Browsing by Author "Beirne, Christopher"

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    African forest elephant movements depend on time scale and individual behavior.
    (Scientific reports, 2021-06-16) Beirne, Christopher; Houslay, Thomas M; Morkel, Peter; Clark, Connie J; Fay, Mike; Okouyi, Joseph; White, Lee JT; Poulsen, John R
    The critically endangered African forest elephant (Loxodonta cyclotis) plays a vital role in maintaining the structure and composition of Afrotropical forests, but basic information is lacking regarding the drivers of elephant movement and behavior at landscape scales. We use GPS location data from 96 individuals throughout Gabon to determine how five movement behaviors vary at different scales, how they are influenced by anthropogenic and environmental covariates, and to assess evidence for behavioral syndromes-elephants which share suites of similar movement traits. Elephants show some evidence of behavioral syndromes along an 'idler' to 'explorer' axis-individuals that move more have larger home ranges and engage in more 'exploratory' movements. However, within these groups, forest elephants express remarkable inter-individual variation in movement behaviours. This variation highlights that no two elephants are the same and creates challenges for practitioners aiming to design conservation initiatives.
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    Expected carbon emissions from a rubber plantation in Central Africa
    (Forest Ecology and Management, 2021-01-15) Jong, Ying Wei; Beirne, Christopher; Meunier, Quentin; Mekui Biyogo, Andréana Paola; Ebang Mbélé, Alex; Stewart, Christopher G; Poulsen, John R
    The development of agriculture on degraded lands is increasingly seen as a strategy to boost food availability and economic productivity while minimizing environmental degradation and loss of forests. To understand the effects of agricultural production on forest carbon, we quantify the aboveground carbon (AGC) of a degraded forest in northeast Gabon (the Olam Rubber Gabon concession) designated for development to a rubber plantation. Combining field measurements from 19 1-ha tree plots and aerial LiDAR, we estimate forest AGC stocks and emissions under four development scenarios: no development, 30-year rubber rotation, extended rubber rotation (replanting of plantation in stages at 30 and 40 years), and 30-year oil palm rotation. On average, the degraded forest in the study area stored 123.8 Mg C ha−1, a mean AGC lower than the Gabon average (141.6 Mg C ha−1) but substantially higher than the 75 Mg C ha−1 threshold recommended by the High Carbon Stock protocol. Converting secondary forest to plantation might incur high environmental opportunity costs from lost carbon sequestration through forest succession and growth. In this study, we estimate that a rubber plantation can sequester similar amounts of AGC as secondary forest by the end of a 30-year rotation; however, the time-averaged AGC of regenerating secondary forests under no development would be 184% higher than a mature rubber plantation with a 30-year rotation, 169% higher than an extended rubber rotation, and 512% higher than a 30-year oil palm rotation. When degraded forest is developed for agriculture, measures should be taken to avoid emissions and prolong carbon retention. We specifically estimate carbon retention from extended harvest rotations and conserving high carbon value areas as set-asides and highlight recommendations from the literature such as minimizing soil disturbance and creating rubber timber products (e.g. furniture). To minimize carbon emissions from agriculture, crop plantation area should be minimized at national and regional scales in highly forested countries, and new plantations should be coupled explicitly with effective forest restoration actions, through suitable regulation and planning, to mitigate or compensate for their climate and biodiversity impacts.
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    Forest elephant movement and habitat use in a tropical forest-grassland mosaic in Gabon.
    (PloS one, 2018-01) Mills, Emily C; Poulsen, John R; Fay, J Michael; Morkel, Peter; Clark, Connie J; Meier, Amelia; Beirne, Christopher; White, Lee JT
    Poaching of forest elephants (Loxodonta cyclotis) for ivory has decimated their populations in Central Africa. Studying elephant movement can provide insight into habitat and resource use to reveal where, when, and why they move and guide conservation efforts. We fitted 17 forest elephants with global positioning system (GPS) collars in 2015 and 2016 in the tropical forest-grassland mosaic of the Wonga Wongué Presidential Reserve (WW), Gabon. Using the location data, we quantified movement distances, home ranges, and habitat use to examine the environmental drivers of elephant movements and predict where elephants occur spatially and temporally. Forest elephants, on average, traveled 2,840 km annually and had home ranges of 713 km2, with males covering significantly larger home ranges than females. Forest elephants demonstrated both daily and seasonal movement patterns. Daily, they moved between forest and grassland at dawn and dusk. Seasonally, they spent proportionally more time in grassland than forest during the short-wet season when grasses recruit. Forest elephants also traveled faster during the short-wet season when fruit availability was greatest, likely reflecting long, direct movements to preferred fruiting tree species. Forest elephants tended to select areas with high tree and shrub density that afford cover and browse. When villages occurred in their home ranges elephants spent a disproportionate amount of time near them, particularly in the dry season, probably for access to agricultural crops and preferred habitat. Given the importance of the grassland habitat for elephants, maintenance of the forest-grassland matrix is a conservation priority in WW. Law enforcement, outreach, and education should focus on areas of potential human-elephant conflict near villages along the borders of the reserve. GPS-tracking should be extended into multi-use areas in the peripheries of protected areas to evaluate the effects of human disturbance on elephant movements and to maintain connectivity among elephant populations in Gabon.