New and Notable

Mobile App for Permanent Plots (MAPP)

Thanks to two students in Computer Science at Oregon State, PNW-PSP has a new mobile application for data collection.  We call it MAPP – the Mobile App for Permanent Plots.  During the 2019-2020 school year, Joey Landreville and Sergei Poliakov developed the app as part of their year-long senior capstone class, working under the direction of Rob Pabst.  The capstone class is designed to give students real-world experience working as developers for a client on a specific project.  Joey and Sergei developed the app using Open Data Kit (ODK-X), a free and open-source software system.  ODK-X has built-in tools for data collection, however customizing those tools for the permanent plot program required detailed programming in JavaScript, css and html. 

MAPP screen

The interface for MAPP mimics the paper forms that field crews have used in the past, and comes with the bonus of drop-down menus, real-time data validations, and data synchronization with a PostgreSQL database.  Together, these features will facilitate efficient data collection in the field, reduce data recording errors and data processing time, and provide significant cost savings compared to proprietary software.  MAPP is deployed on semi-rugged Android tablets and is performing flawlessly during the 2021 field season.  We are extremely grateful to Sergei and Joey for delivering a great product, to the OSU Department of Electrical Engineering and Computer Science for accepting our proposal as a capstone project, and to the developers of Open Data Kit – a remarkable resource being used worldwide.

Drought, dwarf mistletoe and tree mortality (Bell et al. 2020)

Dwarf mistletoe, a native parasitic plant, commonly infects western hemlock trees in western Oregon and Washington via projectile seeds that land on branches and spread through the tree’s bark. The plant induces tissue swelling and deformities while altering plant physiology, growth, and tree vigor, especially among heavily infected trees. As climate change generates hotter and drier conditions, there is a need to know how parasitic plants, like dwarf mistletoe, interact with climatic conditions to alter tree growth and mortality, and thus forest productivity.

In a new paper published in Global Change Biology, US Forest Service scientist David Bell, along with OSU co-authors Rob Pabst and David Shaw, examined several decades of data gathered from permanent plots at the Wind River Experimental Forest, a 500-year-old forest located in Washington State that is part of the Forest Service’s Experimental Forest and Range Network.  Bell, Pabst, and Shaw studied five repeated measurements of nearly 1,400 individual hemlock trees from 1991 to 2014, examining how western hemlock tree growth and mortality varied with temperature increases, precipitation decreases, and mistletoe infection rates.

Tree growth rates decreased and mortality rates increased during warmer‐drier time periods for all hemlock trees, regardless of infection status. Growth reductions and increases in mortality were also related to mistletoe infection intensity, most notably during the warm and dry measurement intervals.  Forests of western Oregon and Washington are often assumed to have low vulnerability to climate change relative to drier  forests east of the Cascades. However, this long-term research revealed an unrecognized vulnerability of west-side forests to climate change as a function of common, native pests and pathogens.

For managers, these findings suggest that native pest and pathogen management may be a key component of preparing for climate change.

Witches broom

DM-infected branch, close-up

“Big Plot” coming to the HJ Andrews

Joe LaManna

This summer, Dr. Joseph LaManna and his team from Marquette University (http://www.lamannalab.org/) will begin installation of a 25-hectare “big plot” at the HJ Andrews.  The HJA Big Plot will be the first of its kind in Oregon, adding to a growing network that is part of the Smithsonian Institution’s Global Earth Observatory Network, or ForestGEO (https://forestgeo.si.edu/).  Presently there are 67 big plots in 27 countries around the globe, representing millions of trees and thousands of species.  The location of the HJA Big Plot and smaller “satellite plots” will be arrayed across an elevation-climate gradient within the HJA, leveraging and expanding on our existing network of permanent plots.  Dr. LaManna’s research will examine how interactions between forest tree species and their natural enemies or mutualists influence community assembly along the climate gradient.  He will also study density dependence and genetic diversity of tree seedlings in relation to nearby mature trees.  The PNW-PSP team and the HJ Andrews welcome Joe and this partnership with The Smithsonian ForestGEO network!

LiDAR Change Detection: Coupling remote sensing with permanent plot data

Forest landscape change depends on fine-scale patterns of tree growth, mortality, and recruitment.  While long-term forest inventory plots provide some of the most robust assessments of individual- to stand-level changes, their spatial extent (< 4 ha) limits their capacity to represent dynamics across the entire landscape. In this study, we are using high-resolution remote sensing of vegetation structure (i.e., light detection and ranging, or LiDAR) from multiple years coupled with our long-term measurements and stem maps to assess patterns of tree mortality and growth over complete landscapes. This research aims to both (1) understand the landscape drivers of forest growth and mortality, and (2) map areas of forest vulnerable to changing environmental stressors.LiDAR change detection

     Examples of canopy height losses from 2008 to2014 associated with individual tree mortality and canopy gap formation.

Long-term Response of Coastal Forests to Wind Disturbance

Mark Harmon and Rob Pabst have authored a new paper in a special issue of the journal Forests on wind disturbance (http://doi.org/10.3390/f10020119).  Harmon and Pabst took advantage of tree measurements spanning 78 years in ten plots at Cascade Head Experimental Forest to examine the cumulative effects of wind disturbance on forest structure, tree mortality, and net primary productivity.  This set of permanent plots was established in 1935 for the purpose of understanding growth and yield of coastal forests dominated by western hemlock and Sitka spruce.  However, since 1951 the plots have experienced hurricane-force winds at least ten times, providing an opportunity to examine long-term response of coastal forests to wind.  Not all plots were substantially impacted by all the storms; rather, the major wind events had differential effects on the plots, suggesting that wind impacts at a broader landscape level are cumulative over time.  Key findings include: (1) the proportion of wind-related tree mortality has increased 5- to 8-fold since 1940, and (2) despite the increase in wind-related tree mortality over time, impacts to net primary productivity were only noticeably when biomass loss exceeded 50%.  The long-term nature of this and other permanent plot research offer poignant lessons in how repeated observations over long time periods help us understand how and why forests change.

CH08 sunshineCH08 windthrow