Early succession following clearcutting of aspen communities in Northern Utah

Changes in aspen reproduction and undergrowth production and composition were recorded over a 3-year period following clearcutting. Aspen suckers increased from 2,300 per hectare prior to cutting to a maximum of 44,000 per hectare the second post-cut year, and dropped to approximately 25,000 per hectare by the third year. Undergrowth production on the cut units increased from 1,013 kg/ha prior to cutting to 3,000 kg/ha after three growing seasons; production on the uncut control areas increased from 1,199 kg/ha to 1,539 kg/ha during this period. The significant increase in undergrowth is attributed to the reduction in competition from the removal of the aspen overstory. Clearcutting appeared to increase the proportion of shrubs in the undergrowth and decrease the proportion of forbs. A similarity index comparing the cut and uncut areas suggested that the greatest change in species composition occurred the first year after cutting, with a gradual return towards the precut conditions.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Early succession in aspen communities following fire in western Wyoming

Aspen clones in varying degrees of deterioration were burned in northwestern Wyoming in an attempt to regenerate the site. Large numbers of aspen suckers are necessary to perpetuate these stands under current heavy ungulate use. Sucker numbers doubled the second year after burning and by the end of the third year had returned to near preburn levels of 15,000-20,000 suckers per hectare. This slight increase in sucker numbers is probably not sufficient to regenerate the stands under current browsing pressures. Total understory production declined the first year following fire and then increased to 3,600 kg/ha the second year-almost double preburn conditions. Production decreased the third year to about one-third greater than before burning. Forb and grass production increased and shrubs decreased as a result of burning. Fireweed (Epilobium angustifolium) was the largest post-fire contributor to total understory production.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Influences of infrequent fire, elevation and pre-fire vegetation on the persistence of quaking aspen (Populus tremuloides Michx.) in the Flat Tops area, Colorado, USA

Aim: The recent concern that quaking aspen (Populus tremuloides Michx.) has been declining in parts of western North America due to fire suppression is largely based on trends during the latter part of the 20th century. The aim of the current study was to compare the extent of aspen in the modern landscape with its extent in the late 19th century prior to fire suppression, and to assess the effects of elevation, late-19th century fires, and pre-fire forest composition on the successional status of aspen. Location: North-west Colorado, USA. Methods: We used a georeferenced 1898 map and modern maps to examine trends in aspen dominance since the late 19th century in a 348,586 ha area of White River and Routt National Forests in north-western Colorado. Stand age and structure were sampled in 30 stands. Results: We found no evidence of overall aspen decline over this period. In fact, aspen distribution has increased in parts of the study area following severe fires in the late 19th century in forests that were previously dominated by conifers. Aspen persistence and increase was especially pronounced at elevations below 3000 m a.s.l. Most 120-year-old post-fire stands that are presently being successionally replaced by conifers were dominated by conifers prior to the last severe fire. Main conclusions: Human perceptions of ecosystems are often on time scales that are shorter than the cycles of natural variation within those ecosystems. This disparity may lead to an underestimation of the range of natural variability of ecosystem patterns and processes. The appropriate temporal scale of inquiry is necessary for the correct understanding of natural variation in ecosystems. © 2006 The Authors

Storage and Stability of Soil Organic Carbon in Aspen and Conifer Forest Soils of Northern Utah

This study compares the amount, distribution, and stability of soil organic carbon (SOC) in six paired quaking aspen (Populus tremuloides Michx) and conifer plots at three locations in northern Utah, to assess the influence of vegetation cover and other biotic and abiotic drivers on SOC storage capacity in seasonally dry environments. Aspen soils accumulated significantly more SOC in the mineral soil (0–60 cm) (92.2 ± 26.7 Mg C ha−1 vs. 66.9 ± 18.6 Mg C ha−1 under conifers), and despite thicker O horizons under conifers that contained higher amounts of SOC (11.6 ± 8.8 Mg C ha−1 under conifers vs. 1.65 ± 0.38 Mg C ha−1 in aspen), across all sites SOC storage was 25% higher under aspen. Shallow soil cores (0–15 cm) did not indicate significant differences in SOC with vegetation type. The SOC under aspen was also more stable, indicated by well-developed mollic epipedon (A horizon 38–53-cm thick vs. 5.5–34 cm under conifers), slower turnover of surficial SOC deduced from long-term laboratory incubations (67.7 ± 15.7 g CO2–C per kg C for aspen vs. 130.9 ± 41.3 g CO2–C per kg C for conifer soils), and a greater preponderance of mineral-associated SOC (55±13% in aspen vs. 41±13% in conifer). Aspen soils were generally wetter and we hypothesize that rapid litter turnover coupled with greater water supply may have caused greater downward redistribution and adsorption of dissolved organic carbon (DOC) in aspen soils