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The aim of this study was to evaluate the ecological niche models (ENMs) for three specialist trees (Anadenanthera colubrina, Aspidosperma pyrifolium and Myracrodruon urundeuva) in seasonally dry tropical forests (SDTFs) in Brazil, considering present and future pessimist scenarios (2080) of climate change. These three species exhibit typical deciduousness and are widely distributed by SDTF in South America, being important in studies of the historical and evolutionary processes experienced by this ecosystem. The modeling of the potential geographic distribution of species was done by the method of maximum entropy (Maxent). We verified a general expansion of suitable areas for occurrence of the three species in future (c.a., 18%), although there was reduction of areas with high environmental suitability in Caatinga region. Precipitation of wettest quarter and temperature seasonality were the predictor variables that most contributed to our models. Climatic changes can provide more severe and longer dry season with increasing temperature and tree mortality in tropics. On this scenario, areas currently occupied by rainforest and savannas could become more suitable for occurrence of the SDTF specialist trees, whereas regions occupied by Caatinga could not support the future level of unsustainable (e.g., aridity). Long-term multidisciplinary studies are necessary to make reliable predictions of the plant's adaptation strategies and responses to climate changes in dry forest at community level. Based on the high deforestation rate, endemism and threat, public policies to minimize the effects of climate change on the biodiversity found within SDTFs must be undertaken rapidly.Keywords: Caatinga biome, deciduous forest, ecological niche model, geographical species distribution. Efeitos das mudanças climáticas sobre a distribuição geográfica de espécies arbóreas especialistas de florestas secas tropicais brasileiras ResumoEste estudo tem como objetivo avaliar a modelagem de nicho ecológico (ENMs) para três espécies especialistas (Anadenanthera colubrina, Aspidosperma pyrifolium e Myracrodruon urundeuva) de florestas tropicais secas (FTSs) no Brasil, considerando o cenário de mudanças climáticas: presente e futuro pessimistas (2080). Estas três espécies são decíduas e amplamente distribuídas pelas FTSs na América do Sul, sendo importante em estudos sobre os processos históricos e evolutivos experimentados por este ecossistema. A modelagem da distribuição geográfica potencial das espécies foi construída através do método de máxima entropia (Maxent). Foi observada uma expansão geral de áreas adequadas para a ocorrência das três espécies no futuro (cerca de 18%), embora tenha existido uma redução das áreas com alta adequabilidade ambiental na região da Caatinga. A precipitação do trimestre mais úmido e a sazonalidade da temperatura foram os fatores que mais contribuíram para os nossos modelos. As mudanças climáticas podem gerar períodos secos mais severos e longos, com aumento da temperatura e mortalidade de árvores ...

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The semiarid region of Brazil consists of a great variety of landscapes, soils and vegetation forms, with complex interrelations. In order to better understand this interplay, we posed two questions: Are there greater pedological similarities among the different landforms of the same catena or among the same landforms from different catenas? Which soil attributes could be the most important to segregate communities of plants? We sampled soils and vegetation on different landforms in four different catenas and performed NMS (non-metric multidimensional scaling) and ANOVA (analysis of variance) to address the first question; also, we carried another NMS following GLM (general linear model regression) to answer the second question. The first NMS indicated the existence of a fertility gradient, grouping communities in relation to similar landforms, confirmed by ANOVA. The second NMS indicated the same gradient whereas the GLM showed that is controlled by aluminum saturation, sodium saturation, phosphorous and sand content. One extreme of the gradient has uplands associated with cerrado vegetation forms whereas the other extreme slopes were associated with dry forests. The lowlands associated with dry forest represent the central position of the fertility gradient. In general, soils at similar landforms showed greater pedological similarity, and their physico-chemical attributes determined the formation and structure of vegetation. This similarity across the same landform refers to the Folia Geobot comparable soil formation at each landform and soil age at landscape scale. The characteristics of the vegetation and soils in the Brazilian southern semiarid region indicated a previously wetter climate, during which deep weathered latosols (oxisols) were formed and remain as relics in the present semiarid.

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The licuri palm, Syagrus coronata (Martius) Beccari (Arecaceae), is widely distributed throughout the Brazilian Caatinga and has high cultural, socioeconomical, and ecological importance. The palm tree logging is prohibited by the Brazilian law, and thus isolated individuals are a common sight on managed pastures in the Brazilian semi-arid region. We aimed to compare the insect seed-predator Pachymerus nucleorum (Fabricius) (Bruchinae) abundance and its predation levels on S. coronata seeds between managed (pasture) and natural (Caatinga vegetation) habitats. We also monitored the parasitoid Heterospilus prosopodis (Viereck) (Braconidae) abundance and other P. nucleorum potential natural enemies (generalist predators and microhymenopterans). We tested the hypothesis that more complex and heterogenous habitats (i.e., with higher plant diversity) support higher abundance of potential P. nucleorum natural enemies. For such, we collected 600 fruits from each habitat and evaluated the seed predation level by P. nucleorum, as well as the P. nucleorum parasitism by H. prosopodis. The P. nucleorum abundance and its potential natural enemies were estimated using 122 sticky traps placed on the S. coronata individuals' crown. Neither the P. nucleorum and generalist predators abundance differed between habitats, whereas the H. prosopodis and microhymenopterans abundance was higher in the natural habitat. Consequently, P. nucleorum parasitism levels by H. prosopodis were also higher in the natural habitat. Our study indicated that habitat with higher plant diversity supported more natural enemies, thus confirming that increased habitat homogenization leads to decreased parasitism levels by the less parasitoids number in managed habitats. Our results may subsidize conservationist management practices in the managed habitats aiming to improve fruit exploitation techniques sustainability and land-use practices, which would thereafter allow for the S. coronata population conservation in the Brazilian Caatinga.