I like to tell anyone who listens that growing up in the Pacific Northwest means I learned how to 'walk between the drops'. When heading outside on a rainy day my wife (from New England) will don a winter parka, grab an umbrella, and laugh lovingly at me as I head outside in my sweatshirt. You kinda learn to just live with the water in the left corner of the US. Yet we are also a unique corner of the world as far as temperate forests go. Our summers are warm and dry, while our winters are cool and wet, while in most temperate zone the rain falls all year long. Around these parts there are droughts in the middle of summer, lawns turn golden tan, and less tolerant plants wilt and die. Climate change experts predict that our summers will continue to get warmer and drier, and our winters will get warmer and wetter. All of this leaves me wondering, are we ready? When I look at the old growth forests of the Pacific Northwest that have been around for thousands of years I ask what can we learn from them? How might our buildings, landscapes, and cities perform like a native forest?
Epiphytes Among Us
If you hold still long enough out here moss will grow on you. Lichen, moss, and ferns sprout up out of sidewalks, walls, and roofs overnight. The forest is covered with a green blanket, and it turns out these epiphytes (things that live on trees) have a huge impact on the water system of the Pacific Northwest. During a short rain-storm, standing under a big Douglas Fir tree will keep you dry. The huge canopy and rampant epiphytes absorb the water that is falling from the sky. During a small rainstorm the water never reaches the ground.
The three dimensional structure of mosses even works better in big rainstorms. The sponge like structure dissipates the energy of the raindrops, in the process actually increasing their ability to hold more water. During a big rainstorm they hold more water! Contrast that with our urban environments. Instead of catching and slowing down water, we channel it into larger and larger pipes rushing it along (pollutants along with it) right into the Salish Sea- and our systems don't get better when it rains harder.
In a big Douglas Fir tree there will be more epiphytes toward the top of tree. Surprisingly, big branches higher up soak up more water. Scientists believe that where there is more opportunity for evaporation on a Douglas Fir, there tends to be more epiphytes. What if we had buildings capture and slow down water? What if where we had opportunity to evaporate we created ways to capture water? What if our urban environment could collect, evaporate, and improve water quality as part of how it was built?
Our challenge in creating a resilient water infrastructure is in better understanding the challenges and opportunities within our environments. By looking to the natural world around us, we can begin to gain insights into how we might build a future where we are as resilient as the forests around us.