Movimento de água subterrânea em ecossistema Campina Amazônica ()

Abstract

Resumo Primeira tentativa para determinar a magnitude do fluxo de água subterrânea, a fim de estimar o potencial de elementos biologicamente importantes no ciclo de nutrientes no ecossistema Campina Amazônica. O fluxo saturado da água, dentro do lençol freático, foi estudado por 2 métodos, no período de dezembro de 1974 a janeiro de 1975: 1) aplicando-se a equação de Darcy; 2) usando-se um traçador 3h (100 mCi) na forma de 3H2O. As variações apresentadas pelos dois métodos foram provenientes da alta permeabilidade do solo arenoso, propiciando rápidas variações do lençol freático, totalmente influenciado pelas precipitações pluviométricas. Ambos os métodos apresentaram resultados da mesma ordem de grandeza, indicando a existência de um movimento horizontal do fluxo saturado da água no lençol freático da Campina, da ordem de 0,0018 cm3. cm-2. h-1.

Dissolved organic matter and terrestrial‐lotic linkages in the Central Amazon Basin of Brazil

“…Neither groundwater nor surface water of the catchment have been studied previously, but Reichardt et al [1975] examined groundwater flow in other Spodosols of the Campina Reserve. Using both tritium and calculations based on Darcy's law, they estimated horizontal flow rates within the saturated zone to be of the order of 6 x 10 -6 crn/s, but this rate varied greatly, increasing by as much as 2 orders of magnitude during precipitation events [Reichardt et al, 1975]. Soil samples were collected using a hand auger.…”

The specialized white-sand flora of the Uatumã Sustainable Development Reserve, central Amazon, Brazil

“…This pronounced dif ference in both species richness and composition (Gentry 1988;Stropp et al 2011) can be explained by the extreme environmental conditions that campinarana experience throughout the year. Thus, nutrient poverty (Tiessen et al 1994;Luizão et al 2007;Mendonça et al 2015), drought during dry months due to high temperatures, low water retention capacity of sandy soils (Coomes 1997;Adeney et al 2016), and the flooding of the root system during wet months (Richardt et al 1975;Franco and Dezzeo 1994;Tharghetta et al 2015) can act as strong environ mental filters selecting specific taxa. These environmen tal filters of campinarana ecosystems are shared by other Amazonian oligotrophic ecosystems (ex: igapó and rest inga), which could help to explain the 29 species con sidered oligotrophic habitats specialist reported in this study.…”

“…The intense leaching of sandy soils reallocates and depos its Fe, Al, Mg, and other compounds in the lower layers of the soil. This process forms a cemented layer (hard pan) that can block water drainage and, thus, during the wet season, excessive rainfall subjects some physiogno mies to the (shallow) flooding or waterlogging of the root system through elevated groundwater levels for months (Richardt et al 1975;Kubitzki 1989;Quesada et al 2011); therefore, many campinaranas are classified as wetlands (Junk et al 2011). In contrast, during the dry season, the low water retention capacity of sandy soils, combined with high temperatures and related high evapotrans piration rates, lead plants to suffer from physiological drought (Franco and Dezzeo 1994).…”

Unveiled diversity: Amazonian Campinaranas harbor twice the number of bryophyte species recorded in the last century

“…Campinaranas are unique vegetation patches in the Amazonian biome, characterized by white-sand soils with relatively low nutrient content subject to periodic flooding coupled with fluctuating groundwater levels (Reichardt et al 1975;Anderson 1981;Adeney et al 2016).…”