Climate and epiphytic macrolichen communities in the Four Corners region of the U.S.A.
- Author:
- McCune B., Yang S., Jovan S. & Root H.T.
- Year:
- 2022
- Journal:
- Bryologist
- Pages:
- 125(1): 70–90
- Url:
- DOI: 10.1639/0007-2745-125.1.070
We used data on epiphytic lichen communities in 1215, 0.4-ha plots in the Southwest U.S.A.
collected by the Forest Inventory and Analysis (FIA) program to analyze relationships with climate. We
sought the climate variables most strongly associated with differences in epiphytic macrolichen
communities and described the nature of those relationships, including diversity, community
composition, and patterns in individual species. Five lichen community groups were strongly related
to temperature and elevation gradients, overall moisture, and summer rain. Lichen abundance was
highest in the wettest groups and lowest in the hottest and driest groups. Warm summer monsoonal
climates supported the greatest number of species across all plots and within plots. The monsoonal
pattern did not occupy a discrete geographic area, but instead formed a gradient, strongest in the
southern part of our study area, diminishing to the north and west. In contrast, hot summer monsoonal
climates had much lower within-plot richness. Hot, dry climates had the most variation in species
composition among plots, but the fewest species within each plot and across all plots. Lichen community
gradients had nonlinear relationships with combinations of climate variables rather than strong linear
relationships with any single variable, including those derivative climate variables meant to have direct
biological relevance. Relationships between air quality and community gradients were weak, potentially
overwhelmed by regional climatic variation and complex topographic gradients. Richness of particular
functional groups was more strongly related to climate than was overall species richness; functional
groups have their own climatic tolerances, owing to the physiological consequences of growth form and
photobiont. Presumably species in different functional groups have experienced their own evolutionary
tradeoffs, developing peak performance in different climates. On the other hand, overall richness was
driven by an even more complex combination of performances relative to climate and was in some
functional groups more strongly related to geographic coordinates than to climate variables. Because
climatic variables are themselves geographically structured, stronger model fit for geographic coordinates
than for climate implies some influence of large-scale historical factors (i.e., factors not clearly expressed
in modern climates, such as past climates, vegetation structure, or disturbance regimes).
Keywords: Air quality, Arizona, climate, cluster analysis, Colorado, community composition, diversity,
indicator species, monsoon, New Mexico, Nevada, nonmetric multidimensional scaling, nonparametric
multiplicative regression, Utah.
- Id:
- 34107
- Submitter:
- zdenek
- Post_time:
- Saturday, 22 January 2022 12:47