Technology for Improved Tree Liner Production in Ontario, Canada

As natural forest ecosystems are declining, more emphasis is being placed on the urban forest for tree-given benefits such as carbon sequestration, fine-particle filtering and noxious compound removal. Trees maximize their utility after 30 years of age, however in the urban environment the average life span for a tree is 10 years therefore increasing survival of trees through improved stock is necessary for maintaining the urban forest. Eleven different species from 8 genuses (Acer, Betula, Celtis, Cercis, Gleditsia, Quercus, Robinia and Syringa) were planted in spring of 2009 at the Vineland Research and Innovation Centre in a retractable roof greenhouse (RRG), which was programmed to open between the temperatures of 10° and 26.6° C. GeoHumus (GeoHumus International GmbH & Co. KG, Frankfurt, Germany) a substance that retains water and degrades over 3-5 years was added to the substrate in 0, ½, 1, and 2% additions by volume. Additionally, Betula X ‘White Satin', Syringa, Acer freemannii ‘Firefall', and Robinia were chosen for a transplant study and were planted directly into a #3 container or were put in air-pruning Elle pots (A.M.A. Plastics, Kingsville, ON) grown for one month then transplanted into #3 containers. All the remaining species were planted into #3 containers and grown for 20 weeks. Three randomly selected plants per species per production environment were monitored. In September caliper, height, and leaf areas using Model Li-3100 leaf area meter (LiCor Inc., Lincoln, NE) were taken. One randomly selected tree per rep and species was selected for leaf area and dry weight measurements. Generally the 2% GeoHumus addition yielded plants with a greater caliper, but this trend was not consistent in all the species. Air pruning Elle pots improved growth in Betula and Robinia, but Acer was best grown in a #3 pot.