Treesearch

Ecological restoration treatments using thinning and prescribed burning have been proposed to reverse the decline of old-growth ponderosa pines in the Southwest. However, long-term data on the effectiveness of such treatments are lacking. In 1993-1994, two ecological restoration treatments and a control were established at the G. A. Pearson Natural Area (GPNA) near Flagstaff, AZ. The thinned treatment removed many postsettlement-aged trees to create tree density and stand structure similar to pre-Euro- American forests. The thinned + burned treatment included prescribed burning of the...

The decision whether to seed with native species following restoration treatments should be based on existing vegetation, species present in or absent from the soil seed bank, past management history, microclimate conditions and soils. We installed three permanent monitoring plots in two areas (total 18.6 ha) at Mt. Trumbull, AZ. Trees were thinned and the sites burned in 1996 and 1997. A 5 ha area was seeded with native shrub, grass and forb species; the remaining 13.6 ha were unseeded. Pretreatment species richness ranged from none to five species per plot. We recorded 13 graminoid and...

Dendroecological forest reconstruction techniques are used to estimate presettlement structure of northern Arizona ponderosa pine forests. To test the accuracy of these techniques, we remeasured 10 of the oldest forest plots in Arizona, a subset of 51 historical plots established throughout the region from 1909 to 1913, and compared reconstruction outputs to historical data collected. Results of this analysis revealed several distinct sources of error: (1) After about 90 years, 94 percent of the recorded trees were relocated and remeasured, but approximately three trees/ha were missing in...

An unlogged and ungrazed ponderosa pine/Douglas-fir landscape in the Colorado Front Range provides critical information for restoring forests in the South Platte watershed. A frame-based model was used to describe the relationship among the four primary patch conditions in the 35-km2 Cheesman Lake landscape: (1) openings, (2) ponderosa pine forest, (3) ponderosa pine/Douglasfir forest, and (4) persistent old growth. Each condition is possible over time at any nonriparian site, with fire and tree recruitment the primary processes causing changes from one condition to another. The Forest...

Lack of Euro-American disturbance, except fire suppression, has preserved the patterns of forest structure that resulted from the presettlement disturbance regime in a ponderosa pine/Douglas-fir landscape at Cheesman Lake in the Colorado Front Range. A mixed-severity fire regime and variable timing of tree recruitment created a heterogeneous forest age structure with considerable old growth. Surrounding forests subjected to human alteration since the late 1800s are younger, denser, and more continuous. We present preliminary data from a study of fire history and age structure. We mapped...

Potential fire behavior was compared under dry, windy weather conditions in 12 ponderosa pine stands treated with alternative thinning prescriptions in the wildland/urban interface of Flagstaff, Arizona. Prior to thinning, stands averaged 474 trees/ acre, 158 ft2/acre basal area, crown bulk density 0.0045 lb/ft3, and crown base height 19.2 ft. Three thinning treatments differing in residual tree density were applied to each of three stands (total of nine treated, three control). Treatments were based on historic forest structure prior to Euro-American settlement and disruption of the...

Ponderosa pine (Pinus ponderosa) trees established before Euro-American settlement are becoming rare on the landscape. Prescribed fire is the prime tool used to restore ponderosa pine ecosystems, but can cause high mortality in presettlement ponderosa pines. This study uses retrospective techniques to estimate mortality from prescribed burns within Grand Canyon National Park (GCNP). Live and recently dead presettlement ponderosa pines were sampled in four prescribed burns and three adjacent unburned areas. Presettlement ponderosa pine mortality (not including areas of crownfire) was higher...

Vegetation and fuel loading plots were monitored and sampled in wilderness areas treated with prescribed fire. Changes in ponderosa pine (Pinus ponderosa) forest structure tree species and fuel loading are presented. Plots were randomly stratified and established in burn units in 1995. Preliminary analysis of nine plots 2 years after burning show litter was reduced 54.3 percent, duff was reduced 34.7 percent, ponderosa pine tree density in the 10.2 cm to 30.5 cm d.b.h. (diameter at breast height) size class was reduced 18 percent, and ponderosa pine tree density greater than 61.2 cm d.b.h....

Prescribed fire was used to reduce fuel loading and tree densities. Permanent vegetation and fuel loading plots were randomly established within prescribed burn units. The plots were established in 1995 and were sampled, immediately postburn (within 1 month of the fire), 1 year after the burn, and 2 years after the burn. The prescribed burns were implemented in August of 1995. Preliminary analysis of 11 plots shows fuel loading was reduced from 31.9 tons/acre to 11.4 tons/acre immediate postburn. White fir (Abies concolor) overstory was reduced 35 percent, poles 52 percent, and seedlings...

Since 1992 a collaborative group of fire scientists, forest conservationists, and Federal resource specialists have been developing proposals for a Research Natural Area (RNA) in the Warner Creek Fire area on the Willamette National Forest in Oregon. Inspired by these proposals, the Oregon Natural Heritage Plan created the new category of "Fire Process RNAs" in order to protect landscape-scale areas for dynamic ecosystem disturbance and succession processes resulting from wildland fires. Fire Process RNAs have many values for basic wildland fire research, ecosystem restoration, biodiversity...