Showing posts with label tree biology. Show all posts
Showing posts with label tree biology. Show all posts

Saturday, June 20, 2009

Never Mind Cars, Plant a Forest Within Cities and Without to Mitigate Global Warming

The Natural Fix: The Role of Ecosystems in Climate Mitigation is a new U.N. report identifying three ecosystems that are priorities in slowing down global climate change: tropical forests, peatlands, and agriculture. The report "recommends a 50 percent reduction rate in deforestation by 2050, and maintaining it until 2100, which equals 12 percent of the greenhouse gas emissions reductions needed to keep atmospheric concentrations of carbon below 450 parts per minute (ppm)."

Please note also: Activist groups issued a consensus statement about halting deforestation on June 9 at climate talks in Bonn, Germany. The consensus called for measures to be included in the Copenhagen protocol "to reduce consumption of forest products." The Copenhagen protocol should also exclude "any form of carbon offsetting," the statement said.

The emphasis here was on tropical forests, but BC's wilderness also preserves biodiversity, sinks carbon and produces oxygen. In urban areas, the heat-island effect of paving must be mitigated by maintaining comprehensive canopies, and leaving space for them by tailoring development rules accordingly.

Update: In his speech introducing the B.C. Government's new budget (Sept. 1st) the Minister of Finance says we will get out of our deficit situation next year by making huge increases in sales of forest products (to the American building market). In other words, we'll cut the forests down to boost the economy. Obviously, the Liberal Party of B.C. hasn't heard what the experts were saying at the Bonn climate change talks -- even though with their carbon tax on gas they pass themselves off as pro-active on global warming. The problem is that it is not the ordinary driver who is driving climate change, but the forest industry and the meat industry. Yet the B.C. Government actually supports and stimulates them.

Sunday, August 10, 2008

Trees and Weather

Trees are miraculous -- some of the most fundamental things about them are still unexplained by science. For instance, how does a tall mature cedar or Douglas fir -- over 300 feet tall -- transport water up its trunk against gravity? A combination of theories exist involving capillary action and evaporation creating a vacuum in xylem (which is made of tracheid columns), but the truth is we don't really understand many mysteries of the plant world. This mysteriousness is lyrically conveyed among many particular gems of information in David Suzuki's and Wyne Grady's short but comprehensive Tree: A Life Story.

A tree lifts and transpires vast amounts of water, they say, and then they go on to describe how forests (land plants having evolved from fungi which even earlier evolved from marine algae) make the hydrologic cycle:

"The (Amazon) rainforest behaves like a green ocean, transpiring water that rains upward ... mists flow across the continent (of S. America) in great rivers of vapor. The water condenses, falls as rain, and is pulled back up again through the trees. It rises and falls on its westward migration .. six times before finally hitting the Andes and flowing back across the continent as the mightiest river on Earth. Across the world, forests constantly replenish Earth's supply of fresh water and play a key role in weather and climate."

This teaches us how important it is to retain tree cover, even -- or especially -- in paved over urban regions -- so as to retain water, which in turn we need in order to retain trees. We destroy the cycle at our peril, since we too, and our food crops, cannot live without water.

There are other ways in which trees are exquisitely enmeshed with weather: in Borneo over 50 canopy tree species synchronously produce a mass of fruits and seeds every 3 to 7 years. Birds and animals rush to consume the seeds from the forest floor -- birds, orangutans, wild boars, and insects -- this sustanance coming from the fact that the El Nino southern oscillation had the previous year brought drought to the region. The bumper crop of seeds (called masting, which our Garry oaks also do in periodic acorn years) is an evolutionary strategy for compensating for the losses during the drought years.

Tiny songbirds also play their part in creating our huge temperate forests: driven by weather to fly south, they eat Douglas fir (and other) seeds on their journey, and then scatter them far and wide as they go, contributing to the range of the various tree species, which in turn changes the weather (see above how the forest maintains rain and mist), and even the patterns of wind.

And: "wind travelling over trees is different from wind travelling over naked soil," say Suzuki and Grady. We all have an image of the North American Depression dustbowl in our head. As human populations grow and suck up surrounding water, deserts spread on Earth -- much of the dust in our west coast air comes from deserts in China; in Europe it comes from North Africa. We have also most of us experienced the fierce wind tunnels created between city highrises. It behoves us to make sure that the tallest things in our cities are the trees: we destroy at our peril the wind, water and weather patterns vouchsafed to us by forests.