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P. Matos et al. 2010. Can lichen functional diversity be a good indicator of macroclimatic conditions
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was also calculated considering functional-groups, by dividing species according to humidity
requirements considering species maximum classification in an available index (Nimis and
Martellos 2008). Therefore, species classified in the index with 1-2 were considered
hygrophytes (LDVhygro), species classified with 3 were considered mesophytes (LDVmeso)
and species classified with 4-5 xerophytes (LDVxero). Because we were dealing with different
ecosystems the LDV values were used as relative values, i.e. the contribution (%) of each
functional group to the total LDV.
2.3 Climatic data and statistical analysis
Lichen data was related with annual average values of macroclimatic series, available from
Atlas do Ambiente (IA 2010). The variables selected were: precipitation (mm, 1931-1960);
temperatre (ºC, 1931-1960); solar radiation (kcal/cm 2 , 1938-1970); real evapotranspiration (mm,
1938-1970); insolation (h, 1931-1960); relative air humidity (%, 1931-1960). Values for each
sampled site were estimated from the available maps. Correlations between lichen variables and
climatic variables were performed using Spearman rank order correlations considering the 149
samples together.
3. Results
No correlation was found between the number of lichen species of each site and the long-term
macroclimatic variables studied, except for relative air humidity (Table 2). However the total
LDV value showed to be positively related not only with relative air humidity but also with
insolation and solar radiation (Table 2).
All the lichen functional diversity variables showed to be related with the long-term
macroclimatic parameters studied, except the percentage of mesophytic LDV with temperature
and relative air humidity (Table 2). The relative value of hygrophytic LDV was positively
related with precipitation and real evapotranspiration, and negatively related with insolation
(Figure 2). On the contrary, the relative value of xerophytic LDV showed to decrease with
increasing precipitation and evapotranspiration, but was promoted by the increase in insolation
(Figure 2).
4. Discussion
The results show that lichen functional-groups can be used as ecological indicators of the
macroclimatic conditions in a regional area. We found that indicators based on lichen functional
groups responded better to changes in macroclimatic conditions, than the total number of lichen
species or its abundance (LDV). The fact that functional diversity responded more clearly to
environmental gradients than total diversity was also found in other works but, for other
environmental stresses, such as ammonia or atmospheric pollution (Pinho et al. 2008b; Pinho et
al. 2009).
The most important climatic factor driving the total richness and abundance (LDV) of lichens
was the relative humidity. However, its abundance was also promoted by higher insolation.
Although only some works (Heylen et al. 2005) showed this relation between species richness
and relative air humidity, the poikylohydric nature of these organisms justifies the importance
of this climatic factor. On the other hand, abundance was also related with insolation. Lichens
need water to be physiologically active and they need light to photosynthesize. In this way, sites
with higher relative air humidity and with a higher number of hours with sun will promote
lichens activity and productivity, and ultimately lichens abundance. This hypothesis was also
raised in a work in a tropical lowland rain forest. Zotz and Winter (1994) suggested that the low
abundance of macroclichens found there was mainly due to low light conditions, combined with
high temperature.
Forest Landscapes and Global Change-New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.