Wednesday, April 22, 2015

After the fires in New Mexico

Valles Caldera Grande, Jemez Mountains, NM
I've been traveling a lot for work lately, and last week I was in Santa Fe NM. I was there to attend a conference on native seeds. The day before the presentations started I was able to attend a field trip touring recovering wildfire sites in the Jemez Mountains, near Bandelier National Monument. Most of the sites we visited had burned twice, once in 2008 (I think), and again in 2011.

wild candytuft (?) in the caldera
We visited the Valles Grande in the Valles Caldera, an active volcano complex 13.7 miles across altogether. This caldera last erupted approximately 1 million years ago. We were given half an hour to explore it, and most of us made a bee-line to the meandering creek dividing the center of the caldera. The problem is it appears deceptively close. I'd guess the Valles Grande is ~3 miles across where we parked. Not one of us made it to the creek by the halfway point, and we were called back short of our goal. Oh well. At least we got to tromp around this montane clearing.

What I didn't understand is this: why no trees? Ponderosa pine and aspen grew at elevations both above and below the caldera, so why not in the caldera itself? Is the ground too saturated with water? The caldera supported a luxurious grass thatch, even with the recent wildfires and historic grazing. Candytuft and marsh marigold (questionable IDs) were the only non-grass plants active at this point in the season.

We could see an abundance of human activity despite the remoteness of the location. The Valles Grande has a (now defunct) ranch within it, and shards of flaked obsidian near the overlooks marked the points where native peoples had sat and worked the stone long ago. The presence of the obsidian shards on the soil surface is a testament to the relative remoteness of the locations we toured. Surely more travelled trails would have had these remains pocketed years ago. It is also possible that the tremendous fires of the past ten years have exposed these remains at the surface.

Unmolested flint knappings at the soil surface
I know that in the tropical rain forests, the first fire marks the beginning of disturbance, but it is the second fire that destroys the ecosystem. This area suffered the same fate. Trees that survived the earlier fire were killed 5 years later when the second fire came through and burned the underbrush and deadwood. Apparently, the smokejumper team from Prescott Arizona that perished in 2013's Yarnell Hill Fire cut their teeth on the 2011 fires in the Jemez.

Compare the brown areas to the green
With this is mind, it was easy to lose myself re-enacting fire behavior in the mountains from the fire scars and standing trees. At its peak it advanced an acre a second. You could see where some (very few) pines had been spared, but you could also see white scars on the earth where the fire had burned so hot the soil had been mineralized, still visible 4 years later. Would my instincts have led me into a trap? I'll never know.

Mineralized soil and dead trees, 4 yrs later

Saturday, April 11, 2015

The monarchs have returned to Texas

Monarch butterfly, probably male
Actually, they returned over a week ago. I believe I saw my first monarch of the year April 1st. It was a female, hopping from milkweed to milkweed. She deposited one egg on each plant. One of her cousins was doing the same nearby. I was impressed with how she homed in on each plant, wasting no time in the search.

side-cluster milkweed w/egg
 Monarch butterflies are incredibly widely distributed, and are found in all lower 48 states.  They even introduced themselves to Hawaii. The Hawaii population is especially unusual because they have developed a unique white morph in contrast to the bright orange we see on the mainland. However, the two major populations are found in the lower 48 states. They can be further split into the western population (approximately 5% of total), and the eastern population (most of the remainder). The eastern population is the subject of the listing petition, and it is the group we see in Texas. This group has seen a 90% decline in overwintering numbers in the past 20 years. While monarchs as a species are secure, this eastern migration is an endangered biological phenomena.

Monarchs have a peculiar life history.  The first 3-4 generations of the year live approximately 4 weeks and grow and reproduce like a standard butterfly. They follow the fresh milkweed and flowers north as the season progresses. However, the last butterflies of the year to hatch live 6-9 months and migrate thousands of miles south from the Upper Midwest to Mexico. These butterflies are in reproductive diapause- that is, they don’t breed- and they focus their energy on gliding south in September, October, and November.  Once they hit Texas (generally in October), their migration slows. Instead they feed, intent on gathering enough fuel to support themselves during the 6 months they spend overwintering in the oyamel fir forests in the mountain highlands west of Mexico City.

Monarch ovipositing on milkweed
The monarchs arrive at their overwintering grounds in Mexico around the first of November most years. Their arrival coincides with the Day of the Dead celebrations, and monarchs are taken to represent the visiting souls of departed loved ones. Once the monarchs arrive, they become dormant and roost in high density “shingles” entirely coating the trees in their chosen forests. They don’t feed or breed, and spend most of their time resting on the branches and trunks of these oyamel firs. It is at this time that the monarchs are counted. Because the monarchs roost socially in high numbers, you can get a population estimate based on the area occupied. The lowest ever numbers were recorded in the winter of 2013, when the entire eastern population, ~95% of the world’s population, only occupied 1.7 acres.

Fresh monarch egg
By mid-March, spring returns to the Mexican highlands and monarchs break dormancy. They mate and begin their migration north. Monarchs return to south Texas in late March, making the thousand mile trek from Mexico in about a week. Once they reach Texas, they search out fresh milkweed sprouts on which to lay their eggs.  It was these tired, 9 mo old females I observed ovipositing earlier this month. After breeding, this generation dies. It is their offspring which continue the journey north to recolonize their North American range. Each subsequent generation moves a little farther north, until September when the “methuselah” generation hatches and the cycle begins again.

2nd instar monarch caterpillar
Texas is crucial to the monarch habitat for two periods of the year- those first monarchs returning to the states, and the last generation to leave. In March and April, the returning females nectar on wildflowers and lay their eggs on milkweed, the only food plant which can support their caterpillars. Texas becomes important again in September and October, when migrating monarchs stop to re-fuel on wildflower nectar before their long slumber in Mexico. Without nectar in the fall, these monarchs will not survive the winter. Without milkweeds in the spring, their offspring will starve. We can support monarchs as they funnel through our state by planting milkweed and fall blooming nectar plants. We cannot control what happens to these butterflies across the entirety of their range, but by working in our own backyards we can support the start and end of their migration.

Photo credits: Figures 2 & 4: Philip Barbour, CNTSC; Figure 1 & 3: Anne Stine; Figure 5: Rosanna Brown, CNTSC.

Tuesday, April 7, 2015

Fighting slime with slime

Or: the tale of two gastropods, slime and punishment, etc etc...
A curious brown garden snail
I've often noticed large round snails clinging to plant stems in the shade or on wet mornings. They seem to be everywhere. Known as the the brown garden snail, these beefy vegetarians are native to the mediterranean. They were originally imported to North America to serve as escargot. Edible, though perhaps not palatable to American tastes, these snails now range across most of the southeast and California.

These introduced snails are a minor garden nuisance, but high populations in California have vexed the citrus industry. The best snail management plan has a multi-pronged approach. Removal of daytime hide-outs, snail baits and traps, using copper barriers, and releasing another non-native mollusk: the decollate snail [1, 2] are used in tandem to knock back populations. Unlike the brown garden snail, the decollate snail is a predator. It hunts other snails.

Releasing one non-native to control another is called "classic" biological control, and has a storied history. In Australia the cane toad was introduced to control a pest beetle, but has since become a much larger threat to ecological stability than the beetle ever was. Closer to home, in North America a parasitic fly introduced to control gypsy moths has directly contributed to the scarcity of our own beautiful silk moths. The luna, the cecropia, the polyphemus, and the promethea are all much rarer than they once were. A little bit of magic left our eastern forests. On the other hand, biological control is our last best hope in the case of the hemlock woolly adelgid and purple loosestrife , so it cannot be discounted completely.

While the UCANR Integrated Pest Management (IPM) guide noted that releases of the carnivorous decollate snail are prohibited outside certain areas (because the decollate snail is a generalist, and will eat native snail eggs as readily as those of a pest), I have not heard of the decollate snail causing problems. Of course, how would we know. I can count the number of individuals I know who can even identify snails on one hand, let alone track and monitor native population dynamics.

But, what's done is done. When I turn the soil in my garden bed, the shells of both non-native snails surface in abundance. Eradicating either species is likely an exercise in futility at this point. However, their history piques my interest in our native snails! I'll have to keep a look out for these tough survivors.

Foreground: decollate snail shell. Background: brown garden snail shells

Tuesday, March 31, 2015

Early spring wildflowers part 1: Marion Sansom

Yucca and mexican buckeye on a limestone slope
Fredericksburg Division limestone
exposed, north end below dam
Most of Texas is afflicted with spring fever lately, its sweetness tempered by urgency because we know it cannot last. Any moment inside feels like a prison sentence. It is with this sentiment that I set about exploring Marion Sansom Park last weekend.

Marion Sansom Park is owned by the city of Fort Worth but has been adopted by the Fort Worth Mountain Bikers Association (FWMBA). These cyclists build and maintain the trails and signage. They are an enthusiastic presence on the trail, but I tend to move at a much slower pace. Especially when there's so much new stuff to see. The park itself borders the Lake Worth Dam, interesting because it looms near a limestone exposure in the Fredericksburg Division [1].

Lake Worth Dam, north side.
honey bee, mexican buckeye
The park is situated near the juncture of the western cross timbers and the grand prairie. This site, underlain by shallow limestone on a south-facing hillside, has a somewhat peculiar flora.
honey bee, redbud

I was most surprised to see mexican buckeye in abundance, which I had thought to be a more southern species. Mexican buckeye has pretty pink flowers and unique, pendulous tri-lobed fruits. The seeds, once released from their capsules, resemble rich brown marbles. I also saw blooming new jersey tea, redbud, plum, ten-petal anemone, prairie verbena, prairie parsley,  fringed puccoon, and coral honeysuckle.  The coral honeysuckle has emerged just in time for our returning hummingbirds, and it is one of their preferred nectar flowers.

A few coral honeysuckle flowers are already open
Mexican buckeye fruits
More butterflies are out too. Checkerspots, southern dogfaces, and swallowtails are now fanning about in addition to the familiar sulphurs and commas. I am almost certain I caught a glimpse of an early monarch gliding over my back garden.

The vertebrates were also out enjoying the weather. A coy green snake stuck his head out of a hollow tree to watch me walk down the trail, but retreated when I turned to take his picture. I had to wonder: how did he raise and lower himself so easily within his tree trunk? Is he braced against the walls, or does he have an interior shelf on which to rest?

It already felt warm on this southern exposure in the sunshine, and I was glad to wander the slopes of Marion Sansom in early spring. Last year we came close to 100 F by late April, and we are already projected to break into the 90s this week. Spring in Texas, like much of the rest of the world, is fleeting. I intend to get out in it as much as I can.

Cute green snake, peeping out of his front door.


Sunday, March 22, 2015

The emerald city stinks

Oil and gas refinery? Or something else?
I've been thinking a lot about the future, in particular about how the world in which I retire will be different from the one I now inhabit. I'm at the point in my life where I'm seriously thinking about where I'll 'make my stand', buy a house, plant fruit trees... It's hard to plan for such things when you are very much aware that the world is changing, and you can't count on the place you settle staying the same over the coming decades. How do you put down roots when the Earth itself is shifting beneath your feet?

You may remember that I went to southeastern New Mexico over my winter vacation. High Country News recently published an article on oil and gas extraction titled "Lessons from boom and bust in New Mexico," which brought that trip back to mind. There, oil and gas exploitation dominates the landscape. There is no urban clutter to distract from the pump jacks and gas flares.  The night sky is orange from the natural gas burned off, relieving pressure on extraction equipment. The air stinks like cancer, and you drive past warning signs saying: "Danger: Toxic Fumes when lights flashing".

It's all your fault, car (not really).
Obviously, I was not so taken with the local industry as I was with the scenery. Oil and gas exploitation is one of those trades that is inherently extractive. Its nasty byproducts, and its contributions to our changing climate, make it an easy scapegoat. However, when communities have nothing else, how can you tell them not to mine the money stored in their shale piggy bank? Don't their kids deserve college as much as ours?

Additionally, one could argue that fossil fuels built Texas. Without oil, we'd be just another south central Ag state. Our economy might be more similar to that of Oklahoma. The Texas GDP, at $1.6 trillion, is second only to California in the United States. Our state's GDP is higher than that of Australia. This quick money does come at a public cost. Policy wonks call these "externalities." These costs are borne by those other than the organization which incurred them; and they include the poor air quality and increases in atmospheric carbon dioxide.

Climate Central's summer and winter projections for Fort Worth, year 2100
In a series of projections put out by, Fort Worth doesn't look quite uninhabitable by year 2100, but it's certainly less pleasant. Believe it or not, as hot as our summers get, the average temperature is only ~94F. We'll be adding ten degrees to that by the end of the century. This addition brings our temperatures to those of the Phoenix metro area, averaging 103F  (including nightly lows!). Indeed, our winters will warm too. Instead of 31 nights below freezing on average, we are likely to have only 8. I am tempted to console myself with "Well, at least I'll be able to grow avocados outdoors", but it isn't that simple. Changing global temperature averages shift the prevailing winds too. This changes precipitation regimes.

Projected precipitation changes (%) by year 2100
The map of projected precipitation shifts posted on the EPA's climate science hub suggests Texas will be drier, especially in the summers. Less rain + increased evapotranspiration (water lost to the atmosphere from plant exhalations and soil surface evaporation) is likely to shift our ecotype from Cross Timbers/Blackland Prairie into something much more arid. From our temperature projections, we could very well resemble the Sonoran desert. So: should we all plant saguaros and be done with it? While I'm tempted to move into an adobe with a cleverly crafted cistern system, there's still some hope. We could shift to renewable energy. Or perhaps we could hold industry accountable for its "externalities".

In a more basic, blind luck sense, precipitation changes are much harder to predict than temperature. While the scientific consensus is that the Earth will warm, the atmospheric eddies that determine rainfall are harder to model. You may notice that coastal areas are projected to increase in temperature more slowly than regions in the middle of the continent. This effect is due to buffering from the oceans. Water absorbs heat when it evaporates. Perhaps, if the air-stream shifts just so, we'll get enough moisture to prevent the "Arizonification" of Texas. Perhaps.

Don't be sad. Look at the pretty gypsum dunes!

Tuesday, March 17, 2015

Early spring at Copper Breaks

View from the edge of Bull Canyon, Copper Breaks State Park
Last weekend I took advantage of the warm weather and drove the 3 hours northwest to Copper Breaks State Park, 12 miles south of Quanah, Texas. Red dirt from the Permian has been cut and dissected into closed canyons and mesas. Thick cedars and brush on the interior of the canyon limit your line of sight. You feel so vulnerable to ambush. Of course, that could be me projecting my knowledge of the past onto the present. This canyon is within the Comanche heartland. Cynthia Ann Parker, one of the subjects of the popular book on Comanche history "Empire of the Summer Moon" was recaptured close to the park. Today the park is popular with families and youth groups. I wasn't the only one camping out last weekend.

Inside the canyon
The landscape is treed with juniper and mesquite. Mid-grasses grow well on the uplands, and they are dotted with cacti. Mormon tea (Ephedra antisyphilitica), pencil cactus (Cylindropuntia leptocaulis), and agarita (Mahonia trifolialata) are all more common here than further east. As you might guess from the latin name, mormon tea was once used as a treatment for syphilis. So many native plants have the species epithet "antisyphilitica" or "siphilitica", it makes me wonder about the prevalence of syphilis in North America pre-penicillin. I can think of three native plants off-hand that were used to treat syphilis specifically.
"Horse crippler" cactus
Anyway. I also saw the odd horse crippler cactus (Echinocactus texensis), so named because it hides semi-submerged in the dirt and is hard to spot. Supposedly, horses step on it. Looks like a deer knew to step around it. I'm a little skeptical as to how many horses have been crippled by this cactus. It makes me think about how in the upper Plains everyone's convinced horses are killing themselves by tripping on prairie dog burrows. Are they really so fragile? Does that really happen?

Blooming stretchberry sheltered by cedar
What I did not see was a ton of flowers. Spring is behind the metroplex in Copper Breaks. While our stretchberry (elbow bush, Forestiera pubescens) was blooming on Valentine's Day, theirs just started. I did see the standing dead stalks of gayfeather (Liatris spp.) and a number of composites, but very little new growth had been put on for the season.

Signs of life were mostly mammalian. Coyotes had heavily marked the trails with their scat, delineating the borders of their territory. When one of my neighbors at the campground fired up their grill (or other appliance…), it made a high-pitched keen and the coyotes were close enough to hear it and respond immediately. I also saw a rabbit out at dusk.

While it was early in the season, I did enjoy getting out somewhere nearby that looked so different from home. These little weekend trips help keep me grounded when I get to feeling desk-bound.

Sunday, March 8, 2015

Galls are a good thing*

*Or at least, mostly harmless.
Galls on an oak tree. Probably mealy oak gall (Disholcapsis cinerosa).
Lately, I feel like my blog's tagline could be "It's just aesthetics: leave well enough alone." First I defended mistletoe, then tent caterpillars, now gall wasps. I have noticed more oak galls in Texas than anywhere else I've lived. When I visited Dinosaur Valley State Park on Saturday, some trees were hung so thickly with them they looked like persimmon fruits. Others, which had supported leaf galls instead of twig galls, instead looked like they had odd round red acorns scattered about their trunks. You can get an idea for which critter created the gall by its appearance.

Gall wasps (Cnipidae) are the creatures that create the little brown orbs hanging in your oak trees. These cryptic creatures spend most of their lives as grubs. Adults are the size of a fruit fly and live about a week. They emerge, mate (every other generation), and then oviposit their eggs in stems, leaves, and twigs of oak trees all within that brief window. Note I didn't say "eat". Adult gall wasps don't eat- they live entirely of the plant matter they consumed as grubs inside their gall. They alternate generations between asexual females (who live in one type of gall), and sexually reproducing males and females (who live in another).
Another type of gall. Possibly Belonocnema kinseyi.
The galls themselves are an abnormal plant growth. They are not directly created by the wasps, but instead are similar to an immune effect in the host tree. There is consensus that this gall-making does not seem to hurt the host. The impact is so minuscule when weighed against the mass of the tree, it does not do measurable damage. I suppose it's like when you knick yourself shaving. You might bleed a little, but beyond the initial cut you don't suffer for it. I could not find a single source suggesting that galls harmed trees or required intervention. Most sources suggested doing nothing at all in response to an "infestation". The galls are not a danger, and they are only a problem if their untidy looks bother the homeowner.
A closer look at possible B. kinseyi galls.
Bizarrely, gall wasps are prevented from becoming super abundant because there are more trophic levels above them: they themselves are parasitized by a different kind of wasp.  Then, the wasp which parasitized the gall wasp is parasitized by ANOTHER kind of wasp. Nature just doesn't quit. It seems that being born a wasp is an awful tough way to make a living. An interesting effect this hyperparasitism has on the casual naturalist is that you have no idea if the bug which emerges from the gall is the one that built it. You could say that the gall structures the first wasps create serve as protective homes for many other insects. At a minimum, they provide an example of intense competition within the animal kingdom.