by Annmarie Sheets, Forestry Division
Springtime holds the promises of new beginnings, warmer days and glorious displays of flowers and foliage. It also plays the music of baby birds joining in choruses of chirps and humming bees looking for the sweet nectar of springtime flowers. But did you know that spring is arriving sooner and sooner each year? Scientists are tracking via satellite when the land turns green and are finding that spring “green-up” is arriving eight hours earlier every year on average since 1982, north of the Mason-Dixon Line. Conversely in much of Florida and southern Texas and Louisiana, the satellites show spring coming a little later. It appears that plant and animal biology are responding to global changes in our environment. Humans base biological spring on the tilt of the Earth as it circles the sun; but how do plants and animals know when it’s time to turn green? Some plants and animals use the amount of sunlight to figure out when it’s spring, others base it on heat building in their tissues, much like a pop-up thermometer used in roasting turkeys. It’s all in the timing, biological timing called phenology. This science of determining the timing of nature has been used since the 14th century for the harvest of wine grapes in France. And while there are changes associated with the timing of fall, the biggest leap has been in the timing of spring.
What do these changes mean to our birds, bees, trees and us? These changes require us to be mindful of how we conduct day-to-day business, as well as observing the impact on our habitats. Certain plants and animals are dependent on each other for food and shelter. If plants bloom or bear fruit before animals return or awake from hibernation, these species could starve. Bees are foraging nectar from different plants causing taste and color to be noticeably different and peak honey production is now weeks earlier. Also, trees that bud too early can still be devastated by a late freeze.
As part of our Forestry program, City of Glendale does not schedule large pruning projects for trees at this time. We also take special precautions to watch for signs of bird activity on the ground and scout for trees occupied by nests before beginning pruning projects. On occasion, when the birds are present and the tree does not appear to be at risk, the pruning will be delayed for a few months.
With spring rapidly approaching, you might be thinking about giving your garden a tune-up, especially your trees. Here are some suggestions for you to consider as you plan your spring tree care for 2009!
- Remove all stakes and guy wires from trees that were planted last year or earlier. Any material that was wrapped around the tree should be removed before the tree’s growth period starts to prevent girdling the tree and causing damage to the trunk.
- Remove mulch from around the trunk of your tree and inspect for moisture or small animal damage. Rodents will feed on the thin bark at the base of trees during the winter months.
- Prune any damaged branches. A torn branch will not heal quickly, leaving an open wound that can attract all kinds of invaders. A properly executed clean cut will close properly and the tree will respond with hormones to wall-off disease and insects. Obtain the proper permit for indigenous trees and for any pruning cuts 1” in diameter or larger. You may obtain a permit from our website, www.glendaletrees.org.
- Inspect the tree for any over-wintering egg masses. This will be easier to do without leaves on the tree.
- Make your mulch ring wider to help conserve moisture. Eliminating turf from around your tree eliminates competition for moisture and nutrients.
- Do a soil test to see what nutrients are in short supply for your tree. Garden supply centers have simple testing kits that will help you fertilize your tree and amend your soil with the correct nutrients it may need.
(Tree care information courtesy of Jay Banks, ISA Certified Arborist, 2008)