Oregon forests face another tough year as hot, dry summer looms, officials warn
SALEM, Ore. (KATU) — Oregon’s trees are heading into another difficult year as the state braces for a hot, dry summer that forestry officials say is increasingly tied to climate change.
Conditions this spring are already similar to those in 2015, a year marked by peak high temperatures and drought.
The concerns come after a winter that tied 1934 for the warmest since accurate records were kept beginning in 1896, according to the National Oceanic and Atmospheric Administration.
State forestry officials say Oregon’s trees have been experiencing chronic stress from hot droughts for at least a couple of decades. While there have been occasional breaks, frequent or long-duration warm and dry conditions have compounded over time, taking a toll on many trees.
The dead tops of the middle Douglas-fir shows clear signs of damage from drought, which is an increasing risk to Oregon’s trees/Oregon Dept. of Forestry image
Among the contributing factors cited are higher-than-average temperatures, inconsistent precipitation, including more precipitation falling as rain than snow, and earlier snowmelt.
Oregon Department of Forestry Forest Entomologist Christine Buhl said spring weather can be especially damaging because it coincides with trees’ most active growing period.
“A warm or dry spring is particularly harmful for trees as this is their most active growing period. This stress reduces growth, weakens defenses against opportunistic insects and diseases, and can outright kill tissues or whole trees,” Buhl said.
Buhl also warned that warmer conditions can benefit tree pests.
“Warm winters reduce pest deaths from cold, increasing their growth or number of pests. It also extends the range of less cold-tolerant pests, and lengthens their feeding periods,” she said.
Buhl offered several recommendations for landowners to help trees withstand drought stress.
She advised planting species and seedlots only within their current and climate-projected range, avoiding planting seedlings during dry seasons, and keeping roots moist and out of direct sun during planting.
Buhl also recommended reducing competition for moisture by controlling weeds and reducing stand density to match the carrying capacity for the tree species, site quality and climate.
If currently adapted species or seedlots are struggling, Buhl said landowners should consider shifting to a nearby, more drought-tolerant seedlot, or in extreme cases a more drought-tolerant species. She also noted that native understory vegetation and mulch can help retain soil moisture.
Additional guidance included avoiding root compaction from heavy equipment when soil is wet and avoiding fertilizing drought-stressed sites because fertilizer increases biomass and therefore water requirements.
More information about trees and drought can be found on the Oregon Dept. of Forestry website.