Over the past few years, there has been concern expressed by the public, Department of Fisheries and Oceans, and environmental NGO’s over the relative lack of protection afforded to small streams during logging, where logging can occur up to the edge of small fish bearing streams. One of the most immediate impacts on small streams from this type of logging practice is the loss of shade and allochthonous input (needles, leaves, branches, bark, etc.).

Allochthonous input is considered an important nutrient and food source for invertebrates, which in turn are considered an important food source for rearing salmon and trout. Streamside vegetation also provides shade to small streams helping regulate water temperatures, stabilzes creek banks preventing erosion, regulates ground water levels and provides an important vegetated corridor for a diversity of species.  

Since 2003, Central Westcoast Forest Society has been annually monitoring allochthonous material (leaf litter) that is naturally introduced into small streams under different harvesting regimes and age classes. The purpose of this project is to quantify the relationship between allochthonous input and riparian characteristics to better understand the implications of riparian forest management.

Parameters that we monitor are allochthonous mass (g) that is naturally introduced vertically into small streams, nutrient content (nitrogen, phosphorous, and potassium (mg)) and composition (mass of wood, needles, cones, leaves and other organic material (g)). There are eleven small streams coastal temperate rainforest in Clayoquot Sound that have 10 litter traps placed along them. Each year field technicians collect litter trap samples, water samples and measure water quality paramenters.

This year we are bringing the project to completion partially due to funding cutbacks but also because we have enough data (years and samples) to make the results statistically significant. In January 2013, the field technicians dismantled and collected research equipment and the last litter and water samples. For more information on the importance of allochthonous material to stream systems and on why small streams are significant read the 2010/2011 Report.

Monitoring Allochthonous Input.pdf

Check out the CWFS Facebook page and to find photographs of the field crew taking the water samples and collecting the litter traps in January 2013 and 'like' us to stay up-to-date in CWFS news.