Conservation management that is focused on the scale of individual habitat patches rarely considers the implications for conservation of metacommunities at the regional scale. Here we examine the conservation implications of long-term changes identified in a vascular plant metacommunity associated with lowland heathland in Dorset, UK. This was achieved by re-surveying 150 patches that were first surveyed in the 1930s and assessing changes in species distributions, diversity, community composition and metacommunity structure. Results were compared for two sets: (i) all remaining heathland patches and (ii) intact heaths, excluding partly degraded sites. Overall, patterns of change were similar for the two sets. Values of γ- and α-diversity both decreased over time as individual patches shifted towards either woodland or improved grassland communities. However, only the intact heaths set exhibited a significant decrease in β-diversity. Both sets lost metacommunity structure over time, suggesting a change in underlying processes. These changes were attributable both to management regimes adopted at local sites, relating to their differing ownership, and to wider processes of environmental change. These results highlight the need to place site-based conservation actions in the context of regional-scale processes, to ensure the long-term conservation of metacommunity structure and function.