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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
Tree Canopy Types Constrain Plant Distributions In Ponderosa Pine- Gambel Oak Forests, Northern Arizona, Scott R. Abella
Tree Canopy Types Constrain Plant Distributions In Ponderosa Pine- Gambel Oak Forests, Northern Arizona, Scott R. Abella
Public Policy and Leadership Faculty Publications
Trees in many forests affect the soils and plants below their canopies. In current high-density southwestern ponderosa pine (Pinus ponderosa) forests, managers have opportunities to enhance multiple ecosystem values by manipulating tree density, distribution, and canopy cover through tree thinning. I performed a study in northern Arizona ponderosa pine-Gambel oak (Quercus gambelii) forests to measure the influences of tree canopy types on understory plant communities and soil properties. On ten 2.5-acre (1-ha) sites, I sampled five 43-ft2 (4-m2) plots below each of the following five canopy types: openings; single ponderosa pine; and Gambel oak single stems, dispersed clumps, and thickets. …
Managing Gambel Oak In Southwestern Ponderosa Pine Forests: The Status Of Our Knowledge, Scott R. Abella
Managing Gambel Oak In Southwestern Ponderosa Pine Forests: The Status Of Our Knowledge, Scott R. Abella
Public Policy and Leadership Faculty Publications
Gambel oak (Quercus gambelii) is a key deciduous species in southwestern ponderosa pine (Pinus ponderosa) forests and is important for wildlife habitat, soil processes, and human values. This report (1) summarizes Gambel oak’s biological characteristics and importance in ponderosa pine forests, (2) synthesizes literature on changes in tree densities and fire frequencies since Euro-American settlement in pine-oak forests, (3) suggests management prescriptions for accomplishing various oak management objectives (for example, increasing diameter growth or acorn production), and (4) provides an appendix containing 203 Gambel oak literature citations organized by subject. Nine studies that reconstructed Gambel oak density changes since settlement …
Gambel Oak Growth Forms: Management Opportunities For Increasing Ecosystem Diversity, Scott R. Abella
Gambel Oak Growth Forms: Management Opportunities For Increasing Ecosystem Diversity, Scott R. Abella
Public Policy and Leadership Faculty Publications
Gambel oak (Quercus gambelii) clones have several different growth forms in southwestern ponderosa pine (Pinus ponderosa) forests, and these growth forms each provide unique wildlife habitat and resource values. The purposes of this note are to review published growth-form classifications for Gambel oak, provide examples of ecological effects of different growth forms, and summarize management strategies for promoting desired growth forms. Four different growth-form classifications have been published, which generally recognize variants of three basic forms: shrubby thickets of small-diameter stems, pole-sized clumps, and large trees. These growth forms exemplify ecological and management tradeoffs. For example, shrubby forms provide browse …
Changes In Gambel Oak Densities In Southwestern Ponderosa Pine Forests Since Euro-American Settlement, Scott R. Abella, Peter Z. Fule
Changes In Gambel Oak Densities In Southwestern Ponderosa Pine Forests Since Euro-American Settlement, Scott R. Abella, Peter Z. Fule
Public Policy and Leadership Faculty Publications
Densities of small-diameter ponderosa pine (Pinus ponderosa) trees have increased in southwestern ponderosa pine forests during a period of fire exclusion since Euro-American settlement in the late 1800s. However, less well known are potential changes in Gambel oak (Quercus gambelii) densities during this period in these forests. We reviewed published literature to summarize changes in oak density in ponderosa pine forests over the past 140 years and evaluated the possibility that large-diameter oaks have decreased in density. All nine studies examining oak density changes found that densities of small-diameter oaks have escalated. Increases ranged from 4- to more than 63-fold. …
Estimating Soil Seed Bank Characteristics In Ponderosa Pine Forests Using Vegetation And Forest-Floor Data, Scott R. Abella, Judith D. Springer
Estimating Soil Seed Bank Characteristics In Ponderosa Pine Forests Using Vegetation And Forest-Floor Data, Scott R. Abella, Judith D. Springer
Public Policy and Leadership Faculty Publications
Soil seed banks are important for vegetation management because they contain propagules of species that may be considered desirable or undesirable for site colonization after management and disturbance events. Knowledge of seed bank size and composition before planning management activities facilitates proactive management by providing early alerts of exotic species presence and of abilities of seed banks to promote colonization by desirable species. We developed models in ponderosa pine (Pinus ponderosa) forests in northern Arizona to estimate the size and richness of mineral soil seed banks using readily observable vegetation and forestfloor characteristics. Regression models using three or fewer predictors …
Plant Recruitment In A Northern Arizona Ponderosa Pine Forest: Testing Seed- And Leaf Litter- Limitation Hypotheses, Scott R. Abella
Plant Recruitment In A Northern Arizona Ponderosa Pine Forest: Testing Seed- And Leaf Litter- Limitation Hypotheses, Scott R. Abella
Public Policy and Leadership Faculty Publications
Seed availability and leaf litter limit plant establishment in some ecosystems. To evaluate the hypothesis that these factors limit understory plant recruitment in Pinus ponderosa forests, I conducted a seeding and litter removal experiment at six thinned sites in the Fort Valley Experimental Forest, northern Arizona. Experimental seeding of four native species (Penstemon virgatus, Erigeron formosissimus, Elymus elymoides, and Festuca arizonica) and raking of litter occurred in 2005. Seeding resulted in a substantial recruitment of 14 to 103 seedlings/m2 (1 to 10/ft2) one month after seeding for two species (P. virgatus and E. elymoides), but these densities subsequently declined by …
Fire Effects On Gambel Oak In Southwestern Ponderosa Pine-Oak Forests, Scott R. Abella, Peter Z. Fule
Fire Effects On Gambel Oak In Southwestern Ponderosa Pine-Oak Forests, Scott R. Abella, Peter Z. Fule
Public Policy and Leadership Faculty Publications
Gambel oak (Quercus gambelii) is ecologically and aesthetically valuable in southwestern ponderosa pine (Pinus ponderosa) forests. Fire effects on Gambel oak are important because fire may be used in pine-oak forests to manage oak directly or to accomplish other management objectives. We used published literature to: (1) ascertain historical fire regimes in pine-oak forests, (2) discern prescribed burning effects on Gambel oak survival and diameter growth, and (3) provide suggestions for using fire to manage oak. Frequent fire is part of Gambel oak’s historical environment, as historical fire return intervals often averaged less than 10 years in pine-oak forests. More …
Forest-Floor Treatments In Arizona Ponderosa Pine Restoration Ecosystems: No Short-Term Effects On Plant Communities, Scott R. Abella, W. Wallace Covington
Forest-Floor Treatments In Arizona Ponderosa Pine Restoration Ecosystems: No Short-Term Effects On Plant Communities, Scott R. Abella, W. Wallace Covington
Public Policy and Leadership Faculty Publications
Leaf litter accumulation during fire exclusion and increases in tree density in postsettlement southwestern Pinus ponderosa forests may limit the establishment of understory vegetation. We performed an experiment in P. ponderosa forests of northern Arizona to ascertain plant community responses to forest-floor scarification and Oi removal on thirty-six 100-m2 plots overlaid on an existing ecological restoration experiment that involved tree thinning and prescribed burning. Constrasting with findings from many other forest types, forest-floor treatments had no effect on community diversity or composition during the 2-year experiment. Sørensen similarities were as high as 97% between posttreatment years within treatments; and successional …
Past, Present, And Future Old Growth In Frequent-Fire Conifer Forests Of The Western United States, Scott R. Abella, W. Wallace Covington, Peter Z. Fule, Leigh B. Lentile, Andrew J. Sanchez Meador, Penelope Morgan
Past, Present, And Future Old Growth In Frequent-Fire Conifer Forests Of The Western United States, Scott R. Abella, W. Wallace Covington, Peter Z. Fule, Leigh B. Lentile, Andrew J. Sanchez Meador, Penelope Morgan
Public Policy and Leadership Faculty Publications
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 …
Canopy-Tree Influences Along A Soil Parent Material Gradient In Pinus-Ponderosa-Quercus Gambelii Forests, Northern Arizona, Scott R. Abella, Judith D. Springer
Canopy-Tree Influences Along A Soil Parent Material Gradient In Pinus-Ponderosa-Quercus Gambelii Forests, Northern Arizona, Scott R. Abella, Judith D. Springer
Public Policy and Leadership Faculty Publications
ABELLA, S. R. (Public Lands Institute and School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-2040) AND J. D. SPRINGER (Ecological Restoration Institute, Northern Arizona University, Flagstaff, AZ 86011-5017). Canopy-tree influences along a soil parent material gradient in Pinus ponderosa- Quercus gambelii forests, northern Arizona. J. Torrey Bot. Soc. 135: 26–36. 2008.—The distribution of canopy trees can impose within-site patterns of soil properties and understory plant composition. At ten sites spanning a soil parent material gradient in northern Arizona Pinus ponderosa-Quercus gambelii forests, we compared soils and plant composition among five canopy types: openings, Pinus ponderosa …
Tree Thinning And Prescribed Burning Effects On Ground Flora In Arizona Ponderosa Pine Forests: A Review, Scott R. Abella
Tree Thinning And Prescribed Burning Effects On Ground Flora In Arizona Ponderosa Pine Forests: A Review, Scott R. Abella
Public Policy and Leadership Faculty Publications
Ground flora is an important response variable to monitor after tree thinning and prescribed burning treatments designed to restore Arizona ponderosa pine (Pinus ponderosa P.& C. Lawson) forests. This paper reviews published literature on the effects of thinning and burning on ground flora in Arizona ponderosa pine forests in five main categories of research: ground flora biomass, species diversity, plant community composition, population processes, and individual species ecology. Research published to date suggests that thinning and burning generally increase ground flora biomass, whereas other categories of research such as community composition and population processes have been little studied in Arizona …