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

Abstract

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 (SO₄ ²⁻) concentrations of 66.67 ± 4.00 mg/L. We identified the existence of SO₄ ²⁻, nitrate (NO₃ ⁻), and ammonium (NH₄ ⁺) 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 SO₄ ²⁻. After two key events that affected levels of SO₄ ²⁻ in the HNR, C. papyrus coverage was altered by more than 80%.

Keywords:

• Altered wetlands
• semiarid wetlands
• peat water
• nutrient gradient
• Cyperus papyrus

Acknowledgments

We would like to thank the Fulbright Program for helping with basic funding in its mission to foster cross-cultural educational exchange and understanding. Sincerest gratitude is extended to Mrs. Talya Oron (Upper-Galilee Ecologist, Israel Nature and Parks Authority) for her help in obtaining data, expert guidance in traveling through the HNR, and unconditional support for completing this project. Also, a special thanks to Dr. Didi Kaplan (Regional Biologist, Northern District, Israel Nature and Parks Authority), Mr. Avri Kadmon (GIS and Mapping, Jewish National Fund), Dr. Doron Markel (Head of Lake Kinneret Monitoring and Management Dept., Israel Water Commission), and Prof. Avital Gasith (Limnologist, Faculty of Life Sciences, Tel Aviv University).