Predicting aboveground forest biomass with topographic variables in human‐impacted tropical dry forest landscapes

Abstract

Topographic variables such as slope and elevation partially explain spatial variations in aboveground biomass (AGB) within landscapes. Human activities that impact vegetation, such as cattle grazing and shifting cultivation, often follow topographic features and also play a key role in determining AGB patterns, although these effects may be moderated by accessibility. In this study, we evaluated the potential to predict AGB in a rural landscape, using a set of topographical variables in combination with indicators of accessibility. We modeled linear and non‐linear relationships between AGB, topographic variables within the territorial boundaries of six rural communities, and distance to roads. Linear models showed that elevation, slope, topographic wetness index, and tangential curvature could explain up to 21% of AGB. Non‐linear models found threshold values for the relationship between AGB and diffuse insolation, topographic position index at 19 × 19 pixels scale and differentiated between groups of communities, improving AGB predictions to 33%. We also found a continuous and positive effect on AGB with increased distance from roads, but also a piecewise relationship that improves the understanding of intensity of human activities. These findings could enable AGB baselines to be constructed at landscape level using freely available data from topographic maps. Such baselines may be of use in national programs under the international policy Reducing Emissions from Deforestation and Forest Degradation.

The accuracy of species-specific allometric equations for estimating aboveground biomass in tropical moist montane forests: case study of Albizia grandibracteata and Trichilia dregeana

“…Within-stand variation of biomass for different tree species is related to tree architecture, growth strategies and its dynamic interplay with the biophysical environments [20][21][22]. The difference of TAGB across a forest landscape is mostly related to the variation in slope, elevation, and aspect [18,23]. Generally, tropical forests are known for their high diversity of woody plants.…”

How Socio-Economic Differences between Farmers Affect Forest Degradation in Western Mexico

“…Rain falls mainly during the summer months, and the mean annual precipitation between 2004 and 2012 was 950 mm, whereas the mean temperature for the same period was about 21 • C. In terms of human use, all suitable low lying level areas have been permanently converted to agriculture, which has been the case for many years. However, the wooded slopes, particularly in the TDF zone, are typically used for cycles of shifting cultivation and temporary grazing, and have been degraded as a result, as demonstrated by several studies of canopy cover using remote sensing [33,47,53]. In recent years, level areas at higher altitudes are increasingly being cleared of forest and converted into permanent agriculture or pasture, although this is in most cases illegal.…”

Estoque de carbono em paisagens tropicais fragmentadas

“…AGB) and changes in structure, through selective removal of certain species, while others find the opportunity to regenerate in human-dominated landscapes. Where human pressure is greater as a result of accessibility to roads and human settlements (Salinas-Melgoza et al, 2018), there is obviously more likelihood of direct or indirect impact on natural vegetation (Cincotta et al 2000, Luoga et al 2002, Mon et al 2012, Morales-Barquero et al 2015. Landscape-level processes are thus interacting with human activities and terrain factors to regulate biomass in tropical fragmented landscapes.…”

“…Elevation and slope are the most commonly considered topographic variables to forest structure (Salinas-Melgoza et al, 2018). Besides their interaction with human access, those factors are related to air temperature and solar radiation, which affect forest biomass through evapotranspiration rates (Homeier et al 2010, Sundqvist et al 2013).…”

“…Besides their interaction with human access, those factors are related to air temperature and solar radiation, which affect forest biomass through evapotranspiration rates (Homeier et al 2010, Sundqvist et al 2013). The effect of the aspect on forest structure has been well recognized, but in tropical areas, this does not usually play a key role in structuring vegetation (Gallardo-Cruz et al 2009;Salinas-Melgoza et al 2018). Solar radiation, that is, the amount of radiant energy received at a certain location varies not only with the amount of sunshine but with slopes, aspect, and adjacent topography (Wilson and Gallant 2000).…”