18 November 2013
Forest edge, overlooking the marsh
It looks like the arm of a colossus, but it turns out to be the giant’s head. The ground must have shook when it fell. The top of the large northern red oak (Quercus rubra) has snapped off and now decapitated, stands only 30 feet tall. Two of the giant’s limbs have been sheared from its body. What has slain this giant?
From where the limbs were once attached I see a giant ruffle of dingy-white to yellowish shelf mushrooms. These are certainly devouring the tree from the inside.
Mushrooms are the fruiting bodies of fungi (a kingdom of life more closely related to you and me than to the red oak). The white and yellow shelf I see is simply the tip of the fungal iceberg. Beneath the bark is a large spreading network of threadlike hyphae – rootlike structures that collect water, nutrients and release wood-dissolving enzymes. This fungal filigree is now slowly gutting the tree.
I need a closer look, because I’m a blanking scientist and this is what we do. Red oaks, however, don’t like scientists climbing on them because they have this pesky habit of not having any David-reachable limbs. I find a rope in my car and throw it over the lowest limb, which is 20 feet up. I’m a lightweight at 140 lbs, but pulling myself straight up is just as embarrassing an effort as it was with my pipe-cleaner arms in gym class. I take off my shoes for better footing and ‘walk’ up the trunk.
On the third try I get to the lowest limb and then hang there in the air, my legs desperate to touch something. I swing my legs trying to get one onto the limb. After much cussing and grunting, I am on top of the limb. I will feel this tomorrow.
The mushroom has a mushroom smell, a pungency of sweetly soured earth. I don’t know what it is but I collect a sample for later in case it’s edible. This mushroom is killing the tree, but I don’t think it’s the first agent of death.
At the foot of the tree, there where my shoes are, is seaside goldenrod (Solidago sempervirens). Nearby is rough cordgrass (Spartina pectinata) and marsh elder (Iva fructescens). These are salt marsh species. Species that are invading the forest.
The phalanx of a rising sea besieges the bastions of the forest edge, felling these giant reds to open up the sky so that the army of marsh grasses can march inland. The mushrooms are a secondary attack, entering the tree where it was wounded as the salt sapped the oak’s strength and stripped its limbs and toppled its canopy. All along the leading edge of the marsh, other giants have been felled, their carcasses abloom with feasting fungal scavengers. In 20 years, there will be nothing in this spot to climb but 6-foot tall marsh grass.
The advancing sea is advancing faster these days. In the past decade, sea-level has risen 6 centimeter in the area at a rate of 6 mm/year (compared to an average rate of 3 mm/year in the previous 90 years). (I explain below how I arrived at this number). The battle between the forest and marsh is lost and won in the length of a pinky. The marsh doesn’t invade because of greed or ruthlessness, it invades to survive.
Like humans, moving to higher ground is a strategy to survive rising waters. This is called ‘marsh transgression’ or ‘marsh migration’ and with accelerated sea-level rise, the marsh needs to migrate landward quickly. In areas where the land is too steep to climb or where there is a backyard wall or a road through a marsh, the marsh will throw itself against the land and the wall desperately as the water rises, like the non-believers against the doors of Noah’s Ark.
For now, this red oak still stands, its insides being dissolved by an unassuming sulfur ruffle of mushrooms. The sea will continue to encircle its base until it pulls both the tree and mushrooms to the ground and the marsh over-runs it. The mushroom, like the marsh, will simply move on to the next tree, following the advancing wave of a rising sea.
Dr. David Hibbet, a mycologist (and a fun guy – I couldn’t help myself!) at Clark University helped me identify the mushroom as a sulfur shelf (Laetiporus sulphureus), also known as, “chicken of the woods.” He, and field guides, say it’s edible. On the phone he said, “Some people can eat it no problem, but for some it causes severe intestinal distress. I wouldn’t give it to anyone really young or really old.” I’m 37 and just been diagnosed with irritable bowel syndrome so I thought I’d take a chance. For science!
The flavor was astringent and bitter. My taste buds said, “Spit it out!” but my brain said, “This is for science!” I chewed for a bit and it had the texture of chewed, crumbled paper in my mouth (I used to chew paper as a kid). My friend Brita said, “I eat it all the time! But I sautee it and it’s good.” Now she tells me. I’m now three hours in and I feel fine. But if I suffer from ‘severe intestinal distress’ later then I don’t know if I should blame the chicken of the woods or the IBS.
http://www.mushroomobserver.org – this is a crowd-source to identify mushrooms.
Field Guide to Common Macrofungus in Eastern Forests and Their Ecosystem Functions – United States Department of Agriculture.
Duley Crabbe, my great friend who is also great at coming up with terms of battle and then patiently explaining what they mean – more than once. Thanks man!
How to calculate sea-level rise from your very own home!
The National Oceanographic and Atmospheric Administration monitors tide gauges all along our coasts (as far back as the late 1800′s!, your tax dollars at work).
-Go to this website http://tidesandcurrents.noaa.gov/ and select a state and then select a tide gauge (I picked Boston because that’s closet to me).
-Then select ‘water levels’. You’ll get a high tide low tide chart.
-Scroll down and select a year range (I picked 1921-2013).
-Select ‘data only.’
-Okay, this part is stupid, but NOW set the interval to ‘month’ after it gives you the “Error: Range Limit Exceeded: The size limit for data retrieval for this product is 31 days” message (if you know a better way to do this, let me know!).
-Select ‘Export to CSV’ and you’ll get an Excel file.
-In Excel you’ll have this wonderful raw data set! Now what to do with it? I use pivot tables. Don’t know how to use pivot tables? Learn. They will save your life when working with big data sets. I averaged Mean Sea Level (MSL) by year and plotted MSL by year. You can get the sea-level rise (SLR) by year by adding a linear trend line and looking at the linear equation. The number before the x is your rate of change per year, or in this case the rate of sea-level rise. Remember that this number is reported in meters so 0.003 m = 3 mm. You can look at different chunks of times to see the rate of sea-level rise accelerating in the past few decades. Have fun!