ECOSYSTEM RESTORATION and INTRODUCED SPECIES:

Ecosystem preservation and restoration are the essential ingredients of a rich biodiversity in our community. Last issue, Lois Gardner introduced the values of the special ecosystems. If we look at the strategies that we might use to promote biodiversity in the community, we can end up with a tool box ideas and actions. Recently we saw one of the first examples in Metchosin of granting a covenant under the new provincial legislation. A good look at what is involved with that "tool" will form the basis of a future article. Other tools are at our disposal, but we must take an active role in making them work.

One such tool to enhance Biodiversity that we can all get involved with is the control and eradication of a select group of introduced species in Metchosin. It does little good to set aside parks or green spaces if the very species they are intended to protect are soon overwhelmed and displaced by more aggressive competitors which humans by intent or accident have unleashed. There was a time when we could just stop pulling the weeds and in a few years, all would revert to biodiversity heaven. We are beyond that phase now so it requires some more purposeful intervention by us to help restore natural systems to their former healthy complexity.

Often going under the name of alien species, exotic or opportunistic species, we can focus on those few species with which Metchosin is particularly cursed that I will refer to as "Introduced Species". (Unfortunately we are all in that category, so we have to be pragmatic enough to accept that our efforts will not be one hundred percent successful.)

When we speak of introduced species, we are not referring to the Kiwi fruit, and garden tomatoes or most of the flowers in our gardens. The ones we are mainly concerned with could best be put in the category well understood by Metchosinites "if the sheep won't eat them, beware!- you're in for trouble."

A story of my own naiveté will demonstrate. When we moved to our farm in Metchosin 13 years ago, I was impressed with that shiny-leafed plant which looked much like a dwarf Rhododendron without the showy flowers. It seems that some innocent soul after Sir James Douglas and before me had decided they were homesick for a bit of Europe, and thought that this pleasant little shade loving plant would be a perfect addition to our little community with those meadows of tedious blue camus! The plant was perfect, it stayed a shiny green all year, could grow well under the shade of the conifers, was deer resistant, could be controlled in the garden by pulling in the wet season, and withstood the drought of August without a bucket of water. Furthermore, if the sheep got out it would survive when the sweet peas didn't. . This perfect "survivor" it turns out is the garden Daphne or Daphne laureola.

Last year in the summer, my son and I thought we could make an impact on this intruder down in our forest with a brush cutter. After twenty minutes, we found that we had a stinging sensation in our throats, so we gave up on that method. It got its revenge by discharging a chemical into the air as the brush cutter ripped through, probably the same one that the sheep find so distasteful. So here we have a plant that relies on chemicals as a defense to give it the edge on other species.

Now to get to the real reason that species like this are a serious threat. By changing the light availability and probably the soil chemistry and pH , Daphne prevents normal succession in a forest. That's the process of change from one community of plants and animals to another as an ecosystem is going through the stages of natural regeneration. The waxy leaves of Daphne form such a solid canopy that tree seedlings, ferns and all those species that should normally grow are excluded. Typically the ground underneath is bare, not a great condition to prevent soil erosion either. This spring I observed that on the advancing front of these bushes, the erythronium lilies are slowly being extinguished.

Of course this just demonstrates some of the many techniques used by typical introduced species. These organisms were successful in colonizing an ecosystem because they had special adaptations that gave them control of their environment (sound familiar?) Some, most commonly plants, use thorns as a protection, especially if they originated in an area that was arid. Typically you can see the result today in Greece and countries of the middle East, where humans have grazed sheep, goats, camels and cattle for millennia. Natural Selection has insured that only those species capable of withstanding the grazing animals of humans will be successful.

We have just come through a most colorful month in Metchosin with all that yellow on the roadsides with it even creeping into the forest. Congratulations, each plant that was two to three years old has just produced 2000 to 3500 seed pods per bush and each pod has up to 9 seeds, quietly maturing but soon to explode and scatter. Scotch broom, introduced in Sooke in the 1850's, indeed had a good season, and with those seeds able to remain dormant up to 30 years, we are guaranteed to have degraded natural landscapes for some time!

Gorse, with an early display of cocoa-butter smelling yellow flowers in March is now even recognized by the forest service as a major threat because of it's explosive flammability. In 1994, the ministry of forests sent out a letter to council requesting information on the spread of Gorse. Today Metchosin harbors whole fields of this plant. Both broom and gorse have parasitic insects that are possible as biological control agents, but research on their use in BC has been slow. Meanwhile if we all did our bit to eradicate them, we would give other native species a chance. Recent evidence indicates that Broom and Gorse exude toxic alkaloids from their leaves and roots, thereby changing the chemical make-up of the soil, often rendering it unfit for our sensitive native plant species.

The trouble is that rarely in history have humans been able to understand the value of biodiversity, and fully functioning natural ecosystems, let alone what inhibits our efforts to enhance and protect biodiversity. Often we have had to look at a species from the utilitarian point of view, and the worn out excuse of "it may provide the key to a cure for cancer," in order to justify the right of the species to exist.

Lest you think that plants have the monopoly, we should review the case of the Gray Squirrel. The native red squirrel fit in very nicely in the forested Garry Oak ecosystem. It was only in recent years that the gray squirrel was introduced to Southern Vancouver Island and should rather be considered as bushy tailed rats. If one looks only at this one species, it appears to be rather charming, but when the whole system is considered its a different story. The gray squirrel is a voracious feeder on nesting birds, both eggs and young birds, in addition it does a very efficient job of consuming all the acorns of the Garry Oak because it often stores them in tree cavities, and it forages on the ground for a complete take. The native red squirrel, now pushed aside by competition from the gray was perhaps more forgetful and liked burying the acorns, thus assuring certain regeneration of oaks. Further, it left a few acorns for other consumers, such as the now diminishing band-tailed pigeons. In the autumn, these birds rely on the rich source of oil from the acorns to get them across the Strait of Juan de Fuca and down the coast in their migration. It was over five years ago that I last observed a flock of 75 of these birds swoop through our Oak grove and stock up on migratory supplies. So here is a suggestion that the thoughtless introduction of one species has led to the decline and perhaps eventual extinction of at least three others.

What about the European Starling problem in Metchosin?. The increase in the last few years of this species has amounted to a population explosion. This is not happening without a predictable displacement of a number of native birds species, especially the tree cavity dwellers, and soon we will wonder why they too have disappeared. Again, natural predators are few, we even encourage starlings by providing suitable shelter, and a comfortable life style in Metchosin!

Look in the sheep- grazed fields of Metchosin where orchard grass is the main grass left standing after the sheep have been rotated through. All of these species make adequate hay but because of their lack of palatability, they are not consumed as readily by the sheep, consequently their seeds remain to ripen and replace the more palatable species. If these species had spread naturally, without human intervention, they would have had time to bring with them all the parasites and predators that kept them in check in their native countries. If you are trying to reestablish Garry Oak meadows, you probably will first have to deal with the problem of introduced grasses.

So where do we start?

The alternative if we are unwilling to act, is impoverished ecosystems with low biodiversity, extinguished species and with undesirable introduced species predominating.

PARTS OF THE ABOVE ARTICLE by Garry Fletcher were published originally in the Metchosin Muse:

You are encouraged to contribute photographs of methods and ideas for ecosystem restoration Metchosin. Any methods you have found useful for control of introduced species can be added to the site.

GIANT HOGWEED


TANSY RAGWORT

A few days after the above article was published, I received an e-mail from Colin Frost of East Sooke. He told me of the introduced weed Tansy Ragwort which was starting to invade roadsides and pastures in that area of Southern Vancouver Island. He also provided me with a background sheet on the species.

It starts as a rosette of leaves and then sends up a spike up to one meter in height the following season. It was apparently introduced to Oregon as a source of yellow dye.

It is toxic to cattle and horses when it is consumed in hay.

The LICORICE SLUG

Also I have recently heard of an introduced slug in this area called the licorice slug. This summer we had a particularly bad invasion of these slugs in the Metchosin area, but little information is available on them so far. This picture shows a 3-part photo of the slugs possibly mating and laying eggs.