b'RESEARCH AND DEVELOPMENT40YEARS LATERBy Warren HeeleyA novel study on a gravel pit rehabilitated four decades ago sheds light on the need for native species and ongoing maintenanceI n2018,TheOntarioAggregateResourcesCorporationexist at the gravel pit compared to Victoria Woods. While appearing (TOARC)partneredwiththeUniversityofGuelphpositive at the outset, this could be the result of a more balanced plant Arboretumtostudya40-year-oldrehabilitatedgravelpitcommunityintheWoodsthatisconsumingallofthesenutrients on the universitys Arboretum land. The findings, publishedleaving very little in the soil samples.this past March, were revealing.Inventories of the woody plant species showed that 53 of theSomewhat discouraging was that invasive species made up the top 90 species originally planted had survived and 41 of these speciesspecies found in the pit; however, this was also understandable given that some were included in the original plantings. showed signs of self-generation and expansion beyond the original planting area. A number of the large trees originally planted hadIn certain cases, the invasive species were planted as a part of the grown well and made up the current upper canopy in the gravel pit. original rehab work as they would have been considered best practices at that time, states Danielle Solondz, program manager at TOARC. In terms of soil samples collected from the pit area and VictoriaOther species simply invaded the site. The study determined that the Woods, an old-growth forest beside it, researchers discovered thattop five species found in the pit were invasive, but it should be noted that higher values of key plant nutrients (phosphorous and potassium)these species are common in any ecosystem if not removed manually.Today the rehabilitated Arboretum site is covered with a varied mix of woody plant species'