Indicators in the study sites

Table of Contents

1. Compilers and contributors
2. Introduction
3. Climate indicators
4. Water indicators
5. Soil indicators
   1. Soil drainage
   2. Parent material
   3. Rock fragments
   4. Slope aspect
   5. Slope gradient
   6. Soil depth
   7. Soil texture
   8. Water storage capacity
   9. Exposure of rock outcrops
   10. Organic matter in surface horizons
   11. Degree of soil erosion
   12. Electrical conductivity
6. Vegetation indicators
7. Water runoff indicators
8. Forest fires indicators
9. Agriculture indicators
10. Cultivation indicators
11. Animal husbandry indicators
12. Land management indicators
13. Land use indicators
14. Water use indicators
15. Tourism indicators
16. Human characteristics indicators
17. Institutional indicators
18. Conclusions
19. References

Water storage capacity

Soil water storage capacity corresponds to the amount of water that can be stored into the soil. It refers to the amount of water that is available for the plant growth. If such water content becomes too low, plants will become stressed. The plant available moisture storage capacity of a soil provides a buffer, which determines the plant's capacity to withstand dry conditions. The terms field capacity, and wilting point are used here. Field capacity refers to the soil situation when excess water has drained out due to gravitational pull. Permanent wilting point refers to the soil situation when a plant wilts beyond recovery due to a lack of water in the soil. Available water in this project was considered as the amount of the water held in a soil between field capacity and permanent wilting point. The following classes of soil water storage capacity (SWSC) have been defined: (a) SWSC<50 mm, (b) SWSC=50-100 mm, (c) SWSC=100-200 mm, (d) SWSC=200-300 mm, and (e) SWSC>300 mm.

Table 3 shows soil water storage capacity that has been determined for 1309 field sites, corresponding to 13 study sites. Fig. 26 shows the majority of the study field sites that had very low (<50 mm) and low (50-100 mm) SWSC indicating high vulnerability to desertification under semi-arid and dry sub-humid climatic conditions, covering 23.1% and 25.1% (Fig. 26) of the study field sites, respectively. Such fields sites were found in some cases in all study sites but all the study field sites of Secano Interior-Chile, Mamora Sehoul-Morocco, and Santiago Island-Cape Verde had only these two classes of SWSC. Moderate SWSC values were found in 21.3% of the study field sites located mainly in all the study sites except those mentioned above with low SWSC. High (200-300 mm) and very high (>300 mm) SWSC classes cover 19.6% and 10.8% of the study field sites, respectively. Such classes of SWSC were measured in all study field sites except for Eskisehir-Turkey, Mamora Sehoul-Morocco, Secano Interior-Chile, and Nestos Basin Maggana-Greece.

Fig. 26. Distribution of soil water storage capacity classes measured in the study field sites