A few folks, most recently Norm, have asked if I intended to post at Crumb Trail any longer. I let the domain name lapse, and haven't kept up the old Blogspot version from back in the day.

I don't have the time for blogging I once had. So, I'll just combine them, drop the crumbs here so to speak, and follow paths as time permits.

For example:

It seems obvious, but not well quantified, that Soil nutrition affects carbon sequestration in forests.

Building on preliminary studies reported in Nature, the researchers found that trees can only increase wood growth from elevated CO2 if there is enough leaf area to support that growth. Leaf area, in turn, is limited by soil nutrition; without adequate soil nutrition, trees respond to elevated CO2 by transferring carbon below ground, then recycling it back to the atmospheric through respiration.

And there are implications. Looking at the beast with a slightly different lens we see that Drop in acid rain altering Appalachian stream water

Appalachian hardwood forests may be getting a respite from acid rain but data from a long-term ecological study of stream chemistry suggests that the drop in acid rain may be changing biological activity in the ecosystem and hiking dissolved carbon dioxide in forest streams. . .

DeWalle, whose work is funded by the U.S. Environmental Protection Agency, thinks that by reducing pollutants emitted to the atmosphere, we are creating a different set of conditions for organisms in the soil. The rising dissolved carbon dioxide in the streams, he suggests, might be traced to increased respiration by these organisms.

He explains that organic matter broken down by these organisms generates byproducts such as carbon dioxide, water and residual dissolved organic matter. The increased respiration, he adds, may be gradually increasing soil carbon dioxide and reducing the amount of residual organic matter. As the organisms break down more of the organic matter, there is less of it leaving as dissolved organic matter in stream water.

"There have been some experiments where they added nitrogen to the soil and saw a reduction in soil respiration. We have of course, reduced the nitrogen, and indicators of stream chemistry suggest that this may have caused the opposite reaction and stepped up the respiration," says DeWalle.

It isn't just that trees grow less, even in elevated CO2 environments, when nutrients, especially nitrogen, are not in sufficient supply. Soil organisms are affected in similar ways. In effect, they are all living off their "fat", burning organic matter rather than making more of it.

There are effects further afield as well.

Penn State researchers are already seeing increasing amounts of silica and sodium in streams which may be from the weathering of minerals and sandstone bedrock, caused presumably by the increased carbonic acid in soil and groundwater.

"If you have higher carbon dioxide in the soil, you get more carbonic acid in the groundwater, which increases the weathering of minerals. You would not normally expect weathering rates to increase with reduced acid rain,"

It's, uh, complicated. Complex too. And it isn't just a US thing. In fact, our situation pales in comparison to others.

"What we have seen in our latest climate simulations is that the ?Asian haze? is having an effect on the Australian hydrological cycle and generated increasing rainfall and cloudiness since 1950, especially over northwest and central Australia. The effect occurs because the haze cools the Asian continent and nearby oceans, and thereby alters the delicate balance of temperature and winds between Asia and Australia. It has nothing to do with Asian pollution being transported directly over Australia."

Dr Rotstayn says this implies that decreasing pollution in Asia later this century could reverse this effect and lead to an increase in Australian drying trends.

We seem to be hulking, clumsy naifs in the china shop, everything we do - or don't do - breaks something. "You can't go back and you can't stand still / If the thunder don't get you then the lightning will"

It seems to me that this isn't new. It's just that we are obsessing about it a lot these days, in part because we are so much better at information gathering and dissemination, and in part because we can imagine being in control, being able through "political will" to alter behavior and avoid breaking so much china. I think this is only imaginary, that our frenzied attempts to avoid breakage will not succeed, or even makes things worse, because we really don't know what we are doing as yet.

"Human alterations to the natural fire regime, especially decades of fire suppression, have changed oak-dominated ecosystems in southern Ohio and throughout the eastern US," reported Petersen. "As a result, there is a preponderance of shade tolerant hardwoods that are preventing oaks and other native species from regenerating."

The oak canopies of remaining forest fragments are deceptive, according to the researchers, who found that oaks are not thriving well beyond the seedling stage, with few developing into older life history stages, including juveniles, saplings, and poles.

"Eventually this means the demise of oak trees and other less shade tolerant plant species in future years," said Drewa.

While red maples and other shade tolerant species may experience delayed recovery after summer fires, oaks in particular have been shown to experience less damage because their roots are more expansive and provide greater storage and greater seasonal stability of carbohydrate reserves.

To save the oak forests, Drewa and Petersen are advocating studies that include summer fires as experimental treatments. They caution against fires in other seasons that might foster proliferation of plants other than oaks and other less shade tolerant species.

It's old news, almost common knowledge at this point, that western forests are fire adapted and have been harmed by fire suppression. Now it appears that even eastern hardwood forests are changing in profound ways for the same reasons. Who knew?