Tag: nature

Hybrids May Offer a Second Chance to Chestnuts and Elms

He walked through the garden when he noticed an odd canker on the chestnut tree. While this could have been a scene from the recent past, chestnut blight was discovered in the New York Botanical Gardens in 1904. Dutch elm disease was first identified in the U. S. in 1930 and was likely introduced into Europe from Asia during World War I. Both of these have resulted in significant losses in both of these species of trees. However, in recent years, through a combination of identifying resistant individuals and breeding programs, there have been efforts to give both species a second chance.

Savannah Ferreira, the Forest Health Specialist for the Vermont Department of Forests, Parks, and Recreation, stated that both American Chestnuts (Castanea Dentata) and American elms (Ulmus americana) are “severely impacted by the diseases.” In their native ranges, they have provided food, timber, habitat, and erosion control. Chestnuts were one of the most important food-producing trees for both large and small wildlife. Ferreira said that as chestnuts became less prevalent, they were replaced by other (and sometimes invasive species).

Both chestnut blight and Dutch elm disease are caused by fungi. Chestnut blight is caused the fungus Cryphonectrea parasitica and was accidentally imported from Asia. Ferreira said that the spores find a wound in the bark and grow through the cambium layer, where tree growth takes place, preventing water and nutrients from reaching the upper part of the tree and subsequently killing it. The symptoms include reddish brown patches that develop into swollen or cracked cankers, which kill twigs, limbs and eventually the tree. Yellow or orange masses of spores ooze from fruiting bodies on or around the cankers. It is spread by the wind, splashing rain, people transporting infested wood, animals, and can also persist in the root system for years. Ferreira said that the fastest form of transmission was typically through root grafts, with wind as the next fastest. She said animals can pick up spores, but they would have to carry it to another chestnut tree.

Dutch elm disease is caused by three species of fungus in the genus Ophistoma. It is spread by the European elm bark beetle and the American elm bark beetle. The beetles seek out dead or weakened trees and excavate a gallery in between the bark and the wood where they lay their eggs. If the fungus is present, adult beetles can carry it on their bodies when they emerge. When they feed on the leaves of the tree, some of the fungus can get dislodged. It colonizes the xylem, which is an inner layer of the tree’s wood, and as with chestnut blight, prevents water and nutrients from reaching the tree, thereby killing the tree. The leaves wilt and turn a dull green to yellow or brown and drop early. Ferreira noted that elms coevolved with the American elm bark beetle and could tolerate them more easily than the European variety. In addition, she also said that elms were not the only host for them either, which put less pressure on the trees. In addition to natural resistance, predation can also play a role in keeping pests in check. Ferriera said that research may not be available, but many beetles are preyed on by woodpeckers as well as parasitic wasps and flies.

In recent years, there have been efforts to bring both species back through a variety of breeding programs. The American Chestnut Foundation (TACF) crosses the American chestnut with the Chinese chestnut (Castanea mallisimo) for resistance to chestnut blight. Chinese chestnuts coevolved with the disease and are therefore, more easily able to tolerate it. Deni Ranguelova, the New England Regional Science Coordinator for TACF, acknowledged that the original plan wasn’t “as evolved” as it could have been, but said the main focus was on tolerance of the disease rather than resistance. In addition to chestnut blight, the foundation also breeds for tolerance to Phytopthora root rot, which is caused by the soil pathogen P. cinnamomi. PRR, as it is known, attacks the root system below ground, though it is primarily found in the southern part of the country. The foundation uses computer models with DNA profiles along with field measured responses to the diseases to predict which trees will be the most tolerant of the diseases. The top 10% are planted in seed orchards with the remaining 90% planted in offspring test sites. The trees are then evaluated in a variety of environments for blight resistance and also used to update computer models for selection accuracy. The hybrids are then backcrossed with pure American chestnuts with the goal of disease tolerance as well as maintaining 70% American ancestry.

Ranguelova said that in addition to the seed orchards and evaluation sites, some trees have been replanted in the wild, but these are not as closely monitored. She said some Japanese chestnuts have been used in the crosses, but that Chinese chestnuts were more cold tolerant and better suited to the North American climate. She said the foundation only breeds chestnut trees, but noted that all diseases “were important” and she would “volunteer for other organizations.” She also said that the hybrids were still considered American chestnuts, officially designated as Castanea dentata, and the goal was to restore the trees to their native range and fulfill their ecological role.

Regarding TACF’s work, Ferreira said that hybrids would “hopefully” allow the return of chestnuts to their native ecosystems. She noted that there are resistant elms for sale in some nurseries, which are less susceptible, but are not immune. She said scientists are breeding both resistant elms as well as nonresistant ones with other species of elms. She also said that there are “aspects” of hybrids that may fulfill certain ecological roles, but only the American chestnut can fulfill 100% of its ecological role and the same hold true for the American elm. American chestnuts can reach heights of 60-100 feet. By comparison, Chinese chestnuts generally only grow to about 30 feet.

Unlike pests such as the emerald ash borer and the spotted lantern fly, chestnut blight and Dutch elm disease, have been in North America for over 100 or nearly 100 years, respectively. So, can something be learned from “established” diseases in order to address more recent invasive pests? Ferreira said yes and emphasized the importance of diversification in urban and forest landscapes. She said that when the focus is only on one genus or species, there is an “increased risk of large scale impacts by invasive species.” Ferreira also noted that the “gears were shifting from reporting diseased trees to non-diseased or potentially resistant trees.” She recommended treesnap.org as a place where such trees could be reported in order to further efforts of breeding resistant individuals.

Invasive pests and diseases have been a serious threat for a long time. However, an understanding of the importance of biodiversity as well as how species can evolve to combat pests can go a long way to giving some species a second chance. For related topics, see my articles on Asian jumping worms from August of 2024, Asian carp from February of 2023, the spotted lanternfly from November of 2021 and endangered plants from May of 2023.

Being Green: Grasses and Groundcovers Create Important Habitat

The butterfly flew from one lawn to the next looking for food, but all there was only grass with nothing else. Finally, she found some low growing flowering sedges. There were other butterflies as well as bees here, too, and a bit farther off, a child played fetch with a dog. Lawns are one of the most common sights and for a groundcover or a place to kick a ball around, they have their uses. However, most traditional turf grasses aren’t native to North America, are frequently invasive, and require a large amount of care. Nevertheless, there are a large number of native grasses which provide important habitat for a large variety of species, generally require less mowing and no fertilizer, and still be a place for people as well.

Grasses:

Pennsylvania Sedge (Carex pennsylvania)

This grass reaches about 9 inches tall, requires well drained dry soil, and tolerates shade. It stops growing by early summer and generally only needs to be mowed once to twice a year to stay 4-5 inches. It is native to New York and Maine south to Virginia, the Carolinas, and Tennessee, and west to Washington, California, and New Mexico.

Plantain sedge (Carex plantaginea)

This grass grows to 12 inches, needs moist soil, and shade to partial shade. It has bright green leaves and small yellow flowers in early spring. It is native to New Brunswick and southern Quebec to southern Indiana, Kentucky, New Jersey, Maryland, and northern Georgia.

Poverty oat grass (Danthonia spicata)

This grass reaches 8-16 inches and also only needs mowing once to twice a year. It is native to most of the United States and needs well drained or seasonally moist soils and full sun, though it will tolerate dry and nutrient poor soils. Flattened oat grass (Danthonia compressa) is native to the eastern U.S. and California oat grass (Danthonia Californica) is native west of the Rockies.

Groundcovers:

Common strawberry (Fragaria virginiana)

Strawberries grow 3 to 6 inches, have small white flowers in May and fruit in June. They are native throughout North America. After fruiting they send out runners, and so spread easily and are an excellent groundcover. They attract bees, butterflies, and birds (and, of course, people too!)

Moss phlox (Phlox subulata)

This flower grows 2 to 6 inches tall, needs well drained soil and has pink flowers from April to May. It is native to southern New York to southern Michigan and south to North Carolina and Tennessee.

“Traditional” lawns are essentially a monoculture and provide little in the way of biodiversity. Nevertheless, there are larger spaces where grasses and groundcovers are the best option for that particular area. For such places, native grasses and groundcovers can provide both food, nesting, and overwintering sites as well as a green place for people, pets, and pollinators.

As always, not using pesticides or fertilizers is also important in creating habitat for birds, bees, and butterflies. For other resources, go to plant finder on the National Wildlife Federation (www.nwf.org), put in your zip code and the site will provide a list of all plants native to your area. For my other articles on wildlife gardening, including plants for small spaces, shade tolerant plants, and food plants for both people and wildlife see April 2019, May 2020, May 2021, July 2022, June 2023, and June 2024.

The Christmas Bird Count Tracks Population Changes

Is that really a bluebird in December? Just an aberration or part of a larger pattern?  Wouldn’t it be fun to know what other people are seeing and be part of an important conservation effort a as well? The Christmas Bird Count (CBC) is one way people can make their sightings official and track both changing populations and migrations. It runs from December 14 to January 5 and 2023 will be the 124th year. It is one of the longest running wildlife censuses in the world. Jillian Liner, the Director of Conservation for Audubon VT, said that it shows how birds are doing and where they are. She also said that the length and scope of it are two of the most important aspects of the CBC.   

Liner said that CBC data has been noting some recent trends in migration patterns and behavior. One example she gave is that bluebirds have been either staying longer into the winter or not migrating at all due to increasingly milder winters. While December may seem like an odd time to do a bird count, Liner said that it is a time of year when birds are mostly “settled” and the CBC can capture birds in a largely permanent location. 

If people are interested in participating, they can go onto the Audubon website and get contact information for their local area. Liner said however, that people can also call the local Audubon chapters. Participants go out in 15 mile wide circles and they record their sightings on paper of both species and total numbers of birds seen. The circles are run by a compiler who organizes volunteers and submits the data. Liner also said compilers will usually pair new birders with more experienced birders as well.

Prior to the twentieth century, hunters held a Christmas “side hunt” in which they competed over who killed the most birds. As concerns over declining populations grew, scientists looked for ways to encourage conservation. Ornithologist Frank Chapman proposed a Christmas bird count and the first one was held in 1900. It included 27 birders in locations from Toronto to California and tallied 90 species. By comparison, according to http://www.audubon.org, last year’s CBC included 79,005 observers with a total of 40 million birds counted from 2500 different species.

Counting birds and other wildlife shows population changes and can also provide data as to what conservation measures might be needed. However, there are far more birds than scientists can count on their own and having volunteers gives a more accurate data set. In addition, it is a chance to connect to the larger world and maybe have a new and fun experience. (For more on community science and wildlife in the winter, see July 2023 and February 2021 articles).  

 

Citizen Science Offers a Chance for Exploration

Was that the lost satellite? In 2018, a citizen scientist looked up at the sky and contacted NASA to say he believed he had found the missing IMAGE satellite, which they had lost contact with in December of 2005. According to science.nasa.gov, NASA confirmed the ID and verified it was in fact the missing satellite. While not all citizen scientists will achieve instant fame, they play an important role in research. All over the world, people go out and record sightings and their data is uploaded which helps scientists track migrations, rare species, and find invasive species.   This can then be used for directing public policy and protecting important habitat.   

Dr. Tina B. Phillips, Assistant Director for the Center for Engagement in Science and Nature at Cornell University, said that citizen science advances scientific knowledge on “large geographic scales” and can give scientist the “big picture” on species ranges and well as detecting invasives. She also said participants gain knowledge and acquire new skills. In addition, Phillips also noted citizen scientists can help their own communities by collecting air and water samples, which can then be used to make changes in regulations and living conditions.

Phillips also stated that scientists are limited by the regions they live in whereas citizen scientists can be the “eyes and ears” collecting far more data than scientists would be able to do on their own. Dena Podrebarac, the Milkweed Coordinator for Monarch Watch, concurred saying citizen scientists are able provide more research than a much smaller number of scientists would be able to do. She also noted that there is a move to change the name to “community science.” Podrebarac also stated that citizen or community science can further knowledge, raise awareness, and create education opportunities. Phillips noted some good projects included several of the ones done through Cornell University, such as E-bird. She also recommended Galaxy Zoo and Scistarter.org. In addition, the National Wildlife Federation and citizenscience.gov also have listings of several citizen science projects.

E-bird-This is run through Cornell University and people can share sightings, update lists of all birds they’ve observed, and archive photos and sounds. 

Monarch Watch-This is done through the University of Kansas.   People tag monarchs as well as record tag number, date, and location of other butterflies.  monarch@ku.edu.

Monarch Calendar-People record the number of monarchs they see each day during the migration periods. In the South this is done from Aug. 1 to Sept 25 and in the North it is done from July 15-Aug. 20.  

Nonindigenous Aquatic Species Program-People verify the occurrence and distribution of nonnative animal and plant species.   Observations can be made through an online reporting system.   http://nas.er.us.gs.gov.

Citizen scientists play an important role in their communities and in the world. There are far more citizens in many more places than there are scientists and that is what allows citizen scientists to collect much more data. In addition, it gives people the opportunity to get outdoors, learn about their ecological neighborhood, and cultivate the next generation of scientists.