Isotopic composition (d(13)C and d(15)N) in the soil-plant system of subtropical urban forests

Autor(es)

Pereira, Milton Augusto Goncalves ; Domingos, Marisa ; da Silva, Emerson Alves ; Aragaki, Sonia ; Ramon, Mauro ; de Camargo, Plinio Barbosa ; Ferreira, Mauricio Lamano

• Tipo de documento: Artigo Científico
• Fonte: Science of The Total Environment; v. 851, p. 11-pg., 2022-08-27.

Resumo

This study brings information on the dynamics of C and N in urban forests in a subtropical region. We tested the hypothesis that C and N isotopic sign of leaves and soil and physiological traits of trees would vary from center to periphery in a megacity, considering land uses, intensity of automotive fleet and microclimatic conditions. 800 trees from four fragments were randomly chosen. Soil samples were collected at every 10 cm in trenches up to 1 m depth to analyze C and N contents. Both, plants and soil were assessed for delta C-13, delta N-15, %C and %N. Physiological traits [carbon assimilation (A)], CO2 internal and external pressure ratio (Pi/Pa) and intrinsic water use efficiency iWUE were estimated from 813C and A 813C in leaves and soil ranged from -27.42 %o to -35.39 %o and from -21.22 %o to -28.18 %o, respectively, and did not vary along the areas. Center-periphery gradient was not evidenced by C. Emissions derived from fossil fuel and distinct land uses interfered at different levels in 813C signature. 815N in the canopy and soil varied clearly among urban forests, following center-periphery gradient. Leaf 815N decreased from the nearest forest to the city center to the farthest, ranging from < 3 %o to <-3 %o. 815N was a good indicator of atmo-spheric contamination by NOx emitted by vehicular fleet and a reliable predictor of land use change. %N followed the same trend of 815N either for soils or leaves. Forest fragments located at the edges of the center-periphery gradient presented significantly lower A and Pi/Pa ratio and higher iWUE. These distinct physiological traits were attributed to successional stage and microclimatic conditions. Results suggest that ecosystem processes related to C and N and ecophysiological responses of urban forests vary according to land use and vehicular fleet. (AU)

• Processo FAPESP: 19/24325-2 - Fluxo de carbono e nitrogênio no sistema solo-planta-atmosfera de florestas urbanas da cidade de São Paulo, SP
• Beneficiário: Maurício Lamano Ferreira
• Modalidade de apoio: Auxílio à Pesquisa - Regular