Monitoring Eastern White Pine Decline and its Causes

Eastern white pine (EWP) is a major component of forest types in New England and New York, found on 4.1 million acres and representing key habitat for wildlife. EWP’s regional economic importance is estimated at approximately $30 billion. Thus, sustainability of the EWP resource is a significant regional concern. Over the past decade, regionally prevailing cool and moist weather patterns during key infection periods for needle diseases causing white pine needle damage ( WPND ) and other fungal pathogens such as  Caliciopsis  canker have led to a noticeable regional increase in EWP decline. Over the past two years increased reports of EWP decline, dieback and mortality have been received from natural resource professionals and the public. It is suspected that many cases of EWP decline are tied to chronic stress from repeated defoliation by WPND. WPND is documented as being responsible for 60,218 acres of damage to EWP forests in Maine in 2010 and 12,102 and 3,696 acres of damage to EWP in New Hampshire and Vermont, respectively, in 2012. In 2016, the documented acreage of WPND was 24,000 acres in NH and 30,600 in Vermont in limited aerial surveys. The aim of this multi-state effort is to: (i) identify and sample EWP stands with differing levels of symptom severity; (ii) determine the stand factors associated with WPND incidence and severity; (iii) assess the impact that this long-term disease pressure has had on EWP decline and regeneration and develop management practices to improve EWP health.

Sites were chosen based on a known history of WPND disease (unhealthy) or absence of disease (healthy) from aerial surveys. Stands had over 50% eastern white pine (EWP) basal area and were large enough to accommodate at least three total inventory plots (>5 acres). Plot lay out was based on FIA plot protocol with 4 plots (1 central plot and 3 plots with plot center at 180ft (instead of 120ft) and 120° from each other). A 20 BAF prism was used to determine sample trees. Crown variables and stand variables were measured to reveal trends of EWP health including crown density, transparency, and live crown ratio. The quantity and health of EWP regeneration was assessed. The Survey123 App was used to collect data in the field. Disease samples were sent to diagnostic clinics within the National Plant Diagnostic Network and USFS. 

• 122 stands (4 subplots each) were measured , and 4,419 trees
• Most stands had symptoms of WPND (118 stands) or Caliciopsis canker (87 stands)
• WPND severity is positively correlated with total basal area and white pine basal area and negatively correlated to crown density (also slightly correlated to latitude, longitude, and elevation)
• With the exception of a negative relationship with DBH and incidence of Caliciopsis canker symptoms in seedlings, it is not related to any measured stand variable
• Most samples submitted to diagnostic clinics were positive for the brown spot needle blight pathogen (Lecanosticta acicola), The second most frequently recovered pathogen was Septorioides strobus. Lophophacidium dooksii and Bifusella linearis were also recovered from symptomatic needles
• Regeneration density as negatively correlated with basal area

• Stand basal area is negatively correlated with WPND severity and number of seedlings suggesting that managing stand density would increase resilience to foliar diseases
• Presence of causal agents of WPND was correlated with a decrease in crown density
• Aerial survey, interstate coordination and data collection with Survey123 was an efficient way to collect data from a wide geographic range and yielded interesting results