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See detailEnrichment of logging gaps with moabi (Baillonella toxisperma Pierre) in a Central African rain forest
Doucet, Jean-Louis ULg; Kouadio, Y. L.; Monticelli, D. et al

in Forest Ecology & Management (2009), 258(11), 2407-2415

Studies of regeneration in African rain forests suggest that without silvicultural treatments, natural succession in logging gaps may not result in the establishment of timber species. In this paper we ... [more ▼]

Studies of regeneration in African rain forests suggest that without silvicultural treatments, natural succession in logging gaps may not result in the establishment of timber species. In this paper we present the results of an experimental enrichment planting with moabi (Baillonella toxisperma Pierre), a valuable and important timber species harvested in Central Africa. Although forest gaps are generally considered as favourable for the regeneration of this species, a survey conducted in a forest concession in southeastern Cameroon provided an estimate of only 12.7 seedlings ha 1, suggesting that the species was, in fact, poorly represented in logging gaps within the study area. To further investigate the dynamics of the moabi in logging gaps, 795 seeds were sown in 15 logging gaps and 410 nursery-raised seedlings were planted in 15 other gaps. A biannual monitoring program over a 30-month period showed a lower survival rate for seedlings from sowing (75.9%) compared to that of nursery-raised seedlings (95.3%). Planted seedlings reached on average 229.3 cm whereas seedlings from sowing were 167.5 cmtall, with the observed difference roughly corresponding to the average height of the nursery-raised seedlings at the time they were introduced to the logging gaps. After 30 months, the diameters of planted seedlings (16.8 mm) were also greater than those of the directly sown individuals (12.5 mm). Forest gap characteristics significantly influenced the growth of the plants. Factors accounting for the differences were total solar radiation, the soil content of coarse sand, the topographic position of the gap, the vegetation cover and the density of Macaranga spp. Whilst total solar radiation had a positive influence on growth, the remaining factors had impacted growth negatively. A streamlined technique was tested by planting 7 seedlings in 250 gaps. Without additional site maintenance, 29.3% of the moabi seedlings emerged naturally from the competing vegetation after 24 months. With biannual maintenance some 89.4% of seedlings became successfully established. Clearance operations had no significant influence on the height of plants whilst plant diameter was greater in cleared gaps. The total cost of the enrichment technique was 5.5 EUR per gap without maintenance and 7.5 EUR per gap with a single maintenance measure. Whilst long-term monitoring is needed, this study suggests a high survival rate of moabi introduced in logging gaps, and a growth rate 10 times higher than previously reported under canopy cover. These findings, combined with the low costs of the enrichment technique, support the use of silvicultural measures in logging gaps to restore the forest. [less ▲]

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See detailCommunity hunting in logging concessions: towards a management model for Cameroon’s dense forests
Vermeulen, Cédric ULg; Julve Larrubia, C.; Doucet, Jean-Louis ULg et al

in Biodiversity & Conservation (2009), 18(10), 2705-2718

In central Africa, commercial poaching and local village hunting are still two major issues that logging companies must address through the implementation of effective management plans in order to certify ... [more ▼]

In central Africa, commercial poaching and local village hunting are still two major issues that logging companies must address through the implementation of effective management plans in order to certify their concessions. However, current problems in developing suitable hunting management schemes for dense tropical forests arise from (1) the difficulty associated with setting quotas which take into account indiscriminate local hunting practices (e.g. snare trapping) and the ill-defined modes of resource appropriation by local populations, (2) the difficulty associated with evaluating the effect of illegal hunting, i.e. poaching, and (3) the relative complexity of the main available model. To overcome this, we propose to develop alternative management models where village hunting is planned along the same lines as existing logging operation models, through the implementation of a system of spatio-temporal rotation of hunting areas. In practice, the logging concession, initially divided into annual logging areas, is divided into similar annual hunting areas (AHAs), which are opened to hunting during the year preceding the logging operations. A depletion of the wildlife stock is expected within the annually opened hunting areas, but the model assumes a progressive re-colonization of the depleted AHA in subsequent years from neighbouring ones. In this paper, an empirical model of such a controlled hunting system employing spatio-temporal rotation of hunting areas is tested within a Forestry Management Unit (FMU) covering 47,585 ha in the Dja region, in south-east Cameroon. The model, based on large forest areas, seems particularly well adapted to Cameroon’s dense forests because it fits within the existing legal framework of Community-Managed Zones of Hunting Interest (CMZHI) and is aligned with current logging concession operations. Preliminary results suggest that sustainable hunting can be achieved in the FMU, provided a management scheme of AHAs is strictly enforced through effective stakeholder commitment. [less ▲]

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See detailAdult Survival Of Tropical Roseate Terns Breeding On Aride Island, Seychelles, Western Indian Ocean
Monticelli, D.; Ramos, Ja.; Guerreiro-Milheiras, Sa. et al

in Waterbirds (2008), 31(3), 330-337

Survival of tropical Roseate Terns (Sterna dougallii) from the western Indian Ocean was modeled using a capture-mark-recapture dataset of 102 breeding adults ringed and resighted on Aride Island ... [more ▼]

Survival of tropical Roseate Terns (Sterna dougallii) from the western Indian Ocean was modeled using a capture-mark-recapture dataset of 102 breeding adults ringed and resighted on Aride Island, Seychelles, from 2002 to 2007. The effect of covariates reflecting oceanographic conditions and resighting effort was also examined during the modeling. A time-invariant survival rate was best supported by our data, with annual adult survival estimated at 0.807 ± 0.033 (SE). Resighting probability was found to be influenced by sea-surface temperature (SST) anomalies, as expressed by the mean Indian Ocean Dipole mode index recorded during the nonbreeding period. Years of higher SST in the western part of the Indian Ocean in September-April (8 months) corresponded to a lower probability of resighting adults at the colony during the breeding season (May-August), which may be related to a tendency for some adults to refrain from breeding in less favorable years. Comparing our results with temperate studies, Roseate Terns breeding on Aride were found to exhibit similar survival estimates. Consequently, this study does not support the hypothesis that tropical Roseate Terns may counterbalance their lower fecundity (clutch size and breeding success) compared to their temperate and northern-hemisphere counterparts (Europe, North America, Caribbean) by relatively higher survival rates. [less ▲]

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See detailInfluence of woodland cover on habitat selection and reproductive parameters of tropical roseate terns: implications for colony management
Monticelli, D.; Ramos, J. A.; Doucet, Jean-Louis ULg

in Endangered Species Research (2008), 4

We examined the effect of vegetation structure, in particular canopy closure, on colony site occupancy, nesting densities, and reproductive parameters of roseate terns Sterna dougallii breeding in a ... [more ▼]

We examined the effect of vegetation structure, in particular canopy closure, on colony site occupancy, nesting densities, and reproductive parameters of roseate terns Sterna dougallii breeding in a Pisonia grandis dominated woodland on Aride Island, Seychelles, western Indian Ocean. Long-term observations (1995 to 2006) revealed that areas with high vegetation density and canopy cover (>50%) were abandoned, in favour of nearby more open forest areas, such as clearings. The attractiveness of a forest clearing (0 to 25% canopy cover) to breeding birds was also largely supported by experimental manipulation of vegetation density in 2004. Most birds moved from areas under canopy cover to experimentally cleared plots, where they nested at higher densities and had a higher probability of successfully fledging a chick. However, some individuals remained in their original areas, despite their greater canopy cover, and had a lower fledging success. This site tenacity is presumably explained by an imprinting process leading some birds to breed in successive years in the same, familiar locations, despite their nest-sites having become sub-optimal for fledging success. Roseate terns choosing a nest site in woodland on Aride must trade off the need for some cover, offering protection from the sun, against the need for easy access through gaps in the canopy to fly to and from their nests. A suitable nest-site should also minimize chick/parent infestation by ticks and mortality caused by contamination of feathers with the sticky fruits of Pisonia grandis. We suggest that, when they are not formed naturally, small artificial forest clearings within the usual breeding area are likely to be attractive for roseate terns and may result in enhanced colony productivity. These findings may be applicable to other seabird colonies (e.g. sooty terns) found under forest cover on oceanic islands throughout the Indo-Pacific region. [less ▲]

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See detailChoice of a suitable E-nose output variable for the continuous monitoring of an odour in the environment
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Monticelli, D. et al

in Gardner, J.; Persaud, K. (Eds.) Electronic noses and olfaction 2000. Proceedings of abstracts ISOEN 2000. (2000)

An array of tin-oxide sensors is used to continuously monitor different odour emissions in the environment. The paper presents some issues aiming at improving the portability and the user-friendliness of ... [more ▼]

An array of tin-oxide sensors is used to continuously monitor different odour emissions in the environment. The paper presents some issues aiming at improving the portability and the user-friendliness of the instrument as well as testing what kind of signal may be used to monitor the odour "intensity". Main results are the following. The test of various pre-processing data algorithms pointed out that the use of pure reference air could be avoided, as long as the sensors are allowed to periodically regenerate in the presence of ambient air. Sensor array in static contact with ambient air could be sufficient for the on-line monitoring, but the use of a controlled gas flow system to transfer the odour from the source is better to avoid the influence of air movement on the heated sensors. The control of the temperature and the humidity of the gas and the thermo-regulation of the sensor chamber don't seem essential, even for outdoor operation. When trying to build a regression model linking the odour intensity to the sensor signals, Partial Least Square (PLS) model gives better results with respect to Multi Linear Regression or Principal Component regression models. For an application around a landfill area, where sensor signals are compared to the personal feeling of the operator in the field, PLS gives a percentage of 71% correct intensity prediction. [less ▲]

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