Chemical evolution and vegetation response in an altered wetland ecosystem, Hula Valley, Israel (1988-2004)

摘要

The Hula Nature Reserve (HNR) (0.3 km2) in northern Israel is a semiarid wetland ecosystem within the greater Hula Valley. In the 1950s, approximately 60 km2 of wetlands were drained and converted to farmland. The HNR was established during this time to preserve some of the native flora and fauna. Agricultural runoff and a reflooding of the area with peat water in 1999 resulted in high sulfate (SO_4(2-)) concentrations of 66.67 ± 4.00 mg/L. We identified the existence of SO_4~(2-), nitrate (NO_3~-), and ammonium (NH_4~+) nutrient gradients as well as related mechanisms affecting the growth and dieback of Cyperuspapyrus. The observed changes in the C. papyrus populations were caused primarily by fluctuations in SO_4~(2-). After two key events that affected levels of SO_4~(2-) in the HNR, C. papyrus coverage was altered by more than 80%.