Efeito da urbanização na abudância e riqueza de invertebrados associados à turnera subulata na cidade de Fortaleza, Ceará

Abstract

Urbanization intensely modifies natural ecosystems, resulting in habitat loss, fragmentation, homogenization, and changes in ecological community structures. Despite the detrimental effects of urbanization, these environments can serve as refuges/islands for species. Thus, many species find in these fragments the conditions to survive despite the fragmentation caused by urbanization. This study aims to evaluate how different degrees of urbanization and plant structure affect the richness and abundance of invertebrates associated with Turnera subulata, a ruderal plant widely distributed in Brazilian urban environments. The study was conducted in 15 urban areas in the city of Fortaleza, in the state of Ceará, Brazil, where T. subulata was present. In each area, two 1m x 1m plots were established in locations with T. subulata, from which the plants were collected and stored in plastic bags, and the invertebrates associated with T. subulata were identified to the lowest possible taxonomic level. The degree of urbanization was assessed through manual land-use classification using satellite images in geoprocessing software (QGis). To assess the influence of urbanization, leaf number, and average branch length on the abundance and richness of invertebrates in T. subulata, we used a Generalized Linear Mixed Model (GLMM) with a negative binomial distribution in the R environment. A total of 121 T. subulata individuals were sampled, resulting in 3,393 invertebrates distributed across 97 species. The species Gargaphia lunulata was the most abundant among the analyzed invertebrates, while the family Thomisidae showed the highest richness. The Generalized Linear Mixed Model (GLMM) revealed that invertebrate abundance and richness were not influenced by the degree of urbanization, branch length, or leaf number. As for functional groups, pollinators and herbivores were not affected by urbanization or plant characteristics; however, predator abundance was negatively influenced by the degree of urbanization. Despite the detrimental effects of urbanization, the results indicated that urbanization did not significantly affect the abundance and richness of invertebrates associated with T. subulata. However, the reduction in predator abundance in urbanized areas reflects the sensitivity of these individuals to habitat fragmentation, abiotic homogenization, loss of food resources, and shelter. Thus, ruderal plants such as T. subulata can act as important refuges for invertebrate fauna, contributing to biodiversity maintenance in urban areas.