Instability in newly-established wetlands? Trajectories of floristic change in the re-flooded Hula peatland, northern Israel

Drainage of the 6,000 ha Hula Lake and peatland in northern Israel in the late 1950s caused the loss of a very diverse and rare ecosystem and an important phytogeographic meeting zone for Holarctic and Palaeotropical species. Draining the Hula peatland was only partially successful in creating a large fertile area for cultivation, and in 1994 this led the authorities to re-flood 100 ha of the valley—the Agamon (Agmon)—with the aim of rehabilitating the diverse wetland landscape, promoting ecotourism and creating a clear-water body that would contribute to the purification of Lake Kinneret. The vegetation of the restored wetland was monitored for ten years (1997–2006), recording the establishment and abundance of vascular plant species. More than 20 emergent, submerged and riparian species became established. Like a number of other shallow-water wetlands, the Agmon is characterised by considerable ecological fluctuations. This has been expressed in prominent floristic changes in the Agamon since it was created. An increased abundance of Ceratophyllum demersum and Najas minor and a decline in Potamogeton spp., Najas delilei and filamentous algae have been observed. A long-term decline in water level and sediment accumulation has brought about a significant rise in the incidence of Phragmites australis, Typha domingensis and Ludwigia stolonifera in the south-eastern area. A GIS analysis of changes in species dominance shows fluctuations over the years, with only a partial trend of succession towards a P. australis, T. domingensis and L. stolonifera community.