Evaluating macrolichens and environmental variables as predictors of the diversity of epiphytic microlichens

Abstract

Abstract:In contrast to the frequently assessed macrolichens, microlichens are rarely considered in biodiversity assessments despite their high species richness. Microlichens require generally a higher species identification effort than macrolichens. Thus, microlichens are more expensive to assess. Here we evaluate if macrolichen richness can be used as an indicator of total and threatened microlichen richness. Furthermore, we tested if different sets of environmental variables (modelled climatic variables, forest structure, altitude, etc.) improve the regression models based on macrolichens only or even replace the macrolichens as predictors. Multiple linear regressions were used to model species richness of microlichens, and Poisson regressions for threatened microlichens.On 237 forest plots (200 m 2 ) distributed randomly across Switzerland, 77 macrolichens and 219 microlichens occurred. Macrolichen richness was positively related to the richness of microlichens (R 2 adj. =0·27) and, in combination with threatened macrolichens as an additional predictor, also to the number of threatened microlichens (R 2 dev. =0·14). Environmental variables alone and in different combinations explained between 0·20 and 0·41 (R 2 adj. ) of the total variation of microlichen richness, and between 0·09 and 0·29 (R 2 dev. ) of the total variation of threatened microlichen richness. All models based on environmental variables were considerably improved when macrolichens were included. Furthermore, macrolichen richness turned out to be the most important variable in explaining species richness of all, as well as threatened microlichens. The best models for total microlichen richness reached a R 2 adj. of 0·56. Threatened microlichens were more difficult to model with the best model reaching a R 2 dev. of 0·29. We conclude that in biodiversity assessments with scarce resources, lichen sampling could be focused on the better known macrolichens, at least in many temperate lowland and mountain forests. In combination with environmental variables, reliable predictions of microlichen richness can be expected. If the focus is on threatened microlichens, however, models were not reliable and specialized taxonomists are necessary to assess these species in the field.

Tracking global change using lichen diversity: towards a global‐scale ecological indicator

“…These advantages can be weighted against extra costs incurred for field observer training and laboratory identification of the microlichens (Bergamini et al . ). These two different sets of the community sampled with each method, also related with different strengths to precipitation and relative humidity, despite the almost overlapping sites scores.…”

High‐resolution remote sensing data improves models of species richness

“…Moreover, species richness of epiphytic lichens and woody species are often correlated (Barkman ; Bergamini et al. ; Thor et al. ).…”

Bryophyte and macrolichen diversity show contrasting elevation relationships and are negatively affected by disturbances in laurel forests of Madeira island

“…Bryophyte and macrolichen richness per plot is quite high (as we only sampled 4 m 2 of forest floor and 0.64 m 2 of bark surface) compared with other regions (for lichens: Boch, Prati et al., ; Cleavitt, Clyne, & Fahey, ; Nascimbene & Marini, ; for bryophytes: Horvat, Heras, García‐Mijangos, & Biurrun, and Müller et al., ). We did not sample crustose lichen species, but as their richness is often much higher than that of macrolichens and both diversities are positively correlated (Bergamini, Stofer, Bolliger, & Scheidegger, ), we assume that the total lichen richness per plot also would exceed average values of most parts of other European countries. This and the occurrence of many endemic bryophytes highlights the outstanding conservational value of the laurel forest of Madeira as diversity hotspot of bryophytes and lichens.…”