. Changes in land use, particularly the type of forest management, and their spatial pattern, especially woody plant diversity, were related to each other in an area in the Basque region (Spain). The number and diversity of boundaries between landscape patches is related to the development of the spatial complexity of the landscape, C(s), measured in bits and defined as: C(s) = H(b) H(l), where H(b) is the boundary diversity H(1) the spatial heterogeneity generated by these boundaries. As to the vegetation types, changes in land use over the last 50 yr have resulted in a less diversified and more fragmented landscape, especially on a small scale. Forest plantation has become the predominant land use. The frequency of land use changes is studied regarding its influence on the present levels of woody plant diversity.

Different parameters of diversity and spatial niche amplitude (Pielou, 1975, Pineda et aL, 1981 have been used to describe the spatial organization of mediterranean grasslands in Central Spain. A slope sampled by 480 contiguous 8 X 8 cm quadrats proved to have a homogeneous floristic distribution when it was divided into 160 parts and maximum heterogeneity when divided into 4 sectors. These sectors corresponded to different geomorphological zones of the slope. The complexity of vegetation distribution on the slope was reflected by differences in organization -measured by diversity parameter A = H(P/E)/log a N (number of plots) between the parts obtained by division. The presence of low-entropy species -specialists -and high entropy species -generalists -was related to the different scales of slope organization. The spatial distribution of plants was compared for different successional stages. Multivariate analysis of sampling plots confirmed previously identified organizational characteristics and clarified the nature of transitions between communities of different floristic composition or structure.

Pine plantations are an alternative to marginal agriculture in many countries, and are often presented as an option that improves biodiversity. However, these plantations can have adverse environmental effects if improperly managed. To evaluate the effect of forest management practices on biodiversity, the diversity, species richness, dominance and frequency of understory woody plant species in different forests of the Basque Country (northern Spain) were compared. Plantations of exotic conifers (Pinus radiata [D.] Don) of different ages were compared with deciduous forests of Quercus robur L. and Fagus sylvatica L. The effects of different types and intensities of management were taken into account. The differences observed were mainly conditioned by the intensity of forestry management, although the response varied according to forest type and age. In unmanaged pine plantations, the diversity and species richness of the understory increased rapidly after planting (while dominance decreased), remained stable in the intermediate age range, and reached a maximum in plantations more than 25 years of age. Management practices resulted in decreased understory diversity and species richness, as well as greater dominance. This was more pronounced in younger than in older stands. Moderate management, however, favored a greater diversity of the understory in deciduous forests. The species composition of the plantations and deciduous forests were different, the latter having a wider range of characteristic species. Knowledge of how forestry practices influence biodiversity (in terms of diversity, richness, dominance, and species composition) may allow predictions to be made about the diversity achievable with different management systems.

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