Saturday, November 21, 2015

The Forest Primeval

The first stanza of Longfellow's poem Evangeline sets the stage for a primal forest:
This is the forest primeval. The murmuring pines and the hemlocks,
Bearded with moss, and in garments green, indistinct in the twilight,
Stand like Druids of eld, with voices sad and prophetic,
Stand like harpers hoar, with beards that rest on their bosoms.
As ancient fossil forests are unearthed, scientists gather clues about nascent plant life and the prevailing climatic conditions of the time.

Fossilized forests discovered around the world, dated as far back as 380 million years ago, provide insights into Earth's ever-changing atmospheric composition and the corresponding climate changes on Earth.

During the Devonian some 420 to 360 million years ago, the atmosphere underwent a 15-fold decline in carbon dioxide. The decline is thought to be primarily attributable to carbon sequestration caused by the evolutionary emergence of large forest trees.

Carbon sequestration rates vary by forest age, composition, and location, but today we know that a single tree can absorb carbon dioxide at a rate of 48 lb. per year.

The decline in atmospheric carbon during the Devonian period is posited to have spawned large-scale global cooling that led to a period of glaciation.

Sketch of the forest floor in ancient fossil forest near Gilboa, New York
Frank Mannolini, New York State Museum

Fossil plant-life discovered in Schoharie County, New York in the 1850s, in 1920, and again in 2010, included the Gilboa stumps cited as Earth's oldest trees.
It was like discovering the botanical equivalent of dinosaur footprints. But the most exciting part was finding out just how many different types of footprints there were. The newly uncovered area was preserved in such a way that we were literally able to walk among the trees, noting what kind they were, where they had stood and how big they had grown."
William Stein, Binghamton University, 2010
Researchers have unearthed another forest with fossilized tree stumps preserved in place in Svalbard, a Norwegian archipelago in the Arctic Ocean. 380 million years ago, Svalbard was located near the equator.

Reconstructed drawing
Fossil forest, Svalbard
Since the Devonian period, plate tectonics has transported Svalbard to its current location in the arctic ocean.
"These fossil forests shows us what the vegetation and landscape were like on the equator 380 million years ago, as the first trees were beginning to appear on the Earth."
Chris Berry, Cardiff University
By the phenomena of carbon sequestration, trees absorb structure-forming carbon from atmospheric carbon dioxide through photosynthesis.
"The evolution of tree-sized vegetation is the most likely cause of this dramatic drop in carbon dioxide because the plants were absorbing carbon dioxide through photosynthesis to build their tissues, and also through the process of forming soils."
Chris Berry
Svalbard is also in the forefront of preserving plant diversity. One of the northernmost inhabited villages on Earth, Svalbard is the site chosen by the Norwegian government in 2008 for the Global Seed Vault. Secured in the permafrost, the Svalbard seed vault is the largest seed storage in the World.
"In some mysterious way woods have never seemed to me to be static things. In physical terms, I move through them; yet in metaphysical ones, they seem to move through me."
John Fowles