Two Forms, Same Plant

What about fossil fuels is fossil? Some might say the "fossil" part comes from the fact that it is a rather outdated source of energy. Driving past the exhausted oil fields of Texas, it could certainly be said that it leaves fossils. Yet, as many of us know, they are fossil fuels because they are the organic, compressed remains of living things from ages past.

The Carboniferous Period. Image courtesy Mark Ryan.

Specifically, most of our fossil fuels come from the Carboniferous Period, which occurred between 359 million years ago (mya) and 299 mya. Appropriately name, "carboniferous" means "coal-bearing". It was a time when arthropods and amphibians dominated terrestrial ecosystems, and it was a time when giant ferns, mosses, scale trees, and ancient gymnosperms densely forested the land. Interestingly by the late Carboniferous the amniotic egg had arisen which opened the door for modern birds, reptiles, and mammals to evolve

Reconstructions of Lepidodendron (far left, Late Carboniferous, ~50 m tall), Sigillaria (left, Late Carboniferous, ~40 m,), Valmeyerodendron (middle top, Early Carboniferous, 0.6 m), Protolepidodendron (top right, Middle Devonian, 0.2 m), Chaloneria (bottom middle, Late Carboniferous, 2 m), Pleuromeia (bottom right, Triassic, 2 m) and Isoetes (bottom far right, extant, 30 cm). Courtesy of Devonian Times and Dennis Clark (c.)

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While all of those ancient animals and plants give us electricity, I want to focus on one group of species that are commonly found as the other types of fossils. Lepidodendron, also known as scale trees, grew over 100 feet tall and are most closely related to quillworts and club mosses. The largest fossil found was a plant ~6 feet in diameter. Despite its name, it was not what we would botanically consider a tree today. Considering its height, the plant did not contain much wood at all, and it was supported by an extremely thick, scale-like bark/skin. The scales of the giant tree herb provide for rather iconic fossils--just like the one I came across in the western Appalachian foothills of Ohio.

From what can be gathered from the fossil record, these trees were tightly packed wetland plants. Because of their growth pattern, 1000 to 2000 trees could squeeze into a single hectare. Imagine a giant trunk with a large clump of grass at the top, and you essentially have a Lepidodendron in mind. It wasn't until the plants reached a mature stage that they had branches. It is estimated that these plants reached maturity in 10 to 15 years and would disperse their spores from cone-like structures.

If you want to enjoy Lepidodendron as a fossil and a fossil fuel, you have the best chances of looking near shale rock.

Want to learn more? Take a look at
Stewart, W.N and G.W. Rothwell. 1993. Paleobotany and the Evolution of Plants. Cambrige: Cambrige Univ. Press.
Taylor, T.N and E.L. Taylor. 1993. The Biology and Evolution of Fossil Plants. New York: Prentice Hall.

A Tiny Salamander Appears

As winter draws near, it will be time for many terrestrial salamanders to reduce their surface activity and switch to their underground retreats. While some salamanders will use underground burrow networks created by small mammals, others will create their own.

Some members of the red-backed salamander species (Plethodon cinereus) will especially need to find a retreat soon. Starting in August, neonates hatched from eggs suspended in crevices inside logs, under rocks, and underground. These tiny salamanders are barely 25mm long. After an average of 6 weeks of gestation in eggs, the salamanders (depending on latitude) have only a few months before winter sets in. During this time, they disperse from the nest, forage, and find areas to overwinter.

Female P. cinereus typically lay their eggs (collectively called a clutch) in late spring and early summer; however, it isn't uncommon for females to oviposit later in the year. The number of eggs in the clutch ranges from 1-14 and is often correlated to the size of the female. Unlike males that mate each year, female P. cinereus reproduce biennially. Developing eggs, and eventually brooding them, is energetically expensive. Clutches that aren't brooded have a higher chance of being eaten, as the brooding female will lunge, bite, and snap at other salamander intruders. In some cases, conspecifics (members of the same species) will cannibalize eggs due to their energy content and nutrients.

Here in the Northeast, winter is quickly approaching, so lets hope this year's neonates are able to find retreats deep enough that they don't freeze.

References
Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington, DC. 576 pp. 

Volen't You Leave My Plants Alone

Voles. While there are 32 species found in North America, there are two primary species in the east that are commonly found in grasslands, woodlands, and your garden. This includes the meadow vole (Microtus pennsylvanicus) and the woodland vole (Microtus pinetorum). While these two relatives occupy different habitats, they play a vital role in ecosystems, and they can have serious effects on habitats when they reach high densities.

The meadow vole is generally larger, reaching almost up to 8 inches. Voles can be distinguished from other rodents by their noticeably short tails. As long as there is dense vegetation at the ground level, meadow voles can be found in most grass dominated habitats north of South Carolina--marshes, fields, meadows, orchards. Interestingly, meadow voles create elaborate tunnel systems in the vegetation called runways. The meadow vole can burrow, but its runways are its hallmark. Along these runways they forage for herbaceous material, seeds, insects, and fungi. Meadow voles exhibit very unstable populations. They can be very abundant one year but barely detectable the next.

I believe a friend of mine put it best: "Meadow voles are like giant ground sloths, man."

Of the rodent world, of course.

Its conifer-named cousin, the woodland vole is a different creature by nature. Unlike the appropriate name of its cousin, the woodland vole, also called the "pine vole" (pinetorum afterall), is rarely found in pine dominated forests.  For the woodland vole, underground tunnels and burrows are the main mode of transportation and food storage. Woodland voles are much more cryptic, as they spend the majority of their time underground. Oftentimes, woodland voles can be found in colonies, but the reasons for formation and disintegration are little understood.

A smaller creature in stature, this species has larger forepaws adapted for digging. 

Both of these species are staple foods for many predators: foxes, coyotes, raptors, and snakes. In some areas, they may be the dominant small mammal and therefore play a significant role in ecosystem energetics. However, these species are probably most notorious for their multi-million dollar destruction of orchards, farm fields, and nurseries. Particularly during the winter, diets in both species shift to bark and root consumption. Sometimes this can lead to the girdling of trees. Gardeners also loath the vole, for their shallow tunnels are often seen leading to dead plants or consumed vegetables. Moles are often blamed for the damage, but moles are carnivorous. 

Even though the meadow vole and woodland vole are important species in their natural habitats, they provide a good example of how wildlife can cause conflict when natural habitats and human habitats meet.

Sources

National Audubon Society. Field Guide to North American Mammals. Alfred A. Knopf: New York, New York.

Webster, WM. D., J.F. Parnell, and W.C. Biggs, Jr. Mammals of the Carolinas, Virginia, and Maryland. The University of North Carolina Press: Chapel Hill, NC.

Red vs. Blue

It's been a while since I've posted true to my namesake, and considering my past field job revolved around salamanders, it is high time to share some salamander knowledge.

While conducting salamander surveys in the foothills of the Appalachian Mountains, a certain pattern arose between two salamander species studied at a contiguous forest. The first species, Plethodon cinereus (Red-back Salamander, Plethodon Greek for "Full of Teeth", and cinereus Latin for "Ash colored") is one of the most thoroughly studied salamanders in North America. They are prominent throughout much of the eastern and northern United States.

The second species is Plethodon electromorphus (Northern Ravine Salamander, named after the process of electrophoresis that was used to determine it as a different species from P. richmondi). This species has not received as much research attention, but the Plethodon genus of salamanders are often hard to study due to their cryptic nature and subterranean habits. During the summer and winter, P. electromorphus can be as deep as 1.2 meters below ground.

After many weeks of surveys, it became clear that the two species were not occurring in the same local habitat at all, despite having noteworthy numbers of captures at survey sites within a mile of each other. There could be several different explanations for this pattern. For instance, P. electromorhpus prefers rocky outcroppings or rocky slopes within forests. P. cinereus is most abundant in mature forests with well-drained soils and plenty of woody debris.

Although it hasn't been noted in the literature between these two species, it is possible that they exhibit strong interspecific competition. In diet, foraging behavior, and morphology, the two species are very similar. They consume invertebrates of several orders, forage at night, and require moisture along with cooler temperatures to be active on the surface. Their activity schedules are mostly tied to their mode of respiration and consequent physiological requirements. Could it be possible that these two salamanders are an example of the competitive exclusion principle? Or, are P. eletromorphus only locally abundant?

A juvenile P. eletromorphus. It weighed 0.6 grams and was less than 11 mm total length.

Considering the habitats in which these traps were located--well-drained soils, rocky slopes, woody debris, moist leaf litter, mixed deciduous hardwood forest--there is no reason both species could not be present. The traps where P. cinereus were found was drier and had less ground cover, so it would not be a moisture problem. Even if the Ravine salamanders were only locally abundant, there are no noticeable/obvious habitat characteristics or environmental factors that would hinder Red-back salamanders from occupying the same area as them. Given the fact that P. cinereus are also more aggressive and territorial than P. electromorphus, it should be the former imposing on the latter and not the other way around. All in all, it was an interesting trend to see emerge over the course of the surveys, but I cannot make any assertions one way or another.

References
Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington, DC. 576 pp. 

Flowers Flowers Everywhere

As part of my current job in the Midwest, I have gotten to hike the same 6 or so miles everyday since mid-March. This has been a great way to see how a whole forest landscape changes with the seasons. Because of the varied topography, geology, and forest types present, I have gotten to see a quite a variety of wildflowers as they come into bloom. Below are some of my favorites, enjoy! 

    

Woodland Phlox (Phlox divaricata divaricata)

A nectar source for butterflies and hummingbirds.

Fire Pink (Silene virginica)

Pollinated primarily by the Ruby-throated Hummingbird (Archilochus colubris)

Dutchman's Breeches (Dicentra cucullaria)

Seeds spread via myrmecochory--ants are specifically attracted by seeds and seeds are taken to the nest--providing both a food source for the ants and a rich soil for germination.

Jack-in-the-Pulpit (Arisaema triphyllum)

Contains oxalic acid which is poisonous. Used medicinally for sore eyes, rheumatism, and snakebites.

Showy Orchis (Galearis spectabilis)

Often called a hooded orchis due to the fact that the petals and flower are found

inside the purple and white sepals.

Bellwort/Merry Bells (Uvularia perfoliata)

Perfiolate, which means the leaves grow around the stem, a unique growth pattern.

Blue-eyed Mary (Collinsia verna)

One of the few wildflowers that exhibit a true blue color.

Yellow Lady's Slipper (Cypripedium parviflorum)

This orchid is threatened or endangered in many states.

White Trillium (Trillium grandiflorum)

A contester of Reid's Paradox, which states that plants could not have survived past glaciation if their seed dispersal is less than several hundred meters per year. Once again a flower that uses myrmecochory.

Have you found any favorite flowers in bloom yet? Depending on your latitude, there are still many flowers that have yet to bloom, so get outside and check it out. 

Twitterpated

Well, it's getting that time of year where all the animals are getting frisky. Many of the amphibians are waiting for their larvae to hatch, and some are in the race against time to metamorph for terrestrial life before their breeding pools dry up.

Now that it is getting warm enough for the reptiles to stir, their season of reptile love (and war) is starting to begin. In particular, I came upon a male Northern Fence Lizard (Sceloporus undulatus) trying to woo a female in courtship. Typically, fence lizards do push-ups to mark their territory and to signal that other lizards should stay away; however, in this case, there is a male and a female fence lizard present, so I am guessing it has more to do with that than anything else. For the fence lizards, mating season typically begins in April. On top of their macho push-up routine, males will also use a pheromone to attract a mate.

Maybe it is because I interrupted the process, but I don't think the female showed much interest. (For both videos, play in higher resolution).

Please forgive the disenchanting narration. My coworker called to tell me he

had found a snake.

In part to attract a female, but also to show how tough they are, males also have a bright blue coloration on their belly and neck. Thus, when the lizard conducts their push-up routine, the colors are flashed as the lizard goes up and down. One way to tell the difference between a male and female is that the blue color is much less intense on a female, and it often is less apparent on the neck. Below is the male, and from this angle you can see the blue much more vividly (The blue doesn't show up unless it is played on the higher resolution youtube setting).

If the mating is successful, the female will be in gestation for about eight weeks, after which she will lay the eggs under a few inches of soil. This will help regulate the temperature of the eggs. Depending on when the eggs are laid, they will hatch between June and September. The size of the female determines how many eggs are laid, and it ranges from 3-13 eggs per clutch. During the year, a mature female can have multiple clutches. Younger females (1 year-old), typically only have one clutch per year.

As these are a very common species, I'm sure you all have been seeing them moving about now that spring is here.

References

Adolph, S., W. Porter. 1996. Growth, Seasonality, and Lizard Life Histories: Age and Size at Maturity. Oikos, 77: 267-278.

Ferguson, G., C. Bohlen, P. Woolley. 1980. Sceloporus Undulatus: Comparative Life History and Regulation of a Kansas Population. Ecology, 61: 313-322.

Presidents and Fellows of Harvard College. 1983. Lizard Ecology. Cambridge, Massachusetts: Harvard University Press.

Odin to a Bobcat

He gave the orb of an eye to Mimir's Well,

and in return sound counsel bequeathed.

            My own eye watched,

            wrought of glass and wire,

Upon the bark of Yggdrasil it waited in steel sheathed.

On the path through the wood this avatar did tread.

The wanderer, Asgardian, the Allfather

            filled Midgard with dread,

yet this forest deity I did bother,

and now too I must search for an answer.

           

            Thank you for indulging my amateur attempt at the ode form of poetry. Also, please excuse the terrible pun titling this post.

            So you are probably asking, what is all the theatrics for? Well, at my new temporary playground in the Midwest, I have gotten an interesting set of pictures on my camera trap. Not too long ago, a one-eyed bobcat (Lynx rufus) made his way by my camera trap, and considering my the gadget had only been up two weeks, I was pretty ecstatic to see it! In my past experience, such camera-trap captures are infrequent to say the least.

            Bobcats are nothing new in North America. The oldest fossil they have of a bobcat ancestor is from 2.4-2.5 million years ago (Anderson & Lovallo, 2003). Even though the current distribution of the bobcat spans from coast to coast and from Canada down to Mexico, they have restricted ranges in certain states.

            Now I am not sure if the Odin bobcat I got a picture of is big or small, young or old. My guess is he is a male, though, and that arises from the fact it is breeding season, and females move significantly less than males (see Anderson & Lovallo, 2003). Either Odin has seen some battles and has successfully protected his territory from other cats, or he is down on his luck and has been fended off by some bigger males.

            It is also quite possible that I got pictures of two different cats. The photograph from the 24^th looks a little more husky and large, yet when they are both nearest to the stem in the center they are around the same height. The individual from the 31^st seems to have more spots on his legs. It's plausible that they are two different individuals. In terms of movement, adult bobcats can move over 2 km in a day (with a home range around 40 km^2 depending on region; see Anderson & Lovallo, 2003). When it comes to younger cats dispersing, it is not too uncommon for individuals to move more than a couple hundred kilometers in search of adequate habitat.

            Either way, it is a neat series of pictures. I would be interested to hear your thoughts.

Works Cited

            Anderson, E.M. & M.J. Lovallo. 'Bobcat and Lynx'. In Wild Mammals of North America: Biology, Management, and Conservation. Edited by G.A. Feldhamer, B.C. Thompson, and J.A. Chapman. John Hopkins University Press, Baltimore, MD: pp 758-788.

Torpor Affects Us All

Despite the unusually warm winter (2012 being the hottest year on record for the continental U.S.), even I succumbed to winter torpor. Good thing I stocked up some energy with all of the holiday treats!

Diverging from our small-mammal accounts from my time on the Eastern Shore of Virginia, I wanted to provide a quick glimpse at some of the herpetofauna I found while island hopping. It is surprising to think how these animals made it to the islands via saltwater (predators and dehydration) and how they have been able to survey on dynamic ecosystems that are constantly flooding and changing habitat types.

This Eastern Box turtle (Terrapene carolina carolina) was found on Smith Island, which is one of the southernmost barrier islands off of the Delmarva Peninsula. At it's closest point, the island is approximately 2.2 km from the mainland. That is a long way for a terrestrial turtle to go in a harsh environment. Given the number of storms that occur though, it is possible it got blown or swept there. Conant et al (1990) also hypothesized that the turtles might have been brought to the island when it was inhabited by humans up until the 1930s. It seems the population has been able to survive in the wooded areas.

I also came across a rather feisty Black Rat snake (Elaphe obsoleta now Pantherophis obsoletus) while on Mockhorn Island. Mockhorn and Smith occur close together, and the snakes have been documented on Smith Island in the past. Interestingly, this individual was sunbathing on a rather cold and cloudy day. Perhaps it had planned poorly, for it was stranded on a small tump of high ground during high tide. For an instant I expected it to ask for a Marsh Rice rat from one of the Sherman live-traps.

While doing surveys on the mainland, I was also able to glimpse this speedy Ground skink (Scincella lateralis)  "dancing" through the pine needles. These skinks are unusual in that they rarely climb, and they wriggle their body back and forth to move. They can grow up to five inches, so the one in my hand is not all that large.

Switching gears to our amphibian friends, I came across two frog species while working around the field station. The first (above) is a Green Tree frog (Hyla cinerea). The second (below) is a Southern Leopard frog (Lithobates sphenocephalus). The fun thing about the Green Tree frog was that I watched it turn from a bright green to the olive green you see in the picture. This may have been due to an effort to camouflage or because it moved from the sun to the shade. The Southern Leopard frog is simply a nice looking creature.

Sources
Conant, R., J.C. Mitchell, and C.A. Pague. Herpetofauna of the Virginia Barrier Islands. Virginia Journal of Science 41: 364-280.