Public perception of climate change may differ from yours and mine. Arborists know all too well the reality of climate change. We work outdoors every day, and we see the changing weather patterns and their effect on trees and shrubs in the landscape. It would be wise to take note of these changes. They will influence the advice we give our clients and the plant health care we provide.
Climate change isn’t going away, at least not in our lifetime, and global temperatures will continue to rise. The Intergovernmental Panel on Climate Change forecast is for a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century. It is estimated we will see a significant increase in the frequency of El Niño events, which affect climate and ecosystems alike. We have seen some of the warmest temperatures on record during the past decade. Yellowstone National Park has seen spring arrive one month earlier in the last 30 years. Environmental disasters have been on the increase.
What does this mean? Many people expect to see or experience hotter summers and warmer winters. The experts tell us something quite different. We are told to expect extremes!
For example, some regions will experience more frequent and heavier rainfall events. Others will see hotter and drier summers. Colder winter temperatures have extended deeper to the South and the East Coast.
Have you contemplated those changes and what vulnerabilities they might have on the plants we collectively manage?
Warmer winter temperatures could mean:
- Disruption to plant-hardiness development and dormancy phases.
- Earlier springs, resulting in early bud development, making those developing buds susceptible to late-spring freeze damage (flower loss and lack of fruit set).
- More frequent ice storms and tree damage.
- An increase in damaging insect populations, due to a lack of extreme cold temperatures, which moderate population cycles.
- Winter chill requirements not being met for many species, especially detrimental for fruit-tree production.
- Rapid cooling, following an unseasonably warm day, resulting in tissue death.
- Changes in phenology that can adversely affect pollination success and maple sap flow.
Occasional colder winter-temperature extremes could mean:
- Decreased survival rate of some damaging insect-pest populations, as well as beneficial insects.
- Winter kill or dieback of plants used inappropriately, i.e., in the wrong hardiness zones.
More frequent and heavier rainfall events could mean:
- Disrupted growth due to increased flooding and saturated soils.
- Increased incidence of disease pathogens.
- Nutrient deficiencies.
- Stronger storms and damaging wind events.
- Storms of quicker succession.
- Damaging change in water cycles.
Warmer, drier summers could mean:
- Severe drought and reoccurring drought conditions.
- Nutrient deficiencies.
- Opportunistic-insect-pest infestations and diseases due to plant stress.
- Environmental/ecological stress.
- Forest fires.
- Overall changes affecting the rhizosphere and soil ecology.
- Promotion of invasive species.
- An additional generation of insect pests per year.
Ultimately, all the above will influence species range, regeneration rates and carbon loss from the soil.
When diagnosing and explaining tree issues to our clients, things may not be so clear. If we are only seeing an expression of symptoms, in the absence of signs, we must look back at local weather conditions to piece together a plausible scenario to explain a tree’s demise.
I have been downloading NOAA (National Oceanic and Atmospheric Administration) online weather data for my area for more than a decade now. I find these preliminary, monthly climate-data reports to be quite helpful in my diagnostic process.
Thus, the changing world we live in. How will you be prepared?
Steven F. Pregler is an ISA Certified Arborist and retired city forester for the City of Dubuque, Iowa.
