Lichen

Lichens map the surfaces of bark in finely tuned patterns—each species occupying the microhabitat it can tolerate.
Sunlit ridges, shaded hollows, frost-catching fissures, and nutrient-enriched pockets all host their own specialists.
Together they form a quiet, living mosaic stitched into the trunk.

Nitrogen-Enriched Bark

When bark becomes enriched with reactive nitrogen — from bird perching, agricultural drift, roadside exposure, or urban air — the lichen community shifts. Bright orange and yellow species thrive, while more sensitive lichens disappear.

This assemblage shows a classic nitrogen bark community, where nitrophile and nitrogen-tolerant species coexist on oak bark.

Species Pages

For identification notes and comparative study, see the Lichen Field Notes.

Collection

Field Notes

• Lichen Index
• Lichen Identification
• Four Common Bark Lichen Comparison
• Minnesota Lichen Guide

References

• Natural Resources Conservation Service - U.S. Department of Agriculture
• iNaturalist
• Minnesota Seasons.com
• Consortium of Lichen Herbaria