93 years of stand density and land-use legacy research at the Coulter Ranch Study Site

In 1913, the Fort Valley Experimental Forest initiated an unprecedented case-study experiment to determine the effects of harvesting methods on tree regeneration and growth on a ponderosa pine-Gambel oak forest at Coulter Ranch in northern Arizona. The harvesting methods examined were seed-tree, group selection, and light selection. In addition, the effects of livestock grazing (excluded or not) were examined. We revisited the Coulter Ranch Study Site to examine the effects of these treatments on historical (1913) and contemporary (2003-2006) stand density and tree size. The key finding was that while initial 1913 harvests reduced average pine density by one- to two-thirds, tree densities increased from three to nine times those prior to harvest over the 93-year period. The greatest increase was in the seed-tree method

IMPORTANCE OF BURROW-ENTRANCE MOUNDS OF GUNNISON'S PRAIRIE DOGS (CYNOMYS GUNNISONI) FOR VIGILANCE AND MIXING OF SOIL

Aboveground mounds and underground burrows are multifunctional and influence behavior and habitat of Gunnison's prairie dogs (Cynomys gunnisoni). Four colonies were studied June September 2004 to examine function of mounds with respect to vigilance for predators, and to estimate magnitude of soil mixed by these prairie dogs. Frequency of vigilance atop mounds increased in taller vegetation and individuals at perimeters of colonies oriented toward the outside more frequently than to the interior of colonies. Mounds accounted for an average of 10,374 kg of soil/ha that was excavated from the burrow. This mass of subsoil moved to the surface and the 7-17 m(3) of air in the burrow make the geomorphic effect of prairie dogs potentially significant

Forest structure and tree recruitment changes on a permanent historical Cinder Hills plot over a 130-Year Period

We examined forest structure, tree recruitment, and spatial pattern over a 130-year period on cinder soils in northern Arizona. Data were collected from a 3.24 ha permanent, stem-mapped plot established in 1909. This site is unique in that it represents ponderosa pine (Pinus ponderosa Laws. var. scopulorum Engelm.) growing on black cinder soils, which are of limited extent in the Southwest. Tree diameter, tree density and spatial data reconstructed from 1874 and actual measurements from 1909 and 2004 were compared, and the current stand age-structure of living trees was examined. Unlike most studies of stand dynamics in the Southwest, this site has experienced little change in structure or spatial pattern between 1874 and 2004. This difference is thought to reflect the unique environmental conditions associated with black cinder soils

Early thinning experiments established by the Fort Valley Experimental Forest

Between 1925 and 1936, the Fort Valley Experimental Forest (FVEF) scientists initiated a study to examine a series of forest thinning experiments in second growth ponderosa pine stands in Arizona and New Mexico. These early thinning plots furnished much of the early background for the development of methods used in forest management in the Southwest. The plots ranged from 0.1 ac to 5 ac (0.04 ha to 2.02 ha) in size and many of the thinning plots and control plots were remeasured at 2 to 10-year intervals until the 1940s. The first thinning plots in the Southwest, called the White Spar plots, were established in 1925 on the Prescott National Forest. The residual trees on the thinned White Spar plots maintained higher growth rates than the control until the mid 1970s. The results from these early stand thinning experiments led G.A. Pearson, Director of FVEF, and others to largely abandon uniform thinning treatments and adopt the crop-tree thinning method as an improved method for thinning southwestern ponderosa pine stands

"Growing trees backwards": Description of a stand reconstruction model

We describe an individual-tree model that uses contemporary measurements to "grow trees backward" and reconstruct past tree diameters and stand structure in ponderosa pine dominated stands of the Southwest. Model inputs are contemporary structural measurements of all snags, logs, stumps, and living trees, and radial growth measurements, if available. Key steps include the application of inverse decay functions to estimate snag and log death dates, and the estimation of tree size in the reconstruction year via radial growth data or accrued basal area increment. The model is provided as a function for R, and can be modified for other species and regions

Past, present, and future old growth in frequent-fire Conifer Forests of the Western United States

Old growth in the frequent-fire conifer forests of the western United States, such as those containing ponderosa pine (Pinus ponderosa), Jeffrey pine (P. jeffreyi), giant sequoia (Sequioa giganteum) and other species, has undergone major changes since Euro-American settlement. Understanding past changes and anticipating future changes under different potential management scenarios are fundamental to developing ecologically based fuel reduction or ecological restoration treatments. Some of the many changes that have occurred in these forests include shifts from historically frequent surface fire to no fire or to stand-replacing fire regimes, increases in tree density, increased abundance of fire-intolerant trees, decreases in understory productivity, hydrological alterations, and accelerated mortality of old trees. Although these changes are widespread, the magnitude and causes of changes may vary within and among landscapes. Agents of change, such as fire exclusion or livestock grazing, likely interacted and had multiple effects. For example, historical ranching operations may have altered both fire regimes and understory vegetation, and facilitated institutional fire exclusion through fragmentation and settlement. Evidencem exists for large variation in presettlement characteristics and current condition of old growth across this broad forest region, although there are many examples of striking similarities on widely distant landscapes. Exotic species, climate change, unnatural stand-replacing wildfires, and other factors will likely continue to degrade or eradicate old growth in many areas. As a policy of fire exclusion is proving to be unsustainable, mechanical tree thinning, prescribed fire, or wildland fire use will likely be key options for forestalling continued eradication of old growth by severe crown fires. For many practical and societal reasons, the wildland–urban interface may afford some of the most immediate opportunities for re-establishing old growth typical of presettlement forests resistant to crown fires

Quantifying forest reference conditions for ecological restoration: The Woolsey Plots

Sixty-six of the approximately 140 original historical plots (or 47percent) have been relocated on eight National Forests thus far. Of these 66 relocated plots 0 (0/13) are spruce-fir, 13 (13/29) are mixed conifer, and the remainder 53 (53/98) are dominated by ponderosa pine (at least historically pine dominated). This study focused on the ponderosa pine-dominated plots, of which we have relocated over 54 percent. NOTE: This total does NOT include those historical plots located on the Long Valley Experimental Forest near Clints Well, AZ