Dear Bill,

I have a few comments on the article dealing with nutrient depletion in forests that you published in the July, 1998 issue of the Voice.

The data presented on nutrient depletion resulting from timber harvesting are important and no doubt valid for the study areas. Nutrient depletion is an enormous problem that needs to be recognized and addressed. However I believe that most studies done so far have a fundamenta failing. They do not consider the nature of substrate underlying these forests in enough detail. The nature of this substrate depends critically on the underlying rock type and, in the cases of glacial till, colluvium and alluvium, the source material. Thus it is meaningless to speak of the nutrient characteristics of forests types such as Northern Hardwood, Spruce-Fir or Central Hardwoods. These forest types are largely the result of climate but details of their makeup - herb and even tree composition and abundance, nutrient availability etc. - are functions largely of the substrate. Thus much of the work done to date, including that of Likens et al. (1977) cannot be extrapolated.

These conclusions result from our studies in Virginians for Wilderness "Forests of the Central Appalachians Project" for which we have done inventories of many forest types. These studies also show that nutrient availability and floral composition of different Old Growth forest types is a function of the underlying rock type, nutrient transport and topography as well as climate.

A full explanation is presented on our website in the article "Exploring Nature's Multidimensional Space: the Forest Example" at http://www.spies.com/~gus/forests/space.htm

Bob Mueller, July 23, 1998

Virginians for Wilderness

In [your] fine letter [you] have hastened to point out that nutrient quantity has more to do with geological substrates that anything else. This is true, of course.

To characterize these few study sites as Northern Hardwoods, Loblolly Pine, Oak, etc. is not an adequate description. The most infertile site by far is an Oak stand on sandy soil in Connecticut; so we have a little more information there. Also further along, in Federer, et al., aspects of glacial till effects on nutrient availability is described.

Let’s let the story unfold, and let these careful forest scientists tell us what they are willing to say. These studies are now ten years old, and we have no new ones of this nature. We must make the most of them.

[You] suggest that the work done cannot be extrapolated. What [you] mean is that probably no reputable scientist working in this field would care to extrapolate these few widely ranging results. I, however, do; because it is of "enormous" importance – as [you] say.

I (someone) must; because there is an extensive Pottsville Sandstone, for which there are no such thorough studies, that is very infertile, extending through West Virginia into Pennsylvania. It is, in fact, the most studied by forest hydrologists from Penn State University. They would like to extrapolate, but are aware of the difficulties and concerned about their reputations. I have no great standing to lose, but I would like to assure you I am to a considerable extent aware of the difficulties. Mine is not a casual extrapolation then, and as [you] might expect, it has a lot to do with geological richness. D. G. July 25, 1998.