Twisted pines and many questions

Why the spiral grain?

Strolling on snowshoes around the Lower Loop at Eaglecrest one gray, damp day, we found, as expected, that conditions forreading animal tracks were bad on the rain-packed snow. So we counted trees instead: we had noticed previously that some of the dead or dying pines in the meadows had very twisted trunks, mostly with an upward twist to the right. So this time, we counted the pines with right or left twists and also checked whatever dead hemlocks or spruces we encountered. This informal, unscientific survey produced a series of questions, largely unanswered.

As a curious naturalist, I find it great fun to generate focused questions, even if I can’t answer them. This essay is an example of how the process goes.

–Is there something particularly about pines that produces the markedly twisted trunks? The other conifers in the Juneau areaoccasionally show such marked twists (but seemingly fewer in proportion to the total population of those species) and we have the impression from other observations elsewhere that deciduous tree trunks don’t generally twist like these pines do.

–If the twists occur predominantly in pines (that casual observation should be verified, of course), perhaps there are intrinsic factors, such as differences in the cells that make the wood, that predispose pines to twist. The principal wood cells of conifers do differ from those of deciduous trees, but do pinesdiffer from other conifers? Or perhaps there are environmental factors, such as exposure to wind and snow, that contribute to twisting? We would need to find a good sample of pines that grew in more protected circumstances to examine that possibility.

–We noted that most of the twisted pines have right-twists. Along one section of the Lower Loop, Righties outnumbered Lefties more than fifty to one. However, a casual check along the CBJ Crow Hill trail found very few twisted pines and there were proportionately more Lefties there.

So now the questions can be asked: Is the predominance of Righties due to some factor of genetics (or very early development)? Is there some environmental difference between the two locations that contributes to the very different frequencies of different twists? Or is it an accident of genetics and who happened to colonize Crow Hill vs the Lower Loop?

–As luck would have it, on the return loop, we spotted a long-dead tree, probably a pine, that had broken off near the base,exposing a central core of straight-grained wood surrounded by many layers of twisted wood. Something apparently had changed as the tree grew—the older growth rings made straight wood but the later growth rings made twist. But what?

It can be frustrating to generate lots of questions for which we have no ready answers, but it is good fun to think about the complexities! Attentiveness to things around us as we walk andthinking about the things we observe adds richness to our strolls.

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This and That

sundews, pines, spider and bees

In early June, I went with a few friends to check out some muskegs at Eaglecrest. In addition to the common round-leaf sundew, we found some long-leaf sundews already making flower buds. Both of these diminutive species supplement their income by capturing hapless small insects on sticky hairs on their leaves and digesting their victim’s juices. There seem to be minor differences in their preferred habitats: longleafs are more likely to grow on soils less densely covered by mosses and other plants. For some reason, perhaps habitat availability in part, longleafs seem to be much less common than the other sundew.

Sundews are not our only insectivorous plants. Butterworts grow in the meadows on Douglas, for example, and in the subalpine meadows on Gold Ridge. Their leaves are sticky traps for insects. Bladderwort is a delicate, fragile aquatic plant sometimes found in muskeg ponds; it captures tiny aquatic creatures in ingenious little bladders with a narrow opening. The opening of each bladder is guarded by trigger hairs; when disturbed by a passing crustacean or insect, the triggers signal the bladder to open. The walls of the bladder are held inward under tension, but when triggered, the walls expand, and the lowered pressure inside the bladder sucks in the victim. Nifty!

While we were exploring the Eaglecrest muskegs, we also noticed that some of the shore pines bore tiny red rosettes near their growing tips, usually on the upper branches. What???? Not some other organism that has taken up residence there. I was sure I’d seen these bright rosettes before, but any knowledge of them seemed to have fallen through the ever-widening cracks in what used to be my memory. However, after a bit of discussion, we settled on the right answer—these are brand new seed cones! Other shore pines bore clusters of pollen-producing male cones, just at the right time to pollinate the new cones.

contorta-flower-kerry-howard
Photo by Kerry Howard

Reproduction in pines is a complex business that includes many seemingly strange delays. The new seed cones were initiated the previous fall but don’t emerge as rosettes until spring. Only the upper scales of the red rosettes bear fertile ovules. When the scales of the rosette open up, a drop of fluid appears near the ovule; this is called a pollination drop. It lasts two to four days, and then it is withdrawn, pulling in any pollen brought in by the wind. The rosette scales then enlarge and close; the receptive period is over. However, the pollen does not germinate immediately, and fertilization of ovules occurs about a year after pollination. Then the embryos develop over the following year, and the seed is filled with food for the seedling. However, pollen from another individual tree is more likely to result in viable, filled seeds than pollen from the same individual. Then the seed cone scales enlarge, and after two full years, the seed cone is mature and ready to shed its seeds.

So, if (and that’s a big ‘if’) a twig makes a cone or two every year, observers might see the red rosette at the tip, then a small cone or two where last year’s shoot tip was, and below that, a mature cone ready to shed seeds in fall. Older cones that have long since shed their seeds may still cling to the twig farther down.

Shore pine cones take two years to mature, but there are other kinds of pines in which cone development takes even longer, as much as six years! But why?? For comparison, seed cones in spruce and hemlock mature in the year they are pollinated. What ecological factors account for the great differences in the ‘strategies’ of cone maturation among all these related conifers?

A few days later, a beautiful brown spider, with gold stripes on its long abdomen, clung to the top of a beach-rye seed head. As I watched, it crept out into the space on the eight-inch journey to another seed head, seeming to walk on air. I could see that two of its legs were prodigiously long, far longer than the other six. Then it fussed about on the second seed head for a short while, moved down an inch or two, and slowly came back to the first seed head. Of course there must have been some silk strands in place, but I could not see them from any angle of view, they were so fine. The diligent spider then seemed to lay down some vertical strands across the existing horizontal ones, working on an invisible web. I would like to know how the first horizontal threads were laid down across that sizable gap. I don’t know her name, so I can’t look up anything about this lovely beastie.

The next week, I perched on a log in the sun, with a clump of beach pea on one side and a stand of lupine on the other. Several small worker bumblebees visited the lupines, erratically checking out a flower here or there on different inflorescences, zooming off a little way and then returning. Occasionally, one would open a flower, pressing down on the lower lip, but never stayed more than about one second. Was that time enough to sip some nectar or was this a sign that no reward was available? If nectar rewards were present, why were the visits so erratic?

 

What a contrast with the behavior of a big, fat queen bee, who was all business. She went straight to the beach peas and systematically visited every open or nearly open flower in the clump. Her behavior suggested to me that she was regularly rewarded for her visits—otherwise, why stay

Pines

some tidbits about a lesser-known local tree

On a nice winter day, a cluster of Parks and Rec hikers perched for lunch at the edge of a beautiful muskeg. Someone observed that many of the shore pines were rather stunted and often crooked, while others grew straight and tall. Our local shore pines are a distinct subspecies of lodgepole pine, which grows mainly in the Interior; its straight, tall growth form gave the species its common name. Some of these Interior-type lodgepoles are reported from the north end of Lynn Canal.

The question, that day, was whether or not the tall specimens in our muskeg might be strays from up north. Someone remembered that there are subtle differences between the subspecies in the orientation of the cones on the branches. But without a detailed genetic analysis, this notion probably cannot be ruled out—after all, these pines use the wind to disperse both pollen and seeds, and who’s to say that no genes from the upper Lynn Canal population have ever come to Juneau.

On the other hand, we observed that the tall, straight pines in our muskeg grew chiefly along the edges, near the surrounding spruce and hemlock forest. This distribution suggested to us that maybe the growth form is determined by habitat; for instance, muskeg edges tend to be dryer than the main part, and perhaps the acidity is somewhat less, too. A little research, back at home, revealed that expert plant ecologists have come to the same conclusion.

shore-pine
The “contorta” subspecies. Photo by Kathy Hocker

That little discussion reminded me that pines are interesting in several ways. I have room to deal with one of them here.

About forty species of pine occur in North America (out of over 100, worldwide). Most of these produce seeds with well-developed, flat wings; they are adapted for wind-dispersal when the cones open and shed the seeds. Just a few kinds lack wings altogether or have extremely small wings.

The best-known North American species with wingless seeds are the several closely-related species of pinyon pine. They grow on poor soils in dry areas of southwestern U.S. and Mexico. The seeds are large, over a centimeter long, and well-endowed with highly nutritious endosperm (about 60% fat) to fuel the growth of seedlings. When the seeds are mature, the cones open but hold the seeds on the cone scales, not releasing them to just fall to the ground. This is considered to be an adaptation for seed dispersal by birds, principally pinyon jays and Clark’s nutcracker, although scrub jays and others also participate. The birds harvest ripe seeds from the handily open cones and commonly cache them all over the landscape, sometimes may kilometers away from the parent tree. Many of the cached seeds are retrieved and eaten by these birds with excellent memories, but some are lost—and these can produce new trees for another generation. Squirrels don’t miss these tasty bites, of course, but they are mainly seed predators. Any fallen seeds—and some cached ones—are scarfed up by rodents, quail, and other ground foragers, including humans.

Pinyon jays and Clark’s nutcrackers both have very strong bills, for hacking open closed, green cones early in the season, before the cones open. Both species have special anatomical adaptations for carrying loads of seeds to caches. The upper esophagus of the jays expands when it is packed with seeds; as many as forty pine seeds can be carried at one time. Clark’s nutcracker has a pouch under the tongue where dozens of seeds can be carried. Both of these birds eat other kinds of seeds too, as well as insects and other foods, but the relationship between the birds and the pinyons is considered to mutualistic—with benefits to both sides. Less specialized birds, such as scrub jays, participate in the mutualism, but the relationship is less specialized.

Two additional pine species (limber pine, southwestern white pine) in western North America make seeds with vanishingly small wings; their seeds also dispersed by caching birds. Seeds are released from the cones when mature and are available then to ground foragers. The seeds of the southwestern white pine are eagerly harvested and cached by Mexican jays, which cannot open green cones well and apparently eat more acorns than pine seeds.

One more North American species (whitebark pine) makes wingless seeds. But in this species the cones do not open readily. This species grows in montane forests of the western U. S. and British Columbia, where seed-harvesting birds and squirrels generally have to open the cones to extract the seeds. The caches of these harvesters are regularly raided by black and grizzly bears. At least in some areas and some years, this food source contributes significantly to the survival and reproductive success of the bears.

Wingless pine seeds also occur in Eurasia, where winglessness seems to have evolved independently several times. The spotted nutcracker there participates in a mutualism similar to that in North America., but the Eurasian jay seems to be more closely associated with acorns and beechnuts (as is the blue jay of eastern North America). Who else might participate in a mutualism with wingless-seeded pines in Eurasia?

Another question: What are the historical and ecological factors that determined the lack of wingless pine seeds in Southeast, where the seeds of all conifers are basically dispersed by wind?

January bushwhacks

the trials and rewards of wilderness yoga

January brought us unseasonably warm temperatures and lots of rain. The once-lovely snow turned first crusty and then punky and rotten. Heavy rains put a serious damper on hiking too—post-holing on soft snow, even on snowshoes, while getting totally drenched is conducive to grumbling and grousing and whining, but not to just staying home.

One little expedition went to a wet meadow fringed with a few million bent-over alders. This required lots of bending under, clambering over, and twisting around. Snowshoes often slid down under the bowed branches, tipping the hiker into sudden lurches and bad words. Curiously, there were no animal tracks or signs to be found, even though these abounded in many other places. We saw one shrike in the top of the scattered spruces. I did see one interesting alder: it had eight trunks, all of which had been snapped off at different times in the life of the tree, most recently by a snowstorm this winter. This tree says “Never, never give up!’ But we’d had enough of alder yoga, and we bailed out.

A few days later, we ventured into a snowy muskeg along the Eaglecrest road. Compared to the alder thickets, this was easy going and much livelier. Lots of porcupine and deer trails wandered about. A flock of crossbills chattered as they swept from one big conifer to another. We saw several eagles and three or four ravens, all flying uphill, and wondered what would draw them there. Many of the shore pines bore knobby infections of western gall rust. This fungus-relative does not kill pine branches by itself, but it gets a secondary infection by a different fungus that does kill the branches. We marveled at some of the tiny pines, no more than two feet tall, that nevertheless bore a cone or two. Small does not necessarily mean young for these trees; indeed, some of the little pines may be quite old. What is interesting is that a tree that is forced by conditions to grow very, very slowly still has some resources to devote to reproduction.

In the middle of January, we decided to look for a reported trail that leads to the top of Goat Hill. I don’t think we found it (but we now know better where to look). Undeterred, we bushwhacked our way up, toting snowshoes for use on the snow in the little muskegs at the top. Fortunately, this was a nice, partly sunny day (unlike almost all preceding days in the month), or else getting repeatedly whipped in the face by seemingly malevolent bushes all aimed at hikers going uphill, and stumbling through spiny devil’s club stems, or punching down through the punky snow into hidden rivulets might have discouraged us. Deer sign was evident all over the hill– tracks and scat and dwarf dogwoods neatly browsed by foraging deer, and their trails provided occasional help in negotiating the messy understory. We persevered and found the cluster of small muskegs at the top. Then the snowshoes earned their keep.

By the time we reached the top, we didn’t have time to explore all the little muskegs, but in the biggest one we found several things of interest. Porcupines had recently gnawed on hemlock bark, and we found partly chewed spruce twigs they’d dropped. There were old footprints of a bear and of a large canid (wolf, or maybe dog). A low, rocky ridge wound through the middle of the muskeg, and here I found some nice red lingonberries, slightly shriveled but still tasty. The miniature gardens of mosses and lichens were gorgeous. One such mini-garden on a broken snag held sodden body feathers, stripped off a hapless bird by a hungry raptor that perched there to get at the meat of its prey.

Too short a time on top of the hill! There would have been more to be found in this un-trafficked place. But we bushwhacked our way down—much easier than going up, since the bushes aren’t out to get you. After this little junket, the creaky old bod knew it had been somewhere…

Visiting Gustavus

observations on geese, raptors, otters, and the effects of moose browse

One of the first things I noticed was a roadside muskeg in which the shore pines were in sorry shape, with many brown needles. Upon inquiry, I was told that these pines are infected by a fungus that causes needle blight. The fungus kills off mostly the older needles, so an affected pine has only small tufts of newer needles near the branch ends. A serious level of infection can kill the tree. Cool, wet weather favors the production of spores, which are spread by wind or rain-splash, and the spread of this disease. And that’s the sort of weather that has prevailed this spring, it seems.

A flock of several hundred white-fronted geese loafed peacefully in someone’s back yard, while an off-shoot group foraged nervously in a nearby field. These birds were on their way to the nesting ground on the tundra up north. They were enjoying an important way-station on their journey, where they can feed and rest.

A pair of Canada geese seemed to own a piece of pasture, apparently unruffled by grazing horses. But they reacted sharply when a little flock of other geese came in to graze. The small group of new arrivals was a mixed lot—mostly white-fronts, a couple of Canadas, and a sole snow goose. The residents paced back and forth, talking at the unwelcome visitors, who went right on grazing but did not venture much farther into the pasture.

The great outwash plain created by melting glaciers supports numerous stands of willows, most of which have been severely browsed by moose, such that they seldom exceed three or four feet in height. ADF&G has a long-term study of moose ecology and the effects of moose browsing, focused on a set of exclosures that prevent moose access. The willows inside the exclosures look markedly different from those outside: the inside willows are much taller and produce more catkins. The paucity of catkins on the heavily browsed willows may have extended effects, well beyond the diminished reproductive capacity of the willows themselves. Willow catkins are an important source of food (pollen, nectar) for queen bumblebees, which mate in the fall and overwinter in small burrows. In spring, they need to feed so they can produce broods of workers. Bumblebees are important pollinators of blueberries, beach pea, lupine, and many other flowers. So the obvious question is: Does moose browsing significantly reduce the spring food of queen bees, thus reducing their ability to produce healthy broods, and thus impairing the pollination success of various flowers?

bull-moose-young-browsing-on-willows
Photo by Bob Armstrong

There may be other ripple effects of moose browsing. For example: Browsed willows produce fewer leaves and therefore less leaf litter below the shrubs. So we can ask if the reduced leaf litter affects the mosses, lichens, grasses, and herbs that constitute the ground cover. A lower number of leaves on the browsed shrubs should reduce their growth rates, because fewer leaves mean a reduced capacity to synthesize carbohydrates that provide energy. And one has to wonder if the cropped-off willows offer fewer nest sites and foraging surfaces for birds, leading to a lower density of birds than would occur in unbrowsed stands.

A male harrier coursed up and down the deeply incised channel of a tidally-influenced river that runs across the outwash plain; he was probably hoping to snag a shorebird or two. I heard snipe, high in the air, doing their flight display: as they swoop around, the rush of air over the spread-out tail feathers is modulated by the beating of the wings, producing a characteristic sound known as ‘winnowing’. Snipe winnow both on migration and on the nesting grounds, and most of these were probably still in migratory mode. I also think I heard a pygmy owl, tu-tu-tu-ing in the trees. A male robin carried a beakful of worms to his chicks, proving that the robins thought it was spring despite the raw, cold weather.

Another treat was the opportunity to watch three river otters exploring one of the inland ponds near Bartlett Cove. I suspect this was a family of a female with two of last year’s offspring, although there was not much difference in size. Otter families often stay together over a winter and into the next spring. These otters were well aware of our presence and kept bobbing up to peer at us. I was told that river otters are often seen as they travel considerable overland distances in Gustavus, visiting inland ponds (are there fish to be caught??) and returning to the ocean shores.