Abstract
Large-scale ecological research (i.e., macroecology, biogeography, and landscape ecology) is limited by the inability to have robust experimental replication due to scale and spatial changes in ecological patterns. Model systems may offer one solution to this challenge. We propose that considering smaller patterns in the context of larger ones (here, patches of lichen thalli on the trunks of trees) as model systems for large-scale research, can provide sufficient replication. Appropriate model systems will facilitate experimentation to elucidate links between spatial ecological patterns and processes. To function as replicate landscape units, patterns of patches should not differ significantly between trees across a sampling area of interest. We compared a previously-demonstrated model system of patches of lichen on balsam fir (Abies balsamea) tree trunks within a single small lichen-rich forest stand on the Avalon Peninsula in Newfoundland, Canada to a set of more widely dispersed trees of two species (balsam fir and yellow birch, Betula alleghaniensis) to assess if this model system could be useful across broader spatial extents. We found that lichen composition generally followed consistent patterns between north and south sides of the tree, as well as along an elevational gradient up the trunk at both the more constrained, and at the more extensive, sampling extents. However, the reliability of the trees as model landscapes varied by tree species and with the suite of lichens included. Considering lichens on trees as a model landscape system can allow sufficient replication in experimentation to address questions about spatial ecological patterns and thus provide a useful model system for research in landscape ecology and biogeography.