ABSTRACT The Caatinga biome in Brazil comprises the largest and most continuous expanse of the seasonally dry tropical forest (SDTF) worldwide; nevertheless, it is among the most threatened and least studied, despite its ecological and biogeographical importance. The spatial distribution of volumetric wood stocks in the Caatinga and the relationship with environmental factors remain unknown. Therefore, this study intends to quantify and analyze the spatial distribution of wood volume as a function of environmental variables in Caatinga vegetation in Bahia State, Brazil. Volumetric estimates were obtained at the plot and fragment level. The multiple linear regression techniques were adopted, using environmental variables in the area as predictors. Spatial modeling was performed using the geostatistical kriging approach with the model residuals. The model developed presented a reasonable fit for the volume m3 ha with r2 of 0.54 and Root Mean Square Error (RMSE) of 10.9 m3 ha–1. The kriging of ordinary residuals suggested low error estimates in unsampled locations and balance in the under and overestimates of the model. The regression kriging approach provided greater detailing of the global wood volume stock map, yielding volume estimates that ranged from 0.01 to 109 m3 ha–1. Elevation, mean annual temperature, and precipitation of the driest month are strong environmental predictors for volume estimation. This information is necessary to development action plans for sustainable management and use of the Caatinga SDTF in Bahia State, Brazil.

ABSTRACT The distribution modeling in diameter classes is an important indicator of the potential use of a forest community, as well as the projection of future forest production. The objective of this study was to evaluate the diametric structure and to select probabilistic density functions for three woody species in forested arboreal Caatinga vegetation in Bahia, Brazil. The study was carried out in the Contendas do Sincorá National Forest in the state of Bahia, Brazil. A total of 16 plots of 20 x 20 m were installed and all individuals with diameter at breast height equal to or greater than 5.0 cm were measured. The three species with the highest population density (Commiphora leptophloeos, Manihot catinga and Patagonula bahiensis) were selected for analysis and modeling of the diametric structure. Four probabilistic density models were adjusted. The Akaike information criterion was used to select the best model. The results found indicated that the three species presented a decreasing type curve. The Log-Normal function best described the diametric distribution and it can be indicated to describe the diametric distribution and assist in making decisions about the management and conservation of these species. It is concluded that the Normal function was less adequate to represent the distribution of the studied species.

ABSTRACT The objective of this work was to characterize the population structure, analyze the spatial distribution pattern and identify the potential use of the Commiphora leptopholoeos in the Contendas do Sincorá National Forest, BA. Thus, three disjoint transects of 40 x 160 m were installed for the phytosociological study and spatial distribution and subdivided into 64 plots of 10 x 10 m, for which the density and frequency values of regenerating individuals (dbh < 5 cm), and the density, frequency and basal area of arboreal size were calculated (dbh ≥ 5 cm). The spatial distribution pattern was calculated by the Morisita index, Payandeh’s dispersion index and the Chi-squared test for the different populations. The diametric distribution was in the form of a reverse J-shaped, usually indicate full regeneration with constant seed production, germination and recruitment. The stems of the species were mostly healthy, but with a large tillering percentage and tortuosity below the commercial height, constituting characteristics which favor uses for firewood, stakes and poles. The spatial distribution pattern values of the species for tree size and regeneration point to an aggregate spatial distribution or to a tendency to aggregation.

ABSTRACT Dynamics studies associated with prognosis can support planning actions for the conservation and sustainable use of forest resources. Therefore, the objective of this study was to evaluate the dynamics and predict the diameter structure using the Markov chain model for an area of caatinga forest submitted to different management practices. The study was carried out in the Contendas do Sincorá National Forest in the state of Bahia. Four treatments were installed, corresponding to three management systems and one control. Data was obtained measuring all individuals with a diameter greater than or equal to 5 cm. The measurements were performed at two moments in 2015 and 2018. The results indicated that the selective cut-by-diameter treatment had the lowest mortality rate and the highest recruitment rate. Predictions of the diameter structure using the Markov chain do not generally present statistical differences (α0.01) between the observed and expected frequencies for the year 2018. It was concluded that the basal area showed a tendency for recovery and growth in the treatments which involved suppression compared to the control, with no statistically significant differences among treatments until the moment after intervention.

RESUMO: O fracionamento químico de carbono (C) por um gradiente crescente de oxidação, tem se mostrado uma metodologia rápida e promissora para detectar alterações na labilidade de C. Os objetivos do presente estudo foram: avaliar o nível de labilidade do C orgânico do solo após a conversão de pastagens degradadas em leguminosas; avaliar a influência da profundidade do solo na labilidade do C orgânico do solo. A área experimental consistiu em plantios puros de Acacia auriculiformis, Mimosa caesalpiniifolia e Inga sp., uma pastagem e uma mata secundária. O carbono orgânico oxidável foi determinado por oxidação úmida e permitiu a separação de quatro frações de acordo com o nível de labilidade (lábil, moderadamente lábil, moderadamente recalcitrante, recalcitrante). A fração lábil foi a fração predominante em todas as coberturas vegetais e profundidades. A conversão de pastagens degradadas em leguminosas florestais e a profundidade do solo promoveram mudanças na composição química do C. A deposição contínua de resíduos vegetais por 13 anos de leguminosas favoreceu a distribuição das frações lábil e moderadamente lábil ao longo do perfil do solo e da fração recalcitrante na camada superficial do solo. As coberturas de referência contribuíram para a fração recalcitrante no solo abaixo de 20 cm de profundidade.

ABSTRACT: The chemical fractionation of C by an increasing oxidation gradient, has shown to be a fast and promising methodology to detect changes in C lability. The objectives of the present study presents were: to evaluate the level of lability of soil organic C after conversion of degraded pasture into leguminous trees; evaluate the influence of soil depth on the lability of soil organic C. The experimental area consisted of pure plantations of Acacia auriculiformis, Mimosa caesalpiniifolia and Inga sp., a pasture and a secondary forest. The oxidizable organic carbon was determined by wet oxidation and allowed separation of four fractions according to the lability level (labile, moderately labile, moderately recalcitrant, recalcitrant). Labile fraction was the predominant fraction in all vegetation covers and depths. The conversion of degraded pasture into forest legume plantations and the soil depth promoted changes in the chemical composition of C. The continuous deposition of vegetable residues 13 years of leguminous trees favored the distribution of labile and moderately labile fractions along the soil profile and the recalcitrant fraction in the topsoil. The reference covers contributed to the recalcitrant fraction in the soil below 20 cm depth.

Resumo O processo de decomposição da serapilheira regula o acúmulo de matéria orgânica no solo e a ciclagem de nutrientes, desempenhando importante papel na manutenção de ecossistemas florestais. Objetivou-se avaliar a decomposição da fração foliar da serapilheira de plantios homogêneos de Bambusa vulgaris, Azadirachta indica e de Eucalyptus urophylla, utilizando como referência uma área de Floresta Estacional Semidecidual. As áreas de estudo estão localizadas no município de Vitória da Conquista, Bahia, Brasil. Para a avaliação da decomposição utilizou-se o método dos litterbags, sendo as coletas realizadas aos 30, 75, 120, 180, 240 e 350 dias. A partir dos resultados de massa remanescente, estimou-se a constante de decomposição (k) e o tempo de meia-vida. A serapilheira foliar foi submetida à análises químicas para determinação dos teores de carbono, nitrogênio, polifenóis, celulose e lignina. Ao final de um ano, bambu e nim indiano tiveram mais de 65% da sua serapilheira decomposta, com constantes k iguais a 0,0033 e 0,0069 g g-1 dia, respectivamente. O plantio de eucalipto e a floresta nativa apresentaram perdas de massa inferiores a 50% e valores de k menores que 0,0020 g g-1 dia. A serapilheira foliar do bambu e do nim indiano mostra-se mais propensa à decomposição, com taxas superiores ao eucalipto e à floresta nativa, o que proporciona a estas duas espécies uma maior capacidade de reciclar matéria orgânica e nutrientes.

Abstract The litter decomposition process regulates the accumulation of organic matter in the soil and the cycling of nutrients, playing an important role in the forest ecosystems maintenance. The objective of this study was to evaluate the decomposition of the leaf fraction in the litter from homogeneous plantations of Bambusa vulgaris, Azadirachta indica, and Eucalyptus urophylla, using as reference an area of seasonal semi-deciduous forest. The study areas are located in the city of Vitória da Conquista, Bahia, Brazil. To evaluate the decomposition, we used the litterbags method, collecting specimens on days 30, 75, 120, 180, 240, and 350. From the results of the remaining mass, we estimated the decomposition constant (k) and the half-life time. The leaf litter was submitted to chemical analyses to determine the contents of carbon, nitrogen, polyphenols, cellulose, and lignin. By the end of one year, more than 65% of the litter from bamboo and Indian neem had decomposed with constants k equal to 0.0033 and 0.0069 g g-1 day, respectively. The Eucalyptus plantation and the native forest presented a mass loss lower than 50% and k values below 0.0020 g g-1 day. The leaf litter from bamboo and Indian neem is more prone to decomposition, with rates higher compared to eucalyptus and the native forest, which gives these two species a greater capacity to recycle organic matter and nutrients.

RESUMO O manejo florestal pode acarretar inúmeras modificações na composição e diversidade dos organismos do solo, em diferentes magnitudes de acordo com o nível de interferência no habitat. Neste contexto, o objetivo deste estudo foi testar a influência de diferentes tipos de manejo florestal sobre a comunidade da macrofauna edáfica em área de Caatinga arbórea. O estudo foi realizado na Floresta Nacional Contendas do Sincorá, Contendas do Sincorá - BA. A área experimental foi constituída de três tipos de manejo (corte raso, corte seletivo por diâmetro e corte seletivo por espécie) e uma condição de Caatinga não manejada, que foi utilizada como controle. A macrofauna foi amostrada pelo método do monólito de solo, em duas épocas do ano (março e novembro). Foram estimadas as densidades, o número total de indivíduos, a riqueza total, a riqueza média e os índices de Shannon e de Pielou. A macrofauna do solo mostrou-se sensível às diferentes práticas de manejo florestal, sendo indicativa de que os cortes seletivos são sistemas mais conservacionistas de uso da Caatinga. Dentre esses, o corte seletivo por espécie mostra-se menos impactante à macrofauna do solo, proporcionando índices de diversidade e abundância mais expressivos e a ocorrência de organismos mais exigentes em condições de microclima, característicos de áreas preservadas. Os grupos predominantes da fauna edáfica, tanto na Caatinga não manejada quanto na manejada, foram Isoptera, Formicidae, Larvas de Coleóptera e Chilopoda.

ABSTRACT Forest management can lead to numerous changes of different magnitudes in the composition and diversity of soil organisms, according to the level of interference with the habitat. Within this context, this study aimed to test the influence of different types of forest management on the edaphic macrofauna community in a region of arboreal Caatinga. The study was carried out in Contendas do Sincorá National Forest, Contendas do Sincorá - Bahia. The experimental area consisted of three types of management (clear cutting, selective cutting by diameter at breast height and selective cutting by species), and a condition of unmanaged Caatinga, which was used as control. The macrofauna was sampled twice a year (March and November) using the soil monolith method. Densities, total number of individuals, total richness, average richness, and Shannon and Pielou rates were estimated. The soil macrofauna was shown to be sensitive to different forest management practices, which indicates that selective cutting is a more conservative system to manage the Caatinga. Among these, selective cutting by species proved to be less impacting on the soil macrofauna, providing more expressive diversity and abundance indexes, and the occurrence of more demanding organisms in microclimate conditions, characteristic of preserved areas. The predominant groups of edaphic fauna, both in the unmanaged as in managed Caatinga, were Isoptera, Formicidae, Chilopoda, and Coleoptera Larvae.

ABSTRACT This work had the objective to evaluate the activity and microbial biomass of the soil as an indicator of edge effect in Semi-Deciduous Seasonal Forest fragments. Three fragments of different sizes (small, medium and large) located in the Southwest region of Bahia state were evaluated, in which three sampling ranges were defined in each, and soil samples were collected. The carbon and nitrogen contents of the microbial biomass were determined by the fumigation-extraction method and soil respiration. The microbial biomass carbon (MBC), metabolic carbon quotient (qCO2) and the microbial C:N and MBC:C ratios were discriminating indicators of the edge effect on the soil quality of the studied forest fragments. The integrated analysis of soil microbiological attributes is adequate to evaluate the edge effect in forest fragments. The size of the fragments and their isolation influence the MBC contents, showing greater vulnerability of the smaller fragments in relation to the actions of the external environment.

ABSTRACT The edge effect makes forest communities more susceptible to changes and may cause changes in different ecosystem characteristics such as litter production. The objective of this work was to evaluate the edge effect on the contribution of litter and its temporal variation in a Semi-Deciduous Seasonal Forest fragment located in Vitória da Conquista, BA, Brazil. Four sampling ranges were delimited in the forest fragment: edge (0-10 m from the edge), transition 1 (40-50 m from the edge), transition 2 (80-90 m from the edge) and interior (400-410 m from the edge). The produced litter was collected monthly. The main litter components were leaves and branches in all sampling ranges. The contribution of the other fractions obeyed different orders at the edges (bark > reproductive structures) and interior (reproductive structures > bark). The edge effect did not influence the contribution of total litter and its temporal variation, only manifesting in the production of reproductive structures.

RESUMO A magnitude das alterações em atributos do solo pode ser utilizada para identificar efeitos de interferências naturais ou antrópicas em fragmentos florestais. Este trabalho objetivou avaliar atributos químicos do solo como indicadores de efeito de borda em fragmento de Floresta Estacional Semidecidual, no Sudoeste da Bahia. Foram definidas quatro faixas de amostragem no fragmento florestal (Faixa 1: 0-10m, Faixa 2: 40-50 m, Faixa 3: 80-90 m e Faixa 4: 400-410 m da borda). Uma área de pastagem nativa degradada foi utilizada como referência. Foram coletadas amostras de solo nas profundidades 0-5, 5-10 e 10-20 cm. As amostras foram submetidas a análises para determinação do pH e dos teores de matéria orgânica, P, K, Ca, Mg e Al. A camada superficial do solo mostrou-se sensível às variações impostas pela fragmentação, refletindo modificações em alguns dos seus atributos químicos até uma distância de 90 m da borda em direção ao interior do fragmento, com efeitos mais severos nos primeiros 10 metros. Matéria orgânica do solo, acidez potencial, CTC e pH foram os atributos mais afetados, evidenciando um gradiente de variação no sentido borda-interior.

ABSTRACT The magnitude of changes in soil attributes can be used to identify the effects of natural or anthropogenic interference on forest fragments. The objective of this work was to evaluate the chemical attributes of the soil as indicators of the edge effect at a Seasonal Semi-deciduous Forest fragment in the Southwest of Bahia, Brazil. Four sampling ranges were defined in the forest fragment (Range 1: 0-10m; Range 2: 40-50 m; Range 3: 80-90 m; and Range 4: 400-410 m from the edge). A degraded native pasture area was used as the reference. Soil samples were collected at depths of 0-5, 5-10 and 10-20 cm. The samples were analyzed for pH and organic matter, P, K, Ca, Mg and Al. The superficial layer of the soil was sensitive to the changes imposed by the fragmentation, reflecting modifications in some of its chemical attributes up to a distance of 90 m from the edge towards the interior of the fragment, with more severe effects in the first 10 meters. Soil organic matter, potential acidity, CEC and pH were the most affected attributes, evidencing a gradient of variation in the edge-interior direction.

ABSTRACT The aim of this study was to evaluate the edge effect using the macrofauna community of the soil as indicator in three fragments of Semi-deciduous Seasonal Forest in the city of Vitória da Conquista, Bahia, Brazil. Three sampling ranges denominated edge, transition and interior were delimited in each fragment. The macrofauna community was sampled at two seasons of the year (dry and wet). Monoliths were collected from soil at 10 cm depth in each range. The density and richness of the fauna, as well as the Shannon diversity index and the Pielou equitability index, were calculated. It was observed that the edge effect is expressed from the presence/absence of orders of individuals in the different fragment ranges, with no interference in the density, average wealth or number of individuals in each group. The edaphic community presents higher density and average richness in the dry period within the transition and interior range of the fragments.

ABSTRACT Litter production and decomposition makes it possible to supply a good part of the nutrient demand of forest stands. Although several studies on this subject have been carried out in Pinus stands in different regions of Brazil, there are no records of studies carried out in the Northeast region, or in particular in the state of Bahia. Therefore, the objective of this work was to evaluate the litter production (litterfall) and decomposition in Pinus stands in the southwest region of Bahia, using an area of native forest as reference. Litterfall was evaluated during twelve months with the use of suspended collectors. Litter accumulation was quantified by means of three collections. The values obtained from litterfall were similar among Pinus stands. However, these values were lower than those found in the reference forest and in stands of the same genus in other regions of Brazil. Litter decomposition is relatively slow in Pinus sp. stands. The temporal variation of the litter supply is not very sensitive to the climate variations.

ABSTRACT Carbon binding capacity varies between forest plantations, mainly in terms of species and climate and soil conditions. The objective of this study was to estimate the amount of organic carbon stored in aerial tree biomass in the litter and soil of a homogeneous planting of Pterogyne nitens Tul. located in the Southwest Bahia region of Brazil. The woody biomass was obtained by destructive method. Litter collection was carried out using a wooden template (0.25 m2). Soil samples were collected at four depths (0-5, 5-10, 10-20 and 20-40 cm). The carbon stored in all studied compartments totaled 47.1 Mg ha-1 with a greater contribution from the ground (31.4 t ha-1). The accumulated litter was the lowest carbon compartment, storing about 1.4% of the total. Among the different fractions of the biomass, the stem is the largest carbon reservoir, representing about 46% of fixed C biomass.

RESUMO A estratificação vertical, bem como vários parâmetros ecológicos de suma importância para a estrutura fitossociológica em florestas inequiâneas, reflete a quantidade de energia existente na floresta. O presente trabalho teve como objetivo avaliar o desempenho das metodologias usuais de caracterização da estratificação vertical em florestas. O levantamento de dados foi realizado em um fragmento de Floresta Estacional, no município de Vitória da Conquista, no campus da Universidade Estadual do Sudoeste da Bahia. A Posição Sociológica foi considerada como método padrão neste estudo. Os resultados obtidos foram comparados com outros seis diferentes métodos: IUFRO, Vega, Longhi, Calegário, Souza e Leite e Hasenauer. O desempenho dos métodos foi avaliado segundo o coeficiente “c”. Foram classificados pelo método padrão 954 indivíduos obtendo os seguintes resultados: 656 dominantes, 232 codominantes e 66 dominados. O coeficiente “c” mostrou-se eficiente na interpretação do desempenho dos métodos. O método da IUFRO apresentou o melhor desempenho em comparação ao Método da Posição Sociológica.

ABSTRACT Vertical stratification - as well as other environmental phytosociological parameters for uneven-aged stands in forest structures - is one of the factors that regulates the amount of energy present in a forest, although it is often disregarded. The objective of this study is to evaluate the performance of some commonly used methodologies to characterize the vertical stratification of a forest fragment. Researchers from UESB - State University of Southwest Bahia collected data in a Seasonal Forest fragment located in the city of Vitória da Conquista, Bahia, Brazil. The standard method used in the study was the Sociological Position Method. Results were compared to six other methods: IUFRO; Vega; Longhi; Calegário; Souza and Leite; and Hasenauer. The performance of each method was assessed according to the “c” coefficient. Results of the standard method showed 954 individuals (656 dominant; 232 codominant; and 66 dominated). The “c” coefficient was found to be efficient to interpret the performance of these methods. The IUFRO Method showed the best performance when compared to the Sociological Position Methods.

ABSTRACT The present study was carried out with the objective of evaluating the field performance of six Eucalyptus clones, using seed-produced Eucalyptus urophylla as a reference. The experiment was conducted in the city of Vitória da Conquista, Bahia, Brazil. The plants were monitored monthly with diameter at ground level and height measurements taken up to nine months after planting. Diameter at breast height (DBH) and height measurements, as well as the biomass of all tree components and stem volumes were obtained 12 months after planting. VM058 and I-144 were the only clones that showed survival rates below 70%. Nevertheless, up to the age of 12 months and similar to the seed-produced E. urophylla , the VM058 clone was the genetic material that presented the most satisfactory production given the edaphoclimatic conditions of Vitória da Conquista, Bahia, Brazil.