Since moving to Thetis Island I have become a big supporter of hugelkultur (mound cultivation). The first attraction to me was the way it extended the carbon cycle, but other benefits soon became clear.
Hugelkultur starts with logs or large branches. These make up 30% of the mound. Dead logs will naturally decompose and the carbon will return to the atmosphere, traditionally with a tree the carbon is gone in about 10 years. So by burying the log makes the carbon journey to the atmosphere a little more difficult, often working through many life forms along the way. Extending the carbon cycle reduces the rate of carbon going into the atmosphere.
As I researched hugelkultur I found there are a number of benefits to the garden. As the logs decompose they hold water, they give off nutrients and they give off heat (extend the growing season). A mound garden also provides more surface area for planting. The many layers (from inside to out: logs, branches and leaves, compost/manure, original soil) provide opportunities to get rid of yard debris - basically if it is organic it is useful. On our island the traditional method of handling debris was to wait for fire season and burn it, while hugelkultur provides a more Earth friendly alternative. After 10 years the log has mostly decomposed and the mound is now high quality soil.
Climate change has affected BC's Southern Gulf Island in a big way already. Islands Trust studies show that we are expecting/getting 10% wetter winters and 10% drier summers. Flooding in the winter followed by arid summers that have already killed many of our cedar trees. Hugelkultur helps deal with the extremes. By placing mounds strategically, water flow can be interupted, allowing it to sink into the ground. Unfortunately it is unlikely that it will feed the water table, but it gives a longer opportunity for trees to store water in their vertical rivers. Log based mounds will also wick water up, creating vertical storage which preserves water for the dry summer. Tree debris is a fire hazard, however if it is combined with enough organic matter it will stay moist and will be firesafe. Hugelkultur is one of the many ways to be firesafe while maintaining our natural landscape.
Now when I hear of someone planning a debris fire, I offer to come and get their debris and I am building a list of neighbours that are looking to build mounds for their garden, as a privacy barrier or to help with water runoff. A drop in the bucket I know, but that is how a rain barrel fills, one drop at a time!
