Predictive Models of Primary Tropical Forest Structure from Geomorphometric Variables Based on SRTM in the Tapajós Region, Brazilian Amazon

Abstract

Surveying primary tropical forest over large regions is challenging. Indirect methods of relating terrain information or other external spatial datasets to forest biophysical parameters can provide forest structural maps at large scales but the inherent uncertainties need to be evaluated fully. The goal of the present study was to evaluate relief characteristics, measured through geomorphometric variables, as predictors of forest structural characteristics such as average tree basal area (BA) and height (H) and average percentage canopy openness (CO). Our hypothesis is that geomorphometric variables are good predictors of the structure of primary tropical forest, even in areas, with low altitude variation. The study was performed at the Tapajós National Forest, located in the Western State of Pará, Brazil. Forty-three plots were sampled. Predictive models for BA, H and CO were parameterized based on geomorphometric variables using multiple linear regression. Validation of the models with nine independent sample plots revealed a Root Mean Square Error (RMSE) of 3.73 m2/ha (20%) for BA, 1.70 m (12%) for H, and 1.78% (21%) for CO. The coefficient of determination between observed and predicted values were r2 = 0.32 for CO, r2 = 0.26 for H and r2 = 0.52 for BA. The models obtained were able to adequately estimate BA and CO. In summary, it can be concluded that relief variables are good predictors of vegetation structure and enable the creation of forest structure maps in primary tropical rainforest with an acceptable uncertainty.

Drivers of metacommunity structure diverge for common and rare Amazonian tree species

“…Topographic variables obtained on the basis of the SRTM have been used to explain or predict the properties of vegetation [ 42 , 43 ]. These studies have helped in the understanding of the effects of topography on the distribution of different types of vegetation [ 44 – 48 ], floristic composition [ 12 , 49 ] and forest structure [ 14 , 50 ], particularly in tropical areas.…”

“…Efforts to understand these roles may help clarify the importance of different processes in maintaining the species diversity of these forests. In terms of the niche theory, variables representative of topography are likely to play an important role in local environmental conditions, which may determine the species diversity, functional and structural attributes and composition of tree communities [ 11 – 14 ]. One advantage of using topography in vegetation studies is that it can be assessed at large scales by remote sensing.…”

Wood Volume Estimation in a Semidecidual Seasonal Forest Using MSI and SRTM Data

“…In a study conducted in the Tapajós National Forest using the SRTM variables (altitude, slope, slope orientation, as well as the horizontal and vertical curvatures) to estimate the basal area, canopy opening and tree height, it was evident that altitude was the variable which gave the greatest explanatory capacity for the vegetation structure (Bispo et al, 2016).…”

“…In this context, studies have been successfully developed using remote sensing data associated with relief data (Bispo et al, 2016) or using the data provided by remote sensing to estimate the wood volume in different formations (Maack et al, 2016;Magnussen et al, 2018;Matasci et al, 2018), to predict the biomass and carbon (Fassnacht et al, 2018;Knapp et al, 2018;Rajashekar et al, 2018), to estimate the tree height (Cabo et al, 2018;Plowright et al, 2017), as well as the leaf area index (Varvia et al, 2018;Wang et al, 2017).…”

Multipropósito de Hymenaea courbaril L. em uma área de manejo florestal comunitário na Amazônia

“…O clima da região é do tipo Ami, com temperatura e precipitação média anual de 25,5 ºC e 1820 mm, respectivamente (ALVARES et al 2013). O solo predominante na região é do tipo Latossolo Amarelo Distrófico, profundos e bem drenados (Raimundo Junior et al 2015;Bispo et al 2016). A vegetação é classificada como Floresta Ombrófila Densa, caracterizando-se pela presença de árvores de grande porte e pela abundância de lianas lenhosas, palmeiras e epífitas (IBGE 2012).…”