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Biological soil crust (BSC) communities (composed of lichens, bryophytes, and cyanobacteria) may be more dynamic on short-time scales than previously thought, requiring new and informative short-term monitoring techniques. We used repeat digital photography and image analysis, which revealed a change in area of a dominant BSC lichen, Collema tenax. The data generated correlated well with gross photosynthesis (r=0.57) and carotenoid content (r=0.53), two variables that would be expected to be positively related to lichen area. We also extracted fatty acids from lichen samples and identified useful phospholipid fatty acid (PLFA) indicators for the Collema mycobiont (20:1, 15:0, 23:0), and the Collema photobiont (18:3?3)....
Repeat photography samples were used to analyze how the structure and site-specific distribution of forests may or may not have changed during the past century in the San Juan Mountains, Colorado. Systematic evaluation of 146 photosets was combined with field observations to identify trends in vegetation change. Both conifers and deciduous trees (e.g., aspen) have increased in extent. Forest recovery from large disturbances that occurred during Euro-American settlement contributed substantially to this increase. Trees also encroached into grass/shrublands, but less than half of photosets show tree invasion, and invasion is more common in small grass/shrubland openings interspersed with forest than in large openings....