Questions
Questions in this section frequently come up in workshops, field tours, symposia, and general discussions related to pinyon-juniper woodlands. They are closely linked to woodland ecology, resilience, resistance to invasives, and restoration. Most are addressed in more depth in referenced citations and Miller et al. 2019.
This question (Distinguishing Old-Growth (Presettlement) from Post-Settlement Woodlands) is answered in the Restoration Tools and Concepts section of the website.
The largest western juniper is found in eastern Oregon. Its dimension are 233 inches in circumference (6.2 ft in diameter), 68 ft tall, and 44 ft canopy diameter. The tree, several or more centuries old grows on a relatively productive site with very sandy soils. There is a co-state champion with dimensions of: 223 CBH,…
Over two dozen species of Indian paintbrush grow in the Intermountain Region, many of these are associated with pinyon-juniper woodlands. The genus Castilleja is hemiparasitic, meaning the plants obtain some important nutrients through parasitism. Most Intermountain Castilleja species are fire resistant, sprouting from the root crown located below the soil surface.
The northern limits of singleleaf pinyon appear to correspond to the strength of cold Pacific fronts resulting in rapid cycling of warming periods interrupted by cold periods during late winter and early spring (Nowak et al. 1994a; West et al. 1978a). These warm periods encourage pinyon to break dormancy early, making them susceptible to frost…
In the literature, the terms presettlement, persistent, and old-growth are often used for woodlands existing on the landscape prior to Eurasian settlement. Although often used interchangeably, each has a different meaning and may or may not be one and the same. Presettlement woodlands established prior to Eurasian settlement and introduction of livestock around the 1860s…
Fire is five times more likely to burn in the northern Great Basin than in the southern Great Basin and Colorado Plateau (Littell et al. 2009). While the abundance and distribution of invasive annual grasses are likely influencing present-day regional fire occurrences in the northwestern Great Basin, Columbia Basin, and Snake River Basin, they do…
Yes and no. Shrubs rarely persist beneath a closed tree canopy, especially sagebrush. However, deep rooted perennial grasses have been observed to persist on sites with deep soils and where restrictive layers (e.g. clay accumulation layer called an argillic), reducing water capture and storage are absent or weakly developed. Photos of two different pinyon-juniper sites,…
Increasing temperatures and reduced summer precipitation are projected to favor expansion of cheatgrass (Bromus tectorum) at higher elevations. The greater the change in summer conditions, the greater the expected shift in cheatgrass (Bradley et al. 2016). Although cheatgrass will probably decline at lower elevations, red brome (B. rubens) already present throughout the Great Basin will…
Several studies found that increased atmospheric CO2 concentrations resulted in increased cheatgrass (Bromus tectorum), when soil water and nutrients were not limiting establishment and growth (Hungate et al. 1996; Larigauderie et al. 1988; Nowak et al. 2004).
Response of cheatgrass (Bromus tectorum) the first growing season on a depleted site following fire depends on seed source. Abundance of post-fire cheatgrass seed is directly related to: the amount of seed in the seed-pool prior to the fire the amount seed combusted by fire, which is largely related to the abundance and types of…