Vegetation and soil analysis of topo-sequences in the Orinoco Llanos

Mauritia flexuosa palm swamp communities: natural or human-made? A palynological study of the Gran Sabana region (northern South America) within a neotropical context

“…In the Orinoco delta and the Amazon estuary, M. flexuosa forms dense and extensive communities flooded by freshwaters reaching, but not crossing, the tidal boundary (Huber, 1995c;White et al, 2002;Vegas-Vilarrúbia et al, 2007). In more open landscapes, as for example the Orinoco savannas (including the Gran Sabana) and the Brazilian "cerrados", these palm swamps occur chiefly along water courses and in lake shores, preferably on permanently or seasonally flooded soils (González, 1987;Montes & San José, 1995;Ratter et al, 1997;Sampaio, 2011). In spite of the biogeographical, ecological and economical importance of M. flexuosa palm swamps, detailed studies on their composition are rare .…”

Seasonal inundation patterns in two large savanna floodplains of South America: the Llanos de Moxos (Bolivia) and the Llanos del Orinoco (Venezuela and Colombia)

“…In this study, however, we define the Llanos del Orinoco as the lower lying savanna areas that are subject to seasonal inundation. We exclude the more upland savannas to the east because most of that region is not contiguous floodplain and bears a closer resemblance to the Cerrado savannas of Brazil (San José and Montes, 1989;Montes and San José, 1995). The floodplains of this region are drained by two major tributaries of the Orinoco River, both of which originate in the Andes: the Apure River (mean annual discharge, 2300 m 3 /s) and the Meta River 5600 m 3 /s (Lewis et al, 1995).…”

Heterogeneity of the inland water–land palm ecotones (morichals) in the Orinoco lowlands, South America

“…1) (Pérez 1981;San José et al 2001). These conditions lead to the presence of the inland water-land palm ecotones (i.e., Morichals) (Pérez 1981;Montes and San José 1995;San José et al 2001). The ecotone soils involve Entisols and Histosols (Gonzalez 1987;Montes and San José 1995) with high soil aluminum saturation, which reaches up to 90% and deficiencies in K, Ca, Mg, and P (Mazorra et al 1987).…”

“…Understanding community features in ecotones could be crucial for delineating community heterogeneity at different scales. In this sense, there is a vast pattern of ecotones ranging from open water-dominated vegetation to those where available water is controlled by vegetation (Montes and San José 1995). Accurate estimates are required for the study of a variety of ecological, hydrological, and climatic conditions, yet are difficult to obtain.…”

“…The Orinoco lowlands (0.4 9 10 12 m 2 ) of northern South America are extensively covered by ecotones, which are connecting aquatic and land phases in vegetational toposequences (Montes and San José 1995). These areas provide an opportunity to study a wide range of inland water-land ecotones.…”