Dear ENTS, I know of at least two publications that have some evidence of increased site productivity, measured by height growth during the 20th century. presumably, both of these studies used 'on-the-ground' measurements to determine this.
these pubs are: Nigh, G.D., C.C. Ying and H. Qian. 2004. Climate and productivity of major conifer species in the interior of British Columbia, Canada. Forest Science 50: 659-671. and Title: A Generational Change in Site Index for Naturally Established Longleaf Pine on a South Alabama Coastal Plain Site - http://www.treesearch.fs.fed.us/pubs/2443 Author: Boyer, William D. Date: 2001 Source: South. J. Appl. For. 25(2):88-92. Description: Research on longleaf pine (Pinus palustris Mill.) has been carried out for over 50 yr on a coastal plain site in south Alabama. Studies havie included the original second-growth stands and also naturally established third-growth stands. Site index data revealed that estimated site index values for third growth generally exceeded those for second growth. Age 50 site index in 16 study compartments with second growth near index age averaged 66 ft. Estimated site indexfor third-growth stands recorded in 17 different compartments averaged 81 ft. Nine of the 16 compartments with second- growth stands now include third growth about 40 yr in age. This provided an opportunity to make a direct comparison of generational site index differences within the same compartments. Site index for second growth averaged 65 ft (range 61 to 70 ft), while third growth avelraged 83 ft (range 77 to 87 ft). Reasons for this large increase in apparent site quality are unknown, bit since soils are the same, some climate changes may be suspect. neil On Jan 13, 7:35 am, Larry <[email protected]> wrote: > ENTS, After reading this most lenghtly post . Its hard to follow > when we jump from topic to topic and my memory isn't what it once was. > We talked about this in the past. Did anyone mention the higher C02 > levels in the last 100 or so years plays a large factor in these > speedy growth rates along with other factors that have already been > mentioned. I'm finding live oak growth rates to 1/2" radial to 3/4" > thats tremendous. These are live oak stumps 45-50 years old. The mid > growth seems to be the fastest. In older trees the rates are much > slower avg. .125-.25. These rates in live oak have made me re-think > that thousands of years ago the trees would have been even taller. > Larry
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