Morphometric differences of Microgramma squamulosa (Kaulf.) de la Sota (Polypodiaceae) leaves in environments with distinct atmospheric air quality

Abstract

Plants growing in environments with different atmospheric conditions may present changes in the morphometric parameters of their leaves. Microgramma squamulosa (Kaulf.) de la Sota is a neotropical epiphytic fern found in impacted environments. The aims of this study were to quantitatively compare structural characteristics of leaves in areas with different air quality conditions, and to identify morphometric parameters that are potential indicators of the effects of pollution on these plants. Fertile and sterile leaves growing on isolated trees were collected from an urban (Estância Velha) and a rural (Novo Hamburgo) environment, in Rio Grande do Sul, Brazil. For each leaf type, macroscopic and microscopic analyses were performed on 192 samples collected in each environment. The sterile and fertile leaves showed significantly greater thickness of the midrib and greater vascular bundle and leaf blade areas in the rural environment, which is characterized by less air pollution. The thickness of the hypodermis and the stomatal density of the fertile leaves were greater in the urban area, which is characterized by more air pollution. Based on the fact that significant changes were found in the parameters of both types of leaves, which could possibly be related to air pollutants, M. squamulosa may be a potential bioindicator.

Natural radionuclides in lichens, mosses and ferns in a thermal power plant and in an adjacent coal mine area in southern Brazil

“…However, these organisms generally do not have vascular and root systems to uptake elements from the soil and like the lichens they are strongly dependent of the material deposited through wet and dry deposition. As a result, mosses can also act as efficient air pollution indicators because they absorb chemical particles directly from the atmosphere (Elias et al, 2006) mainly in the leaf, which is the part of the plant that shows the greatest response to environmental variations (Rocha et al, 2014).…”

“…Microgramma squamulosa (Kaulf.) de la Sota can be found in trees of primary and secondary forests and in isolated trees in urban and rural environments (Rocha et al, 2014). This native species is considered a potential bio-indicator, since some morphological adaptations were found in it in polluted environments, like a decrease in the stomata area to minimize the pollutants uptake by the plant (Alves et al, 2001).…”

“…This native species is considered a potential bio-indicator, since some morphological adaptations were found in it in polluted environments, like a decrease in the stomata area to minimize the pollutants uptake by the plant (Alves et al, 2001). Rocha et al (2014) suggested that controlled studies involving active exposure to pollutants may contribute to increase the knowledge about Microgramma squamulosa (Kaulf.) de la Sota as a potential bioindicator of atmospheric air pollution.…”

Genotoxicidade do Ar Atmosférico e Epífitos Vasculares em uma Unidade de Conservação de uma Região Metropolitana no Sul do Brasil

“…Especificamente, M. vaccinifolia pode ter assumido os maiores valores de importância devido ao seu potencial alelopático (Peres et al, 2009) e M. squamulosa (Kaulf.) de la Sota possui folhas com elevado índice de esclerofilia (Rocha et al, 2013), densidade estomática e com maior espessura da hipoderme em ambientes com maior grau de poluição (Rocha et al, 2014), sendo essas adaptações importantes frente ao estresse hídrico (Fahn e Cutler, 1992).…”

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“…Specifically, M. vaccinifolia could have taken the highest IVs due to its aleopathic potential (Peres et al 2009) and this species is cyanogenic, what can be reducing the predation (Santos et al, 2005) and increase its population. Microgramma squamulosa has a high sclerophylly index (Rocha et al, 2013), stomatal density and higher thickness of hypoderm in more polluted environments (Rocha et al, 2014), and these adaptations are important under water stress (Fahn and Cutler, 1992). Pleopeltis pleopeltifolia, on the other hand, reduces its exposed leaf surface, thus lessening the damage caused by the solar incidence and the lack of humidity in the environment, a strategy known as poikilohydry (Benzing, 1990), in which it can live with only 25% of its water content over long periods (Moran, 2012).…”