PHOTO BY BERETT WILBER
Standing on top of one of the Pyramid mountains, gloved hands stuffed into my orange raincoat, I look out over a sea of pink and yellow clouds as the sun sets on the low evening ceiling that settles over Sitka Sound. Alaska is not always the easiest place to call home, but moments like these make me forget the rain and cold. They fill me with awe that presses out against my ribs, bringing up a line from a James Wright poem, A Blessing: "Suddenly I realize that if I stepped out of my body I would break into blossom."When the sun shines in my hometown, Sitka, I know I am in the most beautiful place on earth. Sitka is a bustling rural metropolis hugging twenty miles of shoreline on Baranof Island, in Southeast Alaska. The southeast "panhandle," sandwiched between British Columbia and the Gulf of Alaska, is made up of eleven hundred islands called the Alexander Archipelago. Baranof is one of the largest, reaching one-hundred miles long and thirty miles across at its widest point. Like almost all of the other large islands, Baranof is covered in mountains and has year-round ice fields at high elevations.
Southeast Alaska is in the Tongass National Forest. Just shy of seventeen million acres, the Tongass is the largest national forest in the country, and is part of the largest area of temperate rainforest on the planet. Temperate rainforest is a very specific and interesting ecosystem, defined by high annual precipitation, mild climate, and tree populations that do not require fire to regenerate.
Fifty degrees and overcast with a seventy percent chance of rain could be the forecast any day of the year in Sitka. Sitka gets about eighty seven inches of rain per year, and there are other towns, both north and south of us, that get up to one hundred-fifty inches annually. Rainfall varies throughout the region due to mountains and wind patterns.
Climate also varies throughout Southeast, but in general it is pretty mild. The ocean keeps the islands cool and wet in the summer, and warm and wet in the winter. Air temperatures range between forty and sixty degrees fahrenheit in the summer and twenty to forty degrees in the winter. Warm Japanese ocean currents keep the water around forty-five to fifty-five degrees, depending on the season.
Finally, temperate rainforests have little to no forest fires. In some places, like California, fire is part of the life cycle of the forest that allows plants to regenerate and be productive. In Southeast Alaska, wind is the change agent that keeps the forest going. In October and November, our stormiest months, straight winds of up to eighty or ninety miles per hour sweep through Southeast, taking out power lines, keeping people off the water, and blowing down trees. When trees get knocked over, the canopy opens up, allowing young trees to grow and providing light to the ground cover plants. The fallen trees themselves become "nursery logs," providing nutrients to new trees and plants.
While Southeast is not the dramatic icy tundra that many people imagine when they think of Alaska, its majestic mountainous islands make it beautiful in its own way. The mountains are one of my favorite features of the islands, and they have an interesting history. The islands did not all form in the same way, but are the result of a few different geological processes that gathered together over millions of years. At one point, the whole area was covered by glaciers, resulting in the topography we see today.
The Alexander Archipelago is made up of three different types of islands called Wrangellia, Stikine, and Alexander. Two-hundred and twenty million years ago, all three "terranes" were scattered off-shore, separate from each other. The Stikine terrane, made up of volcanic flow, paleozoic sedimentary rocks, and marine sandstone, probably started out as a chain of volcanic islands much like Hawaii. As the plates shifted 200 million years ago, the chain collided with ancient North America at what is now British Columbia. Wrangellia also started as a volcanic chain, but these islands sank below the surface and became a shallow reef covered by marine shale. After a while a rift in the ocean floor produced a large amount of volcanic basalt that covered the reef. Later still, copper was deposited on Wrangellia, and that is why today, the Wrangell mountains have copper deposits. The Alexander terrane, distinguished by its marble and limestone, joined up with Wrangellia off shore in the Middle Jurassic period. Together they made a subterrane that collided with the North American plate in a region of subduction. The collision caused metamorphic and igneous rocks to be formed, and the was begining of the region's mountains. Over the next 200 million years the land continued to shift, with rocks being added, and some rocks breaking off, forming the archipelago. Today the mountains are still growing, possibly rebounding from ancient glaciation or as a result of continued subduction. The Alexander Archipelago is defined by its deep channels and steep mountainous islands. The channels, like Chatham Strait, often mark fault lines between chunks of islands. Their depth, and the dramatic contrast with the mountains, is a result of ancient glaciation. At the height of the ice age, Southeast Alaska was covered in thick glaciers that scoured the islands down to bedrock. The only exposed habitat, called refugia, were small areas of coastline and rocky nunataks that stuck up above the ice at high elevations. Both types of refugia were islands of rock in a sea of ice, and supported life, including mountain goats and bears that still inhabit the islands today . When the glaciers melted, the channels flooded and the tops of the mountains became islands. Looking across Baranof Island on a clear day, you can pick out the sharp rocky peaks that must have survived above the ice, as well as the rounded mountains that were scoured down and made smooth by the heavy ice. There is a lake south of town, Blue Lake, where the deepest point is actually below sea level, probably because the valley was once hollowed out by ice.
It used to be believed that the islands were totally inhospitable during the ice age (Wisconsin glaciation), and all flora and fauna populations arrived and spread in the past 10,000 years . However, because of fossil findings, we are now fairly confident that refugia supported life during the ice age. Sea level was about 300 feet lower, and the coastline was lifted in response to the pressing down of the ice. This created the coastal refugia where plants and animals survived. These areas existed on islands we still see today, but it also connected some landforms that are now separated by water. Fossils of black and brown bears have been found in caves along the coast, dating back to the time of the ice age. Arctic fox, caribou, and ring seal bones have also been found in coastal caves, which leads scientists to believe Southeast Alaska used to look a lot like Northwestern Alaska does today. No polar bear remains have been found, but ring seals are their main food supply, so it would make sense that they would have been in the area as well. 
During the ice age, species were isolated and then they distributed in different directions when the ice melted. In this way species variation developed. Coastal brown bears and grizzly bears are the two main subspecies of brown bears, but depending on who you talk to there are up to ninety subspecies. Coastal brown bear DNA is surprisingly close to polar bear DNA. Baranof Island had some coastal refugia during the ice age, and today the coastal brown bears on the island are their own subspecies . Brown bears live on islands in the northern part of the archipelago, while black bears inhabit southern islands. After the ice age black bears spread south and inland, and the interior bears are now a distinct subspecies separated from the coastal bears, but by studying their lineage we can trace their movement and separation over time .
Southeast Alaska is not biodiverse, but it very diverse in the sense that there are many different ecosystems that exist closely with each other and form complex relationships. There are old growth forests, muskeg, alpine, coastal estuaries and more habitats that are home to many of the same flora and fauna. Because the same species exist throughout the ecosystems, the connections between animals and their environment can be seen, and sometimes they are surprising. The relationships between species and habitats also accentuate the impact of global warming in the Tongass.
The warming of the earth is a global phenomenon that disrupts localized ecosystems around the world. According to a study done by U.S. Fish and Wildlife, Alaska's seasonal average temperatures have increased by as much as 5.6°F from 1949 to 1998. In Southeast Alaska, the temperature in the Tongass has gone up by 1.5-3°F in this time. The most warming was seen in winter and spring, and the only cooling was recorded in the fall . The impact of climate change in Southeast Alaska is clear, but it can pop up in unexpected ways.
For example, let's look at salmon. There are five types of Pacific salmon that spawn in streams throughout the Tongass. Around Sitka, there are a few pink salmon streams, a king salmon hatchery, and a great sockeye run at Lake Redoubt which is just a boat ride away. When salmon spawn in late summer, they return to the same river where they hatched, and swim up all the way to about the same spot where their parents spawned before. If they are not caught by fishermen or bears or impeded in some other way, they bury their eggs under the gravel in a hole called a redd, and then they die. The eggs have to survive in the streambed through winter, and in the spring the baby salmon hatch and grow until they are ready to swim out into the ocean. They live in the open ocean for one to seven years, depending on the species, and then they return again to their original stream to continue the life cycle. Global warming, however, is bad news for salmon populations. Because of global warming, the temperature of the streams has been increasing, and precipitation patterns have been changing. In the past few years Southeast Alaska has experienced periods of drought that are believed to have affected whole generations of salmon. A study done for the North Pacific Anadromous Fish Commission, in 2009, looks at cases of poor pink salmon returns and their correlation to changes in climate. The pink salmon returning in 2006, which would have been eggs in the run of 2004, saw unpredicted low returns. According to the study, "Drought conditions and high stream temperatures in the late summer and fall of 2004 may have contributed to the poor year-class strength of pink salmon." The drought conditions in late summer would have meant less water in the streams, making it difficult for salmon to swim up river. The warmer water may also have presented a challenge to the eggs that were laid. They concluded that "poor marine survival as well as adverse freshwater conditions affected the 2006 returns." Three years later, in 2009, Sitka experienced a warm dry summer that caused concern among locals that we would have another poor fishing season down the road . I remember that summer because it was "the summer of the bear." The early returning pink salmon (salmon who come from parents who returned early in the season will also return early) came late and couldn't run upstream when they normally do because of the poor stream conditions. The bears (coastal brown bears) were not aware of the change in schedule, so they came down off the mountains in August just like they always do, expecting to gorge on salmon. Instead there were no salmon, and no berries either because of the dry weather. Grumpy and hungry, more bears than usual found their way into town. A mother with four cubs caused quite a lot of excitement around Sitka. Outside of town we saw bears everywhere. It was the summer of the bear. The returns in 2011 (the generation of eggs from the 2009 run) were not poor at all, if you look at the pink salmon harvest data recorded by the Alaska Department of Fish and Game . However, the same data reveals that every return of the 2004 salmon descendants has been poor (2006, 2008, 2010). It is probably only a matter of time before climate strikes again and debilitates another batch of salmon.
Salmon are full of nutrients that bears store to make it through the winter, and the same nutrients support the terrestrial ecosystem in the Tongass. In Southeast Alaska there are over 5,000 salmon streams. Because there are so many streams, "47% of the forested area within the Tongass falls within 0.5km of a salmon stream and over 90% within 5km" . Research is still being done on the effect of salmon derived nutrients in the Tongass. So far, we know that salmon bring in nitrogen, phosphorus, lipids, ammonia, and other nutrients that are consumed and distributed through many different pathways . Studies have been done to try and trace salmon-derived nitrogen (15N) and carbon (13C) isotope distribution in the Tongass, but it is a challenging study. It is almost impossible to trace the phosphorus, but that doesn't mean it is any less important. The problem is that we still don't really know how salmon derived nutrients are used by in terrestrial ecosystems in the Tongass, but there is no doubt that they are there. At this point it is hard to know how the forest will be impacted if salmon populations continue to decline, but it is undeniable that, like so much of the world, these systems are intertwined with each other.
I would like to think that if everyone could wake up in the morning and see what I see outside my front door, more people would be passionate about conservation. Our social habits that are detrimental to the environment would be easier to change, because if you can love a place, you will want to make sure it is always there. That's how I feel about Sitka, but I'm lucky. I grew up in a place where you can't avoid the smell of spawning salmon, and bear sightings are small town gossip. The mountains are literally right outside my door; I don't even have to get in a car, I can just climb to the top, eating blueberries along the way. I'm lucky that I can love my place first hand, when so many people don't get the chance to develop a personal connection with the natural world. Even if you aren't from a place, or have never even been to it, you can still fall in love with the mystery and beauty of a wilderness. More importantly, you can share your passion with others and spread appreciation for our planet. While Southeast Alaska is an isolated place of intricate connections, it serves to remind us that the entire earth is made up of a vast web of interacting ecosystems. When human impact disrupts one part of the system, effects radiate out in a chain of related reactions. If the whole world found its mountain sunset, real or imagined, maybe that would be enough to tip the scales of conservation and balance our delicate ecosystems for another few hundred years.
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