Rapid evaluation of threats to biodiversity: human footprint score and large vertebrate species responses in French Guiana

Abstract

Although there is an extensive literature demonstrating the impact of human activities on both species extinction risk and local ecological processes, the methodological tools that allow for the visualization and quantification of the intensity of the observed and forthcoming impacts are lacking. Here we propose a Footprint index for French Guiana, (northern Atlantic coast of South America) which sums up the expected and proven disturbances on biodiversity. The index was developed by superimposing geographical and human data, including human population densities, land use, settlements and camps, mining and forest activities, tracks, roads and rivers. The relevance of the index as a general measure of anthropic impact on large terrestrial fauna was estimated by investigating the structure of the large terrestrial vertebrate assemblages, including primates, large frugivorous birds, rodents and ungulates, in relation to the extent of disturbances. The abundance of large terrestrial fauna was assessed using the line-transect sampling method in 34 forest sites facing different disturbance levels, including hunting, logging and B. de Thoisy (&) Association Kwata ''Study and Conservation of French Guianan Wildlife'', BP 672, fragmentation, and consequently different footprint scores. A Self Organizing Map was used to combine species abundances and disturbance scores. It allowed us to rank species in accordance to their sensitivity towards disturbances, identifying the response of fauna to different concomitant threats. The index provided correct identification of sites with similar threats which proves it is a relevant estimator of human disturbance. In addition, the richness of animal communities and abundances of several seed dispersers and predators were negatively correlated to the index (e.g. large monkeys and frugivorous birds, r 2 = 0.49, P \ 0.0001 and r 2 = 0.48, P \ 0.0001, respectively), indicating its reliability in identifying areas where animal communities are disturbed. The index could, therefore, constitute a useful tool to identify areas where ecological processes supported by those species are expected to be disrupted, and where they are already disrupted. Furthermore, the footprint index can deal with lack of field data or with only partially valid information, and so may directly help land managers forecast and, hopefully, mitigate forthcoming impacts resulting from the development of human activities.

Mapping a Knowledge-Based Malaria Hazard Index Related to Landscape Using Remote Sensing: Application to the Cross-Border Area between French Guiana and Brazil

“…In a second step, such an index should be combined with geographic layers characterizing the vector habitats and the human footprint [51] in order to consider which areas are actually associated with the presence of vectors and humans, and to what extent. More generally, it is worth noting that such a hazard index is only a component of a global and integrated risk index that should take into account spatialized information layers related to the presence and density of vectors and human populations, the presence of the parasite and the parasite load in the human populations, the human immunity level and genetic susceptibility, and climatic and behavioral factors.…”

Determinants of fish assemblage structure in Mount Itoupé mountain streams (French Guiana)

“…These rare and original mountain ecosystems hence deserve more attention and need to be preserved from the multiple human disturbances that affect neotropical freshwater ecosystems (Hammond et al, 2007;Barletta et al, 2010;de Thoisy et al, 2010;Mol et al, 2012). In addition to the faunistic inventory, this work also permitted for the first time to investigate the hierarchical screening of the fish fauna (Jackson et al, 2001) in the Guiana Shield, and to show that biogeographical and regional scale determinants are more influent than the local habitat in the mountain streams.…”

Assessing Sampling Biases in Logging Impact Studies in Tropical Forests

“…Longitudinal studies can compare the same forest before and after logging harvests and can explicitly control for several environmental gradients within sites [56], which are typically subject to inherent Mongabay.com Open Access Journal -Tropical Conservation Science Vol.6 (1): [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]2013 Tropical Conservation Science | ISSN 1940-0829 | Tropicalconservationscience.org 25 systematic biases in the choice of logging areas by operators (e.g., logged-over forest tends to be associated with higher pre-logging basal areas). Most studies reviewed here lacked before-and-after data, so researchers should meet the assumption of forest homogeneity in order to compare data within and between studies [69].…”

“…hunting, clear-cutting, and fire - [24][25]) can affect results and their interpretation. The history of logging disturbance (e.g.…”