Category Archives: science of the seasons

Science of the Seasons: Finicky fruits — Defeat defenses to harvest tasty, nutritious rose hips

Photos courtesy Dr. David Wartinbee. Harvesting rose hips can be worth the effort, but watch the thorns, seeds and spines.

Photos courtesy Dr. David Wartinbee. Harvesting rose hips can be worth the effort, but watch the thorns, seeds and spines.

By Dr. David Wartinbee, for the Redoubt Reporter

This fall I was describing to a friend the heavy fencing I had constructed around mountain ash trees to protect them from our local moose herd. She commented that it stands to reason that moose like mountain ash trees since they are members of the rose family. For some reason I had not really considered this aspect of the moose attraction.  No wonder moose are daily visitors to our yard.

Everywhere you look around our home we have methodically planted members of the rose family because of their flowers and fruits. We have dozens of different rose bushes providing beautiful flowers all summer long. Nearby we also have several varieties of raspberries with red or golden berries. Then there are the raised-bed strawberry patches.   In another area of our property is the orchard with dozens of different apples, several plum trees and even a couple cherry trees. All of these, and even the common serviceberry bushes that line the driveway, are members of the rose family. I guess we have planted a lot of “moose bait,” because every one of these rose family relatives are great dinner fare for moose.

A favorite of the moose are the rose bushes we nurture in our yard because of the showy flowers and attractive scents. When the flowers are gone the bushes produce colorful, rounded rose hips where each flower used to be.

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Science of the Seasons: Angelic properties from a devilish plant

Photos courtesy of Dr. David Wartinbee. The bright-red berries of the devil’s club pant are sought after by bears, but humans should beware when brushing up against this prickly plant.

Photos courtesy of Dr. David Wartinbee. The bright-red berries of the devil’s club pant are sought after by bears, but humans should beware when brushing up against this prickly plant.

By Dr. David Wartinbee, for the Redoubt Reporter

Many years ago while hiking on Afognak Island, I first encountered an interesting plant that I came to know as devil’s club. Its huge leaves dominated the vegetation underneath the taller spruce trees. The leaf shape was reminiscent of a gigantic maple leaf with a verdant green color. To top off the bright green, there was an attractive mass of red berries on top of the stems, which gave holiday flair. The woods that day showed a contrasting combination of green shades with red accents.

This was an image I had seen in a painting by artist Byron Birdsall. As fall approaches, the leaves change into a bright yellow shade and the devil’s club’s heavy leaf veins stand out clearly. Then these colorful plants seem to disappear after the first heavy frost. The leaves drop off and only the stubby, tan-colored stems remain.

The scientific name of devil’s club is Oplopanax horridus and the species name gives warning of bad things. The view that day on Afognak Island from several feet away was the best one to have, since there were hundreds of needle-sharp spines completely covering every stem. The beautiful leaves even have stiff, half-inch spines underneath that could impale the unwary. Deer and moose are known to avoid nibbling on the leaves and the many spines, and that’s thought to be the reason. Considering the number of spines I acquired on the front of my legs by walking through the plants that day, this plant was surely the work of the devil. Devil’s club has come by its name honestly.

These plants are well known in Alaska and can be found as far south as Washington, Oregon and even parts of California. Interestingly, they can also be found in some isolated spots as far east as Ontario and Michigan. Devil’s club seems to like moist, rich soils and does well under a mature forest canopy. It is often found along small streams, and the large leaves are known to provide protective shade for animals within the streams.

The genus name of devil’s club includes the name “panax,” which indicates this plant is related to the ginseng family of plants. Ginseng is a staple in Asian and many home-brewed medications. There are many parts of the prickly devil’s club that are used today for food and medicinal purposes.

In the early spring, the very first shoots of leaves that appear are sought after by natural food hunters. Several authors note that the shoots are edible for only a couple days when they are very short because their spines harden quickly and no amount of cooking softens them. The flavor of these greens is described as “tasty” and also “quite unique.” Apparently, deer and moose will carefully feed on these tender, early shoots, too.

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Red alert, seeing yellow — Summer abuzz with stinging bugs

Photo courtesy of Patrice Kohl. Wasps paper a nest hanging in a tree. Stinging insects are particularly active now as they search for food to feed their young.

Photo courtesy of Patrice Kohl. Wasps paper a nest hanging in a tree. Stinging insects are particularly active now as they search for food to feed their young.

By Dr. David Wartinbee, for the Redoubt Reporter

For those of us on the Kenai Peninsula, July and August is the time of year to stock up on salmon. Most of us plan on eating our fresh, canned or smoked salmon immediately and throughout the coming year. However, whenever I am processing fish, a swarm of pesky interlopers seem to arrive for a portion of the catch — yellow rackets that appear out of seemingly nowhere to aggressively buzz around the filleting table.

Yellow jackets are predatory wasps that feed on sweet, sugary substances, as well as on meat. The adults most often feed on sugary things, like sap or flower nectar. But right about now is when they are actively feeding their growing larvae in the nest and are best fed on proteins.

This explains why they can be seen around your flower garden, as well as anywhere there might be fresh meat available. If we weren’t so obliging with our fish cleaning, yellow jacket workers would be scouring the vegetation for insect larvae and adults they can capture, chew up and feed the youngsters.

Because of their insect-hunting behavior, yellow jackets are actually a benefit to gardeners. (I know this is sometimes difficult to remember when they are buzzing all around your picnic table.) Later on in the summer, as the days turn colder and there are fewer larvae to feed in the nest, workers will predominately feed on sugary or carbohydrate foods.

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Science of the Seasons: Summer mosquitoes excel at surviving winter

By Dr. David Wartinbee, for the Redoubt Reporter

There are several dozen species of mosquitoes found in Alaska, and each of them has its own particular life cycle, although all of them are aquatic. Some prefer lakes, others ponds or various marshy habitats. Eggs are laid in the water and hatch out to become “wrigglers,” or larvae. Most of the larvae feed on algae or dead plant materials. They then form a pupa and shortly afterward emerge and become the aerial mosquitoes we love to hate.

The females usually mate and then look for a blood meal — and your arm looks like a great source of that blood. Note that only the females need a blood meal, so those buzzing around your head are all female mosquitoes.

When you and I swat at the mosquito that’s buzzing about, we probably don’t take the time to differentiate the particular species. But each species has its own approach to surviving the Alaska winters.

Many species overwinter as an egg that is laid in water during late summer or early fall. The egg remains underwater in a diapause state of inactivity until spring thaws. In the spring when water temperatures rise, the eggs hatch and the larvae feed voraciously. Within a week or so, they pupate and quickly become the aerial insects we know so well.

Another overwintering approach is for adults to find a safe hiding spot and wait out the cold of winter. Often these hiding spots are within leaf piles on the forest floor, in tree holes or under tree stumps. These areas, especially with a snow cover, provide insulation from the very coldest temperatures of winter.

An important goal for overwintering adults is to prevent ice crystal formation within their hemolymph (insect blood). First they reduce the amount of water in their hemolymph, kind of like concentrating their blood. Then they produce glycerol within the hemolymph, which acts as antifreeze. Now the adult is protected down to some pretty impressive temperatures. This activity is just like what we do to our automobile radiators each winter.

However, if the temperatures around the adult fall below the protected temperature range, the adult will die. Very cold temperatures during a winter with minimal snow cover can reduce the spring population of early mosquitoes.

For overwintering adults, when the ambient temperatures rise in the spring, they are quickly able to leave the hiding place and seek out a blood meal. One particularly large Alaska mosquito uses this overwintering technique so well that it is called the “snow mosquito.” These are usually the first large mosquitoes we see flying around when there is still snow on the ground in early April.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the biology of the Kenai River watershed.

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Science of the Seasons: Riparian areas of real importance

By Dr. David Wartinbee, for the Redoubt Reporter

Photo courtesy of Dr. David Wartinbee. Natural vegetation surrounding Soldotna Creek secures the riparian area as well as provides nutrients to life in the water — namely, insects, which then feed young fish.

Photos courtesy of Dr. David Wartinbee. Natural vegetation surrounding Soldotna Creek secures the riparian area as well as provides nutrients to life in the water — namely, insects, which then feed young fish.

The transitional areas between a water body and the surrounding upland community are known as the riparian zones. Riparian zones are a transition of physical conditions, like moisture levels, light, temperatures and canopy.

As well, there is a distinct change of one plant community into another. Along with the changing vegetation, we see a change in the animal and microbial communities, too. The distance required for this change is highly variable depending on slope, geology and hydrology of the area. In constrained areas, meaning with steep-sloped edges, the riparian zone may be fairly small. However, in many cases, these riparian zones can be hundreds of feet wide.

Riparian zones are often species rich. They can contain more species of plants and animals than the starting aquatic habitats or the upland communities. The reason for this is that the transitional zones have plants or animals from both communities. It is well documented that plants in riparian zones grow more rapidly than similar plants in other areas. Some trees in riparian zones are known to grow at twice the rate of their siblings in upland areas.

Riparian zones play major roles in the biogeochemistry of the nearby water body. It is within the riparian areas that plant material and other debris gets trapped and stopped before entering the water body. Leaves, seeds, twigs, limbs and the like that fall to the ground are rapidly processed here. The transformation is from recognizable biotic debris to inorganic elements that are now usable by plants. These transformations are performed by a large suite of insects, worms and, most importantly, bacteria and fungi.

Leaf contributions to streams, like Quartz Creek, seen here, follow a natural schedule. The nutrients enter the stream in the fall and are utilized by insects and bacteria during the winter.

Leaf contributions to streams, like Quartz Creek, seen here, follow a natural schedule. The nutrients enter the stream in the fall and are utilized by insects and bacteria during the winter.

Research has shown that 67 percent to 89 percent of “upslope litter” is retained and processed in the riparian zone. The remaining elements, like nitrogen, phosphorous and potassium, are now in a form that can be utilized by riparian zone plants. (Notice the numbers on your bag of garden fertilizer — they stand for the percentage of nitrogen, phosphorous and potassium contained within.) This source of nutrients explains why riparian zone plants grow so rapidly.

A major benefit of the riparian zone is to remove incoming pollutants or extra nutrients that would otherwise enter the stream, river or lake. It has been known for years that removing or altering riparian zones results in decreased efficiency in the biogeochemical cycles.

Research has further shown that changes within the riparian zones will decrease the growth rates of community plants, as well as cause a marked decrease in the diversity within the community.

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Science of the Seasons: Keep a hawk eye out for avian acrobatics

By Dr. David Wartinbee, for the Redoubt Reporter

A few weeks back, when the Redpolls were emptying our bird feeders every day, we had a special visitor. Out of the corner of my eye a large dark bird swept low over the ground and headed to an area below one of the feeders.

The feasting Redpolls seemed to scatter in every possible direction and just as fast, the predator was gone. I wondered what had just cruised by and suspected it might have been a goshawk. We have seen goshawks attempt to take small birds at the feeders in the past but this hawk was more dark brown than the characteristic blue-gray back and light-colored chest of adult goshawks.

I started looking out every window of the house in hopes that it might have landed nearby. Sure enough, there was the predator, perched in a tree staring at the bird feeder and the dozens of Redpolls that were back on the ground. It was a goshawk-sized bird with a dark brown back and a speckled front. The eyes were bright yellow and not the ruby red I expected of an adult goshawk. After a quick check in my bird book, I was certain that this was a juvenile goshawk.

Northern goshawks, perhaps better known simply as goshawks, are categorized as an accipiter and are found throughout North America, Europe and parts of Asia. They are a year-round predator here in Alaska but are so secretive that they are only occasionally seen. This past winter I encountered several goshawks but in almost every case, they were quickly out of sight and lost in thick woods.

I was usually able to identify them by their size, gray color and characteristic flight pattern of flap, flap, glide. Additionally, they are one of only a very few hawks that are seen here in winter months. These distinctions work in the winter, but in summer sharp-shined hawks frequently use that same flying cadence and Harlen’s hawks are similarly colored to immature goshawks.

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Science of the Seasons: Bearing study

Photo courtesy of Dr. David Wartinbee. A polar bear rests on a gravel bar near Kaktovik during September 2010. Until sea ice reforms in the winter, bears are relegated to shore.waiting for the sea ice to form.

Photo courtesy of Dr. David Wartinbee. A polar bear rests on a gravel bar near Kaktovik during September 2010. Until sea ice reforms in the winter, bears are relegated to shore.
waiting for the sea ice to form.

Polar bears (Ursus maritimus) are an iconic creature that most of us have experienced as cuddly children’s toys or as friendly family groups interacting with penguins in Coca-Cola commercials.

Much of what we commonly see portrayed about polar bears is quite distant from reality. When viewing TV ads, I always want to point out that polar bears and penguins live worlds apart, penguins in the Antarctic and polar bears only in the Arctic. They only meet in fairy tales. I am also bothered by the anthropogenic portrayal of large family units of polar bears because in the real world they are mostly solitary predators who actively avoid contact with their relatives.

Polar bears are found throughout the northern hemisphere Arctic. There are populations in Norway, Russia, Canada, Alaska and Greenland. Most of their lives are spent as ice-pack hunters, looking for seals that have created breathing holes through the ice, or those basking on the ice. When the sea ice melts in the summer, the bears hang out along shore areas. Typically they fast during this onshore time, although they are happy to take carrion or feed on whale carcasses from Native subsistence hunts. They head back out on the pack ice to hunt seals again, as soon as the sea ice starts to reform.

In Alaska villages, like Kaktovik, polar bears are spending more and more time on land due to the earlier and more extensive summer sea ice melting. And the sea ice is reforming later in the fall than it used to, so bears are onshore longer these days. In these situations, they are not usually feeding, so social interactions are less intense.

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