Glacier Bay, Alaska
From trim-line to tall trees.
Let there be no doubt that forests once covered all of Glacier Bay in a blanket of rich green…perhaps during many different eras. Tall conifers, lush shrubs, flowering plants, mosses and lichens would have prevailed, and birds, mammals and insects would have filled their respective ecological niches. The last was perhaps 3500 years ago, in the warming period before the most recent “little ice age.” This astonishing national park continues to spring back from its most recent entombment in ice. It offers a textbook lesson in plant and forest succession – the slow but inevitable transformation of polished bedrock into a complex community of interconnected plants and animals. As glaciers recede, pioneer plants slowly take hold. Dryas species and the legumes, alders and other nitrogen-fixers are the first to succeed. They create nutritive soil, shade and protection for other plants. Tall trees follow, and with them come the forest dwellers.
We began at the trim-line for our lesson today, those polished rocks that are only now escaping the icy grip of Margerie and Grand Pacific glaciers. As we snaked our way southward, the melding of various seral stages leading to the new forest could be seen. Even high stands of mountain hemlock – relics of the last interstadial period - were pointed out by our National Park Ranger Melanie Heacox.
The gargantuan Grand Pacific Glacier, now blackened with millions of tons of morainal debris, has raced 65 miles backwards, even though it continues to flow downhill. At the southern end of this classic fjord, the trees have now had up to 200 years to grow. Such old growth, adjacent to a beach full of tasty intertidal treats, is a perfect home for Black Bears. It took all of our eyes and most of the day to find a bear, but we did. And not just one, but this rollicking family of four. Silently we watched and laughed at their antics…a truly delightful encounter. May they have a happy life.
From trim-line to tall trees.
Let there be no doubt that forests once covered all of Glacier Bay in a blanket of rich green…perhaps during many different eras. Tall conifers, lush shrubs, flowering plants, mosses and lichens would have prevailed, and birds, mammals and insects would have filled their respective ecological niches. The last was perhaps 3500 years ago, in the warming period before the most recent “little ice age.” This astonishing national park continues to spring back from its most recent entombment in ice. It offers a textbook lesson in plant and forest succession – the slow but inevitable transformation of polished bedrock into a complex community of interconnected plants and animals. As glaciers recede, pioneer plants slowly take hold. Dryas species and the legumes, alders and other nitrogen-fixers are the first to succeed. They create nutritive soil, shade and protection for other plants. Tall trees follow, and with them come the forest dwellers.
We began at the trim-line for our lesson today, those polished rocks that are only now escaping the icy grip of Margerie and Grand Pacific glaciers. As we snaked our way southward, the melding of various seral stages leading to the new forest could be seen. Even high stands of mountain hemlock – relics of the last interstadial period - were pointed out by our National Park Ranger Melanie Heacox.
The gargantuan Grand Pacific Glacier, now blackened with millions of tons of morainal debris, has raced 65 miles backwards, even though it continues to flow downhill. At the southern end of this classic fjord, the trees have now had up to 200 years to grow. Such old growth, adjacent to a beach full of tasty intertidal treats, is a perfect home for Black Bears. It took all of our eyes and most of the day to find a bear, but we did. And not just one, but this rollicking family of four. Silently we watched and laughed at their antics…a truly delightful encounter. May they have a happy life.
