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de Lacerda A.E.B.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria | Nimmo E.R.,University of Sao Paulo | Sebbenn A.M.,Instituto Florestal Of Sao Paulo
Forest Science | Year: 2013

Although selective logging is a common practice for timber production in the Brazilian Amazon, very little is known about its impacts on genetic diversity and demography of the harvested species. This study explores the sustainability of current forest management systems in the Brazilian Amazon by modeling harvesting cycles and examining the impacts on the genetic diversity and demography of the highly valued species Hymenaea courbaril. Using extensive field data, we introduced a two-step modeling procedure for EcoGene software that allowed us to identify optimal felling cycles that were later used for testing and defining sustainable logging parameters. The results show that logging cycles for H. courbaril should be approximately of 110 years, as opposed to the 30-year cycle currently used in Brazil, and harvesting levels should consider a combination of larger minimum cutting diameters (75-100 cm) and lower logging intensities (10-50%). We conclude that current practices in Brazil (30-year cycle, logging intensities of 90%, and minimum cutting diameters of 50 cm) are unsustainable for H. courbaril and that the current practice of using general logging prescriptions for all species does not deliver sustainable forest management in the Amazon. Brazilian forest harvesting regulations need to move toward species-specific prescriptions to ensure real sustainability in the long term. © 2013 by the Society of American Foresters.

de Bressan E.A.,University of Sao Paulo | Scotton D.C.,University of Sao Paulo | Ferreira R.R.,University of Sao Paulo | Jorge E.C.,Federal University of Minas Gerais | And 3 more authors.
American Journal of Botany | Year: 2012

Premise of the study: Microsatellite primers were developed for Jatropha curcas (Euphorbiaceae), a tree species with large potential for biofuel production, to investigate its natural genetic diversity and mating system to facilitate the establishment of tree improvement and conservation programs. Methods and Results: Using a protocol for genomic library enrichment, 104 clones containing 195 repeat motifs were identify ed. Primer pairs were developed for 40 microsatellite loci and validated in 41 accessions of J. curcas from six provenances. Nine loci were polymorphic revealing from two to eight alleles per locus, and six primers were able to amplify alleles in the congeners J. podagrica, J. pohliana, and J. gossypifolia, but not in other Euphorbiaceae species, such as Hevea brasiliensis, Manihot esculenta, or Ricinus communis. Conclusions: The primers developed here revealed polymorphic loci that are suitable for genetic diversity and structure, mating system, and gene flow studies in J. curcas, and some congeners. © 2012 Botanical Society of America.

Tarazi R.,University of Sao Paulo | Sebbenn A.M.,Instituto Florestal Of Sao Paulo | Kageyama P.Y.,University of Sao Paulo | Vencovsky R.,University of Sao Paulo
Ecology and Evolution | Year: 2013

Savannas are highly diverse and dynamic environments that can shift to forest formations due to protection policies. Long-distance dispersal may shape the genetic structure of these new closed forest formations. We analyzed eight microsatellite loci using a single-time approach to understand contemporary pollen and effective seed dispersal of the tropical tree, Copaifera langsdorffii Desf. (Fabaceae), occurring in a Brazilian fire- and livestock-protected savanna. We sampled all adult trees found within a 10.24 ha permanent plot, young trees within a subplot of 1.44 ha and open-pollinated seeds. We detected a very high level of genetic diversity among the three generations in the studied plot. Parentage analysis revealed high pollen immigration rate (0.64) and a mean contemporary pollen dispersal distance of 74 m. In addition, half-sib production was 1.8 times higher than full-sibs in significant higher distances, indicating foraging activity preference for different trees at long distances. There was a significant and negative correlation between diameter at breast height (DBH) of the pollen donor with the number of seeds (r = -0.640, P-value = 0.032), suggesting that pollen donor trees with a higher DBH produce less seeds. The mean distance of realized seed dispersal (recruitment kernel) was 135 m due to the large home range dispersers (birds and mammals) in the area. The small magnitude of spatial genetic structure found in young trees may be a consequence of overlapping seed shadows and increased tree density. Our results show the positive side of closed canopy expansion, where animal activities regarding pollination and seed dispersal are extremely high.© 2013 The Authors. Ecology and Evolution.

Cupressus lusitanica has a relatively low potential for fostering colonization of native species beneath the forest canopy. However, following the clearcut of a Cupressus lusitanica plantation in the State Forest of Avaré (SFA), southeastern Brazil, a vigorous regeneration of Atlantic forest tree and shrub species was observed. We evaluated the passive restoration of this site by comparing its regenerating vegetation to the vegetation established in man-made gaps in Atlantic forest in the State Park of Cantareira (SPC), southeastern Brazil. The frequency distribution of dispersal syndromes for species and the rate of reduction in abundance of pioneer species in a rank/abundance plot did not differ between the two areas. The rarefaction curves for species richness and diversity of the SPC fall below the corresponding curves of the SFA. The proportions of non-pioneer species and of individuals of non-pioneer species were greater in the SFA. The frequency distribution of dispersal syndromes for individuals differed between the two areas due mainly to a more conspicuous predominance of zoochory in the SFA. The rate of reduction in abundance of non-pioneer species in a rank/abundance plot was smaller in the SFA. We concluded that passive restoration may successfully recover native vegetation attributes following the clearcut of forest plantations without conspicuous regeneration of native species beneath the forest canopy. However, this phenomenon may be influenced by particular properties of the forest species, logging practices and faunal seed dispersal integrity. © 2016, Universidade Federal de Santa Maria. All Rights Reserved.

Feres J.M.,University of Sao Paulo | Sebbenn A.M.,Instituto Florestal Of Sao Paulo | Guidugli M.C.,University of Sao Paulo | Mestriner M.A.,University of Sao Paulo | And 2 more authors.
Conservation Genetics | Year: 2012

For many tree species, mating system analyses have indicated potential variations in the selfing rate and paternity correlation among fruits within individuals, among individuals within populations, among populations, and from one flowering event to another. In this study, we used eight microsatellite markers to investigate mating systems at two hierarchical levels (fruits within individuals and individuals within populations) for the insect pollinated Neotropical tree Tabebuia roseo-alba. We found that T. roseo-alba has a mixed mating system with predominantly outcrossed mating. The outcrossing rates at the population level were similar across two T. roseo-alba populations; however, the rates varied considerably among individuals within populations. The correlated paternity results at different hierarchical levels showed that there is a high probability of shared paternal parentage when comparing seeds within fruits and among fruits within plants and full-sibs occur in much higher proportion within fruits than among fruits. Significant levels of fixation index were found in both populations and biparental inbreeding is believed to be the main cause of the observed inbreeding. The number of pollen donors contributing to mating was low. Furthermore, open-pollinated seeds varied according to relatedness, including half-sibs, full-sibs, self-sibs and self-half-sibs. In both populations, the effective population size within a family (seed-tree and its offspring) was lower than expected for panmictic populations. Thus, seeds for ex situ conservation genetics, progeny tests and reforestation must be collected from a large number of seed-trees to guarantee an adequate effective population in the sample. © 2011 Springer Science+Business Media B.V.

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