Responses of tropical and subtropical plants to air pollution

Abstract

The tropical and subtropical regions of the world are facing strong negative effects of globalization, weakening the critical balance between ecosystem stability and socioeconomic development. Apart from increasing pressures of global climate change, deforestation, and shifts in land use pattern, air pollution is emerging as one of the major factors influencing ecosystem structure and function. Issues related to health, agricultural production, and economic losses due to air pollution in the tropical and subtropical regions are well known; however, information on air pollution-related effects on the tropical vegetation is limited. Therefore, based on the current literature, the status of air pollution and its effects on vegetation in the tropical and subtropical regions of the globe are explored in this chapter to understand the current scenario and to identify the knowledge gaps. Spatial and temporal variations were detected among different regions for particulate matter, its constituents, and gaseous pollutants including identification of the factors and sources influencing the air quality. Air pollution impacts were assessed based on changes in ecosystem structure and functions such as the patterns of biodiversity change, alteration in litterfall and decomposition, the response of leaf functional traits, and bioaccumulation in the community or individual plant species. Air pollution significantly influenced major ecological processes such as litterfall, decomposition, and plant diversity indirectly through changes in soil quality as well as through a direct effect on growth and physiol ogy of native plants. Plants respond to changes in air quality through alternation in growth and morphology, physiological plasticity, and modifying leaf functional traits. These responses are both species- and pollutant-specific, as not all species responded equally to air pollution. Bioaccumulation pattern also showed a distinct relationship between pollutant accumulation and species specificity.