The perception of ecosystem goods and services by local residents is studied in Brazzaville, around the periurban forest of Djoumouna. This study, which documents the ecosystem services provided to communities by this ecosystem facing anthropogenic degradation, evaluates the understanding and consideration of these functions, according to socioprofessional categories. Socioeconomic and ethnobotanical surveys conducted among the group of informants are supported by direct field observations and literature review. The data collected within a 2 km radius around the forest were subjected to descriptive and statistical analysis. The group of informants, including all socioprofessional strata, was organised into 4 age groups and involved 143 heads of household aged from 15 to over 45. The survey reveals 14 ecosystem services that fall into three categories. The provisioning services included food, wood energy, pharmacopoeia, and wood services. The regulatory functions cited are maintaining air quality, shade, erosion control, and windbreak. Recognized sociocultural services are the source of income, recreation, and ecotourism, source of inspiration, fishing, initiation sanctuary, and hunting. According to gender, men are more dependent on the forest than women, and those aged 15–25 and over 45 are the most active. The socioprofessional scale shows an unequal exploitation of the forest. The informants, at least for the majority, integrate the notions of the value of ecosystem services, provided by the Djoumouna periurban forest, into their daily lives. Finally, the study highlights the social and ecological value of periurban and urban forests in the daily lives of people and urban resilience.
Straddling the equator, Congo is located in Central Africa and covers an area of 342,000 km2. Savannah (35–40%) and forest (60–65%) are the main plant formations that divide up the territory [
The interest of Congolese forests on the triple economic, social, and ecological level is no longer to be justified. These ecosystems are a major lever for the development and the emergence of the Congolese economy [
Notwithstanding this main subdivision, which obscures small-area forest formations, notably urban and periurban forests, the direct and indirect ecological functions and roles played by the latter are not negligible in the maintenance of urban equilibrium. Urban and periurban forests are focal points for biodiversity conservation by providing alternative habitats for many plant and animal species [
Like all the woody formations in the world, the urban and periurban forests of Brazzaville provide a diverse range of goods and services to society. These products are subdivided into tangible (direct) and intangible (indirect) services. In addition to direct services, the most valued by local residents are wood products (firewood and service wood) and nonligneous forest products (NTFPs), including mushrooms, aromatic, medicinal, and food plants, and game; indirect services are exploited concomitantly. As direct goods and services are essentially related to the extraction, indirect ones are associated with regulation (water and mineral cycles, protection of watersheds and soils, carbon sequestration and climate change mitigation, protection and preservation of biodiversity, cultural and historical heritage, outdoor recreation, and leisure areas) and sociocultural ones.
However, in spite of the well-known benefits to local residents, the urban and periurban forests of Brazzaville are subject to increasingly intense anthropogenic pressures that have led to the disappearance of several of them [
This study, which documents the ecosystem services provided to communities by this ecosystem faced with anthropogenic degradation, assesses the understanding and consideration of these functions, according to socioprofessional categories. Thus, special emphasis should be placed on these periurban or even natural intraurban training courses, to which public managers pay almost no attention. In this respect, the data from the study, coupled with the bioecological and ethnobotanical findings, should usher in an era of better integration of urban and periurban forest management issues into Brazzaville’s urban development plans. Data on the perception of ecosystem services of the riparian’s of urban and periurban forests are likely to constitute an argument for the conservation of these formations [
The perception of local residents on the ecosystem goods and services derived from the Djoumouna periurban forest will be analyzed according to gender, age group, level of education, marital status, and socioprofessional activity.
The Djoumouna periurban forest (−04°22′ to −04°35′ S and 15°09′ to 15°15′ E) develops 24 km southwest of Brazzaville (Figure
Congolese forest presentation and location of the study area.
The soils evolving under the Djoumouna forest belong to two classes: highly desaturated ferrallitics whose sum of exchangeable bases (Ca, Mg, K, and Na) is very low in the B horizon (of the order of 1 meq/100 g) and a saturation rate of the absorbent complex lower than 20% [
At the phytogeographic scale, the periurban forest of Djoumouna belongs to the District of Cataractes, confined between the districts of Niari and Léfini. This mesophilic and tropophilic formation presents a flora based on species such as
The forest cover of Brazzaville, once lush and very extensive in the 1960s, included 5 natural woody formations that have only known varying fortunes as a result of anthropogenic activities [
The plant material at the centre of this study consists essentially of an inventory of woody plants (trees, shrubs, and lianas) and grasses in the Djoumouna periurban forest. The identification of the different taxa was done in situ for the most common ones. The others were identified in the national herbarium (IEC) by comparison of herbarium specimens and diagnoses of the flora of Central Africa, Gabon, and Cameroon. The ordination is based on the [
The survey, conducted from 6 to 25 September 2018, is based on an ethnobotanical and socioeconomic questionnaire. It integrates direct field observations and literature review. The target population consists of the residents of the Djoumouna periurban forest.
The data were collected in the supposed zone of influence of the Djoumouna forest, which extends over a radius of 2 km around the said formation (Figure
Location of the Djoumouna periurban forest and sampling plan.
Surveys involving 264 households helped to understand the perceptions of the people living in the Djoumouna forest on the ecosystem goods and services derived from the forest. The survey is based on a 47-question questionnaire, corresponding to three sections: identification of the respondent, authentication of the Djoumouna periurban forest assets, and investigation of the ecosystem services associated with the forest.
The questionnaire is based on multiple-choice questions relating to the identification of tangible (fruit, wood, and medicinal products) and intangible benefits (improvement of soil fertility, fight against erosion, cultural and social aspects, etc.) derived from this forest area. The choice of households surveyed was made at random, in the different zones of the dials, and the geographical coordinates of each of them were recorded. These parameters take into account the geographical position and distance of the riparian from the Djoumouna forest.
The survey data were manually tabulated before processing with Sphinx Plus 2 software, which allows results to be generated directly using either univariate or bivariate analysis techniques. The ecosystem services cited by respondents were classified into three categories based on the Millennium Ecosystem Assessment [
The data collected and classified were analyzed with some classic ethnobotanical indicators.
Citation frequency (CF) was calculated for each ecosystem service category:
For each category of ecosystem service, a use value (UV) defined in [
The informant consensus factor (ICF) defined in [
This indicator made it possible to calculate the level of fidelity (LF) of informants on the perception of ecosystem services associated with the Djoumouna forest. This indicator was calculated according to the formula described in [
Among 264 households surveyed, almost 3/4 (73%) agreed to complete the questionnaire, 19% of whom claimed not to be aware of the existence of the Djoumouna forest. Conversely, 27% refused to take part in the exercise. Taking gender into account, the group of informants is composed almost equally.
For 143 households surveyed, nearly 3/4 (72.8%) are located in equal proportions in zones 2 and 3. Zones 1 and 4, on the other hand, are home to 11.2% and 16.1% of households, respectively. According to georeferencing, the informants are classified according to three main axes: east (Dial 1), southwest (Dial 3), and northwest (Dial 4).
The subjects surveyed in each household are between 15 and over 45 years of age. The characterization of this population by age group reveals 4 age brackets with a difference of 10 years (Table
Synopsis of the informant group.
Age group | Individuals number | Contribution (%) |
---|---|---|
15–25 years | 40 | 28,0 |
25–35 years | 20 | 14,0 |
35–45 years | 24 | 16,8 |
45 years and over | 59 | 41,3 |
Total | 143 | 100 |
In relation to education, the majority of informants are at the secondary level (56%). The remaining portion of the educated is composed of primary (31.5%) and university (2.8%) levels. Finally, the unschooled fringe corresponds to 9.8%.
Marital status, all types combined, reveals that 54.6% of informants are married; 42% are single, and finally, 3.5% are divorced. The analysis of socioprofessional categories shows that the group of informants is composed of more than 3/4 workers and the remaining portion is made up of students (11.2%), civil servants (6.3%), unemployed (2.8%), and retired people (2.1%).
The riparian’s of the Djoumouna periurban forest identified fourteen ecosystem services in three categories (Table
Ethnobotanical value of the three categories of ecosystem services.
Categories | Ecosystem services | UV | LF | Ʃ | UVt | ICF | ƩLF | |
---|---|---|---|---|---|---|---|---|
Provisioning services | Human food | 42 | 0.29 | 7.6 | 93 | 0.65 | 0.96 | 16.9 |
Wood energy | 25 | 0.18 | 4.5 | |||||
Traditional pharmacopoeia | 14 | 0.10 | 2.5 | |||||
Service wood | 12 | 0.08 | 2.2 | |||||
Regulatory services | Maintaining air quality | 87 | 0.61 | 15.8 | 292 | 2.04 | 0.98 | 53 |
Shade | 84 | 0.59 | 15.3 | |||||
Erosion control | 71 | 0.49 | 12.9 | |||||
Windbreak role | 50 | 0.35 | 9.1 | |||||
Sociocultural services | Source of income | 48 | 0.34 | 8.7 | 166 | 1.16 | 0.96 | 30 |
Recreation and ecotourism | 44 | 0.31 | 8.0 | |||||
Source of inspiration | 35 | 0.24 | 6.4 | |||||
Fishing | 21 | 0.15 | 3.8 | |||||
Initiation sanctuary | 13 | 0.09 | 2.4 | |||||
Hunting | 5 | 0.03 | 0.9 | |||||
Total | 551 | 100 | 100 | 551 | 3.85 | 2.90 | 100 |
Almost half of the people living in the Djoumouna forest have recognized the food function provided by this ecosystem, and more than 1/4 have recognized the provision of wood energy (Figure
Ecosystem services provided by the Djoumouna forest: frequency of citation of sampling services (a); frequency of citation of regulatory services (b); frequency of citation of sociocultural services (c).
With the exception of the windbreak function, for which the number of citations by riparian in the Djoumouna forest is less than 25%; all others cover more than the remaining 3/4, overall (Figure
The sociocultural services provided by the Djoumouna forest are very diverse. Those that received more than 75% citations overall were income source, recreation and ecotourism, and finally, source of inspiration. The services related to the initiation sanctuary and hunting with the lowest citation rates appear marginal (Figure
The use value (UV) of ecosystem services as a whole ranges from 0.65 to 2.04. For functions, values range from 0.03 to 0.61. The total use value (UVt) is 3.85 (Table
Regulatory services are the most cited, with 53% of the residents of the Djoumouna periurban forest. Far behind and in order of importance are the sociocultural services, which have a citation rate of 30.12%, and finally, provisioning services with 16.87%. These data reveal that the consensus factor of informants for the different categories of ecosystem services ranges from 0.96 to 0.98 (Table
The most prominent ecosystem services are associated with the regulation service, including maintenance of air quality and shade. Considered individually, each service receives less than 25% of the fidelity level. The dispersion of the fidelity level means that the rate of each ecosystem service ranges from 0.9 to 15.8%. The range of values for the overall level of fidelity by service category is between 16.9 and 53% (Table
Men are the most active in the exploitation of ecosystem services in the provisioning services category. The focus is on food with 40% of the citations (Figure
Gender and perceptions of ecosystem services (%): frequency of citation of sampling services (a); frequency of citation of regulatory services (b); frequency of citation of sociocultural services (c).
Men are more alert to regulatory services than women. Both genders cite shading, maintenance of air quality, and erosion control (Figure
The operation of sociocultural services is in favor of men over women. Although the trend is the same within both genders, men's quotations are far above those of women. Recreation and ecotourism are favored over sources of inspiration and income, and hunting (Figure
The four selected provisioning services are mostly cited in the 15- to 25-year age group. This activism is noted for all ecosystem services in this category. It is also materialized in all age groups, but to a much lesser degree of citation (Figure
Perception of ecosystem services by age group (%): frequency of citation of sampling services (a); frequency of citation of regulatory services (b); frequency of citation of sociocultural services (c).
The majority of regulatory functions are recognized in the 15- to 25-year age group (Figure
Residents of all age groups favored the source of income, depending on the number of citations. Recreation and ecotourism, the source of inspiration, and fishing followed (Figure
The perception of ecosystem services by residents of the Djoumouna periurban forest is not correlated to the level of study. Whatever the service considered (provisioning services, regulating services, and sociocultural services), the Kruskal–Wallis statistical test does not reveal significant differences. All the observations of dominance made are purely relative. Indeed, the users would be empirically educated on the exploitation of the materials that guarantee their existence.
The level of education has almost no effect on the perception of the people living in the Djoumouna forest. Whatever the level, the number of citations is almost the same for all ecosystem services, except wood energy (Figure
Perception of ecosystem services by education level (%): frequency of citation of sampling services (a); frequency of citation of regulatory services (b); frequency of citation of sociocultural services (c).
Residents' perceptions of regulatory services are influenced by educational attainment. People at the university level (over 60%) favored maintaining air quality and the role of windbreaks. Those at the primary and secondary levels have more or less the same perception of the regulating services (Figure
Regardless of the level of education of local residents, recreation and ecotourism are, in that order, the most prized ecosystem services, both as a source of income and inspiration. Fishing, hunting, and cultural remain marginal (Figure
Regardless of the ecosystem service under consideration, the statistical data reveal that there are no significant differences in the different cases or even services.
Depending on marital status, single people are the most active group in the exploitation of ecosystem services. Except for the traditional pharmacopoeia where divorced people are dominant, single people stand out in terms of the number of citations. Fine analysis of the number of citations by group and ecosystem service shows that there is a very little divergence of use associated with status (Figure
Perception of ecosystem services by marital status (%): frequency of citation of sampling services (a); frequency of citation of regulatory services (b); frequency of citation of sociocultural services (c).
Regulation functions are popular with local residents regardless of status. Despite small variations in the number of citations, all recognize in this order shading, erosion control, and maintenance of air quality (Figure
In relatively little difference in the number of citations, the residents of the Djoumouna forest choose recreation and ecotourism as sources of inspiration and income (Figure
The majority of students cites the provisioning services selected. Preference is given to food, fuelwood, and service wood (Figure
Perception of ecosystem services by socioprofessional activity (%): frequency of citation of sampling services (a); frequency of citation of regulatory services (b); frequency of citation of sociocultural services (c).
Maintaining air quality and acting as a windbreak are the control functions emphasized by retirees and partly by unemployed residents (Figure
Unemployed local residents carry ecosystem services such as inspiration, recreation, and ecotourism (Figure
The data collected clearly show that the Djoumouna forest occupies a cardinal position in meeting the daily needs of the surrounding populations. In relation to the three ecosystem categories, the main services retained derive from harvesting, in no order of importance, are food, fuelwood, pharmacopoeia, and service wood [
The Djoumouna forest provides livelihoods for local residents by providing them with NTFPs of both plant and animal origin. As is most often the case, the food component constitutes the first service in the provisioning services category [
The people most dependent on the Djoumouna forest are men, especially those aged 15 and 25 and those over 45. The reasons for this are many and varied. The foundations are to be found in the functioning and dynamism, and even antagonism, of worldly and rural societies.
People's perception of the ecosystem services provided by the Djoumouna periurban forest decreases in proportion to their overall distance from the forest. However, the level of perception of regulation services, even in the very remote area, is not marginal. This observation authenticates that the regulatory functions provided by this ecosystem impact beyond the zone of influence of this study. The scope of the regulatory services provided by the Djoumouna periurban forest is not limited to the local scale but can be regional [
The consideration of remoteness as a distinguishing criterion is a major data showing that the highest use values are associated with the first zones. These values reflect the strong relationship of dependence of the populations of the nearby areas on the forest [
Based on the data collected on the direct and indirect benefits generated by the Djoumouna periurban forest, local residents derive an added value associated with intangible compensation. This value confers a high use value and a high fidelity level to the ecosystem services associated with this ecosystem [
Many people around the world, particularly in developing countries, still rely heavily on wood energy for cooking and heating [
The traditional pharmacopoeia, due to the prohibitive costs of modern medicine, is the primary recourse of more than one resident [
The informant consensus factor would be a discriminating element facilitating a synoptic view of the diversity of ecosystem services at the forest scale and an assessment of the relative importance of each of the categories represented [
The study highlights the ecosystem services provided by the Djoumouna periurban forest to the riparian populations. Their perception and the uses they make of it are the foundation of the work. The provisioning services, which are most valued by the riparian populations, provide both plant and animal nontimber forest products (NTFPs). In addition to the NTFPs that have a palpable value, the influence of this woody formation via the regulating services clearly exceeds the zonal situation.
In terms of the degree of exploitation of this ecosystem, the populations in the first areas (near and very near) are more dependent than those in the remote and very remote areas. Considering gender and age groups, men derive a greater share of benefits than women, whereas 15- and 25-year-olds and 45-year-old and over represent the fringe that frequents the forest the most. In social terms, the majority of the occupants are secondary school students, single people, and finally old retirees, especially divorced people with a university background.
Finally, the Djoumouna periurban forest is under strong anthropogenic pressure due to the abusive and uncontrolled use by local residents, which leads to a decrease in biodiversity and with it a decrease in the value of ecosystem services. Data on bioecological and ethnobotanical knowledge coupled with data on the perception of ecosystem services by local residents would be assets for developing a strategy for the conservation and sustainable management of biodiversity in the urban and periurban forests of Brazzaville. This would be a guarantee of a resilient city and the assurance of better living conditions for its citizens.
The dissertation and the database are available and can be consulted without restrictions, free of charge on request, at the IRF and at the Ecole Normale Supérieure of the Université Marien Ngouabi.
The authors declare that they have no conflicts of interest.