Lee, Yes more CO2 increases plant growth while I agree that more CO2 in laboratory conditions traps more heat. You admit that scientists have different opinions on the methods for filtering out different factors so it will remain a complicated puzzle. Maybe the best thing to do is to agree to disagree and work on some commonly accepted goals like supporting a real energy policy that will declare a moratorium on all new coal fired power plants and reduce our use of all fossil fuels. I am very concerned with how continued acidic precipitation is changing soil chemistry i.e., leaching important nutrients like calcium and magnesium. While more CO2 increases plant growth, this leaching slows it. We also need to do a better job of protecting more forest land and slowing down deforestation not only here but around the world. I heard the state of Maryland is promoting a no net loss of forest land? Finally, the introduction of non-native plants, insects, and diseases continues to be a major problem which has reduced forest diversity and threatens whole ecosystems.
Too much energy (no pun intended) has been wasted on the CO2 boogeyman taking attention and money away from these other problems. Climate Expert Hansen says we need to keep CO2 levels down to 330 ppm. Well you can just forget about that especially since Obama and Reid have killed nuclear power as an option when they pulled the plug on Yucca Mountain. So if we reduce our forest fuel use while protecting as much forest as we can then I think we won't have to worry about the extra CO2. Some may say that's wishful thinking but I think the cure (cap & trade) being proposed by the climate change scaremongers is much worse than the disease. Mike -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Lee Frelich Sent: Thursday, June 04, 2009 12:58 PM To: [email protected] Subject: [ENTS] Re: High elevation forest response to climate change and other factors Mike: The direct impacts of increasing CO2 would lead to wider rings, due to CO2 fertilization and possibly modestly increased drought resistance. However, severe droughts, competition from other trees and other local factors that affect growth could easily override the rather modest direct impacts of CO2 (i.e. direct CO2 effects may only partially offset other negative influences). Increasing CO2 in the atmosphere causes heat to be retained near the surface of the earth (i.e. global warming), which causes a change in atmospheric circulation systems and redistribution of heat around the world, with varying climate change in different regions (warmer, cooler, drier, wetter in various combinations). If a given region gets drier as a result of climate change, then increased drought frequency will show up as narrower ring indices. It is possible to factor out various influences in tree ring analyses, including factors such as tree age, competition, temperature and phenomena such as El Nino (although climate change itself might change El Nino frequency or intensity, and it might be the object of study rather than something to factor out). These factors can be taken into account in experimental design (i.e. choosing trees that are more likely to be influenced by the factor of interest and less likely to be influenced by unwanted factors in a given study), as well as by filtering the tree sequences themselves. There are hundreds of papers in the scientific literature that present methods for filtering out various factors, and one scientists junk to be filtered out may be another scientists signal to be retained. For example, in many studies of climate, competition among trees is factored out (i.e. information on competition is thrown away as junk), whereas most of my studies have done the opposite, and filtered out the climate influences to retain just the competition signal, because I am interested in releases from suppression in trees and reconstructing the history of succession into gaps. Lee --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
