AVAILABLE SOIL WATER CAPACITY AS A DISCRIMINANT FACTOR IN MIXED OAK FOREST OF CENTRAL ITALY

Abstract

Soil water content is a critical factor in Mediterranean forest vegetation, especially in areas subjected to prolonged summer drought where winter and autumn rainfall are the main sources of water. Available soil water capacity (AWC) is the maximum amount of water available for plants that a soil could possibly contain. Each soil has a specific available water capacity, however, most of the published literature on AWC refers 10 agricultural settings, although the interaction between the soil and the vegetation dynamics has long been recognized. The aim of this study was to investigate whether this edaphic factor could be discriminant in species assemblage of communities belonging to the thermophylous oak forest (order Quercetalia pubescentis). Thirty-two vegetation releves and soil profiles were carried out in five different sites, with a similar pluvio-thermic regime, located in the sub-coastal belt of Latium, Central Italy. From the physical\-chemical analyses of soil profiles, the AWC values, of the related releves, were calculated. Multivariate statistical analysis was applied to the vegetation surveys, using Cluster Analysis from which a classification in three different clusters was obtained; subsequently the AWC values were grouped according to the c1assification obtained. Analysis of variance was used to test similarity and the output pointed out a significant difference among the three clusters (F=6.35; P