The Tongass National Forest: An Ecological Treasure of Alaska
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Chapter 1: The Unique Ecosystem of the Tongass
The Tongass National Forest, located along the southern coast of Alaska between the Pacific Ocean and Canada, is a jewel among America's protected lands. This vast area is recognized as the largest national forest in the United States and one of the world's few remaining temperate rainforests. Its unique coastal and wetland ecosystems play a crucial role in sequestering approximately 8% of the carbon stored by U.S. forests. However, this ecological marvel faces numerous threats that extend beyond its trees. The forest's influence spans from the towering coastal mountains down to the marine wetlands and waterways that border the Pacific Ocean, all of which are increasingly pressured by changes in land use.
Stretching over 350 miles from Ketchikan, Alaska, to Prince Rupert, Canada, the Tongass covers approximately 17 million acres. The forest derives its name from the local indigenous tribes. Its status as a national treasure was formalized in 1902 when President Theodore Roosevelt designated the area as the Alexander Archipelago Forest Reserve. Just five years later, this designation evolved into the Tongass National Forest, which was expanded further in 1909 to create the beloved natural haven we recognize today.
Section 1.1: The Geological Origins
The majestic mountains of the Tongass, remnants of ancient volcanic activity, line the western edge of Canada and extend into Alaska. These mountains are part of the Wrangellia Large Igneous Province, a volcanic formation that erupted around 232 million years ago. The magma and flood basalts from this period formed extensive layers, which eventually became the mountain range we see today. This geological history offers valuable insights into the rapid climate changes that occurred during the Triassic period, leading to significant species extinctions.
Subsection 1.1.1: The Role of Volcanic Activity
The volcanic eruptions that formed the Wrangellia basalts contributed to a warmer climate, with greenhouse gas emissions leading to a spike in global temperatures. These changes had catastrophic effects on coastal marine ecosystems, many of which were lost due to increased sedimentation and heat. The geological formations that remain today serve as a record of this tumultuous period in Earth's history.
Section 1.2: The Impact of Logging on the Tongass
The mountains of the Tongass plunge beneath the ocean, creating a network of over 15,000 miles of rivers and streams that flow into the Pacific. Within this temperate rainforest, trees like Sitka spruce, western hemlock, and Alaska cedar thrive. Unfortunately, these valuable species have attracted intense logging operations.
Initially, logging was limited, but the landscape changed dramatically in 1954 when a major pulp mill began operations in Ketchikan. This marked the start of extensive timber harvesting, which led to the depletion of nearly 90% of the mature old-growth forests by the 1990s. As environmental protections are reconsidered, proposals to resume logging activities are once again on the table.
Saul Elbein of National Geographic highlights the consequences of logging in the Tongass, noting that the destruction of the forest not only alters local ecosystems but also contributes to localized climate change. The removal of trees disrupts the natural balance, leading to sedimentation issues that affect salmon habitats and fisheries.
Chapter 2: Carbon Storage and Climate Management
The Tongass National Forest is pivotal in managing greenhouse gas emissions, thanks to its ideal conditions for carbon storage. A remarkable 66% of the carbon present in the forest is stored in the soil, while the remaining 34% resides in the vegetation. Various environmental factors contribute to the Tongass's exceptional carbon retention capabilities.
The cold climate and high rainfall promote vigorous plant growth and slow decomposition, allowing more carbon to remain sequestered in the soil. This wet environment also reduces the risk of wildfires, which are a significant source of carbon emissions. In fact, U.S. wildfires account for 25% of the annual carbon released by trees.
Section 2.1: The Interdependence of Ecosystems
The connection between terrestrial and aquatic ecosystems in the Tongass is profound. The region receives up to 200 inches of rain annually, which facilitates the flow of nutrients from the forest to the ocean. This nutrient exchange supports a thriving aquatic food web and underpins Alaska's multi-billion-dollar fishing industry.
One vital component of this ecosystem is the flux of dissolved organic carbon (DOC) from Tongass soils into ocean waters. Remarkably, the streams here discharge 36 times more DOC per unit area than the global average and three times more than the Amazon River. This high level of nutrient transport is crucial for sustaining a diverse marine ecosystem.
With commercial logging threatening the forest, the implications for both terrestrial and marine life are significant. The removal of trees disrupts soil composition, which can have cascading effects on nutrient pathways and the health of aquatic ecosystems. Understanding these interactions is critical for assessing the potential impacts of logging proposals on the southeast Alaskan coast.
The second video showcases the Tongass National Forest's ecological beauty and the urgent need for sustainable practices to protect this invaluable resource.
Sources:
- Tongass National Forest (USDA — Forest Service)
- A new way to profit from ancient Alaskan forests — leave them standing (By Saul Elbein; National Geographic)
- Greenhouse Gas Emissions Versus Forest Sequestration in Temperate Rain Forests (By David Nicholls and Trista Patterson; USDA)
- From rock to forest: Southeast’s carbon sink (By Mary Catherine Martin; Juneau Empire)