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Symposium

Session: : Ecosystem Transitions Across Ecosystems; From Basic to Applied

SYMP 19-3 - Environmental variability drives shifts in plant community composition across ecosystems

Wednesday, August 9, 2023
2:10 PM – 2:30 PM PDT
Location: 258
Perturbations like nutrient pulses and drought can cause directional shifts in community structure and function. Concurrently, changes in climate mean and variability can exacerbate the effects of perturbations on community diversity and could ultimately facilitate ecosystem transitions. Understanding how dominant and subordinate species respond to drought across ecosystems can help us learn how perturbations might cause long-term shifts in community composition. At the same time, understanding whether community shifts resulting from changing climate means and variance are greater when coupled with pulses in nutrient availability can provide insight into long-term community dynamics during ecosystem transitions. By synthesizing data from long-term experiments, we can assess how anthropogenic perturbations and climate variability drive changes in plant community dynamics and whether these changes increase the probability of ecosystem transitions.

Using data from LTER sites, we assessed how plant rarity changed across ecosystems along a precipitation gradient when subject to experimental drought. We also generated climate sensitivity functions to detect whether plant communities that were nutrient enriched responded more strongly to climate variance across ecosystems. We found that plant communities were mostly composed of core dominant species at our mesic and dryland sites, while our intermediate precipitation sites had greater evenness. Drought had no effect on the percent cover of core dominant species at the mesic site. However, at the dryland sites, percent cover of core dominant species declined in the drought treatment, while the cover of both the transient subordinate and transient dominant species increased. We also found that plant communities responded to climate variance at the dryland site but did not find plant community responses to climate variance at any of the other sites. Our results suggest that dryland plant communities may be more sensitive than mesic communities to climate anomalies and may have a higher likelihood of long-term shifts in community composition.