Search This Blog

Sunday, September 30, 2012

Silver Trees and Long Odds

The silver trees twist up out of the rock, binding together red earth and blue sky.  The thick fingers reach up as if to catch quick whips of cloud, or grasp at the wings of the ravens.  These trees have clenched the rim of the caldera for many hundreds of years, bearing witness to changing seasons and ultimately, a changing climate.  They are beautiful, and many of them are dead.

 Whitebark pine on the caldera rim, Crater Lake National Park, Oregon.  Photo: J. A. Gervais

The whitebark pine, Pinus albicaulus to its most serious-minded friends, lives at the highest elevations of Crater Lake National Park in Oregon, and in high elevations throughout western North America.  The species has long contended with atrocious weather, swinging between violent storms and forty or more feet of snow each winter at Crater Lake, and then a prolonged summer drought that breaks with the next year's snowfall.  These trees don't even begin to produce seeds until they are in their sixth decade, and only after their first century do they begin producing cones packed with large nuts in any quantity.  Not surprisingly, they grow slowly and are capable of living a long time, at least in the world they knew.  Unfortunately for them, the ground rules have changed in the game of survival.

One of the wild cards that we're gambling with in warming the global climate is the ranges of species.  As conditions shift, some species find themselves unable to adapt or move quickly enough to escape newly hostile conditions.  However, some species are finding themselves unbound, capable of spreading where they've never been before, and often the conditions or other species that kept them in check do not spread with them.  Epidemiologists are already finding evidence of the spread of disease-carrying mosquitoes in many countries, which are putting new human populations at risk of diseases that not long ago were safely limited by biological boundaries.  But it isn't just people who stand to face new and devastating challenges as organisms break free of traditional limits.

 Whitebark pine cone and seeds, which feed many species of birds and mammals. Photo: J. A. Gervais

Whitebark pines are susceptible to a small and unassuming beetle, the mountain pine beetle, known as Dendroctonus ponderosae to entomologists; it is not clear if this beetle has many friends.  The tiny beetles overcome trees by flash mobbing their target, burrowing beneath the bark in great numbers all at once and overwhelming the tree's defenses.  They then let other beetles know that the flash mob has done its work by emitting a chemical signal, called a verbenone, essentially saying the party is over.  Been here, done that.  The flash-mob beetles then lay their eggs beneath the bark of their victim.  When the larvae hatch, their tunneling and voracious appetite for the tree's inmost bark is so great they can kill a large tree in a few weeks by cutting off water and nutrient flow between branch and root.

Beetles have a weakness; they don't like cold weather much, and low temperatures used to hold them at bay from the high country throughout the mountains of western North America.  However, winters aren't what they were, particularly with regard to temperature, and the beetles have surged up slope to attack new targets.  They've discovered whitebark pine, and they like it.

Clark's nutcracker, which depends heavily on whitebark pine seeds.  The birds cache the seeds under several inches of soil, and forgotten caches produce new trees.  Photo: J. A. Gervais

Humans have dealt a doubly bad hand to the whitebark pine.  A century ago, nursery trees from France were shipped to British Columbia.  They carried an undetected stowaway, the fungus Cronartium ribicola, which almost certainly has no friends at all.  The fungus attacks pines, and kills them within a short span of years with a disease called white pine blister rust.  It has finally arrived at Crater Lake.  The fungus kills many trees, and weakens others, making them even less able to withstand the beetles.  Botanists in the park estimate that a quarter of the whitebark pines within the park boundaries are dead, another quarter are dying, and the remaining half face a very uncertain future.

The botanists are doing their very best.  They've been collecting and growing seeds from marked trees and when the seedlings are a few years old, the botanists expose them to the fungus to see which trees have genetic resistance.  They're slowly identifying the very small number of trees who carry the right genes, so that these trees' offspring can be planted and protected to increase this rare type.

A flash mob of mountain pine beetles claimed the tree on the left.  Photo: J. A. Gervais

Unfortunately, fate holds some of the most important cards.  First, the genetic resistance to fungus means nothing at all to the mountain pine beetle.  Trees resistant to the fungus can still be flash mobbed and killed.  Second, the botanists must beat the wildlife to the resistant trees' cones in the first place, lest the Clark's nutcrackers, grouse, squirrels, and bears make off with them first.  On top of that, there is little money to do the work, as is too often the case. A scant hundred trees have been tested so far for fungal resistance.  Many of these have failed the challenge.  Only a few hundred seedlings have been planted to replace the tens of thousands of dead and dying trees.

The botanists aren't giving up, even if the odds are long and the numbers small.  They're busy continuing to test genotypes of trees, identifying as many as they can that might offer the fungus some fight.  They're protecting these trees from the beetle essentially with a bluff: stapling little bags of verbenone to the trunks of those special trees, to fool the beetles into thinking a flash mob has already invaded.  It seems to work at least some of the time.  Those same trees sport bags of netting around the cones on their branches, which will at least keep the birds at bay.  You have to play your cards the best you can, even when the deck is stacked against you.

Whitebark pine with packets of mountain pine beetle verbenone stapled to its bark to repel the beetles, and net bags to prevent animals from eating the cones before botanists can collect them. Photo: J. A. Gervais

Whether it will be enough to win this round in the game is another matter; the odds are probably longer than getting dealt a royal flush, but it beats simply folding and losing this elder species without even mourning it, letting the sudden unbending of boundaries wash away so much that is beautiful, unique, and irreplaceable.  May we all be so inspired by the botanists' example that we find whatever ways we can to play our own cards, because in the game to slow global climate change, every move we make to reduce the damage in any way each of us can increases the odds for our own long-term survival.

Note: much of the information in this essay is from "Can we stop the decline of the whitebark pine?" Crater Lake Reflections Visitor Guide, Summer/Fall 2012.

Tuesday, September 18, 2012

Magic of Mare's Eggs

The suggestion came at the end of the email detailing things of interest in the area, received just as we were loading the car for the trip.  Almost as an afterthought, our friend had typed, "oh, and the "mare's eggs" Nostoc colonies are in the creek next to a roadside turn out."  She then gave us full directions to find them.

It seemed we were supposed to know what a Nostoc colony was.  Fair enough, we're biologists, we of all people should know these things.  We  didn't have time to do our homework as we were literally on our way out the door.  But we thought that anything as weird as a mare's egg, whatever it was, should be immediately identifiable, at least as the thing we didn't recognize.  We pulled into the indicated turnout and followed the path down to yet another beautiful spring-watered pool, which are abundant in the Klamath Basin region of southern Oregon.

It looked ordinary enough as gorgeous spring-watered pools go.  The vegetation surrounding the pool was typical, and there was an enormous beaver lodge, suggesting that water chemistry certainly wasn't outstandingly odd.  The water looked clear and felt tooth-shatteringly cold, also typical of these springs.

It wasn't long before we noticed the rounded grey-green shapes the size of golf balls to baseballs scattered across the sandy bottom of the spring, and realized that they were not stones.  A few of them were close to the spring's banks, and when we scooped one of the odd things up, we found that it was not a hard object at all, but a gelatinous mass with a hollow center.  We carefully replaced it, feeling as if reaching through the surface of the water had suddenly led to a space-time shift, and we'd somehow left the familiar world we thought we knew.  We had innocently wandered down a woodland path to a perfectly ordinary spring on a lovely early fall day, and found ourselves surrounded by organisms that looked like they more properly belonged to a much earlier epoch in planetary history, if not a science fiction movie.

Truth is stranger than science fiction. Nostoc is a genus of cyanobacteria or so-called blue-green algae, although cyanobacteria are neither algae nor blue-green.  Cyanobacteria did start the process of putting oxygen into our atmosphere, however, essentially making a whole new world in the process.  Species within the genus Nostoc live in a wide variety of habitats, from temperate springs to arid environments to the Arctic and Antarctic.  They can lie dormant and undetected for long periods, abruptly gearing up and becoming metabolically active when water becomes available.  They have earned themselves a variety of colorful folk names for this, including witch's jelly and troll jelly, because people couldn't figure out where these gooey blackish-grayish-reddish gobs had come from.  It therefore had to be magical.  This was before the era of science fiction.

Nostoc species are able to fix atmospheric nitrogen, a boon both to the bacteria and the environments in which they live.  These skills make them desirable partners, and they may move in with other organisms, forming symbiotic relationships with lichens, ferns, and mosses.  Species of midges appear to have a symbiotic relationship with one species of Nostoc as well.  The midges lay their eggs on the colonies, which support the larvae until emergence.  The colonies actually change their shape when the larvae move in, which increases the Nostoc's ability to photosynthesize.  This in turn adds more nitrogen to streams that often are nitrogen limited.  Bug makes the shape and metabolism of gooey mass change, which benefits both bug and gooey mass.  Robert Heinlein, did you know about mare's eggs?

Despite the fact that people couldn't figure out where these weird beings were coming from, they ate them anyway.  Or maybe that's exactly why they ate them.  Suffice to say that the Chinese have traditionally enjoyed one species of Nostoc as a special New Year holiday dish, and contributed to desertification of the Gobi as a result.  Peruvians collect Nostoc from the mountain lakes, and eat them or trade them for other food.  Toxicologists are unsure about the benefits of this.  Although Nostoc species have been used in folk medicine for thousands of years, it appears that they contain a highly toxic compound that can melt your liver.

Ironically, the genus was named by none other than the Father of Toxicology himself.  Paracelsus is remembered as a rather difficult character who openly expressed his disdain of the ideas of his peers and colleagues.  Although he emphasized experimentation and direct observation as the pathways to better medicine, he also consulted astrology.  Nostoc might be loosely translated as "star snot."

The species we found in the spring was Nostoc pruniforme, which is both endemic and apparently quite rare in the Klamath region.  This species has done one of the the most amazing things of all: it prompted the Bureau of Reclamation to build a temporary dam to prevent water from one of the few known occupied pools from draining away.  The Bureau of Reclamation likes to build dams, usually to provide water and electricity or just because that's what they do.  I have never heard of them building one at the potential expense of agriculture, all to save balls of star snot.  Maybe they'd heard that mare's eggs were magical.

 Long may we be amazed by the other beings who share our planetary home!