Plant community ecology<\/p>\n
We study changes in southwestern plant communities since Euro-American settlement due to changing climate and land use.\u00a0 We quantify the importance of these legacy effects to determine their importance in current and future plant community structure and pattern.\u00a0 In particular, we quantify changes in tree, shrub, and herbaceous (grass and forb) structure, composition, spatial pattern, and associated disturbance regimes over the past 100+ years. The vegetation types we focus on are ponderosa pine, lower mixed conifer, montane grasslands, and meadows.\u00a0 All of these vegetation types were affected by a number of factors that occurred almost simultaneously with Euro-American settlement including climate fluctuations (and periodic droughts), livestock overgrazing, fire exclusion and suppression, and timber harvest.\u00a0 The combined effects of changing climate and rapid changes in disturbance regimes at the turn of the 20th c. disrupted the natural disturbance-recovery cycles and have implications for long-term alterations in plant community states and ecosystem processes across the Southwest.<\/p>\n
We use a variety of tools to examine vegetation change in these systems, including direct measurements of age, structure, composition, and spatial pattern.\u00a0 We use dendrochronological techniques to determine temporal patterns in individual tree growth and to reconstruct stand conditions.\u00a0 Spatial statistics and GIS are used to examine patch-level changes over time. We have examined pre-settlement (old-growth) and post-settlement tree patterns, tree encroachment on meadows, and sudden aspen decline (mortality) using these techniques. We also map vegetation on fine-grained (1-m2), permanent chart quadrats, and use the annually mapped data to explore links among herbaceous plant demography, climate, and land use.\u00a0 Lastly, we helped initiate a long-term forest restoration experiment on the USFS Rocky Mountain Research Station (RMRS), Fort Valley Experimental Forest, where we continue to monitor the responses of tree growth, grass, and forb production, and fuels to tree thinning and prescribed burning.<\/p>\n
Our lab, in Northern Arizona University\u2019s (NAU) School of Forestry, works together with the NAU Ecological Restoration Institute (ERI), and the USFS RMRS and other research and land management agencies to fund, implement, and publish results from the projects mentioned above.\u00a0 Recognizing how the natural and anthropogenic disturbances shaped today’s southwestern plant communities provide critical baseline information for the natural range of variability and ecosystem resilience concepts, and for ecosystem restoration and other land management efforts.<\/p>\n\n