Rehabilitating degraded drylands by creating woodland islets: Assessing long-term effects on aboveground productivity and soil fertility

• We assessed woodland islets effects on biomass and soil fertility in drylands.
• Field and remote sensing data were combined for long-term monitoring.
• Soil quality, biomass and rain use efficiency were significantly improved.
• RUE remained constantly higher in planted site despite of a rainfall decline.
• Woodland islets were more efficient than afforestation in improving productivity.

We evaluated the effects of Acacia victoriae islets planted in 1993 in the Negev drylands on the productivity of the native herbaceous vegetation and soil fertility. Biomass, mineral-P, N and K and soil organic matter were measured from the planted and an adjacent unplanted area. The satellite-derived Normalized Difference Vegetation Index (NDVI) from MODIS was used to expand the timespan of the analysis after calibration with field data. Results showed an average improvement in biomass and rain use efficiency (RUE) of 40% compared to the unplanted area. Improvement was also observed in all nutrients concentrations and organic matter. Biomass was highly related to precipitation (R2 = 0.90, p < 0.001), gradually declining from 2001 to 2009. Although declining with precipitation, RUE was maintained constantly higher in the planted area with respect to the unplanted lands even in dry years. The total biomass gained since plantation was estimated at 60 g m−2 yr−1 (i.e. 12 t ha−1) for a 20-year period. Our results suggest that planting woodland islets may significantly improve soil quality and biomass productivity of the native vegetation in drylands in a relatively short time.