RESUMO Estudos de dinâmica de florestas manejadas são fundamentais para planejamento e execução de estratégias de condução das florestas. As intervenções de colheita madeireira podem modificar taxas de recrutamento, mortalidade, ganho e perda de área basal da floresta remanescente. Em florestas secundárias, especialmente na Mata Atlântica, estes estudos ainda são escassos. Nossa hipótese de pesquisa é que a intervenção de manejo estimule o crescimento das árvores remanescentes, superando a redução do crescimento das árvores danificadas e mortalidade da colheita. Foi investigado a dinâmica das árvores remanescentes e dos recrutas (em número de indivíduos e área basal), com DAP ≥ 5 cm, por grupo ecológico da espécie, e os danos nos indivíduos adultos remanescentes. Medimos onze parcelas permanentes, com área de 1600 m², antes e quatro anos após a colheita de madeira em uma floresta secundária no sul do Brasil. Verificamos que as diferentes intensidades de colheita influenciam significativamente a dinâmica da floresta, especialmente as taxas de recrutamento anual, enquanto perda e ganho de área basal apresentaram uma relação mais fraca com a intensidade de corte; as taxas de mortalidade, no entanto, são semelhantes em parcelas de controle e parcelas manejadas. Também observamos que nas parcelas manejadas a taxa de recrutamento (5.3 ± 1.9 % /ano) superou a mortalidade (2.3 ± 1.2 % / ano). Entre os grupos ecológicos, encontramos menos recrutamento de espécies clímax do que de espécies secundárias. Em geral, a proporção de danos às árvores remanescentes diminuiu com o tempo. Concluímos que o manejo modificou a dinâmica florestal, indicando que o planejamento, incluindo limites de corte adequados e métodos de colheita de baixo impacto são essenciais para o alcance de um manejo florestal sustentável.

ABSTRACT Studies on the dynamics of managed forests are essential for planning and executing management strategies. Timber harvesting can modify recruitment rates, mortality, gain and loss of basal area of the remaining stand. In secondary forests, especially in the Atlantic Forest, these studies are still scarce. Our study hypothesis is that the management intervention stimulates the growth of the remaining trees, overcoming the reduction of the growth of the damaged trees and the harvest mortality. We investigated the dynamics of the remaining trees and recruits (in number of individuals and basal area), with DBH ≥ 5 cm, by ecological group of the species, and the damage to the remaining adult individuals. We measured eleven permanent plots with 1.600m² each, before and four years after being harvested in a secondary forest in southern Brazil. We found that the different harvesting intensities significantly influence the forest dynamics, special the annual recruitment rates, while basal area gain/loss showed a weaker relationship to logging intensity. However, the mortality rates are similar in control plots and managed plots. We also observed that in the managed plots, the recruitment rate (5.3 ± 1.9% year-¹) exceeded mortality (2.3 ± 1.2% year-¹). Among ecological groups, we found less recruitment of climax species than of secondary species. In general, the proportion of damage of remaining trees decreased over time. We conclude that the management has modified the forest dynamics, indicating that planning, including adequate cutting limits and low impact harvesting methods are essential for achieving the sustainability of forest management.

Abstract The highly biodiverse Atlantic Forest has been heavily exploited and its remnant areas, which are mostly composed of secondary forests, cover less than 20% of its original extension. This study analyzed the structure, aboveground biomass (AGB) and species diversity of a secondary evergreen rainforest in the state of Santa Catarina, southern Brazil. Individuals with diameter at breast height ≥ 5 cm on 22 sample plots were measured, totalizing 3.49 hectares of sampled area. A mean AGB of 201.6 Mg ha-1 (standard deviation = 35.5) was found; Hyeronima alchorneoides and Miconia cinnamomifolia represented 29.1% and 7.6% of the community AGB ha-1, respectively. A total of 153 species distributed in 107 genera and 55 families was observed; it was estimated that 121 species (95% confidence interval: [117, 125]) occurred in one hectare. These results highlight the importance of secondary forests for biodiversity restoration/conservation and carbon sequestration.

ABSTRACT Background: Understanding forest dynamics after logging is essential to define forest management cycles and intensities. In secondary forest, especially in the Atlantic Forest Domain, these studies are still scarce. Monitoring of the canopy structure after tree harvesting can be performed by hemispherical photographs, where canopy opening is commonly analyzed. This study evaluated changes in canopy opening four years after tree harvesting in a secondary Atlantic Rainforest in southern Brazil. We used hemispherical photographs to determine the Canopy Openness (CO), Leaf Area Index (LAI), and Diffuse Fraction of Photosynthetically Active Absorbed Radiation (FAPARdif) in eleven permanent plots. Results: We found that harvesting resulted in a momentary increase in canopy opening and light availability in the understory. Four years after harvesting, CO, LAI and FAPARdif recovered or even exceeded the original values of the forest. We observed a significant correlation between CO and number of trees harvested with DBH > 30 cm. Weak correlations were found between these canopy related variables and the logging intensity. Conclusion: In conclusion, we recognized that changes of CO, LAI and FAPARdif after timber harvesting presented short duration. This indicates that the applied logging intensities, 21.8 to 51.1% of the total basal area, did not exceed the resilience of the forest canopy and it’s recovering four years later. However, additional studies should be carried out to observe vegetation dynamics, such as species composition, vertical structure, productivity and community stability, in order to improve management schemes of secondary stands in the Atlantic Forest.

Abstract: A challenge for the use of medium spatial resolution imagery for land use change detection consists of the reduced availability of ground reference data for previous dates. This study aims to obtain invariant training points using the backdating process for supervised classification of images that have no field data available. The study area comprises 1,353 km² in Santa Catarina, southern Brazil. We compared the accuracy performance of invariant area sets (binary change maps) generated by using three methods (IR-MAD - Iteratively Reweighted Multivariate Alteration Detection, CVA - Change Vector Analysis and SGD - Spectral Gradient Difference) for two periods (2017-2011 and 2011-2006). The classification of the Landsat-5 TM image of 2006 was performed using as training data the sets of points indicated as invariant in the binary maps resulted from the three abovementioned methods. The accuracies for seven land-use classes were computed. The overall accuracy was greater (80,5% and 80,2%) when using training areas achieved by CVA and SGD, respectively than IR-MAD (76%). Were obtained accuracies greater than 80% for the forest class. The results stress that the combination of the IR-MAD and SGD is preferable since the CVA is more time consuming due to the subjective application of thresholds.

ABSTRACT In Santa Catarina State, forest classification in successional stages is supported by the National Council of the Environment (CONAMA) Resolution. However, this classification presents several inconsistencies. This study aimed to evaluate the classification accuracy of three classifications schemes of successional stages proposed for the Subtropical Atlantic Evergreen Rainforest of the Santa Catarina State. All schemes are based on threshold values of mean height, mean diameter at breast height, and basal area to distinguish between stages. We used structural and diversity data from 207 sample plots within the Santa Catarina’s State Subtropical Rainforest region to classify the respective stands according to the schemes. The classification accuracy of each scheme was evaluated through the application of linear discriminant analysis (LDA). We constructed a predictive equation using the results of the LDA, from the scheme that presented highest classification accuracy. The current classification (CONAMA Resolution) showed an average of 81.87% of classification accuracy, while Scenario A presented 83.73% and Scenario B 78.67%. From Scenario A, we created a predictive equation based on structural and diversity variables. This equation may be used to classify other forest sites, constituting a new proposal for the secondary vegetation classification in Santa Catarina’s State Subtropical Rainforest.

ABSTRACT: A key issue in large-area inventories is defining a suitable sampling design and the effort required to obtain reliable estimates of species richness and forest attributes, especially in species-diverse forests. To address this issue, data from 418 systematically distributed 0.4 ha plots were collected. Estimators of nonparametric species richness were employed to assess the floristic representativeness of data collected in three forest types in the Brazilian Atlantic Forest. The sampling sufficiency of forest attributes was evaluated as a function of sample size. Altogether, 831 tree/shrub species were recorded. The data acquired through the systematic sampling design were representative of both species richness and basal area. The confidence intervals’ length would not substantially decrease by using more than 70 % of the reference sample (n = 364), thereby reaching a length of ∼5 % of the sample mean. Nevertheless, reliable estimates of species richness for diverse forests demand a thorough sampling approach far more exacting so as to achieve acceptable population estimates of forest attributes. Though the study area is regarded as a biodiversity hotspot, the forest stands showed diminished species richness, basal area, stem volume and biomass when compared to old-growth stands. As regards species richness, the data provided evidence of contrasting great γ-diversity (at the forest type level) and small α-diversity (at the forest stand level). Amongst anthropic impacts, illegal logging and extensive cattle grazing within stands are undoubtedly key factors that threaten forest conservation in the study area.

ABSTRACT: Araucaria angustifolia (Bertol.) Kuntze is a native tree species of major importance in southern Brazil. It is a regional symbol due to its iconic shape and stature in the landscape; its wood was once economically important and its seeds are an important source of food for the fauna and are presently used in regional cuisine. Despite its importance and apparent abundance, the species is facing extinction mainly as a result of unregulated exploitation and deforestation. This study catalogued the remaining individuals in order to add to the body of knowledge available on A. angustifolia, a species that has become rare across its historic range. The circumference at breast height (1.30 m), the total height, and the tree volume were measured (3,529 araucarias). We catalogued trees with a large diameter measuring them in loco over three years involving a journey of more than 6,800 km. The volumes of these old trees are very large, ranging from 38.2 m3 to 106.6 m3. The largest A. angustifolia individual is located in the state of Santa Catarina and measures 3.25 m in diameter. The giant araucarias with > 2.00 m in diameter are rare and only 13 individuals could be found in southern Brazil; a priority action at the governmental level is to recognize and preserve these monumental trees and together with a need for a public policy of drawing up specific inventories of large trees.

ABSTRACT Loss of large trees due to indiscriminate timber cutting and opening of new areas for human use is a global problem. Brazil is well known for tree species richness within its extensive forested areas composed of various biomes. Giant trees are “key” to recognize the original forest structure. Decline of their populations in Brazil may be estimated by comparing data of the National Forest Inventory (NFI) with those of regional data and other surveys. In fact, Santa Catarina is the first state in Brazil to have currently completed its forest inventory. However, only few large trees were sampled systematically. Recognition of the maximum tree growth is important for their ecological management and tourism potential. Public policies for cataloging and management of these resources must be developed before it is too late.

ABSTRACT Sustainable forest management promotes financial revenues while keeping the forest cover and environmental services. Nevertheless, the logging operation causes changes in the forest and canopy horizontal and vertical structure. Our objective is to evaluate the changes in the forest canopy and its consequences to the forest management, following logging in a secondary Atlantic Rainforest. We used hemispherical photography to determine the Canopy Openness (CO), Leaf Area Index (LAI) and the radiation absorption (fAPAR) in nine experimental plots before and after logging. We did not find a clear correlation between the forest horizontal structure and the canopy architecture. Despite this, there was an increase in CO and decrease in LAI and fAPAR after logging. The variation in CO and fAPAR were affected by logging intensity, but LAI did not show the same pattern. We suggest a conservative maximum logging intensity of 30% of the basal area and tree density.

Neste estudo foi abordada a segmentação de imagens de alta resolução e a utilização da técnica da mineração de dados. O objetivo foi encontrar correlação entre resposta espectral, espacial, de contexto e de textura, e variáveis dendrométricas obtidas de inventários florestais em áreas de estágio inicial de sucessão da Floresta Ombrófila Densa em três locais do Estado de Santa Catarina. Os dados de campo foram levantados em seis Unidades Amostrais (UA) com 1.600 m² cada. No processamento digital utilizaram-se três imagens de alta resolução espacial (0,39 m) obtidas pelo sensor SAAPI, com três bandas no visível, três no infravermelho próximo, modelo numérico de terreno e de superfície. Dados extraídos do produto digital (atributos) foram utilizados na etapa da mineração dos dados, que selecionou atributos relevantes e descartou aqueles de menor peso. Verificou-se que tanto no estrato arbóreo quanto na regeneração existe heterogeneidade de variáveis, como número de indivíduos (N), diâmetro a altura do peito (DAP) e área basal (AB). Mesmo assim, foram encontradas correlações significativas entre atributos das imagens e os dados de campo. A correlação de maior magnitude absoluta de N foi com as médias da banda 1 (-0,64), 3 (-0,62) e IR1 (0,63), para DAP foi a razão das bandas IR3 (0,56) e 2 (0,55) e para AB foi o menor valor de pixel das bandas 1 (-0,64) e IR3 (-0,60), todas altamente significativas (p<0,01). Esses resultados configuram pontos de partida para futuras investigações a respeito da construção de um estimador de parâmetros biofísicos da vegetação.

High-resolution image segmentation and data mining techniques were used in order to find statistical correlation between spatial, spectral, context and texture attributes, considering field data from early stages of secondary forests in the three study sites of Rain Forest in Santa Catarina State, Brazil. Field data were collected in six sampling plots with 1,600 m² each. Digital processing utilized three high resolution images (0.39 m) obtained by SAAPI sensor with three visible bands, three near infrared bands, one terrain and one surface model. Extracted data from the digital product (attributes) were used for data mining purposes, selecting the ones with relevance and dismissing those of lesser weight. It was found that both tree and regeneration layers are heterogeneous considering number of individuals (N), diameter at breast height (DBH) and basal area (AB). However, significant correlations between forest attributes and field data were found. The higher correlation of N is with the average of the band 1 (-0.64), 3 (-0.62) and IR1 (0.63) for DBH was the ratio of bands IR3 (0.56) and 2 (0.55) and the variable AB was the smallest pixel value of band 1 (-0.64) and IR3 (-0.60). All correlation coefficients were highly significant (p <0.01). These results constitute the starting point for future research on the relationship between groups of variables in order to estimate biophysical parameters

O presente trabalho teve por objetivo caracterizar os remanescentes da Floresta Ombrófila Densa, no estado de Santa Catarina. O conjunto de dados utilizado neste estudo foi disponibilizado pelo projeto Inventário Florístico Florestal de Santa Catarina, sendo oriundo de 197 unidades amostrais do tipo conglomerado. Os conglomerados foram constituídos por quatro subunidades de 20 x 50 m, nas quais foram mensurados todos os indivíduos arbóreo-arbustivos com DAP ≥ 10 cm. A estrutura da floresta foi caracterizada com o emprego de parâmetros e índices fitossociológicos. Com base na densidade das espécies, foram realizadas análises de agrupamento e ordenação na tentativa de identificar grupos de bacias hidrográficas e faixas de altitude. Foram encontradas 577 espécies, pertencentes a 226 gêneros e 83 famílias. As famílias mais representativas em número de espécies e indivíduos foram Myrtaceae, Lauraceae e Fabaceae. Espécies de áreas perturbadas como Alchornea triplinervia, Caseria sylvestris e Miconia cinnamomifolia estão dentre as que dominam a floresta. Por meio da análise de agrupamento, foi possível identificar três formações ao longo do gradiente altitudinal, aqui denominadas: Floresta Ombrófila Densa de Terras Baixas (< 30 m), Submontana (30 - 500 m) e Montana (> 500 m). Variações florísticas e estruturais puderam ser detectadas entre as três formações. Em comunidades das terras baixas, a presença das famílias Anacardiaceae e Clusiaceae foi mais expressiva e a altura média das árvores foi superior. Nos ambientes montanos, observou-se um aumento no número de indivíduos, área basal e diversidade, além da maior representatividade das famílias Cyatheaceae, Lauraceae e Rubiaceae. A ocorrência de Arecaceae foi marcante nos patamares submontanos. Grupos espaciais não puderam ser seguramente definidos a partir de dados estruturais de bacias hidrográficas.

This study aimed to characterize the remnants of Ombrophilous Dense Forest in Santa Catarina state. The dataset used in this study was provided by Project of Floristic and Forest Inventory of Santa Catarina, coming from 197 sample units that consist of basic clusters. The basic cluster was composed of four subunits of 20 x 50 m, in which all individuals with DBH ≥ 10 cm were measured. The forest structure was characterized through phytosociological parameters and indices. Based on structural data of the species, cluster analysis and ordination were performed in an attempt to identify groups of watersheds and altitude ranges. It was identified 577 species belonging to 226 genera and 83 families. The most representative families in number of species and individuals were Myrtaceae, Lauraceae and Fabaceae. Species of disturbed areas as Alchornea triplinervia, Caseria sylvestris and Miconia cinnamomifolia were dominant in the forest. Cluster analysis resulted in the identification of three vegetation types along the altitudinal gradient: Lowland Ombrophilous Dense Forest (< 30 m a.s.l.), Submontane (30 - 500 m) and Montane (> 500 m). Floristic and structural variations could be detected between the three vegetation types. In lowland communities, the presence of Anacardiaceae and Clusiaceae was more expressive and the average height of trees was higher. In montane environments, there was an increase in the number of individuals, basal area and diversity, as well as a greater representation of Cyatheaceae, Lauraceae and Rubiaceae. The occurrence of Arecaceae was remarkable in submontane forest. Spatial groups could not be defined based on structural data of watersheds.

Este trabalho teve por objetivo analisar o uso da terra no entorno de 143 unidades amostrais (UA) na floresta ombrófila mista em Santa Catarina e verificar a possível relação do uso da terra com o estado da vegetação. Foram utilizados um mapeamento do uso da terra de 2005 e dados da vegetação coletados em 143 UA do Inventário Florístico Florestal de Santa Catarina (IFFSC) entre 2007 e 2009. O entorno foi delimitado por buffers de distâncias distintas a partir do centro da UA. A cobertura florestal dos entornos e a distância entre a UA e a borda do fragmento apresentaram correlação significativa com riqueza e abundância de espécies climácicas, além de correlação negativa com riqueza e abundância de espécies pioneiras (α = 0,05) no fragmento. As paisagens com maior cobertura florestal e com maiores fragmentos permitem a manutenção de florestas mais bem conservadas e com menor influência da matriz no entorno.

This study aimed to analyze the use of surrounding land of 143 sample plots in the mixed ombrophilous forest in Santa Catarina and investigate a possible relationship of land use with the vegetation status. We used a land use map in 2005 and vegetation data from 143 sample plots (SP) from the Floristic Forest Inventory of Santa Catarina (IFFSC) collected between 2007 and 2009. The surroundings were delimited by buffers of different distances from the SP center. Forest coverage and distance between SP and fragment edge showed significant correlations with richness and abundance of climax species and a negative correlation with richness and abundance of pioneer species (α=0.05) in the fragment. The landscapes with greater forest coverage and larger patches allow the best preserved forest maintenance and show less influence of the surrounding matrix.

<p>Em florestas naturais, a altura total das árvores (h) é, muitas vezes, difícil de medir. Nesses casos, modelos de regressão baseados em variáveis de fácil medição, como o DAP (d), são uma alternativa, desde que seus pressupostos sejam atendidos. Neste estudo, objetivou-se i) o ajuste de modelos hipsométricos para três tipologias florestais de Santa Catarina (Floresta Estacional Decidual, Floresta Ombrófila Mista, Floresta Ombrófila Densa), testando os pressupostos e avaliando a qualidade dos ajustes; ii) verificação de diferenças das relações hipsométricas entre as tipologias florestais e entre os modelos ajustados baseados em alturas medidas e estimadas. Os dados de 1.766 alturas medidas e 3.150 alturas estimadas em campo foram coletados pelo Inventário Florístico Florestal de Santa Catarina (IFFSC), em 418 unidades amostrais. Os modelos foram ajustados para ambos os conjuntos de dados. Modelos específicos foram ajustados para espécies com ≥ 30 árvores medidas; normalidade, aleatoriedade e homoscedasticidade dos resíduos foram avaliadas analiticamente. Bandas com intervalos de confiança foram construídas pelo método Working-Hotelling; teste z para médias foi aplicado para comparar os modelos baseados nos dois conjuntos de dados. Parâmetros estatísticos como o AIC evidenciaram melhor ajuste dos modelos logarítmicos. Foram encontradas diferenças nas relações h/d entre as tipologias florestais (DEN e MIX) e entre os conjuntos de dados. O uso de modelos hipsométricos é uma alternativa para estudar a relação h/d e para determinar padrões da estrutura vertical em comunidades florestais, quando a medição de h não é viável, embora em casos da necessidade de maior acurácia das alturas estimadas, os modelos nem sempre possam fornecê-las.</p>

<p>Total tree height (h) is often difficult to measure in natural forests. Regression models based on easily accessed variables like DBH (d) can be an alternative, since their assumptions are validated. The aims of this study are to: (i) calibrate specific and generic h-d models for three forest types (Seasonal Deciduous Forest, DEC; Mixed Ombrophilous Forest, MIX; and Dense Rainforest, DEN) in Santa Catarina state testing the regression assumptions and evaluating model quality; (ii) verify different h-d relationship between forest types. The dataset (1,766 measured tree h and 3,150 estimated h) was collected by Santa Catarina Forest and Floristic Inventory (IFFSC) in 418 systematically located sample plots. Models were calibrated for two datasets, one containing hypsometer measurements, the other h estimations made by field crews. Specific models were calibrated for species with at least 30 sampled trees. Residual normality, randomness and heteroskedasticity were evaluated by analytical methods. Confidence bands were generated by the Working-Hotelling method; z test for means was applied to compare models based on the two databases. The statistical parameters such as corrected Akaike Information Criterion provided evidences that logarithmic models were better adjusted to the data. Both datasets were statistically different for DEN and MIX. Differences in h-d relationships were found between forest types. The use of calibrated h-d models is an alternative for studying the relationships between these variables and to assess vertical structure patterns of forest communities, when h measurements are not feasible, although, for situations that more accurate h values are needed, they will not always provide reliable predictions.</p>

O objetivo deste trabalho foi identificar as possíveis similaridades estruturais entre remanescentes da Floresta Estacional Decidual (FED) em Santa Catarina e associar os grupos à influência de condicionantes ambientais. Associado a este objetivo primário, também se buscou a identificação das zonas de contato entre esta tipologia florestal e a Floresta Ombrófila Mista (FOM). Foram analisados os dados de 78 unidades amostrais (UA) instaladas em remanescentes da FED entre 2008 e 2009 pelo Inventário Florístico Florestal de Santa Catarina (IFFSC). Os dados foram tratados através da Análise de Correspondência Corrigida (DCA) e da Análise de Correspondência Canônica (ACC), valendo-se de uma matriz de densidade de espécies e uma matriz de variáveis ambientais, esta constituída por altitude e parâmetros climáticos. A proporção da variância explicada pelos três primeiros eixos da DCA foi baixa, somando aproximadamente 21% do total de informação contida no conjunto original de dados. Este resultado ofereceu baixo poder de interpretação para os resultados. No entanto, quando a DCA foi aplicada sobre os dados de densidade média das espécies em cada bacia hidrográfica, os resultados apontaram para autovetores muito explicativos do conjunto (58,1% da variação). Observada somente a ordenação provocada pelo primeiro eixo da DCA, vê-se a disposição das bacias de leste, em um extremo, e das bacias de oeste, no outro extremo deste eixo. Na extremidade direita do primeiro eixo estão dispostas as bacias do rio Canoas, Pelotas e do Peixe, as quais são caracterizadas pela presença de espécies como Ocotea pulchella, Zanthoxylum fagara, Lithrea brasiliensis, Matayba elaeagnoides, Cinnamodendron dinisii, comumente associadas com a Floresta Ombrófila Mista. Na extremidade esquerda estão distribuídas as bacias de oeste, grupo que inclui as bacias dos rios Jacutinga, Irani, Chapecó, Antas e Peperi-Guaçu. Dentre as espécies que mais fortemente influenciaram os resultados na análise, cabe destacar Apuleia leiocarpa, Rauvolfia sellowii, Bastardiopsis densiflora, Chrysophyllum gonocarpum, Cordia trichotoma, Holocalyx balansae, Myrocarpus frondosus e Pisonia zapallo, as quais são frequentes em florestas estacionais do interior meridional do Brasil. A análise através da ACC apontou para resultados similares e a interpretação conjunta dos dados ambientais indicou que as UA situadas nas bacias de leste estão associadas a climas mais frios, em que as geadas são mais frequentes, como consequência de altitudes mais elevadas. Considerando que as altitudes tendem a declinar das porções lestes para oeste e, diante do resultados apresentados, os autores propõem a existência de uma zona de transição entre as duas regiões fitoecológicas (FOM e FED) na faixa dos 600 m s.n.m., onde ocorre a interdigitação de elementos da flora estacional e aqueles da Floresta Ombrófila Mista, resultando na delimitação de uma área core da FED abaixo deste patamar altimétrico.

This study aims to identify structural similarities between the remnants of seasonal deciduous forest (SDF) in Santa Catarina state and check the influence of environmental factors that leads the formation of these groups. Associated with this primary objective, it was also sought to identify the areas of contact between this forest type and Araucaria forest (mixed ombrophilous forest - MOF). We analyzed data from 78 sample units (AU) installed in the remnants of SDF between 2008 and 2009 by professional team of Floristic and Forest Inventory of Santa Catarina project (IFFSC). The data were processed through the Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA), using a matrix of species density associated with a environmental variables matrix, that consisted of altitude and climate parameters. The proportion of variance explained by the first three axes of DCA was low, accounting for approximately 21% of the information contained in the original data set. This result provides low power of interpretation of the results. However, when DCA was applied to the data of mean density of species in each river basin, the results pointed to better explanatory eigenvectors (three first eigenvectors explain 58.1% of total variance). The first ordination axis of DCA grouped the eastern watersheds SUs at one end, and the western watersheds SUs at the other end of this axis. At the right end of the first axis are arranged the watersheds of the river Canoas, Pelotas and Peixe, which are characterized by the presence of species such as Ocotea pulchella, Zanthoxylum fagara, Lithrea brasiliensis, Matayba elaeagnoides, Cinnamodendron dinisii commonly associated with Mixed Ombrophilous Forest (Araucaria forest). At the left end, the grouped SUs are mainly those of western watersheds, a group that includes the basins of the Jacutinga, Irani, Chapecó, Antas and Peperi-guaçu rivers. Among the species that most strongly influence the results in the analysis, we highlight Apuleia leiocarpa, Rauvolfia sellowii, Bastardiopsis densiflora, Chrysophyllum gonocarpum, Cordia trichotoma, Holocalyx balansae, Myrocarpus frondosus and Pisonia zapallo, which are common in seasonal forests of the hinterlands of southern Brazil. The analysis through the ACC pointed to similar results and joint interpretation of environmental data indicated that the basins located in the east are associated with colder climates where frosts are more frequent as a result of higher altitudes. As the altitudes tend to decline from east to west and portions, the authors propose the existence of a transition zone between the two phytoecological regions (MOF and SDF) in the range of 600 m asl, where occurs the interdigitation of elements from seasonal flora and those of Araucaria forest, resulting in the delineation of a core area of the SDF below this altitudinal level.

O estudo objetivou avaliar a fitossociologia da Floresta Estacional Decidual no Estado de Santa Catarina, em seus componentes arbóreo/arbustivo e regeneração natural, bem como comparar estes quanto à composição florística e inferir sobre o estádio de conservação dos remanescentes. Foram usados dados de 78 unidades amostrais levantadas no Inventário Florístico Florestal do Estado de Santa Catarina. Em cada unidade amostral foram amostrados os componentes arbóreo/arbustivo (DAP ≥ 10 cm) em 4000 m2 e a regeneração natural (altura ≥ 1,50 m; DAP < 10 cm) em 100 m2. Foi efetuado o cálculo dos parâmetros fitossociológicos e índices de diversidade de Shannon e equabilidade, bem como, classificaram-se as espécies quanto ao grupo ecológico. Para verificar a associação entre os dois componentes executou-se uma análise de ordenação NMSD (Non-metric Multidimensional Scaling) seguida do Teste de Mantel. Foram amostradas 245 espécies, sendo 215 no componente arbóreo/arbustivo e 79 exclusivas deste, 165 na regeneração natural e 30 exclusivas deste e, 136 comuns aos dois componentes. A NMDS apresentou uma tendência de associação entre as matrizes dos dois componentes, o que foi confirmado pelo Teste de Mantel (r = 0,34; p = 0,001). A composição florística, bem como as espécies com maiores valores de importância se constituíram predominantemente de espécies secundárias, fato que evidencia o histórico de exploração e degradação da Floresta Estacional Decidual no Estado.

This study aimed to evaluate the species composition and structure of Seasonal Deciduous Forest in the southern Brazilian state of Santa Catarina, including the tree/shrub component and the natural regeneration. We also compared the floristic composition between the components and discussed about the conservation condition of forests. The study was based on sample plots established by the Floristic and Forest Inventory of Santa Catarina state. Tree/shrub component was sampled by 78 plots placed systematically with 4,000 m2 of sample area each, were individuals with DBH (diameter at breast height) ≥ 10 cm was measured. Regeneration (DBH <10 cm and height >1.50 m) was sampled in subplots of 100 m2 each. Structure and diversity of sample plots were analyzed in both components; species were classified by their ecologic group. To test the association between components was made a Non-metric Multidimensional Scaling (NMSD) and Mantel test. We sampled 245 species, among them 215 in the tree/shrub component (79 of them exclusive), 165 species in the natural regeneration (30 exclusive ones) and 136 species common to the two components. The association between components was confirmed with NMSD and Mantel test (r = 0.34; p = 0.001). Species with major importance value were mostly early secondary species that emphasizes the consequences of long term exploitation and degradation of Seasonal Deciduous Forest in Santa Catarina.