Barry, Do you think the smaller stunted trees are similar in age to the larger ones nearby? Sometimes stunting is because of high acidity or some exotic mineral formed from the weathering of the bedrock. There should not be that drastic of a difference geologically in this location to cause the stunting. In this location, I do not think they are stunted because of lack of water. From the setting it looks as if they would not need to develop very long roots to reach water - so that is not a likely explanation.
The best suggestion I can make is that this particular area had been subject to a severe fire, maybe from a big brush pile after logging or just brush itself that grew after logging. If the fire is severe enough it will destroy the organic components of the soil and the soil structure leaving behind a mineral soil that will not support many plant species. These are first occupied by some pioneering species, but it will take decades to a couple hundred years before the soil rebuilds enough to support "normal" vegetation. This is what happened at Marion Brooks Natural Area in central Pennsylvania. After eighty or ninety years there are still large section that only are growing blueberries and bracken fern. What trees that are present in the worst hit areas are paper birch and to a lesser extent pitch pine. In your area of the pine barrens the succession is likely first some of the lichens and hedges, then perhaps the pitch pines. But just because they will sprout there does not mean they will grow well. The trees in these areas are typically stunted by the poor nutrients and nature of the soil. I think that is what is happening here. These trees are stunted because they are growing in an area particularly hard hit by fires that ruined the soil structure. Ed http://nature-web-network.blogspot.com/ http://primalforests.ning.com/ http://www.facebook.com/profile.php?ref=profile&id=709156957
