Assessing ALOS-2/PALSAR-2 Data's Potential in Detecting Forest Volume Losses from Selective Logging in a Section of the Tapajós National Forest

This study focuses on evaluating the unique capabilities of ALOS-2/PALSAR-2 (ALOS2) polarimetric images for detecting forest volume losses resulting from the selective logging process within a sustainable framework in the Tapajós National Forest (TNF), situated in the heart of the Brazilian Amazon. Specifically, two areas within TNF characterized by intensive logging activities, ranging between 27 m³ ha⁻¹ and 29 m³ ha⁻¹, were chosen as Annual Production Units (APUs). Each APU was logged during a distinct year: APU 2016 and APU 2017. Extracting attributes from ALOS2 images, encompassing backscatter properties (including algebraic calculations, band ratios, SAR vegetation indices, and texture measurements) and phase information (comprising entropy and alpha angle), this investigation aims to detect forest volume losses. This involves evaluating the disparities in pixel values between logged and unlogged regions. The analysis employs Wilcoxon's nonparametric test at a 95% confidence level to determine the statistical significance of the observed differences. The findings gleaned from ALOS2 data demonstrate robust performance. Among the considered attributes, the Radar Normalized Difference Vegetation Index (RNDVI) emerges as the most promising indicator for detecting forest volume losses attributed to degradation through selective logging. Notably, this effectiveness is consistent across both investigated areas, with a p-value of 0.003 for APU 2016 and 0.037 for APU 2017. Additionally, the cross-polarization ratio and the texture measure known as Contrast in HV polarization display significant potential. This study underscores ALOS2's efficacy in identifying forest volume losses arising from selective logging. The insights gained, particularly the prominence of RNDVI in degradation detection, offer valuable perspectives for monitoring and mitigating ecological impacts stemming from logging activities within intricate forest ecosystems

Land-cover gradients determine alternate drivers of mammalian species richness in fragmented landscapes

ContextUnderstanding habitat fragmentation is a critical concern for nature conservation and the focus of intense debate in landscape ecology. Resolving the uncertainty around the effects of habitat fragmentation on biodiversity remains an ongoing challenge that requires the successful delineation of multiple patch-landscape interactions.ObjectivesWe carried out a regional analysis on species richness of woodland mammals to determine the relative influence of structural, compositional and functional characteristics related to woodland habitat across different land-cover gradients.MethodsWe calculated the Edge-weighted Habitat Index, an area-weighted measure of functional connectivity that incorporates a mechanistic estimate of edge-effects, for interior woodland habitat. We compared its influence on mammalian species richness to that of increasing edge and patch density, landscape diversity, and a habitat-only model, in different contexts of matrix hostility across Northern England in the UK.ResultsOur results demonstrate the relevance of alternative drivers of species richness resulting from patch-landscape interactions across gradients of matrix hostility. Evidence is provided for positive and negative effects of increasing structural (edge density), functional (connected interior habitat) and compositional (landscape diversity) attributes, varying according to matrix type and intensity. Results were sensitive to dominant land-cover types in the matrix and the scale of observation.ConclusionThis study provides new insights into fragmentation effects on biodiversity and clarifies assumptions around the relative influence of structural, compositional and functional habitat characteristics on landscape-level species richness. We highlight the presence of thresholds, related to matrix hostility, that determine alternative drivers of species richness in woodland mammals. These drivers, and related thresholds, were sensitive to the scale of observation and landscape context. Landscape decisions aimed at promoting biodiversity should consider sources of matrix hostility and homogeneity at scales relevant to ecological processes of interest