Abstract Plant community succession is generally approached with phytosociological methods, but field surveys are time-consuming, expensive, and limited to several of sites. Remote sensing offers an efficient and economical way to analyze vegetation on large extensions and in inaccessible areas. Most studies addressing remote sensing and tree community succession refer to forest physiognomies. We investigated whether structural changes that occur in non-forest physiognomies are identified by multispectral sensor images (OLI-Landsat). Thirteen 0.1-ha plots were set up in Caatinga fragments aging 10-15, 20-25, 30-35, 40-45 and >50 years to calculate the total density of individuals (TD), mean canopy height (H), total basal area (G) and total aboveground biomass (AGB). We performed correlation analyses between these structural descriptors and eight remote sensing variables (reflectance data and spectral indices) obtained from Landsat images at the end of the rainy season and during the dry season. Blue and short-wave infrared reflectances were negatively correlated with mean height, basal area and biomass, regardless of the analyzed scene (coefficients between -0.58 and -0.79). The litter layer (a non-photosynthetic vegetation component) and the soil exposure are important factors influencing the spectral data.

Este trabalho apresenta a parametrização do submodelo espectral do modelo JONG, um modelo agrometeorológico-espectral para a previsão da disponibilidade de forragem das pastagens naturais do bioma Campos Sulinos. A parametrização foi feita testando-se a capacidade de diferentes variáveis espectrais obtidas a partir de imagens do sensor ETM+/Landsat 7 representando a disponibilidade de forragem em diferentes fases do ciclo fenológico da vegetação campestre natural do bioma Campos Sulinos. Verificou-se que as variáveis Wetness e reflectância da banda ETM+7/Landsat 7 representam o status inicial da vegetação de forma eficiente, mas não tiveram sensibilidade suficiente para eliminar os efeitos do tipo de solo na resposta espectral da vegetação.

This research presents the parameterization for the spectral submodel of JONG model, an agrometeorologic-spectral model to forecast the available forage of natural pastures of Campos Sulinos biome. Tthe capacity of different spectral variables, gotten from images of the sensor ETM+/Landsat 7, to represent the forage availability in different phases of its fenologic cycle was realized. The Wetness variable and reflectance of the band ETM+7/Landsat 7 represent the initial status of vegetation of efficient form was verified, however had no sensitivity enough to eliminate the effect of soil type in the spectral response of the vegetation.