Dates: Saturday October 11 – Sunday October 12, 2014
Weather: Mostly cloudy/overcast, chilly
Times: Saturday 10am – 5pm, Sunday 10am – 4pm
Locations: Saturday – Nisqually River delta, Mima Mounds; Sunday – Mt. Rainier
This past weekend our class went on an overnight field trip to the southern Puget lowlands and Mt. Rainier. Our first stop on Saturday was at the Nisqually National Wildlife Refuge, which is located at the Nisqually River delta. This area is full of wetlands and mud flats and offers good opportunities for bird watching. We saw many birds there including Swenson’s hawks, bald eagles, Canada geese, mallard ducks, song sparrows, pintail ducks, ospreys, great blue herons, and many others.
The estuary is very rich in biodiversity due to the high nutrient density caused by the mixing of salt water from Puget Sound and fresh water from the Nisqually River. The salt marshes in the foreground of the sketch below fade into mudflats toward the middle of the sketch. This ecosystem is heavily influenced by the tides, as the high tide comes in and submerges much of the landscape, while the low tide leaves much of the landscape exposed. This alternating ebb and flow is what causes sediment to be deposited on the mudflats. Because of the high salinity of the mudflats and the fact that they are submerged much of the time, there aren’t many plants on them. However, there are many different types of invertebrates that live in the mud. These are big attractions for migrating shorebirds, which is what makes this area so good for birdwatching.
The salt marches that are slightly above the mudflats have plants that are adapted to living in salty conditions. One example of these plants is pickleweed, which looks like green spaghetti strewn across the marsh. Pickleweed still grows even though it is often submerged in salty water.
There is an artificial dike through the refuge that creates an interesting divide between the salt water and fresh water marshes. A common plant on the freshwater side is the broad-leaved cattail. Cattails are often the first plants to colonize wetland areas and they enable the settling of sediment to build up the soil.
Farther away from the estuary there is a gallery forest, which is a type of forest that occurs near rivers and streams. This forest had many of the same plants that we have seen in Ravenna Park in Seattle.
It was not surprising to see bigleaf maple here because this plant grows well in wetter areas next to streams.
Here I saw Indian plum for the first time. Indian plums have an interesting strategy of producing leaves very early in spring, much earlier than the other deciduous trees and shrubs. This is a good way to take advantage of available light before the canopy fills in with the leaves of other plants.
There were many interesting animals throughout the refuge:
The wolly bear caterpillar moth likes to cross roads for some reason. They can be seen doing this all of the gravel paths of the refuge.
Close to the end of our visit we had the rare opportunity to see a tornado in the distance! It was spectacular to see it shoot down from the sky and move around a bit before dissipating. Luckily we weren’t near it.
After leaving the refuge we went to see the mima mounds. This is a very intriguing ecosystem at the southernmost edge of where the Cordilleran ice sheet stopped at its fullest extent. There are many theories as to how these mounds formed, but no one is absolutely sure yet.
After staying the night in the cabins at Pack Forest, we ventured up to Mt. Rainier on Sunday. First we stopped for a little bit at Kautz Creek and learned about the effects of the floods and mudflows on the forests in this area. We also caught a glimpse of the top of the mountain.
Next we visited an old growth part of the forest on Rainier. Here again we saw many of the same plants as those in Ravenna Park.
When trees fall over here, new trees will growth on top of them. Because of this, the fallen tree is called a “nurse log”. This strategy gives new trees the advantages of more light from being higher off the ground and more water from the moist log.
The main trees here are Douglas firs. These trees are common throughout the Pacific northwest due to their ability to grow well after disturbances such as fires or wind storms. They are long lived and very tall.
Another common tree here is the western hemlock. This is the climax tree of this forest zone, which means that if there were no disturbances, the forests would have only western hemlocks. These trees are shad tolerant and grow up under trees that colonize earlier, such as Douglas fir.
The Douglas fir mushroom is interesting because it is adapted to grow specifically on decomposing Douglas fir cones.
After leaving the old growth forest we headed up to the bridge that is just below the Nisqually glacier.
From the bridge you can see the end of the glacier where the river begins from the water flowing out from under the ice.
From here we drove up to Paradise. I was here earlier this year at the beginning of July and it was amazing to see the changes that happened at Paradise since then. The whole area was covered with snow before, but now the meadows were visible with many vibrant colors, especially reds and yellows.
Many of the trees here are subalpine firs. These trees do not grow very tall because they would be toppled by snow and wind if they did. They have a distinct conical shape that enables them to shed snow in winter.
Many of the plants at this elevation, including the pink mountain heather, grow fuzzy hair-like parts all over in order to help retain moisture. The hairs create a barrier against the wind, thus slowing the rate of evaporation of water from the plant surfaces.
After exploring the meadows for a while, we hiked to the edge of the moraine formed by the Nisqually glacier.
The view across to the other side of the valley provides insight into the glacial history of this area. First of all, we can see that the glacier used to be much thicker at this point and used to extend much farther down the valley, which is evidence by the U-shaped curve of the valley walls. As the climate has warmed, this glacier has receded from the point of it’s fullest extent, which was below the bridge we stopped at earlier. During the initial advance of the glacier down the mountain, the rock underneath was ground up into pieces that form the glacial till now seen in this valley. As the glacier has receded, it has deposited large boulders called “erratics” all over the area and exposed the lateral moraine walls that were formed in the advancing period. The clear trim line at the top of the moraine divides the part of the mountain where vegetation grows from the part that used to be covered in ice and is still too harsh for much vegetation to colonize effectively.
Finally, we hiked up the Panorama Point just for fun!