Ecological integrity in the Park Drive Ravine_1977 to 2015
Anqi Dong, Master of Forest Conservation
Ecological integrity is an important concept in ecosystem management. It is a measure of ecosystem health, and the abundance and functionality of native species are the key components. The main objective of this study is to obtain estimates of the ecosystem health of the Park Drive Ravine, Toronto, Ontario, Canada through the lens of ecosystem health. A comprehensive survey was conducted in the Park Drive Ravine in 1977, and a canopy resurvey was conducted in 2015. Results indicated a degraded ecological integrity in this ravine – the relative contribution of native species has decreased with no or little evidence of regeneration, but the relative contribution of non-native species, especially Norway maple (Acer platanoides L.) has increased with lots of regeneration. Ash species (Fraxinus spp.) and American beech (Fagus grandifolia Ehrh.) used to be two of the dominant species in this ravine in 1977, but their populations have largely declined due to the massive infestation of emerald ash borer and beech bark disease. As the ravine canopy loses these major contributors and other native species, the population of Norway maple will further expand and severely degrade the ecological integrity. In order to restore the ravine ecosystem, long-term monitoring of various taxonomic groups in the ravines is recommended, and collaboration among various stakeholders is critical.
Awarded the Fred G. Jackson Prize for best Master’s Thesis 2015
A Protocol for Seed Forecasting Oaks in the Toronto Ravines
Jane Michener, Master of Forest Conservation
The City of Toronto has been described as, “a city within a park” because of its extensive ravine system; they make up 17% of the urban landscape encompassing over 11,000 thousand hectares. Recent studies have shown that there is limited to no native regeneration occurring in the ravines while non-native species are thriving, this makes it important to identify native seed trees within the ravine ecosystem in order to begin implementing artificial regeneration. The aim of this study is to set up seed forecasting protocols for native Quercus spp. within six ravines by identifying and mapping Quercus trees species on public property with a DBH of >50cm and setting up specific seed forecasting protocols that examine the acorn yield of the whole tree in the crown and on the ground. One hundred and twenty eight Quercus species were identified of the subspecies Erythrobalanu and Leptobalanus: 107 Quercus rubra, 20 Quercus alba and 1 Quercus marcrocarpa. Seed forecasting was preformed the last two weeks of August and from Sept 10th-21st and all three species, Quercus rubra, Quercus alba and Quercus marcrocarpa experienced crop failures with no acorns detected in the crown and on the ground. First year acorn measurements on the terminal branches of Erythrobalan were conducted in October and November within five of the ravines in order to assess the potential acorn yield for 2017. We found an average of 1.04 acorns per branch indicating that next year’s acorn crop will also be a failure. These finding highlight the importance of having a set database and seed forecasting protocols for Quercus spp. within the ravines to monitor acorn production and assist in artificial regeneration.