Don: Site index (SI): a measure of forest site quality (i.e., the actual or potential productivity of a site) based on the height of dominant trees at a specified age. Twenty-five years is oftern used for Southern pines.
A numerical indication of the quality of a given site for production of a given species of tree. The number assigned to the site represents the average height in feet of dominant trees of that species after fifty years of growth. Good question. Tim On Mon, Jan 4, 2010 at 12:58 PM, DON BERTOLETTE <[email protected]>wrote: > Bob/Gaines- > Guess things are different in the East...I thought that site index was the > result of height grown per hundred years... > -Don > > ------------------------------ > Date: Sun, 3 Jan 2010 23:16:10 +0000 > > From: [email protected] > To: [email protected] > Subject: Re: [ENTS] White pine growth rates--something of interest about > growth possibilities > > > Gaines, > > Very interesting. Thanks for digging the research up. I anxiously await > hearing what others like Lee have to say. > > ENTS white pine measurers are divided into two camps, the liberals and > conservatives. The liberals allow for the possibility of pines in the 250 > feet and over class. Conservatives consider 200 feet to be the maximum for > the species with an occasional pine getting taller to perhaps 220 feet in > historical times. I am a member of the latter group. > > Bob > > > ----- Original Message ----- > From: "spruce" <[email protected]> > To: "ENTSTrees" <[email protected]> > Sent: Sunday, January 3, 2010 5:18:59 PM GMT -05:00 US/Canada Eastern > Subject: [ENTS] White pine growth rates--something of interest about growth > possibilities > > There is some research about the growth rates of white pines that may > be of interest to white pine enthusiasts. For a bit of background to > make the context of the research I am quoting clear: in forestry, > growing sites for various eastern trees are classed by how tall a tree > can grow in 50 years. This is called the "site index" for each > species relative to each site. > > For white pine, the site indices range from 60 feet--for a rather > poor site--to as much as 120 feet for the best sties. It may be > possible that there are some sites with an index of over 120 feet, but > if so, I assume they are very, very rare. In fact, most commonly, the > best white pine sites are between 90 and 100 feet, which I commonly > see quoted for most class II soils. I believe 120 feet is fairly > unusual--I know of one just site, a very rich stream bottomland site > that is probably a class I soil, that may have that kind of potential. > > OK, enough for the basic background. Here is the interesting thing > I just learned: If a white pine grows 120 feet in 50 years, this same > tree on this same superior growing site, after age 55, will not grow > any faster than a tree growing on a relatively poor site--index 60. At > age 55, both trees--the one growing on the relatively poor site, and > the one growing on the very rich site, will be growing at the same > rate--roughly one foot per year. > > So, all the difference between the height of a white pine tree > growing on an excellent growing site, and the one growing on a poor > site, occurs during the first 55 years. Of course this does not > include any factors that may distinguish sites based on factors such > as ice and wind breakage. > > I think this reflects on the question of how tall white pine trees > can grow, in that those growing on the very best sites may not grow > significantly taller than those growing on the lesser, but still very > good sites. Thus, if a growing site is rated at 120 feet, over the > life of a white pine tree, the final height of the tree will be just > 20 feet taller than a tree growing on a site of index 100. > > To explain a bit more, if we want to speculate on the possibility > of white pines growing to 200, or the oft quoted height of 250 feet, > the idea that the 200 plus trees grew on the very best sites, and > those sites are now no longer available for growing pines because they > are now farmalnd, or whatever, should be less of a factor in our > speculations. The difference in the ultimate height of the trees will > be only 20 feet or so. So even if we want to argue that the best > sites could grow pines taller than what we now see--about 175 feet > max--then the potential was for 195 or so, certainly not much above > 200, and certainly not 250 or anything like it. > > This research is summarized (with citatiion) in the USDA Forest > Sefvice manual titled "Silvics of North America." The URL is: > http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm > > This is written from a forestry perspective, but contains a lot of > information about tree growth, etc of interest to any tree lover. > > --Gaines Mcmartin > > -- > 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]<entstrees%[email protected]> > > -- > 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]<entstrees%[email protected]> > > ------------------------------ > Hotmail: Powerful Free email with security by Microsoft. Get it > now.<http://clk.atdmt.com/GBL/go/171222986/direct/01/> > > -- > 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]<entstrees%[email protected]> > -- 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]
