Updates to this journal
may be sparse for a time.
Please dip into the 140+
existing posts and pages.

Windthrow

This sensuous tangle is not a strangler fig, nor yet any other alien monster:

DSCF2877fp

~ ~ ~

Flying Squirrel Hollow, as sometime known, lies at the extreme southern point of Farrar Pond, indenting an edge of the glacial outwash plain forming the high ground to the south and west. A minor source of water inflow (nutrient runoff perhaps not so minor?),  it may be located as waypoint 11 on the map here opposite the former Pickman stables. From above, in late spring, the connection looks about like this,

DJI_0169fp_1600

while winter draws back the canopy:

DJI_0061b_fp

(Quadcopter photography courtesy of Dante and Daddy, who are creating beautiful and informative aerial video tours of Town conservation lands.)

Steep banks with superb percolation feed subsurface water year-round to almost two acres of rich, black bottomland, supporting a dense community of ferns, skunk cabbage and other shady wetland vegetation. On slopes and flats higher up, well-drained A and B horizons protect buried wood (like dead tree roots) from dry-rot. This allows upland snags to remain upright for the perching,

S0080012fp

dining

S0318066fp

and denning

P1200470fp

pleasure of diverse birds, mammals and insects. This oak

DSCF2464fp

was killed but not felled by an alarming lightning strike in the early 1990s; this 30-foot chestnut leader—despite the multiplying sail area of a Virginia creeper

DSCF5895fp

has stood at least a decade longer, roots yet viable and new growth productive in the phoenix-like way of its kind, as a testament to Castanea‘s desirability for fenceposts and other outdoor construction.

In the damp valley floor, though, death more briefly precedes destruction. Roots of many species may not “want” to penetrate deeply into waterlogged, anoxic muck, and may also have no need to reach far to satisfy nutritional requirements. Structural support against lateral wind loads is important, as blowdowns are a primary natural determinant of New England forest seniority.  But the Hollow provides good shelter, as well as the collective windbreak of other trees. Comparing exposed roots from blowdowns in the valley and above, these sheltered trees often seem more delicately rooted. So when a deciduous tree here does die standing—from drowning, disease or other misadventure—it is likely to lose its footing in just a few years. This image, of the flatter part of the valley floor, illustrates the point:

DJI_0034b_fp

Most trees stay attached to their root balls. (–Easier to see at ground level). The three large trunks at center right are from one very big white pine: the two with mossy growth fell decades ago, the third recently’ and the resinous stump still stands. And once down, when trunks are not propped out of the wet on side-branch stilts (as with that pine), rot is rapid.

Massachusetts does experience rare tornadoes (a minor one, or possibly a strong microburst, cleared an arable patch in the woods south of the dam half a century back), and the tail end of a hurricane might dump a lot of sideways rain from time to time. But the big winds here are the dread nor’easters, which augment high peak speeds—and strong gusts that dislodge roots and can induce extreme swaying oscillations—with heavy lateral snow loads. So it is not surprising that nearly all of these blowdowns point (yellow arrows) roughly to the southwest. A notable exception is indicated by the red arrow, which crosses the public footpath.

DJI_0034b2

Probably made more vulnerable by entangled-root damage and soil dislocation when its west-pointing neighbor fell several years earlier, this tree—here at right, from direction of orange arrow—

DSCF2867fp

had been struggling for a long time, and had probably lost much of its substructure by the time it fell. But given its previously symmetrical and balanced trunk and branching pattern, why in that direction?

Strong south winds are uncommon here. But there are dramatic exceptions, like the odd extratropical cyclone spinning up the Connecticut Valley. Soaked ground, violent east-side winds freighted with rain… An irresistible force against an inadequately braced object. That underside view, and this lateral one (green arrow),

DSCF2870fp

show the limited reach of major roots. (For comparison, a quick stroll eastward along the pond-side trail shows, via footfall erosion, the length and strength of roots in more exposed locations.)

Also visible is a large vine, which probably had little to do with the tree’s death (unless its clinging opened a path for some pathogen), but was carried down with it. What kind of vine? Exposed masses of hairy rootlets, visible even in dull winter,

DSCF2878fp

are already indicative. But vines are more adaptable than trees, so patience as usual reveals all, and further up the downed trunk—

DSCF5372fp

further still—

DSCF5370fp

and now eighty feet away, on drier ground, with less confusion from the background jungle of June,

DSCF5366fp

we see the recrudescing former top of a healthy Toxicodendron radicans displaying its venomouly glossy moisture barrier as it feeds from the decaying oak. New life from old, and so repeats the cycle.