Lichens as indicators of environmental conditions

Lichens as indicators of environmental conditions

The use of lichens as indicators of `old- growth forest’ with long term ecological stability was first developed in Britain from extensive surveys of the lichen flora of woods with independent documentary evidence (Rose 1976, 1992). The increasing need for evaluation of sites has led to the development of the New Index of Ecological Continuity where widespread faithful species form the basic indicator list and specialist or regionally rare species are counted as “bonuses” (Rose 1992). Similar techniques have been used to define species of `old-growth’ forests in the USA and Canada, and further developed to assess habitat diversity in managed forests of the Pacific Northwest by arranging species in functional groups (Rosentreter, 1995). This research has been undertaken in areas where the lichen flora is reasonably well known, and in a continuum of management options from a base-line of undisturbed old-growth forests. Lichens have also been used widely as indicators of atmospheric conditions in particular acid rain deposition, where absence of sensitive species and presence of tolerant species has been used to construct a scale of atmospheric pollution (Hawksworth & Rose, 1970).

Lichens as indicators of environmental conditions in tropical forests

Lichens have been used to interpret the effects of fire history in tropical forests of Thailand where the replacement of fire-sensitive evergreen forest by fire-tolerant deciduous dipterocarp forest could be assessed over time using lichen taxa associated with each forest type (Wolseley et al., 1997b). In lowland dipterocarp forests of Peninsular Malaysia and Danum Valley Sabah lichens and bryophyte taxa were assessed in plots within established 50 ha Forest Dynamic Plots, and in a range of logged, regenerating and planted forest conditions. The highest diversity of lichens and bryophytes was found in the 50 hectare plots where no known extraction had occurred, and plots in logged forests where canopy trees were retained showed a higher diversity and retention of sensitive species than that of heavily logged forest (Wolseley et al., 1998a, 1998b).