Completed Research Projects
Climate Change
The concept of the current experiment is to study carbon storage and possible cycling in soils which alternate between saturation and nonsaturated conditions on an annual basis. To allow the data to be considered robust, or applicable to numerous locations and soil types it will be necessary to have multiple years of data, but to also have data that 'repeats' or replicates itself. Statisticians contend that replicate study areas are required, but it may be that the soil environment is different enough from one place to another that the least variability within the data will come from multiple or replicate data stations within a single area.
The goals and objectives of the project are: To better understand the hydrological, biogeochemical and pedological properties and processes that affect SOM decomposition, CO2 and CH4 greenhouse gas fluxes, and C sequestration in depressional wetland ecosystems, as expressed across geographical and climatic gradients. I also hope to determine the relationship between soil and air temperature and accumulated soil C stocks and fluxes in depressional wetland systems, to determine the relationship between hydroperiod (i.e. duration of saturation and inundation) and accumulated soil C stocks and fluxes in depressional wetlands. Finally, I will seek to develop morphological indices of the hydroperiod within depressional wetlands in order to estimate or predict C
stocks.
Communities across the country are face challenges from climate change. However, changes in municipal regulations take years to significantly change the buildings and infrastructure that make up our cities and towns. As a result, it is essential that communities begin now to adapt their built form regulations so that as climate impacts worsen, harm is minimized. Outside of the major cities, it is not clear how many communities have taken steps toward climate change adaptation. There are a range of ways that communities could progress local adaptation policy, including preparing adaptation plans, including climate projections into other policy, or increasing resilience to current hazards and hoping that will help with intensified future risks. To explore these issues, this project will pilot a web-trawler that can identify adaptation actions at the local level in the New England region, and compare these to the situations of the communities. We will also survey Regional Planning Agencies and a sample of communities in the region. Taken together, this work will allow us to identify the status and types of adaptation actions underway in the region, the goals and barriers they are designed to address, and characterize these connections.
Three temperate forage grass species (Lolium perrene, Festuca arundinacea, and Dactylis glomerata) will be grown in 6x10 ft plots under field conditions over the summer at the University of Massachusetts Crop and Animal Research and Education Farm in South Deerfield, Massachusetts. Each species will be grown in 10 replicates for a total of 30 plots. Five replicates of eachs pecies will be treated as well-watered controls and their soil moisture maintained above 25%, while the other five replicates will remain under a water-reduced treatment, receiving no rain or supplemental water. Water reduction will be imposed through the use of rain-out shelters. The shelters will have sides that could roll up and down in order to maintain ambient temperature and allow maximum air flow through the plots on dry days, but will be rolled down on rainy days to keep the water out. Water-reduction conditions will last for 10 weeks, after which rain shelters will be removed and rewatering begins over a period of three weeks in order to stepwise return soil moisture content to above 25%.
Microbial community composition: Throughout the water reduction period, bacterial communities will be sampled once a week for a total of 10 samples and an additional three times during the recovery period. Several mature but not senescent leaves will be collected from each plot for DNA extraction and bacterial cell counts in order to capture a representative community of the whole plot. Samples will be prepared for 16S rRNA sequencing using the Illumina MiSeq platform in two separate pools. Plant health measurements: To understand how bacterial communities change in relation to changes in the plant, several plant health measurements will be taken. Leaf relative water content, electrolyte leakage, chlorophyll, and soil moisture will be measured every week. Additionally, non-destructive biomass measurements will be taken periodically by measuring leaf height and plot coverage. Plot coverage will be estimated using an elevated quadrat device. At the end of the water reduction period, plots will be divided in half and destructive biomass sampling of one half will provide above ground fresh weight and dry weight measurements. Additionally, roots will be sampled in 15 cm increments to a depth of 60 cm. After soil removal roots will be dried and dry mass measured.
Nitrogen fixation rates by leaf microbes: Samples will be collected during field studies in the summer and used to quantify potential and actualized nitrogen fixation in the phyllosphere. Additional questions will be focused on understanding how phyllosphere BNF is impacted by plant host species, temporal dynamics, drought, and recovery. To determine the rate of BNF,stable isotope probing will be conducted at 6 different time points. Three samples will be taken during the drought period (week6, 7, 10) and three each week during recovery. Rate of nitrogen fixation will be determined by measuring incorporation of thestable isotope 15N into the leaf tissue. Leaf cuts of known area will be incubated in an artificial atmosphere containing 80% 15N and 20% O2 for 48 hours under ambient light and temperature. Corresponding control samples will be incubated under normal atmosphere to determine natural 15N abundance. After incubation, samples will be dried at 70°C, weighed, finely ground, and 1-2 mg of plant powder will be weighed in tin capsules and sent to a collaborator at the University of Vienna to determine 15N incorporation using a continuous-flow isotope ratio mass spectrometer. Nitrogen fixation rates can then be determined using the following equation where Nleaf is foliar N concentration, Mr is molecular weight of 15N, and t is incubation time:N2-Fix = Nleaf x (at%15Nsample - at%15Ncontrol)/100 x 103/Mr/tBacterial DNA samples corresponding to each timepoint will be taken to determine the absolute abundance of nitrogen fixing bacteria at each time point as well as to determine their taxonomic identity. The absolute quantity of nitrogen fixing bacteria per leaf area for each of the grass species and treatments will also be determined for the same time points using qPCR of the nifH gene. Next, the rate of nitrogen fixation per nifH copy number will be determined for each grass species under normal and water-stressed conditions. By comparing the three grass host species we will gain a better understanding of how phyllosphere BNF inputs are impacted by plant host species. By directly comparing rates under normal and stressed conditions we will understand how BNF will be influenced in the future by climate stress. Identification of nitrogen fixing members of the bacterial community will be achieved by sequencing the phylogenetic marker genes nifH using the Illumia MiSeq platform. nifH identity,diversity, and richness will be added to the models to better understand biological nitrogen fixation in the phyllosphere.
Global climate change affects every aspect of our life. Global warming increases the intensity of drought, which leads to the increase in frequency and severity of forest fires. Beyond being a source of soot and polyaromatic hydrocarbons (PAHs), severe wildfires/forest fires can damage soils, water quality and quantity, fisheries, plant communities, wildlife habitat, and endangered species; result in economic and property loss; and cause harms to the environment and public health. Forest thinning or prescribed burns reduce the accumulation of hazardous fuels and restore forest health. The major cause of global warming is the ever-increasing concentration of carbon dioxide (CO2) in the atmosphere from the use of carbon-based fuels. Biochar, the anaerobic pyrolysis productof biomass waste material, has attracted research interest as a soil amendment that may improve soil structure, moisture retention, and buffering capacity, and that helps control plant root diseases and sequester carbon in soils (instead of release to air as CO2), as a result, mitigate greenhouse effect. Therefore, the goal of this proposed project is to utilize wood waste materials to produce biochar which can be used in both forest and agricultural soils to improve soil quality, sequester carbon in soils, and reduce the emission of greenhouse gases (e.g., CO2 and N2O).
