In which biome is the most degradation happening? The case of croplands, rangelands, forests, and irrigation water in Tunisia

This study estimated the quantities and monetary values of ecosystem services (ESS) lost due to in/inadequate action to control agricultural resource degradation in Tunisia. We used a combination of GIS, remote sensing, and data from publications and official statistics to generate estimates of total and percentage of crop lands, rangelands, and forests falling in one of three (low, moderate, and severe) degradation classes and the corresponding biomass yield (ton/ha). We used a combination of market and non-market valuation methods to estimate the value of ESS lost due to inaction. The estimates are provided for each biome x province combination. Using extremely conservative assumptions, we estimated that in/inadequate action is causing Tunisia to lose at least 1.97 million tons of potential production of different food crops, 209 thousand tons of forest biomass, and 2.5 million tons of forage from rangelands, and at least 736 million cubic meters of irrigation water annually. In addition, Tunisia is losing at least 141.68 million tons of soil which is also associated with the release of at least 779 thousand tons of carbon into the atmosphere. Rangelands constitute 73.51% of the total national soil erosion out of which 67.7% is happening in the five Southern provinces where erosion rates as high as 52t/ha are recorded. The monetary value of all the ecosystem services that Tunisia is losing annually in all biomes is estimated to be at least $2.17 billion (4.65% of GDP). The main cost of in/inadequate action in the country in monetary terms is related to crop lands which constitute 53.98% of this loss followed by irrigation water, and rangelands which contribute 28.19% and 12.09% of total cost of inaction, respectively. These estimates have generated much discussion among high officials in Tunisia on the need to solicit funds to control land degradation, especially in rangelands.