Some thoughts about springtime gardening, from my piece in Houzz.com this week.
“The garden is not an escape into domineering control of nature; rather it requires sustained attention to the interconnections of life.”
Some thoughts about springtime gardening, from my piece in Houzz.com this week.
“The garden is not an escape into domineering control of nature; rather it requires sustained attention to the interconnections of life.”
My musings on leaf biology, familiar to Ramble readers who might remember my fungus experiment, are featured in this month’s NPR blog. I wrote a guest article discussing the networked nature of maple leaves (and all life…).
I’ve been on the road giving readings from The Songs of Trees. Thank you to all who’ve come out! Upcoming venues include Nashville, Portland (OR), Corvallis, San Francisco, Denver, and Pasadena. I’ll be in Asheville, St Louis, Millbrook (NY), and Maryland later in the season. I hope to have one or more NYC events as well.
If you’ve read the book and have thoughts about its stories and voice, please submit comments/review at Amazon’s book page!
New book, published today:
After five years of growth in the underground humus of writing and editing, The Songs of Trees: Stories from Nature’s Great Connectors has lifted its leaves into the sunlight.
Ed Yong, writing this morning in The Atlantic.com, gives a great overview of the book.
You can purchase the book at bookstores or online. Many libraries have copies on the shelves. Links to bookstores:
Over several years I visited a dozen trees, sitting with each to listen to its story. The trees are located in very different places – the Amazon rainforest, Shakerag Hollow in Sewanee, the Damascus Gate in Jerusalem, a city park in Denver, an ancient hearth in Scotland – but they all, in their own ways, tell of life’s surprising interconnections.
The book’s web pages have more information about the book, including sound clips, photographs, a Q&A, and advance praise from writers and scientists. Outside Magazine just published a profile of my work by Paul Kvinta, featuring the Manhattan street tree that I befriend in one of the book’s chapters.
I hope you’ll enjoy these tales of biology and human culture. I’d be very grateful if you’d consider sharing news of the book’s publication with friends and family.
With my gratitude,
Lectures and readings:
I’ll be speaking at the following venues in the coming months, with more to be announced soon. I’d love to see you there. If you have friends or family who might be interested, please pass along the date.
Tacoma, WA: Slater Museum, University of Puget Sound. April 7th, 2pm.
Tacoma, WA: King’s Books. April 7th, 7pm.
Seattle: Town Hall Seattle, 1119 8th Ave, Seattle, WA. April 8th, 7:30pm.
Cambridge/Boston, MA: Arnold Arboretum and Harvard Museums of Science and Culture. 6pm, April 12th, 2017.
Sewanee, TN: University of the South. Convocation Hall. 4:30pm, April 17th.
Chattanooga, TN: Benwood Auditorium, University of Tennessee Chattanooga. April 18th, 7pm. Lecture to benefit Tennessee River Gorge Trust. Hosted by the UTC Department of Biology, Geology and Environmental Science.
Oxford, MS: University of Mississippi. April 20th, 2017.
Atlanta, GA: Atlanta Audubon and Chattahoochee Nature Center. 6pm, April 22nd, 2017, reservation required. (Location: Chattahoochee Nature Center, 9135 Willeo Road, Roswell, GA 30075)
Nashville, TN: Parnassus Books. April 30th, 2pm.
Portland, OR: Powell’s Books. May 3rd, 2017. (7:30pm, Powell’s City of Books, 1005 W. Burnside St., Portland.)
Denver, CO: Tattered Cover Bookstore. 7pm May 4th, 2017. (LoDo store: 1628 16th Street, Denver)
Point Reyes Station, CA: Point Reyes Books. May 7th, 2017.
San Francisco, CA: California Institute of Integral Studies. May 10th, 2017.
Pasadena, CA: Vroman’s Bookstore. 7pm, May 11th, 2017.
Asheville, NC: Malaprop’s Bookstore. May 31st, 2017.
Easton, MD: Adkins Arboretum. June 8th, 2017. 4pm – 6pm at the Academy Art Museum 106 South Street.
Millbrook, NY: Cary Institute of Ecosystem Studies. June 9th.
Sewanee, TN: Young Writers’ Conference. July 10th, 2017.
St Louis, MO: Missouri Botanical Garden. July 25th, 2017. Wild Ideas Worth Sharing Speaker Series and Visualizing Biodiversity for a Better World.
Byron Bay, Australia: Byron Bay Writers Festival. August 4-6, 2017.
Canberra, Australia: National Library of Australia. August 9th, 2017.
Bendigo, Australia: Bendigo Writers Festival. August 11-13, 2017.
Nashville, TN: Southern Festival of Books, Nashville, TN. Oct 13th and 14th, 2017.
Fairlee, VT: Northern Woodlands Conference. The Hulbert Outdoor Center. Oct 20th-22nd, 2017.
Birmingham, AL: Audubon Society. Dec 7th, 2017.
“Yet mark’d I where the bolt of Cupid fell:
It fell upon a little western flower,
Before milk-white, now purple with love’s wound”
Hepatica unfurls its advertisements in both white and purple. This is true of North American species and those in Asia. Why the variation? Natural selection or genetic drift eliminates variation in a population unless some force keeps these purgative pressures at bay. In the case of Hepatica, the costs and benefits of white and purple flowers have not been measured in the wild (readers, correct me if I’m wrong here, please!). Midwestern populations are more purple than their eastern cousins.
Could pollinators or the light environment be creating different selection pressures? Many populations contain a mix of colors (white is the most common here in Sewanee, but purples are scattered among them in significant numbers), so selection does not seem to favor just one color in each location.
In spring beauty flowers (Claytonia), flowers come in red, white, and intermediate. Natural selection acts on flower color in this species complex ways. Redder flowers are more attractive to pollinators, but whiter flowers have more flavonols, chemicals that act as herbivore deterrents. So, white flowers receive fewer pollinators but red flowers get more damage from slugs. Damage from herbivory changes from year to year and from place to place. So two opposing forces — pollination and herbivory — vary in space and time, resulting in a mix of flower colors. Perhaps a similar turbulent, Puckish convergence of forces also acts on Hepatica?
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:
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
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”
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.”
So says Mr. Frost.
As wildflowers emerge, they briefly take on a sleek, streamlined form as they swim upward through the duff.
Some photos of these rising hopefuls from the last few weeks in Shakerag Hollow, toadshade trillium, bloodroot, May apple:
A bolt knocked the crown off this tulip poplar, splitting the tree down to the roots in the process. A fire then started in the split trunk, hollowing it out. Now the trunk is a tube, entirely charred inside. In the mid-section of the tree the bark and remaining wood is no more than a few centimeters thick. Up top, several branches are still alive.
Trees are not the only witnesses to lightning strikes. NASA detects “flash rates” of lightning across the globe from sensors in orbiting satellites. The image below uses this NASA data to map lightning strikes (fromNOAA’s Science on a Sphere project; click on “view interactive sphere” on the right-hand side of the page to view your own part of the world). Map projection: from orbit, where North means nothing.
On the lakeshore, a smell of springtime mud and wet leaves. Soil microbes are getting a boost from the unseasonably warm air and our noses are soaked in their festivities, an aroma-pulse of decomposition.
I push forefinger against thumb, then flick, I tap an alder catkin. A cloud of lime-yellow pollen drifts down to the lake water.
Alders are monoecious, that is they have separate male and female flowers on the same plant. The male flowers mature before the females, preventing self-pollination.
Male flowers hang in pendulous catkins. They are furry, soft, floppy, cute. Like kittens, hence the name. From 16th century Dutch, katteken, a little cat.
Later in the year the female flowers will swell and harden into small cone-like strobili. These look like cones, but alder is a flowering plant, an angiosperm not a cone-bearing gymnosperm like a pine.
A little early for flowering? Not any more. Plants are shifting their bloom and bud-break earlier as the climate warms. For example, a study in the Washington DC area found that over the last 30 years of the 20th century, alder moved its blooming date 11 days earlier. Most species are following suit, but not all at the same rate. Non-native species like privet, bittersweet, and multi-flora rose are less tied to native seasonal rhythms and so are better able to exploit the early springtime warmth.