Don: Yes, those at the extremes would be first affected, but only if you are comparing stands on soils with the same water holding capacity. In reality, sugar maple stands a few hundred miles from the prairie-forest border, in the interior of the forest biome, are responding more to increased drought frequency than those right at the prairie-forest border, because many such stands are growing on sandy soils, while the stands near the prairie are growing on deep silty soils on north facing slopes.
With regard to the north south gradient, I think sugar maple will respond to a warmer climate the way most trees have in the past: stands at the northern edge of the range are limited by cold temperatures; therefore a warmer climate will make them grow faster. Stands near the southern edge of the range are limited by a combination of warm temperatures and competition from other species that use a warm climate more efficiently, often growing taller, given the same soil conditions. Therefore, a warmer climate will put the species at a disadvantage. This is the driving force behind tree migration, north and south as the climate warms and cools. The previously mentioned latitudinal ecotypes within the species create the same dynamics among sugar maple populations (i.e. each ecotype will displace others currently to their north, and retreat due to oncoming more warm climate adapted ecotypes from the south). Lee DON BERTOLETTE wrote: > Lee- > What's your take on 'gradient analysis', as applied to the 'sugar > maple ecosystem', which from my understanding would suggest that the > sugar maple stands located at the most extreme extents > (geographically) would be the first to be impacted by multi-year > droughts, and other climatic inputs? > -Don > > > Date: Wed, 8 Apr 2009 08:56:11 -0500 > > From: [email protected] > > To: [email protected] > > Subject: [ENTS] Re: All tapped out. — The Daily Climate > > > > > > Russ: > > > > There are several causes of sugar maple decline. Multi-year droughts > are > > always a problem wherever they occur within the range of the species. > > Acid rain on certain soil types, leading to calcium deficiency can also > > contribute. In the north, European earthworm invasion is one of the > main > > causes of decline. The worms make the soil more dense, warmer, drier > and > > more nutrient poor (Phosphorous cycling is disrupted by earthworms and > > apparently this contributes to sugar maple decline). All of these > > changes in the ecosystem exacerbate the impacts of droughts, and also > > will reinforce the impacts of a changing climate. We have a study in > > review that shows a 30% decline in sugar maple ring widths due to > > earthworm invasion. > > > > Sugar maple (like most tree species) has strong ecotypic > differentiation > > by latitude, which does make it vulnerable to climate change. In other > > words, local populations of sugar maple cannot tolerate the range of > > conditions the species as a whole can withstand, so even a modest > > northward shift in range of the species will put all populations out of > > sync with the climate. > > > > I don't think sugar maple is going to go extinct, but its niche within > > its current range is likely to be reduced by all these factors. > > > > Lee > > > > [email protected] wrote: > > > ENTS: > > > > > > I'm not certain about the pending extinction of sugar maple. It is an > > > extremely common tree in areas far south of New England and most > > > generally the trees appear to be healthy. Because we are closer to > > > the sources of acid deposition and pollution from coal fired power > > > plants that are causing great harm the north woods I would at least > > > want to consider that air pollution rather than climate change is a > > > major factor in northern sugar maple decline. > > > > > > Russ > > > > > > > ------------------------------------------------------------------------ > > > Feeling the pinch at the grocery store? Make dinner for $10 or less > > > <http://food.aol.com/frugal-feasts?ncid=emlcntusfood00000001>. > > > > > > > > > > --~--~---------~--~----~------------~-------~--~----~ 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] -~----------~----~----~----~------~----~------~--~---
