Freegro® tree shelters have proven to increase survival rates and accelerated growth for a wide varieties of tree species.

Click here to see trial result summaries:

Hybrid Poplar      Eastern Hardwood      Conifer

Hybrid Poplar Trials

Edmonton, Alberta, 2003 [click here for pictures]

A trial was set up by the Canadian Forest Service near Edmonton, Alberta at the end of June 2003. Short Freegro® shelters (90cm or less) were used. Preliminary mid-season comparisons between treatments (mesh types and heights) focussed on survival, early growth acceleration, windfirmness and browse prevention. All treatments greatly accelerated growth(>30cm per week). The average height of Freegro® treated stems was 1.2 m, while the average height of untreated (control) plants was roughly 40 cm. Survival and windfirmness values were more than satisfactory.

Boardman, Oregon, 2003 [click here for pictures]

At the end of April 2003, a trial was set up on an irrigated hybrid poplar plantation near the Columbia River in north-eastern Oregon. A variety of Freegro® shelters (different heights and mesh types/aperture size) were installed in a design that would allow for inter-treatment comparisons of survival, growth, self-pruning, browse prevention and windfirmness. Preliminary mid-season results showed height growth more than double the control. Self pruning appears to be effective on 2 of the clones tested. Browse protection and windfirmness performance were both more than satisfactory. Mid-season observations indicate that shorter shelter heights (<1.2m) would produce the best results and that shelters should be removed shortly after the tree has emerged (30cm to 60cm above). At the observed growth rates, this would occur between 4 to 6 weeks after installation. Each individual shelter could be re-used up to 6 to 8 times.

Fraser Valley, British Columbia, 2002 [click here for pictures]

In July 2002, a trial was set up in the Fraser Valley of British Columbia to determine the growth response of hybrid poplar cuttings (at Scott Paper site) protected/enhanced by Freegro® Fine Mesh and Exra-Fine Mesh shelters (15 cm diameter x 1.2 m. height). Shelters were moved up 30 cm later in the growing season to 1.5 m. in height. Virtually all the unrooted cuttings emerged above the 1.5 m. height with the average height at the end of the growing season being roughly 2.0 meters. Protected trees grew at a rate of approximately 30 cm (1 foot) per week up to the point they emerged from the shelter. The overall growth response would have been substantially greater if the shelters had been installed concurrently to planting (early May). Growth and vigour were markedly better than unbrowsed controls (heights in the 50 cm-100 cm range). Shelters will be removed just before the beginning of growing season #2. They will be re-used repeatedly (7-8 times). The added protection/growth enhancement costs are roughly equal to the savings (whips vs cuttings reduced plant handling and shipping costs, and reduced vegetation management costs), but the result is far superior. Both stocking levels (stem/ha) and growth will be higher, resulting in better yields (m3/ha) and shorter optimum economic rotations. Another important advantage observed was the absence of lateral branch development. Having a lower bole clear of branches is an important benefit when managing plantations for solid wood end products (pruning costs are greatly reduced). [top]

Eastern Hardwood Trials [click here for pictures]

The first Freegro® tree shelters targeting eastern hardwoods were set up in two regions of Quebec in the spring of 2000. Six species were included in the trials. The results have been very positive. With red oak and silver maple, a significant growth response was observed at the end of the first growing season. By the end of the second growing season, all protected species were showing height increments significantly higher than controls. Survival rates and seedling vigour were also much better for Freegro® protected stock. Most protected seedlings had emerged from 1.2 and 1.5 meter high Freegro® tree shelter by the end of the second growing season. The most significant growth response observed was with red oak, with heights ranging from 1.4 to 3.0 meters. There was minimal damage observed, nor was there any significant shelter displacement due to wind, snow or animal browse. No die back or dessication problem was observed. Follow up trials have been established at five Ontario and New York states sites. Similar results have been observed at these sites. The only major problem observed was herbaceous weed competition choking out seedlings in a small percentage of protected trees. This can be avoided by minimal micro-site preparation and/or the application of mulch.

Freegro® tree shelters have proven effective in preventing animal damage while enhancing growth at a level which allows vulnerable hardwoods a chance to quickly grow above browse heights and competing vegetation. With certain species, this can be accomplished without the use of pre-emergent herbicides. [top]

Conifer Trials [click here for pictures]

Several conifer browse protection/growth enhancement comparative trials have been established on the Pacific Coast of North America since 1999. Given the rapid evolution of Freegro® tree shelter designs, performance results of 2001 and 2002 trials have been considerably better than those observed in the 1999 ‘proof of concept’ trials or even the first operational trials carried out in 2000.

In general, the two main coastal coniferous species requiring protection, red cedar and Douglas fir, have responded well to altered growing conditions inside Freegro® tree shelters. Height increments observed have been similar to adjacent plastic tube-like shelter treatments. In large operational trials Freegro® models were compared to the main ‘tube-like’ shelter models used on the British Columbia coast. On good sites, most Freegro® protected trees had emerged from 90 cm and/or 1.2 m. high shelters after two growing seasons. On medium to poor sites, emergence above the 1.2 meter height occurs after three to four growing seasons. Initial problems of wind firmness observed in 1999 and 2000 trials brought about design changes. These modifications have produced much better wind firmness results (> 95% firm) in 2001 and 2002. Installation productivity has improved as well. In 2001 and 2002, experienced crews were capable of installing over 300 shelters per person day, with some crew averages approaching 400 units per person day.

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