Environmental Science
http://hdl.handle.net/10211.3/10211.4_34
2024-03-29T06:40:19ZModeling the risk for Phytophthora ramorum with an anthropogenic focus in northern California
http://hdl.handle.net/10211.3/211420
Modeling the risk for Phytophthora ramorum with an anthropogenic focus in northern California
Thornton, Alexandria S.
Phytophthora ramorum is an oomycete plant pathogen found in both North America and Europe that is commonly referred to as Sudden Oak Death (SOD). Since its initial detection in California in 1995, SOD has killed over a million trees, primarily tanoaks (Lithocarpus densiflorus), coast live oak (Quercus agrifolia), California black oak (Quercus kellogii), and Shreve’s oak (Quercus parvula var. shrevei). Northeastern California has thus far remained uninfected with the exception of one Rhododendron tree in Placer County. In order to contribute to the prevention of SOD spread to northeastern California, I created several models that depict where the risk for SOD development is highest based on four variables: host vegetation, climate suitability, proximity to roadways, and proximity to nurseries and lumber mills. I used a weighted overlay analysis to combine these variables at differing weights under five conditions. I applied the same analyses in Mendocino County, where sampling for SOD has resulted in 73 positive cases and 326 negative cases, to assess the accuracy of each condition. I calculated Cohen’s Kappa coefficient to measure the agreement between each condition and the recorded points. Though the Kappa values do not show strong agreement in the conditions, they do illustrate a trend of increase in agreement with the addition of proximity to roadways and nurseries. Suitable climate and host vegetation for SOD also exist along the coastal Pacific Northwest, and most of that area lies too far away from SOD incidence for natural spread to be the primary concern. Similar risk models incorporating human introduction variables could be applied to all of this area.
2019-07-08T00:00:00ZUsing LiDAR, ArcGIS, and on-the-ground data collection to describe geomorphometric characteristics of hydraulic mining features in the Yuba River watershed
http://hdl.handle.net/10211.3/208811
Using LiDAR, ArcGIS, and on-the-ground data collection to describe geomorphometric characteristics of hydraulic mining features in the Yuba River watershed
Ertis, Brandon
Hydraulic mining, a method of mining placer gold in alluvial deposits invented in California in 1853 and practiced for approximately a century afterwards, had and continues to have effects on sediment processes and water resources in northern California. This study focuses on three subwatersheds (Willow Creek, Oregon Creek, and Scotchman Creek) within the Yuba River basin, the most heavily hydraulically-mined watershed in the Sierra Nevada.
Prior work related to hydraulic mining in the study area was reviewed, resulting in a total of 35 previously identified hydraulic mining features (HMFs) being included in this study. These incorporate both locations where hydraulic mining occurred and locations where sediment produced by hydraulic mining is currently held, either behind a debris control dam (DCD) or in a natural drainage channel along a waterway. For each of these HMFs, the initial objective of this study was to conduct (1) a geomorphometric characterization and assessment of current conditions of the HMFs, for which a total of 40 categories were determined. As part of the geomorphometric characterization, (2) methodologies for estimating sediment volume results using LiDAR and ArcGIS were developed. Using the inventory results, sediment volumes were determined for (3.a) the amount produced by hydraulic mining sites and (3.b) the amount still held in the study area in sediment deposits, and (3.c) the two amounts were compared to inform what proportion of sediment produced remained within the study areas in the Upper Yuba River basin. Finally, (3.d) additional inventory results are compared and contrasted to better understand these HMFs and their characteristics.
Although the number of hydraulic mines in each subwatershed was similar, the sediment volumes produced by hydraulic mining varied greatly (~20 million m3 for Willow Creek, ~2 million m3 for Oregon Creek, and ~42 million m3 for Scotchman Creek). Known sediment deposit volumes comprised only a fraction of the volume produced by hydraulic mining (~0.6 million m3 for Willow Creek, ~0.4 million m3 for Oregon Creek, and ~0.4 million m3 for Scotchman Creek). A comparison of these volumes resulted in sediment delivery ratios of approximately 0.97 for Willow Creek, 0.83 for Oregon Creek, and 0.98 for Scotchman Creek. This shows that a majority of sediment produced has either been transported out of the subwatershed areas or is stored in locations other than the large deposits (primarily held behind DCDs) assessed in this study, or likely some combination of both. Though they only contain a fraction of the sediment produced from hydraulic mining sites, the sediment deposits need to be further studied and better understood, and additional sediment storage within these subwatersheds should be investigated. The numbers presented above should be considered an initial conservative estimate. There are likely additional HMFs (both mines and deposits) requiring identification and assessment. As a first step towards this, Potential HMF (P-HMF) Mines were identified from the LiDAR dataset based on similarities in appearance to previously identified HMFs. Four of these were visited in person and evidence was found indicating that they may represent additional locations where mining occurred within the study areas, although further investigation would be required to confirm this. There are also additional P-HMF Deposits that were identified, and there is likely HMS scattered throughout the study area in streambanks, high terraces, and other locations apart from the concentrated deposits focused on in this study. Finally, on-the-ground field work determined that sediment transport from HMFs is continuing, and no HMFs were visited that were hydrologically isolated from nearby waterways. Quantitative data about water quality and sediment transport would be valuable.
In summary, using airborne LiDAR dataset with a geospatial software program such as ArcGIS has proven to be an effective method of both evaluating HMFs and their impacts on watersheds, and identifying P-HMFs for future study and evaluation. However, on-the-ground research is needed as well to both verify and expand on results obtained from the LiDAR dataset
2019-03-19T00:00:00ZWet meadow vegetation community along a hydrologic gradient after passive restoration, Southen Cascades, CA
http://hdl.handle.net/10211.3/205886
Wet meadow vegetation community along a hydrologic gradient after passive restoration, Southen Cascades, CA
LaGrange, Allen L.
I examined the vegetation community and structure of a wet meadow from 2013-2017 across ecological, temporal and spatial scales, immediately following hydrologic restoration. I set out to determine if the natural seedbank can act as a primary source for passive revegetation. I collected soils from 20 vegetation plots across a hydrologic gradient and germinated potential seeds in a greenhouse. Obligate (OBL) and facultative wetland (FACW) seedbank species germinated in all plots along the hydrologic gradient. I compared seedbank composition with emergent vegetation using Sorensen’s similarity index and found a higher similarity with OBL and FACW species (35-55%) than with facultative upland (FACU) and upland (UPL) species (17-29%) across all years. Annual vegetation surveys demonstrated that FACU species cover decreased gradually in drier plots by 2017, whereas the wettest plots were dominated exclusively by OBL and FACW species across all years. FACW species cover increased in plots between the hydrologic extremes, while UPL and facultative (FAC) species cover decreased. The regeneration of OBL and FACW species was not constrained to only seed-producing species. The relative frequency of rhizomatous species Carex simulata and Juncus balticus remained stable throughout 2013-2017, and both species were able to propagate across a wide-range of hydrologic conditions. Vegetation community composition was driven predominantly by depth to water (r2 = 0.444), soil moisture (r2 = 0.231), organic matter (r2 = 0.408), and organic carbon (r2 = 0.414). These results provide evidence that passive revegetation can be a successful strategy after hydrologic restoration.
2018-08-29T00:00:00ZDeveloping a high-level greenhouse gas emissions inventorying protocol for local government climate action management: Chico, CA - a case study
http://hdl.handle.net/10211.3/200192
Developing a high-level greenhouse gas emissions inventorying protocol for local government climate action management: Chico, CA - a case study
Alexander, Fletcher
Over the past 10-12 years thousands of cities and counties across the United States have developed local Climate Action Plans to mitigate some degree of greenhouse gas emissions generated within their jurisdictions; hundreds of these cities are located in the state of California. The process of developing a Climate Action Plan usually involves the completion of a greenhouse gas emissions inventory in order to establish a baseline estimate of greenhouse gas emissions generated by those activities the local government plans to begin tracking and managing. Climate Action Plans generally have 10, 20 or 30-year horizons and a series of interim targets tiered off of an ultimate reduction target. Tracking progress of implementation over time requires regular accounting of emissions generated by activities within the plan’s scope. Completing city- or county-wide greenhouse gas emissions inventories can be a time- and resource-consumptive process, one that the planning departments often tasked with managing implementation aren’t necessarily equipped to conduct on an annual or biennial basis.
This project aims to develop a high-level community-wide greenhouse gas emissions inventorying protocol that can be utilized by these agencies and their staff on a regular basis to track progress on and guide resource allocation in Climate Action Plan implementation. The protocol focuses on the largest emissions generating activities within a jurisdiction, tracking data related to these activities at a high-level of aggregation. The protocol was developed to produce results that are relevant, accurate, complete, measurable, consistent and transparent. As a case study, the project quantifies an estimate of 11 years’ worth of community-wide greenhouse gas emissions for the City of Chico, CA. The City of Chico was an early signatory to the U.S. Conference of Mayors’ Climate Protection Agreement in 2006 and adopted a community-wide Climate Action Plan in 2012.
2018-02-21T00:00:00Z