**7. Vegetation-soil interaction**

The typical soils of arid and semiarid environment are poor in fertility. However, when native vegetation is still present, the properties of soils are positively enhanced. Table 2 shows the behavior of fertility of soils in three different native plant species and at bare surfaces. Organic matter in surface with vegetation cover is improved by 100% beneath canopy of Prosopis and Acacia.


Table 2. Soil characteristics comparing three different plant species of native vegetation.

Soils under trees canopies in semi-arid environments are often more fertile than soils from the surrounding grasslands. Quantities of mineralizable nitrogen, phosphorous, potassium, calcium, organic matter, and the microbial biomass, are significantly higher in soils beneath the canopy than in the open area (Belsky et al., 1989).

Soil characteristics shows are better beneath species vegetation in comparison with bare surface, found up to twice of organic matter, minor values of bulk density, greater values of hydraulic conductivity that foster the increase in infiltration rates (Vásquez-Méndez et al., 2010).
