Litterfall dynamics in a iron-rich rock outcrop complex in the southeastern portion of the Iron Quadrangle of Brazil

Abstract

Ecosystems on cangas (duricrust) present considerable heterogeneity of habitats due to microtopographic variations, soil accumulation and a variety of plant functional groups. Therefore, spatial and temporal ecosystem processes such as litterfall are to be expected to be large, and the absence of a level of productivity represents all the facets of iron--rich landscapes. We investigated litterfall in a iron-rich rock complex in the Iron Quadrangle of Brazil, with habitats formed on different evolutionary stages of the soil, resulting in a gradient of biomass, canopy cover and community structure. The measurements were made in open field areas, dominated by herb-shrub vegetation and interspersed with islands of dense vegetation in which there were individual trees, as well as in areas of semideciduous forest. The litterfall, especially that of leaf litter, followed the gradient of woody cover and was approximately two times greater in the forest formation. However, the spatial and temporal variations in deposition were greatest in the herb-shrub areas and least in the semideciduous forest area, intermediate values being obtained for the tree island areas. The peaks in litterfall also varied among habitats, occurring in some periods of the rainy season and during the transition from rainy to dry in the herb-shrub and tree island areas, whereas they occurred at the end of the dry season in the semideciduous forest area. The results show significant differences in the patterns of litterfall among different physiognomies within the same iron-rich rock complex, indicating the need for expanded studies, focusing on the flow of matter and energy in such environments.

Foliar water‐uptake strategies are related to leaf water status and gas exchange in plants from a ferruginous rupestrian field

“…This study was carried out in a ferruginous rupestrian field in the Cachoeira das Andorinhas Environmental Protection Area, in the municipality of Ouro Preto, Brazil (20°21′30″S/43°30′11″W). The local ecosystem is characterized by herbs, shrubs, and treelets growing in shallow soils on rock outcrops of itabirites or cangas (Valim et al., ). The area has an average altitude of 1492 m a.s.l., and fog is frequent (Fig.…”

Phanerogamic flora and vegetation of Itacolomi State Park, Minas Gerais, Brazil

“…However, the fog events, common in the studied area, may favor the coexistence of species with different phenological strategies (Valim et al 2013). Thus, care must be taken when generalizing the terminology "seasonal semideciduous forests" (Scolforo et al 2008) for the forest of this park and similar surrounding areas.…”

Strategies of leaf water uptake based on anatomical traits

“…Material and field data collections were carried out in April, August and November 2013 and February 2014 in two phytophysiognomies with nearly the same altitudinal gradient: (i) field formation with canga vegetation outcrops, characterised by herbaceous-shrub vegetation, and (ii) seasonal semideciduous forest formation on cambisols or latosols, characterised by the presence of shrub-arboreal vegetation covered with a thick litter layer (Valim et al 2013).…”

“…; Valim et al . ). A small set of species co‐occurs in both environments, which are in the same climate domain but experience different degrees of water deficit.…”

“…In a rupestrian field in southeastern Brazil, Baeta (unpublished data) estimated that this water source corresponds to about 13% of the annual water volume provided by rain, and to almost 85% of the water uptake in the dry season. Also, as on many other hilltops of the region, the topographic variation creates opportunities for the establishment of a mosaic of vegetation physiognomies, varying from predominantly fields on shallow soils to forests on more developed soils (Jacobi et al 2007;Valim et al 2013). A small set of species co-occurs in both environments, which are in the same climate domain but experience different degrees of water deficit.…”