Forest Pathology Collaborations

Shore pine mortality and decline in southeast Alaska

This project investigated shore pine (Pinus contorta ssp. contorta) mortality and damage in southeast Alaska, a trend revealed through comparisons of Forest Inventory Analysis (FIA) re-measurement data from 2004 through 2008. This study was initiated to better understand the recent decline in shore pine biomass in southeast Alaska. The objectives were to gather baseline information about the pathogens, insects, and other damage agents of shore pine and to evaluate the extent of mortality and dieback across southeast Alaska. We wanted to determine if there was evidence of a recent pulse in mortality among the largest size class of shore pine; identify the primary causes of shore pine crown dieback; and evaluate potential spatial patterns of dieback or mortality. We identified gall rust severity of infection as a primary driver of crown dieback occurrence, and bole gall presence as a predictor in the percentage of crown dieback. The causes of tree mortality are difficult to evaluate over the short term, but the long-term monitoring plots installed in this study will be tracked over time and used to identify the abiotic and/or biotic factors leading to shore pine decline across the region.

Collaborators: Robin Mulvey (USDA State and Private Forestry) and Tara Barrett (USDA Pacific Northwest Research Station)

Sudden Oak Death monitoring on the Central Coast

Sudden Oak Death (SOD) early detection surveys have been conducted for over a decade (2000 – 2014) in California’s coastal oak and evergreen forest ecosystems. These surveys are designed to track the spread of the Phytopthora ramorum pathogen along California’s coastal forests to support mitigation and management efforts. Past surveys supported targeted efforts for treatment strategies as well as research methodologies. Information gathered informed understanding of infection extent and movement, while also tracking spread from currently infected areas to adjacent, uninfected forest ecosystems. The current southern extent of the pathogen lies within Monterey County. To date, P. ramorum has not been documented in San Luis Obispo County. Monitoring at this range edge is intended to capture any migration of the pathogen further south.

Collaborators: Kim Corella (Cal Fire)

A Silvicultural Approach to Monterey Pine Regeneration and Pitch Canker in the Año Nuevo Native Stand 

Pinus radiata (Monterey pine) is an endangered, endemic California conifer, yet is one of the most widely planted and cultivated pines across the globe. Native populations are limited in extent and were drastically impacted by Fusarium circinatum (pitch canker) introduction (ca. 1986).Assessment of pitch canker effects on grown Monterey pine trees became a subsequent research priority but failed to study the fungus’s effects on regeneration. The objective of this study was to fill this knowledge gap by 1) determining the relationship between pitch canker infection severity and tree phenotype, genotype, and spatial orientation with planted stands, 2) quantifying survival rates as a function of change in tree, stand, and infection rates over time, and 3) assessing the influence of silvicultural treatment and parent tree genetics on infection resistance and survival of planted seedlings. Areas of the Año Nuevo stand were experimentally treated using group selection and either lop-and-scatter or pile burn. Treated areas of the Año Nuevo stand were planted, and the seedlings were tracked over 14 years. A generalized linear mixed model was used to determine the primary drivers of seedling success and resitance to disturbance, and DBH and parent tree genetics appear to be the most important factors. Findings from this study will support forest management in both the native stands and planted stands around the world and can be used to better predict seedling survival and resistance following pitch canker infection.

Collaborators: MS Student Tori Norville & Dr. Doug Piirto (Cal Poly)