Monday, November 12, 2012

When a hurricane visits a forest

One day I was walking with my mentor in the woods when he asked me ‘Why are all these trees the same age?’.  With his hands in his pockets and a silly grin on his face (as was his style), he stood facing a small clump of young sugar maple trees.  These ten trees –all roughly the same size and age— went unnoticed until Jeff drew my attention to them.  Before he asked about them, they simply merged without distinction into the rest of the forest.  Now, they stood out as a single group with an obvious common history.

What was the history of this group of trees?  What took place to result in a tidy patch of even aged trees?  The answer is in today's post...

I was reminded of that day on a recent visit to Carolin’s Grove, one of the preserves owned and managed by the Pound Ridge Land Conservancy.  Late October's Hurricane Sand visited Carolin’s Grove like she did any other place in Pound Ridge.  The preserve’s namesake—an 80 year old grove of Norway spruce—was torn to bits by the storm.  Some trees were entirely torn from the ground (roots and all), but more commonly they were left standing, splintered and shattered in half.  As I walked through the wreckage my eyes were drawn up to the sky, which now occupied large gaps in the forest canopy where spruce trees stood only a few days before.

  The following was the sequence of my thinking: 
My thought process as I gaze up through a gap in the forest canopy.  

Every so often, something comes along and kills a handful of perfectly good trees and replaces part of the forest canopy with a wide open gap.  All types of catastrophes can cause a gap in a forest canopy: hurricanes, fire, pathogens (i.e., insect, fungi), ice storms, wind storms, lightning, and let’s not forget the good old fashioned ax.  
A view from Carolin's Grove after Hurricane Sandy.  Forest all over Pound Ridge, NY were devastated by her strong winds.  

What happens once a canopy gap is produced?  Typically, trees grow to fill in the gap.  More specifically, a handful of very lucky trees get an extra dose of light and prosper…upward.  Think back to the story at the beginning of this post – could this have been the cause of the ten evenly sized maple trees?

In one sense, last week’s Hurricane Sandy was a perfectly normal forest phenomenon; forests along the eastern seaboard and in New England have been dealing with bad storms for as long as there have been forests.  Sandy represents one piece in a never ending cycle of tree death, birth and growth.  There is, however, something happening in the forest these days which may alter the cycle.  These days, our forests are experiencing a little extra pressure which affects the processes of birth and growth.  Any guesses?

A cute little white tailed deer.  In Pound Ridge, NY white tail deer are so numerous that they prevent any new trees from growing in the forest.  

The current deer density is so high that it suppresses new trees from being recruited into the forest.  For effect, I'll say it in a few different ways: new trees don’t grow in Pound Ridge; trees fall, but new ones don’t grow back; with every storm, our tree count goes down; every day, our forests are getting thinner and thinner; many new gaps go unfilled.  I'll express it in economic terms: we are only withdrawing from our bank account—there hasn’t been a deposit in years.  

Need proof?  Go to the forest behind your house and find a tree less than 5 feet tall.  You'll be lucky to find one.  This is not forests in other places look like. Most forest can replenish their toppled trees, and they do so with a forest floor full of young trees waiting for a gap to open in the canopy.      

I spent last autumn in a part of Maine where logging is the industry.  I spent endless hours exploring the logged forests, learning great lessons in forest regeneration; all places recently cut were home to fresh clumps of young trees, fighting their way to the sun.  I didn’t mind the destruction to the trees because the forest’s future grew roughly knee high and smelled of fresh spruce as I brushed past it.  

Unlike the regrowing forests of Maine, the barren forest floor of Pound Ridge lacks promise for our forest’s future...

Thursday, November 8, 2012

A stranger among your maples

The forests of Pound Ridge, NY are filled with maples and they live in just about every part of the landscape: on wet sites and dry sites, south facing slopes and north-facing slopes, in the shade and in the sun.  We have six maple trees in total:  
Red maple (Acer rubrum).  A very common maple found in wetlands.

Black maple (Acer nigrum).  While it is said to grow in this area, I have not seen it in the wild.

Striped maple (Acer pensylvanicum). This small tree is found in only the coldest places of the area (i.e., exposed, north facing sites at high elevation) 

Silver maple  (Acer saccharinum).  This tree lives on floodplains.

Sugar maple (Acer saccharum). The most common maple around Pound Ridge, NY and the one from which we make maple syrup. 

 Norway Maple: INVASIVE MAPLE. 
This maple tree is not from North America.  Since being brought here it has negatively changed the forest.  

The norway maple is said to be invasive because it spreads quickly through our forest, outcompeting native trees and shading out forest wildflowers.  The tree is also undesirable from a forester's perspective – when compared to the native (and more desirable) sugar maple, the wood of the Norway maple makes poor lumber and burns cooler.

Now, during the second week of November the Norway maple is very easy to spot in the forest.  Now, its yellow and orange leaves stand out against a grey (or after yesterday's snowfall, white!) leafless forest.  In the grand show of fall foliage, the Norway maple is late to the party.  All of the other maples already shed their leaves but the Norway is only just now entering its dormancy.  Below are pictures I took to help train your eyes to this plant.

A Norway maple up close.  Notice that it is the only tree still holding colorful leaves

Large Norway maple trees along side a road.  One in the foreground and one in the background.  

The entire yellow band in the center of the photo is comprised of Norway maple trees.  

Try to spot these yellow trees as you go through your day – you'll be amazed just how many are invading the forest.  I spent a few hours this week girdling Norway maple trees at the Armstrong Education Center in Pound Ridge, NY.  

Wednesday, November 7, 2012

Hurricane Sandy

My heart goes out to all the people who have lost something to Hurricane Sandy.  In these hard times I hope you find support and that your life regains a sense of normalcy soon. 

A little bit of love for the victims of Hurricane Sandy