Tag Archives: shakerag hollow

Spring is dead, long live the spring (my New York Times piece on “global weirding” of the seasons)

I have an opinion piece in today’s New York Times. I will run in the Sunday print edition. Regular readers of Ramble will recognize some of the scenes and characters: bloodroot and foxes in Shakerag Hollow. I hope you’ll consider reading, sharing, and commenting. The Times loves to see reader engagement. So far, people are weighing in with their own experiences and thoughts about the seasons.

The Times requires a fact-checked version of articles from all contributors. I’ve pasted below a shortened version of what I provided to them (minus the pdfs of relevant scientific articles and some longer quotes from papers). In the so-called “fake news” era, it’s important to note that some news outlets have a strong commitment to getting the facts right. Whether we agree with “opinion” is another matter, of course.

Abbreviated list of sources:

Observations of early spring:

Peepers calling in Nashville: Personal observation at Shelby Bottoms, on Jan 28th (with chorus frogs) and Feb 11th (in very large numbers). (Feb 22nd with other frogs in large numbers, Lake Cheston, Sewanee, TN.)

Red maples in bloom in New York before snow storm:



Bloodroot in February: In Shakerag Hollow, Sewanee, TN, Feb 24th several in full bloom.

Flying queen ants and spring azures: Feb 19th. Elliott Point, Sewanee.

Emergence dates for quince, multiflora rose, Bradford pears: in the town of Sewanee, TN.

Teens in March: nights of March 14th and 15th in Sewanee, TN.

Privet, bittersweet and honeysuckle earliest to leaf out: In Sewanee, TN.

Changes in phenology in northern hemisphere:

2.8/days per decade is from: Parmesan, Camille. “Influences of species, latitudes and methodologies on estimates of phenological response to global warming.” Global Change Biology 13.9 (2007): 1860-1872.

“A meta-analysis spanning 203 species was conducted on published datasets from the northern hemisphere.” “Analyses here on a new expanded dataset estimate an overall spring advancement across the northern hemisphere of 2.8 days/decade”

See also (same trend, somewhat different quantification of  rates):

Abu-Asab, Mones S., et al. “Earlier plant flowering in spring as a response to global warming in the Washington, DC, area.” Biodiversity and Conservation 10.4 (2001): 597-612.

Jeong, Su‐Jong, et al. “Phenology shifts at start vs. end of growing season in temperate vegetation over the Northern Hemisphere for the period 1982–2008.” Global Change Biology 17.7 (2011): 2385-2399.


Schwartz, Mark D., Rein Ahas, and Anto Aasa. “Onset of spring starting earlier across the Northern Hemisphere.” Global Change Biology 12.2 (2006): 343-351.


“Results are consistent with prior smaller area studies, confirming a nearly universal quicker onset of early spring warmth (spring indices (SI) first leaf date, −1.2 days decade−1), late spring warmth (SI first bloom date, −1.0 days decade−1; last spring day below 5°C, −1.4 days decade−1), and last spring freeze date (−1.5 days decade−1) across most temperate NH land regions over the 1955–2002 period.”

Time lapse, National Phenology Network, cherries, and NOAA temperature data:

Time lapse: https://www.nytimes.com/interactive/2017/03/08/climate/early-spring.html

Phenology network: https://www.usanpn.org/

Cherry bloom in Washington DC: https://www.nps.gov/subjects/cherryblossom/bloom-watch.htm

And, for damage from combination of warm February then March freeze: https://www.washingtonpost.com/news/capital-weather-gang/wp/2017/03/09/cherry-blossoms-could-be-seriously-damaged-by-upcoming-cold-snap/?utm_term=.d1f4902fcbde

NOAA data on February temperature records: http://www.noaa.gov/news/us-had-2nd-warmest-february-and-6th-warmest-winter-on-record “Most locations across the contiguous U.S. were warmer than average during February. Thirty-nine states from the Rockies to the East Coast were much warmer than average, with 16 states across the South, Midwest, Mid-Atlantic and Northeast record warm. Below- to near-average temperatures were observed for the Northwest, with no state ranking record cold.” And, in the final report: https://www.ncdc.noaa.gov/sotc/national/201702 “Thirty-six states had maximum temperatures that were much above average, with 19 states in the Southern Plains, Midwest, and along the East Coast having record warm maximum temperatures.”

NOAA projections for next 2-3 months: http://www.cpc.ncep.noaa.gov/products/predictions/long_range/seasonal.php?lead=1

The USA National Phenology Network

Maps are based on:

“The Real-Time Mesoscale Analysis (RTMA) is a NOAA/NCEP high-spatial and temporal resolution analysis/assimilation system for near-surf ace weather conditions. Its main component is the NCEP/EMC Gridpoint Statistical Interpolation (GSI) system applied in two-dimensional variational mode to assimilate conventional and satellite-derived observations. “ http://nomads.ncep.noaa.gov/txt_descriptions/RTMA_doc.shtml

And on:

Ault, T. R., M. D. Schwartz, R. Zurita-Milla, J. F. Weltzin, and J. L. Betancourt (2015): Trends and natural variability of North American spring onset as evaluated by a new gridded dataset of spring indices. Journal of Climate 28: 8363-8378.

“This dataset is derived from daily interpolated meteorological data, and results are compared with historical station data to ensure the trends and variations are robust. Regional trends in the first leaf index range from −0.6 to −1.7 days per decade, while first bloom index trends are between −0.2 and −1.4 for most regions.”

Summary of model at: https://data.globalchange.gov/report/indicator-start-of-spring

“The model is based on (1) long-term observations of lilac and honeysuckle first-leaf and first-bloom, collected by citizen science volunteers at hundreds of sites across the contiguous United States, and (2) daily minimum and maximum temperatures measured at weather stations.”


Satellite data on changing seasonality around the globe:

Buitenwerf, Robert, Laura Rose, and Steven I. Higgins. “Three decades of multi-dimensional change in global leaf phenology.” Nature Climate Change 5.4 (2015): 364-368. http://www.nature.com/nclimate/journal/v5/n4/full/nclimate2533.html

“We found that leaf phenology changed substantially in most regions of the world, with 95% of the land surface changing by at least 1 s.d. for at least one metric.” And “We show that the phenology of vegetation activity changed severely (by more than 2 standard deviations in one or more dimensions of phenological change) on 54% of the global land surface between 1981 and 2012.”


Climate change and plant invasions:

Bradley, Bethany A., David S. Wilcove, and Michael Oppenheimer. “Climate change increases risk of plant invasion in the Eastern United States.” Biological Invasions 12.6 (2010): 1855-1872.


“Climate change is likely to enable all three species to greatly expand their ranges. Risk from privet and kudzu expands north into Ohio, Pennsylvania, New York, and New England states by 2100. Risk from cogongrass expands as far north as Kentucky and Virginia. Heightened surveillance and prompt eradication of small pockets of invasion in northern states should be a management priority”

See also:

Polgar, Caroline, Amanda Gallinat, and Richard B. Primack. “Drivers of leaf‐out phenology and their implications for species invasions: insights from Thoreau’s Concord.” New Phytologist 202.1 (2014): 106-115.


“Woody species are now leafing out an average of 18 d earlier than they did in the 1850s, and are advancing at a rate of 5 ± 1 d °C−1.” “…invasive shrubs generally have weaker chilling requirements … leaf out faster in the laboratory and earlier in the field; native trees have the strongest chilling requirements.”

Hulme, Philip E. “Contrasting impacts of climate‐driven flowering phenology on changes in alien and native plant species distributions.” New Phytologist 189.1 (2011): 272-281.


“Native plant species whose phenology did not track climate change declined in distribution, whereas species that became more widespread all exhibited earlier flowering. In contrast, alien neophytes showed both a stronger phenological response to warming and a more marked increase in distribution, but no link between the two.”


Timing of birds:

La Sorte, Frank A., et al. “The implications of mid‐latitude climate extremes for North American migratory bird populations.” Ecosphere 7.3 (2016).


“Our findings suggest short-distance migrants are more flexible and resilient, whereas populations of long-distance migrants are at a distinct disadvantage, which may intensify if the frequency of these events increases.”

Both, Christiaan, et al. “Climate change and population declines in a long-distance migratory bird.” Nature 441.7089 (2006): 81-83.


“In a comparison of nine Dutch populations, we find that populations have declined by about 90% over the past two decades in areas where the food for provisioning nestlings peaks early in the season and the birds are currently mistimed. In areas with a late food peak, early-breeding birds still breed at the right time, and there is, at most, a weak population decline.”

Møller, Anders Pape, Diego Rubolini, and Esa Lehikoinen. “Populations of migratory bird species that did not show a phenological response to climate change are declining.” Proceedings of the National Academy of Sciences 105.42 (2008): 16195-16200.


“Species that declined in the period 1990–2000 did not advance their spring migration, whereas those with stable or increasing populations advanced their migration considerably. On the other hand, population trends during 1970–1990 were predicted by breeding habitat type, northernmost breeding latitude, and winter range (with species of agricultural habitat, breeding at northern latitudes, and wintering in Africa showing an unfavorable conservation status), but not by change in migration timing.”

Plasticity in the timing of breeding for songbirds:

Dunn, Peter O., and David W. Winkler. “Effects of climate change on timing of breeding and reproductive success in birds.” Pages 113-128 in Effects of climate change on birds (2010, Oxford Univ Press). Eds: A. P. Møller, W. Fiedler, P. Berthold.

“Plasticity in the timing of breeding appears to be relatively high in many songbirds…because in different years some individuals may vary their breeding dates by almost a month in response to local weather conditions” “Evidence for long-term changes in the phenology of birds is accumulating rapidly from around the world.”

Biological processes affected by climate change:

Scheffers, Brett R., et al. “The broad footprint of climate change from genes to biomes to people.” Science 354.6313 (2016): aaf7671.


“To do this, we identify a set of core ecological processes (32 in terrestrial and 31 each in marine and freshwater ecosystems) that underpin ecosystem functioning and support services to people. Of the 94 processes considered, 82% show evidence of impact from climate change in the peer-reviewed literature.”


Human psychology of climate change:

van der Linden, Sander, Edward Maibach, and Anthony Leiserowitz. “Improving public engagement with climate change: Five “best practice” insights from psychological science.” Perspectives on Psychological Science 10.6 (2015): 758-763.


Also, not directly cited in final version:

Climate change effects in the ocean:

Poloczanska, Elvira S., et al. “Global imprint of climate change on marine life.” Nature Climate Change 3.10 (2013): 919-925.


“We found spring phenology in the ocean has advanced by 4.4±0.7 days dec−1 (4.7±1.1 days dec−1 excluding single-species studies) and summer phenology by 4.4±1.1 days dec−1 (4.0±0.6 days dec−1 excluding single-species studies; Fig. 2b and Table 1).”

“The timing of phytoplankton blooms advanced much faster (6.3±1.6 days dec−1 for multispecies assemblages) than that of plants on land (1.1–3.3 days dec−1; refs 12, 20). Fastest rates of spring advancement were for pelagic animals (invertebrate zooplankton 11.6±2.9 days dec−1, and larval bony fish 11.2±1.7 days dec−1 and Fig. 2b). However, phyto- and zooplankton groups both show slower, and similar, advancement of summer phenology (phytoplankton: 4.6±0.4 days dec−1; invertebrate zooplankton: 4.6±1.0 days dec−1).”


Climate change proceeding at different rates:

Thackeray, Stephen J., et al. “Trophic level asynchrony in rates of phenological change for marine, freshwater and terrestrial environments.” Global Change Biology 16.12 (2010): 3304-3313.



Post, Eric, et al. “Ecological dynamics across the Arctic associated with recent climate change.” science 325.5946 (2009): 1355-1358.



Thomas, Chris D., et al. “Extinction risk from climate change.” Nature 427.6970 (2004): 145-148. http://www.nature.com/nature/journal/v427/n6970/abs/nature02121.html


Fu, Yongshuo H., et al. “Declining global warming effects on the phenology of spring leaf unfolding.” Nature 526.7571 (2015): 104-107.


“Using long-term in situ observations of leaf unfolding for seven dominant European tree species at 1,245 sites, here we show that the apparent response of leaf unfolding to climate warming (ST, expressed in days advance of leaf unfolding per °C warming) has significantly decreased from 1980 to 2013 in all monitored tree species. Averaged across all species and sites, ST decreased by 40% from 4.0 ± 1.8 days °C−1 during 1980–1994 to 2.3 ± 1.6 days °C−1 during 1999–2013. The declining ST was also simulated by chilling-based phenology models, albeit with a weaker decline (24–30%) than observed in situ. The reduction in ST is likely to be partly attributable to reduced chilling.”


Pollinators, come get it

Shakerag Hollow continues its tumble through spring. The earliest blossoms are gone and fruits are fattening in their place. So goes the bloom of youth. The later flowers have now stepped forward and are waving for all they’re worth at the motley collection of pollinating bees, wasps, and flies. A few of my favorites:

Hepatica. Most bloomed weeks ago; a few persist.

Hepatica. Most bloomed weeks ago; a few persist.

Larkspur. So violet it makes your eyes hurt.

Larkspur. So violet it makes your eyes hurt.

Wild geranium. A lighter shade of pale?

Wild geranium. Violet calmed.

Spotted Mandarin. Coolest name in the woods.

Spotted Mandarin. Most fabulous name in the woods.

Celandine poppy. The zenith.

Celandine poppy. The zenith. The nonpareil.

Begone umbral winter

The spring equinox has passed, so light has the upper hand now. Darkness creeps away.

The plants in Shakerag Hollow know this and are starting to crack out of their winter shells.

Bloodroot. Waiting, waiting for bees.

Bloodroot. Waiting, waiting for bees.

Spicebush: female flower. These will turn to the bright red drupes so loved by migrant birds. Fast food for autumnal  avian wanderers starts right here.

Spicebush: female flower. These flowers will turn into the bright red drupes so loved by migrant birds. Fast food for autumnal avian wanderers starts right here.

Spicebush: male flower. This species is dioeceous, meaning that each plant is either male or female with, no doubt, a few exceptions.

Spicebush: male flower. Spicebush is dioecious, meaning that each plant is either male or female with, no doubt, a few individuals that break the rules.

Above, the robber baron trees are constrained by their size to delay leafing out. In the delay, a herbaceous and shrubby party below.

Above, the robber baron trees are constrained by their size and must delay leafing out until hard freezes are over. They keep Lent, it seems. The pagans below the canopy live under a different set of rules and hold a weeks-long herbaceous party.

Ice flowers in Shakerag Hollow

The temperature dropped to minus five last night (minus twenty for disciples of Anders Celsius), the coldest that I’ve seen in Sewanee. I took a walk in Shakerag Hollow this morning to see how the woods were faring in this unusual chill. I’ve never experienced such silence here. The quiet was punctuated by woodpeckers drilling meager breakfasts from high in the canopy and trees occasionally snapping out gunshot sounds as their wood shattered. No sign of wrens, titmice, chickadees. The forest floor was mostly clear. Only a few deer tracks. Most birds and mammals are in hunker-down mode.

Amazingly, given the cold, the springs were still running. This flowing water created some beautiful ice formations on the rocks all around. When water vapor rises from the stream, it hits cold, dry air. This is an unstable mix, ripe for an encounter with a pointy nucleation site: an icy strand of moss or rock edge. Once they get started, these crystals build on themselves, growing “flowers” from the air. An icy foreshadow of the spring ephemerals? The largest ones are a couple of inches across. Similar formations are found in polar seas and host very unusual communities of bacteria.

So welcome to Tennessee, Polar Vortex. Here are your blooms:


Red: A ticket outta here (for travelers that have already come a long, long way)

The coming wave of songbird migration has plants getting excited: finally they can get the kids out of the house before winter’s rigors set in. As thrushes, vireos and warblers move southward by the millions, their hunger creates an opportunity for seed dispersal that many plants have grabbed with enthusiasm. Look around in the late summer woods and you’ll see berries fattening up, preparing the bribe for passing birds. Bright red is the color of choice, the hue most likely to seduce an avian eye, so berries tend toward the garish, not the subtle blush.

We’re a few weeks away from the peak of migration (late September through early October brings the largest numbers), but the plants are ready. These eager food vendors include spicebush, dogwood, yellow Mandarin, Jack-in-the-pulpit, and Solomon’s plume.

prosartes lanuginosa fruit

Fruit of Yellow Mandarin (also known as Fairybells, Prosartes lanuginsoum)

Jack-in-the-pulpit fruits (Arisaema triphyllum)

Jack-in-the-pulpit fruits (Arisaema triphyllum)

Fruits of Solomon's plum (Yellow Mandarin (Maianthemum racemosa). Often also called "False Solomon's Seal."

Fruits of Solomon’s plume (Maianthemum racemosa). Often also called “False Solomon’s Seal.”

Yellow Mandarin has an interesting family tree. It has a few siblings in North America, but all its other close relatives are Asian species. This whole clan was for years classified in one genus, Disporum, but the North American species are now recognized as distinct enough to merit placement in their own genus, Prosartes. Solomon’s plume and Jack-in-the-pulpit also have close relatives in Asia. This Asia-America connection is echoed by the biogeography of many other species, especially among the plants of the Southern Appalachians which often have close affinities to species in East Asia. Boufford and Spongberg, scientists from the Harvard Herbaria, summarized the situation:

The similarities of the forests of Japan, central China, and the southern Appalachians in appearance as well as in ecological associations are in many instances so great that a sense of déjà vu is experienced by botanists by one of the regions visiting the other.

The list of Appalachian species with very close East Asian kin is long and, surprisingly, is much longer than the same list for plants with close kin in western North America. Japan is closer than Oregon, it seems. A few of the more familiar examples include: tuliptree, magnolia, dogwood, Virginia creeper, mayapple, ginseng, partridge-berry, blue cohosh, witch hazel, and honey locust. And, of course, the aptly-named “Mandarin.”

Donoghue and Smith’s analysis of this pattern concludes that close evolutionary connections between East Asian and Eastern North American species are “exceptionally common in plants, apparently more so than in animals.” Their work suggests that “many temperate forest plant groups originated and diversified within East Asia, followed by movement out of Asia at different times, but mostly during the last 30 million years.”

These botanical connections are reminders that Asian and American temperate forests were once connected, a connection that was severed as the world dried and cooled in the late Cenozoic. But it is also the result of a few long-distance dispersal events between climatically similar areas.

Animals move to the beat of a different biogeographic drummer. Their kinship patterns are more predictable: western and eastern North America share many close relatives, connections south to the tropics are also common.

So the migration of American birds is powered by Asian food. The botanical restauranteurs hope that the birds opt for the take-out option, carrying seeds away from the parental storefront. Most of these seeds will land a few meters from the parents, but a very small number might make a huge leap, perhaps landing in southern Mexico or on the coast of South America. There, they’ll likely perish. But the biogeographic future is written by the one or two that can put down roots and flourish.

The same is unfortunately true for plant diseases. A few long-distance migrants are reshaping the forests of the world. It is no accident that so many of the more notable plant-killing invasive diseases in the Southern Appalachians have their origins in Asia. Once they get over here they find a “home way from home,” minus the constraints that they experienced in their homeland.

I’ve rambled about the color red before, both here on the blog (“Quite possibly the most overused image of North American birdlife”) and in The Forest Unseen (“November 5th — Light”). I’ll note briefly here that until the leaves fall in a few weeks, the plants face an uphill battle against the physics of light in the forest. It is dark in the woods these days (photography is impossible without steadying the camera on my boot or using a flash). The summer tree leaf canopy is not only robbing most of the light, it is selectively stripping out the reds. Only when a shaft of sun sneaks through a canopy opening do these fruits truly shine. As autumn comes on, the botanical beacons will light up more often.

Thrushes: get ready.

Dead wood, ashes.

One of Shakerag Hollow’s giant trees has fallen. An ash that until last week held its arms in the highest reaches of the canopy now sprawls across the forest floor, its body utterly torn. I’ll go back soon and “measure” things (how tall? what weight of wood came slamming down?), but for now: just awe.

I did not see the fall, but came by soon after. The trunk was … indescribable. Some grand words are needed, for barely imaginable violence had been at work. Rent asunder!? The whole wide trunk was twisted and split open, lengthways, in several long gashes. Other trees, themselves no mere saplings, were smashed into the ground. Large boulders were shifted as roots reared and cracked. The air was infused with the odor of fresh-split wood. An overtone of bitterness, like cut oak, but mostly a sweet smell, almost honeyed.

I found the tree in the morning and returned in later in the day for another look. As I stepped closer in the warm afternoon, I hesitated then held back. There were wasp-like creatures, big ones, swarming over one of the thick exposed roots. These insects were scurrying, flickering their wings, crawling over each other. A frenzy.

Black with bold yellow stripes. Buzzing as they flew. Had the tree fall unearthed a buried wasp nest?

Neoclytus caprea

But something was not quite right about these wasps. I moved forward slowly and saw their fat hind legs, too beefy for a wasp. Crickets? No. Then the wing cases, striped in black and yellow: beetles! Wasp-mimicking beetles of some kind. I moved to the side of the tree and saw hundreds of them, racing up and down the bark. They were on no other trees nearby. Half of the beetles were copulating; the other half seemed intent on colliding with the mating pairs. Even though I now knew that they were harmless, their waspy nature made me cautious. Even their short curved antennae were creepily hymenopteran in style (oh yes, those hymenoptera have style).

Who were they? To identify them, I spent some time in the online funhouse known as the Photographic Atlas of the Cerambycidae of the World. This is an amazing site devoted to a single family of beetles, the so-called longhorns (although many of them do not have long antennae). The family contains twenty thousand species, an impressive number when we remember that there are fewer than six thousand mammal species. Some of these cerambid beetles run afoul of humans when they bore into trees and wood that we’d rather they stayed out of. A few of them are “invasive exotics,” killing off native plants. But the beetles in Shakerag were natives: Banded Ash Borers (Neoclytus caprea (Say) 1824). They have an interesting life history, finding recently downed ash and oak trees, then laying their eggs in the bark. The larvae then chew on the wood below the bark, emerging next spring to start the hunt for a newly downed tree.

So I was not the only creature in Shakerag following my nose to the smell of ripped up wood. How many huge ash trees have fallen lately? Not many. Every banded borer within miles must have been at this party. Those flickering antennae are surely tuned to the chemical particularities of newly opened ash wood.

The beetles were one of the very first arrivals in the tree’s new existence. When a large tree falls, its ecological life still stretches out into the future. Perhaps half of the animals (and many more of the fungi) that the tree will nurture during its existence arrive after the tree has fallen. The ecological vitality of a forest can be judged by how may large trees are lying around, feeding beetles, hiding salamanders, growing fungi.

To paraphrase Mr. Faulkner, “Dead wood is never past, it’s not even dead.”