Recipient Organization
UNIV OF MARYLAND
(N/A)
COLLEGE PARK,MD 20742
Performing Department
Environmental Science and Technology
Non Technical Summary
There is interest among researchers and managers to determine the potential for an expanded urban tree canopy to function as a pollution control best management practice in the Chesapeake Bay Watershed. This potential remains poorly characterized and a lack offieldstudies in urban forests hampers management decisions. This project uses a set of studies in urban forest patches in Baltimore City and urban tree settings in Montgomery County to characterize soil biogeochemistry and nutrient cycling dynamics. This research leverages existing research sites that are used to characterize urban hydrology. Soil nutrient pools and leachate solution, as well as physical, ecological, and management drivers of nutrient dynamics will be measured in 21 urban forest patches and along a management/landscape context gradient. These data will characterize how urban forest nutrient cycling is driven by several key environmental and management factors. This research will support future studies that will assess the dynamics and drivers of nutrient load reductions by urban tree canopy in the Chesapeake Bay Watershed.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
1. Assess the potential for urban forests to retain N and P2. Assess the drivers of urban forest nutrient cycling that are relevant for nutrient retention and load reduction, with respect to: a. Environmental drivers such as: temperature and soil moisture b. Site characteristics such as: plant cover, diversity, soils, invasive speciesc. Management context - small and large closed canopy forest, landscaped settings with isolated trees over turfgrass,3. Establish the potential for existing research sites to study urban tree cover contributions to nutrient load reductions for Chesapeake Bay health
Project Methods
Two different sets of study sites that allow different comparisons:A set of 22 forest patches in Baltimore City that will allow analysis of the influence of plant diversity, soil characteristics, invasive species, and management on nutrient dynamics, andA set of sites that represent three locations along an urban forest typology that spans from single, isolated street trees to closed canopy forest patches, that will allow analysis of the influence of tree cover on nutrient dynamics.Field Samples and Analysis(1) Standing litter cover and C:N content - standing litter mass will be sampled at 4 random locations at each patch and plot, grab samples will be collected, returned to the lab and weighed, then dried and analyzed for total C and N content.(2) Soil nutrient pools - Soil samples will be collected in Fall 2018, Spring 2019, and Summer 2019. At 4 random locations in each forest patch and typology setting, soil cores will be collected at 0-5 and 5-15 cm depths. Soil samples will be analyzed for:Total % C and NSoil Organic MatterConcentrations of NO3, NH4, and PO4(3) Soil nutrient dynamics: Tension lysimeters will be used to collect soil pore water and to give a proxy for dissolved nutrients leaching through the soil profile. Three tension lysimeters will be installed in each forest patch &/or location along the typology. Solution will be collected monthly and analyzed for NO3, NH4, and PO4. Bi-weekly measurement of in situ soil respiration will be made with a PP-systems infrared gas analyzer to assess CO2 efflux as an index of soil microbial activity.(4) Environmental Drivers:Canopy cover and shading of incoming radiation with hemispherical photography and Dynamax Hemi-view software.Soil Temperature with ibutton data loggersSoil Moisture - bi-weekly measurement of soil moisture contents with Hydrosense soil moisture probe (to 12 cm depth).Existing data on patch size, species composition, invasive species, soil texture, bulk density, and management will also be used to explain variability in soil nutrient pools and processes.Data Analysis - I will explore how urban forests and tree cover influence nutrient turnover and retention through multivariate analysis of the pool and transformation/fluxes data. Additionally, multiple regression analyses will be used to explore (1) the effects of species composition, litter chemistry, and invasive species (over and understory) on soil C:N ratios, nutrient pools, and soil solution leachate, (2) how the physical drivers of canopy cover and shade influence nutrient dynamics through soil moisture content, and (3) how patch characteristics and management and landscape contexts influence potential nutrient retention at the sites.