Dave Polster, plant ecologist
Monday, June 1, 2020
Posted by: Laura Capponi
Dave Polster is a plant ecologist with 40 years experience in vegetation studies, reclamation and invasive species management and leads his own consulting firm in British Columbia, Canada. He became a lifetime member in 2019. SER would like to extend a special thank you to David for his years of service on the SER Board of Directors. We are incredibly grateful for all that he has done for SER and for the field of ecological restoration. We reached out to Dave to hear how he got started in the field, what his career path has been like, and to learn about some of his favorite projects.
“I started my career in ecological restoration with my undergraduate thesis on the vegetation of talus slopes as these are ecologically similar to mine waste dumps. This interest carried on with my graduate studies of the vegetation of alpine areas in Southeastern British Columbia where industry was taking the tops off local mountains to mine coal with no idea about how to restore these sites. By understanding the way natural systems have evolved over millions of years to “restore” natural disturbances, we can understand how to look at human disturbed ecosystems in the same way. Taking lessons from nature, these drastically disturbed sites can be effectively restored, often at much lower cost than traditional treatments.
Working on the restoration of drastically disturbed sites has provided interesting challenges. Traditionally, large mine sites would be seeded with agronomic grasses and legumes. In 1977 I was asked to restore exploration disturbances at the forested site of a proposed 4 million ton/year coal mine site (drill pads, roads and trenches). I designed a seed mix (balanced by weight of the seeds so it was not dominated by small seeded species) and organized a helicopter to carry the seeding bucket and seed the disturbances to control erosion. In 2017 I had the opportunity revisit this area. Unfortunately, the agronomic grasses and legumes I used in the mix have occupied the disturbed sites since that time. The sites that I had seeded in 1977 were still covered by grasses and legumes with no forest species moving in. This is also a reminder of how much the knowledge about effective restoration, has changed over the course of my career – both for me personally and within the overall restoration field.
We needed to develop of an erosion controlling treatment that did not block the recovery of the site. so I studied erosion processes. I realized that erosion was composed of a number of different actions including things like rain drops interacting with small particles of substrates that I could do nothing about. But erosion is also related to water running across the surface of the ground and this was something that I could change. Making sites rough and loose prevents water from running across the ground allowing it to soak in to re-charge groundwater systems. In addition, the role of woody debris on forest floor is critical for some species. Making sites rough and loose and adding woody debris was a treatment I developed through my experiences, trial and error, and adaptive management.
When I was asked to restore a former dam site (see photographs) I decided to make it rough and loose and add woody debris. As this dam was partly located in a Provincial Park, and park managers had concerns about the outcome of this restoration strategy, I was asked to monitor the site for five years to ensure recovery. This provided a large volume of data that showed not only that the rough and loose approach, with woody debris-controlled erosion, but it also created a diversity of conditions that in turn led to a diversity of species establishing. While the pioneering species Red Alder (Alnus rubra Bong.) dominated, the overall project achieved over 50 percent cover, made up of more than 84 species, including 5 different conifer species in 49 out of 50 plots. In addition, 11 different fruit bearing plants (Thimbleberry, Rubus parviflorus Nutt., Salmonberry, Rubus spectabilis Pursh, etc.) self-established in 49 out of the 50 plots. None of these fruiting plants were planted; they were all volunteers, at no cost! When we think about the definition of ecological restoration as being “the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed” you can see how the rough and loose approach works with nature to jump start recovery!
Ecological restoration is a career that is both fulfilling and provides a benefit to the world. Adding in the use of soil bioengineering for the treatment of extreme sites has generated challenges as well as opportunities to explore the use of pioneering species (willows) to support failing sites and to initiate successional processes. Understanding the ecology of the sites that are being restored allows treatments to be tailored to the conditions of the site.”