HISTORICAL ECOLOGICAL VARIABILITY OF MT. IRISH, SOUTH-EASTERN NEVADA, DERIVED FROM TREE-RING RECORDS

BIONDI, F., AND STRACHAN, S.

DendroLab, University of Nevada, Reno

In the Great Basin, land management agencies have little to no information on pre-settlement ecosystem dynamics and their driving forces, such as wildfire and climate. Long records of fire frequency, drought, and species distribution are important not only for fire management, but also for restoration efforts aimed at reducing the recent expansion of piñon-juniper woodland into sagebrush and other types of vegetation. We have begun assessing the historical variability of surface ecosystem processes (fire, precipitation, stand dynamics) for the Mt. Irish area in Lincoln County, south-eastern Nevada. This mountain is on the hydrographic boundary between the central Great Basin and the Colorado River Basin, but well within the boundaries of the floristic Great Basin. Recently completed tree-ring chronologies for the Mt. Irish area already cover the past 600+ years with annual to seasonal resolution. Both ponderosa pines and single-leaf piñons are present at the area, and non-scarred dominant trees were used to develop the tree-ring chronologies, which provide a record of past drought. Fire-scarred ponderosa pines, both living trees as well as snags and logs, are present at the area, and will be sampled to determine wildfire history. To test a possible relationship between wildfires and drought, we plan to derive a proxy-record of past wildfires using dendroclimatic reconstructions and published relationships between climate and fire occurrence. We will then be able to test this hypothesized record (and its implied relationships) by comparing the proxy wildfire record with that derived from fire-scarred trees. This approach, as far as we know, has not been tried before.