The Township Treebune

Pennsylvania has always been a state of excellent water. Average annual precipitation across the state is about 40 inches per year, usually well dispersed throughout. And Centre County falls right in that average. Droughts have occurred, but overall there tend to be adequate water resources to support our abundant tree and plant life.

Paying attention to climate change models, and changing weather patterns, the expectation is that Pennsylvania will see an overall increase in precipitation, but the frequency and regularity of rainfall events will decrease – models say that we will see warmer days and more intense storms with periods of dry spells and periodic droughts occurring interspersed throughout the year.

What does a changing climate mean for street trees in Ferguson Township? It might mean more periods of drought that could stress trees and cause forest health issues or tree death.

Just like you and your home, trees have preferences for where they will thrive. Some like more wet soil; some can tolerate drier, sandy areas. While most trees have a wide range of conditions they can live in, planting the right tree for the right site means that a tree’s ability to thrive will occur in those areas that meet its desired conditions. Pay attention to soil characteristics (dryness/wetness, acidity, depth), heat tolerance, and water requirements, and plant trees that will do well in the site you have planned for them.

In times of drought, water for your trees, not your lawn. Trees compete with grass for water. Short, intense rainfall is often only enough to water the grass and its shallow roots. Deep soaking to get at the tree roots means the trees will have adequate moisture to beat the heat of summer. Supplement your yard and street trees as we go through dry spells.

Young street and yard trees with trunks smaller than 3 inches in diameter, need 15 to 25 gallons a week through deep soaking. Trees that have larger trunks are assumed to have a larger root system to draw upon in times of water stress. However, in severe drought, they too will suffer.

Trees can often stand one season of defoliation from stress events such as prolonged drought or tree health issues. Already stressed trees, for example partially defoliated from spongy (gypsy) moth infestation, may be more likely to succumb in times of water stress.

If you see stressed street trees, reach out to the township arborist (arborist@twp.ferguson.pa.gov)