Linking above and belowground carbon sequestration, soil organic matter properties, and soil health in Brazilian Atlantic Forest restoration.

Forest restoration mitigates climate change by removing CO2 and storing C in terrestrial ecosystems. However, incomplete information on C storage in restored tropical forests often fails to capture the ecosystem's holistic C dynamics. This study provides an integrated assessment of C storage in above to belowground subsystems, its consequences for greenhouse gas (GHG) fluxes, and the quantity, quality, and origin of soil organic matter (SOM) in restored Atlantic forests in Brazil. Relations between SOM properties and soil health indicators were also explored. We examined two restorations using tree planting ('active restoration'): an 8-year-old forest with green manure and native trees planted in two rounds, and a 15-year-old forest with native-planted trees in one round without green manure. Restorations were compared to reformed pasture and primary forest sites. We measured C storage in soil layers (0-10, 10-20, and 20-30 cm), litter, and plants. GHG emissions were assessed using CH4 and CO2 fluxes. SOM quantity was evaluated using C and N, quality using humification index (HLIFS), and origin using δ13C and δ15N. Nine soil health indicators were interrelated with SOM attributes. The primary forest presented the highest C stocks (107.7 Mg C ha-1), followed by 15- and 8-year-old restorations and pasture with 69.8, 55.5, and 41.8 Mg C ha-1, respectively. Soil C stocks from restorations and pasture were 20% lower than primary forest. However, 8- and 15-year-old restorations stored 12.3 and 28.3 Mg ha-1 more aboveground C than pasture. The younger forest had δ13C and δ15N values of 2.1 and 1.7‰, respectively, lower than the 15-year-old forest, indicating more C derived from C3 plants and biological N fixation. Both restorations and pasture had at least 34% higher HLIFS in deeper soil layers (10-30 cm) than primary forest, indicating a lack of labile SOM. Native and 15-year-old forests exhibited higher soil methane influx (141.1 and 61.9 µg m-2 h-1). Forests outperformed pasture in most soil health indicators, with 69% of their variance explained by SOM properties. However, SOM quantity and quality regeneration in both restorations approached the pristine forest state only in the top 10 cm layer, while deeper soil retained agricultural degradation legacies. In conclusion, active restoration of the Atlantic Forest is a superior approach compared to pasture reform for GHG mitigation. Nonetheless, the development of restoration techniques to facilitate labile C input into deeper soil layers (>10 cm) is needed to further improve soil multifunctionality and long-term C storage.

Can plant DNA barcoding be implemented in species-rich tropical regions? A perspective from São Paulo State, Brazil.

DNA barcoding helps to identify species, especially when identification is based on parts of organisms or life stages such as seeds, pollen, wood, roots or juveniles. However, the implementation of this approach strongly depends on the existence of complete reference libraries of DNA sequences. If such a library is incomplete, DNA-based identification will be inefficient. Here, we assess if DNA barcoding can already be implemented in species-rich tropical regions. We focus on the tree flora of São Paulo state, Brazil, which contains more than 2000 tree species. Using new DNA sequence data and carefully assembled GenBank accessions, we assembled 12,113 sequences from ten different regions. The ITS, rbcL, psbA-trnH, matK and trnL regions were better represented within the available sequences for São Paulo tree flora. Currently, only 58% of the São Paulo tree flora currently have at least one barcoding sequence available. However, these species represent on average 89% of the trees in São Paulo state forests. Therefore, conservation-oriented and ecological studies can already benefit from DNA barcoding to obtain more accurate species identifications. We present which taxa remain underrepresented for the São Paulo tree flora and discuss the implications of this result for other species-rich tropical regions.

Forest restoration rehabilitates soil multifunctionality in riparian zones of sugarcane production landscapes.

Brazilian sugarcane plays a vital role in the production of both sugar and renewable energy. However, land use change and long-term conventional sugarcane cultivation have degraded entire watersheds, including a substantial loss of soil multifunctionality. In our study, riparian zones have been reforested to mitigate these impacts, protect aquatic ecosystems, and restore ecological corridors within the sugarcane production landscapes. We examined (i) how forest restoration enables rehabilitation of the soil's multifunctionality after long-term sugarcane cultivation and (ii) how long it takes to regain ecosystem functions comparable to those of a primary forest. We investigated a time series of riparian forests at 6, 15, and 30 years after starting restoration by planting trees (named 'active restoration') and determined soil C stocks, δ13C (indicative of C origin), as well as measures indicative of soil health. A primary forest and a long-term sugarcane field were used as references. Eleven soil physical, chemical, and biological indicators were used for a structured soil health assessment, calculating index scores based on soil functions. Forest-to-cane conversion reduced 30.6 Mg ha-1 of soil C stocks, causing soil compaction and loss of cation exchange capacity, thus degrading soil's physical, chemical, and biological functions. Forest restoration for 6-30 years recovered 16-20 Mg C ha-1 stored in soils. In all restored sites, soil functions such as supporting root growth, aerating the soil, nutrient storage capacity, and providing C energy for microbial activity were gradually recovered. Thirty years of active restoration was sufficient to reach the primary forest state in overall soil health index, multifunctional performance, and C sequestration. We conclude that active forest restoration in sugarcane-dominated landscapes is an effective way to restore soil multifunctionality approaching the level of the native forest in approximately three decades. Moreover, the C sequestration in the restored forest soils will help to mediate global warming.

Biodiversity responses to restoration across the Brazilian Atlantic Forest.

The UN Decade on Ecosystem Restoration is focussing attention and resources on restoration globally. Nowhere is this more crucial than in tropical forests that harbor immense biodiversity, but have also undergone widespread deforestation over the past few decades. We performed a meta-analysis to investigate how biodiversity features respond to forest restoration across the Brazilian Atlantic Forest (BAF), one of the most threatened biodiversity hotspots in the world. We assembled biodiversity in different metrics of structure and diversity features of three taxonomic groups (vascular plants, soil microorganisms, and invertebrates), generating a dataset with 2370 observations from 76 primary studies. We quantified the incomplete recovery of biodiversity (i.e., the rate of recovery to a pre-disturbance state) occurring during the restoration process, which we called the 'recovery gap'. Our results revealed that forests undergoing restoration in the BAF show a recovery gap of 34% for structure features and 22% for diversity features in comparison to reference reforests, considering all taxonomic groups investigated. For vascular plants, soil microorganisms, and invertebrates the recovery gap ranged between 46 and 47%, 16-26%, and 4-7%, respectively. Overall, the recovery gap was influenced by the interaction of restoration actions (i.e., the past land use, restoration age and restoration approach - active and passive restoration), however, structure features responded more sensitively to the time elapsed since restoration started, while the recovery gap for diversity features depended more on the past land-use. Our study can help guide the prioritization of the aforenamed taxonomic groups in restoration, the regulation of potential biodiversity offsetting policies in the BAF, and understanding how coupled biodiversity features respond to the interaction of environmental conditions and restoration actions in a high fragmented tropical landscape.

Author Correction: Strategic approaches to restoring ecosystems can triple conservation gains and halve costs.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Strategic approaches to restoring ecosystems can triple conservation gains and halve costs.

International commitments for ecosystem restoration add up to one-quarter of the world's arable land. Fulfilling them would ease global challenges such as climate change and biodiversity decline but could displace food production and impose financial costs on farmers. Here, we present a restoration prioritization approach capable of revealing these synergies and trade-offs, incorporating ecological and economic efficiencies of scale and modelling specific policy options. Using an actual large-scale restoration target of the Atlantic Forest hotspot, we show that our approach can deliver an eightfold increase in cost-effectiveness for biodiversity conservation compared with a baseline of non-systematic restoration. A compromise solution avoids 26% of the biome's current extinction debt of 2,864 plant and animal species (an increase of 257% compared with the baseline). Moreover, this solution sequesters 1 billion tonnes of CO2-equivalent (a 105% increase) while reducing costs by US$28 billion (a 57% decrease). Seizing similar opportunities elsewhere would offer substantial contributions to some of the greatest challenges for humankind.

Genomic diversity is similar between Atlantic Forest restorations and natural remnants for the native tree Casearia sylvestris Sw.

The primary focus of tropical forest restoration has been the recovery of forest structure and tree taxonomic diversity, with limited attention given to genetic conservation. Populations reintroduced through restoration plantings may have low genetic diversity and be genetically structured due to founder effects and genetic drift, which limit the potential of restoration to recover ecologically resilient plant communities. Here, we studied the genetic diversity, genetic structure and differentiation using single nucleotide polymorphisms (SNP) markers between restored and natural populations of the native tree Casearia sylvestris in the Atlantic Forest of Brazil. We sampled leaves from approximately 24 adult individuals in each of the study sites: two restoration plantations (27 and 62 years old) and two forest remnants. We prepared and sequenced a genotyping-by-sequencing library, SNP markers were identified de novo using Stacks pipeline, and genetic parameters and structure analyses were then estimated for populations. The sequencing step was successful for 80 sampled individuals. Neutral genetic diversity was similar among restored and natural populations (AR = 1.72 ± 0.005; HO = 0.135 ± 0.005; HE = 0.167 ± 0.005; FIS = 0.16 ± 0.022), which were not genetically structured by population subdivision. In spite of this absence of genetic structure by population we found genetic structure within populations but even so there is not spatial genetic structure in any population studied. Less than 1% of the neutral alleles were exclusive to a population. In general, contrary to our expectations, restoration plantations were then effective for conserving tree genetic diversity in human-modified tropical landscapes. Furthermore, we demonstrate that genotyping-by-sequencing can be a useful tool in restoration genetics.

Science and environmental policy establishment: the case of the Forest Act in the State of São Paulo, Brazil / Ciência e implementação de política ambiental: o caso do Código Florestal no Estado de São Paulo, Brasil

Abstract Natural ecosystems are under severe threat worldwide and environmental policies are essential to minimize present and future impacts on biodiversity, ecosystem services and climate change. The New Forest Act in Brazil is the main policy to protect native vegetation in private lands, which comprise 54% of the remaining Brazilian native vegetation. However, conflicts between environmental and agricultural concerns in its implementation demand for balanced solutions based on scientific evidence. To face the challenge of applying science in environmental policy establishment, we developed a scientific project funded by the São Paulo State Research Foundation (FAPESP) to support the implementation of the New Forest Act in São Paulo State, as part of the Biota/FAPESP Program. The project was conducted differently from a regular research project: the broad objective was to provide scientific support to the State's implementation of the New Forest Act, based on a participatory interaction among stakeholders to build specific objectives, methods, and discussion of results, within an interdisciplinary and intersectoral research team. Here, we present the lessons learned during and after the four years of the research project development to evaluate how scientific knowledge can be produced and adopted in the implementation of a specific environmental policy. We present the main outcomes and the challenges faced in trying to include scientific data in the decision-making process. We also present current and future challenges in the New Forest Act implementation that could be solved with scientific evidence. The lessons learned showed that even designing the project in order to meet the needs to support the implementation of the environmental policy, avoiding difficulties normally pointed out by similar projects, there was a great difficulty for scientific contributions to be adopted in the decision-making process. Most of the scientific information and advice, even after discussion and common understanding among a diverse stakeholder group, were ignored or over-ruled in the final decision-making phases.

Resumo Os ecossistemas naturais estão sob grave ameaça em todo o mundo e as políticas ambientais são essenciais para minimizar os impactos presentes e futuros na biodiversidade, nos serviços ecossistêmicos e nas mudanças climáticas. O Novo Código Florestal no Brasil é a principal política de proteção da vegetação nativa em terras privadas, que compreende 54% da vegetação nativa remanescente brasileira. No entanto, os conflitos entre as preocupações ambientais e agrícolas na sua implementação exigem soluções equilibradas e baseadas em evidências científicas. Para enfrentar o desafio de aplicar a ciência no estabelecimento de políticas ambientais, desenvolvemos um projeto científico financiado pela Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) para apoiar a implementação do Novo Código Florestal no Estado de São Paulo, como parte do Programa Biota/FAPESP. O projeto foi conduzido de forma diferente de um projeto de pesquisa regular: o objetivo amplo foi fornecer suporte científico para a implementação do Novo Código Florestal pelo Estado, a partir de uma interação participativa entre as partes interessadas para construir objetivos específicos, métodos e discussão de resultados, dentro de uma equipe de pesquisa interdisciplinar e intersetorial. Aqui, apresentamos as lições aprendidas durante e após os quatro anos de desenvolvimento do projeto de pesquisa para avaliar como o conhecimento científico pode ser produzido e adotado na implementação de uma política ambiental específica. Apresentamos os principais resultados e os desafios enfrentados na tentativa de incluir dados científicos no processo decisório. Apresentamos também desafios atuais e futuros na implementação do Novo Código Florestal que podem ser resolvidos com evidências científicas. As lições aprendidas mostraram que mesmo concebendo o projeto de forma a atender as necessidades de apoio à implementação da política ambiental, evitando dificuldades normalmente apontadas por projetos semelhantes, houve uma grande dificuldade para que contribuições científicas fossem adotadas no processo decisório. A maioria das informações e conselhos científicos, mesmo após discussão e entendimento comum entre um grupo diversificado de partes interessadas, foi ignorada nas fases finais de tomada de decisão.

Community-wide spatial and temporal discordances of seed-seedling shadows in a tropical rainforest.

Several factors decrease plant survival throughout their lifecycles. Among them, seed dispersal limitation may play a major role by resulting in highly aggregated (contagious) seed and seedling distributions entailing increased mortality. The arrival of seeds, furthermore, may not match suitable environments for seed survival and, consequently, for seedling establishment. In this study, we investigated spatio-temporal patterns of seed and seedling distribution in contrasting microhabitats (bamboo and non-bamboo stands) from the Brazilian Atlantic Forest. Spatial distribution patterns, spatial concordance between seed rain and seedling recruitment between subsequent years in two fruiting seasons (2004-2005 and 2007-2009), and the relation between seeds and seedlings with environmental factors were examined within a spatially-explicit framework. Density and species richness of both seeds and seedlings were randomly distributed in non-bamboo stands, but showed significant clustering in bamboo stands. Seed and seedling distributions showed across-year inconsistency, suggesting a marked spatial decoupling of the seed and seedling stages. Generalized linear mixed effects models indicated that only seed density and seed species richness differed between stand types while accounting for variation in soil characteristics. Our analyses provide evidence of marked recruitment limitation as a result of the interplay between biotic and abiotic factors. Because bamboo stands promote heterogeneity in the forest, they are important components of the landscape. However, at high densities, bamboos may limit recruitment for the plant community by imposing marked discordances of seed arrival and early seedling recruitment.

Unfolding additional massive cutback effects of the Native Vegetation Protection Law on Legal Reserves, Brazil / Revelando reduções adicionais de Reserva Legal da Lei de Proteção da Vegetação Nativa, Brasil

Abstract: The Native Vegetation Protection Law - 2012 - (NVPL) is the main Brazilian regulation for protecting native vegetation (NV) on private land. The NVPL, currently in the implementation phase, reduced Legal Reserves (LR) requirements compared to its previous version, the 1965's Forest Act (FA), through several legal mechanisms. Among them, Article 68 (Art.68) exempts landholders from LR obligations if NV was converted without offending the legislation in place at the time of the conversion. The technical implementation of Art. 68 is controversial and its effects are still unknown. We developed a model to estimate the effects of Art.68 on LR using São Paulo State (Brazil) as case study. We analyzed former environmental laws to identify key periods in which NV preservation requirements had changed. After, we searched for past spatial data on NV cover with sufficient accuracy for each legal benchmark. Combining legal benchmarks with spatial data, we created two scenarios for Art.68 effects, plus a baseline scenario. The first scenario considered a single legal benchmark, the 1965's FA (scenario "1965"), while the other included the 1989 Cerrado's protection Federal Law as a second benchmark (scenario "1965/89"). The baseline scenario did not include Art.68 effects. Scenario "1965" reduced LR deficits in 49% compared to the baseline scenario, waiving landholders from restoration or offsetting needs in 423 thousand hectares (kha) of NV. Scenario "1965/89" waved 507 kha of NV from restoration needs and represented a 59% reduction in LR deficit compared to the baseline scenario. The LR reduction by scenario "1965/89" assumed particular importance considering that the additional cutback was concentrated on Cerrado, an already very fragmented and impacted region. Together with reductions from other NVPL rules, the additional effects of Art. 68 unfolded great concerns about the role of LR as a tool for NV preservation on private land, threating governmental restoration commitments, and pointing that conservation command and control approaches should be complemented with incentive policies to achieve the desired and committed standards.

Resumo: A Lei de Proteção da Vegetação Nativa - 2012 - (LPVN) é a principal lei brasileira para proteção da vegetação nativa (VN) em terras privadas. A LPVN, atualmente em fase de implementação, reduziu os requerimentos de Reserva Legal (RL) presentes no Código Florestal (CF) de 1965 através de uma série de mecanismos legais. Entre eles, o Artigo 68 (Art.68) elimina a obrigação de recomposição ou restauração da VN convertida sem violação da lei vigente à época da conversão. O Art.68 é um dos mais controversos mecanismos da LPVN e cujos efeitos ainda não são conhecidos. Nós desenvolvemos um modelo para estimar os efeitos do Art.68 utilizando o estado de São Paulo, Brasil, como estudo de caso. Para isso, levantamos marcos legais nos quais os requerimentos mínimos de preservação da VN foram alterados. Em seguida, levantamos a existência de dados espaciais da cobertura de VN com a precisão necessária para cada marco legal. Combinando os marcos legais com os dados espaciais encontrados, criamos dois cenários incluindo os efeitos do Art.68 e um cenário linha de base para controlar tais efeitos. O primeiro cenário considerou apenas um marco legal, o CF de 1965 (cenário "1965"), enquanto o segundo incluiu a Lei Federal de proteção ao Cerrado de 1989 (cenário "1965/89"). O cenário "1965" reduz os déficits de RL em 49% quando comparado ao cenário de base, dispensando os proprietários de terra da obrigação de restaurar ou recompor 423 mil hectares (kha) de VN. O cenário "1989/65" dispensa da obrigação de restauração ou recomposição 507 kha de VN, representando uma redução de 59% do déficit de RL em comparação ao cenário base. A redução apresentada pelo cenário "1965/89" assume grande importância uma vez que se concentra em áreas de Cerrado, bioma já extremamente fragmentado e impactado. Em conjunto com as reduções promovidas por outros Artigos da LPVN, estes efeitos revelam grande preocupação sobre o papel das RL como uma ferramenta para a conservação de VN em terras privadas, ameaçando compromissos governamentais de restauração e indicando que estratégias de comando e controle deverão ser complementadas por políticas de incentivo para atingir os objetivos de conservação desejados.

Implicações do cumprimento do Código Florestal vigente na redução de áreas agrícolas: um estudo de caso da produção canavieira no Estado de São Paulo / Agricultural land reduction due to the compliance with the current Forest Code: a study case of sugarcane production in the State of São Paulo

Uma das principais justificativas da proposta de mudanças do Código Florestal brasileiro (CF) é a de que seu cumprimento supostamente inviabilizaria vários setores da agropecuária, apesar dessa justificativa ser fracamente sustentada em dados. O objetivo desse trabalho foi avaliar as implicações do cumprimento do CF para a redução de áreas de produção canavieira no Estado de São Paulo, visando estimar qual seria o limite superior de potenciais prejuízos que a aplicação do CF poderia trazer à viabilidade econômica de um dos mais importantes, e também impactantes ambientalmente, segmentos da produção agropecuária brasileira. Foram analisados 23 projetos de adequação ambiental conduzidos em 1.961 propriedades rurais de usinas sucroalcooleira do Estado de São Paulo, os quais totalizaram 533.097 ha (9,7 por cento da área cultivada com cana-de-açúcar em São Paulo). Nesses projetos, realizaram-se um diagnóstico ambiental de Áreas de Preservação Permanente (APP), áreas de produção agrícola e de áreas potenciais para constituir a Reserva Legal. Os resultados indicaram que 10,4 por cento da área total das propriedades rurais constituiriam APPs e que apenas 21,2 por cento da área de APP (2,2 por cento da área total) era utilizada por algum tipo de atividade agrícola, sendo que cana-de-açúcar ocupava apenas 12,1 por cento da área enquadrada como APP pelo atual Código (1,2 por cento da área total). Em média, 76,5 por cento da área total dos projetos estavam ocupadas por cana-de-açúcar e a soma das áreas potencias para a averbação da Reserva Legal, constituídas de remanescentes florestais (5,0 por cento da área total), áreas abandonadas (2,3 por cento da área total) e de áreas com outros usos (6,3 por cento da área total), resultaria em 13,6 por cento da área total, gerando um déficit médio de 6,4 por cento de áreas para o total cumprimento da Reserva Legal (20 por cento). Esse déficit poderia, por lei, inclusive ser compensado fora da matrícula, em paisagens de menor aptidão agrícola. Assim, o diagnóstico apresentado nesse trabalho para o setor canavieiro no Estado de São Paulo aponta que o CF vigente poderia ser cumprido sem inviabilizar a produção agrícola, ressaltando que parte dos argumentos favoráveis às alterações no CF precisa ser revista à luz de dados concretos e de forma menos especulativa.

One of the major reasons of the proposed changes of the Brazilian Forest Code is that its compliance would supposedly harm several agricultural sectors, although this reason has been weakly supported by data. The goal of this work was to evaluate the implication of the compliance with the Forest Code for reducing areas of sugarcane production in the State of São Paulo, aiming to estimate the upper limit of potential losses that the application of the Forest Code could bring to the economic viability of important sectors of Brazilian agricultural production. We analyzed 23 projects of environmental planning carried out in 1,961 landholdings of sugarcane mills from São Paulo State, which totalized 533,097 ha (9.7 percent of the cultivated area with sugarcane in the state). In these projects, we carried out an environmental zoning of Permanent Protected Areas (PPA), lands of agricultural production, and potential lands to constitute Legal Reserves. The results indicated that, on average, 10.4 percent of the total area of each farm was classified as PPA, and that only 21.2 percent of PPA area (2.2 percent of the total area) were occupied by some kind of agricultural production. Sugarcane occupied, in average, 12.1 percent of the areas classified as PPA (1.2 percent of the total area). Overall, 76.5 percent of the total area of projects was occupied by sugarcane fields and the sum of potential areas for compliance with the Legal Reserve, which were constituted by forest remnants (5.0 percent of total area), abandoned lands (2.3 percent of total area), and lands with other uses (6.3 percent of total area), would result in 13.6 percent of the total area and consequently generate a deficit of 6.4 percent of lands for the full compliance with the Legal Reserve (20 percent). This deficit could even be compensated, by law, outside the landholding register in landscapes with lower agriculture suitability. Therefore, the diagnostics presented in this work for the sugarcane sector in the State of São Paulo indicates that compliance with the current Forest Code would not reduce agricultural production, which highlight that part of the arguments that are favorable for changes in the Forest Code need to be revisited in the light of concrete data and in a less speculative way.

Ecologic salience and agreement on the identification of tree species from Brazilian Atlantic Forest / Saliência ecológica e concordância na identificação de espécies arbóreas de Mata Atlântica Brasileira

This study aims to investigate the consensus among informants in the naming of tree species from a high diversity environment, the Brazilian Atlantic Forest (Sete Barras, SP), through a methodological procedure based on standardized stimuli. Seven selected local experts on tree species used for timber and handicrafts were asked to walk individually across the same area of 1.72 ha and identify and name all the known trees of more than 4 cm DBH (diameter at breast height) using common names. All trees were botanically identified, and their DBH and height were measured. The ecologic salience of tree species, expressed in terms of abundance, average height and DBH, was tested in relation to the informants' knowledge and species naming. The guided walks resulted on 708 identification events, with common names corresponding to 122 botanical species, or 68 percent of all tree species present. Both the reduced abundance and ecological salience of rare species can explain their recognition. The highest concordances in naming a tree were related only to the species abundance and not to their size (given by diameter and height). In some cases, there is no single common name for a botanical species, reflecting the intrinsic variation in local knowledge, which must be considered in ethnobotanical studies, in ecological assessments based on local knowledge, as well as in community-based conservation and management programs.

Este estudo visa investigar o consenso entre informantes no reconhecimento e denominação de espécies arbóreas de um ambiente com alta diversidade, a floresta atlântica brasileira (Sete Barras, SP), através de um procedimento metodológico baseado em estímulos padronizados. Foram selecionados sete especialistas locais conhecedores de espécies arbóreas usadas para madeira e artesanatos, que percorreram individualmente uma mesma área de 1,72 ha para identificar e nomear todas as árvores conhecidas com mais de 4 cm de DAP (diâmetro na altura do peito) através de nomes populares. Todas as árvores foram identificadas botanicamente e tiveram seus DAP e altura determinados. A saliência ecológica das espécies arbóreas, expressa em termos da abundância, da altura média e do DAP, foi testada com relação ao conhecimento de cada informante em nomear as espécies. As caminhadas guiadas resultaram em 708 eventos de identificação, com nomes populares que correspondem a 122 espécies botânicas, ou a 68 por cento de todas as espécies arbóreas presentes. Tanto a reduzida abundância como a saliência ecológica de espécies raras podem explicar seu reconhecimento. As concordâncias mais elevadas em nomear uma árvore foram relacionadas somente à abundância da espécie e não ao seu tamanho (dado pelo diâmetro e pela altura). Em alguns casos, não há um único nome popular para uma espécie botânica, refletindo a variação intrínseca no conhecimento local, que deve ser considerada em estudos etnobotânicos, nas avaliações ecológicas baseadas no conhecimento local, assim como em programas de manejo e conservação participativos.

Classificação fitogeográfica das florestas do Alto Rio Xingu / Phytogeographical classification of the Upper Xingu River forest

Este trabalho propõe a inclusão da categoria Floresta Estacional Perenifólia no sistema oficial de classificação da vegetação brasileira, devido às particularidades florísticas e fisionômicas da floresta da borda sul-amazônica, que atinge maior amplitude geográfica na região do Alto Rio Xingu. Para justificar essa inclusão são apresentadas as características ambientais (clima, solo, hidrologia) e diferenças fisionômicas e florísticas entre as florestas do Alto Xingu e demais florestas ombrófilas da Bacia do Amazonas e estacionais do Planalto Central.

This paper proposes the inclusion of the "Evergreen Seasonal Forest" category in the official system used to classify Brazilian forests. This proposal is based upon the floristic and physiognomic particularities of the Southern Amazonian forest, which reach a greater magnitude around the Upper Xingu River. In order to justify the inclusion, the paper reports environmental characteristics (climate, soil and hydrology) as well as floristic and physiognomic differences between the Upper Xingu River forest and both the Ombrophilous Forest from the Amazon Basin and the Seasonal Forest of the Central Plateau.

Composição florística de trechos florestais na borda sul-amazônica / Floristic composition of forest patches in Southern Amazonia

Este estudo apresenta a composição florística de trechos de uma faixa de vegetação de transição existente na região centro-leste do Estado de Mato Grosso, mais precisamente no município de Gaúcha do Norte (13° 10'S e 53° 15' O), onde dá-se o contato entre a Floresta Ombrófila e a Floresta Estacional. O levantamento florístico foi realizado em março de 1999 e bimestralmente a partir de agosto de 1999 até março de 2001, em excursões com duração média de 5 dias, por meio de caminhadas na borda e no interior de florestas, sendo coletadas fanerógamas em fase reprodutiva. Também foram incluídas amostras vegetativas de espécies arbustivo-arbóreas, que não floresceram ou frutificaram durante o período de amostragem, amostradas em 3ha destinados ao levantamento fitossociológico. O levantamento florístico resultou em 72 famílias, 168 gêneros e 268 espécies. Do total de espécies, 66 por cento apresentaram hábito arbóreo e 18 por cento foram lianas. As ervas e arbustos praticamente restringiram-se às áreas de borda ou clareiras, somando 13 por cento. Já a flora epifítica mostrou-se pouco expressiva (1 por cento), quando comparada ao restante da Amazônia, em conseqüência do clima regional mais seco. Hemiepífitas, parasitas e palmeiras constituíram o percentual restante. Constatou-se que 39 espécies amostradas em Gaúcha do Norte ainda não haviam sido depositadas em herbários que mantém coleções representativas da flora matogrossense, enfatizando a carência de coletas nas áreas florestais do Estado.

Estrutura de um trecho de floresta Amazônica na bacia do alto rio Xingu / Structure of patch of Amazonian forest in the alto rio Xingu basin

Este estudo apresenta a estrutura de florestas em Gaúcha do Norte-MT (13° 10'S e 53° 15' O), na borda sul-amazônica. Para o levantamento fitossociológico, três áreas amostrais de 1ha foram subdivididas em 50 parcelas de 10x20m, nas quais foram amostrados todos os indivíduos com perímetro à altura do peito (PAP) >15 cm. Para verificar a similaridade estrutural entre as áreas utilizou-se a Análise de Correspondência. As espécies indicadoras dos ambientes de interflúvio e das áreas sujeitas à inundação foram obtidas através do TWINSPAN e de um sistema de pesos. Concluiu-se que as florestas presentes na bacia do rio Pacuneiro pertencem à mesma unidade fitogeográfica, mas com subtipos florísticos e estruturais de acordo com a posição no relevo, a proximidade dos cursos d'água e o estrato analisado, apresentando predominância de algumas espécies, ou até mesmo possíveis endemismos, em determinados trechos ou estratos. A formação apresentou baixa diversidade alfa (2,91 a 3,50) e beta (3,62 a 3,86), o que não é comum em florestas amazônicas. Várias hipóteses podem explicar essa baixa diversidade, entre elas a baixa precipitação e a alta sazonalidade, o ambiente físico regional aparentemente homogêneo e favorável às espécies competidoras, ou os eventos históricos, relacionados à possível exploração por tribos indígenas ou à recente expansão dessas florestas sobre as áreas savânicas.