Karen Iwachow.
Over the winter and spring of 2018 Camosun College Environmental Technology students Karen, Katie and Patrick surveyed the trees, mosses and herb species in their Galiano Island study site. You can bet they know what is in every square meter of that site! Karen still dreams about counting Oregon beaked-moss. The researchers conducted surveys to determine if the land owners’ eco-forestry based treatments are having an effect on the biodiversity (species richness) of his forest stands.
Coastal Douglas-fir ecosystems have been in decline since the early 20th century as a result of industrial scale logging in addition to fragmentation from urban developments. At present only 2% of all Coastal Douglas-fir ecosystems exist to their original extent and of that only 0.5% is original old growth. Those statistics make this ecosystem the most endangered in British Columbia. Galiano Island has been devastated by logging. Over 50% of the island was clear-cut logged; today about 6000 ha of forests are recovering from that logging. The conservation minded community on Galiano Island has been successful in protecting about 14% of their forests.
Karen Iwachow.
Forests managed for timber are raised differently from the way forests grow naturally. Managed forests are intentionally planted with fast-growing and disease-resistant trees such as coastal Douglas-fir for quick harvests. These trees are ready to cut at around 60 – 80 years of age. For these managed forests, biodiversity is second in importance to quality timber. When the timber companies left Galiano in the 1980s many of the remaining forests were these managed plantations. The land that the study site is on was purchased by the land owner in 1993 and he described the land as bare rock with young Douglas-fir saplings. Since then he has been treating the forest with methods intending to promote growth and species richness. Thinning trees and pruning lower branches reduces canopy cover and density to increase the amount of sunlight reaching the forest floor; this allows light and space dependent understory flora to thrive.
So, are these methods working? Future research will tell, but indications say, yes.
The team compared three sites; a mature stand (around 100 years old), a stand with thinning and pruning treatments, and a stand with no treatments at all. The latter two were planted at the same time and the stand age was determined to be around 35 years of age. The team determined that the reduction in canopy density created by thinning did influence how fast the trees were growing. Accelerated growth appeared to be a response to less competition for nutrients and sunlight. The diversity present in the treated and untreated plot was similar to the mature stand. Given that the forest recently experienced disturbance by clear-cutting and burning, regenerating a biodiverse forest would be a struggle. It is likely that the soils washed away after the logging and along with it the bud and seed banks. We know that species reintroduction in an area is related to ecosystem elements such as vegetation structure and existing species populations. In order for a species to return to an area there must be available and functioning habitat for them to thrive in. With understory species being shaded out by fast-growing Douglas-fir monocrops and seed banks having been lost through erosion, seed rain from nearby forests is necessary to provide ecosystem services to returning species. However, because 50% of nearby forests are recovering from the same fate, seed rains are limited in species richness.
Karen Iwachow.
Other studies have shown over time that with similar treatments of thinning and pruning trees, leaving felled trees for nurse logs and wildlife trees, and planting native plant species there is a positive response in plant species diversity and increase in native wildlife presence. The treated study site which the students were looking at was still undergoing pruning treatments, and therefore still experiencing a disturbance. The team recommends returning to the site five years after the treatments are finished to survey the species and glean a greater understanding of the response to eco-forestry treatments.
Biodiversity provides many ecosystem services which contribute to resilient forests. Aside from their intrinsic values, preserving biodiversity reduces wildfire risk, increases air quality, increases water quality, increases carbon sink, reduces climate change impact and provides us with the refuge of nature. Studies like the one detailed here allow us to learn what techniques can improve the resilience of our forests so that future generations don’t have to speak about coastal Douglas-fir in the past tense but can rely on live and thriving forests. Conservation-minded land owners like those on Galiano Island are proof that our communities are interested in keeping these legacies alive. The site these students studied is not only experiencing restoration treatments but is also protected by a conservation covenant. With only 2% of coastal Douglas-fir forests remaining intact, it is more important than ever to protect and restore these special places.
Karen Iwachow.
This study gives TLC some guidelines for other forest restoration projects and also provides hope that it is possible to not only conserve an important area but also to restore damaged systems and promote biodiversity which is key to ecological health. Moreover, this study has illustrated the way that conservation-minded landowners are significant allies in restoration practices. In light of disastrous and destructive development across the province, restoration must be a focus in order to ensure that BC’s treasured landscapes and habitats will exist into the future. Conserving land does not end with the act of placing a conservation covenant, the stewardship of that land as wildlife habitat, forest, or other complex ecological system is equally significant.
Learn more about conservation covenants and TLC’s restoration work here. See Part 1 of the Galiano Island Biodiversity Study here.
