Reduction in diversity of aquatic plants in a spanish wetland: The effect of the size of inundated area

Abstract

The effect of subsequent decreases in inundated area on the reduction in diversity of aquatic plants in Las Tablas de Daimiel National Park was examined. This Spanish wetland was declared a national park in 1973 in an attempt to protect it from degradation. However, human actions, such as canalization of superficial waters and extraction of subterranean waters, together with the cumulative effects of successive years of low rainfall, resulted in a marked decline in both surface and groundwater resources during the 1980s and 1990s. Diversity of aquatic plants (number of hydrophyte species, genera and families) and size of inundated area (ha) in 1956, 1975 and 1994 were estimated. The power function model S = CAz (or log S = log C+ z log A) was applied to detect a linear relationship between hydrophyte diversity and inundated area. The number of hydrophyte species, genera, and families decreased with decreasing the size of inundated area; the highest values were estimated in 1956 whereas the lowest values were estimated in 1994. This linear relationship implies that a tenfold decrease in inundated area approximately cuts hydrophyte diversity in half. © 1997, Copyright Taylor & Francis Group, LLC.