Development of landscape variables to inform models of meadow vulnerabilities and adaptation under changing climate

Numerous studies suggest that the response of individual meadows to changing hydrology associated with climate and/or management activities depends on the hydrogeomorphology of the meadow and the landscape setting. Local geology can influence the relative timing and amount of groundwater and surface water inputs into montane wetlands. For example, the permeability structure of hillslope materials (e.g. glacial till vs. talus) can affect the timing and amount of shallow groundwater discharged to downstream wetlands. Permeable fractured volcanic and/or metamorphic rocks (typical of the Cascades) can transmit and store more water than impermeable crystalline intrusive rocks (typical of the Sierras), resulting in differential long-term responses to climate change. Although the influence of these hydrogeomorphic controls on meadow responses to changing hydrology are well documented at local scales, the influence of these controls – and the degree to which existing spatial datasets sufficiently capture important variation in these controls – is not well-documented at landscape to regional scales for Sierra Nevada meadows.

The project will use a 26-year time series (1985-present) of climate and remotely sensed data in ~8,100+ meadows to analyze meadow vegetation responses (i.e., their sensitivity) to contemporary variation in climate. The principal research goal is to characterize how these responses vary in accordance with hydrogeomorphic contexts (e.g., geology, elevation, topographic position, soils, basin hypsometry, etc.) at an ecoregional scale. The resultant information will be used to develop a spatially-explicit vulnerability assessment of Sierra Nevada meadows based on our meadow sensitivity results, projections of climate variables that meadows are sensitive to (exposure) and indicators of adaptive capacity (e.g., geomorphic context, connectivity, intactness, etc.). A decision framework will be developed that provides guidance on where to focus restoration and conservation actions based on meadow vulnerability assessment results. This framework can then be incorporated into existing meadow prioritizations to allow practitioners to more rigorously consider climate impacts and adaptation options.

USGS Nevada Water Science Center is providing the following landscape variables derived from existing data (digital elevation maps, geologic maps, landforms, vegetation) and field visits for the meadows of interest as identified by the USFS:

1. Watershed characteristics that may influence the timing and amount of precipitation (e.g. basin hypsometry, contributing area, watershed aspect, topographic position index).
    
2. Ecologically relevant landforms from Theobald et al 2015.
    
3. Fire Return Interval Departure from Safford and Van de Water 2014.
    
4. Geologic characteristics that indicate the potential importance of the groundwater system (e.g. rock type and proximity to potential montane aquifers such as glacial deposits and highly fractured rock).

Additional information about the decision support framework, which uses the variables the NVWSC is providing, is available from California Landscape Conservation Partnership website: 

⇒ Decision support for meadow conservation and restoration in the Sierra Nevada Ecoregion