The Mighty Oak Needs You!

Issue: 
November-December 2008

A FRIEND CALLED LAST FALL and announced, “I planted an oak tree today.” “You’re feeling young?” I questioned. “No,” she replied. “It’s for my newest grandson. Perhaps his grandson will have a tire swing in it.” Planting an oak is a gift for tomorrow. We’ve loved it for flooring, kitchen cabinets and its magnificent shade. But our love affair with oak was self centred. We haven’t allowed it to regenerate, studied it or given it much attention at all. There is no emerald oak borer, oak rot or oak syndrome attacking our mighty oaks. Between a world war, depression/recession, the “now” generation and the “me” generation, oak was simply not a priority.

It is a good time to be growing oak again,” says Andree Morneault of North Bay, MNR. Andree and her colleagues are compiling best practice guidelines for oak in Ontario. They will be based on the combined knowledge of Ontario’s researchers and experimental data, with the goal of a December 2009 release.

According to Bill Parker of the Ontario Forest Research Institute, OFRI, “In central, eastern Ontario and the eastern US, the amount of red oak, whether in red oak dominated forests or other forest types, has declined over the past 50 to 100 years.”

Parker said, “During the period of European settlement, logging of pine forests and the use of fire to clear forests likely encouraged oak regeneration. More recently, fire suppression and the lack of information on how best to manage and regenerate the species has resulted in the slow conversion of red oak forest to other types.” Most forest research was aimed at jack pine, black spruce and other boreal forest species that have comparatively higher commercial and ecological importance to the province. “We haven’t invested as much time and money learning about it.”

Sylvia Greifenhagen, also with OFRI, provided some oak facts. Oak presently represents 0.9% of our growing stock. Forests that contain oak cover 1,241.8 thousand hectares in Ontario.

Red oak forests have ecological value to Ontario. Acorns feed deer, mice, squirrels, turkey, blue jays and bear, naming just a few of oak’s direct dependents. As a timber product, it is desirable and many local economies depend on it.

Investigating Oak Regeneration
Most oak research in North America is from the US. This can’t be related directly to Ontario but it’s a starting point to discover why oak is not regenerating naturally.

Durland Shumway, in his paper “The 400-year history of fire and oak recruitment,” found there were 42 fires (in his study area) from 1615 to 1958 with sources of fire being lightening and Native American and post European settlement practices. The fire stats break down to nine in the 17th century, 13 in the 18th century, 12 in the 19th century and 8 in the 20th century with none since 1930. He also found that at Crawford Lake, Ontario, beech and maple forests converted to pine/oak “coincident” with Iroquois cultivation and burning.

For purists, fire started by humans whether Iroquois, Huron or European is just not, well “pure.” Dan Dey, in an old OFRI news release, said, “It is not enough to just go in and burn.” He continued, “Fire incidence has changed over time and so has the forest in response to those burning cycles.”

Back in the US, Buckly in “Regeneration of northern red oak: Positive and negative effects of competitor removal” said, “The fossil pollen record in the northern lake states indicates long-term co-occurrence of oak and pine.” He says oak and pine, in that region, fluctuated in dominance for 10,000 years replacing each other cyclically.

We don’t have 10,000 years of data for Ontario. We can only guess that oak was a larger percentage of the forest for a long time. We do know that even without human intervention, lightening strikes and fire affected our forests. We also know that since 1930, fire was suppressed in southern and central Ontario and during that same period oak has declined. Most of the oaks we are enjoying presently for shade and harvest germinated pre-1930.

Planting Oak for the Future
Leaving the purists with their natural wooded areas and parks, Ontario’s forestry industry needs oak. In the 2006 Forest Resources of Ontario report on the OFRI website (Chapter 5, page 100), it states that between 2001 and 2006, oak stands with 61 to 100% oak fell from 52.7 to 37.3 thousands of ha. Stands with 31 to 60% of oak also dropped. Only stands with less then 30% oak increased. (This does not include the far north or agricultural areas.)

We have to wait for the best practice guidelines to be published, but Andree Morneault (MNR) provided a few “tid-bits” of what we can expect.

They studied oak regeneration in four harvest settings including shelter wood at two light intensities of 50 and 70% and selection at two spacing distances of 24 and 36 m. They also tended the forests with three different methods including brush saw, herbicides and fire.

The brush saw plot was labour intensive. The competing vegetation grew back as tall as the oaks by the end of the treatment summer.

Oak is susceptible to herbicides so the trees were protected with ten inch stove pipes. This treatment set the vegetation back for longer than the brush saw and allowed small amounts of vegetation around each sapling to provide some protection from deer grazing.

Prescribed burns were done in research areas that measured about half an acre. “Three year-old saplings tolerate fire well. They have a good root system and buds (average five) at the base in the mineral soil. A slow moving low intensity fire every five years is a good interval to control maple and ironwood. Don’t clean up too much so you leave something else for the deer to eat.”

Bill Parker added, “Time prescribed burns to coincide with years when a lot of acorns are produced.”

In the 50% crown closure areas, everything happens fast. The overstory is removed after ten years but monitoring for competition control is annual. In the 70% crown closure areas, everything is a little slower and there is a little more leeway for errors and more time to make decisions. However, the overstory needs to be thinned much sooner, usually after five years.

The researchers working with Morneault are all senior forest managers with oak sites under study since 1985. “We’ve come a long way in 25 years,” she says, “but there is always more to learn. In North Bay, we had a windstorm in 2006. A lot of the damaged urban Manitoba maples were replaced with oak. Oak just doesn’t drop its branches. It’s a long lived, tough tree, does well in full sun and it is improving the value of the urban forest. It just doesn’t like soil compaction.”

Parker says that a lot of the knowledge we have about oak is locked in a few forester’s brains – many of whom are approaching retirement. We need to reap the benefits of these guys’s legacies before it’s too late.

SIDEBAR 1: OAK WILT. IT'S NOT HERE – YET...

Oak wilt has not been detected in Ontario, according to both CFIA and MNR spokespeople. Surveys were done seven years ago. Since then, both provincial and federal forest health technicians and officers have watched for it.

Ceratocystis fagacearum is the fungi with the potential to kill a red oak in one year. White oaks are killed at a slower rate. It can be spread by Nitidulid or a bark beetle and through interconnected roots. But the most likely mode of transmission is firewood. It is in the same genus as Dutch elm disease. Presently there is no cure and prevention is the best approach.

Jozef Ric, Forest Health Care Inspector with the City of Toronto, says that at this time, they are not altering their planting program to defend against oak wilt as the program is already restricted for concerns like Asian long-horned beetle, emerald ash borer, and Dutch elm disease. The city does have a fact sheet on the www.toronto.ca website under forest health and they are actively educating the public to watch for the condition.

Marilyn Taylor, CFIA, said they are doing all that is possible to prevent the spread of oak wilt from the Michigan and other US states and running campaigns about disease spread and firewood to get the word out.

“Is it enough,” I asked?

I received no answer.

SIDEBAR 2: SUDDEN OAK DEATH. BUFFERED BY THE COLD?

Sudden Oak Death (SOD) has killed over one million oaks and tanoaks in the US. In Canada the effect has been less dramatic – possibly due in part to that wonderful thing we call winter.

Shane Sela, CFIA, says, “A risk assessment completed by the CFIA indicates that the pest is unlikely to survive in Canadian forests, given that the disease appears to only occur in a very narrow climatic preference (the fog-belt of southern California). It also requires specific hosts such as bay laurel or tan oak to spread.”

Interestingly, US studies show that essential wood oils (those lovely smelling substances extracted from trees and used for cooking, candles and medicinal purposes) inhibit zoospore germination and hyphal growth of Phytophthora ramorum – i.e., they slow or stop the spread of SOD.

Western red cedar and incense cedar extracts damaged twice as many spores as extracts taken from Alaskan yellow cedar, western juniper and Port Orford cedar. Douglas fir and redwood extracts showed little to no effect against the spores.

The USDA suggests spreading wood chips, shavings, sawdust or the extracts in high traffic areas to reduce spore movement.

— Pat Kerr

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