The vascular plant species richness of upland urban forest patches in St. Paul and Minneapolis, Minnesota, was found to be positively related to their size. There was no significant relationship between species richness and the distance of these patches to other patches. Mowing and trampling reduced species richness of patches, whereas planting increased richness. Landscape richness can be maintained at a relatively high level by leaving even small unmown forested patches within a more disturbed matrix. However, maximizing landscape diversity would require leaving large forest stands unmown. It is suggested that cultivation be deliberately used as a mechanism for increasing native species richness in urban forests.

Differential profiles are used to describe a pattern of vegetation change across the boundary between annual grassland and coastal sage scrub in southern California. Several techniques for deriving differential profiles are compared; profiles derived from multivariate ordination are found to be most informative. Quantitative description of the vegetation boundaries by differential profiles permitted their classification into two categories of abrupt boundaries and three categories of gradual transitions. Differences between these boundary types appear to be the result of differences in soil texture and compaction, degree of disturbance, and spatial distribution of disturbance.

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