In a message dated 97-05-28 10:38:23 EDT, you write: << Since the volume of hardwoods in Alabama has increased by 85 percent since 1952, I assume the emission of hydrocarbons by hardwoods has also increased by 85%. If a few sweetgum and sycamore trees cause air quality problems in cities in California, how much air pollution would 57 million cubic meters cause in Alabama? >> I wouldn't make the same assumption and I would expect only a weak correlation between wood volume and emissions. I'll state up front that this is speculation on my part as I have not seen anything written on this subject. However, if emissions occur primarily through the stomata of the leaves of the hardwood trees (and not from the wood), then the correlation between emissions and wood volume may be very weak. I would expect that a very young stand with neglible wood volume but whose canopy fully occupies the site may emit just as much hydrocarbons as a mature stand with very high wood volume. Indeed, it might emit more on a unit area basis because young stands are generally physiologically much more active than mature stands. Certainly there are FOREST subscribers that are familiar with actual studies and data that may support or refute my speculations. A much more important question is whether we should be referring to hydrocarbons emitted by trees as pollutants. All natural streams and water bodies have mineral salts and organic acids and you name it dissolved and suspended in them, even without man's ifluence. Are they all polluted? Is distilled water the only water that is not "polluted"? Is their any evidence that any indigenous plants and animals that are exposed to hydrocarbons emitted by native hardwoods suffer any deleterious effects from this exposure?...i.e., that they are not adapted to this aspect of their natural environment? And even if they do, is it correct to speak of a naturally occurring phenomenon as pollution? Roy Hagen Cloquet, MN, USA
Mail converted by
MHonArc 1.1.0