Extent of Nontimber Resource Extraction in Tropical Forests: Accessibility to Game Vertebrates by Hunters in the Amazon Basin

Abstract

Extractive activities targeting a wide range of nontimber forest products ( NTFPs ) are ubiquitous in tropical forests, yet the extent of structurally intact forests in a given region affected by this form of cryptic disturbance is poorly documented. We conducted a basin‐wide geographic information system analysis of the nonmotorized accessibility of Amazonian NTFP extraction and estimated the proportion of the Amazon drainage basin within Brazil ( 3.74 million km 2 ) that can be accessed on foot from the nearest navigable river or functional road. We use a long‐term series of standardized line‐transect vertebrate censuses conducted throughout the region to illustrate the effects of physical accessibility on wildlife densities in terms of hunting pressure as a function of distance from the nearest point of access. Population abundance in large‐bodied, prime‐target species preferred by game hunters tended to increase at greater distances from the access matrix, whereas small‐bodied species ignored by hunters usually showed the reverse trend. In addition, we estimated the proportion of presumably inviolate core areas within nature, extractive, and indigenous reserves of Brazilian Amazonia that are prohibitively remote and unlikely to be overhunted; for instance, only 1.16% of the basin‐wide area is strictly protected on paper and is reasonably safe from extractive activities targeted to game vertebrates and other valuable NTFPs. Finally, we discuss the concept of truly undisturbed wildlands in the last major tropical forest regions by distinguishing potentially overharvested areas from those that remain largely or entirely pristine and that maintain viable populations of a full complement of harvest‐sensitive species.

Detecting anthropogenic disturbance in tropical forests

“…Persistently overhunted areas that no longer retain a full complement of harvest-sensitive vertebrate species comprise a large fraction of the forestlands that appear to be intact [18]. For example, only 1.2% of the Brazilian Amazon basin is both strictly protected on paper and reasonably inaccessible (O9 km from the nearest access point) to subsistence hunting and extraction of other valuable nontimber products [19]. Detecting the effects of game harvest and many other nonstructural forms of forest disturbance still relies heavily on hard-won field studies that are unavoidably limited in scale.…”

Fingerprinting the impacts of global change on tropical forests

“…Access routes penetrate most surviving forest; for example, only 20% of Brazilian Amazonian forest is more than 9 km from the nearest navigable river or a road (Peres & Lake 2003). The total amount of bushmeat extracted may exceed 5 million tonnes annually (Fa et al 2002).…”

“…We know that increasing hunting pressure follows forest accessibility, usually logging (Peres & Lake 2003), and that newly accessible areas have extraction rates of between three and six times those of nearby inaccessible areas (Robinson et al 1999). Thus, we can make an initial estimate of changes in hunting pressure on the basis of (i) bushmeat extraction rates; (ii) the amount of forest cover; (iii) the area of forest degraded annually; and (iv) rates of extraction in newly accessible areas.…”

Bushmeat hunting changes regeneration of African rainforests

“…First, growing human populations in the tropics, rural and urban, increase the demand for meat [6,9]. Secondly, improved infrastructure, partly as a consequence of logging in remote forest areas and for the transportation of agricultural products to urban markets, facilitates the transportation of hunted animals from the forest to urban consumers [10,11]. Large frugivores may decline even in structurally intact forest reserves as a result of illegal hunting, and in extreme cases, the decline may lead to a forest empty of large vertebrates [12].…”