Development of macrophytic vegetation in the Agmon Wetland of Israel by spontaneous colonization and reintroduction

Abstract

The draining of the Lake Hula and swamps, northern Israel, during the late 1950s resulted in the loss of a very diverse and rare ecosystem. Oxidation of the peat soil resulted in ground surface subsidence, while heavy autumn winds have eroded the dry peat. Moreover, agriculture on the peat soils is restricted, because of a nitrate surplus. Predictions that the sinking would continue and that more areas would go out of agricultural production led authorities to re-flood a portion of the Hula Valley in 1994. The aim of the present study was to monitor the spontaneous establishment of vegetation in the re-flooded area, the Agmon wetlands, and to reestablish some of the major plant species lost from the valley when Lake Hula was drained. Within the first two years, 74 plant species colonized the wetland spontaneously. Five out of 11 species designated for reintroduction were successfully established. Cyperus papyrus and Cynodon dactylon demonstrated sustainable potential for lake-shore stabilization. Cyperus papyrus was reintroduced from seedlings and rapidly became the dominant riparian species, while Cynodon dactylon established spontaneously. Re-introduced Nymphaea alba clones were established only in enclosures protected from grazing by the semi-aquatic mammal Myocastor coypu. Nuphar lutea and Iris pseudacorus showed better resistance to grazing. These results demonstrate a high potential for successful re-establishment of much of the original Hula swamp macrophytic vegetation by either spontaneous colonization by extant species from the surrounding areas or by introduction of locally extinct species. As such, there is a good chance that the associated faunal components of the former Lake Hula and swamps that have returned to the region since the Hula rehabilitation project commenced will continue to flourish.