Suddenly, spring.

April has flown by, with family visiting in the first half, and a trip to Washington DC and Pennsylvania in the second half. Amongst other trips, we enjoyed Boston harbour and the USS Constitution on a cold but sunny day.The Constitution remains a US Navy ship with a naval crew, and visitors are told lots of stories of heroism against the dastardly British in the 1812 war (incidentally started by the USA...). I asked one of the crew how much of the original timber remains - apparently only about 10%, mostly the keel.

USS Constitution, still in  full sailing condition

Jonathan enjoying the best harbour tour - commuter ferries at $3 a trip

After Caroline and Jonathan left to return home I set off for DC, where I had a series of meetings and some time to see the sights in the remarkably compact heart of the city. Everything familiar from tv and movies is within half an hour's walk, although the security was intense in the aftermath of the Boston marathon bombing.  I received an email from Harvard, cancelling a conference due to take place on the day of the manhunt for the bombers which shut down Boston. The title of the conference was 'Confronting Evil',but with a certain black irony the organisers had to do rather the opposite.

The Washington Monument under repair after earthquake damage

The Smithsonian museums are wonderful, numerous and free. I only had time to visit the Air and Space museum, where they have the original Wright Flyer, the first powered aircraft on display. I was also struck by their descriptions of Zeppelin bombing raids on London in WWI - not least because my grandmother had described to me how her family would take cover under the stairs from the same air raids.

 Some Secret Service officers get to wear shorts...

Lots of layers of security around a certain famous residence

From the imperial splendours of DC I drove west into the mountains, to Harpers Ferry, where the Potomac and Shenandoah rivers meet and John Brown arguably fired the first shots of the Civil War. Close at hand was the Antietam Battlefield, where huge casualties were inflicted on both sides for little apparent purpose.

The Potomac from the Harpers Ferry Youth Hostel in spring sunshine

I took the weekend off and biked around the area, stopping at the wonderful Nutter's Ice Cream in Sharpsburg, and climbing up from Cumberland on the GAP rail trail to the Eastern Continental divide, separating waters that flow to the Atlantic and the Gulf of Mexico.

Nutter's Ice Cream in Sharpsburg

The Eastern Continental divide at about 2800' asl near Cumberland, Maryland

 From Cumberland I drove north through the endless suburbs of Pittsburgh to Meadville in NW Pennsylvania. In fact, I wasn't far from Lake Erie, and an alternative and rather easier ride would have taken me to the continental divide just north of Meadville where the giant moraines left by the Laurentian glaciers form a range of low hills as the watershed. These hills are essentially the same structures as the Cape Cod and Martha's Vineyard far to the east - glacial debris forming raised topography. A historical plaque in front of Meadville's courthouse describes it as 'The cradle of the oil and zipper industries' - the oil era essentially started near here where the discovery of a natural oil seep led to industrial scale extraction, drilling and, well, the modern world. Similarly, civilization has been forever altered by the invention of the zipper, so we should be doubly grateful to Meadville. It's a lovely college town as well as a mostly post-industrial centre, and I was welcomed at the Allegheny College for a couple of days of discussions and lectures. Like much of Pennsylvania, Meadville is divided politically between the Democratic, urban, college-related population and the Republican rural surroundings, but there are also significant numbers of far-right survivalist types, preparing for the the takeover by the UN. Bizarrely, the farmer's market here spans the entire political divide with hippie artisanal cheesemakers and organic farmers rubbing shoulders with survivalist types wanting to live off the land and be self-reliant under some future apocalyptic scenario. It sounds like a suitable setting for a modern retelling of Romeo and Juliet...

 A long drive across Pennsylvania saw me picking up some trees from a nursery for a friend in Petersham. Having thought and talked a lot about moving new trees species and provenances to increase the chances of retaining some big old trees in coming centuries, the impending loss of ash trees around Eric's house gave us a chance to explore the practical choices we might make. So I gathered up a dozen oaks and hickories from more southerly origins near Philadelphia and we planted them on a sunny Friday afternoon at his house, and wished them a healthy next 300 years.

The ghosts in the forest

I've mentioned before the extraordinary changes in the New England landscape, from colonization and deforestation to abandonment and the return of the forest. I came across an interesting idea yesterday - that if North America had been colonised from the Pacific coast rather than the North Atlantic, New England would still be a wilderness, never transformed by farming, such is the poverty and difficulty of the soils. Even within the remaining New England population who didn't set off for the midwest, the vast majority 'went downhill' - abandoned the hilltop villages like Petersham and moved down into the valleys where waterpower and later rail access allowed the development of industry (the farming settlements were on the hills and ridgetops because the soils were less rocky).

Everywhere in the woods there remains the relicts of that brief flowering of farming. I took a walk at the weekend in a local reserve called Slab City - as well as farming it was quarried for paving slabs. Largely abandoned in the 1880s.

The 'Night Pasture' - a stonewalled pen to keep livestock safe overnight

I found this old oak rail-fence post. Can it really  have survived more than a century? What purpose it could have served after farming stopped?  

Another old road through the forest, here a raised causeway over a bog

A few of the remaining grasslands have been kept open until more recently near to  the remaining houses. This shows the start of classic 'old-field' succession, dominated by the light-loving white pine spreading out along the old stone wall

A cellar hole - all that remains of a timber farmhouse

It's not only the trees that have returned. Beavers were trapped out well before European colonists started to  clear this area - and in recent decades have been reintroduced to a landscape undammed for more than 200 years.

Beaver dam, Swift River at Slab City. The still water behind the dam remains frozen, and the beaver family have created the swamp behind the ice as their pasture. 

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Maple syrup season

It's maple syrup season, that period of frosty nights and (slightly) warmer days that gets the sap pressure in the trees rising, and allows a simple tap drilled through the bark to produce sometimes prodigious quantities of dilute sugar solution - the raw material for maple syrup. Here at Harvard Forest we have a sap collection project to monitor any patterns in overall sap production over time. These are the sugar maples just below my apartment on Prospect Hill Road.

Our collection trees - at 8am it's still well below freezing, but it will warm up later.

The bolt holding the collection bag to the tree is hollow - this is plugged into the drill hole, and out flows the sap

Yesterday's sap waiting to be collected by Casey and Josh

While the purpose of the project isn't production, it's clearly a shame to waste the sap. Most of it goes to a nearby commercial maple syrup producer, but staff here can have as much as they like. So this weekend I picked up a large tub and got boiling. The sap is a very dilute solution - it's hard to distinguish it from water. While the commercial producers sometimes use fancy reverse osmosis techniques, the rest of us just have to boil. And boil. And boil some more.

Maple sap, (about a third already on the stove)

 I spent about 8 hours on Saturday, boiling the contents of this large bucket in a big stewpot on my stove, with the windows wide open to remove the steam.

Before and after!

The ratio of sap to syrup is about 40-1, although mine may be more since it's not very runny. But it tastes very fine, and I'm looking forward to sharing with family visiting later in the spring.

The exact mechanism of sap production in sugar maples is still the subject of some investigation - not least because different trees seem to vary quite a bit even when they are outwardly identical and on identical sites. As the temperature drops below freezing, sap is drawn up into the branches and the twigs, perhaps due to changes in the pressure of gas-filled cells. The next day, as the temperature rises above freezing, these gas cells expand and the sap flows back down - and out of the tap holes.

Part of the reason for the research is a concern over declining production days in New England as the period of cold nights/warm days shortens with earlier spring weather arriving courtesy of climate change. It seems very likely that maple syrup production will increasingly be dominated by Canadian maples. All the more ironic then, that the new Canadian $20 bill features a leaf that appears to many botanists (and me!) to be the leaf of a Norway maple - a species introduced to Canada and not useful for syrup production. The Canadian government has protested that the leaf on the note is merely 'a stylized blend of different Canadian maple species'. Yeah, right, one that looks uncannily like the Norway maple...

The Coywolf, and other stories

I spent this holiday weekend in a frigid Ottawa, conducting a couple of interviews with interesting people and  visiting family. 

Looking out onto the frozen Rideau canal - comparison below with the same view in September - it's about -16C, and I'm lying in the snow 

 Like any wintry big city, Ottawa was a combination of icy picturesque, and mucky heaps of cleared snow.

Canadian Parliament buildings

The Ottawa River, from shore to frozen shore

Heaps of the stuff...

On my way to Ottawa I saw a coywolf, boldly watching the traffic at the side of the highway. There's increasing evidence that the 'Eastern Coyote' is in fact a hybrid of western coyotes and wolves. The western coyote - much more like a long-legged fox - expanded its range in the decades after wolves were extinguished in the eastern US and Canada. Reconstructions of the genetics suggest that they encountered a remnant wolf population in the Algonquin park in Ontario, and bred to form the foundation of perhaps a new species. The coywolf is intermediate in size and appearance between the coyote and the wolf. 

The coywolf...unfortunately not my picture...

I wrote in an earlier post about the superabundance of deer in the eastern woods. A plausible hypothesis is that these coywolves have been more successful than the 'pedigree' coyotes due to their larger size and  ability to kill deer, and yet avoid the fairytale-based hatred that wolves themselves receive. Essentially, we created a resource, and the flexible canine template has adapted to make use of it. Coywolves are now probably the top predator in New England, and have been found between the cracks in our civilisation, living nocturnally in towns and cities as well as the deeper forests - even recorded in Central Park in New York. There have been some signs more recently of coywolves becoming more wolf-like in behaviour and size, with some isolated instances of attacks on humans, as well as the killing of feral and domestic cats and small pet dogs left unattended. Such a trend doesn't bode well for finding an intelligent balance between the natural world and our determination to defend Fluffy and Kitty with our semi-automatic rifles. Perhaps the answer lies in having really big dogs...

Update...also of interest from the Economist: http://www.economist.com/news/united-states/21573167-coyote-quietly-conquering-urban-america-dogged-persistence

Our Mardi Gras celebration meal in the staff dining room

Meanwhile, further positive news of the advance of modern thinking and enlightenment. The State of Mississippi has just ratified the 13th Amendment outlawing slavery. It appears that an earlier process was not fully completed, and the last step has now been finally completed. This would be a piece of comic bureaucratic bungling if it wasn't for the fact that the earlier ratification process dates back only to 1995. Mississippi clearly needed a full 130 years of reflection before making this dramatic step.

The big snow - Nemo arrives

So, with much fanfare, Nemo arrived yesterday. This winter storm - a classic New England nor'easter - came about with the meeting of two component storms - one moving east across the northern states which provided the cold, and a warmer system moving north easterly up from Georgia, which provided the moisture. By 4pm on Friday we had at Massachusetts-wide state of emergency, and a ban on all road travel.

Through daylight hours on Friday there wasn't much snow:

Mid morning

Lunchtime

Mid afternoon

early evening

 ...the real snow arrived overnight, and by morning the same view looked like this:

breakfast time on Saturday

snow drift above my kitchen windowsill

Our heroic 'Woods Crew' travelled along tricky roads to dig us out - principally to ensure that emergency vehicles could reach the buildings if needed. A great deal of snowblowing:

Ron with a little snowblower, tractor mounted one in the background

The view down the hill - you can see the snow-blast line from the big snowblower on the sugar maples that line the road

Since it didn't look like I was going anywhere by car...

Er, car, snow, you get the idea...

I took to the snowshoes. It will probably be a bit easier tomorrow as the snow packs down a bit. The snowshoes meant I wasn't plunging up to my knees with every step, but I was still sinking deeply, and moving quite slowly. I followed the old road through the 'woods filled up with snow', in homage to Robert Frost.

Big  footprints

woods filled up with snow, and a road less travelled...

For those of us who like the numbers, the snow is lying undrifted about 20 inches deep. Not far away in Connecticut they had nearly double that, 38 inches. The closest place that counts as having records is the city of Worcester, about 25 miles away, where they had the third highest snowfall ever. Boston had its fifth highest snowstorm total, and the highest ever single-day snowfall total. With an icy irony, the blizzard (and the Governor's edict) prevented a number of us Harvard Forest residents from travelling to Amherst, 25 miles away, for an evening watching...indoor ice hockey.

Finally, since this is my 2nd amazing storm event, I'll end with a quote from Weather Underground's Weather Historian, Christopher C. Burt:

'I might add that is a bit unsettling that two of the most significant storms in the past 300 years to strike the northeastern quadrant of the U.S. have occurred within just four months from one another.'

Ice and snow

Very cold! On Wednesday night my thermometer read -21C - a low temperature reasonably common here 20 years ago, but rarely experienced since then. My first experience of it being rapidly painful to be outdoors. A large mass of really cold arctic air moved down from Canada, picking up moisture from the unusually warm Great Lakes, and depositing it as snow. In fact, so hungry for moisture was this dry cold air it picked up enough from the cooling ponds of a nuclear power station in New York State to drop it as an inch of snow in a dramatic downwind plume - as this radar image shows:

There's some rather beautiful ice patterns building up on my windows too:

I spent Thursday in Boston, working in the grand Widener Library, and visiting the Harvard Center for Health and the Global Environment, which is working to raise the awareness of the effects of global changes on human health, particularly of climate change and habitat loss. 

Harvard Yard, Boston. It's -15C!

In the cathedral hush of the Widener Library

Coincidentally, the following day I read an astounding piece of research with results I'm not sure even the authors entirely believed . Ash trees across the Midwest and Canada have been dying, killed by an insect, the Emerald Shoot borer. In many places this has had a really dramatic effect on woodland and urban trees - Ottawa for example has lost about a third of all its urban trees. Now, there's evidence that human health benefits from being in, or near, or even just within view of natural environments, including some work showing that patients recover more quickly from surgery, and need less pain medication simply by being able to see trees from their hospital ward. Quite how this works isn't clear, and may have a range of mechanisms - reduction of pollution, shade and psychological effects have all been mentioned. Anyway, these researchers decided to compare the mortality from heart and lung diseases before and after the removal of ash trees by the Emerald shoot borer. Across the 15 affected states, they found that after allowing for every other change or effect they could think of, the residual effect of the loss of ash trees was correlated with 21000 additional deaths between 2002 and 2007. In the same period, murders using guns in the US was about 50000 - making this little insect a mass killer of humans as well as trees.

As well as being a fascinating piece of research, this is a good example of how science unravels the truth about the world we live in. Other researchers will look at this, check the working, and think about ways to prove or disprove the connection - and to try and understand the causal connection to find out what is really going on. It'll be interesting to follow that discussion. To read the full paper, go to:

http://socialcapitalreview.org/wp-content/uploads/2013/01/donovan_et_al_media_copy.pdf

Predictions – of snow and other changes

I’m sorry for a delay in adding to this blog – Christmas festivities here at Harvard Forest, along with a trip back to Scotland over the holidays, topped off with 10 days of flu which I guess I collected at Boston Airport along with my luggage.

Prospect Hill Road

It’s noticeably colder. My thermometer recorded -20C at new Year, and tonight, after a fresh fall of snow yesterday, we’re expected to reach -16C. In the basement next to the wood boiler is the Equipment Room, full of strange bits of kit, plus a pile of snowshoes. Poking around one weekend (as a distraction from working) I uncovered the stratified layers of snowshoe technology. The upper layer are newish aluminium and fabric, but the lower layers start to include wood and canvas, and right at the bottom are pairs of traditional teardrop ‘tennis racket’ designs. Never throw anything away…Anyway, this weekend I shall try out a pair, and report back on my elegant progress.

Avenue of Sugar Maples

Looking down to Highway 32
I slipped spectacularly on the ice underneath the snow about 30 seconds after taking this picture

Cold for the cows...

It occurs to me that I haven’t fully explained what I’m actually trying to do here. I’ve spent much of my time so far honing my central argument, and now feel confident enough to release it into the wild – and start to talk to forest and conservation managers. So this isn’t a bad time to try and summarize it in the blog. Here goes:

Many of the things we appreciate about trees are provided best (or only) by big, old trees. There are exceptions, of course - nobody wants a 200 year old Christmas tree, and plantation forestry is mostly about growing trees until their early middle age. But for wildlife, shade, water management, landscapes, carbon storage and perhaps our own wellbeing, we need the presence of big old trees. 

I thus started with the view that maintaining and renewing our stock of big, old trees is perhaps the chief responsibility of forest managers, particularly in conservation or multi-use forests. The difficulty is that growing big old trees takes a long time - and for all that time the tree must find its environment viable - i.e. remain within its limits - drought, cold, wind, resistance to pests/pathogens, or combinations of these. So when we select trees for planting (or allow them to regenerate) with the aim of producing some big old trees, we're essentially making a bet that our efforts will be rewarded in 150-400 years' time with trees that have remained within their limits for all that time. 

Our current policy is to promote native tree species, in part because we have evidence that they can successfully live in the required location for centuries - the evidence of that is in front of us. However, I'm increasingly concerned that by promoting the exclusive use of local native tree species, we're making the mistake of assuming that the trees' environment will be as benign over the next few centuries as it was over the last few.

'Prediction is very difficult, especially about the future' - famously attributed to Niels Bohr

There's been a great deal of work done to model and predict the future changes in climate. In the UK researchers in the Forestry Commission have used this data to predict the viability of many of our native tree species, and the news was mostly good - that the expected range of future climates don't seem to be an overt threat to the health of our trees. But the data they used only went up to 2080, and almost no climate forecasts (and no analyses of future tree health) go past 2100. Making decisions for 150-400 years based on predictions for the next 80 years or so seems to me to be extrapolating well beyond what the data will bear, into a period where we cannot know the climates our trees will have to live through. What we are pretty sure of is that substantial climate change is already inevitable,  and that the response of trees and their pests/pathogens is very hard to predict accurately.

So, what should we do, if we can't answer the question 'what will be the viable tree species for the next few centuries'? It seems to me that the only way to approach that problem is by embracing the risks and uncertainty - and that means not putting all our eggs in one basket - i.e. using a diversity of genetic origins, species and perhaps management approaches.

Some forests are naturally diverse, particularly tropical forests. The great north-eastern forest in which I working is pretty diverse too, with 115 main tree species between the Carolinas and Quebec. Any system with such a lot of diversity has - automatically - significant redundancy - that is, species could be lost and the forest will continue to function. Europe's forests are much less diverse (a function of the orientation of our mountain ranges) and my own forests in Scotland are significantly less diverse again. Our Caledonian pinewoods are dominated by our single native conifer, Scots pine. It follows that the loss of any tree species in these low-diversity forests would have an impact much more devastating than in more diverse systems. 

200 year old oaks, dying from drought. Vierzon, Loire, France

 Which, to me, poses some difficult questions of our central woodland conservation principle of only using local native tree species. If that principle leaves our low-diversity woodlands open to future risks of catastrophic failure, perhaps it needs to be modified to accept a wider range of species, including non-native ones. Of course, such 'new natives' would need to have some functional overlap with existing natives. As an example of this thinking, before I left SNH, I made a recommendation that we should stop advocating the removal of sycamore from woodlands that would naturally be dominated by elm and ash. We expect to lose the elms, and the chances seem high that we'll see significant losses due to Ash Dieback. So, these woods may lose both their key canopy species, ash and elm, in the foreseeable future. Sycamore, with its large shady canopy (analogous to elm) and its basic bark pH (elm and ash) has become arguably an asset, not a menace, despite its non-native status. 

This seems to me a good test of my logic, and I wonder what you think?