Red Deer Rising
By Robert C. Balling Jr.,
Arizona State University
We listen for their hoofbeats on our
rooftops. But come Christmas morning, we dont give them another thought. Where do
they go? What do they eat? Is there enough to go around? How will elevated carbon dioxide
(CO2) levels affect where and how they live?
All year long, Santas reindeer
and their Northern Hemispheric colleagues must forage for food, battling low temperatures
in their struggle to survive. Happily, the scientific literature consistently reveals
that, whether temperatures warm or not, elevated CO2 will have a direct,
positive effect on the high latitude ecosystems and, consequently, their inhabitants.
Consider, for example, this
comforting news about one of our favorite holiday-season animalsthe famed red deer
of Norway. In a recent issue of Oecologia, scientists at the Norwegian Institute
for Nature Research reveal the benefits of the changing ecosystems affect on these
To begin, the authors note that red
deer populations have increased steadily over the last few decades for a variety of
reasons. Thanks to a rather aggressive capture-mark-recapture strategy in Norway, a unique
database is emerging on these wondrous animals, allowing for analyses of many factors
impacting their health and survival.
In this investigation, data for 678
individual animals were used to assess growth and survival rates and their association
with winter and spring weather, as well as sex, age, population size, body condition, and
body weight (in the world of red deer, as in the world of automobiles, small is dangerous,
whereas big may ensure your survival.) Using statistical techniques, the authors were able
to isolate the influence of each variable on the red deer population.
One thing they discovered is that red
deer simply cannot warm up to those cold winters of northern Norway! Winter harshness acts
as a limiting factor on population growth: In the short-term, it limits first-year
survival. In the long-term, it diminishes body weight and condition.
Global climate change, then, bodes
well for the red deer. As WCR readers are aware, winter temperatures may indeed be
increasing over selected land areas of the Northern Hemisphere. From what we learn in this
study, the red deer in Norway can be thrilled about the trend!
Obviously, more high-latitude deer
mean more demand for plants to eatsomething the northern latitude animal population
can count on, as two recent articles prove.
Tjoelker and colleagues examined
seedlings of five boreal tree species (quaking aspen, paper birch, tamarack, black spruce
and jack pine) grown in controlled-environment chambers for three months at 370 parts per
million (ppm) and 580 ppm atmospheric CO2. This 57 percent elevation of CO2
increased the seedlings photosynthesis by about 28 percent, while water-use
efficiencies increased by 40 percent to 80 percent. The jack pine seedlings, too, showed a
further increase in photosynthesis when the day/night temperatures were raised by a few
degrees. Increased CO2, and to a lesser extent increased temperature, combined
to enhance the biomass production of all five species. And thats good eatin if
youre a hungry red deer hoping to bulk up for safety.
A second study, by four German
scientists, appeared in a recent issue of Arctic and Alpine Research that will have
high latitude animals shouting from the rooftops (if there were any rooftops up there,
that is). In it, Lange and colleagues examined seven lichen species in Alaska, and they
measured in-field CO2 exchanges and photosynthetic rates (did you know that 8
percent of the earths terrestrial surface has lichens as the dominant life form?).
Among many other interesting
findings, the scientists tracked a strong linear relationship between net photosynthesis
rates and carbon uptake in the lichens. Although not a focus of their study, the results
show us that increased atmospheric CO2 should lead to increased photosynthesis
and increased lichen biomass in the future.
So the red deer will thrive. CO2
increases will stimulate growth in a variety of species, including those high-latitude
plant varieties of special interest to these Norwegian icons. Slightly higher temperatures
only compound the benefits.
Somehow, it seems a shame that up the
red deer of Norway, the five boreal tree species, and the seven types of lichen cannot
vote on international policies aimed at reducing emission of CO2. Perhaps they,
more than any of us, understand whats at stake here.
Lange, O.L., at al.
1998, Upland tundra in the foothills of the Brooks Range, Alaska, U.S.A.: Lichen long-term
photosynthetic CO2 uptake and net carbon gain. Arctic and Alpine Research, 30,
Loison, A. and R.
Langvatn, 1998, Short- and long-term effects of winter and spring weather on growth and
survival or red deer in Norway. Oecologia, 116, 489500.
M.G., et al., 1998, Seedlings of five boreal tree species differ in acclimation of net
photosynthesis to elevated CO2 and temperature. Tree Physiology, 18,