Current Search:   Chambers, Lisa (x)

View All Items

  • CSV Spreadsheet
(1 - 4 of 4)
Characterizing biogeochemical shifts in two Salix Caroliniana Michx. encroached freshwater subtropical marshes
Title
Characterizing biogeochemical shifts in two Salix Caroliniana Michx. encroached freshwater subtropical marshes.
Creator
Ho, Janet, Chambers, Lisa, Hinkle, Ross, Savage, Anna, University of Central Florida
Abstract / Description
Shrub encroachment is a common disturbance in wetlands, but little is known about how shrub encroachment impacts functions such as carbon (C) storage and nitrogen (N) cycling. The objective of this thesis was to identify differences in physiochemical properties (within soil, water and leaf tissue) and biogeochemical processes (soil respiration, enzyme activity, litter decomposition, and N cycling) in two subtropical freshwater marshes encroached by coastal plain willow (Salix caroliniana...
Show moreShrub encroachment is a common disturbance in wetlands, but little is known about how shrub encroachment impacts functions such as carbon (C) storage and nitrogen (N) cycling. The objective of this thesis was to identify differences in physiochemical properties (within soil, water and leaf tissue) and biogeochemical processes (soil respiration, enzyme activity, litter decomposition, and N cycling) in two subtropical freshwater marshes encroached by coastal plain willow (Salix caroliniana Michx.). Two study regions (Moccasin Island and Lake Apopka) were selected because of their location in the St. John's River watershed and their unique histories and hydroperiod, allowing for an investigation of how synonymous the effects of willow-encroachment are across sites. A stratified random sampling design was employed in each region, identifying three plot types: willow ((>)80 % willow aboveground coverage), adjacent marsh ((>)80% herbaceous aboveground coverage and (<)1 m from willows), and control marsh ((>)80% herbaceous aboveground coverage and (>)10 m from willows) plots. Triplicate soil samples were collected in each plot in the wet and dry seasons of 2017 and analyzed for physiochemical properties (bulk density, moisture, nutrient content) and used in laboratory assays to measure soil respiration, enzyme activity, and potential N mineralization and denitrification rates. Leaf tissue was collected from the dominant vegetation in each plot and analyzed for nutrient content (total C, lignin-C, and total N). Short-term litter decay rate was determined using a litter-bag field experiment. Bioavailable N and dissolved organic C (DOC) concentrations were determined from surface and porewater collected from the center of each plot. In Moccasin Island, lower decomposition rates and greater denitrification, potential N mineralization, and soil C and N content were detected in willow and adjacent marsh plots, suggesting greater C storage and N cycling in willow-encroached marshes compared to non-encroached control marshes in Moccasin Island. Conversely, soil C and N content was lowest in willow plots in Lake Apopka. Decomposition and microbial activity (enzyme activity and respiration) were lowest in willow dominated areas and correlated to soil nutrient concentrations. In both regions, microbial compositional changes (gene copy number) were detected between plot types, mainly in bacteria (?-proteobacteria and Bacteroidetes) for Moccasin Island and archaea and fungi abundance in Lake Apopka. Ultimately, willow plots in both regions had greater lignin-C content and short-term litter C storage. Greater bioavailable N was also observed in adjacent and/or willow plots in both regions. However, soil C storage and N cycling differences were not synonymous between the two regions. Future studies of willow effects will need to look at multiple sites or risk making inaccurate generalizations. From the findings from this study, wetland processes can be altered in willow-encroached marshes and this data can help land managers decide where to allocate resources based on valued ecosystem services.
Show less
Date Issued
2018
Identifier
CFE0007015, ucf:52043
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007015
Mucking About: Hydrologic Regime and Soil Carbon Storage in Restored Subtropical Wetlands
Title
Mucking About: Hydrologic Regime and Soil Carbon Storage in Restored Subtropical Wetlands.
Creator
Huber, Alicia, Bohlen, Patrick, Hinkle, Ross, Chambers, Lisa, University of Central Florida
Abstract / Description
Wetlands are extremely important ecosystems that have declined drastically worldwide, continue to be lost, and are threatened globally. They perform a number of important ecosystem services such as flood control, provide habitat for many species, and have aesthetic and recreational value. Wetlands are also important to the global carbon (C) cycle. Wetland soils are especially effective C sinks because they have high primary productivity and low decomposition rates due to flooded, anoxic...
Show moreWetlands are extremely important ecosystems that have declined drastically worldwide, continue to be lost, and are threatened globally. They perform a number of important ecosystem services such as flood control, provide habitat for many species, and have aesthetic and recreational value. Wetlands are also important to the global carbon (C) cycle. Wetland soils are especially effective C sinks because they have high primary productivity and low decomposition rates due to flooded, anoxic conditions. Increased recognition of wetlands' value has led to more ecological and hydrological restoration of degraded wetlands to mitigate the effects of wetland destruction. Hydrological restoration, which attempts to recreate natural hydroperiod and water levels in wetlands, is expected to increase soil C storage. Many studies have estimated the C stock in different wetland ecosystems across biomes, but few have examined hydrological drivers of soil C variation across wetland types. This study investigated the relationship between hydrologic variables (hydroperiod and average water depth) and soil C storage in three types of hydrologically restored wetlands (marsh, bay swamp, and cypress swamp) at the Disney Wilderness Preserve (DWP) in central Florida, USA. I collected 150 50-cm soil cores along existing monitoring transects in sampled wetlands where water elevation data had been collected since 1995 to examine the relationship between hydrologic variable and soil C storage. I analyzed a combination of generalized linear mixed models (glmm), evaluated using AICc. Mean water depth was a better predictor than hydroperiod of soil C concentration and stock. Mean water depth had a significant positive relationship with soil C concentration in bay swamps and marshes and soil C stock in marshes. However, this effect was small and often outweighed by other factors such as differences in vegetative community, soil depth, or local site conditions. Water depth had no significant relationship with soil C concentration in cypress swamps or upland communities or on soil C stock in bay swamps, cypress swamps, or uplands. Wetland community type had a strong influence on soil C variation, with bay swamp soils having the highest mean soil C concentration followed by cypress swamp, marsh, and upland soils, respectively. Soil C concentration generally decreased with soil depth. Bay swamps also had the highest soil C stock, followed by cypress swamp, marsh, and upland soils, respectively. Together, the sampled wetland communities cover approximately 22% of the sampled communities at DWP, yet store an estimated 47% of the total soil C to a 90 cm depth. The results of this study affirm the importance of inundation for soil C storage in wetlands, but also highlight that there are a number of other complex variables affecting soil C in different types of wetlands such as differences in litter quality and decomposition rates.
Show less
Date Issued
2017
Identifier
CFE0007122, ucf:51930
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007122
Understanding sediment biogeochemistry and the role of juvenile oysters on recently restored eastern oyster reefs
Title
Understanding sediment biogeochemistry and the role of juvenile oysters on recently restored eastern oyster reefs.
Creator
Locher, Bryan, Chambers, Lisa, Walters, Linda, Kibler, Kelly, University of Central Florida
Abstract / Description
In recent decades, goals for the restoration of eastern oyster (Crassostrea virginica) populations along the eastern coast of the United States have shifted from increasing harvestable oyster fisheries to enhancing the range of ecosystem services provided by oyster reefs. By filtering large volumes of water and releasing nutrient-rich feces and pseudofeces, oysters can locally enhance sediment biogeochemical cycling compared to that of unstructured benthic environments. An ongoing restoration...
Show moreIn recent decades, goals for the restoration of eastern oyster (Crassostrea virginica) populations along the eastern coast of the United States have shifted from increasing harvestable oyster fisheries to enhancing the range of ecosystem services provided by oyster reefs. By filtering large volumes of water and releasing nutrient-rich feces and pseudofeces, oysters can locally enhance sediment biogeochemical cycling compared to that of unstructured benthic environments. An ongoing restoration program in Mosquito Lagoon, FL was leveraged to assess the immediate impacts ((<) 1 year) of restoration on sediment biogeochemical properties of oyster reefs. The first study measured both short-term and long-term pools of carbon, nitrogen and phosphorus on dead, natural and restored reefs periodically over one year. The second study investigated one of the contributions to sediment nutrient pools by comparing feeding and feces/pseudofeces nutrient content of juvenile and older oysters. Results show that inorganic nitrogen and phosphorus pools can change within weeks after restoration and total nutrient pools by 6 months post-restoration. Restored reefs experienced a 136 % increase in ammonium, 78 % increase in total nitrogen, 46 % increase in total phosphorus, and 75 % increase in organic matter concentrations after 12 months of restoration. These nutrient increases were all positively correlated with oyster density, shell length and reef height measured on each reef. When standardized to grams of dry tissue weight, juvenile oysters showed significantly higher rates of chlorophyll-a removal, release of ammonium, and biodeposits with higher concentrations of dissolved organic carbon, nitrite + nitrate, and ammonium. The short-term changes to biogeochemical cycling on eastern oyster reefs within the first year of restoration are important to managers seeking to monitor ecosystem service recovery and overall coastal ecosystem health.
Show less
Date Issued
2019
Identifier
CFE0007671, ucf:52460
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007671
Biogeochemical effects of sea level rise-induced transitions within coastal wetlands
Title
Biogeochemical effects of sea level rise-induced transitions within coastal wetlands.
Creator
Steinmuller, Havalend, Chambers, Lisa, Hinkle, Ross, Bohlen, Patrick, Beazley, Melanie, University of Central Florida
Abstract / Description
As sea level rise (SLR) affects coastal wetlands, ecosystem responses can include vertical accretion, landward transgression, or submergence. Sea level rise-induced transitions can alter key biogeochemical transformations within wetland soils, impacting the ability of these systems to provide ecosystem services, specifically carbon (C) storage and water quality regulation. Through a series of complementary laboratory and field-based studies, biogeochemical responses to salinity, vegetation...
Show moreAs sea level rise (SLR) affects coastal wetlands, ecosystem responses can include vertical accretion, landward transgression, or submergence. Sea level rise-induced transitions can alter key biogeochemical transformations within wetland soils, impacting the ability of these systems to provide ecosystem services, specifically carbon (C) storage and water quality regulation. Through a series of complementary laboratory and field-based studies, biogeochemical responses to salinity, vegetation shifts, and submergence were investigated. Changes in nutrient dynamics associated with saltwater intrusion were evaluated by artificially adding saline water to different freshwater wetland soil types, indicating that potential exports of critical nutrients (forms of nitrogen, phosphorus, and C) out of freshwater wetland soils is mediated by soil type. A controlled laboratory experiment was conducted to determine the potential degradability of C stored within submerging coastal wetland soils under both aerobic and anaerobic conditions. Under aerobic conditions, 66% more carbon dioxide was produced than under anaerobic conditions and 4x greater carbon dioxide was produced at 90-100cm depths than at the surface. At the same site, the degradability of carbon stores was examined through organic matter fractionation, stable isotopic examination, and determining the abundance of key microbial genes. Both total soil C and stores of bioavailable nutrients increased with depth, while organic matter quality decreased. Finally, the biogeochemical impacts of two separate vegetation transitions occurring co-incidentally with sea level rise were investigated: mangrove encroachment into salt marsh, and more salt- and inundation-tolerant herbaceous encroachment into herbaceous marsh. Conclusions from these studies demonstrate that vegetation transitions alter both soil nutrient storage and fast-cycling nutrient pools, indicating that biogeochemical transitions occur in advance of changes in vegetative species dominance. Results from these chapters holistically address how biogeochemical functioning, specifically nutrient cycling, regulation of water quality, and C sequestration, within coastal wetlands responds to stressors associated with SLR.
Show less
Date Issued
2019
Identifier
CFE0007536, ucf:52584
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007536