Data from an extensive field survey aiming to test the role of the patch-size distribution of vegetation as a suitable indicator of desertification processes

Data from an extensive field study gathered in 29 semiarid Stipa tenacissima steppes located along an environmental gradient spanning from the center to the south-eastern part of Spain. The data consist of the patch-size distribution of perennial vegetation and of different soil variables used as surrogates of ecosystem functioning (soil respiration, organic carbon, total nitrogen and phosphorus, potassium, pH, water holding capacity and the activity of three enzymes related to the carbon [b-glucosidase], nitrogen [urease] and phosphorus [phosphatase] cycles). The data were gathered to: i) test if transitions from a patch-size distribution characterized by a power law function to another described by a truncated power law function occur in the more degraded sites (i.e., in those sites closer to desertification), and ii) explore how joint changes in this distribution and in total plant cover, the importance of which has often been highlighted in the study of desertification, relate to surrogates of desertification processes