PS 32-198 - Parameterizing five Pacific Northwest (USA) tree species in a process-based forest landscape simulation model

Tuesday, August 8, 2023

5:00 PM – 6:30 PM PDT

Location: ESA Exhibit Hall

Presenting Author(s)

SK

Sofia Saenz Kruszka

Incoming MS student
School of Environmental and Forest Sciences, University of Washington, Seattle, WA
Seattle, Washington, United States

Coauthor(s)

JM

Jenna E. Morris

PhD student
School of Environmental and Forest Sciences, University of Washington, Seattle, WA
Seattle, Washington, United States
KB

Kristin H. Braziunas, Ph.D.

Postoctoral Researcher
TUM School of Life Sciences, Technical University of Munich, Freising, Germany, Germany
BH

Brian J. Harvey

Assistant Professor
University of Washington
Seattle, Washington, United States

Abstract: Climate change is increasing natural disturbance activity—including wildfires, insect outbreaks, and drought—creating uncertainty about whether forests will recover to pre-disturbance conditions or develop along altered successional pathways. In the Pacific Northwest (PNW, USA), warming is projected to shorten fire-return intervals and alter post-fire tree establishment, raising concerns about future forest trajectories. Given the long time-scale of forest development in the PNW, landscape simulation models can address knowledge gaps about likely future forest pathways and support understanding of the future range of variation in forest structure and composition. Unlike commonly used growth and yield models, process-based, spatially explicit landscape simulation models can dynamically forecast changes to vegetation under novel climate and disturbance conditions, enabling managers and decision-makers to implement ecologically and socially informed climate adaptation strategies. The individual-based forest landscape simulation model iLand was previously parameterized for tree species present in H.J. Andrews Experimental Forest (HJA) in western Oregon, USA, but five species endemic to the broader PNW are not currently included: Callitropsis nootkatensis, Taxus brevifolia, Populus balsamifera ssp. trichocarpa, Cornus nuttallii, and Prunus emarginata. Here, we present the methods and tools for parameterizing these five additional species in iLand in order to extend model use to the PNW region west of the Cascade Mountains. Drawing from a network of permanent field plots distributed across Washington and northwestern Oregon, USA, Forest Inventory and Analysis (FIA) program data, and national climate and soil databases, we constructed an initial dataset for simulating our focal tree species in the western Cascade Mountains. To assess the suitability of our permanent plot network, we used soil and climate data to compare environmental conditions of our field plots across the PNW with two regions previously developed in iLand: HJA and the Northern Rockies. We then identified field plots across the PNW representing a gradient of stand development stages and site productivity. Initial comparison of climate conditions show that the temperature–precipitation climate envelopes of HJA and the Northern Rockies heavily overlap with that of our surveyed plots in western Washington and Oregon, and in eastern Washington, respectively. This preliminary assessment suggests that our permanent plot network represents a wide range of climate conditions across the PNW, and will effectively support the parameterization, calibration, and evaluation of the five additional species on the west side of the Cascades. Future extension of iLand to the broader PNW will facilitate exploration of management-relevant questions across landscapes in the region.