Effects of grazing control on ecosystem recovery, biological productivity gains, and soil carbon sequestration in long‐term degraded loess farmlands in the Northern Negev, Israel

Abstract

AbstractHigh rainfall variability in drylands complicates comparison in time of productivity and soil fertility, and their changes due to altered management. In order to determine the extent, kinetics, and mechanisms of soil and ecosystem recovery achievable in degraded loess plots in southern Israel, aboveground net primary production (ANPP) and soil quality in three fenced plots were analyzed between 2011 and 2017 for experimental confirmation of previously formulated hypotheses on the ecosystem recovery potential in this area. A degraded control plot [<20% biological productivity, marginal plant biodiversity, 50% reduced soil organic matter (SOM)] was analyzed in the same way to normalize annual growth rates in the protected plots. An abandoned ruminants' enclosure was chosen as a reference plot for maximum achievable values to estimate the duration to full ecosystem recovery. The protected loess areas displayed rapid full recovery of soil moisture measured at the end of the rainy season after 3 years already. Annual normalized ANPP increased 5‐fold within 6 years of protection to 3 Mg dry matter per hectare and year, or 60% of the locally achievable maximum ANPP. Herbaceous species numbers increased about 10‐fold in the protected plots as compared to the degraded control plot. Normalized soil carbon sequestration rates of ~5 Mg CO2eq ha−1 yr−1 were deduced from yearly normalized SOM changes. This methodology can be applied universally to determine the true biological production potentials of areas of unknown land degradation/rehabilitation state, and for assessing gains in ecosystem services achievable by restoration of degraded dry agroecosystems such as biodiversity, fodder production, and carbon sequestration.