Conserving the heritage landscape – Tree Management

Severe windstorms over the last six months have caused damage and destruction of aged trees at Parkwood.  Grounds Foreman Brad Beer and Curator Samantha George recently grappled with various tree issues, and with the advice of City of Oshawa Forestry Supervisor Rob Fennell, have identified Parkwood’s  TOP TEN TREE PROJECTS.

Parkwood has some incredible trees, many of which were already here when Sam McLaughlin purchased the property in 1915 to build his dream home.  Working with top garden designers over the next 20 years Sam and his wife Adelaide then planted many more trees – to achieve the complex compositions and layered views we enjoy today.  Most have reached a venerable age and beauty that you just can’t find elsewhere.

Sadly, like us, trees can age gracefully or quickly lose their looks and faculties, move into a slow or a rapid decline.  The plug must be pulled at some point.

Trees are part of Parkwood’s overall heritage conservation, an interesting and challenging process that includes:

Collections Management & Curatorial

Trees are considered in the same way that the mansion, furnishings and archives are - catalogued, monitored, with threats identified and addressed if possible through conservation “spa” treatment.  Trees are researched individually and as part of the design, social and family histories of Parkwood, for interpretation and educational purposes (eg. tree walks, garden tours, lectures, future virtual).  

Evaluation/Assessment

Trees are assessed with regard to overall health and appearance.  Treatments are devised to improve health and increase life-span (root feeding, pruning/thinning, cabling, pest management)

Risk assessment is an important factor, to ensure the safety of garden visitors, staff and volunteers.

Removal becomes necessary at some point, and planned according to urgency and equipment access.  Late winter often provides the best opportunity for tree work, with frozen ground and leafless trees.

 

Replacement

Research and site assessment is undertaken to determine if replacement is desired or possible.  Heritage conservation dictates replacing like with like, which is always our preference but not always possible.

The replacement trees are chosen by species are size, taking into account the location, season, time frame to do the work, and equipment access (eg. tree spade or truck) and of course COST!

Site preparation is undertaken to provide the best head start for new trees.

Funding Tree Management

It’s always a challenge to find the operating and capital support needed, with so many heritage resources and competing priorities at Parkwood.   Effective tree management requires a sustained effort, which isn’t always possible.  Parkwood is grateful for individuals and businesses who provide generous assistance.

 

Tribute/memorial planting

Generally, Parkwood plants trees strictly within the context of historic replacement.  We maintain lists of historic varieties/priorities for replacement, to respond to donor requests to plant trees to mark occasions or in tribute/memorial.

Once in a while a unique opportunity arises.  In 2011 Finance Minister Jim Flaherty and Landscape Ontario planted a native maple tree, the first tree planted to mark the first National Tree Day in Canada.  This took place in a non-historic space (altered in the 1970’s for the parking garage), so was a happy exception.  Do try this at home!  The next National Tree Day is Sept 25, 2013.   

Tree Selection process

Parkwood adheres to landscape conservation principles of the Standards and Guidelines for the Conservation of Historic Places in Canada, which address land patterns, landforms, spatial organization, vegetation, viewscapes, circulation, water features, built features.  Many of these guide or inform tree replacement selection, to which factors we add Parkwood’s particular history.

The Dunington Grubbs Landscape Architects

Historic & Design considerations: 

 

·         What inspired the choice of species and placement originally?

 

·         What were the original design considerations, characteristics and functions, we want to respect (eg. size and form within the treescape, colour and texture of leaves & bark, intended to blend or contrast with neighbouring trees)?

·         Was the tree a particular favourite of Sam or Adelaide, a gift to them, planted to mark an anniversary or occasion?

Site Conditions Then & Now

·         Are there site conditions that contributed to the failure/decline of the tree (sunlight, moisture)?  Can they be remedied so that a replacement can flourish?  If not, do we reconsider the replacement? Do we delay replacement for years or decades?

·         Would you replace a Dutch Elm or other disease-prone species? 

 

 

Parkwood National Historic Site

TOP TEN TREE PROJECTS

 

Parkwood acknowledges with appreciation the advice of City of Oshawa Forestry Supervisor Rob Fennell.

1.      WHITE SPRUCE Location:         North End of Arbour Action:             Remove to ground level and clean up/dispose of all brush Replacement:  Not advised at this time	Cost:$ 2,000
2.      SILVER MAPLE Location:         South Lawn, along Terrace                           walkway Action:             Deadwood prune and remove all stubs and hangers;                                 clean up/disposal of all brush	Cost:$    300
3.      SIBERIAN ELM  Location:         3  trees - Rose Garden, 2 trees – South Lawn Action:              Remove trees in Rose Garden to ground level, clean up &                           dispose of all  brush, plant and stake new Replacement: 80mm caliper Siberian Elm (3 to Rose Garden, 2 to South                           Lawn, per previous storm damage/removal)	Cost:  removal              $6,000               replacements    $ 1,000
4.      SILVER MAPLE Location:         Border planting area along Simcoe Street fence Action:             Remove to ground, clean up/dispose all brush  Replacement:  Not advised at this time	Cost:$ 1,500
5.      SCHWEDLAR MAPLE Location:         South Lawn Action:              Remove to ground, clean up/disposal, grind stump  Replacement:  15’ to 18’ improved Schwedlar variety	Cost:  removal $ 4,500                replacement  unknown
6.      SILVER FIR Location:         Main Entrance driveway Action:              Remove to ground, clean up/dispose of all brush Replacement:  Not advised at this time	Cost: $ 300
7.      BASSWOOD Location:         Main Entrance driveway Action:              Remove old trunk to ground, clean up/dispose of all brush Replacement:  Not advised at this time	Cost: $ 300
8.       RED OAK Location:         South Lawn Action:              Deadwood prune, clean up/disposal of all brush	Cost: $ 700
9.      CEDAR & WHITE SPRUCE Location:         South Lawn, east of Summer House Action:              Removal to ground,  clean up/dispose of all brush                            3 Cedars & 1 White Spruce Replacement:  Not advised at this time	Cost: $ 400
10. WEEPING ASH Location:         South Lawn Action:              Deadwood prune, clean up/dispose of all brush	Cost: $300
TOTAL ESTIMATED COST                                                         $ 17,300