The great temperate rainforest of southeast Alaska, dark conifers marching down the steep slopes to the shore and receding ridge after ridge into the distance, often seems to be the soul of the region, the indispensable character of this land. But the forest is everywhere interwoven with the sea, the waters we travel, the home of the whales, the source of the rain of the forest. And here, beneath the gray-green swells, between the islands, lies another forest just as rich and beautiful and mysterious.
Tall columns reaching toward the light, delicate banners unfurling and fluttering in the current, and life everywhere, clinging and creeping on every surface, diving and swirling through every space, this is the kelp forest. Here the ‘trees’ are huge stands of bull kelp and though they are not really plants they are directly analogous to the trees in the forests of shore. Sixty feet tall or more, they are anchored by root-like holdfasts which cling to the rocky bottom and maintain their position in the correct depth. This is important because, like plants, kelp is photosynthetic and must keep its leaf-like blades near the surface so that they receive sufficient sunlight. Though the trunk – or stipe in this case – is flexible rather than rigid, the blades are held aloft by the buoyancy of the bulb-shaped float which is filled with metabolic gases.
Just as in the rainforest where moss and lichen festoon every branch of the trees, kelp also provides a place to grow for many other organisms. But here lies a significant difference from the world above the waves, because many of these ‘epiphytes’ are in fact epizooids, animals like bryozoans and cnidarians which spend their lives clinging to the kelp. Many other creatures also find a home in the kelp forest, in the encrusting community which, like underbrush, covers the bottom, or sheltering among the stipes and blades like the birds and small mammals among the trees. The key here is structure: the kelp provides a complex, three-dimensional place to live just as trees do and this creates a great variety of homes and roles to be occupied by other members of the community, a wonderful variety of life, growing and feeding on one another, layer upon layer, each element adding further structure for further elements.
Today I put on my diving gear and took a stroll in the submarine forests of Alaska, recording what I saw on our digital video camera. I had planned to invite everyone to join me on this excursion during recap but it will have to wait for tomorrow – there are just too many whales around us right now and the evening is too beautiful to come inside.
