Matching Items (3)
Description
Mycorrhizal fungi form symbiotic relationships with plant roots, increasing nutrient and water availability to plants and improving soil stability. Mechanical disturbance of soil has been found to reduce mycorrhizal inoculum in soils, but findings have been inconsistent. To examine the impact of restoration practices on riparian mycorrhizal inoculum potential, soil samples were collected at the Tres Rios Ecosystem Restoration and Flood Control Project located at the confluence of the Salt, Gila, and Agua Fria rivers in central Arizona. The project involved the mechanical removal of invasive Tamarix spp.( tamarisk, salt cedar) and grading prior to revegetation. Soil samples were collected from three stages of restoration: pre-restoration, soil banks with chipped vegetation, and in areas that had been graded in preparation for revegetation. Bioassay plants were grown in the soil samples and roots analyzed for arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) infection percentages. Vegetations measurements were also taken for woody vegetation at the site. The mean number of AM and EM fungal propagules did not differ between the three treatment area, but inoculum levels did differ between AM and EM fungi with AM fungal propagules detected at moderate levels and EM fungi at very low levels. These differences may have been related to availability of host plants since AM fungi form associations with a variety of desert riparian forbs and grasses and EM fungi only form associations with Populus spp. and Salix spp. which were present at the site but at low density and canopy cover. Prior studies have also found that EM fungi may be more affected by tamarisk invasions than AM fungi. Our results were similar to other restoration projects for AM fungi suggesting that it may not be necessary to add AM fungi to soil prior to planting native vegetation because of the moderate presence of AM fungi even in soils dominated by tamarisk and exposed to soil disturbance during the restoration process. In contrast when planting trees that form EM associations, it may be beneficial to augment soil with EM fungi collected from riparian areas or to pre-inoculate plants prior to planting.
ContributorsArnold, Susanne (Author) / Stutz, Jean (Thesis advisor) / Alford, Eddie (Committee member) / Green, Douglas (Committee member) / Arizona State University (Publisher)
Created2012
Description
Now dry and broken, the Salt River once supplied a great legacy of Riparian vegetation through the Sonoran desert. This verdant landscape flourished from perennial flows of a river fed by high mountain snowmelt. However, multiple dams within those mountain canyons and channelization for the purpose of flood protection have nearly dried up the Salt. Through the process of design I examined the potential to repair, restore, and redevelop the river, choosing a site within the reach of the Salt River that currently includes an artificial retention area called Tempe Town Lake. Since 1999 a two mile portion of the river channel has contained the reservoir for the purpose of recreation and development within the city of Tempe. As I investigated the viability of restoring an urban desert river to a more natural riparian condition, I developed a master plan that merges ecological river restoration with sustainable urban development. Research into the vegetative communities historically occurring along the river's edge guided me to create a project based in ecological principles. Expanding the concrete channel to a wider river presence followed examples set by case studies and the historic character of the Salt River. A new braided low flow channel, allowed to meander with the natural currents of the river, is terraced upwards in a gentle slope that maintains current 500-year flow plains. The vegetation communities I propose to establish along the new terraced elevations are adapted from Charles H. Lowe's profile of a foothill canyon and archival research specific to this portion of the Salt River. As a way to support the reintroduction of Arizona's lost riparian plant communities, the master plan incorporates the use of greywater and A/C condensate collection from proposed developments along the river's edge. These new water systems would be substantial enough to sustain riparian vegetation creation and in addition, provide for ground water recharge. Additional developments continue the City of Tempe's goal to expand development along the river and adjacent to the downtown core. Providing for increased recreational opportunity in a river setting improves the quality of life in Tempe and sets the community apart from surrounding desert cities. By applying ecological and sustainable design and planning principles, the Salt River Diaries master plan repairs the river's flow, restores the riparian vegetation, and redevelops the edge between the city and river.
ContributorsBruckner, Coby Ryan (Author) / Fish Ewan, Rebecca (Thesis director) / Cook, Edward (Committee member) / Sykes, Astrid (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / The Design School (Contributor)
Created2014-05
Description
Contrary to common thought at the end of the 20th century, the forces of globalization over the last several decades have contributed to more rigid rather than more permeable international borders as countries have enacted strict immigration and travel policies. This growing rigidity of international borders has paradoxically occurred as international tourism steadily grew up until the COVID-19 pandemic and conservationists adopted a landscape-scale approach to conserving and restoring ecosystems, often across international borders. Considering this paradox, this dissertation research examined the interactions between tourism development, ecological restoration, and bordering processes by utilizing bordering and stakeholder theories; core-periphery, cross-border tourism, and border frameworks; political ecology; and polycentric governance and cross-border collaboration literature. Together, these conceptualizations were used to assess stakeholder attitudes towards tourism development and ecological restoration, compare resource governance characteristics of private protected areas, and analyze shared appreciation for natural and cultural heritage at the U.S.-Mexico border. To collect data, the researcher utilized in-depth interviews, photo-elicitation interviews, focus groups, secondary data analysis, and observations to engage key tourism and conservation stakeholders from the region, such as tourism businesses, tourists, state and federal agencies, conservation nonprofits, ranchers, and residents The findings of this research revealed a political ecology of a border landscape that included social and environmental injustices and unequal stakeholder partnerships in tourism and ecological restoration initiatives. Unequal partnerships were also found in cross-border resource governance systems, largely due to the U.S. government’s border wall construction actions, and the necessity for government leadership in establishing vertical and horizontal linkages in polycentric governance structures was evident. The results also demonstrated how a shared appreciation for natural and cultural heritage contributes to debordering despite the rebordering actions of border security and strict travel policies. This study contributes to tourism literature by highlighting the need for tourism and ecological restoration initiatives to consider social and environmental justice issues, develop stronger cross-border linkages with governments and resource users, and foster cross-border collaboration and integration. This consideration of social and environmental justice issues involves sharing benefits of tourism and restoration, restoring and preserving resources that stakeholders value, and facilitating access to resources.
ContributorsClark, Connor (Author) / Nyaupane, Gyan P (Thesis advisor) / Timothy, Dallen (Committee member) / Budruk, Megha (Committee member) / Coronado, Irasema (Committee member) / Arizona State University (Publisher)
Created2022