Soils represent an important terrestrial carbon (C) sink, storing up to three times the amount of atmospheric C, however climate and land use changes may transform soils into C sources. River corridor (RC) soils and associated C are at risk to become mobilized by erosion such as bank failure and scour events. Once soil-derived organic C is transferred into the stream, microbial processes and photodegradation of the dissolved, labile (or bioavailable) fractions can lead to the production of CO2, which can evade and increase atmospheric CO2 levels. Because predicted increases in heavy precipitation will likely increase this type of riverine erosion, it is important to better understand the potential for the release of bioavailable C from RCs. One objective of this thesis was therefore to identify and characterize representative samples of soils from a typical Vermont RC for common land covers and simulate the production of dissolved organic matter (DOM) during riverine soil erosion. Field sites representative of typical agricultural and forested land uses were selected based on the analysis of 106 existing samples and resampled multiple times over the summer of 2015. Production of DOM from riverine erosion was simulated using aqueous soil extracts (ASE), where soil and water were shaken at fixed ratios followed by the separation of the extract. To study the characteristics of these extracts (which serve as analogue of stream water after erosion), water extractable C (WEOC) concentrations, water extractable nitrogen, fluorescence properties of DOM, and bioavailability were determined. Results indicated a common, dominantly terrestrial source material for all land covers, but C concentrations and fluorescence properties differed. High but variable amounts of soil organic C and WEOC were observed in agricultural riparian and agricultural stream bank samples, and lower concentrations in agricultural field, forest, forest riparian, and forest stream banks. WEOC bioavailability was high in all agricultural land covers and low in forested land covers. Because this study is the first in which ASE are used as analogues for stream water after riverine erosion, a second objective was to test laboratory methods used in this study for their effect on WEOC, fluorescence properties, and bioavailability. Specifically, the effects of soil drying, soil storage, and the effects of the extraction solution were tested. For this, ASE were prepared from soils that were field moist, dried, and after two years of storage. In addition, dried soils were extracted using different solutions including a salt solution, river water, and double deionized (DDI) water. Results indicated WEOC concentration and microbial humic-like fluorescence from extracts of dried soils were higher than those in extracts of field moist soils, while WEOC concentration and microbial humic-like fluorescence was highest in extracts of soils stored long term. In addition, the bioavailability of WEOC was higher in dried soils than field moist soils. The extraction solutions of DDI water and river water produced DOM with similar fluorescence properties, while the salt solution extracted a different, less humified pool of C. Overall, the ASE methods used in this study are effective in simulating stream bank erosion and subsequent C release into stream water, however the effects of drying the soils need to be considered when assessing DOM.

The state of Vermont faces increasing risk of costly damage from catastrophic flooding events as climate change increases the frequency of heavy rains and cumulative precipitation. In addition to increasing flood inundation risk, extreme precipitation events are leading to high rates damage from fluvial erosion—erosion caused by the force of floodwater and the materials it carries. As in all U.S. states, flood hazard governance in Vermont is shared by multiple levels of government and involves a complex compliance model that relies on local governments to regulate private property owners to achieve community, state, or federal goals. To encourage municipalities to adopt higher-standard flood regulations, the State government created higher-standard model flood hazard bylaws and has incentivized their adoption through the State Emergency Relief and Assistance Fund program. The higher standards modeled by the State apply no-fill, no-build, and an assortment of additional standards that exceed the Federal Emergency Management Association’s National Flood Insurance Program’s minimum standards. The State encourages the application of higher standards not only to the federally mapped flood hazard area but also to the State-mapped “river corridor.” Though these regulations are enforced through the local flood hazard permitting process, State floodplain managers are meant to play a substantial advisory role in their regulation. A decade after the first of these flood hazard regulations appeared in Vermont municipalities, little is known about how much encroachment still happens in flood hazard areas and how municipalities have handled permitting projects under these new controls. A better understanding of the local governance of flood hazard regulations can further inform State flood hazard governance. This study of twelve Vermont towns found in those towns a fairly high degree of conformance to local regulations but a mixed record on compliance with the State’s expectations for the permitting process. There was on average a little under one investment per town over a 4.3-year period that was significant enough to, by law, trigger a conditional permit review. Within the study sample, activity in the regulated flood hazard zone conformed to local bylaws at a rate of about 88%. However, only three of the ten projects that triggered conditional review were reviewed at the State level, as is the expectation for new, replacement, or improved structures, and the fact that none of the suspected non-conforming structures received a State-level review (and some missed local review) suggests that receiving full review will increase the rate of individual permit conformance. Interviews with State officials indicated that the State may be more interested in changing the culture of local flood hazard mitigation than in achieving perfect land use conformance. When local actions that promote access to information and the capacity to regulate are compared with a Town’s permitting compliance rate, a slight pattern emerges showing that communities that have flood regulation information available online, town-wide zoning, and a zoning administrator, are more likely to have projects be permitted by the Town and sent to the State for review. Interviews with State-employed flood managers and local floodplain administrators also suggest that additional social factors, such as whether bylaws have community “champions” and who acts as the zoning administrator, may influence the degree of community compliance. Often local authorities rely on their own discretion to regulate activity in the flood hazard area as a way of navigating tensions between regulations and private property rights, representing both a valuable point of flexibility for compliance and a potential sticking point in the State’s effort to facilitate a culture shift. Flood hazard mitigation regulation in Vermont most closely aligns with a cooperative enforcement model, which relies on long-term relationships and credible threat of enforcement (among other factors) in order to work. Because the findings show that breakdowns in the expected relationship between Town and State government clearly occur, one important approach to achieving a cultural shift would appear to be strengthening State-local relationships. This may involve increasing the State staff-to-community ratio, conducting more community visits and trainings, distributing a flood regulations enforcement manual, strengthening the capacity of regional planning agencies, and/or reducing the barriers to preparing permits for State review. Focusing on long-term relationship-building with a number of community members may help prevent the breakdown in communication that can occur as individual floodplain administrators come and go. A second strategy would continue to support the state-wide housing buyout program to mitigate inequitable outcomes and general resentment over property loss. And because the ERAF incentive program does not have any penalties that incentivize enforcement, a third beneficial approach would involve creating stronger incentives for local enforcement and compliance, such as ERAF criteria that mandates local enforcement actions and improved State-level monitoring of compliance. Yet while there may be room for strengthening flood hazard regulation enforcement, Vermont’s innovative regulations and incentives for adoption appear to be translating fairly well into local-level conformance and compliance, and could serve a model for other states.

Many plant species are closely related to river biotopes or to biotopes influenced by rivers. River systems create important linear corridors in ecosystems and directly or non-directly influence spatial spread of species in these environments. This offer many questions about species spread in this system. We can answer these questions by using molecular methods. Using 10 microsatellite (SSRs) primers, 202 individuals of Phragmites australis from 60 populations were analysed. Those analyses allowed reveal kinship of individuals, obtain information about spatial spread of populations and about spreading of common reed. Phragmites australis creates both - monoclonal and polyclonal - populations. Dependence of rate of clonality on environment was revealed. Populations from river banks are more monoclonal, populations from pond shores are more polyclonal. Populations are isolated. The highest percentage of variability was explained on among-population level. This is common for anemochoric species. Communication between populations is present, more on shorter distances. Evidence for vegetative spread was found on short distance. Generative spread is much more common. Long-distance spreading is mediated by generative diaspores - seeds. This spreading includes within-river spread, among-river spread and spreading...