ABSTRACT
ABSTRACT: The aim of this research was to characterize an environmental structure in the setting of tree natural water springs in a Lower Highland Seasonal Forest, and to verify the relationship between community demography and soil variables as subsidies for species identification in riparian forest recovery programs in similar environments. The research was carried out in the National Forest of Chapecó, located in the west of the state of Santa Catarina in the southern region of Brazil. For this, three water springs were demarcated, where 26 plots of 200m² in each were allocated. All individuals with diameter at 1.30m of soil height ≥5.0cm were measured. Soil samples (0 to 20cm depth) were collected in the plots for chemical and physical analysis. To relate the abundance of the species to the edaphic variables, the Canonical Correspondence Analysis (CCA) was used. A total of 76 species belonging to 64 genera of 36 botanical families were reported in the study area. The families Fabaceae and Myrtaceae presented greater floristic richness. The edaphic variables that most influenced the distribution of the species were aluminum saturation and calcium, magnesium and potassium contents. Specific groups of indicator species were formed for each water spring. The species designated as generalists are the most recommended for the initial filling and recovery of degraded springs. Further rare species and with low density must be included after the initial recovery to increase diversity.
RESUMO: O presente trabalho teve como objetivo caracterizar a vegetação arbórea em nascentes de Floresta Latifoliada Subtropical e verificar a relação entre a demografia da comunidade e variáveis edáficas, como subsídios para indicação de espécies em programas de recuperação de florestas ciliares de ambientes similares. O trabalho foi realizado na Floresta Nacional de Chapecó, localizada no oeste do estado de Santa Catarina no sul do Brasil. Para isso, foram demarcadas três nascentes, onde foram alocadas 26 parcelas de 200m2 em cada uma. Todas as árvores com Diâmetro a Altura do Peito (DAP) ≥5,0cm a 1,30m de altura do solo foram mensurados. Coletaram-se amostras de solo (0 a 20cm de profundidade) nas parcelas para análise das propriedades químicas e físicas. Para relacionar a abundância das espécies com as variáveis edáficas utilizou-se a Análise de Correspondência Canônica (CCA). Foram encontradas na área de estudo, 76 espécies pertencentes a 64 gêneros de 36 famílias botânicas. As famílias Fabaceae e Myrtaceae apresentaram maior riqueza florística. As variáveis edáficas que mais influenciaram na distribuição das espécies foram a saturação por alumínio e os teores de cálcio, magnésio e potássio. Ocorreu a formação de grupos específicos de espécies indicadoras para cada nascente. As espécies designadas como generalistas são as mais recomendadas para a recomposição de nascentes com a função de preenchimento inicial da área. Enquanto as espécies raras e de baixa densidade devem ser incluídas após a recuperação inicial com a função de aumentar a diversidade.
ABSTRACT
Soil and forest structure in the Colombian Amazon. Forests structural differences could result of environmental variations at different scales. Because soils are an important component of plant’s environment, it is possible that edaphic and structural variables are associated and that, in consequence, spatial autocorrelation occurs. This paper aims to answer two questions: (1) are structural and edaphic variables associated at local scale in a terra firme forest of Colombian Amazonia? and (2) are these variables regionalized at the scale of work? To answer these questions we analyzed the data of a 6ha plot established in a terra firme forest of the Amacayacu National Park. Structural variables included basal area and density of large trees (diameter≥10cm) (Gdos and Ndos), basal area and density of understory individuals (diameter<10cm) (Gsot and Nsot) and number of species of large trees (sp). Edaphic variables included were pH, organic matter, P, Mg, Ca, K, Al, sand, silt and clay. Structural and edaphic variables were reduced through a principal component analysis (PCA); then, the association between edaphic and structural components from PCA was evaluated by multiple regressions. The existence of regionalization of these variables was studied through isotropic variograms, and autocorrelated variables were spatially mapped. PCA found two significant components for structure, corresponding to the structure of large trees (G, Gdos, Ndos and sp) and of small trees (N, Nsot and Gsot), which explained 43.9% and 36.2% of total variance, respectively. Four components were identified for edaphic variables, which globally explained 81.9% of total variance and basically represent drainage and soil fertility. Regression analyses were significant (p<0.05) and showed that the structure of both large and small trees is associated with greater sand contents and low soil fertility, though they explained a low proportion of total variability (R² was 4.9% and 16.5% for the structure of large trees and small tress, respectively). variables with spatial autocorrelation were the structure of small trees, Al, silt, and sand. Among them, Nsot and sand content showed similar patterns of spatial distribution inside the plot. Rev. Biol. Trop. 59 (3): 1307-1322. Epub 2011 September 01.
Las diferencias estructurales del bosque pueden ser el producto de variaciones ambientales a diferentes escalas, entre ellas los suelos. Para evaluar tal asociación, se usaron los datos de estructura del bosque y de suelos de una parcela de 6ha establecida en un bosque de tierra firme de la Amazonía colombiana. Las variables edáficas y estructurales se redujeron con un análisis de componentes principales (ACP) y un análisis de regresión múltiple verificó si existía asociación entre los componentes edáficos y estructurales del ACP. La regionalización de las variables de estudio se verificó con variogramas isotrópicos; además, se construyeron mapas de distribución espacial. El ACP de las variables estructurales identificó dos componentes: dosel y sotobosque, los cuales explicaron el 43.9 y 36.2% de la varianza total, respectivamente; para las variables edáficas los cuatro primeros componentes explicaron globalmente el 81.9% de la varianza total. Los análisis de regresión mostraron que tanto el dosel como el sotobosque se asocian con mayores contenidos de arena y baja fertilidad del suelo (p<0.05), pero explicaron una proporción baja de la variabilidad total (R²=4.9% para dosel y 16.5% para sotobosque). Las tres variables de la estructura del sotobosque, Al, limo y arena presentaron autocorrelación espacial.