Diversity and Change

In yesterday's post I ended with the thought that diverse habitats, whether natural or human, can change in ways that are beneficial. I suggested that ecosystems, and not just species, evolve over time so that change is part of the   landscape whether we are considering a forest or a city.

I'd like to pursue those thoughts a little more and focus on the question of urban diversity. Numerous scientific studies have shown that diverse ecosystems are "healthy" ecosystems, in that they can regenerate after disasters (like a flood or fire), ward off pathogens (like a disease that could wipe out a single species), and resist invasive species. Can we say the same thing for urban environments?

I've been pondering about my own city, Cambridge, Massachusetts. When we moved here from San Francisco in 1988 we encountered a community that seemed to burst at the seams with incredible, vibrant diversity. Whichever way you looked at it, from economic structure to ethnicity, Cambridge was, to put it in biological terms, a "hotspot" of diversity.

Over the past decade or so this has changed. Cambridge now has fewer children, fewer schools, fewer elderly, fewer artists, and fewer working class families. At the same time, we look good on paper. Higher tax revenues, better services, and a healthier environment than ever before. From a social perspective though, I wonder how healthy we are.

Can our community accommodate social evolution for families with children? Are our educational institutions stronger, or do relatively privileged families continue to pull their children out of public schools? Do we manage our land resources appropriately, or do big pharm corporations (who do pay those taxes) continue to take a wider physical chunk of our neighborhoods? 

Fifty years ago Cambridge began a long decline as light industries, the basis of our economy, dried up or moved. Along with them a large portion of working- and middle-class families left the city. When we moved here in 1988, just before the ongoing development and real estate bubble, Cambridge was considered by many people to be a dangerous, crime-ridden community. It had lost its economic base and much of its urban fabric. A new economic base has emerged and along with it, an urban fabric of a much different cloth than the one that was here half a century ago. We are richer in some ways but poorer in others. As the diversity of our community continues to erode, what is the outlook for our urban ecosystem fifty years down the road?

Forest Change

When we wander through the woods we tend to take in the view as unchanging and permanent. The living forest is actually a landscape in flux, a complex of species, climatic forces, soil, water, and light that exist in a kind of swirling ever changing mosaic.

There are many ways to take in all this action at a manageable level. Tromping around in the Maine woods near Victor's place I came across this small grouping of young white pines in the middle of a stand of hardwood species.

During the summer these pines are stuck in the shade of their leafy neighbors. But in the winter, once the leaves have fallen, the pines have full access to light. Thanks to their internal anatomy and a suite of chemicals that keep them resistant to freezing, the pines are able to do photosynthesis, albeit at a reduced rate, during the winter.

They grow slowly in comparison to their neighbors but eventually, either by growing taller or if a neighbor dies, the white pines become the dominant tree. All through the woods you can see this. The interaction of species with one another and with their landscape is ongoing, part of the evolution of the ecosystem.

Yesterday I wandered around the city with a couple of architect colleagues and pondered a question related to the forest ecosystem. Urban neighborhoods are complex entities that change over time through a combination of geography, human culture, and wear and tear. Looking at the forest as an example, can we plan built environments that change gradually, maintaining their diversity and dynamism over the long run?

A warm night in November

The evening after Thanksgiving. All is quiet in the neighborhood. The evening sky a pinkish blue with fluffy clouds. Warm air slips northward along the coast as it is pushed by a cold front to the west. For the moment the air is almost still. No birds, no rustling leaves, hardly a breeze. Just a moment to appreciate the half moon, the fullness of nature, and the temporary existence of our lives.

The warm night before an inexorable cold reminds us that our condition is fragile. Time passes. Seasons come and go. Our lives intertwine with others temporarily and we are gone like a flash.

Invasive Species and the Changed Landscape

We've read and heard a lot about invasive species. They are infamous for taking over where native species once were common. It's understood that the "invaders" outcompete the "natives" for a variety of reasons. And the general consensus is that these non-native or "exotic" species are somehow undesirable.

One thing that most of us don't think about is how long humans have been introducing "non-natives" to the landscape. It's arguable that as long as our species has existed we have participated in the movement and transplantation of exotic species from one part of the globe to the other. Certainly when transcontinental travel picked up in the 15th and 16th centuries new the rate of introductions increased. By the 20th century there were few if any places of human habitation without introduced species.

Another thing we don't think about is that most of the species we transport are small. Invisible invaders have changed the landscape more than larger organisms. I was thinking about this last week when I was up in Maine at Victor's place.

The prettiest little chestnut trees were lit up by the morning light in the understory of the forest, their dry brown leaves rustling in the gentle wind. I remembered that these small insignificant and rare trees were once the dominant species in the eastern woodlands of North America. What happened?

In the early 20th century some decorative trees from east Asia were brought to grace the grounds of the New York Botanical Gardens. The trees carried with them a fungus that was inconsequential to its natural host, but which soon spread to the nearby chestnut forests.

The microscopic fungus invaded the vascular tissue if the chestnuts, literally choking the trees with a proliferation of fungal growth. No chestnut was immune from the fungus which spread to the entire eastern chestnut forest. Within a decade. small and large trees alike were killed and the landscape was permanently changed as the chestnuts died out and other trees took their place in the first canopy.

Chestnuts resprout from underground tissue. The small ones we see today are the resprouted clones of older trees. They may survive for 10 or 20 years above ground, gathering energy and thriving but never making it to maturity. Ultimately microscopic fungal spores find their way to the young trees and cause their premature death.

It's kind if a sad story but one that tells us about how species interactions can work to alter the landscape. It also drives home the fact that the natural history of introduced species has been going on for longer than we might expect, a history with unexpected microscopic players like the fungus that destroyed the chestnut forest.

Hanging On

Moving into Thanksgiving week. I spent a long weekend at Victor's place on the Maine coast. It's always a treat for the visual senses up there. When you get to Maine you discover that all the leaves have fallen. The only green that remains is in the conifers.

But a closer look reveals something different. You have to get out of the car to see it. You have to spend some time walking and listening to your own footsteps. As a trained botanist I always look down and that's part of the strategy too.

When you get to the coast the water is a sheet of still beauty. Looking around in the underbrush shows you that there are still plants with green leaves. Even this late in the season. Seeing these leaves holding on reminded me; fall is long in coming to the Northeast. Even though the sun has faded and even though there have been several frosts there are plants whose leaves continue to hang on.

Do they continue to provide nutrients for the plant this late in the season? Are they protecting next season's tender buds? Or are they just a response to a relatively mild microclimate next to the water?

The living leaves remind me that beneath the dead looking tissue there is still life. There's plenty of life under the still unfrozen ground also. LIfe hangs on even when the circumstances seem less than optimal. It's a good reminder to stay optimistic.

Water Doesn't Stop

A weekend full of water. Watching water in streams and rivulets. Watching water on the pond. Feeling the strength of tides filling up the basin and emptying it out. The ocean waves crashing or purring while sheets of water disappear under the sand.

Water whether we see it or not is in flux. The endless array of its molecules touching attracting repelling shoving and pulling in a ballet if chaos. Water moving up the vessels if plants toward growing tissue in a sea of cells. Water in its silence or in its noise shouting whispering trickling or dripping.

Water in a thousand forms. As I observe water I interpret its movement as an agent if change. In constant flux it is the medium of movement, promoting growth, in every cell if every plant. Breaking, carrying, washing the physical world.

Sunlight

I spent part if the morning putting Victor's woodpile in order. He asked me to put the older logs on top of the pile and I was happy to help. There's something about stacking wood that I like better than anything else.

Later Victor put together a great fire. I think it's one of his favorite things to do. Something that connects him to his place here in Maine in a visceral, physical, active way. I guess it's connected to the enjoyment I get stacking wood, maybe the same thing.

Looking at the fire this time of year is amazing. An experience in reflection and transmogrification. The light around us is fading but the fire burns bright. The trees have lost most if their leaves but the ones that remain seem to be in fire. The branches and trunks, though bare, are alive.

And the fire? It's captured sunlight, gathered through decades of photosynthesis, stored in the woody tissue of the tree. Inert until it's introduced to fire. Through combustion the energy of sunlight is released to us providing light and heat in a controlled burst of flame.

That Great Fall Sky

Those hours and days when the trees are covered in yellow and orange. Leaves are falling fast and the light shines through the branches. An explosion for the visual cortex. Reminder of the season.

Tearing Down and Building Up

Watching the ginkgo I planted ten years ago grow taller and more mighty. I've trimmed it once already. Tried to weigh down the branches so it would look curved like the wonderful "sport" at the Arnold Arboretum. Healthy tree that it was, it sprouted from the bent branches ever upward.

This past year it grew more than 6 feet. With the look of a maturing tree it spread its branches and took on the unmistakable form of the conifers to which it is related.

I could let it grow forever. Such a lovely tree. Alas we live in the city and our garden is as big as a postage stamp. Conundrum. Let the tree grow past the second floor bedroom window or allow some sunshine into the garden?

Based on my past experience with this tree I decided to give it a radical haircut. The branches were so healthy and supple I could barely cut them off. Sorry to say but it didn't give me one bit of pain to cut this beauty. The tree responded in kind. Here is a picture of it. You can barely tell it was cut. It's raring to go for next year.

I learned something else by trimming the tree two years ago. I stuck one of the young branches in a pot and it has given me leaves for the past two years. Looks like we have a new ginkgo coming along.

So I had an idea. Why not stick some of these young twigs in the ground along the fence and start myself a new hedge? So that ginkgo can regenerate in two ways. The tree I trimmed will grow as good as new next year maybe all the way to the second story. And the twigs I stick in the ground will give me hope for the years to come. Maybe one or two of them will sprout.

It sounds trite but it helps to tear down if you want to build up.

What Does Nature Provide?

What does nature provide? People have looked at this question from every angle I think. I decided to go through my flickr site and pick out three recent pictures of plants and sort of brainstorm about what I saw. I would love to hear how you interpret these pictures with the perspective of the question of this post...

The first picture I chose is this Ansonia plant growing in my front garden. It's a wonderful perennial that has strange blue flowers every June. Now in the fall it looks a little wild and floppy, but it's one of my favorite plants in the garden. If I were to choose one word about what this plant offers, it's vibrancy. The incredible way Ansonia catches the light inspires me to think about how sunlight works its way through the garden at different times of year and at different moments of the day. I was so lucky to plant Ansonia right here because it has thrived and continues to provide us with year-round enjoyment. Not bad for a little thing I bought a few years ago at our local half-price-last-days-of-fall garden center sale. 

The next picture I chose was taken a couple of weeks ago right after Hurricane Sandy. I had just come out of my sculpture class at the MFA and suddenly beheld the wonderful oaks that line the sidewalk at the Fenway entrance.

More than anything these terrific oaks gave me a feeling of being sheltered. A sense of presence with something bigger than me, something with its own distinct form, outside of and perhaps more important than my own, provided me with a sort of transcendent understanding of how nature defines our world. 

What you don't see in this picture is that the oaks had shed huge amounts of biomass onto the lawns and sidewalks by the MFA. The steady winds of Sandy didn't do any real harm, just deposited about a foot of detached tree leaves, twigs, and acorns onto the ground. The stately manner and seemingly calm demeanor of these trees belies the fact that they had been well shorn the night before. 

My final picture is another look at trees, this time at night. This is a luminous ash tree right in my neighborhood, a shot I caught on a mild evening during a rare after-dark walk.

The tree in this picture provides something from both the pictures before. The luminous play of light on leaves as well as the sheltering presence. Somehow this shot also reminded me that nature provides us with a home.

The smiling branches, the sheltering leaves, the life that's found in a busy neighborhood. All of these are amazing contributions that plants bring to our life. Maybe in future posts I'll explore the question of what nature provides in greater detail. I'd love to hear your responses to the question.

...and Snow

We had a surprise snow last night as part of a complex Nor'easter hot on the tail of Hurricane Sandy. Snow covered the sidewalks and streets, and even more so the plants in our garden that hadn't yet lost their leaves. 

It's easy to think about snow as destructive, a harbinger of the cold season to come, a hassle complete with slush and ice. But I try to see the snow as a different sort of phenomenon.

This past summer we got to see a Hopi corn field in the Four Corners region of Arizona. The place being something of a secret, not normally seen by visitors' eyes, complicated arrangements were made to take us to an out of the way spot accessible only by gravel road. The sun was out and it was very hot. The sere ground in every direction looked empty and without vegetation. This wasn't the corn country I knew from the midwest. 



When we got to the field it was nothing like I had ever seen, a truly amazing moment. Bundles of young corn plants were growing together in points four paces from the next bundle. The crop, we were told, was planted this way to avoid competition for scarce water. Out of eight seeds planted about two plants were expected to make it to maturity.

There are many spiritual aspects of corn planting and harvesting that I won't discuss right now. Suffice it to say the the photo I'm showing here was not from that field, but from a visitor center some miles away, where it was just barely permissible to take pictures. That gives you some idea how close the spiritual relationship is between the people and their crop. 

The subject here is snow and the garden. And the Hopi corn field is more a garden than an acre of farmland. The most amazing thing I learned there is that in the spring, the farmer digs way down in the soil, between eight and 12 inches, to find the moisture from last winter's snowmelt. The seeds are dropped all the way down and covered with sandy soil, which means they have to supply enough energy to the emerging plant to make it all the way to the surface before photosynthesis starts.

I've taught about the physiology of seed germination for years and before this I never imagined planting any seed so deep down. The Hopi corn seeds have been bred by generations of farmers to do the unbelievable job of growing to the surface from an incredible depth. 

All this says something about snow and our relationship to it. Here in the East where we have plenty of rain all season, snow is a nuisance. Ecologically it plays a role of insulating the soil and the slowly emerging plants at the surface, but in terms of the moisture it provides snow is not that significant. From the perspective of a farmer in the Four Corners who is planting without irrigation, the winter snow holds the key to next year's crop. 

Corn came to the Four Corners from as far as Central America. Down in the highlands of Chiapas in southern Mexico, I saw it growing straight up the hillside to the rainforest. Moisture in Chiapas is abundant and available year-round.



As corn migrated north humans learned new ways to grow it successfully. They did more than subsist, whole civilizations thrived with a diet of corn as their basis. Humans have grown corn with and without irrigation for thousands of years. One of the gifts of indigenous Americans to the world is that they are geniuses at farming. For generations they have observed their landscape, recognized it as a sacred gift, and used it with respect. As we face catastrophic climate change in our time we should think long and hard about how to grow and nurture crops in accordance with the environment.

Regeneration

They grew tall and gangly. Exuberant from the early days of summer they threatened to shade out more "desirable" plants in our small city garden. I was gone for most of the summer and by the time ideas back on August was too late to cut things back. I kept a reluctant eye on a garden that seemed to have run amok.

Summer turned to fall as the days got shorter and light seemed to disappear from the narrow space that is our garden. One plant kept growing.

In late September they started blooming. Our 10-12 foot tall Jerusalem artichokes caught the light high above the shrubs and bulbs long spent. Their perky yellow heads kept coming high up, almost to the second floor of our houses, a kind of aerial garden.

Sandy came with lashing winds and the last of the Jerusalem artichokes lay in a pile waiting for the yard waste bag. Just a few days ago all that was left was the cut off stems, place markers for my fall "farming."

When things dried up I went out with a stout shovel and started digging. The sandy berm I built and planted with Helianthus tuberosus was chock full of underground tubers. Ready for salads, soups, or roasted vegetables. But biologically speaking, ready to start up again in spring.

The wonderful thing about gardening is having a chance to observe the plants close up. What an amazing thing to see the beginnings of next year's regeneration fast and snug in the soil.

I'm writing this first thing in the morning after the election. I am so buoyed by the results. Lies and calumny and selfishness didn't win. The American people somehow saw through the thicket and voted to regenerate our society. There are so many issues that need to be addressed and now with a continued mandate we can hope that the president, our legislators, and the judicial can make progress toward a more just and fair society.

As the Leaves Fall

I was speaking with my friend peggy Lynch while we waited on line first thing this morning to vote.  Peggy was rushing off to work right afterwards. She does landscape design and we met when I taught my "Botany for Designers" course at the Boston Architectural College last fall. 

Peggy had just gotten a call from one of her assistants who told her yes, he remembered his gloves this morning. It was below freezing and she wanted him safe and comfortable.

"I've avoided buying a leaf blower so far," she told me (yay Peggy!!!) because I want my clients to pile their leaves on top of their flowe beds for compost. "But if we don't blow the leaves I need someone to help rake them up for me."

Peggy reminded me how useful leaves are as a mulch ingredient. They act as insulation but also, as they are broken down by microorganisms, they release nutrients of all sorts into the soil. Even if most of the micronutrients, minerals, and proteins have moved from the leaf into the rest of the plant before the leaf falls, there are plenty of nutrients that don't translocate.  Even if the leaf were all carbon compounds like cellulose (there's lots more in fallen leaves) the dead leaf has plenty to give back to the soil.

All good stuff to remember as we out our gardens to sleep for the season and get ready for the spring bulbs to pop through in a few short months.