LEAF LOSS REPORT - SEPTEMBER 21, 1998
by Gerry Hawkes
Woodstock, Vermont U.S.A.
Leaf drop is slowly, but steadily picking up speed with leaf accumulations on the ground in some locations equal to that of mid to late October. Certain areas seem to be harder hit than others. Premature leaf drop in the Woodstock area seems to be somewhat worse than the average of what I have seen in limited travels around Vermont, but certainly there is plenty of premature leaf drop in other places.
Following are some quick leaf drop observations by species:
Ash (white) - looks quite healthy this year, but is affected by episodic leaf curling
Alder (speckled) - leaves continue to thin as they have over the past 3 years - many now have less than half the leaves they should
Apple (common) - Individual leaves continue to yellow and drop while twigs and branches continue to die back. A rough guess is that an average wild apple tree has only 2/3 the leaves it should have.
American Beech - Yellowing of leaves and dieback seem to have accelerated this year.
Black Ash - Not widely observed, but has been suffering severe dieback and mortality for the past few years.
Balsam Fir - Yellowing of a few branchlets has been seen, but in general nothing too severe has been noted.
Black Locust - Severe browning and leaf drop has been observed in almost all locations again this year. It is assumed that leaf miner is at least partially responsible.
Balsam Poplar - Virtually all trees observed lost virtually all leaves in mid-August as they did in 1996 (but not in 1997).
Basswood (American) - Yellowing and dropping of significant numbers individual leaves is increasingly severe this year. Dieback and mortality continue to worsen.
Butternut - Dying fast.
Black Cherry - Yellowing and dropping of significant numbers individual leaves is increasingly severe this year. Crowns continue to thin.
Eastern Hemlock - For the third year in a row yellowing of entire branchlets can be observed on almost any hemlock tree. Estimated percentage of canopy affected ranges from 1% - 15%. Branchlets do not recover. No woolly adelgid or hemlock loopers observed.
Norway Spruce - For the past 15 years needles have been steadily thinning with dieback and mortality increasing. For the past two years significant loss of new growing tips has been observed, especially in the winter (squirrels & wind were not the cause).
Oak (Northern Red) - Premature leaf drop, crown thinning and premature dieback of lower limbs continues. In some cases this has resulted in tree mortality. Healthy red oaks should hold onto rust colored leaves through a good portion of the winter.
Poplar (quaking aspen & bigtooth aspen) - Many poplars have lost the majority of their leaves although some are still fully foliated. Poplars should hold on to their golden leaves well after most other trees drop theirs.
Red Maple - Close observations of red maple have not been made, but it has been noted that they are affected by episodic leaf curling.
Red Pine - Many are exhibiting browning and excessive needle loss.
Red Spruce - The steady needle loss and mortality of the past 30 years seems to be accelerating in the trees that remain. Some trees have entire limbs that are yellowing and dying now.
Shad or Serviceberry - Leaves began yellowing and dropping in mid-August as they have for the past three years. Doubt that they can survive much more of this.
Sugar Maple - Crowns have been abnormally thin since the mid-1970's. Episodic leaf curling and abnormal leaf drop first noted in July 1996. Episodic leaf curling has worsened significantly since then and leaf drop has picked up speed. In some areas widespread browning of leaves and foliar caterpillar infestations have developed over the past 2-3 months. Dieback is evident in many trees along with significantly elevated levels of mortality. Higher elevation sugar maples were seriously damaged by the January ice storm - brittle wood is suspected as a contributing factor.
Sumac (Staghorn) - Foliage is thinner than normal in many areas
Willow - Many willows have exhibited a steady loss of foliage over the past three years.
White Birch - The majority have lost nearly all their leaves after they turned brown in August. Higher elevation white birch suffered severe ice storm damage in January.
White Pine - In some areas significant numbers of white pines have been browning over the summer due to necrosis of the needle tips. This is not the normal annual shedding of needles. Two winters ago white pines along highways in the northeast were seriously browned, but this summer and fall browning can be seen well away from highways. Also many pines are chlorotic (yellowed) and appear to be declining in vigor.
Yellow Birch - Yellowing and premature drop of individual leaves continues to worsen. Dieback is widespread with elevated levels of mortality.
NOTE: This is just a quick overview relating primarily to leaf drop and does not to begin to document all of the symptoms nor the observed 30 year chronology that indicate the forest ecosystem is approaching the point of collapse.
It should also be noted that many shrubs and herbaceous vegetation are also exhibiting browning and leaf drop that parallels that of the trees.
For background reading, "The Dying Of The Trees" and "An Appalachian Tragedy - Air Pollution & Tree Death" as well as an on-line visit to www.AppVoices.org are suggested.
Gerry Hawkes - Bridgewater Tree Warden
Eco Systems, Inc. & Bike Track, Inc.
. . . back to AIR POLLUTION AND FOREST HEALTH NOTES FROM AROUND THE WORLD
. . . to Eco Systems' Home Page
Contact Gerry Hawkes: email@example.com