Peters C.M.,New York Botanical Garden |
Thammavong B.,National Agriculture and Forestry Research Institute NAFRI |
Mekaloun B.,National Agriculture and Forestry Research Institute NAFRI |
Phearoom N.,WWF Cambodia |
And 2 more authors.
Forest Ecology and Management
We studied the annual stem growth of six species of wild rattans over a 4-year period in permanent plots located in Prek Thnot, Cambodia and Ban Sopphouane, Laos. The rattan species studied in Cambodia included Calamus palustris, C. tetradactylus, C. viminalis, Myrialepis paradoxa, and Plectocomia pierreana; C. solitarius was studied in Laos. We collected a total of 1206 growth measurements over the 4-year period. There were significant differences in growth between species, with the M. paradoxa and P. pierreana exhibiting the fastest growth (229.7±29.8cmyear-1 and 221.5±17.9cmyear-1, respectively) and C. tetradactylus exhibiting the slowest growth (78.3±4.3cmyear-1). Stem height and measurement year also had a significant effect on growth. Growth projections revealed that the time required to produce a commercial cane varied from 2 to 8years. Analyses of sample size requirements using group means and variances showed that a reasonable estimate of wild rattan growth can be obtained by marking and measuring 50-60 sample plants, over half of which are of pre-commercial size. Using growth rates to guide the annual harvest of rattan in Southeast Asia would be a major step forward to insure a continual supply of this valuable non-timber resource. © 2013 Elsevier B.V. Source
Ryan G.E.,WWF Cambodia |
Ryan G.E.,University of Melbourne |
Dove V.,Murdoch University |
Dove V.,Apple Inc |
And 2 more authors.
Riverine Irrawaddy dolphin populations are critically endangered and much uncertainty exists over the population status in the Mekong River of northeast Cambodia and southern Lao People's Democratic Republic (Lao PDR). We conducted 11 surveys over three years to estimate abundance at each survey as well as survival and the probability of individuals becoming unavailable for detection between surveys. We utilized novel mark-resight estimators to account for the detection process in estimating these parameters. Annual survival was 0.977 (0.040 SE) and movement in (0.060) and out (0.018) of an observable state was low. We estimated abundance at 84.5 (95% CI=77.9-91.2) with little change over our surveys. We also estimated recruitment and population growth rate for the marked, and presumably older, individuals by estimating seniority using a reverse-time model. Seniority was estimated at 0.999 (0.028 SE), recruitment at 0.001 and population growth rate at 0.978. Although the population size appears to be stable, we believe this represents the slow disappearance of a long-lived animal with no recruitment. Along with the isolated nature of the population and reduced population size as compared to historical estimates, we believe this population is in serious threat of extirpation. We believe there may be as few as 7 or 8 animals in Lao PDR and that the species is at risk of extinction there in the short-term. Although recent management actions (e.g., outlawing of explosive fishing and some restriction on the use of gill-nets) have likely been beneficial we believe identifying population goals to work towards, identifying additional management actions to improve recruitment, and designing the survey methods to best estimate the success of these actions is needed. Copyright: © 2011 Ryan et al. Source
Beasley I.,James Cook University |
Pollock K.,Murdoch University |
Jefferson T.A.,Clymene Enterprises |
Arnold P.,Museum of Tropical Queensland |
And 4 more authors.
Marine Mammal Science
The population of Irrawaddy dolphins that occupies the Mekong River in southern Lao People's Democratic Republic and Cambodia is classified as Critically Endangered by the IUCN. Based on capture-recapture of photo-identified individuals, we estimated that the total population numbered 93 ± SE 3.90 individuals (95% CI 86-101), as of April 2007. The combined photo-identification and carcass recovery program undertaken from 2001 to 2007 established that the Irrawaddy dolphin population inhabiting the Mekong River has reached a critical point with regards to its continued survival, where immediate research and management actions are required to greatly reduce adult mortality, and establish the cause of newborn mortality. In addition, community consultation is required to initiate, and evaluate, urgently required conservation measures. An ongoing well-designed combined program of abundance estimation (i.e., photo-identification) and carcass recovery is required to monitor total population size and mortality rates, to inform and evaluate management initiatives. The conclusions of this paper are likely generic to river dolphin populations, particularly where photo-identification is possible. © 2012 by the Society for Marine Mammalogy. Source