Corticolous lichen species as indicators of disturbed/undisturbed vegetation types in the central mountains of Sri Lanka

Corticolous lichens in the central mountains of Sri Lanka differ with vegetation type, disturbance and climate. All growth forms of lichens were studied in 42 plots (six plots x seven vegetation types), yielding 124 species. Lichen species diversity varied with number of tree species per plot (correlations) and differed with disturbance group, vegetation type and climate zone (general linear models). Lichen community composition (estimated cover of 74 species each at >= 3 plots) varied along two ordination gradients secondarily correlated with disturbance (nonmetric multidimensional scaling, NMS). Undisturbed and disturbed plots (mostly grouped by vegetation type) were divided along NMS axis 1, correlating with distance to undisturbed forest. Longest-disturbed plots differed from all others along NMS axis 2 and were correlated with canopy cover. Climate was weakly reflected on the ordination as the proximity of two plot clusters in montane vegetation types. Indicator species analyses (ISA) of lichen cover by plot identified 60 strong indicator species (indicator value >= 50%,P < 0.015). Fifty-seven species were indicators for individual vegetation types (28 of them for undisturbed types); three were for a disturbance group only; 11 were also for a disturbance group or climate zone. Most species strongly driving ordination patterns were also ISA indicators. Most lichens were crustose (39, with 24 in theGraphidaceae). Each vegetation type had at least one indicator with trentepohliod algae (increasing for undisturbed plots) and one with chlorococcoid algae. Two visually distinct indicator species, three genera and two multi-genus groups will be useful to parataxonomists in forest evaluation.