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Sunday, February 26, 2017

The emperor is partially clothed

As garlic mustard leaves start to show among patches of melting snow, I’m revisiting the issue of nonnative invasive plants. Garlic mustard takes over the North American forest floor by producing chemicals to suppress mycorrhizal fungi other plants’ roots needs. Garlic mustard pulls make plausible community projects, because the plant is small, distinctive, and easy to uproot. 

Garlic mustard in flower

    Before we pour more volunteer power into fighting nonnatives, though, I think we should take a more nuanced look at the ideology behind this effort. 

    Of course, part of the reason that gardeners are concerned about nonnatives is that native animals, including the many insects we need near the base of the food web, haven’t evolved to live off these plants. One of the most eloquent spokesmen for this concern is Doug Tallamy, whose book Bringing Nature Home inspired many gardeners to choose native plants for our backyards. I’m on board with his recommendations, and I’m prioritizing natives when space opens up in my garden.

Native flowers feed native insects

    But it turns out that the science regarding nonnatives is not as simple as “natives good, exotics bad.” Recently I’ve read two fascinating books on this subject, The Rambunctious Garden: Saving Nature in a Post-Wild World, by Emma Marris, and Where Do Camels Belong: Why Invasive Species Aren’t All Bad, by Ken Thompson. Both provide many fascinating examples that illuminate the contradictions inherent in the simplistic strategy of making war on nonnative plants (sort of analogous to the problems with blaming human immigrants for our nation’s problems). 

    Two principles I’ve learned from these authors have changed my perceptions of imported plants and animals. First there’s the issue of baseline. What’s Year One for deciding who’s native and should be protected? In the US, many conservationists would choose 1492, assuming that introduction of new species to North America started with European settlement.

Plant migrations didn't start with the Pilgrims or even Columbus

     That presumes that Native Americans didn’t alter the landscape, which is completely untrue. It also ignores the climate shifts and changes in geography that have occurred over geologic time. Different plants grew in Massachusetts in warmer epochs than when glaciers advanced southward. We humans have a problem with historical perspective.

    Second, when introduced plants take over, it’s usually in response to human-caused changes in habitat. We’re blaming the plants for the results of our own action.

I was surprised to learn that purple loosestrife is not reducing biodiversity in our wetlands

    How ever you come down on this highly emotional issue, there’s little chance of wiping out introduced plant species except in very special circumstances, such as on islands. We might pull all the garlic mustard from a beloved park, but seeds would be left behind in the soil, and plants don’t respect park boundaries. It’s a permanent commitment to moving a mountain with a teaspoon. 

     We’re just starting to understand invasion biology. Before we add more nonnative plants to our enemies list, let’s get more scientific evidence about how plant populations really work and save some energy for combating climate change, the biggest challenge of all for plants in the wild.

Plants can't migrate as fast as the climate is warming

Sunday, February 19, 2017

Mouths to feed

On a cold, snowy winter’s day, it’s lovely to see wild birds in the backyard. Last week I spotted nuthatches and a woodpecker at the suet feeder, chickadees hopping around the big hydrangea vine, and a female cardinal scoping out territory for this spring’s nest. Although my garden doesn’t attract rare, shy birds (or if it does, I don’t know enough to spot them), I like the idea of providing food and habitat on my suburban lot.

Thistle seed attracts small birds, including goldfinches

So it was a jolt to read in Cornell Lab of Ornithology’s magazine that “. . . although feeding birds may not be harmful to the species that use feeders the most, it also isn’t helpful to the species that most need our help.” Emma Grieg, leader of the lab’s Project FeederWatch, goes on rather condescendingly, “But don’t take down your feeders in despair. One of the most important impacts of feeding birds is that it allows people to feel connected to the natural world.”

    Wait a minute—harmful? Research by Grieg and Cornell Lab Citizen Science Director David Bonter assesses the balance between positive impacts of bird feeders—supporting populations of regular feeder guests such as northern cardinals—and negatives, such as “disease transmission, deaths from window strikes (when birds fly away from a feeder and into a house), and increased predation pressures," as when hawks eat bird feeder birds.

It's squirrel-proof, but is this feeder bad for backyard birds?

    I’m one of more than 50 million North Americans who feed backyard birds. I have a tube feeder for mixed seed, a hopper feeder for sunflower seeds, a thistle feeder, and the suet feeder for woodpeckers and nuthatches that like to eat hanging upside down. Last fall I bought ten 20-pound bags of birdseed at Mass Audubon Broadmoor Sanctuary’s Bird Seed Day Fundraiser. 

Blue jays are fun to have around

     I’d never thought there could be anything negative about bird feeders until I read George Adams’ book Gardening for the Birds: How to Create a Bird-Friendly Backyard.

     In addition to the potential harm noted by the Cornell researchers, Adams points out that birds evolved to forage for seeds and insects on their own. If they come to depend on food from our feeders, they could go hungry when we leave town. Also, we may be changing population dynamics, causing booms in feeder-reliant species, including nonnatives such as European sparrows.

Flocks of European sparrows can grab all the available food--Hopkinton News photo

     Is feeding birds just a feel-good activity, another ham-handed human intervention that gets in the way of natural processes instead of helping?  The Cornell article presumes that our goal in feeding birds is to save endangered species. 

     That’s one goal, but I have others. In winter, I’m proud to feed ten native species on Mass Audubon’s list of common backyard birds of the Northeast. I think they deserve to flourish, even if they’re not rare, and I know they’re contributing to the health of my garden ecosystem. 

Downy woodpecker hunting for insects

       To encourage birds to do their part in the garden by eating insects, I’ve stopped putting out seed in summer. I just need to get in the habit of washing those feeders more often.

Feeders need cleaning so they won't transmit diseases between birds

Monday, February 13, 2017

Less lawn in 2017

Although there’s snow outside my windows, plans for the 2017 garden are swirling in my head. One gnawing issue is the lawn around the deck. It mostly doesn’t exist. 

Spring photos and avoiding looking straight down help disguise sparse lawn grass

     It’s tempting to imagine that this time I’ll really work on that lawn, improving the soil with compost, reseeding, and pampering the new grass with frequent watering. It’s never happened before, but this could be the year. 

     To be a sustainable gardener, though, I resolved NOT to pour resources into lawn grass. Mowing, fertilizing, and extra watering all make lawns environmentally undesirable.

Just about any other plantings are more environmentally sound than a lawn

     Last year I became aware of a major problem for this supposed grassy area—me. I walk over it constantly on my way between the garden, the house, the tools in the garage, and the compost piles in the utility area. The soil is well and truly compacted. What’s to be done? 

Clover, dandelions, plantain, and crab grass predominate in the compacted lawn

     Now that I think about it, the neighbors who maintain lovely lawns stay off them. But not walking on this section of my yard isn’t an option. I could aerate the soil, but my footsteps would soon pack it down again. I could replace the whole lawn with gravel or stone pavers. I don’t want to take on the never-ending job of keeping soil and weeds out of gravel, though, and paving the whole section seems excessive, as well as expensive.

Gravel is kept clean in this British garden. They make it look easy.

    I considered an approach I’d have thought completely philistine until recently—artificial turf. In 2014, my sister-in-law Jennifer Gilbert Asher, a garden designer and sculptor in Los Angeles, tore out the lawn around her swimming pool and replaced it with recycled artificial turf. Her reason was southern California’s longstanding water shortage. I thought she was heroic, but I still couldn’t see it for New England. That was before the Northeast’s 2016 drought.

    This month I noticed some good-looking green grass around a building owned by our electric utility. I’d walked by the place many times and never recognized that the lawn was artificial. I can see why it fooled me, because the “grass” is deep green, soft, and doesn’t look plastic. 

Artificial turf in Florida. It looks a lot better these days.

     Jennifer laid her artificial turf on a layer of sand, which I think means that her lawn doesn’t include the toxin-containing “crumb rubber” layer that’s used in artificial athletic fields. Of course, it doesn’t require mowing, watering, or fertilizing. 

     There are negatives, though. Artificial turf doesn’t provide the animal habitat offered by a natural lawn. It might heat up uncomfortably on summer days. When it came time to remove the polyethylene artificial turf, it probably wouldn’t be recyclable.

    Jennifer replaced her front lawn with a thick layer of arborist wood chips. That might be my best option for the area around the deck. I could replace part of the lawn with low-growing perennials and make some wide wood chip paths to get me where I need to go. 

More wood chip paths could be a solution

Then I could stop feeling bad about this pathetic grass and focus on plants that are more fun.

Coming soon--spring bulbs

Sunday, February 5, 2017

Doing something about the weather

I thought snowdrops blooming this week were the earliest I’d recorded, but looking back I see I spotted some on January 31 in 2012, another winter with very little snow.

Snowdrops are blooming early

In recent years, I’ve noticed spring growth starting earlier. Scientific data confirms this trend is affecting wild plant populations. Our climate is changing, and gardeners are on the front lines.
Witch hazel buds are already opening

     I’m finding the lack of snow cover ominous this year. Is this the new normal? Last year demonstrated the kind of damage that our plants suffer when they experience blasts of cold weather without the insulating protection of snow.

    The New York Times recently reported that farmers in Kansas are talking about changes in the weather, although many still don’t blame human actions for causing global warming. One farmer they spotlighted also spoke about sequestering carbon in the soil. On a much smaller scale, that’s something we can do too in our backyards. 

     Brooklyn Botanic Garden offers The Climate Conscious Gardener, a handbook of useful approaches for minimizing the carbon footprint of your garden and sequestering carbon in your soil and plants. 

    With Congress and the Trump administration rolling back restrictions on methane leaking from oil and natural gas rigs and wells, it’s even more important for us to seize the opportunity to be good climate stewards. 

     Methane is a greenhouse gas 21 times more potent than carbon dioxide. Federal regulations restricting its release were intended to fight climate change. Now with climate change deniers having their way, oil drillers and frackers hope to be spared the trouble and expense of preventing methane release. The planet and everyone on it will pay the price.
Gas flare from North Sea oil drilling--photo by Varodrig

    Some of the steps the BBG handbook recommends:

Planting trees. We’ve all heard about this as a way to keep carbon out of the atmosphere. Long-lived trees are best.

The dense wood of this tall white pine sequesters lots of carbon

Siting trees and shrubs to provide windbreaks and shade. This will reduce your house’s energy needs for heating and cooling—and save you money. 

Minimizing digging or, even better, switching to no-till gardening. When we dig, we introduce oxygen that speeds up decomposition of organic material, releasing carbon into the air.

Recycling fallen leaves and garden waste as compost. When you keep organic material at home as compost, you’re holding onto carbon. 

Applying organic mulches. Mulches made from materials you can get close to home are especially carbon-thrifty. I like to mulch with shredded or whole leaves and arborist wood chips.

Wood chip mulch holds carbon

Shrinking your lawn
. Every other landscape feature requires less energy, petrochemicals, and water for maintenance.

Skipping peat-based potting mix
. Peat bogs are a major carbon sink, sequestering more carbon worldwide than trees. When peat is extracted, carbon is released, and the carbon sink it provided is lost. It’s easy to make homemade potting mix from compost and coir (coconut fiber).

By following some of these recommendations, we can be part of the solution locally, even when the federal government is going in the wrong direction globally.

Neck deep in the Big Muddy