Long-term passive restoration of severely degraded drylands - divergent impacts on soil and vegetation: An Israeli case study

Land degradation affects extensive drylands around the world. Due to long-term misuse, the Israeli Sde Zin dryland site has faced severe degradation. The study objective was to assess the feasibility of passive restoration in recovering the site. The study was conducted in four land-units along a preservation-degradation continuum: (1) an area that has not faced anthropogenic disturbances (Ecological land); (2) an area that was proclaimed as a national park in the 1970s (Rehabilitation); (3) an area that was prone, until recently, to moderate anthropogenic pressures (Triangle); and (4) a dirt road that was subjected to long-term off-road traffic (Dirtroad). Soil was sampled and analyzed for its properties. The soil physical quality followed the trend of Ecological land > Rehabilitation > Triangle > Dirtroad. Specifically, high soil salinity in the latter three land-units is attributed to long-term erosional processes that exposed the underlying salic horizons. Herbaceous and shrubby vegetation cover was also monitored. The herbaceous vegetation cover followed the trend of Ecological land (86.4%) > Rehabilitation (40.3%) > Triangle (26.2%) > Dirtroad (2.1%), while the shrubby cover was 2.8% in the Ecological land-unit, and practically zero in the other land-units. It seems that despite the effectiveness of passive restoration in recovering the soil's physical properties, the recovery of vegetation is limited by the severe soil salinity.