Fousseni Folega

Satellite monitoring of land-use and land-cover changes in northern Togo protected areas

Remote-sensing data for protected areas in northern Togo, obtained in three different years (2007, 2000, and 1987), were used to assess and map changes in land cover and land use for this drought prone zone. The normalized difference vegetation index (NDVI) was applied to the images to map changes in vegetation. An unsupervised classification, followed by classes recoding, filtering, identifications, area computing and post-classification process were applied to the composite of the three years of NDVI images. Maximum likelihood classification was applied to the 2007 image (ETM+2007) using a supervised classification process. Seven vegetation classes were defined from training data sets. The seven classes included the following biomes: riparian forest, dry forest, flooded vegetation, wooded savanna, fallows, parkland, and water. For these classes, the overall accuracy and the overall kappa statistic for the classified map were 72.5% and 0.67, respectively. Data analyses indicated a great change in land resources; especially between 1987 and 2000 probably due to the impact of democratization process social, economic, and political disorder from 1990. Wide-scale loss of vegetation occurred during this period. However, areas of vegetation clearing and regrowth were more visible between 2000 and 2007. The main source of confusion in the contingency matrix was due to heterogeneity within certain classes. It could also be due to spectral homogeneity among the classes. This research provides a baseline for future ecological landscape research and for the next management program in the area.

Disturbance and Population StructureofPlant Communities in theWildlife Reserveof Oti-Mandouri in Togo (West Africa)

Aims: As a contribution to the sustainable management of protected areas in Togo, this study aims to analyze the impact of anthropogenic activities on plant communities in the wildlife reserve of Oti -Mandouri (North-Togo). Study Design:The study area is located in the Sudanian zone, in northeast Togo. Place and Duration of Study:The field work was carried out during April and June 2009, whilst processing data was done at Lab From July to October 2009. Methodology: Total height and stem diameter at breast height (dbh) greater than 10 cm of all trees species were measured in 126 plots. In each plot, ecological parameters were recorded and the seedling and suckers (dbh<10cm) of species were counted. Results:116 woody species with dbh greater than 10 cm belonging to 33 families and 84 Original ResearchArticle

Quick numerical assessment of plant communities and land use change of Oti prefecture protected areas (North Togo)

In this paper, the analysis of Land sat images and plant ecological assessment were used to determine the land use change, plant diversity and the main plant community patterns in most environmentally disturbed areas of northern Togo. Floristic data in the survey areas were collected using transect and sampling methods which were both based on Braun Blanquet phytosociology concept. Several numerical processes were then retained to analyze the floristic data such as Detrended Correspondence Analysis (DCA), Hierarchical Clustering and Indicator Value (INDIVAL). The first two analyses were to define the plant groupings while the third was to name the plant communities found. The logical technique of RGB-NDVI suggested by Sader and Winne as an essential tool for land use assessment was applied to remote sensed data covering three time periods (1987, 2000 and 2007). The Normalized Difference Vegetation Index (NDVI) was then applied to both images after atmospheric correction before stacking them to obtain a RGB_NDVI composite image. Finally an unsupervised classification followed by post-classification process was applied to the RGB_NDVI image. All the results from these analyses show that seven plant groupings can be found in this area which mostly represents the physiognomy of shrubby savanna. The most frequent, abundant and typical plant species to Sudanian area are Terminalia laxiflora, Crotalaria graminicola, Vitellaria paradoxa. Great mutations in land use change are well perceptible after analysis. In overall the harvest of plant resources was higher between 1987 and 2000 while the regrowth of biomass was limited and unequal. The areas characterized with biomass clean and or regrowth is well represented in term of superficies, which denote the level of anthropogenous disturbance factors prevailing in this zone. However, there are certain zones where changes have not happened yet such as a few dimensions in riparian forests, though according to the field observations these riparian forests and their neighboring wooded vegetation are very disturbed. The rivers, pounds, barren lands and the scattered villages are also considered as no change areas.

Status of Hagenia forest in the Parc National des Volcans, Rwanda: A review of historical records

Hagenia-shaped habitat is an important element in conservation of world’s only population of mountain gorillas surviving in the wild. In fact, in the Parc National des Volcans (henceforth PNV), gorillas spend most of their life time in the nutritious herbaceous habitats near or within the Hagenia-Hypericum zone. Unfortunately, populations of Hagenia abyssinica in this park have been reported to be ageing. Using information drawn from the statistical analysis of records in herbaria and the cross−examination of the literature, the status of Hagenia forest in PNV is discussed. The results show that H. abyssinica in PNV has an unusual pattern of population structure and distribution, seemingly since many decades. No record of H. abyssinica was collected from PNV, but patterns of collections of H. abyssinica are globally similar to those of a set of five control tree species, such that this absence of records from this park cannot be considered as due to collector or collection site-bound bias. The paper ends by giving insight on possible implications for conservation of the park’s wildlife, chiefly the gorillas. Key words: Tree regeneration, herbarium records, afromontane forest.

Changes in Land Cover Categories within Oti-Kéran-Mandouri (OKM) Complex in Togo (West Africa) between 1987 and 2013

Oti-Keran-Mandouri (OKM) is a complex of protected areas with national and international ecological importance. It is located in the flood plain of the Oti River in Togo. Unfortunately, this area is under anthropogenic pressure. In order to enhance biodiversity conservation, this study aims to assess the spatial changes in land cover within OKM. Landsat images from different missions spanning the time steps 1987, 2000 and 2013 were used to produce land cover maps involving six classes. The classification was based on the maximum likelihood algorithm and the change analyses were performed using Land Change Modeler software integrated in Idrisi GIS and Image Processing system. From 1987 to 2013, wetlands, forests and savannahs diminished while cropland and settlements expanded. Considering the overall area of OKM, wetlands decreased from 43.05 % in 1987 to 31.71 % in 2013. Meanwhile, croplands increased from 0.91 % in 1987 to 34.81 % in 2013. Considering their earlier areas in 1987, forests, savannahs and wetlands have experienced an average annual loss of 5.74 %, 3.94 % and 2.02 %, respectively, while croplands increased at an average annual rate of 285.39 %. The main drivers of these changes appear to be the inadequacy of the management system and increasing anthropogenic pressures. These are intensified by climate change since adaptive strategies, such as recessional agriculture, play an important role in land cover change. The ongoing process of rehabilitation should be strengthened to enable this protected area to play its roles as Ramsar site, biosphere reserve and priority corridor for the migration of the West African savannah elephant. Data from this study could be used to guide conservation planning, further landscape pattern assessment and land cover modelling in the framework of climate change.

Long term evaluation of green vegetation cover dynamic in the Atacora Mountain chain (Togo) and its relation to carbon sequestration in West Africa

The research was done in the Atacora Mountain chain in Togo which tended to assess the change of vegetation cover during a 24-year period. It also aims to evaluate the dynamic of the net primary productivity (NPP) of the living plants over the same period. The Landsat imagery covering three different periods (1987, 2000, and 2011) was pre-processed to correct atmospheric and radiometric parameters as well as gapfilling the 2011 SCL-off images. Then, the vegetation indices such as NDVI (normalized difference vegetation index), SR (simple ratio vegetation index), SAVI (soil-adjusted vegetation index), and CASA (carnegie- ames- stanford approach)model for NPP were applied on these images after masking the study area. The results showed a quiet decrease in the vegetation cover. The vegetation loss was more significant from 2000 to 2011 than from 1987 to 2000, and anthropogenic activities can be deemed as the main cause of the vegetation loss. The biomass assessment by NPP computation also showed a decrease over the time. Similar to the change of the vegetation cover, the ecosystem net productivity was very low in 2011 compared to 2000 and 1987. It seems that the general health condition of the vegetation, including its potentiality in carbon sinking, was negatively affected in this area, which has already been under threatened. A perpetual monitoring of these ecosystems by means of efficient techniques could enhance the sustainable management tools of in the framework of reducing emissions from deforestation and forest degradation (REDD).

Carbon Stocks of Coarse Woody Debris in Central African Tropical Forests

Coarse W oody D ebris (CWD; defined here as fallen and standing dead trees and tree branches) is a critical-structural and functional component of forest ecosystems that typically comprises a large proportion of total aboveground carbon storage. Coarse woody debris estimation for the tropics is uncommon, and little is known about how carbon storage in CWD will respond to climate change. Given the predominant role that tropical forests play in global carbon cycling, this information gap compromises efforts to forecast climate change impacts on terrestrial carbon balance. In this study, we aimed to identify the variation in C oarse W oody D ebris (CWD) stocks between forest types (Old-growth and selective logging forests) and among the plots in Ipendja mixed lowland terra firme tropical rainforest (central Africa), and we examined the consequence for CWD carbon stocks estimation. The study area is located at Ipendja forest management unit (UFA), close to Dongou district (Likouala Department), in Northern Republic of Congo. Data collection were done with eight rectangular plots, each 25 x 200 m (0.5 ha). The method of line intercepts sampling has been used in each studied site. A total number of 135 CWD samples of diameter ³ 10 cm in the studied plots have been recorded. It was obvious that stock of coarse woody debris in Mokelimwaekili site (mean: 19.96 Mg ha -1 ; sum: 79.84 Mg ha -1 ) were higher than those of Sombo site (mean: 8.9 Mg ha -1 ; sum: 35 Mg ha -1 ). There was a significance difference in Ipendja evergreen forest about CWD stocks across two forest types and plots. This finding suggests that values vary among forest types and that separate reference values should be adopted for estimates of undisturbed forest carbon stocks in the different ecosystems in Congo basin. Different reference values represent the variability of CWD among forest types and contribute to reducing uncertainties in current estimates of carbon stock in central African forest ecosystems.