- ItemOpen AccessExperts vs. novices: a comparison of the quality and quantity of Bombus observations between citizen scientists and researchers in national parks(Colorado State University. Libraries, 2023) Smith, Alia, author; Bowser, Gillian, advisor; Halliwell, Philip, advisor; Balgopal, Meena, committee member; Newman, Gregory, committee memberCitizen science data is plentiful and diverse in its collection, storage, and subsequent application. Different platforms have unique methods of storing data and limitations in accessing the data contributed to the platform. This study explored the accessibility of citizen science data from several citizen science platforms and compared two different methods of collecting data from iNaturalist, a global citizen science platform for observing and identifying organisms. It focused on Bombus species observations made in Grand Teton and Yellowstone National Parks. The study found that different platforms are not equal in the ability to access and utilize data. It also found that on iNaturalist one method of searching for data yielded 14% more results than the other. The separate and incomplete nature of accessible data across citizen science platforms and subjectivity of searching methods on iNaturalist are indicative of the difficulty in creating a complete dataset that is representative of the collective contributions of citizen scientists. The validity of citizen science research has been controversial in recent history. There is a general consensus, however, that citizen science must be verifiable to be trustworthy. iNaturalist is a crowdsourced citizen science platform that allows other users to corroborate or dispute species identifications that individuals post. This research seeks to determine whether there is a difference in the quantity and quality of Bombus observations in Grand Teton and Yellowstone National Parks made by expert researchers and citizen scientists on iNaturalist. It found that the professional researchers, or experts, contributed 68% of the observations, but there was not a significant difference between the achievement rate of Research Grade observations between the experts and novices. This indicates that citizen scientists have the ability, through iNaturalist, to accurately make difficult taxonomic identifications.
- ItemOpen AccessPartnerships on Colorado conservation lands: social-ecological outcomes of collaborative grazing management(Colorado State University. Libraries, 2022) Monlezun, Anna Clare, author; Lynn, Stacy, advisor; Boone, Randall, committee member; Jones, Kelly, committee member; Rhoades, Ryan, committee memberTo view the abstract, please see the full text of the document.
- ItemOpen AccessStreamflow generation across an elevation gradient after the 2020 Cameron Peak Fire(Colorado State University. Libraries, 2022) Miller, Quinn, author; Kampf, Stephanie, advisor; Nelson, Peter, committee member; Hammond, John, committee memberThe western United States is experiencing an increase in catastrophic wildfire in virtually all ecoregions. Many of these fires burn in forested headwaters that communities rely on for water supply, underscoring the need for a greater understanding of how wildfire impacts streamflow timing and magnitude. Though many studies have examined the hydrologic response to fire, the site-specific nature of this type of research has made it difficult to generalize findings. The 2020 Cameron Peak fire burned across a broad swathe of the Colorado Front Range, making it an ideal case study to examine the factors that affect post-fire runoff. The goal of this work is to identify how streamflow responses to rainfall vary from pre-to post-fire conditions and between mountain regions defined by seasonal snow cover and aridity. To this end, we selected three watersheds to compare fire effects on rainfall runoff between snow zones. These watersheds were unburned, moderately burned, and severely burned in each of two snow zones: the high-elevation persistent snow zone, and the mid-elevation intermittent snow zone. These watersheds were instrumented to monitor rainfall and stream discharge throughout water year 2021. To evaluate how wildfire affected runoff, we developed multi-variate statistical models and used Tukey's Honestly Significant Differences test to compare streamflow responses to rainfall between watersheds. Across all burn categories, the high elevation sites were more responsive to rainfall compared to streams at lower elevations; ~50% of rain events produced a streamflow response in the persistent snow zone, compared to ~25% in the intermittent snow zone. In both snow zones, the unburned sites were the least responsive to summer rainfall and had the highest summer baseflows. Although the high elevation streams were more responsive to rain, they did not exhibit evidence of infiltration excess overland flow. Lags between peak rainfall and peak discharge were 1.2-31.3 hr at these sites; in contrast, the low elevation severely burned site had a much more rapid rise to peak discharge (0.6 hr on average) that indicated infiltration excess overland flow. The rainfall intensity threshold necessary for runoff generation at this site was 4 mm hr-1, which agreed with thresholds reported in similar studies of burned areas in this region. We found no evidence that the moderately burned site in the intermittent snow zone generated rapid runoff, likely because that watershed did not experience enough moderate to high burn severity to promote widespread overland flow. Additionally, the flow response at burned sites was uniformly shorter than for the unburned sites in both snow zones. The magnitude of the flow response was higher in the persistent snow zone than in the intermittent snow zone; however, the effect of burn status on streamflow magnitude was difficult to ascertain. These results demonstrate that the streamflow responses to fire vary between snow zones, indicating a need to account for elevation and snow persistence in post-fire risk assessments. Future work in other regions could evaluate whether this snow zone effect is unique to the study area or a common cause of differences in post-fire streamflow.
- ItemOpen AccessVariation in soil organic carbon across lowland tropical forest gradients: soil fertility and precipitation effects on soil carbon organic chemistry and age(Colorado State University. Libraries, 2022) Blackaby, Emily, author; Cusack, Daniela F., advisor; Boot, Claudia M., committee member; Cotrufo, M. Francesca, committee memberTropical forests hold large amounts of carbon (C) in both aboveground biomass and belowground soil organic carbon (SOC) stocks. Climate change is expected to alter tropical forests' precipitation with some forests already showing decreased rainfall. We analyzed SOC molecular composition and age in lowland tropical forests of Panama across fertility gradients, rainfall ranges, and soil order. We hypothesized that H1) rainforests with relatively greater rainfall store larger amounts of proteins (N-alkyl) and lipids (alkyl) in SOC because of greater microbial biomass and H2) subsurface SOC stocks in more strongly weathered, clay-rich soils are older (as indicated by radiocarbon) because of great sorption capacity. We found that overall, carbon decreased and became older with depth across all samples. Solid-state 13C NMR spectroscopy indicated that soil order and depth were significant predictors of C functional group abundances while phosphorus (P) was a significant predictor of alkyl, aromatic, and carboxyl C. Alkyl/O-Alkyl ratios increased with depth indicating increased degradation of the SOC. ∆14C values indicated older C with depth and varied significantly with soil order where Oxisols were the oldest and Mollisols the youngest. Soil N % and K % were significant predictors of younger soil C. Additionally, biomolecular composition of SOM from 0-10 cm was a significant predictor of ∆14C at 25-50 cm. We found that higher abundances of alkyl and O-alkyl C corresponded with younger C at depth and higher abundances of aromatic and phenolic C contained older C at depth.
- ItemOpen AccessMulti-decadal impacts of high-severity wildfire on ecosystem nitrogen cycling(Colorado State University. Libraries, 2022) Rhea, Allison Elizabeth, author; Covino, Tim, advisor; Rhoades, Charles, advisor; Kampf, Stephanie, committee member; Rathburn, Sara, committee memberWildfires modify the amount, form, and distribution of nitrogen (N) throughout an ecosystem. Though N stocks are lost during the combustion of vegetation and surface organic matter, there is often a subsequent increase in inorganic N delivery to streams that provide drinking water to the Western US. This can make streams and reservoirs more susceptible to eutrophication and algal blooms, threatening the delivery of clean drinking water. While many post-fire studies have documented short-term (<5 years) increases in soil and stream inorganic N, long-term monitoring after the Hayman fire has revealed that increases in stream N can persist for decades. This dissertation investigates the long-term controls of elevated post-fire N across spatial scales. Chapter 2 describes the stream biotic response to the Hayman and High Park fires that burned along the Colorado Front Range. I evaluated stream water chemistry, algal nutrient limitation, benthic biomass, and stream metabolism along stream reaches within three burned and three unburned watersheds. Although the two high-severity wildfires occurred five and 15 years prior to the study, the streams draining burned watersheds still had 23-times higher nitrate (NO3-) concentrations than unburned watersheds, a trend that is consistent across seasons and throughout the 15-year post-fire record. Autotrophic N-limitation was reduced in these nitrate-rich burned streams. Consequently, autotrophic biomass and primary productivity were 2.5 and 20-times greater, respectively, in burned relative to unburned streams which indicates post-fire increases in stream N demand. However, the continued export of N out of these burned streams suggests that terrestrial N supply exceeds in-stream N demand. This suggests that streams have a limited capacity to attenuate N exports from burned watersheds. It was unclear if terrestrial N delivery to streams was driven by long-term elevated soil inorganic N supply (i.e., pools and net transformation rates) or depressed post-fire vegetation recovery and plant nutrient demand. I address this knowledge gap in chapter 3, by measuring inorganic N in surface mineral soils (0-15 cm), soil leachate (30 cm), and shallow groundwater (40-100 cm) in unburned watersheds dominated by ponderosa pine (Pinus ponderosa) and shrub-dominated watersheds that burned 17 years prior in the 2002 Hayman fire. Wildfire caused large C and N losses from soil O horizon during combustion (~1,500 and 50 g /m2 of C and N, respectively). However, total C and N stocks, soil-extractable inorganic N, plant-available inorganic N, and net N transformation rates (i.e., nitrification, and N mineralization) differed little between burned and unburned mineral soils. This indicates that there were no long-term post-fire increases in soil N supply. In contrast to the near surface patterns, NO3- concentrations were four- and ten-times higher, respectively in shallow groundwater and streams of burned watersheds. Tree regeneration has been slower than expected following the Hayman and other fires in the western US and these biogeochemical patterns suggest that low plant N demand may prolong the impacts of wildfires on stream nutrients where more extreme fire behavior and climatic conditions inhibit vegetation recovery. Finally, in chapter 4, I investigated the landscape and stream network drivers of persistent elevated stream NO3- in nine watersheds that were burned to varying degrees by the Hayman fire. I evaluated the ability of multiple linear regression and spatial stream network modeling approaches to predict observed concentrations of the biologically active solute NO3- compared to the conservative solute sodium (Na+). No landscape variables were strong predictors of stream Na+. Rather, stream Na+ variability was largely attributed to flow-connected spatial autocorrelation, indicating that downstream hydrologic transport was the primary driver of spatially distributed Na+ concentrations. In contrast, vegetation cover, measured as mean normalized differenced water index (NDMI) was the strongest predictor of spatially distributed stream NO3- concentrations. Furthermore, stream NO3- had weak flow-connected spatial autocorrelation and exhibited high spatial variability. This pattern is likely the result of spatially heterogeneous wildfire behavior that leaves intact forest patches interspersed with high burn severity patches that are dominated by shrubs and grasses. Post-fire vegetation also interacts with watershed structure to influence stream NO3- patterns. For example, severely burned convergent hillslopes in headwaters positions were associated with the highest stream NO3- concentrations due to the high proportional influence of hillslope water in these locations. My findings help characterize the potential magnitude, duration, and location of water quality concerns following fire. Slow forest recovery in large, high severity burn patches will likely sustain post-fire N export by limiting vegetation N uptake. As regeneration failures become more common with increasing fire severity and climate aridity, ecosystems will be more susceptible to sustained NO3- losses. If reforestation is desired, targeted plantings in riparian corridors, severely burned convergent hillslopes, and headwater positions will likely have the largest impact on stream NO3- concentrations.