5th July 2026 – Vale Dave Polster
Our SER section honors the life’s work of David Polster, who died on 11 May 2026, at the age of 74. (See SER’S tribute here.) A pioneering Canadian plant ecologist, restoration practitioner, and educator, David helped shape the science and practice of ecological restoration over more than four decades. He helped establish SER’s British Columbia Chapter, served on the SER Board, was an inaugural CERP recipient in 2019, and received SER’s John Rieger Award in 2013.
A generous educator and mentor, in 2020, he presented the SER webinar Natural Processes for the Restoration of Drastically Disturbed Sites, highlighting the approach that guided much of his life’s work.
Below is an excerpt of case study by David Polster published in the book Chapter: McDonald T, Chazdon R, Prach K, Tucker N, Venkataraman R, Graham L, Rinaudo T, Shono K, Polster D and Cook D (2023) ‘Using degree of natural regeneration potential to guide selection of plant community restoration approaches at a restoration site’. Pages 241-285 in: Florentine Singarayer, Gibson-Roy, Paul, and Dixon, Kingsley and Broadhurst Linda (2023) Ecological Restoration: Moving Forward Using Lessons Learned. Publisher: Springer Nature Switzerland.
“Box 7.4: Case Study 3. Using Natural Processes for Restoration After the Removal of Heber Dam, British Columbia, Canada.
The Heber River Diversion Dam (Heber Dam) on Vancouver Island, British Columbia, Canada, was removed in 2009 to return the flows in the Heber River to pre-dam conditions and restore the footprint of the dam and its 3 km pipeline. The restoration treatments were modelled on natural successional processes, harnessing natural colonisation. The recovery of dam and pipeline
removal disturbances was initiated in 2012 with the fall season dispersal of seeds from mature pioneering species that formed a significant part of the nearby local undisturbed vegetation.
As the barriers to natural recovery were compaction of substrates and a lack of micro-sites, works involved creating a rough and loose soil surface, with an array of mounds and holes to promote infiltration (avoiding erosion) and creating varied micro-sites for a diversity of species to establish. Large woody debris was added at a rate of 100 m3/ha. Commitments had been made to the Mowachaht/Muchalaht First Nation that they would be involved in the restoration work. A First Nation crew was hired to transplant about 1000 ferns which also brought in a host of soil micro-organisms.
Natural recovery processes led to an increase in plant species numbers from 32 to 84 species over five growing seasons (Polster, 2017) including five species of conifers, while the percent cover of the vegetation increased every year to 54% at the fifth year (Figs. 7.3 and 7.4). Red alder (Alnus rubra) trees had exceeded the agreed stocking rate (4500 stems/ha) and conifers and fruit-bearing plants were found in 98% of the 50 sampling plots. Early colonisation of red alder fixed nitrogen and provided a deciduous cover over the slower-growing conifers that ensured their protection during summer, while providing sufficient light for them to photosynthesise in winter. The cost of the restoration work has been significantly less than the cost of traditional reclamation treatments, such as tree planting, and the diversity of established species has been far greater than with such traditional treatments.
The density of red alder will reduce over coming decades and the understory vegetation will shift as the overstory changes and soils build over time on the relatively inert gravels. By allowing species composition and cover to be dictated by natural processes, diverse ecosystems appear to be establishing on the disturbed sites with every indication that this process will continue.
Fig. 7.3 July 2013. Dam area. Rough substrate of the disturbed area surrounded by stands
of red alder (Alnus rubra). (Photo David Polster)
Fig. 7.4 June 2017. Same area showing prolific regeneration of red alder along with 80
other species. The alder trees are starting to thin out while other species move in. (Photo
David Polster)”