Edge effect and phenology in Erythroxylum tortuosum (Erythroxylaceae), a typical plant of the Brazilian Cerrado

Abstract

The edge of a forest fragment can be considered a zone of transition between the interior of the fragment and the surrounding habitat matrix. Plants along the edge are more exposed to disturbance and microclimate variation than interior plants, resulting in the so-called edge effect. In this study, we compared leaf area, fluctuating asymmetry and chemical (water, nitrogen and tannins) leaf traits between Erythroxylum tortuosum plants inhabiting the edge with those growing in the interior of a cerrado fragment in Brazil. We also describe the temporal variation in the vegetative and reproductive phenological events of E. tortuosum plants throughout the season. Nitrogen, leaf area and fluctuating asymmetry did not differ between the two plant groups. Young leaves of the edge plants had significantly higher levels of tannins and lower levels of water than those of interior plants. We suggest that differences in leaf chemical concentrations between edge and interior plants may occur due to factors such as light intensity, wind, temperature and leaf age rather than plant stress. With respect to plant phenology, most reproductive events occurred during the spring. Leaf buds and young leaves prevailed during the rainy season. In the dry season, however, the vegetative events decreased due to leaf senescence followed by leaf abscission.Keywords: Cerrado, forest fragmentation, physical and chemical leaf traits, plant phenology, plant stress. Efeito de borda e fenologia em Erythroxylum tortuosum Mart. (Erythroxylaceae), uma planta típica do Cerrado brasileiro ResumoA borda de um fragmento florestal pode ser considerada uma zona de transição entre o interior do fragmento e a matriz de habitat. As plantas localizadas na borda estão mais expostas a distúrbios e variações microclimáticas do que as plantas do interior, resultando no chamado efeito de borda. Neste estudo, a área foliar, a assimetria flutuante e os caracteres químicos das folhas (água, nitrogênio e taninos) foram comparados entre plantas de Erythroxylum tortuosum situadas na borda e no interior de um fragmento de cerrado brasileiro. A variação temporal de eventos fenológicos vegetativos e reprodutivos de E. tortuosum também foi investigada durante o período de estudo. Nitrogênio, área foliar e assimetria flutuante não diferiram entre os dois grupos de plantas. As folhas jovens das plantas localizadas na borda apresentaram, significativamente, níveis mais altos de taninos e menores níveis de água do que as plantas do interior. Sugere-se que as diferenças nos conteúdos químicos foliares entre as plantas da borda e do interior devem ter ocorrido em razão de fatores como intensidade luminosa, vento, temperatura e idade foliar e não por causa do nível de estresse da planta. Com relação à fenologia, a maioria dos eventos reprodutivos ocorreu durante a primavera. Os botões foliares e as folhas novas prevaleceram durante a estação chuvosa. No entanto, na estação seca, os eventos vegetativos decresceram por causa da senescência das folhas, seguida pela abscisão fo...

Not all in the same boat: trends and mechanisms in herbivory responses to forest fragmentation differ among insect guilds

“…A positive response to edge conditions might also contribute to compensate (in smaller, edge dominated fragments) for negative effects of habitat loss on the plant population. As predicted, higher water and lower carbon content were found on leaves from interior habitats in comparison with those from edges, which might be attributed to increased sunlight, wind speed and evapotranspiration at the edge (Ishino et al 2012). Moreover, nitrogen content in C. lachnostachyus leaves was higher in edge habitats, probably due to high photosynthetic levels accompanying increased light incidence (Roberts and Paul 2006).…”

“…Such changes in insect herbivory rates could be related to altered resource availability or quality, since habitat fragmentation has been shown to affect plant density (Lienert and Fischer 2003;Valdivia 2011) and leaf traits (Silva and Simonetti 2009;Ishino et al 2012). Furthermore, changes in herbivore populations (Savilaakso et al 2009;Haynes and Crist 2009) or changes in the control of herbivore populations exerted by their natural enemies (Kruess and Tscharntke 1994;De La Vega et al 2012) may lead to altered insect herbivory in fragmented habitats.…”

“…For example, plants in small fragments may have smaller, thicker leaves with lower nitrogen content than plants in continuous forests (Repetto-Giavelli and Cavieres 2007;Silva and Simonetti 2009), whereas plants growing at the forest edge may have lower water content and higher concentration of carbon-based secondary compounds than plants in the interior (Ishino et al 2012). These changes could impact on leaf palatability, reducing levels of insect herbivory.…”

Edge and herbivory effects on leaf litter decomposability in a subtropical dry forest

“…Didham 1998;Riutta et al 2012), but few have addressed leaf litter quality as a potential mechanism mediating edge effects (Vasconcelos and Laurance 2005; Romero-Torres and Varela Ramirez 2011). Indeed, edge microclimatic conditions can alter physical and chemical leaf attributes (Ishino et al 2012). For example, higher radiation from the sun increases leaf carbon content and the carbon: nitrogen (C:N) ratio (Henriksson et al 2003;Muth et al 2008).…”

The importance of remnant native vegetation of Amazonian submontane forest for the conservation of lizards

“…Forest fragmentation leads to the increase of forest edge in relation to forest core and it might have harsh consequences for most animals and plants (Fagan et al, 1999;Laurance and Yensen, 1991), changing their distribution, behaviour, and survival, due to habitat loss (Barbosa and Marquet, 2002;Murcia, 1995;Sartorius et al, 1999;Ishino et al, 2012). Such consequences may be evident up to 500m inside a forest fragment (Laurance, 1991;, but most of these effects are more obvious in the first 35m (Rodrigues, 1998) to 60m (Lovejoy et al, 1986).…”