Science Magazine and the Guardian
February 2020

Climate change could increase bumble bees’ extinction risk as temperatures and precipitation begin to exceed
species’ historically observed tolerances. A new study adds to a growing body of evidence for alarming, widespread losses of biodiversity and for rates of global change that now exceed the critical limits of ecosystem resilience.


Read more about this topic here and here, or read the research study here.

Ask someone what they know about praying mantids and chances are they’ll bring up the female biting the male’s
head off during mating. It happens, albeit only about 17 percent of the time, but those deaths can be a surprisingly
useful tool when studying mantid population changes over time. It’s one of the pieces of information tracked by
Lawrence Hurd, Ph.D., a professor of biology at Washington and Lee University, during a 20-year study
(1999-2018) of Tenodera aridifolia sinensis, the Chinese praying mantid.
The results were published in January in Annals of the Entomological Society of America.

In the last few years, studies finding widespread declines in insect abundance have made headlines. Hurd’s
long-term study uses one insect in one northern Virginia field to show how such declines can happen. Although the study only followed one species, Hurd and coauthorsnote that the findings should apply to other insects and spiders with a similar life cycle.

For this study, Hurd made good use of his resources. He had an insect of unusual size (7-10 centimeters) that beginners (his college ecology lab students) could easily recognize and catch. He also had a nearby field beginning its natural succession, which functioned as a laboratory because the mantids couldn’t easily escape from it. No other suitable fields were close by, and the mantids aren’t very mobile.

Five times between 1999 and 2018, on approximately the same day in September, Hurd sent his students across the
field in a “skirmish line” to collect, mark, and note every possible T. a. sinensis. Hurd writes in an email, “I always
try to base it [the class] on gathering good, usable data instead of just make-work data collection on a question that
has already been answered.”

To assess the reproductive success of the mantids, they went back after the first frost to collect the oothecae (eggs
laid in a gooey substance that hardens into a protective case). They brought the oothecae back to the lab, weighed them, and then returned them to the field. For the oothecae found on the stems of herbaceous plants, that meant “tying [them] on with sewing thread run through the dried foam surrounding the eggs.” Mantids do well in flowery fields with lots of arthropod prey. When succession trends in an area lead to more trees, the population of mantids should shrink. Over the 20 years of this study, two-thirds of the open field area was replaced by trees, and the number of mantids decreased dramatically.

However, succession was not the only factor impacting the mantids—climate change was as well. When a Chinese praying mantid lays her eggs, the sex ratio is even. By the time the mantids reach adulthood, males outnumber females. Once mating begins, the percentage of males starts to fall, prey to the females as well as any other
predators in the field. Eventually, the females become more common. Even though Hurd and the students sampled on essentially the same calendar day (September 12, 13, or 14) each year, they found that the proportion of males to the total population declined from more than 60 percent in 1999 to about 25 percent in 2018, showing that the mantids were further along in their life cycle.

It’s no surprise. For the last 40 years the growing season in northern Virginia has gotten longer and the summers hotter, so the mantids both hatch and reach maturity earlier. This means that some eggs may hatch before frost can put them into diapause, leading to death of the young nymphs and potentially adding to the population losses caused by the successional change.

In 2018, Hurd and his students found only three oothecae. In the fall of 2019, he saw no mantids, and found no oothecae after the first frost.

This study demonstrates the potential double whammy of habitat loss—even a naturally occurring one—and climate change. Hurd writes, “People are becoming worried about having to include insects in the mass extinction episode that many (including me) feel is already underway.” He says when he talks about this, people often respond with, “‘We gotta worry about bugs, too?'”

Unfortunately, as this study illustrates, the answer to that question is “yes.”

​Find this article in Entomology Today here.

​Find other articles on declines in insects and biodiversity on the Reading Corner page.

by Jeff Stehm
 
We are often caught up in the here and now, or at best, think only in human time scales. But have you ever wondered about what Shenandoah National Park looked like millennia ago or might look like a millennium in the future?
 
Shenandoah National Park today hosts a rich Appalachian Oak forest consisting of hickory, maple, and tulip poplar, with oak as the dominant tree species. Pine predominates on warmer southwestern faces of the southernmost hillsides. In cooler areas with northeastern aspects, small, dense stands of moisture loving hemlocks exist.
 
The average annual temperature in the Park is about 46.5°F at Big Meadows (located in the north central area of the Park), and ranged from about 44°F to a little over 50°F over the last 75 years.
 
Forty-five thousand years ago it was a very different place. North America was in the midst of the last throws of the ice age. Temperatures fluctuated (over centuries) from cold to warm and back again. Litwin et al. (2004) estimated that the mean annual temperatures around Big Meadows varied about 20°F over the 45,000 year period, ranging from about 35°F to 55°F. In today’s climatic terms, these variances in temperature was equivalent to those existing today from latitude 55°N (Northern Newfoundland) to 32°N (Georgia).
 
Such temperature swings profoundly affected the forests of Shenandoah National Park. The Park experienced temperatures almost 10°F colder to 5°F warmer – enough to shift forest biomes drastically back and forth between cold artic boreal forests and warm Oak-Hickory-Pine and Southern Mixed forests.

​

Forest biomes shifted back and forth a minimum of 37 times during the last 45,000 years as shown below.

Forest Type                                             Years Ago                                              Climate

Boreal                                                         45,000-37 000                                    Cold

Northern Hardwoods                        36,000-35,000                                   Warming

Northern Harwood-Spruce            32,000                                                     Cooling

Boreal                                                          28,000                                                     Cold

                                                                         27,000                                                      Last Glacial Maximum

Northern Hardwoods                        26,000                                                     Warming

Boreal                                                          25,000                                                     Cold - Northern Hemisphere Insolation Minimum

Northern Hardwood-Spruce         24,000                                                     Warming

Boreal                                                          22,000                                                     Cold

NE Spruce-Fir                                        17,000                                                      Cool

                                                                        15,000-13,000                                    Warming - Bolling-Allerod Interstadial Warming

Northern Hardwood-Spruce         13,000-12,000                                   Cooling - Younger Dryas Cold Pulse

                                                                   Pleistocene-Holocene Boundary

Appalachian Oak                                 10,000-6,000                                       Warming

Southern Mixed                                     6,000-4,000                                         Warming

Appalachian Oak                                   4,000-present                                    Cooling

Source: Adapted from Litwin et al., 2004.     

Climate is continuing to change in Shenandoah National Park. Average temperatures in the SNP are expected to shift upwards any where from 1.7°F to 12.7°F depending on the climate model, assumptions, and baseline years. By the end of the century, temperatures are likely to exceed the upper end of the historical range of the last 45,000 years.
 
In addition to temperature changes, annual precipitation is expected to increase from 1.5 to 8.5 inches by the end of the century. The future climate at the Park, therefore, is likely to include on average milder winters with fewer frost days, hotter summers, and wetter and cloudier conditions.
 
As a result of these climate changes, Shenandoah National Park is likely to evolve from an Appalachian Oak biome to a Southern Mixed Pine biome.
 
This may mean a loss of species such as maple, eastern hemlock, northern red oaks, yellow poplar, beech, and other northern hardwoods, and an increase in hickory, sweet gum, shortleaf and longleaf pine, loblolly pine, various elms, and southern oaks (National Park Service, 2015b).            
​

                                        Appalachian Oak Forests                                                                    Southeastern Mixed Pine Forests
                                        Source: Wikipedia                                                                                    Source: Wikipedia
 
But climate changes are occurring faster today than they did 45,000 years ago. Temperature and precipitation changes that occurred in the past over thousands of years are occurring today in less than 100 years. In the short term this is likely to:

• increase stressors affecting current biomes, such as insect pests, invasive plant species, and pathogens (many of which are already occurring in the Park),
• cause shifts in the seasonal timing of natural events, warmer water and increased flows in Shenandoah streams, and
• change the ranges for Shenandoah plants and animals.

 
For example, native brook trout are a cold-water fish. Park officials have measured warmer stream temperatures in recent years, which could put the brook trout under stress and may ultimately eliminate or greatly reduce their numbers in the Park (Saunders, et al., 2010; Flebbe, et al., 2006; National Park Service, 2017a). Another animal that may become a climate change casualty is the Shenandoah salamander, an endangered species that is found nowhere else on the planet.
 
About a quarter of bird species and 10 percent of the mammals in the Park will likely shift their ranges into and out of the park as the result of either direct or indirect climate effects (National Park Service, 2019d; Wu, et al., 2018; Burns, et al., 2003). Some mammal species, such as the red squirrel and the southern red-back vole, are particularly sensitive to climatic conditions and may be lost to the Park (Burns, et al., 2003). Species reshuffling, however, may result in a net gain to the Park, as more species move into and colonize the Park than move out.
 
So when you next consider the Good Ole Days, think longer term, both in terms of the past and the future.
 
References
 
Burns, C. E., Johnston, K. M., & Schmitz, O. J. (2003). Global climate change and mammalian species diversity in U.S. national parks. Proceedings of the National Academy of Sciences, 100(20), 11474–11477. DOI: 10.1073/pnas.1635115100
 
Flebbe, P. A., Roghair, L. D., & Bruggink, J. L. (2006). Spatial Modeling to Project Southern Appalachian Trout Distribution in a Warmer Climate. Transactions of the American Fisheries Society, 135(5), 1371–1382. DOI:10.1577/T05-217.1
 
Litwin, R. J., Morgan, B., Eaton, L. S., & Wieczorek, G. (2004). Assessment of Late Pleistocene to recent climate-induced vegetation changes in and near Shenandoah National Park. USGS OFR 2004-1351. DOI: 10.3133/ofr20041351
 
National Park Service (2019d). Projected Effects of Climate Change on Birds in U.S. National Parks, Briefing Note. Retrieved from https://www.nps.gov/subjects/climatechange/upload/01-NPS_Overall_Project_Brief_508Compliant.pdf
 
National Park Service. (2017a). Climate Change Impacts at Shenandoah National Park. Retrieved from https://www.nps.gov/shen/learn/nature/climatechange.htm
 
National Park Service. (2015b). Climate, Trees, Pests, and Weeds: Change, Uncertainty, and Biotic Stressors at Shenandoah National Park. Project Brief.
 
Saunders, S., Easley, T., & Spencer, T. (2010). Virginia Special Places in Peril: Jamestown, Chincoteague, and Shenandoah Threatened by Climate Disruption. The Rocky Mountain Climate Organization and NRDC. Retrieved from http://www.rockymountainclimate.org/images/VA_SpecialPlaces.pdf
 
Wu, J.X., et al. (2018). Projected avifaunal response to climate change across the US National Park System. Plos One, 13(3): e0190557. DOI: 10.1371/journal.pone.0190557.
​​

By Eva Frederick, Science Magazine  Oct. 10, 2019 , 12:15 PM
State birds can be a source of tremendous local pride—but as the climate warms, at least eight state birds may no longer call their native state home, The New York Times reports. In a new study, National Audubon Society scientists mapped the ranges of 604 North American bird species and used climate models to predict how the their habitats would change. Many species, the team concluded, would likely end up moving north to find their ideal habitats. For example, if temperatures rise 3°C above preindustrial levels—a plausible outcome, according to scientists—the common loon, Minnesota’s state bird, might bypass the state entirely and fly farther north to breed and hunt for food. Unfortunately, moving north might not be enough for many species—out of all types of bird studied, two-thirds face increasing risk of extinction as temperatures rise.

Article from NPR Website
October 16, 2019 12:08 PM ET
LAUREN SOMMER/KQED


​Forest biologist Patricia Maloney is raising 10,000 sugar pine seedlings descended from trees that survived California's historic drought.







​When California's historic five-year drought finally relented a few years ago the tally of dead trees in the Sierra Nevada was higher than almost anyone expected: 129 million. Most are still standing, the dry patches dotting the mountainsides.

But some trees did survive the test of heat and drought. Now, scientists are racing to collect them, and other species around the globe, in the hope that these "climate survivors" have a natural advantage that will allow them to better cope with a warming world.

On the north shore of Lake Tahoe, Patricia Maloney, a UC Davis forest and conservation biologist, hunts for these survivors. Most people focus on the dead trees, their brown pine needles obvious against the glittering blue of the lake. But Maloney tends not to notice them. "I look for the good," she says. "Like in people, you look for the good, not the bad. I do the same in forest systems."

Maloney studies sugar pines, a tree John Muir once called the "king" of conifers. "They have these huge, beautiful cones," she says. "They're stunning trees." The sugar pines on these slopes endured some of the worst water stress in the region. Winter snowpack melts fastest on south-facing slopes, leaving the trees with little soil moisture over the summer. That opens the door for the trees' tiny nemesis, which would deal the fatal blow.

Here you have some really good mountain pine beetle galleries," Maloney says, as she peels the bark off a dead sugar pine to show winding channels eaten into the wood. "Like little beetle highways." Pine beetle outbreaks are a normal occurrence in the Sierra. As the beetles try to bore into the bark, pine trees can usually fight them off by spewing a sticky, gummy resin, entrapping the insects. But trees need water to make resin. 

During the drought, "the tank ran dry, and they weren't able to mobilize any sort of resin," Maloney says.
Evolution is a tool that we can bring to bear in helping us get through this future.

But next to this dead tree, Maloney points to one towering above, the same exact species, that has healthy green pine needles. Somehow, it was able to fight the beetles off and survive the drought. As she's found more and more of these survivors, Maloney has studied them, trying to figure out their secret. "What we found is that the ones that were green, like this one, were more water-use efficient than their dead counterparts," she says. In other words, the survivors had an innate ability to do more with less. Individual members of any species can vary dramatically, something tied to genetic differences. That diversity comes in handy when environmental conditions change.

The drought, heat and beetle outbreaks in recent years put extreme pressure on sugar pines, creating a natural experiment that weeded out all but the toughest. "I think what we're seeing is contemporary natural selection," Maloney says. Now, she's trying to ensure their descendants survive.

Inside a greenhouse at her Tahoe City field station, Maloney shows off a sea of young green trees in their own containers. These 10,000 sugar pine seedlings grew from seeds Maloney and her team collected from 100 of the surviving sugar pines. Over the next year, these young trees will be replanted around Lake Tahoe, both on national forest and private land. The hope is the trees, due to their genetics, will be better able to handle a warming climate, more extreme droughts and more frequent beetle outbreaks. "These survivors matter," Maloney says. She plans to study the genetics of these trees as they grow, research that could help in other climate-threatened forests.

And Maloney's not alone in searching for species that can handle the warming climate. "Evolution is a tool that we can bring to bear in helping us get through this future," says Steve Palumbi, a biology professor at Stanford University, who has been looking for coral that can handle heat. Coral reefs are bleaching and dying as oceans warm, so Palumbi is growing surviving corals in the hope they can build new reefs full of "super corals." Reefs aren't just tourist attractions, he says. They're also biodiversity hotspots that protect coastlines from flooding by absorbing wave energy. "If it gives us another decade, if it gives us another two generations, that'll be good, we'll take it," he says. "I see these next 80 years as the time where we have to save as much as possible."

But beyond that, it gets trickier, given the rate the climate is changing. "The question in the future is: When the environment changes and it changes really fast, can these populations keep up?" he asks. "How fast can they adapt? How much help will they give us in keeping those ecosystems going?" Ultimately, Palumbi says, the best solution for these species is for humans to curb emissions of heat-trapping gases. In the meantime, scientists are trying to buy them a little more time.
© 2019 npr
​See also: The Tree Canopy Biota video