps generated by the framework. Geoinformatica (2011) 15:111-135

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The present study applies a series of new techniques to understand the conservation of Cerrado tree species in the face of climate change. We applied techniques from the emerging field of ecological niche modeling to develop a first-pass assessment of likely effects of climate change on tree species' distributions in the Cerrado biome by relating known occurrence points to electronic maps summarizing ecological dimensions. Distributional data represent 15,657 records for 162 tree species occurring in Cerrado. By focusing on the trees of one important and highly endemic biome, rather than the biota of a political unit, we were able to focus on developing biome-wide projections. An important limitation of this study is that only those species with more than 30 unique occurrence records were used-hence, the study is limited to those species of relatively broad geographic distribution, and does not take into account those species with narrower geographic distributions. Global climate change scenarios considered were drawn from the general circulation models of HadCM2; we assessed both a conservative and a less conservative scenario of how climates could change over the next 50 year using the (Hadley HHGSDX50 and HHGGAX50 scenarios, respectively): HHGSDX50 assumes 0.5%/yr CO2 increase, whereas HHGGAX50 assumes a 1%/yr CO2 increase. Results of predictions of present and future distributions varied widely among species. Present distributional models predicted areas of 655,211-2,287,482 out of the 2,496,230 km 2 core area of Cerrado in Brazil. All models used to represent species' present geographic ranges were highly statistically significant based on independent test data sets of point localities. Most species were projected to decline seriously in potential distributional area, with both scenarios anticipating losses of >50% of potential distributional area for essentially all species. Indeed, out of 162 species examined, between the two climate change scenarios, 18 (HHGSDX50 scenario) -56 (HHGGAX50 scenario) were predicted to end up without habitable areas in the Cerrado region, and 91 (HHGSDX50 scenario) -123 (HHGGAX50 scenario) species were predicted to decline by more than 90% in potential distributional area in the Cerrado region. Bearing in mind the limitations of the method, and considering its explicit assumptions, these results nevertheless should be cause for ample concern regarding Cerrado biodiversity. Since only 2.25% of the Cerrado biome is presently protected, this future scenario presents a pessimistic forecast, which would likely include widespread species loss from the biome, as well as dramatic shifts to the south and east, further complicating conservation planning efforts.