Ecological implications of twentieth century reforestation programs for the urban forests of São Paulo, Brazil: a study based on litterfall and nutrient cycling

Abstract

The focus of this study was to investigate the wide use of Eucalyptus spp., an exotic plant with high allelopathic ability, in the reforestation programs of urban parks in São Paulo City, Brazil, over the last century. To understand the implications of using Eucalyptus spp. in the city’s parks, this study aimed to compare nutrient cycling and litter decomposition between a mixed composition of litter (i.e., native and exotic species) and the litter of a single species (i.e., Eucalyptus). To accomplish this, newly deciduous leaves were collected from two native and two exotic species that are commonly used in the afforestation of São Paulo as well as from Eucalyptus spp. The mixed composition of litter yielded a higher dry mass loss and return of macro- and micronutrients to the forest floor. The decomposition constant (k) values were 0.00322 and 0.00207 g g−1 day−1 for the mixed composition and Eucalyptus spp., respectively. The time required for decomposition of 50 and 95% of deciduous material was 215 and 931 days, respectively, and for the mixed litterfall 334 and 1449 days, respectively, for Eucalyptus spp. Therefore, the mixed litter exhibited greater dry mass loss and nutrient cycling in an urban forest of São Paulo City, since dry mass losses as well as speed and amount of nutrients returned to the forest floor were relatively higher compared to Eucalyptus spp. Nutrient cycling via Eucalyptus spp. litter was less efficient than mixed composition of litter, demonstrating that reforestation programs carried out in the twentieth century using only one species may have had little success. The results of this work emphasize the fact that in urban reforestation programs the City of São Paulo must consider the environmental and biogeographic characteristics of the species employed and use high levels of biodiversity, since the city lies in a megadiverse biome.

The Application of Geographic Information System in Urban Forest Ecological Compensation and Sustainable Development Evaluation

“…G N represents the annual absorption of nitrogen oxides by the evaluated forest, and K N represents the cost of fluoride treatment. The calculation for the value of dust retention is shown in Equation (10) [34].…”

“…U z = U TSP + U PM10 + U PM2.5 (10) In Equation (10), U TSP represents the value of the annual overdue TSP of the evaluated forest stand. U PM10 represents the value of annual late payment PM10 in the assessed forest stand.…”

“…The study showed that the chemical composition of nitrogen deposition also shifted between the urban, suburban, and rural gradient, and the influence weight of nitrogen deposition on urban forests was higher (0.638). Maur í cio L F et al compared nutrient cycling and litter decomposition between mixed litter and single-species litter (i.e., eucalyptus) to understand the significance of using eucalyptus trees in urban parks [10]. Research has shown that in the urban forests of São Paulo, mixed litter exhibited a greater dry mass loss and nutrient cycling.…”

Sustainable urban systems: from landscape to ecological processes

“…Leveau ( 2021 ) found that environmental filtering by urbanization led to phylogenetical randomness and functional clustering of bird communities in urban habitats. By comparing nutrient cycling and litter decomposition between the litter of a single species and a mixed composition of litter in urban parks in São Paulo City, Brazil, Ferreira et al ( 2021 ) found that both environmental and biogeographic characteristics of the species shall be considered in urban reforestation programs. Additionally, Liu et al ( 2021 ) found that spatial processes and environmental filtering equally contributed to macroinvertebrate metacommunity dynamics in the highly urbanized subtropical river networks in Shenzhen, South China through examining ecological factors and the seasonal difference in structuring macroinvertebrates metacommunity.…”

Multipurpose plants in home gardens of Guarulhos (São Paulo State, Brazil): from biodiversity conservation to public health

“…As the urbanization process increases in cities, the exploitation of natural resources, the alteration of ecological patterns and processes and the reduction of green areas have become an important focus of study (Ferreira et al, 2021;Pereira et al, 2022;Ramon et al, 2022). Urban green areas accomplish important functions such as oxygen production, adjusting the microclimate, and absorbing pollutants, in addition to its landscape function (Silva & Vargas, 2010).…”