SPATIAL PATTERN IN ANTHYLLIS CYTISOIDES SHRUBLAND ON ABANDONED LAND IN SOUTHEASTERN SPAIN

Univariate and bivariate distribution patterns of small shrubs on aban doned land in semi-arid southeastern Spain were investigated by second -order spatial analysis (Ripley's K-function). All shrubs (Anthyllis c ytisoides and subdominant Artemisia barrelieri) were either randomly d istributed or clumped at scales of 0.25 - 1.0 m. The pattern shown by A. cytisoides shrubs alone changed from clumped to random with decreas ing density. Pattern analysis and demographic data suggest a successiv e replacement of A. barrelieri, which had high proportions (44 - 86 %) of dead shrubs, by the dominant A. cytisoides. In two of three plots there was a positive association between A. cytisoides and A. barrelie ri at a scale of 0.25 - 0.5 m. In the third plot, believed to represen t a more advanced stage of colonization, there was a negative associat ion (repulsion) between the two species, presumably as a result of int erspecific competition from A. cytisoides. Dead shrubs present in spri ng 1994 were randomly distributed in all plots. Living and dead A. cyt isoides shrubs were positively associated at a scale of 0.5 m, suggest ing that the shrubs died as a result of intraspecific competition in s mall clumps. The shrubland previously dominated by A. barrelieri is ch anging to A. cytisoides shrubland with increasing biomass and ground c over.