Sociocultural and Ecological Dynamics of Green Spaces in Brazzaville (Congo)

-e study was conducted in Brazzaville, and data collection covers the period fromMay to June 2017.-emethodology is based on literature review and floristic and equipment inventory. Nine green spaces spread over two out of nine townships in the capital city. Four are located in Bacongo and five in Poto-Poto. According to the classification standards, 5 squares and 4 gardens were studied. Except for one square, all the others, including the gardens, are planted with trees. -e equipment inventory lists 183 benches, including 63.83% permanently and/or partially in the sun, 4 playgrounds, no games for children, and 3 cultural monuments. -e flora and health of the trees stands shows 186 trees and 279 shrubs, all corresponding to 26 species. An examination of the health status reveals that 57% of trees show anthropogenic injuries. Floral analysis shows that exotic plants (76.92%) predominate over local plants (23.07%). -e average basal area of trees in all green spaces is 1.95m·ha . -e diametric structure is erratic within all green spaces, with a dominance of large diameter subjects. -is leads to poor natural regeneration of woody plants. -e green spaces in Brazzaville, which are very unevenly distributed within the urban fabric, do not meet the international standards disseminated by the World Health Organization (WHO) and do not fully play their biodiversity conservation and recreational and ecological functions. History of green spaces in Brazzaville states that no creation was born after independence. -e existing land has been reduced in size, and the new land has been used for other purposes.


Introduction
e term green space is not new, and Choay and Merlin [1] report that this term first appeared in 1925, coined by Forestier, park curator, Paris garden. It spread in the 1950s, when it designated open and unpaved areas [2]. e green space designates, commonly in an urban or suburban area, an area with vegetation, ranging from a simple square to a large park through road plantations. Green spaces embellish the environment of cities according to several modes such as social as a place of rest and walk within everyone's reach; biological for the production of oxygen by trees and their contribution to the mitigation of several nuisances related to climate, and human health and economic benefits [3][4][5][6]. It should be noted that these designations meet criteria inherent to the area covered [7].
Areas of natural urban and periurban forests around the world are shrinking dramatically, and with them biodiversity is eroding [8]. Green spaces would be one of the ideal solutions to this phenomenon [9,10]. In addition to biodiversity conservation, they would, as in other countries, be appropriate environments for environmental education, introducing the scientific popularization of ecological phenomena in which the tree interacts closely with its natural environment [11,12]. Although they are vectors of pollution, the services rendered by trees through direct and indirect benefits are no longer to be demonstrated. e aspects cited as examples are air purification, dust retention, chemical air cleaners, noise pollution, soil protection, thermoregulation, climate regulation, and bio-geochemical cycle [4,9,[13][14][15][16]. In the role of air pollution control and thermoregulator, Vergriete and Labrecque [17] show that plants and/or frequenting green spaces reduce the risks of certain ailments such as stress, respiratory infections, and migraines [18][19][20][21][22][23].
With the promulgation of the World Health Organization (WHO) Healthy Cities Programme [24,25], the environment is considered a determining factor for the comfort, well being, and health of all. More and more, we are becoming aware of the fact that the environment in which the population lives is preponderant for its physical and moral balance. Among the means of improving this framework, green space is a very important component [26]. Indeed, green space is greatly valued for its contribution to the quality of life in the urban environment. Efforts to improve urban centres in developed countries have almost all been accompanied by attention to the creation, development, and use of green space [27].
In Africa, and more particularly in Congo, the place of the green space has never been the subject of real attention. Green spaces are unevenly distributed in the urban area, and postcolonial neighbourhoods are generally the most neglected [28]. ere is also very little natural regeneration of these trees, most of which are senescent. Most species are ornamental and exotic [29]. Today, these nonfunctional and constantly degrading green spaces do not fulfil their primary vocation (ecological, biodiversity conservation, social, and recreational) and play only a derisory role [12].
More than half a century since the Congo gained independence, the urban plan of the city of Brazzaville has remained static on the development offer of green spaces and on the quality of life. e colonial period was marked by the creation of green spaces for an attractive, green, and relaxing urban living environment. is embellishment is based on the exploitation of the virtues of native and nonnative tree species [28,29].
In the city of Brazzaville, the areas and facilities devoted to recreational green spaces are clearly insufficient and inadequate or even unsuitable for some. Since the 1960s, there has been a growing public interest in recreation and leisure. Rest after a working day and during holidays has become a necessity. us, offering the citizen an adequate framework for relaxation should be a permanent feature in any urban development plan. e involvement of green spaces in the well being of the urban community of Brazzaville and the mitigation of the harmful effects of global climate change are the foundations of this study. e main objective of this study is to review the management of green spaces in Congo and particularly in Brazzaville, given that green spaces play an important recognized role in the conservation of biodiversity in general and plant diversity in particular and in the provision of goods and services to the population.

Materials and Method
2.1. Study Environment. Created in 1884, the city of Brazzaville, the capital of the Republic of Congo, is located on the banks of the Congo River (Figure 1), in the south of the country between 04°04′S and 15°02′E [30] covering an area of 326.40 km 2 with an estimated population of 1,373,382 [31,32]. Administratively, the Brazzaville autonomous department has 9 townships. e climate in Brazzaville is humid tropical, with a rainy season from October to May, a dry season from June to September (Figure 2(a)), an average annual temperature of about 25°C, and an average annual rainfall of 1,400 mm [33,34]. March, April, and November are the rainiest months and June, July, August, and September are the driest (Figure 2(a)). Relative humidity is particularly high, always above 70% (Figure 2(b)), with an absolute minimum in August and September and a relative minimum in February and March. e minimum varies between 50 and 60%, the maximum vary from 88 to 94%. Evaporation (Figure 2(b)) shows a relative maximum from February to March and an absolute maximum in August and September [35]. e average annual sunstroke varies between 1,700 and 2,000 hours. e insolation curve has two maxima from March to May and in November and minima from June to August (Figure 2(c)).

Study Material.
e study material consists mainly of trees, shrubs, grasses, rest facilities, leisure facilities, and cultural monuments. e trees and shrubs were counted and identified, while the herbs were simply identified. e measurement of woody trees including the diameter at breast height (DBH) ≥10 cm at 1.30 m height is systematically carried out. It is noted concomitantly that the individuals present signs of anthropic aggression (removing the bark of the trees). In addition, all cultural facilities and monuments have been identified. Finally, the area of each green space is evaluated.

Classification and Nomenclature of Green Spaces.
In urban or periurban areas, green spaces are vegetated areas whose typology is based on precise criteria based on the area covered [7,[36][37][38].
us, we distinguish the following different types of spaces: (i) Square: area less than 1 ha (ii) Proximity garden: area between 1 and 4 ha (iii) Urban park: area greater than 5 ha (iv) Periurban park: area greater than 100 ha Parks often offer water supply points, afforestation beds, and ornamental trees, but also created spaces such as lawns.
eir location shows a recreational, sports, or relaxation vocation, with the presence of playgrounds, sports equipment, and benches. However, a public garden and a square are small spaces. e public garden is designed as a place to relax, and a square is seen as a meeting place. According to WHO, at least 10 m 2 of green space in urban centres and 25 m 2 in periurban areas are recommended per inhabitant [38,39].

Study Method.
e study method is based on literature data and inventory data from the various green spaces. e literature data made it possible to take stock of green spaces, in particular their characteristics and their standard. e floristic inventory is based on the identification of all species in the green space, the counting and measurement of woody DBH (DBH ≥ 10 cm). e parameters monitored are frequency, density (number of individuals per unit area), DBH (diameter at breast height), basal area (ST), and anthropogenic effects. e inventory of facilities concerns those intended for rest, leisure, historical, and/or cultural monuments present in each green space. e location of the benches in relation to the vegetation cover (under shade and/or exposed to the sun) was also taken into account.

Expression of Phytoecological Results
(i) Frequency: number of surveys where the taxon is present relative to the total number of surveys (ii) Shannon diversity index: H′ � − S i�1 pi · ln pi with pi � ni/n (ni � number of individuals of species "i"; n � total number of individuals of all species) (iii) Maximum diversity index: H ′ max � ln(S) with S � total species (iv) Equitability and/or regularity index (from Pielou): Eq � H ′ /H max ′ (v) Jaccard similarity coefficient (%) � 100 × (nc/ (na + nb − nc)) with na � number of specimens from survey a; nb � number of specimens from survey b; and nc � number of specimens common to both surveys

Location and Status of Green Spaces in Brazzaville.
Green spaces currently cover a very small total area of almost 13 ha or 0.04% of the urban area of Brazzaville (Table 1). ere were 9 green spaces located exclusively in two townships (Bacongo and Poto-Poto) while the city of Brazzaville comprises 9 townships. ese green spaces are divided, according to the floristic facies, into 2 types: green areas with trees and green areas without trees (Table 1).     e similarity coefficient of Jaccard and woody flora, between green spaces varies from 0 to 41.66%.

Floristic
is data reveals that the floristic composition is very heterogeneous from one medium to another (Table 1). It would be the corollary of the invasion of the allochthonous flora in the urban arboriculture in Brazzaville.
e average Shannon biodiversity index for the 9 green spaces is 0.96 ± 0.14 ( Table 1). e values range from 0.21 to 1.94. e maximum diversity achieved by these formations is 1.48 ± 0.13 on average, for an average range of 1.03 to 2.30.
e Pielou index is 0.66 ± 0.06 on average, with a range of numbers oscillating from 0.13 to 0.85. On the whole, these data mark the paucispecific and paucifloristic characters of the mentioned green spaces.

Tree Basal Area in the Green Spaces of Brazzaville.
e projection of trunk sections on the ground per green space of at least 1 ha varies from 0.31 to 3.86 m 2 ·ha − 1 (Figure 3). However, for those less than 1 ha, the value is between 0.26 and 5.25 m 2 per green space.

Diametric Structure of Trees in Brazzaville' Green
Spaces.
e diametric structure of ligneous trees is declined in  erratic curves, for all species, notwithstanding their status as aesthetic and key factor of the well being of the green space ( Figure 4). is structure denotes a natural regeneration deficit and the ageing of the stand following (i) the nonreplacement of the elderly subjects and (ii) letting nature do its work.

Benches and Location.
e inventory shows 188 benches, an average of 20.89 ± 3.95 per green space. Depending on their location, 63.83% of the resting facilities are exposed to the sun all day long, compared with the tree crown.
is rate corresponds to an average of 13 ± 3.33 benches per green space. However, 36.17% benefit, at least partially, from the shade of woody trees during the day, either 8 ± 1.7 benches per green space on average. (Figure 5).

Playgrounds and Historical
Monuments. Only 4 of the 9 green spaces studied have some leisure facilities and historic monuments ( Figure 6). e presence rates of leisure facilities (sports field and other games) per green space are as follows: 7.5% at Pierre Savorgnon De Brazza garden and 25% at the Faculty of Science and Technology square. Historical and/or cultural monuments represent 33.33%. Brazzaville green spaces are clearly underequipped and remain well away from international standards.  International Journal of Ecology 7 between exponential urbanization and the installation of green spaces (Table 3)

Green Spaces and Biodiversity.
e floral analysis of green spaces in Brazzaville proves that these very paucispecific environments are also very poor floristically.
is double weakness would correlate with the erosion of biodiversity caused by the drastic regression of natural urban and periurban forests [8,40]. is degradation of green spaces in Brazzaville does not allow these entities to provide goods and services that are vested in them [4,9,[13][14][15][16]. e preponderance of exotic species, especially shrubs, does not guarantee the conservation and enhancement of the local flora [40]. A comparison of the specific and floristic diversity of green spaces and periurban forests in Brazzaville shows that they are more diversified [8,[41][42][43][44][45]. However, most of their taxa are not present in green spaces. Considering that these green spaces have not been monitored, integrating the conservation dimensions of plant biodiversity, both local and exotic, and the extent of the area, since independence, it is difficult to make a decision on any correlation between these two parameters, despite some variations in the floristic composition.

Green Spaces and Quality of Life.
e very low level of equipment, stricto sensu, of green spaces in Brazzaville coupled with the projection of sections of trunks on the ground, are elements that do not allow green spaces to fully play their ecological, environmental, and recreational functions [9,12,13,17,23,46]. Under a hot and humid climate, the city of Brazzaville is unable to mitigate the impacts of climate change (climate variability and quasipermanent heat waves and persistence of parasitic and vector-borne diseases) and air pollution by suspended particles, greenhouse gases, and metallic trace elements. Facilities such as playgrounds and sports facilities are crossroads for people from different social backgrounds, ethnicities, races, and generations (from young children to the elderly).

Green Spaces and Health.
e low representativeness of green spaces throughout the city of Brazzaville, and the absence of green spaces in several boroughs, force the populations to live enclosed in dwellings or plots that are, for the most part, poorly developed. us, the green spaces of the city of Brazzaville do not offer the city dwellers the ideal conditions for evacuating daily stress and mitigating the psychological effects associated with occupational turpitudes and vicissitudes, various ailments such as musculoskeletal disorders, respiratory problems and migraines [18][19][20][21][22][23]. If these green spaces covered a sufficient area, they would not only encourage the practice of collective games, thus socializing, would ward off the risks of obesity associated with sedentarization [24,[49][50][51][52][53]. is would reduce the budget devoted to health by the State and the population [4]. Optimizing the benefits of green spaces is to have them as close as possible to homes. Lessard and Boulfroy [54] estimate that a better response on quality of life and a marked reduction in medical care is achieved within a 500 m radius.

Combating the Effects of Climate
Change. Global climate change affecting planet earth is not a marginal phenomenon in the Congolese context, as noted in the work of Bouka Biona and Mpounza [55], Samba and Nganga [33], and Samba et al. [34]. From these studies, the climatic impact is expressed in an increase in temperature and precipitation over almost the entire territory, despite some variations. Changing these two parameters inexorably affects biodiversity and with it the dynamics and functioning of ecosystems [56]. e vegetation cover of the green spaces of Brazzaville is very low to mitigate the effects of the urban heat island and pollution generated by the city, on the one hand [5,6,9,16,57,58]. On the other hand, reducing carbon and other greenhouse gas emissions to combat global warming has become a global issue [9]. However, DBH is a very important parameter in the evaluation of carbon sequestered by trees via allometric equations. e higher the DBH, the more important the biomass, the more carbon sequestered the tree [6,9,59,60]. At a time when the majority of trees in green spaces are senescent, their carbon sequestration power and/or capacity remain very limited.
Most of the trees in the green spaces of Brazzaville have modest DBH, they are stands that have aged, and have reached a point of equilibrium for carbon absorption. As stands approach maturity, growth rates and carbon uptake decrease [9,61]. ese trees, which currently require more maintenance energy than for their growth, are characterized by a very low carbon sequestration capacity.
Because of the long life of these trees and their relatively large dimensions, these trees are true carbon stores and not carbon sinks [60]. Currently with the obvious impoverishment of citizens, green spaces have become essential elements of the traditional phytotherapeutic system, sources of wood energy, and wood crafts [62]. e majority of trees is barked and has senescence cavities. e exploitation of these virtues exposes the internal organs to attacks by microorganisms (cryptogamic), the corollaries of which are decay and the release of carbon sequestered in the atmosphere [62][63][64][65][66]. us, the fight against global climate change is not really ensured by the green spaces in Brazzaville, because their contribution is rather noted as a source of carbon emissions.

Efforts to Be Made in the Creation of Green Spaces.
Despite the benefits of green spaces, which are no longer to be demonstrated, Brazzaville does not take this dimension into account in its urban planning [4]. e clear proof is that not all boroughs, new or old, have green spaces or even a reserved area in the various master urban plans. is lack of interest is reflected in the existence of the same green spaces dating from colonial times, some of which have had varying fortunes. Unless they disappear like that of the Maya-Maya Airport, they see their surface area greatly reduced like the Schoelcher area [28,67]. Despite the presence of the environmental, hygiene, and quality-of-life services that exist in the town halls, the green spaces in Brazzaville have remained a colonial fact, in the eyes of the city's new managers. Indeed, we are far from meeting the internationally accepted standard of 10 m 2 of green space per citizen in urban areas and 25 m 2 in periurban areas [4,7,38,39]. is observation also applies to the avenue and/or alignment trees, which together inspired the name "Brazza la verte."

Conclusion
In the city of Brazzaville, the areas devoted to green spaces are very small. us, the green space/population ratio is almost zero, despite the international standard. e existing green spaces date from the colonial period and see their surface regressed, if they have not disappeared. Set up at a time when the city was born, all the green spaces are concentrated in the oldest townships of the city, although this one knew an important development during the last thirty years. is situation does not allow the entire population of Brazzaville to benefit directly or indirectly from green spaces. e need for green space is essential in urban areas, especially those with low incomes, as it helps to reduce health costs.
Brazzaville must develop and significantly increase the proportion of vegetated surface, taking into account the different needs of its population. us, urbanization policy should integrate the green space dimension for the well being of all, in order to meet the international standards of 21 st century urban cities. is policy will involve a rational and equitable rebalancing of local biodiversity conservation issues, environmental balances, recreational needs, and other associated values. Finally, our green spaces imperatively require developments oriented towards the replacement of all old trees with a preference for indigenous diversity on the other hand.
is vision would lead the capital city to clearly fit into a policy to combat global climate change, by increasing carbon sequestration and improving the quality of life of urban and periurban populations.