Hyperdominance of exotic invasive trees in street afforestation of semi-arid Brazilian cities

Published: 30 June 2026| Version 2 | DOI: 10.17632/23z7rrkk88.2
Contributors:
Arleu Viana-Junior,

Description

Supplementary Material from the original research article entitled: “Hyperdominance of exotic invasive trees in street afforestation of semi-arid Brazilian cities”. Authors: Arleu B. Viana-Juniora, João Carlos Pena, Fernanda Kalina Da Silva Monteiro, Joselice da Silva Pereira, Rafaella Santana Santos, D’Ávilla Ruama Fernandes Lopes Gomes, Sérgio de Faria Lopes, Maria Avany Bezerra-Gusmão, Camile Dias Avelino, Bráulio Almeida Santos. ARTICLE INFORMATION: This study investigates the distribution, richness, and species composition of street trees in 10 semi-arid Brazilian cities, analysing the proportion of native and non-native species and the potential of these urban areas to support biodiversity. A total of 1,381 trees of 69 species were identified. About 80% of the individuals and 52% of the species were non-native. More concerning, approximately 60% of the individuals belonged to exotic invasive species; the Indian Neem alone, Azadirachta indica, accounted for 700 individuals. As expected, the increase in impervious surface cover negatively affected the native species richness. Five cities were classified as antagonistic for biodiversity due to the high proportion and dominance of non-native species. These findings reveal a concerning bias towards exotic invasive tree species in the studied Brazilian cities, potentially causing negative effects on the remaining urban biota.

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This study was performed in 10 cities in the state of Paraíba (7° 24' S; 36° 28' W), located in north-eastern Brazil . To investigate the street tree community in semiarid Brazilian cities, in each city, we selected four sites distanced at least 100 m between each other. In each site, we establish a 300 m long linear transect along sidewalks, median strips and other similar structures that allowed tree identification. In some sites, the transect had to be subdivided into two or three sections to fit the design of the streets, getting a ‘L’, '+', 'F' or 'T' shape. All woody individuals with a circumference at ground level greater than 10 cm were labeled and identified. We used circumference as a proxy of tree size and an indicative of planting management: small trees represented recent plantings, while large trees indicated older planting. The plant identification was performed by a botanical expert (FKSM) and through photographic records or in loco observation. When in loco identification was not possible, sterile and fertile parts (flowers and fruits) were collected and properly dried and stored for further identification. Plant identification followed the specialized literature (Flora and Funga of Brazil, 2024) and comparisons with specimens available on JSTOR Global Plants (https://plants.jstor.org/) and Species Link (https://specieslink.net/search/). With the species list finalized, we classified species as native, exotic, and/or invasive to Brazil using the Global Register of Introduced and Invasive Species (GBIF - https://www.gbif.org/), and the National Database of Invasive Alien Species (Instituto Hórus de Desenvolvimento e Conservação Ambiental - https://bd.institutohorus.org.br/especies).

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Plant Ecology, Urban Ecology, Afforestation

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