Management of lianas in semideciduous forest and cerradão edges, Santa Rita do Passa Quatro, SP

No Estado de São Paulo, dentro de uma mesma zona climática, a floresta estacional semidecidual e o cerradão são comumente encontrados dividindo o espaço. Atualmente, essas duas formações encontram-se reduzidas a pequenos fragmentos florestais, em estágio avançado de perturbação. Com a fragmentação da floresta, há um aumento da luminosidade nas bordas dos remanescentes florestais e lianas heliófitas podem aumentar suas populações e competir vigorosamente com as espécies arbustivo-arbóreas. O objetivo desse estudo foi verificar o efeito do manejo das lianas sobre o processo de restauração florestal em bordas perturbadas de floresta estacional semidecidual e de cerradão. Também foi analisada a influência do tipo de vizinhança sobre a borda florestal e sobre os resultados do manejo. O experimento foi instalado na região de Santa Rita do Passa Quatro, SP, em bordas de floresta estacional semidecidual, com vizinhanças de cana-de-açúcar e rodovia e em bordas de cerradão, com vizinhanças de eucalipto, cana-deaçúcar e rodovia. O delineamento experimental foi de blocos casualizados, com parcelas de 100m2 e 3 repetições. Nas bordas de floresta estacional semidecidual foram testadas 3 técnicas de manejo: corte de lianas (C), corte de lianas + revolvimento do solo (CR) e corte de lianas + plantio de espécies arbóreas nativas (CP). Nas bordas de cerradão foram testadas 2 técnicas de manejo: corte de lianas (C) e corte de lianas + revolvimento do solo (CR). Para análise do processo de restauração florestal, foram avaliados o crescimento médio em altura e diâmetro das espécies arbustivoarbóreas, a mortalidade média e o número médio de indivíduos ingressantes no estrato arbustivoarbóreo, a chuva de sementes e a mortalidade média e o número médio de indivíduos ingressantes no estrato da regeneração. Nas duas formações florestais, verificou-se uma diminuição na riqueza de espécies arbustivo-arbóreas e no número de árvores de maior porte, no sentido das bordas com vizinhança de eucalipto, para as bordas com vizinhanças de cana-de-açúcar e rodovia, respectivamente. Tanto nas bordas de floresta estacional semidecidual, quanto de cerradão, os resultados do manejo das lianas foram influenciados pelo grau de infestação por lianas, pela estrutura da vegetação recém manejada, pelas espécies presentes e pela vizinhança do fragmento florestal. Embora na maioria dos casos as diferenças não tenham sido significativas, efeitos positivos do corte das lianas foram observados para o crescimento médio em altura ou diâmetro dos indivíduos, principalmente nas áreas mais infestadas. No entanto, nas bordas com vizinhança de rodovia, o corte das lianas pode intensificar os efeitos de borda, a ponto de prejudicar o ingresso das espécies arbustivo-arbóreas no estrato da regeneração. Nas bordas de floresta estacional semidecidual, o corte das lianas não será suficiente para promover a recuperação da fisionomia florestal, pois os indivíduos presentes sob as lianas correspondem a espécies de subbosque, sendo necessário o enriquecimento das bordas com espécies de dossel. Nas duas formações florestais, o revolvimento superficial do solo não favoreceu a regeneração das espécies arbustivo-arbóreas.In São Paulo state, throughout the same climatic zone, semideciduous forests and cerradão patches commonly share the same geographic area. Currently, these two formations are reduced to small fragments, in advanced stage of disturbance. Along with the fragmentation of the forest, there is an increase in ligth incidence at the edges and lianas generally increase their populations, competing vigorously with trees and shrubs species. The objective of this study was to verify the effect of management of lianas on the processe of restoration of forest physionomy in disturbed edges of semideciduous forest and cerradão. It was also analyzed the influence of matrix on the edge of forests and the results of liana removal management. The experiment was installed in Santa Rita do Passa Quatro, SP, on the edges of semideciduous forest fragments surrounded by sugar cane and roads, and cerradão fragments bordered by eucalyptus plantations, sugar cane and roads. The experimental design was randomized with blocks of plots of 100m2 and 3 replications. At the edges of semideciduous forest three techniques of management were tested: cutting of lianas (C), cutting of lianas + revolving surface soil (CR) and cutting of lianas + planting of native tree species (CP). On the edges of cerradão two management alternatives were tested: cutting of lianas (C) and cutting of lianas + revolving surface soil (CR). To analyze the process of restoration of forest physionomy, we assessed the average growth in height and diameter of tree and shrub species, the average mortality and average number of individuals entering the tree stratum, the rain seed, the average mortality and the average number of individuals entering the stratum of regeneration. In both forests, there was a decrease in the richness of tree and shrub species and the number of larger trees from areas surrounded by eucalyptus to areas in a matrix of sugar cane and road. The results of lianas management, both on semideciduous forest and cerradão, were influenced by the degree of infestation, by the structure of vegetation recently managed, by the species composition and by the nature of surrounding matrix. Although in most cases the differences were not significant, positive effects of cutting lianas were observed on the average growth in height or diameter of the individual, mainly in the most infested areas. However, when the edges are contiguous to roads, lianas removal may intensify edge effects, as to disturb the number of individuals entering the stratum of regeneration. On semideciduous forests, cutting the lianas on the edges alone will not be enough to promote the recovery of the forest structure, because individuals providing support for lianas are understory species, being necessary the enrichment of the edges with the tree canopy species. In both forests, the revolving surface soil did not favor the regeneration of arbustive-arboreal species

REPEATABILITY OF FRUITS AND SEEDS PRODUCTION AND SELECTION OF BRAZIL NUT GENOTYPES IN NATIVE POPULATIONS IN RORAIMA1

ABSTRACT This study estimates the repeatability coefficients of two production traits in two native populations of Brazil nut trees. It determines the number of years of suitable evaluations for an efficient selection process, determines the permanent phenotypic correlation between production traits and also the selection of promising trees in these populations. Populations, located in the Itã region (ITA) and in the in the Cujubim region (CUJ), are both belonging to the municipality of Caracaraí, state of Roraima - Brazil, and consist of 85 and 51 adult trees, respectively. Each tree was evaluated regarding the number of fruits per plant (NFP) and fresh seed weight per plant (SWP), for eight (ITA) and five consecutive years (CUJ). Statistical analyses were performed according to the mixed model methodology, using Software Selegen-REML/BLUP (RESENDE, 2007). The repeatability coefficients were low for NFP (0.3145 and 0.3269 for ITA and CUJ, respectively) and also for SWP (0.2957 and 0.3436 for ITA and CUJ, respectively). It on average takes nine evaluation years to reach coefficients of determination higher than 80%. Permanent phenotypic correlation values higher than 0.95 were obtained for NFP and SWP in both populations. Although trees with a high number of fruits and seed weight were identified, more evaluation years are needed to perform the selection process more efficiently