SPATIAL AND SHORT-TERM TEMPORAL VARIATIONS IN RUNOFF, SOIL AGGREGATION AND OTHER SOIL PROPERTIES ALONG A MEDITERRANEAN CLIMATOLOGICAL GRADIENT

Physical and chemical soil properties were measured along a mountainou s climatological gradient in the province of Alicante (Spain). The obj ective was to evaluate how the climate affects certain soil properties at different temporal and spatial scales. These properties include in filtration, runoff and sediment concentrations resulting from rainfall simulation experiments performed in winter and in summer. Chemical so il properties like carbonate content, organic matter content and CEC w ere analysed in reference soil profiles along the gradient. Physical s oil properties like soil moisture content, macroaggregation and waters table microaggregation were measured at monthly intervals during a yea r. The comparison of the results was done at different spatial (site, slope and patch) and temporal (monthly and seasonal) scales by means o f some statistical tests. It can be concluded that there are some soil properties positively related to the gradient, like organic matter, c lay content and CEC which increase with the annual rainfall. However, runoff coefficients and erosion are higher when the climatic annual ra infall. However, runoff coefficients and erosion are higher when the c limatic conditions become more arid. Aggregation and infiltration capa city are higher on north-facing slopes and in vegetated patches than i n south-facing slopes and in bare patches. (C) 1998 Elsevier Science B .V. All rights reserved.