3 results on '"Luse Belanganayi, Basile"'
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2. Diel and annual rhythms of tropical stem size changes in the Mayombe forest, Congo Basin.
- Author
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Luse Belanganayi, Basile, Angoboy Ilondea, Bhely, Mbungu Phaka, Christophe, Laurent, Félix, Djiofack, Brice Y., Kafuti, Chadrack, Peters, Richard L., Bourland, Nils, Beeckman, Hans, and De Mil, Tom
- Subjects
WEATHER ,CARBON cycle ,TREE growth ,RHYTHM ,TROPICAL forests - Abstract
Introduction: The Congo Basin forests, a crucial global carbon sink, are expected to face increased challenges of climate change by 2027, with an expected temperature rise of 1.5°C above pre-industrial levels, accompanied by increased humidity conditions. However, studies that try to understand their functioning and untangle the species-specific responses about how weather conditions impact secondary growth dynamics are still rare. Methods: Here we present the results of a study on diel and annual stem growth in 17 trees, belonging to 11 most abundant species, both canopy and understory, in the Mayombe forest (Congo Basin) in the Democratic Republic of the Congo (DRC). We measured highly-resolved radial stem size variations and weather conditions, to comprehend the ongoing patterns of secondary growth and examine the potential influence of projected weather conditions on them. Results: We found that at the diel scale, trees probably grow mainly from 6pm to 9am, and that at the annual scale, they grow mainly during the rainy season, from October to May. Some trees grow year-round, while others stop growing for a period ranging from 1 to 4 months. This growth cessation typically occurs during the dry season from June to September. A generalized linear mixed-effect model revealed that annual radial stem growth is positively related to rainfall. Discussion: Our results suggest that trees in the study site have a significant potential to cope with the projected 1.5°C increase in global temperature and an additional 50 mm of local rainfall. Trees of the species T. superba exhibited improved growth under the projected scenarios. For the other tree species, no significant difference in growth was observed between the predicted and observed scenarios. We believe that much remains to be done to better understand the tree growth-climate interaction of the large variety of tree species in the Congo Basin. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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3. UAS imagery reveals new survey opportunities for counting hippos
- Author
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Linchant, Julie, Lhoest, Simon, Quevauvillers, Samuel, Lejeune, Philippe, Vermeulen, Cédric, Semeki Ngabinzeke, Jean, Luse Belanganayi, Basile, Delvingt, Willy, and Bouché, Philippe
- Subjects
Data Analysis ,Atmospheric Science ,Light ,Physiology ,Animal Types ,Marine and Aquatic Sciences ,lcsh:Medicine ,Reflection ,Wind ,Wildlife ,Meteorology ,Ornithology ,Rivers ,Clouds ,Surveys and Questionnaires ,Bird Flight ,Medicine and Health Sciences ,Animals ,lcsh:Science ,Animal Flight ,Artiodactyla ,Biological Locomotion ,Physics ,Electromagnetic Radiation ,Ecology and Environmental Sciences ,lcsh:R ,Organisms ,Classical Mechanics ,Biology and Life Sciences ,Eukaryota ,Aquatic Environments ,Bodies of Water ,Physical Sciences ,Earth Sciences ,Sunlight ,Solar Radiation ,lcsh:Q ,Zoology ,Research Article ,Freshwater Environments ,Environmental Monitoring - Abstract
Introduction The common hippopotamus Hippopotamus amphibius L. is a vulnerable species that requires efficient methods to monitor its populations for conservation purposes. Rapid evolution of civil drones provides new opportunities but survey protocols still need development. This study aims to determine the optimal flight parameters for accurate population estimates. A second objective is to evaluate the effects of three environmental factors: wind speed, sun reflection and cloud cover. Method We estimated the population of two main hippo schools (Dungu and Wilibadi II) located in Garamba National Park in Democratic republic of Congo. Eight observers reviewed 252 photos taken over the Dungu school, representing a total of 2016 experimental units. A detection rate and a level of certainty were associated with each experimental unit, and five parameters were related to each count: flight height, three environmental parameters (sun reflection on water surface, cloud cover, and wind speed), and observers’ experience. Results Flight height reduced the observers’ confidence in their detection ability, rather than the detection itself. For accurate counts of large groups an average height of 150 m was shown to be a good compromise between animal detection without zooming in and the area covered in one frame. Wind speed had little influence on the counts, but it affected the performance of the UAS. Sun reflection reduced the detection rate of hippos and increased level of certainty, while cloud cover reduced detection rates slightly. Therefore, we recommend flying when the sun is still low on the horizon and when there is little cloud, or when cloud cover is light and even. This last point reinforces our recommendation for flights early in the day. The counts also showed large differences between groups of inexperienced and experienced observers. Experienced observers achieved better detection rates and were generally more confident in their detection. Experienced observers detected 86.5% of the hippos on average (confidence interval = ±0.76%). When applied to data from the second site, the detection was 84.3% (confidence interval = ±1.84%). Two correction factors were then calculated, as the inverse of the detection rate, based on the estimated number of hippos present during one flight (Factor 1) or in the general population respectively (Factor 2). Factor 2 especially was consistent with previous studies using traditional aerial counts (1.22 vs 1.25). Factor 2 was found to be appropriate for use by experienced observers. These results confirm the use of correction factor 2 for hippo surveys, regardless of the study site, as it accounts for hippo behavior. Optimum counting and cost efficiency were achieved with two trained observers counting 7 pictures. Conclusion This study is a promising approach for routine surveys of the hippopotamus which is a species usually ignored in wildlife counts. Drone technology is expected to improve rapidly; therefore UAS could become a very useful and affordable survey tool for other species requiring specific monitoring.
- Published
- 2018
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