Abstract
Urban forests are responsible for a lot of benefits, and can be used as a tool to ex-situ conservation of native species. Our study investigated a public urban forest aiming to provide subside to management projects in order to allow the accurate fulfillment of social, aesthetic and ecological functions displayed by trees. Our survey was conducted in 6 public squares and 5 gardens in the Jardins neighborhood. We classified the trees according to their phytogeographic origins and seed dispersal habit. The Shannon-Weaver (H’) index, Simpson’s dominance (D’) and Pielou’s equability (J) were determined. A total of 507 individuals were sampled, located in 12 botanical families and 29 species, and 13 of them were classified as native and 16 as exotic. The family with higher species richness and number of species was Fabaceae (36%). Regarding the seed dispersal syndrome, the most representative was zoochory (52%). The ecological index showed medium species diversity (H’=2.2284), high dominance (D’=0.7899) and medium number of individuals (J) 0.6552. Although the Jardins neighborhood was planned, the urban forest in this area still needs improvement; such as incentive measures that can promote biodiversity and the application of ex-situ conservation.
Keywords:
phytosociology; planned neighborhood; urban conservation; urban forests
Resumo
As florestas urbanas apresentam infinidades de benefícios, podendo atuar como uma ferramenta para conservação ex-situ. O estudo teve como objetivo realizar o diagnóstico de uma floresta urbana pública, com o intuito de oferecer subsídios para o manejo e garantir que a arborização possa cumprir com funções sociais, estéticas e ecológicas. O levantamento foi desenvolvido em 6 praças e 5 canteiros centrais do Bairro Jardins. As espécies foram classificadas quanto a sua origem fitogeográfica e forma de dispersão de sementes. Foram determinados os índices de diversidade de Shannon-Weaver (H’), dominância de Simpson (D’) e equabilidade de Pielou (J). Ao todo foram identificados 507 indivíduos, pertencentes a 12 famílias e distribuídos em 29 espécies, sendo 13 nativas e 16 exóticas. A família que apresentou maior riqueza em número de espécies foi a Fabaceae (36%). Quanto à classificação da síndrome de dispersão, a mais ocorrente foi por zoocoria (52%). Os índices ecológicos calculados do bairro mostraram ocorrência de média diversidade de espécies (H’ = 2.2284), dominância elevada (D’ = 0.7899) e médio equilíbrio do número de indivíduos (J) de 0.6552. Embora o bairro Jardins tenha sido planejado, a floresta urbana nessa área ainda precisa de melhorias; tais como medidas de incentivo que podem promover a biodiversidade e a aplicação de conservação ex-situ.
Palavras-chave:
fitossociologia; bairros projetados; florestas urbanas; conservação urbana
Introduction
Urban forests can be defined as a group of vegetation situated in the urban perimeter, which includes public and private areas such as forests, public squares, residential gardens, street trees and green areas in general and usually are composed by isolated or grouped trees. The presence of urban forests promotes an infinity number of aesthetic, social and ecological benefits, and contributes to a better air quality and hydric balance, increasing the thermal comfort, decreasing the noise pollution and wind speed, as well as visually harmonizing the environment, being used as passive bio-monitors of environmental pollution (Cardoso et al., 2017CARDOSO, K.M.; PAULA, A.; SANTOS, J.S.; SANTOS, M.L.P. Uso de espécies da arborização urbana no biomonitoramento de poluição ambiental. Ciência Florestal, v.27, n.2, p.535-547, 2017. http://dx.doi.org/10.5902/1980509827734
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).
The urbanization process contributes to a decrease in the richness of native species, and can reduce the ecological aspect of trees, especially in the Caatinga and Atlantic Forest biomes, which are highly anthropized. Streets that holds the presence of native trees are a key element in providing food for the local fauna and contributes to the genetic fluxes by forming ecological corridors in the landscape (Kolbe et al., 2016KOLBE, S.E.; MILLER, A.I.; CAMERON, G.N.; CULLEY, T.M. Effects of natural and anthropogenic environmental influences on tree community composition and structure in forests along an urban-wildland gradient in southwestern Ohio. Urban ecosystems, v.19, n.2, p.915-938, 2016. http://dx.doi.org/10.1007/s11252-016-0531-7
http://dx.doi.org/10.1007/s11252-016-053...
; Lynch, 2019LYNCH, A.J. Creating effective urban greenways and stepping-stones: four critical gaps in habitat connectivity planning research. Journal of Planning Literature, v.34, n.2, p.131-155, 2019. http://dx.doi.org/10.1177/0885412218798334
http://dx.doi.org/10.1177/08854122187983...
). In addition, urban forests are capable of cushioning the impact of urban areas in adjacent natural areas, particularly flagrant when taking in consideration the diversity and richness of its composition (Sartori et al., 2019SARTORI, R.A.; MARTINS, G.A.C.; ZAU, A.S.; BRASIL, L.S.C. Urban afforestation and favela: a study in a community of Rio de Janeiro, Brazil. Urbana Forestry & Urban Greening, v.40, p.84-92, 2019. http://dx.doi.org/10.1016/j.ufug.2018.10.004
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).
Brazil is internationally recognized as a mega diverse country (Moro and Castro, 2014MORO, M.F.; CASTRO, A.S.F. A check list of plant species in the urban forestry of Fortaleza, Brazil: where are the native species in the country of megadiversity? Urban Ecosystems, v.18, n.1, p.47-71, 2014. http://dx.doi.org/10.1007/s11252-014-0380-1
http://dx.doi.org/10.1007/s11252-014-038...
), but there is still a high utilization of exotic species in urban forest projects, with many of them being considered as invasive species (Brun et al., 2017BRUN, F.G.K.; BRUN, E.J.; LONGHI, S.J.; GORENSTEIN, M.R.; MARIA, T.R.B.C.; REGO, G.M.S.; HIGA, T.T. Vegetação arbórea em remanescentes florestais urbanos: Bosque do Lago da Paz, Dois Vizinhos, PR. Pesquisa Florestal Brasileira, v.37, n.92, p.503-512, 2017. http://dx.doi.org/10.4336/2017.pfb.37.92.140
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). According to Coelho Jr. et al. (2019COELHO JUNIOR, W.P.; LEITE, C.E.A.M.; BARBOSA, F.S.Q.; BENDINI, J.N.; PACHECO, A.C.L.; ABREU, M.C. Espécies utilizadas na arborização das vias públicas do bairro centro na cidade de Picos-PI. Journal of Environmental Analysis and Progress, v.4, n.3, p.209-215, 2019. 10.24221/jeap.4.3.2019.2512.209-2015
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), replacing native for exotic species is a recurrent practice utilized in public areas, which leads to alterations in the remaining natural environments in urban zones. This practice also contributes to the homogenization of the landscape in public areas and decreases the diversity of flora and fauna. In this sense, it is necessary to invest continually in the maintenance of the urban forests (Kowarik et al., 2019KOWARIK, I.; HILLER, A.; PLANCHUELO, G.; SEITZ, B.; VON DER LIPPE, M.B.S. Emerging urban forests: opportunities for promoting the wild side of the urban green infrastructure. Sustainability, v.11, p.6318, 2019. http://dx.doi.org/10.3390/su11226318
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) by promoting landscape analysis and floristic composition studies in order to accomplish the desirable ecological benefits.
It is possible to use adequate urban forestry techniques as an ex-situ tool to preserve the native trees by utilizing them as ornamental elements, representing the local biodiversity and increasing opportunities to create awareness about the native flora to conserve and preserve those species (Moro and Castro, 2014MORO, M.F.; CASTRO, A.S.F. A check list of plant species in the urban forestry of Fortaleza, Brazil: where are the native species in the country of megadiversity? Urban Ecosystems, v.18, n.1, p.47-71, 2014. http://dx.doi.org/10.1007/s11252-014-0380-1
http://dx.doi.org/10.1007/s11252-014-038...
). In this sense, our study aims to evaluate a public urban forest in a residential neighborhood in order to provide subsidy to management and conservation projects, ensuring that those urban forests fulfill their social and aesthetic functions, as well as guaranteeing its ecological functioning. We tested the following questions: i) the native tree species are being prioritized in urban forest projects? ii) Is there species diversity in the composition of this forest? and iii) This urban forest can be considered a food resource for the local fauna?
Material and methods
Our study was conducted in the Jardins, a planned neighborhood located in São Gonçalo do Amarante municipality, in the metropolitan area of Natal, the capital of Rio Grande do Norte State. The area is situated in the mesoregion of the East Potiguar (Figure 1). According to IBGE (2019IBGE - Instituto Brasileiro de Geografia e Estatística. 2019. Available at: Available at: https://cidades.ibge.gov.br/brasil/rn/sao-goncalo-do-amarante/panorama . Acessed on: May15th2020.
https://cidades.ibge.gov.br/brasil/rn/sa...
), the municipality range is 249.800 km², with 14 neighborhoods, and a total population of 102 thousand of inhabitants and a total of 12.8% of forested area in public spaces.
The climate in the region is characterized as type A of Köppen, i.e. warm and humid tropical, with two distinct seasons: dry winters and rainy summers. The mean annual temperature is 26 ºC, the relative air humidity is 76%, with a mean annual precipitation of 1140 mm. The main phytophysiognomies in the area are Caatinga and Atlantic Forest (Alvares et al., 2014ALVARES, C.A.; STAPE, J.L.; SENTELHAS, P.C.; GONÇALVES, J.L.M.; SPAROVEK, G. Köppen’s climate classification map for Brazil. Meteorologische Zeitschrift, v.22, n.6, p.711-728, 2014. http://dx.doi.org/10.1127/0941-2948/2013/0507
http://dx.doi.org/10.1127/0941-2948/2013...
; IBGE, 2019IBGE - Instituto Brasileiro de Geografia e Estatística. 2019. Available at: Available at: https://cidades.ibge.gov.br/brasil/rn/sao-goncalo-do-amarante/panorama . Acessed on: May15th2020.
https://cidades.ibge.gov.br/brasil/rn/sa...
).
The floristic survey of the trees was carried in public spaces, totalizing 6 squares and 5 green traffic islands in the main avenues of the Jardins neighborhood, in May 2018 (Figure 2). The total area and the geographic coordinates of each environment were determined utilizing the software Google Earth.
The trees were visually identified according to the species level and their scientific or common etymology name were registered. Samples of flowers, fruits, and leaves from the unknown species were collected, pictures were taken and their individual morphological characteristics (such as bark color, vegetative and reproductive characteristics) were registered for posterior identification by a specialist. All the species sampled were placed in the Herbarium of Universidade Federal do Rio Grande do Norte (APG, 2016ANGIOSPERM PHYLOGENY GROUP (APG). An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Botanical Journal of the Linnean Society, v.181, p.1-20, 2016. https://doi.org/10.1111/boj.12385
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).
The species in our survey were classified according to their phytogeographical origins (native from Brazil or exotic) and dispersal syndrome in three categories: anemochoric (wind dispersion), zoochoric (animal dispersion) and autochoric (self-dispersion). We determined the district’s phytosociological parameters and its subdivisions (squares and public gardens) by calculating the absolute density, absolute frequency and relative frequency. The Shannon-Weaver diversity index, Simpson’s dominance and Pielou’s equability index were also calculated (Table 1).
Formulas used to determine the phytosociological parameters of the floristic composition of the Jardins neighborhood. N = total number of individuals; ni = number of individuals per species; S = number of species; A = area.
All the data sampled was tabulated and submitted to descriptive statistical analysis to determine: i) families and species that are usually utilized; ii) proportion of exotic and native species and iii) the predominant dispersion syndrome in the region. All the tables and graphics were developed utilizing the statistical program Microsoft Excel® 2016 version.
Results and discussion
The floristic composition and urban afforestation of the public squares and gardens at Jardins neighborhood presented 507 individuals, from 12 botanical families and distributed in 29 species: 13 of them were classified as native species and 16 were classified as exotic (Table 2).
List of families (in alphabetical order) and species sampled in the floristic survey of urban forestry in the Jardins neighborhood, São Gonçalo do Amarante-RN, Brazil. CN= Common etymology name; N= native; E= exotic; O= origin; AF= absolute frequency; RF= relative frequency (% of total individuals sampled); SD= ways of seed dispersal; ZOO= Zoochoric; ANE= Anemochoric; AUT= Autochoric; NI = Not identified.
According to Milano and Dalcin (2000MILANO, M.S.; DALCIN, E.C. Arborização de vias públicas. Rio de Janeiro: Light, 2000. 226p.), the ideal composition for an urban forest should include more than 20 species, while the minimum acceptable is 10 species. In this sense, the Jardins neighborhood fits the authors recommendations authors. Urban forests with a high number of species are becoming a useful tool for ex-situ conservation, since they provide an increased number of food resources to the animals in those areas (Pinheiro et al., 2018PINHEIRO, R.T.; MARCELINO, D.G.; MOURA, D.R. Espécies arbóreas de uso múltiplo e sua importância na conservação da biodiversidade nas áreas verdes urbanas de Palmas, Tocantins. Desenvolvimento e Meio Ambiente, v.49, p.264-282, 2018. http://dx.doi.org/0.5380/dma.v49i0.59315
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). It is important to highlight that an increased number of trees in these regions affect positively the human well-being (Carrus et al., 2015CARRUS, G.; SCOPELLITI, M.; LAFORTEZZA, R.; COLANGELO, G.; FERRINI, F.; SALBITANO, F.; AGRIMI, M.; PORTOGHESI, L.; SEMENZATO, P.; SANESI, G. Go greener, feelbetter? The positive effects of biodiversity on the well-being of individuals visiting urban and peri-urban green areas. Landscape and Urban Planning, v.134, p.221-228, 2015. http://dx.doi.org/10.1016/j.landurbplan.2014.10.022
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).
The families Fabaceae (36%), Anacardiaceae (14%) and Bignoniaceae (11%) were the ones with higher species richness and species number, totalizing 67% of the trees sampled (Figure 3). The predominance of the use of species from these families is commonly found in other regions, as observed in studies carried out by Moussa et al. (2020MOUSSA, S.; KUYAH, S.; KYEREH, B.; TOUGIANI, A.; MAHAMANE, S. Diversity and structure of urban forests of Sahel cities in Niger. Urban Ecosystems, v.23, n.4, p.851-864, 2020. http://dx.doi.org/10.1007/s11252-020-00984-6
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) when analyzing the urban forests from the cities Niamey and Maradi in Nigeria, with higher species number from the Fabaceae family. Silva et al. (2019aSILVA, A.D.P.; BATISTA, A.C.; GIONGO, M.V.; BIONDI, D.; SANTOS, A.F.; OLIVEIRA, L.M.; CACHOEIRA, J.N. Arborização das praças de Gurupi-TO - Brasil: composição e diversidade de espécies. Revista da Sociedade Brasileira de Arborização Urbana , v.14, n.4, p.1-12, 2019a. http://dx.doi.org/10.5380/revsbau.v14i4.67547
http://dx.doi.org/10.5380/revsbau.v14i4....
), when analyzing the public squares from the Gurupi municipality in Tocantins State, Brazil, found a predominance of individuals from Fabaceae and Anacardiaceae families, while Fernandes et al. (2018FERNANDES, C.J.; FERRAZ, M.V.; GIMENES, R.; PEREIRA, S.T.S.; PIVETTA, K.F.L. Trees description in the main square of São José do Rio Preto, São Paulo State, Brazil. Ornamental Horticulture, v.24, n.4, p.334-340, 2018. http://dx.doi.org/10.14295/oh.v24i4.1151
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) found a predominance of Fabaceae and Bignoniaceae families when analyzing the most popular square in São José do Rio Preto municipality, São Paulo State, also in Brazil.
Percentage of the number of species as to their origin within the families sampled in the floristic assessment of urban forestry in Jardins neighborhood, São Gonçalo do Amarante-RN, Brazil.
Fabaceae is one of the most representative families of Angiosperms, with approximately 19 thousand species and 727 genera (APG, 2016ANGIOSPERM PHYLOGENY GROUP (APG). An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Botanical Journal of the Linnean Society, v.181, p.1-20, 2016. https://doi.org/10.1111/boj.12385
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). In our study it was possible to evidence that there was an equilibrium regarding the presence of individuals from the Fabaceae family, with 5 of them being classified as native and 5 as exotic species. Trees from the Fabaceae family are commonly utilized in urban forests in Brazilian cities (Fernandes et al., 2018FERNANDES, C.J.; FERRAZ, M.V.; GIMENES, R.; PEREIRA, S.T.S.; PIVETTA, K.F.L. Trees description in the main square of São José do Rio Preto, São Paulo State, Brazil. Ornamental Horticulture, v.24, n.4, p.334-340, 2018. http://dx.doi.org/10.14295/oh.v24i4.1151
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; Silva et al., 2019SILVA, O.H.; LOCASTRO, J.K.; SANCHES, S.P.; ANGELIS NETO, G.; ANGELIS, B.L.D.; CAXAMBU, M.G. Avaliação da arborização viária da cidade de São Tomé, Paraná. Ciência Florestal, v.29, n.1, p.371, 2019. http://dx.doi.org/10.5902/1980509824889
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; Toledo et al., 2021TOLEDO, J.A.M.; PEREIRA, B.C.V.; MATTIUZ, C.F.M.; AMBROSANO, M.N.; CÁSARES, M.C.; SILVA, A.G.T.; FERRAZ, M.V. History, landscape, and botanical report of a centenary square in Brazil. Ornamental Horticulture, v.27, n.2, p.162-172, 2021. http://dx.doi.org/10.1590/2447-536x.v27i2.2266
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). Among the reasons for the wide use of species from the Fabaceae family are: the canopy architecture (shade from the tree), the presence of colorful inflorescences, aesthetic beauty, and easy seed dispersal, which increase the spontaneous emergence of new individuals, as well as the use of those trees by local inhabitants of a given area, which also increases the seedling of new individuals (Cabreira and Canto-Dorow, 2016CABREIRA, T.N.; ANTO-DOROW, T.S. Florística dos componentes arbóreo e arbustivo do campus da Universidade Federal de Santa Maria (UFSM), Santa Maria, RS. Ciência e Natura, v.38, n.1, p.9-23, 2016. http://dx.doi.org/10.5902/2179460X19022
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).
The Anacardiaceae family is mainly utilized due to the fact that they provide edible fruits, which is widely known by the local inhabitants. However, species such as Mangifera indica L. and Anacardium occidentale L., from the aforementioned family, are not considered as adequate for urban areas like public squares and avenues, as the trees are too big, with long roots, present canopies with heterogeneous shape and might promote accidents with their fruits, which can cause damage to urban areas such as sidewalks, electric wiring and the obstruction of manholes, as well as the unpleasant smell of decomposing fruits (Oliveira et al., 2018OLIVEIRA, A.F.; NEVES, C.L.P.; PEREIRA, G.A.; GARCIA, F.H.S.; COELHO, S.J.; PEREIRA, J.A.A. Floristics of road forestry conflicting with the electrical networks: a case study in the southern region of Minas Gerais state. Ornamental Horticulture, v.24, n.3, p.277-284, 2018. http://dx.doi.org/10.14295/oh.v24i3.1239
http://dx.doi.org/10.14295/oh.v24i3.1239...
; Silva et al., 2019SILVA, O.H.; LOCASTRO, J.K.; SANCHES, S.P.; ANGELIS NETO, G.; ANGELIS, B.L.D.; CAXAMBU, M.G. Avaliação da arborização viária da cidade de São Tomé, Paraná. Ciência Florestal, v.29, n.1, p.371, 2019. http://dx.doi.org/10.5902/1980509824889
http://dx.doi.org/10.5902/1980509824889...
).
The total of exotic trees was also superior to the total of native trees, with 54% and 46%, respectively. The use of exotic species in urban forests in Brazilian municipalities is a common practice (Freitas et al., 2020FREITAS, W.K.; MAGALHÃES, L.M.S.; SANTANA, C.A.A.; PEREIRA JUNIOR, E.R.; SOUZA, L.C.M.; TOLEDO, R.A.B.; GARÇÃO, B.R. Tree composition of urban public squares located in the Atlantic Forest of Brazil: a systematic review. Urban Forestry & Urban Greening, v.48, p.126555, 2020. http://dx.doi.org/10.1016/j.ufug.2019.126555
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), and can be justified by the lack of information about native species, as well as lack of planning and due to the need for rapid construction of green areas that are capable to provide thermal comfort and wellbeing for the human population. This also occurs in cities from the Amazon Domain, one of the most biodiverse areas of the world, where there is a wide usage of exotic species in urban areas due to the fact that the population acts as an enhancer of the urban forest, without the proper monitoring from the public sector (Vieira and Panagopoulos, 2020VIEIRA, T.A.; PANAGOPOULOS, T. Urban forestry in Brazilian Amazonia. Sustainability, v.12, n.8, p.3235, 2020. http://dx.doi.org/10.3390/su12083235
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).
The inadequate utilization of exotic invasive species in urban forest projects like public squares, woods, parks and avenues, can lead to a series of problems, like the alteration of the vegetation structure of the community, nutrient cycling and, as a more drastic consequence, can lead to losses in the biodiversity.
In a recent review conducted by Isernhagen et al. (2009ISERNHAGEN, I.; LE BOURLEGAT, J.M.G.; CARBONI, M. Trazendo a riqueza arbórea regional para dentro das cidades: possibilidades, limitações e benefícios. Revista da Sociedade Brasileira de Arborização Urbana, v.4, v.2, p.117-138, 2009. http://dx.doi.org/10.5380/revsbau.v4i2.66277
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) regarding the advantages of using regional native species in public spaces, we can highlight that the utilization of those trees can be a great tool to maintain the ex-situ genetic pool of native tree populations, as well as providing food and shelter for the local fauna, which contributes to the continuity of the genetic fluxes. Besides, it can also contribute to the ecological re-education of the local population by providing direct contact with the original vegetation of the area. In general, utilizing those species might promote the ex-situ conservation, leading to the conservation of non-natural populations, which is mainly important for species that are at risk of extinction such as Paubrasilia echinata (Pau Brasil), present our study area, which is categorized as endangered according to the red book of the flora of Brazil (Martinelli and Moraes, 2013MARTINELLI, G.; MORAES, M.A. Livro vermelho da flora do Brasil. Rio de Janeiro: Andrea Jakobsson, Instituto de Pesquisas Jardim Botânico do Rio de Janeiro, 2013. 1100p. ).
Nevertheless, it is important to highlight that the utilization of exotic species in urban forests shouldn’t be considered as only harmful, as they can help to improve quality of life for the inhabitants of a certain areas, as well as providing ecological and economic benefits for the human population (Davis et al., 2011DAVIS, M.A.; CHEW, M.K.; HOBBS, R.J.; LUGO, A.E.; EWEL, J.J.; VERMEIJ, G.J.; BROWN, J.H.; ROSENZWEIG, M.L.; GARDENER, M.R.; CARROLL, S.P. Don’t judge species on their origins. Nature, v.474, n.7350, p.153-154, 2011. http://dx.doi.org/10.1038/474153a
http://dx.doi.org/10.1038/474153a...
; Riley et al., 2017). However, the utilization of exotic species in urban areas must be planned aiming to reduce the risks of them becoming invasive. Milano and Dalcin (2000MILANO, M.S.; DALCIN, E.C. Arborização de vias públicas. Rio de Janeiro: Light, 2000. 226p.) also emphasize that in urban forest projects it is important that each of the species utilized don’t outreach 15% of the total of individuals in a population, avoiding risks of losing the local biodiversity.
The Meliaceae family, represented in our study mainly by Azadirachta indica A. Juss, also known as Nim, was one of the most representative trees, accounting for 40.2% of the species sampled and being present in 4 public squares and 5 public gardens. According to Moro et al., (2013MORO, M.F.; WESTERKAMP, C.; MARTINS, F.R. Naturalization and potential impact of the exotic tree Azadirachta indica A. Juss. in Northeastern Brazil. Check List, v.9, n.1, p.153-156, 2013. https://doi.org/10.15560/9.1.153
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) A. indica is a popular species generally utilized in urban forest projects in public streets in the northeast region in Brazil. The species is well distributed in warm, dry areas with soils that are well drained, which makes the northeast region a potential area for its occurrence (Neves, 2004NEVES, E.J.M. Importância dos fatores edafo-climáticos para o uso do Nim (Azadirachta indica A. Juss) em programas florestais e agroflorestais nas diferentes regiões do Brasil. Colombo: Embrapa Florestas, 2004. p.99-107.).
Due to the favorable conditions and rapid growth, A. indica plants were introduced by many city councils in order to increase the shaded areas in public avenues. However, in the past few years the frequency of utilization of A. indica in urban forests is increasing, mainly due to the fact that this species is becoming more popular with the local inhabitants. A. indica is a natural bug repellent, and is also considered as an ornamental plant, and those characteristics made this species the favorite one to be planted by the local population.
However, the use of A. indica can cause many problems such as pipe obstructions, damage to the electric wiring, and there’s a need of constantly trimming the branches. Recently, there were a few studies that indicated that A. indica has a potential to be an invasive species (Ansong et al., 2019ANSONG, M.; PERGL, J.; ESSL, F.; HEJDA, M.; VAN KLEUNEN, M.; RANDALL, R.; PYSEK, P. Naturalized and invasive alien flora of Ghana. Biological Invasions, v.21, p.669-683, 2019. http://dx.doi.org/10.1007/s10530-018-1860-7
http://dx.doi.org/10.1007/s10530-018-186...
; Santos and Kiwango, 2010SANTOS, A.S.; KIWANG, H. Management of invasive plants in tropical forest ecosystems: trial of control methods of Azadirachta indica. World Applied Science Journal, v.10, n.2, p.1414-1424, 2010. ), which leads to the need of taking preventive measures when utilizing this species in the urban afforestation, like monitoring the seedlings, removing and/or substituting the trees from A. indica growing near protected natural areas (Moro et al., 2013MORO, M.F.; WESTERKAMP, C.; MARTINS, F.R. Naturalization and potential impact of the exotic tree Azadirachta indica A. Juss. in Northeastern Brazil. Check List, v.9, n.1, p.153-156, 2013. https://doi.org/10.15560/9.1.153
https://doi.org/10.15560/9.1.153...
).
The ecological indexes calculated to Jardins neighborhood (Table 3) indicate that there is a medium species diversity (H’ = 2.2284), with high dominance (D’ = 0.7899). We noticed the presence of 29 tree species being utilized in the afforestation of this neighborhood, but there is also a homogeneous distribution of those trees, where we could notice a high number of individuals from a few species. This can be highlighted when we observe the diversity between different localities (public squares and gardens) where the Shannon-Weaver index is lower. The avenue 3 and the public squares 3, 4 and 6 showed a high equability (J), with values close to 1 (Brower and Zar, 1984BROWER, J.E.; ZAR, J.H. Field and laboratory methods for general ecology. Dubuque: W.M.C. Brow, 1984. 226p.), indicating that only in these localities the species are in equilibrium regarding the number of individuals.
Phytosociological parameters of afforestation in the squares and green traffic islands (GTI) of Jardins neighborhood, São Gonçalo do Amarante-RN, Brazil. E (%) = Exotic; N (%) = Native; NI = Not identified; AD = Absolute Density; H ’= Shannon-Weaver index; D ‹= Simpson›s index; J = Pielou›s equability index.
The low species diversity can be changed by replacing the exotic species with high frequency, or even planting new seedlings of native species, since the locations analyzed in our study had a low absolute density (AD), which indicates the existence of spaces for new individuals to be planted in those areas. The existence of urban forests in public avenues and squares could act as ecological trampolines or steppingstones, promoting dynamism for the animal species, which are the major responsible for pollination and seed dispersion (Lynch, 2019LYNCH, A.J. Creating effective urban greenways and stepping-stones: four critical gaps in habitat connectivity planning research. Journal of Planning Literature, v.34, n.2, p.131-155, 2019. http://dx.doi.org/10.1177/0885412218798334
http://dx.doi.org/10.1177/08854122187983...
).
Piratelli et al. (2017PIRATELLI, A.J.; FRANCHIN, A.G.; MARÍN-GÓMEZ, O.H. Urban conservation: Toward bird-friendly cities in Latin America. In: MACGREGOR-FORS, I.; ESCOBARIBÁÑEZ, J. (Eds.). Avian ecology in Latin American cityscapes. Cham: Springer International Publishing AG, 2017. p.143-158.) highlights that the creation of greener cities with higher species biodiversity will benefit the wildlife, as well as positively impacting the human life, making the cities healthier and more pleasant to inhabit. It is also important to incorporate a diversified pool of native species in urban forests, because they can promote an increase in the ex-situ conservation of species, since those species are also capable of releasing different resources in different phenological periods of the year.
In the Jardins neighborhood, 52% of the species in a total of 331 individuals were classified as zoochory dispersed; 27% of the species with 41 individuals were wind dispersed and 21% of the 118 individuals were autochory dispersed (Figure 4). The dispersion syndrome is an important determinant to increase the population of a certain individual, increasing the survival and perpetuation of the species. By planning and managing the urban forests, the city of Belo Horizonte, in Brazil, could retain 20% of the birds inside the urban matrix (Pena et al., 2017PENA, J.C.C.; MARTELLO, F.; RIBEIRO, M.C.; ARMITAGE, R.A.; YOUNG, R.J.; RODRIGUES, M. Street trees reduce the negative effects of urbanization on birds. PLoS ONE, v.12, n.3, 2017. http://dx.doi.org/10.1371/journal.pone.0174484
http://dx.doi.org/10.1371/journal.pone.0...
).
Number of individuals in its exotic or native origin by the form of dispersion of the urban forestry in the Jardins neighborhood, São Gonçalo do Amarante-RN, Brazil.
Zoochory can be characterized as the dispersion promoted by animals, and is one of the most common dispersion syndromes among trees in tropical environments (Gomes, 2018GOMES, L.C. Síndromes de dispersão do estrato arbóreo-arbustivo em dois fragmentos florestais no Pantanal Sul, MS. Bidoverisidade, v.17., n.2, p.139-149, 2018. ). In urban forests the amount of vegetation cover positively influences the presence of native birds with different eating habits, mainly the granivores (Villasenor et al., 2021VILLASENOR, N.R.; ESCOBAR, M.A.H.; HERNÁNDEZ, H.J. Can aggregated patterns of urban woody vegetation cover promote greater species diversity, richness, and abundance of native birds? Urban Forestry & Urban Greening , v.61, 2021. http://dx.doi.org/10.1f016/j.ufug.2021.127102
http://dx.doi.org/10.1f016/j.ufug.2021.1...
), as well as the existence of complex/specific interactions between plants and pollinators, which makes this fact an important reason to utilize a higher diversity of native trees and increase the conservation of native species.
It is important to utilize native tree species aiming to increase the genetic fluxes of those individuals, taking in consideration their dispersion syndromes, as well as increasing the number of individuals in the urban forests and decreasing the predominance of exotic species (Siqueira, 2017SIQUEIRA, S.J.J.C. Dispersão de espécies nativas na arborização urbana. Pesquisas Botânica, v.70, p.187-195, 2017.). The existence of urban forests provides a myriad of ecosystem services, and it is important that the decision makers take in consideration planning ahead the urban forests by including landscape covers and local characteristics of the flora, reducing the habitat loss of native species and preventing the existence of risky areas in urban spaces (Smith et al., 2018SMITH, W.S.; SILVA, F.L.; AMORIM, S.R.; STEFANI, M.S. Urban biodiversity: how the city can do its management. Biodiversity International Journal, v.2, n.3, p.272-277, 2018. http://dx.doi.org/10.15406/bij.2018.02.00068
http://dx.doi.org/10.15406/bij.2018.02.0...
; Vieira and Panagopoulos, 2020VIEIRA, T.A.; PANAGOPOULOS, T. Urban forestry in Brazilian Amazonia. Sustainability, v.12, n.8, p.3235, 2020. http://dx.doi.org/10.3390/su12083235
http://dx.doi.org/10.3390/su12083235...
).
It is essential that the decision makers include competent staff from the forest industry in their management teams to implement urban forests in a sustainable way, increasing the social perception of the biodiversity as well as promoting the ex-situ conservation of native species. The decision makers should include environmental education, reforestation planning, and partnerships between the universities and the public sector in order to promote the urban conservation of native species (Vieira and Panagopoulos, 2020VIEIRA, T.A.; PANAGOPOULOS, T. Urban forestry in Brazilian Amazonia. Sustainability, v.12, n.8, p.3235, 2020. http://dx.doi.org/10.3390/su12083235
http://dx.doi.org/10.3390/su12083235...
). Carrying floristic surveys like our study is important to ensure the planning and subsidize management activities in urban forests.
Conclusions
Despite being a planned environment, the correct project and the implementation of the urban forest in public areas of this district (public squares and avenue gardens) were neglected, which could be proved by the usage of tree species that were inadequate for urban areas and the high number of exotic species. The study area presented a moderate diversity and can be considered a food source for the local fauna, once most of the individuals’ dispersal syndrome is the zoochory.
In addition, it is important to implement native trees that are adapted to the region when planning urban forests aiming the conservation of the ecosystem, such as increasing the number of Paubrasilia echinate individuals, as it is in danger of extinction, and inserting other species characteristic of the Caatinga and Atlantic Forest, the predominant biomes of the region. Native species indicated for urban afforestation represent a lower risk of accidents, less infrastructure problems, lower maintenance costs and increased genetic flows. By doing so, it is possible to perpetuate the life of those species and to promote ecological equilibrium in the environment, as the urban forest can accomplish certain social, aesthetic and environmental functions.
Acknowledges
We thank the Unidade Acadêmica Especializada em Ciências Agrárias from Universidade Federal do Rio Grande do Norte (UFRN) for providing financial support and laboratory facilities; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for providing financial support and the scholarship through the Programa Institucional de Bolsas de Iniciação Científica (PIBIC); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.
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» http://dx.doi.org/10.15406/bij.2018.02.00068 - TOLEDO, J.A.M.; PEREIRA, B.C.V.; MATTIUZ, C.F.M.; AMBROSANO, M.N.; CÁSARES, M.C.; SILVA, A.G.T.; FERRAZ, M.V. History, landscape, and botanical report of a centenary square in Brazil. Ornamental Horticulture, v.27, n.2, p.162-172, 2021. http://dx.doi.org/10.1590/2447-536x.v27i2.2266
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» http://dx.doi.org/10.3390/su12083235 - VILLASENOR, N.R.; ESCOBAR, M.A.H.; HERNÁNDEZ, H.J. Can aggregated patterns of urban woody vegetation cover promote greater species diversity, richness, and abundance of native birds? Urban Forestry & Urban Greening , v.61, 2021. http://dx.doi.org/10.1f016/j.ufug.2021.127102
» http://dx.doi.org/10.1f016/j.ufug.2021.127102
-
Area Editor: Lúcia Maria de Siqueira Cavalcanti Veras
Author Contribution
-
JGMUF: research project design, project methodology, data collection, data analysis and interpretation and writing; FMFL: analysis and interpretation of data and writing; DMA: data collection and writing; BRFS: data collection and writing; DMA: Illustrations; DYOB: critical review; TKBA: project methodology and critical review.
Publication Dates
-
Publication in this collection
14 Jan 2022 -
Date of issue
Jan-Mar 2022
History
-
Received
13 Apr 2021 -
Accepted
23 Sept 2021 -
Published
07 Oct 2021