Pondology
news from the waterfront by Tim Matson

WHEN A TREE FALLS IN A POND

Woods flank my house north east and south, the way they have for forty years, and I can report that I'm hearing more trees hit the ground "naturally" than in the past. Standing outside, working, coming home from a car trip, the hillside will be silent... and then the slow tearing sound begins, picks up speed, I recognize what's happening, leaves or limbs ripping as they fall, and then... smash! Another tree bites the dust. I don't think it's my imagination that more trees are falling because the evidence (blowdowns and drops) is more numerous than before. It's harder to get around in the woods until the fallen trees get cleaned up.

This summer the second of two whites birches close to my pond hit the water. I wasn't outside to witness the fall, but on my way to get the mail, there it lay. The first tree had fallen the year before, so it wasn't a big surprise to see the second one drop a year later. They had sprouted and grown naturally near each other on a slope above the pond, and I had watched them grow from saplings to full grown over thirty years. Expert claims of a 140 year lifespan clearly exceed my trees, and current reality, at least in my experience. Combined with the increase in early drops of all species, I'm inclined to predict shorter tree lifespans in general, and to look at the changing climate for answers.

Perhaps the most obvious contributing factor is the increasingly wet weather we're having in the northeast. Saturated soils loosen root grip, and I can imagine flooded frozen soil also further undermining the roots. I had also seen signs of disease in the branches of the first tree to fall, and there is plenty of evidence from arborists that the wetter weather plus other factors in the changing climate (invasive insects and other pests, etc.), makes our trees more vulnerable to disease than in the past.

Whatever the reason for tree drops, it's something many pond owners deal with, and here are some general thoughts on shoreline trees and dealing with cleanups.

Do you want trees around the pond to begin with?
In my experience it's a rare pond that sits naked in a field without at least a tree or two for a landscape accent, shade, or a rope swing for a leap into the water. Trees are great for creating privacy buffers too. But there are a few things to be aware of when trees and ponds combine. Leaves or needles drop into the water and have the potential to alter water chemistry, add to sediment and nutrient load, and perhaps clog up the pond spillway.

In general, best practice pond construction will
discourage planting trees in a pond dam. The roots can compromise embankment compaction as they grow or rot. And a big tree blowing over can pull up a huge root ball which might damage the embankment or shore. The same goes for allowing trees to naturalize on a dam. Planted or natural, there can be an exception if the dam is very wide and the trees are far back, especially if shallow rooted.

If you are going to be stocking fish, think of what a fine perch (ouch) a tree could make for a predatory bird, especially a kingfisher. Fish-eating birds like cormorants and grebes also use trees as diving perches and/or nests.


A white birch takes a fall in Tim's pond.

But what happens when a tree or big branch does fall in your pond?

I've seen many ponds, usually big ones, with a fallen tree or branch allowed to lie in the water. Usually these trees lie close to shore (where else?), and may offer a platform for a sunning turtle or two. They might provide shade and/or shelter for fish. They give the pond a desirable natural look, if you're inclined that way. Some folks will even drag a tree trunk or a branch into the pond for just that effect.

When it comes to removal I suggest you ask your tree
nicely to fall on the pond in winter when its covered with ice. Dragging a tree over the ice is about the easiest way to move it, whether by hand or machine. The ice should be thick enough to support the weight of tree workers, etc. The internet offers ice thickness tables for various weights.

If you have a tree in unfrozen water, removal might begin with a chainsaw and cutting it up so that logs can be hauled out of the water by hand or with a tractor. Or cable the whole thing out. If the shoreland where the work will be done is very wet, you might want to wait until dry weather, to minimize damage to the land. Dragging any kind of big tree across a shoreland lawn is going to cause damage. To avoid such damage you might get the tree out of the water, for later removal when the ground is either dry or frozen.

Whether the wood is destined for a fireplace, woodstove, or sawmill, save a little to chop for a winter bonfire. Don't forget the marsh mallows.

August 1, 2015

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