Ground vegetation as an indicator of ecological integrity

摘要

Indicators are being sought for monitoring the ecological integrity of forests and other kinds of ecosystems. Bio-nlogical measures are commonly used as indicators because of their inherent ecological importance and ability to provideninsight into environmental change. Such measures are commonly based on data from sets of permanent plots in which thenabundances of plant species are monitored. However, the data may be difficult to interpret, especially if corresponding in-nformation on natural and anthropogenic stressors is lacking. In this review, we examine general principles of indicator usenand discuss the types of plot-based compositional measures obtained from vegetation that may be most relevant for moni-ntoring ecological integrity. Our focus is on the ground vegetation of forested ecosystems, but the principles discussed arenrelevant to other vegetation types. Individual plant species, guilds, aliens, diversity indices, Ellenberg indicator values, thenfloristic quality assessment index, multivariate and multimetric indicators are examined, as well as concepts of thresholdnchanges and the need for reference states. The usefulness of any given approach tends to be highly context specific. In par-nticular, the value of using individual species as indicators is highly dependant on factors such as the character of the floris-ntic community of interest and the types and intensities of anthropogenic stressors. Alien species are considered to benespecially valuable indicators of changes in ecological integrity due to their established relationships with anthropogenicnstressors, known historical state, relevance to all floristic communities, and ability to cause undesirable changes to biodi-nversity and ecological processes.