Marco Aurélio Leite Fontes

Patterns of Floristic Differentiation among Atlantic Forests in Southeastern Brazil and the Influence of Climate1

The tree flora of southeastern Brazilian Atlantic forests was investigated according to two main aspects: (a) the variations in floristic composition of both rain and semi-deciduous forests were analyzed in terms of geographic and climatic variables by performing multivariate analyses on 125 existing floristic checklists; and (b) the links of both rain and semideciduous forests to Amazonian forests and Cerrados (woody savanna) were assessed. All analyses were performed at the species, genus, and family levels. The information obtained for the 125 forest areas was organized into an environmental darabase containing geographic and climatic records, and a floristic database containing binary presence records for 2532 species, 520 genera, and 106 families. Canonical correspondence analyses (CCA) were utilized to assess the relationship between geographic and climatic variables, and tree flora composition. Venn diagrams and cluster analyses were used to assess the floristic links to Amazonian forests and Cerrados. The following patterns were detected at all three taxonomic levels: (a) the differentiation between rain and semi-deciduous forests is floristically consistent and strongly correlated with rainfall regime, although transitions may be abrupt to gradual; (b) a north-south differentiation exists for both rain and semi-deciduous forests, probably caused by variations in both temperature and rainfall regime; (c) The flora of semideciduous forests also changes with increasing distance from the ocean and the associated increasing rainfall seasonality; and (d) elevation and associated temperatures are strongly correlated with the internal differentiation of both rain and semi-deciduous forests. To a considerable extent, the tree flora of semi-deciduous forests is a subset of the rain forest flora, probably extracting species that are able to cope with a longer dry season. There is greater floristic similarity at the species level between Atlantic rain and semi-deciduous forests than between any of these and either Amazonian rain forests or Cerrados. Nevertheless, semi-deciduous forests and Cerrados show stronger links, particularly at the generic and familial levels. Therefore, there is little floristic ground for viewing Atlantic rain forests as being closer to their Amazonian counterparts than to the adjacent semi-deciduous forests. The most appropriate view of rain and semideciduous forests in southeastern Brazil is rhat of a continuum in tree species distribution. We suggest that the definition of Atlantic forests should be as comprehensive as that of Amazonian forests.

Comunidade arbórea de um continuum entre floresta paludosa e de encosta em Coqueiral, Minas Gerais, Brasil

The purpose of the present contribution was to describe the community of trees of a continuum extending from swampy to upland forest in Coqueiral, SE Brazil, assessing the correlations between the variations of community structure and those of the environment. Sampling was carried out in 25 plots of 20 X 20 m laid on the forest fragment to survey trees with a minimum circumference of 15.5 cm (registering their circumference, height and species) as well as topographic and soil variables. Species-environment correlations were analyzed using canonical correspondence analysis (CCA) and Spearmans test. The swampy and upland habitats differed substantially in both community structure and floristic composition. The general floristic profile was similar to that of other riparian forests of the Mid and Upper Rio Grande region, whilst the swampy portion of the forest differed from what is commonly found in SE Brazil. The species distribution was correlated mainly to soil drainage and proximity to the lake. The high soil diversity and the strong soil moisture gradient found over a small area resulted in different habitats and a diverse community of trees and shrubs that combined phyto-physiognomies of semideciduous and swampy forests, along with cerrado patches.

Diversity and structure of the tree community of a fragment of tropical secondary forest of the brazilian Atlantic Forest domain 15 and 40 years after logging

Two adjacent tracts of tropical secondary forest, situated in Itambe do Mato Dentro, south-eastern Brazil, which had been regenerating for 15 and 40 years after clearing, were compared with the purpose of detecting differences in species diversity and composition, species guild composition (regeneration, stratification and dispersion), and stand structure. Four and three 1,125 m2 plots laid on the 15- and 40-year-old stands, respectively, sampled 2,430 trees with diameter at the base of the stem > 5 cm. The number of species (S = 199) was high for this forest type and significantly higher for the older stand. Tree density was significantly higher in the younger stand, particularly for smaller trees, whereas the two stands did not differ in both basal area and volume per hectare. Trees of shade-tolerant and understory species were significantly more abundant in the older stand. Though sharing a large proportion of species (49%), the two stands differed significantly in the abundance of many species. Live stumps probably contributed to the relatively quick restoration of some forest characteristics, particularly species diversity, basal area and volume.

Potential of natural regeneration as a method of restoration of degraded land surrounding water springs

This work evaluated the potential of natural regeneration in the restoration a disturbed water spring surrouding, after stopping the impacts, on forest and wasted grazing land. It was analyzed the structure of the stratum and natural regeneration under canopy and in open area surrounding a water spring under process of recovery, located in Nazareno, Minas Gerais. The tree stratum was assessed in 4 permanent plots (10 × 50 m), sampling, identifying and measuring height of trees with DBH  5 cm diameter. For assessing the natural regeneration, 16 plots (10 × 2 m) were set. Trees with height> 10 cm and DBH <5 cm were identified and measured. The samples were established at 7 and 51 months after the isolation of the area. Phytosociological parameters of the tree and regenerative strata were calculated for each species, classifying them by the type of dispersal and ecological group. Shannon diversity index and evenness were calculated for each community which were also compared by Sorensen index. The results showed that the areas are dissimilar, with most species found at the regeneration under canopy, showing a intake in the system. The communities had a high proportion of zoochoric species and pattern of higher light demanding climax species and a decrease in the proportion of pioneer species from one inventory to another, indicating progress in natural succession. The density of the individuals regenerating under canopy was much greater, probably due to the dominance of Brachiaria in the open area, showing that use of the regeneration as a unique method of recovery should not be applied.

Species composition and floristic relationships in southern Goiás forest enclaves

Os fragmentos de Mata Atlântica interioranos localizam-se em regiao de tensao ecologica e carecem de conhecimento sobre os efeitos de impactos antropicos sobre sua composicao e regeneracao. Objetivou-se caracterizar e descrever a estrutura e composicao da comunidade arborea em remanescentes florestais localizados em Itumbiara, Goias, alem de analisar as relacoes floristicas entre esses e outros fragmentos de formacoes estacionais e de areas ecotonais. Foram selecionados cinco fragmentos para a amostragem da comunidade arborea. Foi aplicado o metodo de quadrantes, sendo alocados, em cada fragmento, transeccoes lineares contendo 25 pontos, o que resultou no estabelecimento de 125 unidades amostrais. Em cada ponto, foram inventariados os especimes arboreos vivos com circunferencia a 1,30 m acima do solo >15 cm. As coletas floristicas e o levantamento fitossociologico registraram 149 especies arboreas, pertencentes a 110 generos e distribuidas em 47 familias. A analise de similaridade demonstrou o carater ecotonal, com muitas especies generalistas e outras de ocorrencia mais pontual no Cerrado ou em matas estacionais. Os remanescentes florestais em Itumbiara apresentaram elevada diversidade arborea. No entanto, a comunidade arborea sugere relacoes floristicas mais estreitas com as formacoes savânicas.

Relações solo-vegetação na estruturação de comunidades de cerrado sensu stricto no sul de Minas Gerais, Brasil

Os cerrados do sul de Minas Gerais ainda sao pouco estudados. Objetivou-se com esse trabalho compreender o papel dos solos na estruturacao de duas comunidades arboreas de cerrado no municipio de Guape. Para isso, foram instaladas 14 parcelas de 50 × 30 m em dois fragmentos de cerrado sendo 8 sobre Neossolo Litolico e 6 sobre Argissolo Vermelho. Nessas parcelas, todos os individuos arboreos com circunferencia a 30 cm do solo (C30) ≥ 15,7 cm (diâmetro de 5 cm) foram medidos e tiraram-se amostras de solo de cada parcela para analises quimicas e texturais. Ao todo foram amostrados 1561 individuos e a riqueza floristica total foi de 83 especies pertencentes a 65 generos de 37 familias. A area sobre Neossolo foi classificada como cerrado sensu stricto rupestre e Caryocar brasiliense foi a especie mais importante em VI para a fisionomia. O cerrado sobre Argissolo foi categorizado como um cerrado sensu stricto tipico e Dalbergia miscolobium foi a especie de maior VI para essa fitofisionomia. A analise de correspondencia canonica apresentou autovalor significativo para o primeiro eixo de 0,563 indicando gradiente curto com rapida substituicao de especies. Encontrou-se associacao aos teores de P e areia no cerrado rupestre e de K e argila no cerrado tipico. Por fim, a distribuicao das especies no gradiente foi diferente entre os substratos indicando preferencia de especies por sitios especificos. A conservacao dos cerrados do sul de Minas Gerais deve, portanto, considerar nao apenas a diversidade floristica, mas suas multiplas pedoformas e as formacoes ecotonais associadas.

Regeneração natural em áreas desmatadas e dominadas por Pteridium aquilinum (L.) Kuhn. na Serra da Mantiqueira

Objetivou-se analisar a sucessao ecologica em areas desmatadas e dominadas espontaneamente por Pteridium aquilinum na Serra da Mantiqueira, por meio do levantamento da regeneracao natural de especies arbustivo-arboreas, bem como avaliar a influencia dos historicos de perturbacao e condicoes edaficas. Amostraram-se duas areas em Bocaina de Minas, Minas Gerais, em regeneracao ha 6 e 20 anos, com 60 parcelas de 10 m², inventariando-se os regenerantes de 0,15 a 3 m de altura, todos identificados e medidos em diâmetro e altura. Registraram-se 1.159 individuos de 53 especies, destacando-se a familia Melastomataceae pela maior riqueza e abundância. As areas diferenciaram-se na composicao de especies, com similaridade de Jaccard de 3,7%. Sob analise de correspondencia canonica, a area de seis anos evidenciou correlacoes positivas entre a comunidade regenerante e teores de fosforo nao labil e argila, enquanto a area de 20 anos mostrou correlacoes com K, P, Ca, Al, pH e soma de bases trocaveis, alem de maiores densidades de Pteridium. Os resultados demonstraram que a dominância de P. aquilinum conduz a uma sucessao ecologica sob inibicao, onde a samambaia atua negativamente sobre a riqueza e abundância de populacoes arbustivo-arboreas. Tambem se confirmou a preferencia da especie por terrenos declivosos, a maiores altitudes, com solos mais acidos, beneficiando-se tambem de disturbios. Por outro lado, chama-se a atencao para a suscetibilidade desses ambientes montanos e para a importância da preservacao de sua vegetacao natural, assim como do desbaste das samambaias como estrategia de restauracao florestal.

Tree diversity of small forest fragments in ecotonal regions: why must these fragments be preserved?

Descriptions of biodiversity from ecotonal regions are lacking. This knowledge gap results from the difficulty of identifying elements from both biomes/domains and the advancement of human activities that generate small forest fragments. Here it is shown that small forest fragments in an ecotonal region have species richness and abundance in line with other inventories in preserved and non-preserved areas as well as composition and structure differentiated by the presence of species from both domains. The beta diversity among fragments reflects a high turnover supported by the formation of centers of dominance among the most abundant species. Finally, functional diversity favors the group that is tolerant of a wide range of environmental variables and is associated with faunal components. The results indicate that these fragments are important from a conservation standpoint because of the intersection of elements from threatened biomes, which must be managed coherently. However, Brazilian legislation is constantly modified and still allows anthropogenic changes that prevent the persistence of species.

Alometria e arquitetura de Copaifera langsdorffii (Desf.) Kuntze (Fabaceae) em fitofisionomias neotropicais no sul de minas gerais

O objetivo deste trabalho foi analisar padroes alometricos e feicoes arquiteturais de Copaifera langsdorffii em diferentes fisionomias de uma regiao de tensao ecologica. As fisionomias de floresta, corredor, cerrado e cerrado rupestre foram estudadas nos municipios de Lavras e Carrancas, sul de Minas Gerais, Brasil. Foram estudadas as relacoes entre diâmetro do tronco, altura, area da copa, grau de deflexao e deslocamento relativo da copa, sendo analisado o grau de semelhanca, entre as fisionomias, por meio de regressoes e analise covariância. Foi realizada uma analise de componentes principais (PCA) com variaveis biometricas coletadas e morfometricas calculadas, para caracterizacao de grupos mais homogeneos que evidenciem a plasticidade morfologica da especie e suas diferentes estrategias e investimento em recursos. Como resultado das analises de regressao e covariância, encontraram-se padroes distintos, principalmente entre as fisionomias de floresta e cerrado, das fisionomias de cerrado rupestre e corredor. Um padrao de crescimento com maior investimento em altura na floresta, objetivando a garantia de espaco no dossel, e outro mais ligado ao crescimento horizontal da copa, nas fisionomias de cerrado rupestre e corredor. A PCA apresentou um gradiente de plasticidade morfologica para a especie. A fisionomia de floresta apresentou maiores valores de altura total, largura de copa e diâmetro do tronco, e a fisionomia de cerrado rupestre mostrou valores mais elevados de grau de deflexao da copa (assimetria). O cerrado e o corredor formaram uma transicao entre floresta e cerrado rupestre, no gradiente de feicoes morfologicas da especie nas fisionomias.

Water Availability Drives Gradients of Tree Diversity, Structure and Functional Traits in the Atlantic-Cerrado-Caatinga Transition, Brazil

Aims Climate and soil are among the most important factors determining variation in tree communities, but their effects have not been thoroughly elucidated to date for many vegetation features. In this study, we evaluate how climate and soil gradients affect gradients of vegetation composition, species diversity and dominance, structure and functional traits (seed mass and wood density) using over 327 000 trees in 158 sites distributed along environmental gradients in the transitions among the Atlantic forest, Cerrado and Caatinga in Minas Gerais State (MG), Brazil (nearly 600 000 km 2). Methods Gradients in species, genus and family abundance in addition to basal area, stem density, species diversity (Fishers alpha), dominance percentage, seed mass and wood density were correlated using multiple regressions with environmental variables, as summarized in four principal component analysis axes (two climatic - precipitation seasonality and temperature range - and two edaphic - soil fertility and soil moisture). Additionally, ordinary kriging maps were used to better illustrate the gradients. Important Findings Multiple regression models indicate that all variables but dominance percentage were affected by one or more of the environmental gradients, but the average R 2 was low (26.25%). Kriging maps reinforced the patterns observed in the regression models. Precipitation seasonality and soil moisture gradients were the most important gradients affecting vegetation features. This finding suggests that water availability is an important determinant of vegetation features in these vegetation transitions.