Characterizing trends in forest site productivity using high-resolution climate products Western Mensurationists Meeting 2016 Jarred Saralecos – University of Montana, Graduate Research Assistant Advised by – David Affleck and Zack Holden

Summary Motivations Methods Analysis Questions Projected Results Motivations Methods Projected Results Next Steps Summary Motivations Demand for site productivity estimates, landscape scale approaches Methods Data distribution, downscaled climate product, modeling approach Analysis Questions Modeling aims and challenges Projected Results Evaluating site index projections from multiple perspectives Next Steps Exploring management impacts of fine-scale productivity

Vegetation Management in Complex Terrain Motivations Methods Projected Results Next Steps Vegetation Management in Complex Terrain Fine-scale gradients drive large variation in vegetation dynamics There is a challenge in determining the proper tools and data to make informed decisions about: What to plant where How fast it will grow

Motivations Methods Projected Results Next Steps WDNR is seeking a means of estimating forest productivity across their ownership Easily obtained and cost effective Defined by usable metric Works over time and large landscapes X X X

Measures of Productivity Motivations Methods Projected Results Next Steps Measures of Productivity Empirical: Site Index Based on Ht:Age relationships Time consuming, not always available Species specific Resolution based on sample density Process-based: Net Primary Productivity (NPP) gC/m2/yr Conversion of atmospheric carbon into organic compounds Mostly used at continental or global scales Output not in an actionable form for land managers

Motivations Methods Projected Results Next Steps Study Area

Site Tree Data WDNR Forest Resource Inventory System (FRIS) 1991-2013 Motivations Methods Projected Results Next Steps Site Tree Data WDNR Forest Resource Inventory System (FRIS) 1991-2013 Northern Idaho and Western Montana FIA

Scaling Climate in Mountainous Terrain Motivations Methods Projected Results Next Steps Scaling Climate in Mountainous Terrain Mountains create steep biophysical gradients Daily, gridded 250m climate data, 1979-present Radiation Minimum temperature Maximum temperature Atmospheric humidity Precipitation (Prism) Holden and Jolly, 2011

Modeling Site Productivity Motivations Methods Projected Results Next Steps Modeling Site Productivity Topographic Aspect, Elevation, and Slope Climatic Moisture Availability, Radiation, Temperature Integrated climate (Physiological Processes Predicting Growth – 3PG) Landsberg and Waring, 1998 NPP Remote sensing Vegetation indices - NDVI (Landsat)

Modeling Site Productivity Motivations Methods Projected Results Next Steps Modeling Site Productivity Develop relationships between site characteristics and site index Evaluate assumptions and limitations for each approach Apply best fit equations across study area Validation with a subset of the data Explore the sensitivity of site index to change in climate predictors 50 60 70 80 90 100 110 120 130 140 150 160 Mean Annual NPP (gC-1m-1) Site Index50

Analysis Questions Motivations Methods Projected Results Next Steps How do contrasting modeling approaches vary in predicting site index? What climate factors drive site index predictions and do they vary across species and region? How sensitive are productivity predictions to perturbations in climate?

Projected Outcomes Motivations Methods Projected Results Next Steps Topographic approach limited over large areas Climatic approach driven by a sites growth limiting characteristic NPP will provide a more consistent predictor across landscape Vegetation indices (NDVI) limited by status of individual forest stands during period of interest

Next Steps Assimilate climate products for 3PG Motivations Methods Projected Results Next Steps Next Steps Assimilate climate products for 3PG Complete model selection & calibration Explore management impacts: planting, stand biomass accumulation, site quality effect on SDI

Potential Management Impacts Motivations Methods Projected Results Next Steps Potential Management Impacts Regardless of current state, determine most effective species for a given site Dynamic stand growth accounting for varying productivity in-stand Changes in site productivity under changing climatic conditions

Motivations Methods Projected Results Next Steps Questions?