AIR POLLUTION AFFECTING NEW GROWTH ON OAK
CALIFORNIA

As a result of the combined effects of ozone, nitrate deposition, acid fog and acid rain, most of the trees are unable to produce new growth. Arborists are pruning fewer and fewer trees because they are not growing.  However, some trees appear to be a healthy, deep green color.  This is decieving, the deep green coloration comes from the nitrate deposition which has a fertilizing effect on the tree.  Once the nitrates become too high in the soil, the microbial community collapses along the with mycorrhizae and tree death occurs.  This oak death is not sudden, it is an accumulation of insults over many years, that is manifesting itself at a rapid pace.  I believe , as many horticulturists do, that we have reached a threshold of rapid tree decline and death nationally if not globally.

Photo & caption provided by:

Ralph Zingaro
Bioscape, Inc.
4381 Bodega Avenue
Petaluma, CA 94952

E-mail: ralph@bioscape.com
Web site: www.bioscape.com

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Contact Gerry Hawkes: ghawkes@eco-systems.org