The daily and seasonal variations of water consumption by transpiration and the influence of meteorological parameters on the transpiration intensity were studied in two species of the Fagaceas, Nothofagus obliqua and Notholagus dombeyi.. These species have a wide distribution in Chile and are of- considerable forestry importance. To determine the water consumption of these two species the method proposed by Huber and Ramirez (8) was applied. The experiment was carried out at the meteorological station Isla Tern, of the Austral University of Chile (Valdivia, Chile). The results indicated that increases of solar radiation and air temperature and a decrease of relative humidity lead to an increase in transpiration intensity in both species, which are higher in N. obliqua than in N dombeyi The MatiMUM transpira-don intensities reached were 2 4 1 m 2. in N. obliqua and 1.4 1 in' d" in N dombeyi.. The multiple regression analysis indicated that for both species solar radiation was the most important meteorological factor in regard to transpiration.

Summary The effects of water level fluctuation on the zooplankton community of Lago Grande (Rio Solimões, State of Amazonas, Brazil) were investigated from April, 1979 to March, 1980. Quantitative samples of zooplankton, water depth and Secchi disc transparence were taken at two stations located in the middle of the lake. Highest zooplankton densities were observed during the low water period, and these were correlated with higher nutrient levels. These nutrients appears to come from the surrounding inundation forest and from the substrate of the lake. The effects of high turbidity on the zooplankton community is also discussed, especially in relation to Cladocera. | Resumo Os efeitos da flutuação do nível da água sobre a comunidade zooplanctônica do Lago Grande (Rio Solimões, Brasil) foram investigados no período de abril de 1979 a março de 1980. Amostras quantitativas de zooplâncton e medidas de profundidade do lago e de transparência da água foram tomadas em duas estações localizadas no meio do lago. A maior densidade de zooplâncton foi observada durante a época seca e provavelmente está relacionada com: 1) o material orgânico proveniente da floresta inundada que durante a vazante, entra na região limnética; 2) com o sedimento que se mistura na coluna d'água quando o lago fica muito seco. Os efeitos da alta turbidez sobre a comunidade zooplanctônica são também discutidos especialmente em relação à Cladocera.

11380 | Tesis (Ing Agr) | 76 p.

Ingeniero Agrónomo | Pregrado