How do forest management and habitat impact the phylogenetic and functional group diversity of lichen communities?

Background/Question/Methods:

Lichens are well-known indicators of environmental health. Using field and molecular sequence data, we assess how forest management strategies and habitat affect the phylogenetic diversity plus morphological and chemical diversity of lichen-forming fungi in Upper Midwest, USA.  Three plots each were sampled of even-aged, uneven-aged, and old growth northern hardwoods (NH) stands, uneven-aged and old growth hemlock-hardwoods (HH) stands. This study is restricted to Parmeliaceae, the most speciose family of lichen-forming fungi, which includes several species widely-used as indicators of environmental health.  

Results/Conclusions:

In NH stands, average species richness per plot declined with management: old growth (15.3); uneven- (11.7); even-aged (10) stands, with little difference for uneven (15) and old growth (15.3) HH stands.  Similar trends were seen from molecular sequence data: old growth NH stands had the greatest amount of phylogenetic diversity (63.6%), even-aged stands had the least (39.8%) and uneven-aged stands were intermediate (53.3%).  Little difference in phylogenetic diversity was seen between uneven-aged (60.5%) and old growth (63.6%) HH stands.  Average species richness and phylogenetic diversity per plot were comparable between old growth stands of both forest types, but uneven-aged HH stands had greater average species richness and phylogenetic diversity than uneven-aged NH stands.  Parmeliaceae lichens were primarily foliose taxa; slightly more fruticose taxa were found in old growth stands, a possible age/management effect.  The proportion of atranorin-containing taxa was slightly lower in HH stands, while the proportion of usnic-acid containing taxa was lowest in even-aged NH stands and highest in old growth HH stands, suggesting both management and habitat effects on chemistry. The proportion of pored taxa was not clearly linked to either habitat or management. The proportion of apotheciate taxa was higher in even-aged NH (23.3%) stands than in uneven-aged (17.7%) and old growth stands (17.4%).  Uneven-aged NH stands showed a higher proportion of sorediate taxa (62.6%) than even-aged (56.1%) and old growth (56.7%) stands.  Uneven-aged HH stands had a higher proportion of isidiate taxa (30.5%) compared to old growth stands (23.8%).  These findings suggest some links between reproductive mode and management. This study suggests that management strategies may affect not only alpha diversity, but also phylogenetic diversity and the proportion of taxa with various morphological and chemical traits.