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<TD><SPAN class=inside-head><STRONG><FONT size=5>Warming trend visible in
the trees</FONT></STRONG></SPAN></TD></TR></TBODY></TABLE><SPAN
class=datestamp>Updated 1/16/2007 12:08 PM ET</SPAN>
<DIV class=byline>By Patrick O'Driscoll, USA TODAY</DIV>
<DIV class=byline> </DIV>
<DIV class=byline> </DIV>
<DIV class=inside-copy>Rising temperatures are allowing Southern trees to thrive
farther north and stressing trees used to colder weather, according to new
national guidelines issued by planting experts.</DIV>
<P class=inside-copy>The National Arbor Day Foundation last month updated the
Agriculture Department's "hardiness zones" map, which was last issued in 1990.
The group acted after noticing that some tree species were thriving where they
had not before, while others were doing poorly in what had been a suitable
region on previous maps.</P>
<P class=inside-copy>The shift in zones may allow people in northern areas to
experiment with flowering Southern trees such as apple and cherry where they
used to plant only fir, spruce and pine, says group spokesman Woodrow
Nelson.</P>
<P class=inside-copy>The map divides the nation into 11 planting zones tied to
average low temperatures. It shows significant boundary changes as the continent
has warmed. For example, in southern Texas, the edge of one zone moved more than
200 miles north to the Panhandle. A few locations jumped two zones.</P>
<P class=inside-copy>The map is based on 15 years of minimum temperatures from
5,000 observers used by the National Weather Service.</P>
<P class=inside-copy>Last year was the warmest on record for the USA. Twelve of
the top 25 warmest years have been since 1990.</P>
<P class=inside-copy>The foundation cautions not to dig up gardens or cut down
trees just because zones have shifted. The map is a guide for new plantings,
especially for seedlings, which are more vulnerable to temperature change than
mature trees.</P>
<P class=inside-copy>The Agriculture Department has been reworking its map for
several years using 30 years of data instead of 15 but has set no release date.
The department's Kim Kaplan says the 1990s "were a very warm decade, but is that
a weather cycle or is that a climate cycle? We think 30 years represents the
best compromise, smoothing out the natural fluctuations of weather."</P>
<P class=inside-copy>Nelson says the foundation will distribute 10 million
seedlings this year. "Those need to be planted under the most up-to-date
information."</P>
<P class=inside-copy> </P>
<P class=inside-copy>See entire article with interesting comparisons using
maps.</P>
<P class=inside-copy> </P>
<P class=inside-copy> </P>
<P class=inside-copy>W.</P></DIV></BODY></HTML>