{'fraction_non_alphanumeric': 0.040501880006539155, 'fraction_numerical': 0.02448095471636423, 'mean_word_length': 4.95352798053528, 'pattern_counts': {'":': 0, '<': 11, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Exploitation and Sustainable Management of the Biodiversity of the Ngaoundéré

A study was conducted on the exploitation of natural resources and the sustainable management of the vegetation of the Ngaoundéré cliff. Structured and semi-structured interviews were conducted with 350 people, 50 per village. The data obtained were supplemented by direct field observations. Data analysis using Excel, STATGRAPHICS Plus 5.0 and XLSTAT showed that farmers (88.93%), breeders (80.07%), craftsmen (49.29%), hunters (28.93%) are the main operators of the resources of the cliff. The products exploited are involved in food (55.28%), medicine (30.51%), crafts (53.34%), and trade (43.54%). The most commonly used species in the cliff are Borassus aethiopum (100%) and Mangifera indica (100%) in the diet, Isoberlinia doka (68.17%) as firewood, Khaya senegalensis (63.50%) in the medicine, Piliostigma thonningii (100%) for artisanal use and edible NTFP (40, 63%) in the trade. Faced with this exploitation of the biodiversity of the vegetation of the cliff, a forest management plan has been developed in a spirit of community management based on the participatory approach which invites all actors and social partners to take part in the decision making based on consensus between the conservative trend and the local population.


INTRODUCTION
Forests in Central Africa and other tropical forests represent a large reservoir of biological diversity. They are important sources of income for the countries of the subregion in both the formal and informal sectors [1]. In most Congo Basin countries, logging remains the main provider of private wage employment, particularly in remote rural areas. In this sub-region of Africa, millions of people depend on forests for the daily satisfaction of their needs: timber, timber, energy, arable land, non-timber forest products, and so on [2,3]. Most of the earth's landscapes are currently transformed by human activities to meet the socio-economic needs of the population [4]. These results in human pressure resulting in deforestation that has reached the rate of 673,000 ha per year, an annual shrinkage rate of 0.28% in the period 2000-2005 [3]. The fact that some countries continue to increase the amount of forest area devoted to production without sustainable management insurance is a threat in prospect [5]. Likewise, population growth and its corollary, the need for arable land and pastures, point a growing trend in deforestation. Because of their major importance for global biodiversity and the global carbon cycle [6,7], tropical forest conservation has become a global issue. The issue of conservation of biodiversity and preservation of the environment has triggered a revolution in tropical countries. Many organizations promote NTFPs in Central Africa to improve forest management and contribute to raising living standards in rural areas [8]. However, the impact of the forest sector on national economies remains poorly documented to provide the deserved visibility and sustainable management of these resources. This partly explains the growing interest that economic policy guidelines give to this sector, based on a perception that the contribution of forest resources to economic growth remains marginal [9].Cameroon's forests are rich in NTFPs. However, the sector suffers from defects that may be detrimental in the long term on the sustainable management of NTFPs, namely lack of knowledge of the resource, lack of standards of rational exploitation, lack of quality products and unclear and inefficient regulations [1]. Many difficulties still hinder the ecologically and economically profitable exploitation of special products for the State and individuals. Indeed, a major obstacle to the sustainable management of tropical forests is the scarcity of knowledge about species, stand structure, history of ecosystems and their relationship to anthropogenic and climatic disturbances [10,11]. The potential of these products, even as an indication, is not known. In the absence of inventory data, the sustainability of the exploitation of these resources conducted with fifty (50) people per village. The questionnaires included identification variables of the respondents (name, forenames, age, sex, level of education, village) and questions concerning the activities carried out inside and on the periphery of the cliff, the perception that populations have forest space and their participation in the management of this area. Complementary surveys of the use of forest products by women, on the practices of transhumant pastoralists on the activity of professional loggers were carried out. Specific surveys were conducted among user groups that do not have a great impact on the plant resource (potters, weavers).

STATISTICAL ANALYSIS OF THE DATA
Analysis of variance using the XLSTAT and STATGRAPHICS Plus 5.0 software was used to verify differences in number and surface treatments. Excel was used for averaging and histogram representation. In the presence of significant variance analyzes, mean comparisons were made using Fisher's test.

RESULTS
Actors exploiting the biodiversity of the Ngaoundéré cliff Table 1 presents the different categories of actors exploiting the forest formation of the Ngaoundéré cliff. This table shows that six actors intervene in the exploitation of resources. Farmers (88.93%) are the first actors of the vegetation. They practice slashand-burn agriculture in all villages. Breeders (80.07%), the second largest group, graze their animals in the forest landscapes of the cliff. They practice bush fires as a grazing rejuvenation system. Craftsmen (49.29%) use resources for building habitats, dyes and other handicrafts. The other groups consisting of hunters (28.93%), blacksmiths (9.64%) and fishermen (6.07%) are less present in the exploitation of forest resources of the cliff. In addition, some actors, poorly represented groups are absent in some villages. These are the blacksmiths absent at Taa-toyo and Gob-gabdo and the fishermen absent at Tchabbal. In each village, the same individual exercises more than two activities at a time. The analysis of the variances reveals a significant difference between the actors (0.000<0.001).  Figure 2 shows the distribution of forest resource operators in the study sites by sex. The resource operators are mainly men (65.36%), ie 57.50%, 75%, 65%, 62.50%, 85% and 70% in the villages Taa-tooyo, Gob-gabdo, Wack, Ndom Karna and Tchabbal respectively. The village Gop makes an exception with more than half (55% of women). This is due to the multiple activities that men perform in relation to forest landscapes such as fishing, hunting, crafts, firewood trade and construction, and traditional pharmacopoeia, which are exclusive to the male sex. The high proportion of men may also be justified by the fact that these activities require a lot of energy and because in the traditional context, women are required to stay in households to perform certain domestic tasks. In addition, the Student's t-test reveals that there is a highly significant difference between the sexes (0.035<0.05).

Fig-2: Resource distribution of operators by sex
The bands with the same letter indicate that the corresponding values are not statistically different at the 5% threshold.

Distribution of forest resource operators by age
The distribution of the operators of vegetation exploitation according to their age is illustrated in Figure 3. It appears that the individuals having an age between 25 and 45 years (61.79%) are the most represented. The extreme values of this age group are observed in Karna (40%) and Taa-toyo (80%) villages. Individuals aged 45 or older (15.36%) are relatively less numerous on the farm. We note that in the villages Taa-tooyo and Gob-gabdo, this representativeness is zero. The youngest, less than 25 years of age, use forest resources moderately compared to others. However, at Wack and Ndom, their proportion is very small. Individuals under the age of 25 are not very interested in farming because they are too young and do not have too much responsibility. Among the operators, the individuals between 25 and 45 years old, mainly young people, are the most numerous because they have the energy necessary to carry out hard and difficult work. The analysis of variances shows that there is a very highly significant difference between age groups (0.000<0.001).

Fig-3: Distribution of farmers by age group
The bands with the same letter indicate that the corresponding values are not statistically different within 5%.

Distribution of forest resource operators by Ethnicity
The forest resource operators are grouped into five ethnic groups unequally distributed in the different villages: Baya, Dii, Fulani, Mboum, Ngambaye and Toupouri ( Figure 4). The majority actors are Dii represented in all the villages, followed by Baya, Fulani and Mboum, which are found in at least three villages. The Baya are present in the villages Gob-gabdo (17.50%), Gop (5%) and Tchabbal (22.50%). The Fulani are found in villages Wack (22.50%), Gop (15%), Ndom (7.50%), Karna (20%) and Tchabbal (17.50%). The Mboum are present in Wack (12.5%), Karna (5%) and Tchabbal (10%). The Ngambaye and Toupouri, the least represented, settled in only two villages. This strong dominance of the Dii shows that they are the first occupants of Wack and Tchabbal. The other ethnic groups come from other localities where they found fertile lands for agropastoral activities. These are Toupouri who came from the Far North and settled in Taa-toyo village and others in Tchabbal for agricultural activities. The Fulani settled in these villages for their trade and breeding. The analysis of variances reveals a significant difference between ethnic groups (0.016<0.05).

Fig-4: Distribution of farmers by ethnicity
The bands with the same letter indicate that the corresponding values are not statistically different within 5%. Table 2 lists the woody species, sources of NTFPs used in human nutrition. In total, seventeen plant species provide the majority of NTFPs for consumption. Mangifera indica (100%) and Borassus aethiopum (100%) are the species most appreciated by local populations. They are followed by Tamarindus indica (93.57%) and Vernonia amygdalina (86.00%). Both species are appreciated by the entire population of Gop. Strychnos spinosa, the least exploited species as a food source, is appreciated by only 20% of the Taa-toyo population and 2.5% of the Karna population. Mangifera indica, an exotic species, is introduced into the cliff only by humans and the animals that consume it. On average, the village of Taa-tooyo (62.65%) uses more food NTFPs than the villages Gob-gabdo (58.62%), Karna (57.21%), Gop (56.03%), Wack (53.50%), Tchabbal (51.32%) and Ndom (49.76%). Statistical analysis reveals a significant difference between species and between villages (p<5%). Numbers assigned the same letter of the same row or column is not statistically different at the 5% threshold. Table 3 summarizes the species used by local populations in traditional medicine. Fifteen species of listed medicinal plants testify to the importance given to the pharmacopoeia by the populations. Khaya senegalensis is the most exploited species with 68.93% followed by Vitellaria paradoxa (56.43%). Ficus platyphylla is poorly used for health care (5.71%). The high exploitation rate of Khaya senegalensis is due to its various healing properties. The results of the surveys revealed the many medicinal uses of this species by local populations. Indeed, the populations treat the toothache based on Khaya senegalensis. Some people use Khaya senegalensis to treat diarrhea. Others use it for the regulation of abundant and good quality breast milk production, burns, chronic weight loss and dysentery. The population of Taa-toyo (39.67%) ranks first in the use of medicinal species. Then come the villages Wack (32.17%), Karna (31.50%) and Gob-gabdo (28%). Operators in Ndom (24.07%), Tchabbal (21.67%) and Gop (18.67%) villages use very little. Variance analysis reveals a significant difference between species and between villages (p<5%). Numbers assigned the same letter of the same row or column is not statistically different at the 5% threshold.

Plant operation as firewood
In total, twenty-four woody plant species are commonly used by local populations for firewood ( Table 4). The most soughtafter species are Isoberlinia doka (66.07%), Anogeissus leiocarpus (64.64%), Daniellia oliveri (57.14%). However, Bombax costatum (3.21%), Grewia flavescens (5%), Syzygium guineense var. macrocarpum (6.07%) are less used as firewood. Some species are used only in two villages. This is for example Syzyguim guineense var. macrocarpum used only by 40% of the population of Wack and 2.50% of the population of Ndom and Bombax costatum exploited in the villages Gob-gabdo (7.50%) and Wack (15%). Others such as Sarcocephalus latifolius are exploited in four villages. This variation is confirmed by a significant difference in the 5% threshold between species and between villages (P<5%). The numbers assigned to the same letter of the same row or column is not statistically different at the 5% threshold.

Importance for crafts
Nine species are used as building materials, basket-making, hats, tablecloths and furniture (Table 5). Piliostigma thonningii (85.36%) and Sterculia setigera (21.79%) are used for ropes. Isoberlinia doka (63.21%), Pterocarpus lucens (68.93%), Terminalia laxiflora (70.36%), Terminalia glaucescens (49.21%), Daniellia oliveri (37.14%), Afzelia africana (18.21%) Serve as poles for the construction of houses, wood for the manufacture of Tam-tams as well as mortars. Analysis of variances shows a significant difference between the species used in crafts and between villages in the exploitation of resources (0.000<0.001). The numbers assigned to the same letter of the same row or column is not statistically different at the 5% threshold.

NWFPs of animal and fungal origin
NWFPs of animal and fungal origin have been identified (Table 6). So, thirteen types were identified. Termites (86.79%) Are the most sought after by the populations in all the villages? They are consumed by all the surveyed populations of Taa-toyo and Tchabbal. Mushrooms (84.29%) are the second most exploited NWFP. They enter into the preparation of the sauce and are marketed outside and inside the Adamawa region. In the villages Taa-toyo and Gob-gabdo, all populations are mycophagous. The preference of these two NWFPs is simply due to their easy accessibility. The low use of animals in this case the monkeys (Cercocebus albigena), the porcupine's pigs (Hystrix christata), the hares (Lepus capensis), the warthogs (Potamochoerus porkus), the pangolins (Manis giganthea) is since they are protected against human threats. The villages have the same rate of exploitation of NWFPs of animal and fungal origin. The population of Taa-Toyo (48.54%) Uses more resources than Gob-gabdo (46.81%), Tchabbal (45.88%), Ndom (45.88%), Karna (40%), Wack (37.22%) and Gop (31.88%). Analysis of variances showed a significant difference between species and villages (0.000<0.001). The numbers assigned to the same letter of the same row or column are not statistically different at the 5% threshold.

Market values of the forest resources of the cliff of Ngaoundéré
The exploitation of forest products is intended not only for consumption but also for marketing. Table 7 lists the types of trade-involved forest products. It shows that 39.44% of the population is occupied by this activity. In addition, fuelwood is the first most marketed product with a prevalence rate of 59.64%. It is followed by edible forest products and timbers with marketing rates of 40.81% and 17.86% respectively. The populations of Taa-Tooyo and Gob-gabdo are most interested in the commercialization of these resources. The abundant use of firewood as a source of energy is conditioned by its price and availability [27]. Forest products are sold in several forms and prices vary depending on the type of product (Table 8). Bush meat, for example, can only reach urban consumers in dried or smoked form. As for the prices, they range from 500 FCFA for the piece or package from 0.5 kg to 10000 FCFA for the whole game of 10 kg. Fuelwood is sold in the form of charcoal or bundles of firewood. The resources of the Ngaoundéré cliff play an important role in the economy of the riparian populations. These incomes make it possible to partially fill the budget deficit of the sector's direct players. But the rate of marketing of these resources remains low. Most NWFPs in the forest formation of the cliff are used according to a livelihood strategy by the populations; Above all for their own consumption and possibly for an income that remains marginal. The numbers assigned from the different letter of the same row or column is statistically different at the 5% threshold.

Perception of cliff degradation and associated phenomena
Most riparian populations perceive the decrease in the vegetation cover of the Ngaoundéré cliff. Only 5.72% of respondents observed vegetation stability in the last twenty years ( Figure 5). The phenomena associated with this degradation include the decrease in rainfall (95.42%), the decline in agricultural productivity (93.46%), the increase in drought (87.71%), the increase in temperature (86.85%), the decrease in the plant productivity (82.85%), water drainage (45.71%), the regularity of floods (43.74%) ( Table 9). The statistical analysis reveals a significant difference between the various consequences of the degradation of vegetation cover perceived by local populations (0.03˂0.05). The numbers assigned to the same letter of the same row or column is not statistically different at the 5% threshold.

Traditional vegetation management methods
The exploitation of plant resources is an important part of the local community. The protection strategies developed by the populations are less to care about the environment than to make the most of this potential. Table 10 presents traditional methods for the development of cliff vegetation by riparian populations. It is clear from this table that the populations contribute to the conservation of the vegetation. Customary practices (51.07%) are the most important means of conservation by local people. The conservation of village forest relics known as sacred wood for cultural or religious purposes is practised at least by half of the population in all villages except for Gop and Tchabbal, where most populations do not give importance to customary practices. Traditional regulation through the organisation of hunting and fishing (50.36%) at a given time is the second means of preserving biodiversity to limit and regulate the exploitation of animal resources at any time. In addition to these two protective measures, the introduction of species through the creation of fruit tree plantations (24.64%) to alleviate a shortfall at economic, sociocultural and scientific level, case gardens (30.71%), the creation of agroforestry systems (22.86%) For the maintenance of soil fertility or for the supply of forest products to humans. Unlike the populations of other villages, those of Taa-Tooyo (21%) and Gop (26.50%) contribute less to the conservation and preservation of biodiversity. Analysis of variances reveals a significant difference between the methods undertaken by the local population and between sites (0.000<0.001). The numbers assigned to the same letter of the same row or column is not statistically different at the 5% threshold. Table 11 presents the measures for co-management of cliff vegetation by riparian populations. The ban on the production of coal (100%), the penalties for illegal holdings (100%), the ban on the levying of green timber (68.21%), the raising of the population on the practice of bush fires (49.36%) are the management methods applied by local populations to limit the anarchic exploitation of natural resources to ensure their sustainability. The statistical analysis detected a significant difference between the different methods of co-management and between sites (0.000<0.001). The numbers assigned to the same letter of the same row or column is not statistically different at the 5% threshold.

DISCUSSION
The vegetation of the cliff of Ngaoundéré is highly exploited for agriculture, breeding and forest products that are not woody and woody. The main actors of this exploitation are the men. Similar results were obtained in the peri-urban savannas of Ngaoundéré by Tchobsala [28] which showed that it is the men who are most involved in the exploitation of the woods. Among the men who exploit the vegetation of the cliff, the young are the most numerous because they still have energy to carry out hard and arduous work. Similar results were found by MINEF [29] in the Mayo-Louti, which showed that young people are the most active in the exploitation of plant resources. In addition to the natives of the seven villages in the study area, transhumane shepherds and poachers are not the least in the exploitation of the cliff vegetation.Many people exploit the vegetation of the cliff of Ngaoundéré to obtain non-wood forest products for food, service, trade, health, handicrafts, firewood etc. to reduce the unemployment rate in the seven villages. In general, operators use these natural resources to treat themselves to the native, as this plant formation is a natural, imperishable and inexhaustible pharmacy, at a lower cost to humans [22]. Further work was obtained by Tchobsala [28] in the peri-urban savannahs of Ngaoundéré, which showed that several species such as Annona senegalensis, Khaya senegalensis, Securidaca longepedunculata, Fagara senegalensis etc. are used in traditional Pharmacopoeia. Dongock and et al. [2] have shown that species such as Ximenia americana and Tamarindus indica are highly sought after as firewood and the to produce coal in the Sudano-sahelian zone of Chad. But the rate of marketing of these resources remains low. Most NWFPs in the cliff vegetation are used according to a population subsistence strategy; above all for their own consumption and possibly for an income that remains marginal. According to FAO [8], these products are essential for the livelihood of populations dependent on forest landscapes and reduce poverty. The very significant consumption of fuelwood by the population is an indicator of the depletion of trees in the cliff. In the same vein, Mapongmetsem and Akagou [30] reported that the situation of fuelwood is already alarming in the Adamawa in the years 97. Some families use mushrooms as food and traditional sources. Similar results were obtained by Toirambe [31] in the Democratic Republic of the Congo. He showed that in all the households visited during his study, more than half of the population harvests the mushrooms that are part of their food tradition. It is according to Ramakrahnan [32] that, in the Sudano-Guinean savannas, the income derived from the exploitation of NWFPs such as plant products and animals, although still poorly estimated, would be about twenty billion a year. The income allows to partially fill the budget deficit of the direct actors of the sector. To ensure the sustainability of these resources to satisfy future generations thus remedy the problem of overexploitation of the natural resources of the vegetation of the cliff of Ngaoundéré and its environs, a development plan including the local population and the Cameroonian government in charge of forests and wildlife was developed. Participatory co-management measures are being taken by the local populations and the ministries responsible for forests for sustainable management and conservation of biodiversity. These results corroborate those of Ntoupka [33] in the Sudano-Sahelian zone at Laf, which showed that populations are far from passive actors in the face of degradation through reforestation and planting of fruit trees.

CONCLUSION
The study on the exploitation of natural resources on the biodiversity of the Ngaoundéré cliff shows that farmers, breeders, craftsmen, hunters are the main actors in the exploitation of natural resources. The products are used in food, traditional medicine, crafts, and trade. Co-management is an effective measure used to safeguard the vegetation of the anthropization.