Distribución de especies del género "trifolium" l. en campos de cultivo abandonados

Abstract

Species of the genus Trifolium L. vary both qualitatively and quantitatively with the duration of abandonment since tilling. This has led the authors to conduct a study of the successional sequence in grasslands of different áreas of the province of Salamanca (W. Spain). Twenty two species of clover are found in this gradient, with a mean cover valué of 9.4%. Both the mean cover and the number of species increase along succession. The results of correspondence analyses are consistent with the working hypothesis, although the successional gradient is partly overlapped by another one involving soil humidity. The valúes of alpha diversity, gamma diversity and heterogeneity increase along succession and at the same time the environmental conditions diversify and increasingly depart from the homogeneity imposed by continued tilling. The sensitivity of the clover species to the changes inherent in the successional sequence studied is demonstrated, although other subordínate sources of variation also exist and are discussed.