Matching Items (3)
Description
Two nearly homogenous 60 acre watersheds near Heber, Arizona, within the Apache-Sitgreaves National Forest, were burned at moderate and high severities during the 2002 Rodeo-Chediski wildfire. Each watershed had 30 permanent plots located on it from earlier studies. In 2011, nearly 10 years following the fire, the plots were re-measured to determine how fire severity affects the long term vegetative recovery of this ecosystem; specifically herbaceous production and tree regeneration and density. Canopy cover, litter depth, herbaceous weight, herbaceous cover and shrub cover are vital indicators of herbaceous production, and were found to be significantly different between the sites. Canopy cover and litter depth were found to be significantly higher on the moderate site while herbaceous weight, herbaceous cover and shrub cover were found to be significantly higher on the high site. Tree densities of the three present tree species, ponderosa pine, alligator juniper, and gambel oak, were measured and divided into five size classes to distinguish the diversity of the communities. The mean densities for each species and size class were analyzed to determine if there were any statistically significant differences between the sites. Ponderosa pine saplings (regeneration) were found to have no significant differences between the sites. Juniper and oak saplings were found to be significantly higher on the high site. The remaining four ponderosa pine size classes were found to be significantly higher on the moderate site while the remaining four size classes for juniper and oak were found to have no statistical differences between the sites. Further analysis of the tree proportions revealed that the ponderosa pine species was significantly higher on the moderate site while juniper and oak were significantly higher on the high site. Species specific proportion analysis showed that the ponderosa pine size classes were significantly different across the sites while the juniper and oak size classes showed no significant differences between the sites. Within the ponderosa pine size classes, saplings were found to be significantly higher on the high site while the remaining four classes were significantly higher on the moderate site.
ContributorsNeeley, Heidi L (Author) / Alford, Eddie (Thesis advisor) / Pyne, Stephen (Committee member) / Brady, Ward (Committee member) / Arizona State University (Publisher)
Created2012
Description
Understanding the effects of fire on the Sonoran Desert is of critical importance as rising temperatures and changing weather patterns increase the frequency and size of wildfires. Seed banks are an important component in post-fire landscape recovery as the seeds that remain in the soil are an indicator of a landscape’s future trajectory. The purpose of this study is to determine the lasting impacts of fire on the soil seed bank of the Sonoran Desert and to identify potential concerns affecting post-fire recovery and restoration. The study site was located in the Arizona Upland division of the Sonoran Desert, Arizona, United States. Soil samples were collected from five burned sites with increasing time since fire, and five nearby unburned sites used as a control. A seedling emergence test was conducted to investigate the density and richness of the seed bank of burned and unburned sites. Seed densities and species richness for sites were calculated using germination results. Findings were analyzed using non-parametric analyses comparing changes in burned and unburned sites over time.
Results found that burn status and time since fire had no significant impact on seed density. Graminoid and forb densities were statistically consistent across burn status and time since fire. While species richness was consistent across both plot types, burned samples typically had fewer species than unburned samples. Burned and unburned plots revealed a dominance of annual species with limited presence of woody perennials. While seed densities and species richness are relatively unchanged across burned and unburned sites over time, the lack of woody perennials in the seed bank raises concerns about landscape recovery trajectories in burned sites. These results suggest that restoration efforts focused on maintaining the presence of woody trees and shrubs in the landscape may have the most impact.
ContributorsCountryman, Kristen (Author) / Makings, Elizabeth (Thesis advisor) / Pigg, Kathleen (Thesis advisor) / Lata, Mary (Committee member) / Arizona State University (Publisher)
Created2023
Description
The recent emergence of global ‘megafires’ has made it imperative to better understand the role of humans in altering the size, distribution, and seasonality of fires. The dynamic relationship between humans and fire is not a recent phenomenon; rather, fire has deep roots in our biological and cultural evolution. Because of its long-term perspective, archaeology is uniquely positioned to investigate the social and ecological drivers behind anthropogenic fire. However, the field faces challenges in creating solution-oriented research for managing fire in the future. In this dissertation, I originate new methods and approaches to archaeological data that enable us to interpret humans’ long-term influences on fire regimes. I weave together human niche construction theory and ecological resilience, creating connections between archaeology, paleoecology, and fire ecology. Three, stand-alone studies illustrate the usefulness of these methods and theories for charting changes in land-use, fire-regimes, and vegetation communities during the Neolithic Transition (7600 - 3800 cal. BP) in eastern Spain. In the first study (Ch. II), I analyze archaeological survey data using Bayesian methods to extract land-use intensities from mixed surface assemblages from a case study in the Canal de Navarrés. The second study (Ch. III) builds on the archaeological data collected computational model of landscape fire, charcoal dispersion, and deposition to test how multiple models of natural and anthropogenic fire activity contributed to the formation a single sedimentary charcoal dataset from the Canal de Navarrés. Finally, the third study (Ch. IV) incorporates the modeling and data generated in the previous chapters into sampling and analysis of sedimentary charcoal data from alluvial contexts in three study areas throughout eastern Spain. Results indicate that anthropogenic fire played a significant role in the creation of agricultural landscapes during the Neolithic period, but sustained, low-intensity burning after the late Neolithic period maintained the human created niche for millennia beyond the arrival of agro-pastoral land-use. With global fire activity on the rise, it is vital to incorporate perspectives on the origins, development, and maintenance of human-fire relationships to effectively manage fire in today’s coupled social-ecological landscapes.
ContributorsSnitker, Grant (Author) / Barton, Michael (Thesis advisor) / Morehart, Christopher (Committee member) / Franklin, Janet (Committee member) / Arizona State University (Publisher)
Created2019