Wednesday, April 29, 2009

The Great Mulching of 2004

Worm vs carabid larva - a nose-to-the-ground moment.

If any of you ever decide to turn your lot into a bug garden, or plan any major renovation of your garden, then I highly recommend that you first have a plan that maps out what the garden will look like when it is finished and the new plants have grown to their full size. We at the Home Bug Garden Wannabe were fortunate to have a friend, Adrian Thysse, with the expertise and interest in ‘naturalistic gardening’. You can learn a bit about Adrian’s naturalistic gardening and enjoy many a striking picture at Gardening Zone 3b.

The first choice we had to make was how much lawn did we want to keep? I think I’ve already expressed myself about lawnmowers, but to put a more positive spin on it, Dennis vanEngelsdorp has a great slogan “Make Meadows, Not Lawns” (hat-tip to Bug Girl). I didn’t want any lawn, but my wife wanted a bit of green near the pond-to-be. Also, on reflection, all the neighbours have lawns and offending them wasn’t on the agenda, so I decided to keep the first two metres of the front lawn intact (the city owns that land anyway). That way people walking by could have their grass fix and a chance to admire the contrast with the rest of the garden. The rest all had to go.

The mulching begins.

Adrian suggested newspaper, mulch, and patience, rather than removing the turf or glyphosphate. The technique involves laying down a layer of a half dozen sheets of newspaper directly on the lawn and covering it with about a decimetre (4”) of mulch. This blocks off all light and the lawn gradually dies and turns to compost, resulting in a nice bed to plant into. Newspaper may work okay in a dry year, but 2004 was very wet and the weeds and grass started popping through. I then switched to cardboard – that works better, but crabgrass is an amazing plant that can even puncture its way through landscape cloth (don’t use the latter if you are planting perennials into it – the roots tend to run along the underside of the cloth and will be badly damaged if you need to remove the cloth or move the plant). For the really tough spots, I ended up using 1/8 inch plywood – nothing gets through that. Another advantage of this technique is that you spend a lot of time on your hands and knees with your nose in the ground and get to see lots of neat insects.

And so it began, mulching and planting through with things we thought pollinators and birds would like. Yes, the original Home Bug Garden idea hadn’t really developed past the birds and bees stage, but it was a start.

Andrena bee departing a globeflower

Thursday, April 23, 2009

Crabgrass, Dandelions, and a Dying Birch II

When last we visited the early evolutionary stage of the Home Bug Garden, I ended with a serious aesthetic problem in the front yard (a birch dying from drought and beetles) and a bit of a moral dilemma (I’m not against pesticides properly used, but poison in my own yard? and pay for it?). Moreover, the birch was surrounded by alien invasive plants – plants officially listed as ‘nuisance weeds’ in Alberta: quackgrass (aka crabgrass) Agropyron repens and dandelion, listed as Taraxicum officinale, but actually a complex of mostly asexual ‘species’. Although a weed, I’ve always found dandelions fascinating – edible leaves, flowers with which you can make wine, and a nagging question - why does an apomictic plant place such a large investment in flowers and nectar that gain it no obvious benefit at all?

‘Nuisance’ is the lowest rank under the Weed Control Act, ‘Noxious’ is worse, and ‘Restricted’ a real problem. However, it didn’t take much poking around to find that our new yard was infested with quite a few other nuisance weeds that we were supposed to ‘prevent the spread of’ (e.g. Creeping bellflower, Wild buckwheat, Common chickweed, Rough cinquefoil, Hemp nettle, Annual sow thistle, Shepherd's-purse, and probably several other weedy mustards that I was too lazy to key out) and two ‘noxious’ weeds that we were obligated to ‘control’: lots of Canada Thistle (Cirsium arvense) and one Oxeye daisy (Chrysanthemum leucanthemum). To add to the complexity of the problem, these weeds were providing the only real sources of nectar and pollen in our yard.

To top this off, I hate mowing the lawn, hate the sound of lawn mowers, and generally think weekends should be for relaxing in the garden with a couple of bottles of wine, a good book, and some good food. My wife found a non-solution to the second complaint – she bought me a push mower - but that did nothing to quiet the neighbours, and in general I would have to say that push mowing, while inducing a certain sense of moral superiority, is not conducive to relaxing weekends. Push mowing weeds interspersed with spruce cones and birch branches is especially lacking in satisfaction.

Thus came the idea of a ‘home bug garden’ – why not get rid of all these weeds and plant lots of good plants, especially ‘natives’, and make our home a nice place for people and bugs (and other animals)? Why not do nothing about the birch (only the top 2m were dead and at least that gave our garden one species of beetle), but almost completely replace the grass and weeds with a diversity of herbaceous perennials, shrubs, trees, and potager beds of vegetables, herbs, and annual flowers? I’ll deal with the extermination of the enemy weeds, the rediversification of the flora, and the exploding diversity of arthropods and lesser animals in later posts – it took a long time. The birch also took a long time, but is simpler to explain.

If you have a tree infested with a destructive beetle pest such as the bronze birch borer, you may have a moral (and possibly a lawful) obligation to your neighbours. As the new generations of beetles emerge, they won’t just eat more of your tree, but disperse to your neighbours’ yards to continue the outbreak. Chemical control of insects under bark is difficult, expensive, and limited by legislation. When thousands of trees are already dead and dying around you, and producing large crops of beetles, then you have no hope of protecting your tree. Probably the most logical and practical approach would be to drop the tree, bark it, and burn it. We didn’t adopt this simple solution, nor did most people in our neighbourhood: the dead birch are gradually being removed, but it has taken years. We, instead, tried to keep the tree healthy and limit the infestation by aggressive watering – made easier than expected by the end of the drought.

This ‘water and pray’ approach was completely ineffectual and ultimately more costly than the logical solution, but did have the advantage of keeping the birch limping along until at least last Fall (only the aspen have yet to burst bud this year, so no prediction). Birch are pretty trees, and the birds certainly like foraging in ours each spring, fall, and winter. In 2008 we installed a bird house on one of the dead boles, and a house wren (Troglodytes aedon) soon chased off the rather bird-brained house sparrows (Passer domesticus) that spent much of that Spring trying to force themselves into the too small hole. But each year the beetles spread further and further down the bole.

During a storm in the winter of 2004-5, the top 2m of one bole came crashing down. Fortunately, no person or plant was hurt, but it was obvious we had to do something, so we forked out $200 to have the beetle infested tops of the tree cut out – and baked the logs in the sun to kill the beetle larvae. The next year another few metres of tree were dead, and so on. The birch has tried to come back and sprouted from the base, but all but the last metre and a half of the bole is dead. This Spring we spent another $200 to prune it to about 4m height, just above the level of the bird house.

So did we obtain any benefits from ‘water and pray’? Well, yes, I think it has been just about worth it. Birch branches make excellent poles in the garden and segments of trunk make very attractive stands for bird-feeders and nice backdrops for informal beds. A dead tree may look unsightly, but when every other yard in the neighbourhood has a dead birch, there doesn’t seem to be much social pressure to remove it, and a dead tree is heaven to a bird or a bug. Did we save any money? Well, no – we could have had the tree removed for little more than the initial topping and the extra water we put on cost dearly. But how do you estimate the benefit of five years of migrating warblers foraging in the tree, of wrens, chickadees, and nuthatches checking out the bird box, or of strange spittlebugs drowning even stranger wasps? In the Home Bug Garden, the last trumps all.

Saturday, April 18, 2009

The First Flies of Spring

Easter weekend was the first real sign of Spring 2009 in Edmonton – warm enough for a few insects that had overwintered as adults (or pupae ready to emerge) to take to the wing. Although the eye is naturally drawn to the larger and more brightly coloured individuals, e.g. the Milbert’s Tortoiseshell butterflies (Aglais milberti) that have consistently shown up in early mid-April for the last three years or the ladybird beetles that overwinter in the mulch and leaf litter, a host of smaller and less obvious animals come out to enjoy the early spring sun. Prominent among these are the flies.

One of the most diverse orders of insects, but one that is rarely celebrated, is the Diptera or two-winged flies. If you want to know the identity of a fly, then it helps to have a friend that knows their flies (we are lucky to have several such friends). It also helps to have a pinned (but not wriggling) specimen, because the sad fact is that many insects cannot be identified except by close microscopic examination. However, if you are trying to grow a Home Bug Garden, then it seems perverse to kill the insects that live there (mosquitoes, perhaps the least loved of all Diptera, excepted).

So, except when some arthropod pays the ultimate price, identifications on this blog will be tentative ones based on photographs or observations. Take all such names with a grain of salt and remember that the higher the taxonomic level, the more likely the identification is to be correct. Thus, family names will usually be correct, genera less so, and species least of all.

As I was saying, the sunny Easter weekend lured out a few flies of more than passing interest and we were able to add two families to our Home Bug Garden records: a member of the family Lauxaniidae (possibly a species of Sapromyza) and two species of shore flies (Ephydridae): one a member of the genus Paydra (sometimes known as fat-faced flies) and the other possibly of Ephydra (or a related genus). All three of these flies are tiny and inoffensive. The larvae (i.e. maggots) of the lauxaniid may mine leaves, but unlike the pesky agromyzids that make a mess of my columbine, beet, and pea leaves, lauxaniids mine dead, decaying leaves (see p. 416 in Marshall 2006). The larvae of the shore flies feed on microbes in wet spots – probably the decaying vegetation in our pond or bog. So these flies are actually helping the garden by releasing nutrients otherwise tied up in decaying vegetation and microbial biomass.

Larger and more problematic are the blowflies. Probably everyone has seen members of the Calliphoridae (blowflies, bottle flies, screwworms), whether they realize it or not. The bodies of these flies often have a green, blue, or coppery metallic sheen and they are very common around humans because the maggots generally feed on flesh, often carrion (including the dead meat we like to throw on the barbecue), but sometimes in living flesh as is the case with the screwworm. Actually, like the shore flies, the maggots of many calliphorids are more interested in the microbes than the meat, which is the reason they are useful for cleansing festering wounds in Maggot Debridement Therapy. This is true of the Northern Blowfly (Protophormia terraenovae), a carrion fly that is also useful to CSI types that need to estimate the time of death.

I suspect one reason that carrion flies are common in the early spring in northern climes is that when the snow melts, the animals that failed to survive the winter become available for consumption. Some spring ephemeral plants take advantage of the flies that are attracted to carrion for pollination. For example, the red flowers and fetid odour of Stinking Benjamin (Trillium erectum) appear to mimic red, rotting meat and are pollinated by a variety of flies that are attracted to carrion.

If you’d like to learn more about Diptera, or indeed any other group of insects in North America east of the Rocky Mountains, then I highly recommend Steve Marshall’s magnificent Insects. Their Natural History and Diversity.

Friday, April 17, 2009

Crabgrass, Dandelions, and a Dying Birch I

Front yards in our Edmonton neighbourhood are fairly uniform – grass maintained at various degrees of perfection, a spruce or two, and perhaps a white birch, mountain ash, or low growing conifer. Plantings of annuals and herbaceous perennials tend to be near the foundation or in a narrow bed along the front walkway, so that whatever isn’t shaded out by the spruce is covered with grass. Weekend mornings groan with the sound of lawnmowers. In July 2002, we managed to garner one such yard with a mature specimen of cutleaf weeping birch (Betula pendula) in the midst of a ratty expanse of crabgrass and dandelions and flanked by towering spruce.

Weeping Birch are beautiful trees, especially in the winter, but they need a lot of water. For the five years or so previous to our arrival, Edmonton had experienced a prolonged drought. When water-stressed, birch are susceptible to attack by the infamous bronze birch borer (Agrilus anxius). The larvae of this small (~10 mm) blackish beetle bore through the cambium of the tree and kill it from the top down. The bronze birch borer was happily munching away on North American birch when European colonists arrived, but the weeping birch was introduced from Europe and appears to be especially susceptible to its attack. The top metre or so of each stem of the multi-stemmed birch that we acquired was already dead and infested with beetles eating their way towards the ground. Thus, we were immediately confronted with a serious aesthetic problem in the front yard and a bit of a moral dilemma.

In the posts that follow, I will be meandering between describing the evolution of the Home Bug Garden and more spontaneous posts about what is happening at the moment. Every now and then I will have a rant about something I think is important - after all, that is really what blogs are about.

Monday, April 13, 2009

The '200 year flood and hail storms' July 2004

On Canada Day in 2004 we had a garden party to celebrate our newly mulched and planted Home Bug Garden. The next day, a massive thunderstorm dumped as much as 60 mm of rain in a few hours . Our rain gauge kept overflowing, so I'm not sure what the Bug Garden got, but much of the mulch floated down the street and the basement flooded. Nine days later (11 July 2004) a second thunderstorm dropped up to 150 mm (~ 6") of rain and hail, flooded the front street to about 1 metre, covered the ground in more than a decimetre (4") of hail, shredded most of the leaves in the garden, and again flooded the basement. Pictured above left is the front street and above right a low spot in the Whitemud freeway.

A 'native' bumblebee interacting with an 'exotic' plant.

The goals of the Home Bug Garden are (1) to have fun gardening and (2) to create an urban oasis for wildlife. Although this might seem a simple set of goals, #2 raises a number of immediate questions, e.g. 'what is wildlife?' and 'what should I be planting to encourage them?'.

The Coming-Out of the Home Bug Gardener

This is the inaugural posting for the Home Bug Gardener. The theme of this blog will be how a small plot of urban land can be changed from a sterile and mindless conformity to an oasis of biological diversity. Well, perhaps not everyone’s cup of biological diversity, but the essence of biodiversity: lots of species living together.

This project started about 6 years ago in Edmonton, Alberta, Canada. Edmonton is an urban island of relative warmth (Zone 3b in a good winter – i.e. rarely going below -40C/F) in what used to be Zone 3a Aspen Parkland, a transition zone between the prairie and the boreal forest. The area in which we live used to be a slough (i.e. a wetland, not quite a lake and not quite a marsh), but it was filled in after World War II and covered with black clay and small houses for returning soldiers (our house was built in 1951). Eventually, the streets were planted with boulevard trees, primarily green ash and American elm. Weeping birch and other drought-intolerant Betula were soon adopted as specimen trees. Apple-crabs, crabapples, and a variety of mountain ash (rowan) also made their appearance. In the early 1960’s, the Girl Scouts arrived with a variety of conifers (white spruce, Colorado blue spruce, and a few black spruce) to celebrate Arbor Day. As a result, even with a southern exposure, sunlight can be limited.

That is the background. Time, energy, and enthusiasm permitting, the story will follow.

Suggested Reading:

Owen, Jennifer. 1991/2005. The Ecology of a Garden: The First Fifteen Years
Cambridge University Press
ISBN-10: 0521018412
ISBN-13: 978-0521018418

Tallamy, Douglas W. 2008/2009. Bringing Nature Home: How You Can Sustain Wildlife with Native Plants, Updated and Expanded
Timber Press
ISBN-10: 0881929921
ISBN-13: 978-0881929928

Relevant web visits:

Biodiversity in Urban Gardens in Sheffield