Saturday, May 22, 2010

Spring Wildflowers

Here's a few pictures of wildflowers I have seen in the Don Valley this spring. All of the pictures except the Spring Beauties are from the Lower Don and neighbouring tributary ravines.

Canada Mayflower

Wild Sarsaparilla

Virginia Waterleaf

May Apple


Spring Beauties

Trout Lily

Wild Geranium

White and Purple Violet

False Solomon's Seal

Wild Coffee

Thursday, May 20, 2010

Pottery Road Work Postponed Til 2011

In Bring Back the Don's Spring 2010 newsletter, it was reported that Pottery Road would be closed for construction for 6 months starting in June. I've just learned that this work is to be postponed until 2011. The reasons are due to other road work priorities and staffing issues in the engineering planner's office.

Wednesday, May 19, 2010

Mute Swan Nesting on Don Debris

Lakeshore Blvd. East bridge at mouth of Don

I was passing by the mouth of the Don recently and noticed something odd underneath the Lakeshore Blvd. East bridge. Next to one of the bridge abutments is a pile of sticks and debris that often collects beside the river. This stuff is eventually washed away during a heavy storm. However, this pile of sticks seems to have attracted the attention of a pair of Mute Swans and they have taken it over as their spring nesting site.

Nesting site

The Mute Swan is an introduced species in North America native to Europe and parts of Asia. There is some evidence to suggest that the species is becoming invasive in the Great Lakes region and control measures may need to be implemented. There is at least one group that claims the species is native to North America and needs to be protected but the U.S government disputes this assertion. So far these birds are not a big problem in the Don. Native species such as the Trumpeter Swan are also rare but this is due to lack of habitat.

For this pair of birds things appear to be OK for now but it could be bad news if there is heavy downpour in the next few weeks. If you're rooting for these swans, then cross your fingers and hope for the rest of May to be dry.

Mother appears to be doing fine. Swan lovers will wish for a dry spring

Saturday, May 15, 2010

Invasive Species of the Don: Garlic Mustard

Garlic Mustard (Alliaria petiolata) showing flowers, seeds and leaves

A few years ago I wrote a blog post called the Top 5 Threats to the Don. At the time I thought that each of these would make a good post but I soon realized that they all were much larger and complex than could be fit into a single post. The second item, non-native invasive species is one of these complex items. I thought that this year I would try to tackle this item as a photo essay about individual species. This is the first of these posts.

Garlic Mustard (Alliaria petiolata) is a non-native invasive plant species that is one of the problem species in the Don Valley. Actually it is causing problems throughout southern Ontario but it grows especially well in disturbed conditions of which the Don has more than enough such places.

Introduced from Europe as an edible herb, it has escaped cultivation and has invaded our natural areas. It grows in a variety of light conditions from full sun to shady forest understory. It is found in all types of soil except for very wet conditions. Garlic mustard is a biennial meaning that it lives for two years. In the first year a low basal rosette of leaves grows and it remains green throughout the fall and winter. In the following spring the plant grows a stem and flowers. Plants can range from a few centimetres to about a metre in height. It produces small four petaled white flowers which is a characteristic of the mustard family. Soon after flowering, seed pods emerge which first appears as thin green sticks standing upright around the flower stalks. Each seed pod can contain up to 20 seeds. A large plant can produce hundreds of seeds.

In addition to producing plentiful seed, the seeds that it does produce can remain viable for up to 11 years in the soil so that makes it very hard to get rid of it. Animals like deer who naturally feed on forest plants are not used to Garlic Mustard and avoid it, eating other native plants. This creates a positive feedback loop which allows Garlic Mustard to spread even faster.

First year Garlic Mustard rosette in early spring

If all this isn't bad enough, it turns out that garlic mustard is allelopathic. In other words, the roots produce a toxin which kills soil fungi. Many native plants have formed symbiotic relationships with a group of fungi called mycorrhizae. These organisms wrap tiny tethers called hyphae around the roots of plants. The hyphae gather water and nutrients from the soil and transfer it to the plant. In exchange the plant trades sugars and starches gained through photosynthesis for water and nutrients that the fungi collects. When these soil fungi are removed, this inhibits the growth of native plants in our ecosystem.

Another problem that has been noticed is that in areas of abundant garlic mustard tree seedlings are not as successful as they should be. Garlic mustard seems to inhibit their growth. This combination of hardiness, plentiful seed production, allelopathy, and ecosystem effects means that Garlic Mustard can soon overwhelm a natural site and become the dominant species. In some cases the only species growing is Garlic Mustard.

Forest understory in the lower Don Valley. 99% of the plants on the ground are Garlic Mustard

Garlic Mustard is not just limited to parks and ravines. It is also making its way into gardens. What can be done about this nasty invader? Hand pulling is the recommended method. To remove it grasp it tightly as close to the ground as possible and gently pull. Try to get as much of the root as possible because some root fragments have been known to resprout. The roots are not that deep and should be easy to pull out intact.

If you want to help protect our natural areas from this plant and others like it you can join one of the the city's Community Stewardship teams. This volunteer program runs during the spring and summer and helps to protect some of the Don's more important natural areas. Teams meet once per week and remove Garlic Mustard and other non-native invaders.

Roots of a typical plant

Discard the plant into the regular garbage or the kitchen green bin. Don't put it into your garden composter because it will only become contaminated with Garlic Mustard seeds. For large amounts you can put them into a yard waste bag for city pickup.

Saturday, May 08, 2010

Don Council Tour

Kortright Centre

A couple of weeks ago I went on a bus tour of around the Don watershed. Actually one location was in the Humber watershed at the Kortright Centre where we stopped for lunch. The tour was prepared on behalf of the Don Watershed Regeneration Council which has been recently reconstituted with a new group of members. The current council consists of a mix of new and returning members and a mix of young and old, male and female. The council which was created by the Toronto Region Conservation Authority is made up of representatives of non-profit groups interested in Don Watershed restoration efforts and private citizens who are interested in the environment. I sit on the council as a representative of Friends of the Don East.

The current mandate of the Don Council is to press forward with the implementation of the Don Watershed Plan created by the TRCA.

The tour started at Yonge and York Mills and looked at the West Don River where it runs through a flood control channel. There is a project that will clean out part of the river basin that has become clogged with debris. The project is somewhat controversial because the debris and silt have been there for so long that substantial trees have since grown there.

G. Ross Lord reservoir

The second stop was the G. Ross Lord Dam up by Dufferin and Finch. The dam which was built in the 1970s by the TRCA is used for flood control on the west Don. The reservoir is big enough to hold 5 million cubic metres of water. This may sound like a lot but it filled up during the August 2005 storm. This was the storm that washed out Finch Avenue where it crosses Black Creek.

For lunch we stopped at the Kortright Centre where we were given a tour of some sustainable living features that the TRCA is showcasing for local developers. All of the features use current technologies to help reduce the footprint buildings have in the watershed.

Richmond Hill stormwater pond

The 4th stop was a stormwater pond in Richmond Hill and the 5th stop was at the East Don Parklands wetland which I previously wrote about. The last stop was at Earl Bales Park. This featured a tour of a new stormwater pond due to be built in the southeast corner of the park.

Council members mucking about in East Don Parklands

Saturday, May 01, 2010

Earl Bales Stormwater Pond

Site of stormwater pond (click to enlarge)

Schematic of proposed pond in the valley. The light green area at the top right is the golf course.

A couple of schematic drawings of the pond. A path on a causeway will lead to a lookout and interpretive area.

This summer a major construction project will take place on the West Don at the southeast corner of Earl Bales Park. This project which is the culmination of several years of planning will create a stormwater management pond that will capture storm water before it enters the Don River. The pond location is at the base of two creeks, Earl Bales Creek and Dehavilland Creek. Both creeks used to run west towards the Downsview Park area but are now mostly buried in storm sewers. The remnants of their ravines are now confined to the park east of Bathurst Ave. Both of these ravines are severely degraded due to flash flooding from storm water.

Outfall from former DeHavilland Creek. This will be diverted into the new pond

The purpose of the pond is to capture the stormwater before it enters the river. Stormwater and its resultant pollution is the single most important environmental problem affecting the Don River today. When rain falls on a watershed, the water is either absorbed by trees and other vegetation or percolates into the ground. The water eventually enters the river at a steady rate. However, in an urban watershed like the Don, ground cover is dominated by roads and buildings. Water falling on these areas is quickly diverted into storm sewers where it floods into the river. These flash flood events tend to scour out the creeks and rivers. The water picks up dirt and mud and other things. All the suspended material including whatever pollutants from the roads (road salt, oil, grease, etc.) is washed into the river which severely degrades available habitat for fish and other water dwelling organisms. The Don River used to be a healthy river teeming with fish but not any longer. The "Muddy Don" got its nickname because we made it that way.

This stormwater pond is just one small aspect of the slow process of river restoration. Its main purpose will be to stop the stormwater from quickly entering the river. The water will be stored here until the suspended material has had a chance to settle to the bottom of the pond. It is estimated that 20% of the 35,000 cubic metres of silt annually dredged from the mouth of the Don River comes from the Earl Bales park area.

The pond site looking southwest toward the foot of Westgate Blvd.

Looking northeast

The pond will also act as a reservoir for two nearby water uses. The Don Valley Golf Course currently draws water from the river for its grass watering needs. The Earl Bales Ski Hill also does the same for snow making during the winter. After the pond is built the water will be taken from the pond instead.

The pond will provide limited habitat for some wildlife. However it will not be a fully functioning wetland since it will need to be periodically dredged which will cause major disturbances in the pond. Yet overall, the effect will be an improvement in the overall health of the river and the Don Valley. I hope to visit the site a couple of times this year to document progress on this project.

Notice of construction at entrance to the valley at Westgate Blvd.