Winter botany quiz #5

This may be the last winter botany quiz for awhile, but I did come across this interesting little plant on my recent visit to Lake Tahoe that doesn’t fit neatly into any other category upon which I have (or will be) posting about. I was excited to see this plant, and I’ll be interested in seeing what others think about it. Hints: photograph taken on 03/17/2009 at Emerald Bay State Park, along Rubicon Trail, elev. 6,250′.  The host is ponderosa pine (Pinus ponderosa).

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The usual rules – I’ll leave the photo up for a couple days to give people time to research their answer, with comment moderation turned on during that time. Whoever gets it right (or is closest in case nobody gets it right) wins, and being first is always good in case of a tie-breaker!

EDIT 04/20/2009 – Wow, congratulations to, well… almost everyone, for getting this one right. I guess it was not as hard as I thought it would be, since I’d never heard of dwarf mistletoe until I ran into this plant.

To be exact (something I’m fond of being), this is western dwarf mistletoe (Arceuthobium campylopodum, arse-youth-OH-bee-um cam-pie-low-POE-dum). The term dwarf mistletoe refers to the genus as a whole, while ponderosa pine dwarf mistletoe generally refers to what is now called southwestern dwarf mistletoe (A. vaginatum) from AZ and NM. Accordingly, Kirk deserves special mention for being the first to get both the common name (spelled correctly with lower case) and the scientific name, while Doug was the first to properly italicize the scientific name. I know, I’m being really picky – it’s my nature. Also, Adrian added a nice tidbit of information regarding the impact these plants can have on their hosts.

I can be fairly certain about the ID, but not 100%. According to Hawksworth & Wiens (1998), four species of dwarf mistletoe occur within the Tahoe Basin. Of these, only western dwarf mistletoe utilizes ponderosa pine as a principal host.  There is a small chance it could be lodgepole pine dwarf mistletoe (A. americanum), which occasionally utlizes ponderosa pine but is most often (as the common names suggests) associated with lodgepole pine. The two remaining species, fir dwarf mistletoe (A. abietinum) and hemlock dwarf mistletoe (A. tsugense), are restricted in the Tahoe Basin to white/red fir and mountain hemlock, respectively.

REFERENCE:

Hawksworth, F. G., and D. Wiens. 1998. Dwarf Mistletoes: Biology, Pathology, and Systematics. Diane Publishing Company, Darby, Pennsylvania, 410 pp.

Copyright © Ted C. MacRae 2009

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An extendable handle for insect nets

For many years, my standard insect collecting gear has been a beating sheet and a short-handled aerial net (see small photo at right in “The Author” or the full-sized version under About). From the deciduous forests of the Ozark Highlands to the tropical bushveld of South Africa, these two pieces of equipment have been all that I’ve needed to collect the woodboring beetles that have dominated my interests. The beating sheet is, of course, an absolute necessity for anyone interested in jewel beetles (family Buprestidae), longhorned beetles (family Cerambycidae), and the many other insects that tend to be found on tree branches. Woodboring beetles are most frequently, but not exclusively, found on dead branches of their host trees, but regardless of whether the branches are alive or dead, the concept for collecting beetles off of them is the same – a beating sheet is held underneath the branch, and the branch is given a decisive whack with a stick of some kind. This dislodges any beetles that may be foraging or resting on the branch and causes them to drop onto the sheet, where they can be spotted easily and picked off before (hopefully) they escape. For my “stick” I like to use the handle of an aerial net, as the net itself is quite handy to have in case I stumble upon some of the many flower-feeding species or for more general collecting (my inability to focus exclusively on any one taxon is by now well documented). Using a net handle as a beating stick, unfortunately, forces one to compromise on the length of the handle – the handle must be relatively short (no more than 3′ long) to be effective as a beating stick, but such a short handle severely limits reach when the net is being used.  This problem has become even more apparent during the past few years as I have become increasingly interested in tiger beetles (family Cicindelidae).  There is no way around it – you need a long-handled net to have any hope of collecting tiger beetles, and the longer the better (ideally about 6′).  Thus my quandary – I needed a short-handled net to best collect woodboring beetles, but a long-handled net to best collect tiger beetles.

Enter the extendable handle for insect nets, available from BioQuip Products.  This ingenious net handle consists of two telescoping aluminum tubes with a clutch-lock device.  When fully collapsed the handle measures only 36″ in length – perfect for use as a beating stick and when extra length is not needed.  When a longer net handle is needed, however, a quick turn of the clutch-lock frees the inner section, allowing the handle to be extended to nearly 6′ in length – perfect for those fast-moving tiger beetles. Once extended, another quick twist of the clutch-lock secures the handle in place, and that Cicindela is mine!  To cap it all off, the handle is fully compatible with standard insect net rings and bags, including the red “T” knob for ring attachment. It was almost as if the handle had been designed specifically for my purposes.

I purchased mine at the beginning of the last field season. While the design seemed a perfect solution for my short handle-long handle quandary, I wasn’t convinced it would be able to withstand the rigors of field use. Specifically, I questioned whether the inner section would remain firmly seated within the outer section after a few slams of the net against the ground with the handle fully extended (for example, when using the ‘slap’ method for those tiger beetles I hadn’t yet figured out). I expected that repeated flexing of the handle would eventually cause the joint to fail and the handle to lose its rigidity. I also wondered how quickly and easily the handle would extend – especially after seeing some wear and tear. Any difficulty in this regard would quickly negate the convenience offered by an extendable handle.

I was immediately impressed with this handle upon its very first use, and after one full season of heavy use, it appears my concerns about its durability were unfounded. Weighing only 12 oz, it is extremely lightweight and easy to carry, and I am also pleased at how easily the handle extends and collapses – the clutch-lock disengages completely with a single twist, and the inner section slides into and out of the outer section smoothly and quickly. The true test of its durability, however, came during last year’s annual fall tiger beetle trip – a test that it passed with flying colors. I really put the net handle to hard use, and despite repeatedly slapping the net ring against the ground with the handle fully extended, the joint remained solid and rigid. I was able to swing the net with just as much assertion at the end of the trip as at the beginning.

Even during those times when I wasn’t carrying a beating sheet, I found myself routinely preferring to carry the extendable handled-net rather than the long-handled net. It was easier to carry and use when a short handle was sufficient, yet it could be extended quickly and easily when the extra length was needed. At $22.95, I consider its cost to be rather modest compared to the convenience and versatility it offers. For those of you who need a long-handled net but don’t want to wield a long handle all the time (and for the one or two other people in the world who use their net handle as a beating stick), this is the handle for you.

Copyright © Ted C. MacRae 2009

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Coral Pink Sand Dunes tiger beetle – range map

Those of you on RSS feed might be interested in revisiting my previous post, Coral Pink Sand Dunes tiger beetle on ARKive.  I’ve added a Google screen shot to the post that shows a visual perspective of the entire range of Cicindela albissima within a tiny inset of the state of Utah.  The image provides a sobering reminder of just how vanishingly small the range of this species is.  If we, as a society, cannot take the steps required to ensure the survival of a beautiful little species such as this one – living on only the tiniest sliver of the lands under our stewardship, it speaks ill of our ability to do so for other species with much greater habitat requirements.

Copyright © Ted C. MacRae 2009

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Coral Pink Sand Dunes tiger beetle on ARKive

I’ve been meaning to write about ARKive for awhile now. ARKive is a unique collection of videos, images and fact-files assembled from among the world’s very best wildlife videographers and photographers in an attempt to create a centralized digital library of life on Earth. Their short to mid-term priority is the completion of audio-visual profiles for the 16,300-plus species on The IUCN Red List of Threatened Species, before moving on to profiling all species that have ever been filmed or photographed. With backing from many of the world’s leading conservation organizations, ARKive hopes to “promote public understanding and appreciation of the world’s biodiversity and the need for its conservation, through the power of wildlife imagery.”

With tiger beetle season almost now upon us, it seems appropriate to highlight the media collection that ARKive has assembled for one of North America’s most spectacularly beautiful and critically imperiled tiger beetles, Cicindela albissima (Coral Pink Sand Dune tiger beetle). This amazing species is not only stunning in appearance, with its nearly pure white elytra, but has perhaps the most restricted habitat of any tiger beetle species in North America – the entire population being restricted to 400 hectares within coral-pink-sand-dunes_3Utah’s Coral Pink Sand Dunes State Park and the adjacent Bureau of Land Management (BLM) dune management area (Pearson et al. 2006). The Google screen shot at right shows the entire range of this species as a light pink swath (inset shown on larger map of the state of Utah).  Regarded initially as a subspecies of the widespread C. limbata (sandy tiger beetle), recent molecular studies showed this beetle to be only distantly related to that species and, thus, deserving of full species status (Morgan et al. 2000).

Unfortunately, the beetle’s highly restricted habitat continues to be adversely affected by ongoing, recreational off-road vehicle use, especially in the interdunal swales used by the larvae. Impacts occur not only by direct run-over mortality, but also through disruption of normal adult and larval activity, damage to vegetation, reduction of arthropod prey of C. albissima, and mixing of the upper soil layer which increases desiccation of the larval microhabitat (Knisley and Hill 2001). The species was nominated for federal protection under the Endangered Species Act in 1996 (when it was still considered a subspecies of C. limbata), and two years later a Conservation Agreement between BLM, U.S. Fish and Wildlife Service, Utah Department of Parks and Recreation and Kane County was established in an effort to protect the critically sensitive habitats in which this species lives. Despite these conservation measures, ongoing monitoring and research within the protected areas has documented a continuing decline in the population, suggesting that these areas may not be of sufficient size to enable the population to increase, and off-road vehicle use continues outside of the protected areas (U.S. Department of Interior, Fish and Wildlife Service (FWS) 2008). While still only a candidate for federal listing as an endangered or threatened species, the FWS now considers the magnitude of the threat from off-road vehicles, in view of these recent findings, to be high and imminent. As a result, the FWS has increased the priority of the species’ candidacy from 8 to 2 (1 being the highest priority a candidate species can receive).

While I would dearly have loved to embed one of ARKive’s extraordinary videos or photographs of C. albissima within this post, copyright considerations do not allow that.  What I can do is provide hyperlinks directly to the site, and I encourage everyone to visit ARKive and see their images of this gorgeous species.

Photos by Christine Breton: adult beetle, dorsal view, adult beetle, adults mating, habitat

Videos by Ganglion Films: overview, adults mating, adult burrowing in sand, OHVs threatening protected habit.

In addition to the ARKive images, Chris Wirth, author of the blog Cicindela, has taken photographs of this species and presents stunning examples of both the larva and the adult in his post Cicindela albissima (Re-post). I myself am making plans to visit Coral Pink Sand Dunes – perhaps this season – to find and photograph this species for myself. When I succeed, rest assured those photographs will appear on this site.

REFERENCES:

Knisley, C. B., and J. M. Hill. 2001. Biology and conservation of the Coral Pink Sand Dunes tiger beetle, Cicindela limbata albissima Rumpp. Unpublished report.

Morgan, M., C. B. Knisley and A. Vogler. 2000. New taxonomic status of the endangered tiger beetle Cicindela limbata albissima (Coleoptera: Cicindelidae): evidence from mtDNA. Annals of the Entomological Society of America 93(5):1108-1115.

Pearson, D. L., C. B. Knisley and C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp.

U.S. Department of Interior, Fish and Wildlife Service. 2008. 50 CFR Part 17. Endangered and threatened wildlife and plants; review of native species that are candidates for listing as endangered or threatened; annual notice of findings on resubmitted petitions; annual description of progress on listing actions; proposed rule. Federal Register 73(238) (December 10, 2008):75176-75244.

Copyright © Ted C. MacRae 2009

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Myths about why Lake Tahoe does not freeze

p1020598_2In my recent post, Born of glaciers, I touched on the formation of Lake Tahoe and discussed the glacial origins of Emerald Bay and nearby Fallen Leaf and Donner Lakes.  At the end of that post, I listed some interesting facts about Lake Tahoe, including the fact that Lake Tahoe does not freeze over.  That last fact was linked to one of the many internet sources explaining that Lake Tahoe’s massive size and the fact that its waters are always in motion prevent it from freezing. Sounded good to me.

Fortunately, my post drew the attention of David C. Antonucci, an environmental and civil engineer and author of the website TahoeFacts.com. David pointed out that this widely circulated explanation for why Lake Tahoe doesn’t freeze (repeated even by the U.S.D.A. Forest Service, Lake Tahoe Basin Management Unit FAQ website) is, in fact, wrong. David is currently updating his TahoeFacts.com website to include a more detailed explanation about this, but he sent me a draft of his update and has graciously given me permission to quote from it in order to help clear up some of the confusion.

As David points out, size is not the reason – Lake Baikal has more than three times the depth of Lake Tahoe and 160 times the volume, yet is freezes over to a thickness sufficient to support a railway. Nor is it the motion of the water – the Bering Sea is rocked all winter long by violent storms but still forms thick ice cover. The real reason results from a combination of three basic scientific principles:

  1. Freshwater has the unique property of reaching its maximum density at about 39°F – that is, water is densest at a temperature 7°F above the temperature at which it freezes.    For any lake to freeze, its surface waters must cool to 39°F, at which time they become denser than the underlying waters and sink beneath them.  This process continues until the water at all depths is a uniform 39°F, after which the surface waters can continue cooling down to 32°F and begin freezing.
  2. Freshwater bodies gain heat during summer when air temperatures exceed the temperature of the water at the surface and lose it during winter when air temperatures are below the water surface temperature.  The rate at which stored heat is lost during winter depends upon the surface area/volume ratio – lakes with a higher ratio (i.e., they have a large surface area compared to their volume) lose heat quickly, while those with a smaller ratio (small surface area compared to their volume) lose it more slowly.
  3. The rate at which heat is lost is also affected by climate.  Freshwater bodies in colder climates will lose heat more quickly than those with the same surface area and volume in a milder climate.

These three principles combine to explain why Lake Tahoe does not freeze over.  Lake Tahoe has a very small surface area/volume ratio due to its great depth but relatively small circumference.  This limits the rate at which stored heat is lost from the lake during the colder winter months.  The relatively mild climate that occurs in the Tahoe Basin, due to its proximity to the warm Pacific Ocean, further limits the rate at which stored heat is transferred to the air above it.  The result of all this is that the surface temperature of Lake Tahoe never reaches 39°F.  The lake is coldest in late March with a temperature of 41°F at the surface and gradually decreasing to 39°F at a depth of 500-600 ft and below.  Before the surface of the lake has a chance to cool further, increasing sunlight and air temperatures start raising the temperature at the surface.  By early May, surface temperatures reach 50°F, and they peak at 65°F to a depth of 15 ft by mid-August.  However, the summer warming penetrates only to a depth of about 375 ft – where the temperature has remained at 41°F.  Since the upper layers of water never cool below this temperature, they never sink below this depth and allow further cooling to take place.  It is, ironically, a lack of movement that prevents Lake Tahoe from freezing. In order for Lake Tahoe to freeze over, climatic conditions would have to become much colder, or the lake would have to fill in and decrease its depth enough to achieve a sufficiently high surface area/volume ratio.

David also points out that Emerald Bay has formed complete ice cover at least three times during the 20th Century and partial cover in more years. The reason for this is that Emerald Bay lacks the same depth of the main lake – its surface area/volume ratio is high enough to lose its accumulated heat and reach the required 39°F top to bottom during particularly cold winters.

Copyright © Ted C. MacRae 2009

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Trees of Lake Tahoe – The “Other” Conifers

The inviting openness of the Sierra woods is one of their most distinguishing characteristics. The trees of all the species stand more or less apart in groves, or in small, irregular groups, enabling one to find a way nearly everywhere, along sunny colonnades and through openings that have a smooth, parklike surface.–John Muir, The Mountains of California (1894)

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In a previous post (Trees of Lake Tahoe – The Pines), I discussed the six species of pine that can be found within the Tahoe Basin. These include Jeffrey pine (Pinus jeffreyi) – dominant around the lake at lower elevations, lodgepole pine (P. contorta ssp. murrayana) – common in meadows at lower elevations and replacing Jeffrey pine at higher elevations, ponderosa pine (P. ponderosa) – uncommon in the basin due to its preference for lower elevations, sugar pine (P. lambertiana) – the magnificent giant of high quality mesic sites along the western shore, western white pine (P. monticola) – co-occurring with lodgepole pine at higher elevations, and whitebark pine (P. albicaulis) – covering the highest peaks with its gnarled and twisted form.  In this post, I will cover the five “other” coniferous trees that can be found growing in the Tahoe Basin.  These other conifers belong to several different genera in two gymnospermous families – the Pinaceae and the Cuppressaceae.  Together with the pines, these trees comprise what John Muir described as one of the most diverse and appealing coniferous forests in the world. I am most inclined to agree with him.  The diversity of conifers found in the Tahoe Basin is reflective of the wide range of conditions occurring there as a result of differences in elevation (from 6,200 ft to more than 10,000 ft), exposure, and moisture.

Family-level identification of Tahoe Basin conifers is relatively straightforward – those with needle-shaped leaves belong to the Pinaceae (the pine family), while those with scale-like leaves belong to the Cuppressaceae (the cypress family).  There are other characters that distinguish members of these two families, but leaf shape is the most useful for purposes of field identification.  Nine of the eleven species of conifers found in the Tahoe Basin belong to the Pinaceae, while only two are members of the Cuppressaceae.  Within the families, the genera can be distinguished most readily by the following characters:

Pinaceae

  • Pines (Pinus) – needles linear, arranged in bundles or clusters of up to 5 needles held together at the base by sheath of papery bark (discussed in Trees of Lake Tahoe – The Pines).
  • Firs (Abies) – needles more or less flattened, growing directly and singly from the branch and with a plump base that leaves a round depression on the branch.  Cones upright, on upper branches.
  • Hemlocks (Tsuga) – needles more or less flattened and growing directly and singly from the branch like firs, but narrowly stalk-like at the base where they are joined to tiny wooden pegs.  Cones pendant, on outer branches.

Cuppressaceae

  • Incense-cedars (Calocedrus) – scale-like leaves 4-ranked, twigs branching in one plane to form flat sprays, cones > ½” in length, consisting of two large scales separated from a closed center.
  • Junipers (Juniperus) – scale-like leaves arranged in circles of 3, twigs not forming flat sprays, cones < ½” in length, berrylike.

There are three additional coniferous genera in the Sierra Nevada – each represented by a single species and found along the western slope – that do not occur in the Tahoe Basin.  These include: Douglas-fir (Pseudotsuga menziesii) – widespread at elevations from 2,500 ft to 6,000 ft (higher at the southern end of its range); giant sequoia (Sequoiadendron giganteum) – primarily in Giant Sequoia National Monument, and California nutmeg (Torreya californica) – of scattered occurrence.

White fir (Abies concolor)

As old age creeps on, the bark becomes rougher and grayer, the branches lose their exact regularity, many are snow-bent or broken off,…but throughout all the vicissitudes of its life on the mountains, come what may, the noble grandeur of the species is patent to every eye.

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White fir is second only to Jeffrey pine as the dominant conifer at the lower elevations within the Tahoe Basin¹.  It is immediately recognizable as the only non-pine member of the Pinaceae to occur at these elevations – red fir and mountain hemlock are found only at higher elevations in the basin.  Young trees have a nearly perfect pyramidal shape, with silvery gray bark that is thin, smooth, and p1020588_2covered with resin-filled blisters that can be “popped” to shoot out the resin. Older trees develop a more cylindrical and slightly irregular crown, and the bark becomes thick and roughly furrowed, changing to a dark gray or brown color. The foliage has a gray frosted appearance from below, and crushing the needles releases a delightful citrus smell that I found myself partaking in repeatedly. In the narrow elevational zone where white fir and red fir co-exist, white fir may be recognized by its more flattened needles (cannot be “rolled” in the fingers) which are distinctly twisted near the base, causing them to appear 2-ranked. White fir was seen throughout the Tahoe Basin at elevations below around 7,500 ft, and especially along the western shore and southern shores where the greater moisture and protection of north and east facing slopes are to this species liking.

¹ This post by Watching The World Wake Up provides an excellent introduction to the characteristics and distribution of white fir and its relatives. It also contains what must be the best tangent to ever appear in a botanical blog – the connection made between white fir and the alluring Salma Hayek (annoyingly mispelled “Selma” Hayek), softly singing Siente Mi Amor, is pure brilliance!

Despite its “noble grandeur,” white fir may be regarded as somewhat of a pest species. The suppression of fires that have been the hallmark of 20th century forest management have encouraged the replacement of pines throughout the Sierra Nevada by this species. White fir does not tolerate fire as well as the pines with which it occurs, but unlike those species it does well in shadier conditions. The suppression of fires has resulted in dense stands of white firs growing up in the spaces between the pines. Since it tends to retain its lower branches as it grows, when fires do occur the white firs can act as “fire ladders” that allow the fires to reach the upper canopies of the pines. Pines are not as shade tolerant as firs and are thus unlikely to become established beneath the dense canopy of firs. The result of these fire suppression policies are mixed-conifer forests that are denser and contain a much higher proportion of white fir than in the past, making the forests more vulnerable to stand-replacing fires as well as stress-induced insect and disease outbreaks. These counterproductive management policies are beginning to change – and I saw two controlled burns taking place during the week while I was in Lake Tahoe – but there is still much progress yet to be done if we are to once again see large expanses of the “inviting openness” that so captivated John Muir.

Red fir (Abies magnifica)

This is the most charmingly symmetrical of all the giants of the Sierra woods, far surpassing its companion species [white fir] in this respect… Happy the man with the freedom and the love to climb one of these superb trees in full flower and fruit.

p1020785_2I suspected I had seen this magnificent relative of the white fir in the higher elevations at Heavenly Ski Resort on my first trip back to the area last year, but lacking any real knowledge or field guides at the time it remained only a suspicion. When I returned to Heavenly this year, I was ready for it, and I recognized it instantly when I reached elevations around 8,000 ft. The massive trees with deeply reddish bark were unmistakable, and my only disappointment in seeing this species was that I was unable to approach them closely enough to allow a more thorough examination of their needles and bark. Like the white firs I saw at lower elevations, these massive trees had developed a bit of irregularity in their long, cylindrical crowns.

Younger trees can appear more similar to white fir because of their thin, smooth gray bark with elliptical resin blisters. However, in trees both young and old, the foliage is a more boldly colored blue-green than the paler foliage of white fir. p1020784_2Both species develop thick, deeply furrowed bark as they age, but the bark of red fir is distinctly reddish-brown or reddish purple, compared to the dark gray or brown bark of white fir – almost ashen in appearance. In the hand, the needles are not so flattened as white fir – almost quadrangular in cross-section and able to be rolled in the fingers – nor are they distinctly twisted near the base. The photo at right shows a stately red fir on the left next to a Jeffrey pine on the right at Lakeview Lodge on the California side of Heavenly (elevation 8,250 ft – the highest at which I saw the latter species).  I found this species growing in the company of western white pine (Pinus monticola), lodgepole pine (P. contorta ssp. murrayana), and mountain hemlock (Tsuga mertensiana), as well as in groves of its own kind (unfortunately, seen only from my perch upon a ski lift).

Mountain hemlock (Tsuga mertensiana)

The Hemlock Spruce is the most singularly beautiful of all the California coniferæ. So slender is its axis at the top, that it bends over and droops like the stalk of a nodding lily. The branches droop also, and divide into innumerable slender, waving sprays, which are arranged in a varied, eloquent harmony that is wholly indescribable.

p1020804_2I hadn’t a clue whether I would succeed in finding mountain hemlock – I knew it was a denizon of the snowy high mountains, though less common than some of the other high country conifers, and I didn’t recall noticing anything that might be this species during last year’s visit to the slopes of Heavenly. Of course, being a long-time resident of the Midwest I have little experience with hemlocks in general – eastern hemlock (T. canadensis) is on occasion planted in urban landscapes here, but mountain hemlock is markedly different from that species, as well as its Pacific counterpart western hemlock (T. heterophylla), due to its needles growing out of the twigs in all directions rather than in two flat planar sprays. Additionally, the needles are square in cross-section like spruce (Picea), a genus that does not now occur in the Sierra Nevada. These features caused 19th century botanists to suspect that mountain hemlock might have originated from an intergeneric hybridization event, as evidence by John Muir’s reference to it as “Hemlock Spruce.” However, no crosses between genera in the Pinaceae have ever been substantiated, and no compelling evidence of the presumed crossing events proposed for mountain hemlock has been brought forth (Lanner 1999).

p1020803_2Perhaps being primed by the readings I had done beforehand, I knew instantly I had found this species while riding a ski lift and seeing what looked at first like small junipers, but with a Tolkienesque appearance due to the gracefully nodding leader and drooping branch tips.  My hurried attempts to snap photographs of the trees from the moving ski lift produced nothing but skewed views marred by lift cables and passing cars, but once at the summit I was able to ski down to a little grove next to the ski run for closer inspection.  I immediately noticed the many cones clustered at the branch tips and was struck by their pine cone-like appearance. They were quite large – nearly 2” long (massive by hemlock standards).  Sadly, the only examples I would see of this species would be these small trees that only hinted at the charms of the massive specimens with trunks up to six feet in diameter that so enamoured John Muir.  Like the rare Washoe pine (Pinus washoensis) that occurs just outside Tahoe Basin on the eastern slopes of Mt. Rose, attempts to find some of these graceful 100-footers will have to await my next year’s visit.

Incense-cedar (Calocedrus decurrens)

Casting your eye over the general forest from some ridge-top, the color alone of its spiry summits is sufficient to identify it in any company.

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The incense-cedar is my favorite of all the Tahoe Basin conifers. The bright, cinnamon-red bark of mature trees, deeply-furrowed, fibrous and peeling, is reminiscent of California’s two most iconic conifers – redwood (Sequoia sempervirens) and giant sequoia (Sequoiadendron giganteum), respectively the world’s tallest and most massive trees. Incense-cedar is neither as tall as redwood nor as massive as giant sequoia – p1020590_2indeed, it is not even very closely related (redwood and giant sequoia belong to yet another coniferous family, the Taxodiaceae, containing also the graceful but much smaller resident of southeastern U.S. swamps, baldcypress – Taxodium distichum). Nevertheless, old trees – veterans of centuries of fires and storm damage – are stunning specimens to behold, their massive, buttressed trunks often draped in yellow-green mosses and bearing deep basal fire scars, their spired crowns often broken and forked.  Their flattened sprays of foliage give the tree a delicate, lacy appearance in beautiful contrast to its grizzled, gnarled bark. Indeed, even in death these trees stand out for their stark beauty.

Incense-cedar is common at lower elevations in the Tahoe Basin, especially down close to the lake and in the communities ringing the shore. It rarely forms “stands” like white fir and the pines, p1020670_2but rather most often occurs singly – as if to emphasize their distinctiveness. I found it most common along the western shore, where it grows scattered amongst white fir and Jeffrey, sugar, and ponderosa pines. Some of the most massive incense-cedars I have ever seen were found down near the lakeshore along the Rubicon Trail in Emerald Bay State Park. Common on these trees were what I take to be incense-cedar mistletoe (Phoradendron libocedri) (family Santalaceae), which is apparently rare in the Tahoe Basin but known to occur in the mesic forests of the west shore.

Incense-cedar is another of the so-called “wrongly named” conifers – it is not a true cedar (thus, the hyphen in the name), a group of conifers belonging to the genus Cedrus in the family Pinaceae that is found across Eurasia². While somewhat resembling the true cedars, incense-cedar’s closest relatives are restricted to China and Taiwan. p1020640_2Early botanist-explorers, when they first encountered this tree, named it for what it most resembled to them – the old world cedars. This distinctiveness makes older trees the easiest Tahoe Basin conifer to identify. Even it’s cones that litter the ground under mature trees are unique – slender, spindle-shaped, and about an inch long, with the two longest scales bending back at maturity in a manner resembling a wide-open duck’s bill with the tongue sticking out. Young trees resemble Sierra juniper by their scale-like leaves and peeling bark, but the flattened, yellow-green sprays of incense-cedar and shiny reddish coloration of the bark of twigs and younger branches are immediately distinctive.

² There are actually numerous examples of such wrongly named conifers – Douglas-fir (Pseudotsuga menziesii) is not a true fir; eastern redcedar (Juniperus virginiana), western redcedar (Thuja plicata) and Alaska-cedar (Chamaecyparis nootkatensis) are not true cedars; and baldcypress (Taxodium distichum) is not a true cypress. Long live scientific names!

Like white fir, the Sierra Nevada has seen a bit of a population explosion of incense-cedar due to the fire-suppressive forest management practices of the past century. Despite the thick, fire-resistant bark of older trees, the thin-barked seedlings and saplings are intolerant of fire and grow more slowly than the fire-adapted pines. As a result, the frequent low-intensity fires of the past kept seedling establishment to a minimum, resulting in spot occurrences of mature, fire-resistant specimens. The suppression of these fires, combined with the ability of incense-cedar to germinate in shade and thick layers of duff, have allowed this species to increase in incidence throughout the Sierra Nevada. Along with white fir, it is gradually replacing the pines. This may seem like a good thing from the perspective of foresters and loggers, who value the wood of incense-cedar for its use in making pencils and cedar chests, but from an ecological perspective this has the same negative consequences discussed above for white fir.

Sierra juniper (Juniperus occidentalis ssp. australis)

Its fine color and odd picturesqueness always catch an artist’s eye, but to me the Juniper seems a singularly dull and taciturn tree, never speaking to one’s heart.

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This was another conifer that I didn’t recall seeing on my previous visits, but from what I had read I really hoped I did. Gnarly and burly, mature specimens have a weather-beaten, picturesque quality that is unmatched by any other Tahoe Basin conifer save whitebark pine (P. albicaulis). While I did not find this tree to be common in the Tahoe Basin, I did find it in the most surprising of places – Emerald Bay overlook, where I had gazed in admiration at Lake Tahoe on so many previous occassions. This enduring dweller of exposed granite crags grows where no other trees can, anchored to crevices with only the tracest amounts of soil, p1020613_2seemingly thriving on nothing more than rock, snow, and sunshine. Old trees, with their massively short trunks supporting wind-pruned crowns, cannot be mistaken for any other Tahoe Basin conifer. The wood, it seems, is almost as hard as the granite upon which the trees grow, accounting for John Muir’s impression of this tree as without expression – not even the strongest Sierra winds evoke the slightest of shudders or the quietest of whispers in its unyielding bows.

I did not find this species commonly in the areas of the Tahoe Basin that I visited (which were mostly lower elevation sites below 7,000 ft). In addition to the specimens seen at Emerald Bay State Park, I also found this species near Upper Truckee River before the climb to Echo Summit, and I found a number of fine mature specimens outside of the basin proper at Pyramid Creek Geological Area.  Where I did find it, Jeffrey pine was the most common associate, but in most cases the trees stood alone in their own starkness.  Among the Tahoe Basin conifers, the small scale-like leaves are recognizable to almost any easterner as those of juniper, immediately placing it in the family Cuppressaceae alongside incense-cedar.  Even the young trees can be distinguished from that species by their non-glossy foliage borne on twigs that radiate out from the branches in all directions.  p1020602_21The bark of young trees is shreddy and peeling like that of incense-cedar, but it is dull brown to reddish-brown rather than the shiny purple-red color of incense-cedars.

Sierra Nevada populations of Juniperus occidentalis are considered a separate subspecies due to differences in reproduction and elevational preference.  Trees in nominotypical populations, found in northeastern California and up through eastern Oregon and Washington, are found at somewhat lower elevations (4,000 ft to 5,000 ft) and have cones of both sexes on the same tree; while those of subspecies australis, limited to higher elevations (usually from 6,500 ft to over 10,000 ft) in the Sierra Nevada, have either all male cones or all female cones.

REFERENCES:

Arno, S. F. 1973. Discovering Sierra Trees. Yosemite Association, Yosemite National Park, California, 89 pp.

Graf, M. 1999. Plants of the Tahoe Basin. Flowering Plants, Trees, and Ferns. A Photographic Guide. California Native Plant Society Press, Berkeley, 308 pp.

Muir, J. 1894. The Mountains of California. The Century Co., New York, xiii+381 pp.

Lanner, R. M. 1999. Conifers of California. Cachuma Press, Los Olivos, California, 274 pp.

Peterson, P. V., and P. V. Peterson, Jr. 1975. Native Trees of the Sierra Nevada. University of California Press, Berkeley, 147 pp.

Copyright © Ted C. MacRae 2009

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Winter botany quiz #4

Back to botany mode¹, and in that vein there are a couple of botanically-oriented carnivals with new issues just out.  The first is Berry Go Round #15 at Mary Farmer’s A Neotropical Savanna. An expert botanist herself, Mary presents a nice selection of March blog posts with themes ranging from spring (or not), tropics and the Southern Hemisphere, evolution and extinction, research, and food. The second is Festival of the Trees #34 at Seabrooke Leckie’s the Marvelous in Nature. A naturalist of many talents, Seabrooke has collected posts on trees from around the world and introduces them with her usual sagacity.  I have contributions in both of these carnivals, but of course, you’ve already read them!

¹ One caveat – it occurs to me that I needn’t be apologetic every time I switch to botany mode – the name of my blog is, after all, Beetles In The Bush 🙂

On to business – it’s quiz time again, and while much of the country moves into spring mode, winter hasn’t yet lost its snowy grip completely.  These pictures were taken in the waning days of winter, and I have my suspicions that somebody out there is going to ace this test considering the abundance of clues that have been dropped over the past week or so. In addition to the plant identities, bonus points to anyone who can identify a key commonality among them. As usual, comment moderation has been turned on for the next couple of days or so to give all an equal shot.

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Copyright © Ted C. MacRae 2009

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Tiger Beetle Safari

In looking back at my posts over the past few weeks, I realized that it has been far too long since I’ve actually talked about beetles.  Perhaps “Petals In The Bush” would be a better name for this blog!  I still have some botanical thoughts to get off my chest before the insect season starts in earnest, but until then, and in anticipation of the upcoming summer’s hunts, I offer this fun, light-hearted introduction to collecting and keeping tiger beetles by Peter Schriemer.  Pay particular attention to the method he uses to capture these elusive little creatures:

Tiger Beetles are my favorite type of beetle! Entomologist John Acorn got me hooked on these little guys. They live across the country in various habitats, so you may not need to travel far to go on a Tiger Beetle Safari of your own!

Vodpod videos no longer available.

more about “Tiger Beetle Safari“, posted with vodpod

Capturing tiger beetle adults can a little (lot) more difficult than implied by this video. Adults have excellent eyesight, and many species are extremely wary. It takes practice, patience, and lots of second chances. The collecting method shown in the video is what I refer to as the “stalk and slap” method – the beetle is slowly stalked until within net reach, and the net bag is slapped over the beetle.  This method works well enough, but it has its limitations.  If there are any gaps between the ground and the net rim, the beetle will quickly dart through them and fly away.  This is easy to prevent on sandy and soft clay substrates, as the net rim can be sealed against the ground by kneeling quickly on each side of the rim to embed it slightly and using the hands to hold up the net bag and locate the beetle.  Still, there are a few things I don’t like about this method – the beetle may hide against the inside of the rim and be difficult to locate, and once found it may be difficult to grab the beetle through the net if it is against the ground (don’t even try lifting the rim and reaching under – the beetle will zip out and be gone).  This method can also be taxing on the legs, as each attempted capture involves kneeling and standing back up (getting harder and harder for these 50+ year old knees to do).

The major limitation of the slap method, however, is that it doesn’t really work on hard, uneven surfaces. Many species are found in glades and other habitats with exposed rock substrates. In these types of habitats, the net rim simply cannot be clamped tightly enough to eliminate the gaps (not to mention the added difficulties in kneeling on these surfaces).  Because of this, I have adopted a technique that I call the “tap and swipe” method.  Here again, the beetle is stalked until within net reach (made easier with a longer handle), but rather than slapping the net bag over the beetle, the rim of the net is tapped against the ground next to the beetle and then assertively swiped sideways to catch the beetle just as it starts flying.  A quick 180° flip of the net rim closes the opening to prevent the beetle from escaping, and it is easily seen in the hanging net bag, where it can be grabbed from outside the net bag with one hand to secure it before reaching into the net bag with the other hand.  With a little practice, one eventually learns to reach down into the open net bag and grab the beetle while preventing it from flying up and out.  All of this can be done while standing, so it’s easier on the knees.

The tap method does require more knowledge about the beetle’s escape behavior in order to anticipate how quickly and in which direction the beetle will fly – some species delay take off just slightly, thus requiring a slight “pause” between the tap and the swipe. However, once their behavior is learned I have found this method to be more consistently successful than the slap method – even on soft substrates.  For species that I haven’t encountered in the field before, I use the slap method at first (if I can) until I have a feel for their escape behavior. If I can’t, I use the tap method and hope for the best!

Copyright © Ted C. MacRae 2009

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