Multi‐temporal assessment of selective logging in the Brazilian Amazon using Landsat data

Abstract

Large-scale selective logging is a relatively new activity in the Amazon and its full consequences have yet to be evaluated. Impacts by selective logging alone have been estimated to increase approximately 4-7% of the annual carbon release from deforestation. In this research, visual interpretation and semi-automated remote sensing techniques were applied to identify and map areas of selective logging in tropical terra firme (upland) forests together with the correlated multiannual measurement results for 1992, 1996, and 1999, for the Brazilian Amazon. The research results indicate that selective logging is rapidly increasing in both intensity (regional) and area (basin-wide). By 1992, at least 5980 km 2 of forest had been logged. During the 1992During the -1996During the and 1996During the -1999 periods the area impacted expanded by an additional 10 064 km 2 , and 26 085 km 2 , respectively. Selective logging within protected areas increased more than twofold between 1992 and 1996, and more than fivefold between 1996 and 1999 in that region. We also estimated that at least 3689 km 2 had been actively logged in 1992, an additional 5107 km 2 , and 11 638 km 2 , had been logged in 1996 and 1999, and at least 10% of total logged forests detected in 1999 were previously logged in the period of analysis.

Detecting anthropogenic disturbance in tropical forests

“…Field validation of their study suggests a combined uncertainty of 11-14% in a logged area of O47 000 km 2 . These estimates echo those of previous studies indicating that selective logging affects an area that is comparable or greater than that completely clear-cut every year [7,8].…”

“…Field validation of their study suggests a combined uncertainty of 11-14% in a logged area of O47 000 km 2 . These estimates echo those of previous studies indicating that selective logging affects an area that is comparable or greater than that completely clear-cut every year [7,8].In another recent study in a smaller forest area of southern Amazonia surrounded by the recent expansion of soybean agriculture, Souza, Jr and collaborators [6] field tested another image-processing technique that holds great promise as a tool to map logging and fire-induced canopy damage. The technique relies on a gap fraction index (the Normalized Difference Fraction Index, NDFI) that combines the green and non-photosynthetic vegetation, soil and shade fractions derived from SMA to enhance the detection of log landings and skid trails, the spatial signature of selective logging [9].…”

“…Total area affected by deforestation (green circles), selective logging (red squares) and surface fires (blue diamonds) throughout Brazilian Amazonia during the past century. These estimates are based on a range of sources, including the annual deforestation statistics made available by INPE [5]; a conservative estimate of basin-wide logging disturbance [5,8,16]; and a conservative estimate of the area affected by surface wildfires [7,17].…”

Traditional shifting agriculture: tracking forest carbon stock and biodiversity through time in western Panama

“…Multi-year assessments using a time series of satellite imagery have been suggested as an adequate means of tracking complex land-cover dynamics that include clearing and regrowth. Such assessments increase the possibility of detecting small-scale intervention (Stone & Lefebvre, 1998;Asner et al, 2005;Broadbent et al, 2006;Matricardi et al, 2007), and by using sub-pixel information (Souza et al, 2003;Brandt & Townsend, 2006;Matricardi et al, 2010). Compelling research on selective logging has made use of methodologies that allow the extent of these activities to be quantified (Asner et al, 2004b;Souza et al, 2005a;Asner et al, 2006).…”

Using fuzzy cognitive maps to describe current system dynamics and develop land cover scenarios: a case study in the Brazilian Amazon

“…Accessibility contributed significantly towards stabilizing land prices, which indicates the gradual stabilization of land markets in old frontiers that are more accessible to local markets. Infrastructure contributed towards stabilizing accessibility similarly to its feedback with agro-pasture expansion, which indicates that deforestation can occur before infrastructure expansion as, for example, in logging activities in the region (Matricardi, Skole, Cochrane, Pedlowski, and Chomentowski 2007). Fire spots stabilized in a positive trend due to the contribution of agro-pasture expansion and dry season severity, even though the latter is less important.…”