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

The Hula Nature Reserve (HNR) (0.3 km ²) in northern Israel is a semiarid wetland ecosystem within the greater Hula Valley. In the 1950s, approximately 60 km ² 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 Cyperus papyrus. 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%.