Time filter

Source Type

Mitchard E.T.A.,University of Edinburgh | Saatchi S.S.,Jet Propulsion Laboratory | White L.J.T.,Agence Nationale des Parcs Nationaux | White L.J.T.,University of Stirling | And 13 more authors.
Biogeosciences | Year: 2012

Spatially-explicit maps of aboveground biomass are essential for calculating the losses and gains in forest carbon at a regional to national level. The production of such maps across wide areas will become increasingly necessary as international efforts to protect primary forests, such as the REDD+ (Reducing Emissions from Deforestation and forest Degradation) mechanism, come into effect, alongside their use for management and research more generally. However, mapping biomass over high-biomass tropical forest is challenging as (1) direct regressions with optical and radar data saturate, (2) much of the tropics is persistently cloud-covered, reducing the availability of optical data, (3) many regions include steep topography, making the use of radar data complex, (5) while LiDAR data does not suffer from saturation, expensive aircraft-derived data are necessary for complete coverage. We present a solution to the problems, using a combination of terrain-corrected L-band radar data (ALOS PALSAR), spaceborne LiDAR data (ICESat GLAS) and ground-based data. We map Gabon's Lopé National Park (5000 km2) because it includes a range of vegetation types from savanna to closed-canopy tropical forest, is topographically complex, has no recent contiguous cloud-free high-resolution optical data, and the dense forest is above the saturation point for radar. Our 100 m resolution biomass map is derived from fusing spaceborne LiDAR (7142 ICESat GLAS footprints), 96 ground-based plots (average size 0.8 ha) and an unsupervised classification of terrain-corrected ALOS PALSAR radar data, from which we derive the aboveground biomass stocks of the park to be 78 Tg C (173 Mg C ha-1). This value is consistent with our field data average of 181 Mg C ha-1, from the field plots measured in 2009 covering a total of 78 ha, and which are independent as they were not used for the GLAS-biomass estimation. We estimate an uncertainty of ± 25% on our carbon stock value for the park. This error term includes uncertainties resulting from the use of a generic tropical allometric equation, the use of GLAS data to estimate Lorey's height, and the necessity of separating the landscape into distinct classes. As there is currently no spaceborne LiDAR satellite in operation (GLAS data is available for 2003-2009 only), this methodology is not suitable for change-detection. This research underlines the need for new satellite LiDAR data to provide the potential for biomass-change estimates, although this need will not be met before 2015. © 2012 Author(s).


Schuttler S.G.,University of Missouri | Philbrick J.A.,University of Missouri | Jeffery K.J.,Agence Nationale des Parcs Nationaux | Jeffery K.J.,University of Stirling | And 2 more authors.
PLoS ONE | Year: 2014

Spatial patterns of relatedness within animal populations are important in the evolution of mating and social systems, and have the potential to reveal information on species that are difficult to observe in the wild. This study examines the fine-scale genetic structure and connectivity of groups within African forest elephants, Loxodonta cyclotis, which are often difficult to observe due to forest habitat. We tested the hypothesis that genetic similarity will decline with increasing geographic distance, as we expect kin to be in closer proximity, using spatial autocorrelation analyses and Tau Kr tests. Associations between individuals were investigated through a non-invasive genetic capture-recapture approach using network models, and were predicted to be more extensive than the small groups found in observational studies, similar to fission-fusion sociality found in African savanna (Loxodonta africana) and Asian (Elephas maximus) species. Dung samples were collected in Lopé National Park, Gabon in 2008 and 2010 and genotyped at 10 microsatellite loci, genetically sexed, and sequenced at the mitochondrial DNA control region. We conducted analyses on samples collected at three different temporal scales: a day, within six-day sampling sessions, and within each year. Spatial autocorrelation and Tau Kr tests revealed genetic structure, but results were weak and inconsistent between sampling sessions. Positive spatial autocorrelation was found in distance classes of 0-5 km, and was strongest for the single day session. Despite weak genetic structure, individuals within groups were significantly more related to each other than to individuals between groups. Social networks revealed some components to have large, extensive groups of up to 22 individuals, and most groups were composed of individuals of the same matriline. Although fine-scale population genetic structure was weak, forest elephants are typically found in groups consisting of kin and based on matrilines, with some individuals having more associates than observed from group sizes alone. © 2014 Schuttler et al.


PubMed | British Petroleum, Agence Nationale des Parcs Nationaux, CNRS Center of Evolutionary and Functional Ecology and Behavioral Ecology and Sociobiology Unit
Type: Letter | Journal: Current biology : CB | Year: 2016

Parasites are sometimes capable of inducing phenotypic changes in their hosts to improve transmission [1]. Toxoplasma gondii, a protozoan that infects a broad range of warm-blooded species, is one example that supports the so-called parasite manipulation hypothesis: it induces modifications in rodents olfactory preferences, converting an innate aversion for cat odor into attraction and probably favoring trophic transmission to feline species, its only definitive hosts [2]. In humans, T. gondii induces behavioral modifications such as personality changes, prolonged reaction times and decreased long-term concentration [3]. However, modern humans are not suitable intermediate hosts because they are no longer preyed upon by felines. Consequently, behavioral modifications in infected people are generally assumed to be side effects of toxoplasmosis or residual manipulation traits that evolved in appropriate intermediate hosts. An alternative hypothesis, however, states that these changes result from parasite manipulative abilities that evolved when human ancestors were still under significant feline predation [3,4]. As such, T. gondii also alters olfactory preferences in humans; infected men rate cat urine, but not tiger urine, as pleasant while non-infected men do not [5]. To unravel the origin of Toxoplasma-induced modifications in humans, we performed olfactory tests on a living primate still predated by a feline species. We found in our closest relative, the chimpanzee (Pan troglodytes troglodytes), that Toxoplasma-infected (TI) animals lost their innate aversion towards the urine of leopards (Panthera pardus), their only natural predator. By contrast, we observed no clear difference in the response of TI and Toxoplasma-non-infected (TN) animals towards urine collected from other definitive feline hosts that chimpanzees do not encounter in nature. Although the adaptive value of parasitically induced behavior should be assessed carefully, we suggest that the behavioral modification we report could increase the probability of chimpanzee predation by leopards for the parasites own benefit. This possible parasite adaptation would hence suggest that Toxoplasma-induced modifications in modern humans are an ancestral legacy of our evolutionary past.


PubMed | CIFOR, Jardin Botanico Joaquin Antonio Uribe, Red para la Mitigacion y Adaptacion al Cambio Climatico de la UNAD, Herbario Universitario and 63 more.
Type: | Journal: Scientific reports | Year: 2017

Tropical forests are global centres of biodiversity and carbon storage. Many tropical countries aspire to protect forest to fulfil biodiversity and climate mitigation policy targets, but the conservation strategies needed to achieve these two functions depend critically on the tropical forest tree diversity-carbon storage relationship. Assessing this relationship is challenging due to the scarcity of inventories where carbon stocks in aboveground biomass and species identifications have been simultaneously and robustly quantified. Here, we compile a unique pan-tropical dataset of 360 plots located in structurally intact old-growth closed-canopy forest, surveyed using standardised methods, allowing a multi-scale evaluation of diversity-carbon relationships in tropical forests. Diversity-carbon relationships among all plots at 1ha scale across the tropics are absent, and within continents are either weak (Asia) or absent (Amazonia, Africa). A weak positive relationship is detectable within 1ha plots, indicating that diversity effects in tropical forests may be scale dependent. The absence of clear diversity-carbon relationships at scales relevant to conservation planning means that carbon-centred conservation strategies will inevitably miss many high diversity ecosystems. As tropical forests can have any combination of tree diversity and carbon stocks both require explicit consideration when optimising policies to manage tropical carbon and biodiversity.


News Article | February 20, 2017
Site: www.eurekalert.org

Forest elephants living in an area that had been considered a sanctuary in the Central African country of Gabon are rapidly being picked off by illegal poachers, who are primarily coming from the bordering country of Cameroon. Researchers reporting in Current Biology on February 20 found that the forest elephant population in Gabon has dropped by more than 80 percent in a decade--a loss of about 25,000 elephants. "Because Gabon is thought to hold the largest remaining population of forest elephants, the implication is that forest elephants are in even more trouble than previously believed," says John Poulsen of Duke University and the Agence Nationale des Parcs Nationaux in Gabon. "With less than 100,000 elephants across all of Central Africa, the subspecies is in danger of extinction if governments and conservation agencies do not act fast. "We can no longer assume that apparently large and remote protected areas will conserve species--poachers will go anywhere that a profit can be made," he adds. "A corollary of this is that cross-border poaching is a major threat to species protection, and bilateral and multilateral efforts are essential for conservation. Species cross borders, and so do poachers." The researchers estimated the number of elephants in the forest in 2014 using established methods based on surveys of elephant dung. They then compared population size estimates for the year 2014 to estimates that had been calculated in the same way in 2004. Poulsen says they were not surprised to find that forest elephants had declined in recent years. But they were surprised to see that the forest elephants had suffered so much in just ten years' time. The researchers say the most important step to saving forest elephants is to reduce the demand for ivory. "China's recently announced ban of domestic ivory trade will help enormously, if it is effectively implemented," he says. "The international community needs to put pressure on all remaining nations that allow the trade so that all legal trade is stopped. We need conservation funds and political will to put a stop to the slaughter." The researchers also advocate for recognizing forest elephants as a distinct species, separate from African savanna elephants. Such a distinction is supported by genetic and morphological evidence and would help to draw attention to the forgotten forest elephants. Despite the findings, Poulsen says he is optimistic that forest elephants will survive, although they will most likely exist only in restricted areas within well-protected national parks. Their decline will surely be felt throughout the forest and beyond. "Elephants are ecosystem engineers that play major roles in seed dispersal, nutrient cycling, and browsing and damage to vegetation," Poulsen says. "We have very little idea about how the removal of elephants from large extents of Central African forest is going to alter forest composition and structure, and thus the ecosystem services that the forests provide." Current Biology (@CurrentBiology, published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit: http://www. . To receive Cell Press media alerts, contact press@cell.com.


News Article | February 20, 2017
Site: news.yahoo.com

Miami (AFP) - Poachers are killing elephants for their ivory at an alarming rate in the central African nation of Gabon, leading to a loss of 80 percent of the population in the last decade. Some 25,000 elephants have been slaughtered in Minkebe National Park, an area that had been considered a sanctuary, said the report in the journal Current Biology. "Because Gabon is thought to hold the largest remaining population of forest elephants, the implication is that forest elephants are in even more trouble than previously believed," said researcher John Poulsen of Duke University and the Agence Nationale des Parcs Nationaux in Gabon. "With less than 100,000 elephants across all of Central Africa, the subspecies is in danger of extinction if governments and conservation agencies do not act fast." The poachers are primarily coming into Gabon from the bordering country of Cameroon, the report said. "We can no longer assume that apparently large and remote protected areas will conserve species -- poachers will go anywhere that a profit can be made," said Poulsen. To estimate the number of elephants in the forest in 2014, researchers surveyed dung in the forest. They then compared population size estimates for 2014 to estimates calculated in the same way in 2004. A key driver of the poaching is demand for ivory, which must be curtailed, researchers said. "China's recently announced ban of domestic ivory trade will help enormously, if it is effectively implemented," said Poulson. "The international community needs to put pressure on all remaining nations that allow the trade so that all legal trade is stopped." Another strategy is to recognize forest elephants as a distinct species from African savanna elephants, to draw attention to their often forgotten plight. Gabon has taken steps to protect elephants since 2011, elevating forest elephants' conservation status to "fully protected," creating a National Park Police force, doubling the national park agency's budget, and becoming the first African nation to burn all confiscated ivory, the report said. However, Poulsen said more action is needed, such as coordinated international law enforcement to prosecute wildlife criminals and new multinational protected areas. "The clock is ticking," he said.


PubMed | Environment Society of Oman, University of Pretoria, Humpback Whale Project Humpback Whale Institute, New York University and 7 more.
Type: | Journal: Molecular ecology | Year: 2016

Elucidating patterns of population structure for species with complex life histories, and disentangling the processes driving such patterns, remains a significant analytical challenge. Humpback whale (Megaptera novaeangliae) populations display complex genetic structures that have not been fully resolved at all spatial scales. We generated a data set of nuclear markers for 3575 samples spanning the seven breeding stocks and substocks found in the South Atlantic and western and northern Indian Oceans. For the total sample, and males and females separately, we assessed genetic diversity, tested for genetic differentiation between putative populations and isolation by distance, estimated the number of genetic clusters without a priori population information and estimated rates of gene flow using maximum-likelihood and Bayesian approaches. At the ocean basin scale, structure is governed by geographical distance (IBD P<0.05) and female fidelity to breeding areas, in line with current understanding of the drivers of broadscale population structure. Consistent with previous studies, the Arabian Sea breeding stock was highly genetically differentiated (F


Maxwell S.M.,University of California at Santa Cruz | Maxwell S.M.,Marine Conservation Institute | Breed G.A.,University of California at Santa Cruz | Nickel B.A.,University of California at Santa Cruz | And 9 more authors.
PLoS ONE | Year: 2011

Tractable conservation measures for long-lived species require the intersection between protection of biologically relevant life history stages and a socioeconomically feasible setting. To protect breeding adults, we require knowledge of animal movements, how movement relates to political boundaries, and our confidence in spatial analyses of movement. We used satellite tracking and a switching state-space model to determine the internesting movements of olive ridley sea turtles (Lepidochelys olivacea) (n = 18) in Central Africa during two breeding seasons (2007-08, 2008-09). These movements were analyzed in relation to current park boundaries and a proposed transboundary park between Gabon and the Republic of Congo, both created to reduce unintentional bycatch of sea turtles in marine fisheries. We additionally determined confidence intervals surrounding home range calculations. Turtles remained largely within a 30 km radius from the original nesting site before departing for distant foraging grounds. Only 44.6 percent of high-density areas were found within the current park but the proposed transboundary park would incorporate 97.6 percent of high-density areas. Though tagged individuals originated in Gabon, turtles were found in Congolese waters during greater than half of the internesting period (53.7 percent), highlighting the need for international cooperation and offering scientific support for a proposed transboundary park. This is the first comprehensive study on the internesting movements of solitary nesting olive ridley sea turtles, and it suggests the opportunity for tractable conservation measures for female nesting olive ridleys at this and other solitary nesting sites around the world. We draw from our results a framework for cost-effective protection of long-lived species using satellite telemetry as a primary tool. © 2011 Maxwell et al.

Loading Agence Nationale des Parcs Nationaux collaborators
Loading Agence Nationale des Parcs Nationaux collaborators