The arrival of spring has us all eagerly awaiting an abundance of sunshine. But rainy weather is the default mode around here. That's because we live in a rainforest.
This year is the United Nations Year of the Forest, which makes it an appropriate time to reflect on what a marvellous place on the planet this is. Yes, we get rain but all that wet weather can create fantastic rainforests, ones we tend to take for granted.
When most people think about rainforests, they typically imagine a lush tropical jungle full of vines and spectacular wildlife. It's true that tropical rainforests provide habitat for over half of all the land-based species on the planet even though these forests comprise only 12% of the earth's total forest cover.
But temperate rainforests such as ours are valuable and unique in their own ways. They exist in only the few places that have sufficiently high rainfall. This usually requires proximity to an ocean, where moisture-laden clouds are blown into mountains that then wring the rain out the clouds.
Temperate rain forests are characterized as forests with annual rainfall from 85 to more than 500 cm. South of the equator, temperate rain forests grow along the west coast of South America and in New Zealand and Tasmania. In the northern hemisphere, temperate rainforests are sparsely distributed in mountainous regions of Japan and Norway but are found mainly along the Pacific west coast from northern California to Alaska. Once, smaller and less wet rainforests grew in parts of Ireland, northern England and Scotland but these are now, except for a few remnants, long vanished to meet the needs of civilization.
The northern Pacific coast receives prodigious amounts of rain - up to 4 m or more in places - and supports such expansive temperate rainforests that they account for more than a third of all such forests in the world. In B.C., our rainforests can be loosely defined as where western hemlock and western red cedar grow.
Look out your window: You are likely to see some of these trees trying valiantly to recreate a rainforest in what are now suburbs.
Further south, in northern California, the majestic redwoods, which rely more on fog than rain for moisture, mark the southern limit of the Pacific temperate rainforest belt. In Alaska, mountain hemlock and yellow cedar are the predominant rainforest trees at sea level in northern extremes.
Temperate rainforests, which account for just 2% of the world's forests, don't support nearly as many species as do tropical rainforests but they are especially rich in mosses and lichens.
Our rainforests also support some of the tallest trees - up to 70 m, whereas the tallest trees in tropical rainforest reach only 50 m.
Our temperate rainforests are highly productive ecosystems with a dense understory of deciduous shrubs, herbaceous plants, an abundance of woody debris plus a thick cover of mosses, lichens and ferns. Our coastal rainforests are also extraordinarily rich in plants that live high in the forest canopy along with a number of invertebrates.
Through their ability to nourish young salmon in forest streams, the temperate rainforests also have a unique relationship with the marine environment. In return, up to 80% of the annual nitrogen uptake in ancient rainforest trees comes from nutrients derived from the rotting bodies of spawned-out salmon.
Biomass - that's the weight of all living material - is truly exceptional in temperate rainforests; it can exceed 2,000 tonnes per hectare and far outweighs that in tropical forests, which have biomasses that rarely reach 250 tonnes per hectare. This means that when temperate rainforests are logged, tremendous amounts of carbon are released not only from the trees but also the understory and soil.
In terms of carbon dioxide emissions, deforestation is second only to the burning of fossil fuels when it comes to accounting for our greenhouse gas emissions. Sadly, already half of the world's temperate rainforests have been logged.
While the Great Bear Rainforest and offshore Haida Gwaii comprise one of the few remaining large areas of relatively unmodified temperate rainforests on the planet, we do have fragments of protected rainforest a little closer to home. Each summer, Metro Vancouver offers watershed tours into the Capilano, Seymour and Coquitlam forests from which our drinking water is derived. Some of these tours offer opportunities for short hikes into areas of old-growth forest. If you want to explore a rainforest, these tours offer a quick day trip to the very special rainforest in our backyard. (Closer to summer, visit www.metrovancouver.org for details and schedules of such tours.)
Elaine Golds is a Port Moody environmentalist who is vice-president of Burke Mountain Naturalists, chair of the Colony Farm Park Association and past president of the PoMo Ecological Society.
