Native fungus suggested as another tool for restoring ghostly whitebark pine forests

Siberian slippery jack is a native fungus that may help in the effort to restore whitebark pine forests.
Credit: Cathy Cripps

Cathy Cripps doesn't seem to worry about the grizzly bears and black bears that watch her work, but she is concerned about the ghosts and skeletons she encounters.

The ghosts are whitebark pine forests that have been devastated by mountain pine beetles and white pine blister rust, said the Montana State University scientist who studies fungi that grow in extreme environments. The skeletons are dead trees that no longer shade snow or produce pine cones. The round purple pine cones hold the seeds that feed bears, red squirrels and Clark's nutcracker birds. Shade at the top of watersheds keeps snow from melting too fast in the spring, preventing trout streams from drying up too early in the summer.

Fortunately, she has found hope in a native fungus called Siberian slippery jack, or Suillus sibiricus, said Cripps, a mycologist in MSU's Department of Plant Sciences and Plant Pathology.

Cripps conducted a three-year study in collaboration with Waterton Lakes National Park in Canada that showed a 10 to 15 percent increase in the survival rate of whitebark pine seedlings when Siberian slippery jack spores are injected into the soil around them. The injection takes place in nurseries before the seedlings are transplanted in the mountains.

That increase is significant and good news for those trying to reinstate whitebark pine trees to the north-central Rocky Mountains and Pacific Northwest, Cripps said. The whitebark pine is a keystone species that grows at high elevations where other trees cannot, but it has been declared an endangered species in Canada and awaits the designation in the United States.

"That (jump in survival rates) might not sound like a big difference, but a small amount is a big deal considering the labor-intensive process," Cripps said.

Cyndi Smith, scientist emeritus at Waterton, said "The positive results have encouraged Waterton Lakes National Park to continue inoculating both whitebark and limber pine seedlings, to give them the best opportunity we can to establish and survive to maturity."

Participants in the research project, in addition to Cripps' and Smith's teams, were the U.S. Forest Service, National Park Service and volunteers from the United States and Canada.

Explaining how the collaboration began, Smith said, "Cathy gave a presentation on some of her Yellowstone work at the annual science meeting of the Whitebark Pine Ecosystem Foundation in Hailey, Idaho, in 2006. I was really taken with the idea that the ecosystem may have lost the beneficial fungi because our forests have been dead and dying for so long and that perhaps there was a way to reverse that trend so I approached Cathy with the idea.

"I'm a big believer in collaboration, whether locally or internationally, but certainly working with someone of Cathy's academic stature has been very helpful when I have applied for funding for whitebark and limber pine projects," Smith said, adding that, "Cathy's enthusiasm is very infectious, and it is a delight to work with her."

To carry out the research project, the participants placed cages around whitebark pine trees to collect pine cones without interference from wildlife. Then they tested the cones to see if they were resistant to white pine blister rust, removed seeds by hand from the resistant cones, grew the seeds into seedlings and shipped them to the nursery in Glacier National Park.

Cripps and former graduate student Erin Lonergan drove to Waterton Lakes 

National Park and throughout the Greater Yellowstone area, hiked to the tops of mountains and collected the Siberian slippery jack and other fungi from whitebark pine forests. Then they returned to MSU where they used a coffee grinder to process the spongy outer layer of the fungi. They added water to create a spore slurry, stored the mixture at MSU and later injected about 3 million spores into the soil around each seedling temporarily housed at the Glacier National Park nursery.

A few months later, volunteers planted more than 1,000 seedlings into MSU's test plots. Most of those test plots were located in Waterton, while others were in the neighboring Glacier National Park. The two parks together comprise Waterton-Glacier International Peace Park.

Two years into the study, Lonergan, Cripps and Smith reported success in the journal, American Forests. One year later, they announced their final results in the spring/summer 2014 issue of Nutcracker Notes, a small journal hosted by the Whitebark Pine Ecosystem Foundation.

"We wanted to get the word out that results after three years showed that inoculation with these native fungi significantly improved the survival of rust resistant seedlings, especially when inoculated seedlings were planted in burned areas near shelter objects such as stumps and logs," Cripps said.

High nitrogen fertilizations and fungicides prevent the inoculations from working, Cripps said. The age of the seedlings is important because they need to grow plenty of side roots before being inoculated.

When successful, the injected fungi slip like tiny socks over the ends of every root of the whitebark pine seedling and form a relationship that benefits both the tree and the fungi, Cripps said. The fungi help the seedling take in more nutrients and water from the soil. The tree produces the sugars that feed the fungi.

"Instead of being bad guys, these fungi are beneficial," Cripps said of the Siberian slippery jack. "They help plants take up nitrogen and phosphorus from the soil. That's a big deal."

Her study is one of many research projects involving whitebark pine forests, but it's unique because it focuses on beneficial native fungi, Cripps said. She added that land managers might want to incorporate MSU's findings into their overall strategy for restoring whitebark pine forests. She noted that large-scale inoculations are already planned for nurseries in Canada. She said inoculating beneficial fungi into nursery stock is common in Europe.

"As we work to save the vital whitebark pine from disappearing from the landscape, it is essential to use all available tools," Cripps said. "Ectomycorrhizal fungi are an integral part of forest integrity, ecology and health. Showing respect for these mighty microbes might just mean the difference between the restoration and death of a forest."

"Ectomycorrhizal fungi" refers to beneficial fungi that form a symbiotic relationship with the roots of trees. Siberian slippery jack is one of those fungi, and it only associates with five-needle pines. White pine blister rust is another type of fungus, one of the "bad guys."

Source: Montana State University

Primates indispensable for regeneration of tropical forests

Moustached tamarins (Saguinus mystax) contribute crucially to the seed dispersal of the neotropical tree Parkia panurensis. Credit: Julia Diegmann

Primatologist and plant geneticists have studied the dispersal of tree seeds by New World primates.

Primates can influence seed dispersal and spatial genetic kinship structure of plants that serve as their food source. This is the result of a cooperation project of behavioral ecologist Eckhard W. Heymann from the German Primate Center (DPZ) with plant geneticists Birgit Ziegenhagen and Ronald Bialozyt from the Philipps-University Marburg. This study was funded by the German Research Foundation.

At the DPZ-field station Estación Biológica Quebrada Blanco in the Peruvian Amazonian lowlands, scientists studied how feeding, sleeping, and ranging habits of two species of New World monkeys affect the dispersal of the neotropical legume tree Parkia panurensis. For this, the researchers observed a group of Brown-mantled tamarins (Saguinus nigrifrons) and Moustached tamarins (Saguinus mystax), who jointly moved through home ranges in search of edible plants which included Parkia trees.

Fruits from these trees are pods that contain 16 to 23 seeds, each of which is surrounded by edible gum. The monkeys feed on the gum content of the pods and at the same time swallow the Parkia seeds which are later defecated intact in a different area.

During behavioral observations, researchers recorded the food intake of tamarins as well as the location of the Parkia trees that they visited. In addition, they collected faecal samples of the tamarins that contained seeds. "With the help of genetic analyses of the DNA found in the seed coat, which is of maternal origin, we could make an exact assignment of the corresponding "mother tree" for the seeds," says Eckhard W. Heymann from the DPZ. "This allowed us to determine how far Parkia seeds were dispersed by the monkeys."

In order to analyze the effect of seed dispersal by monkeys on a spatial genetic level, the scientists examined three different developmental stages of the trees. In addition to the seeds that contain the plant embryo, they collected leaves from young and mature Parkia trees in the home range of tamarins. "With the help of analysis from microsatellites, short repeated DNA sequences, we were able to identify genetic similarities of individual trees," says Heymann.

The analysis of the spatial genetic structure of the Parkia population revealed a significant genetic relationship of the plant embryos and young trees within a radius of 300 meters, which coincides with the distance within which most seeds are dispersed by the tamarins. For mature trees, the relationship was reduced to a radius of only up to 100 meters.

"In tropical rain forests, the seeds of 80 to 90 percent of trees and lianas are dispersed by animals. In addition to primates, birds and bats are the major animal groups that are responsible for seed dispersal," says behavioral ecologist Heymann. "For the plants, transport of their seeds is extremely important. As sedentary organisms, this is the only way that their offspring -- the embryos contained in the seeds -- can reach appropriate sites for germination and growth. Furthermore, this reduces the density-dependent mortality which occurs when the seeds fall under the mother plants," says Eckhard W. Heymann. Fruit-eating primates such as tamarins are therefore invaluable to the natural regeneration and diversity of ecosystems in which they live.

Source: German Primate Center

Lemurs: Gardeners of Madagascar rainforest at risk

Onja Razafindratsima, a graduate student at Rice University, observes a lemur in a Madagascar rainforest. Razafindratsima led a three-year study to explore the relationship between lemurs and trees. Lemurs eat the fruit and spread its seeds far from the parent tree to help ensure its survival. Credit: Photo courtesy of Onja Razafindratsima/Rice University

A majority of Madagascar's 101 species of lemurs are threatened with extinction, and that could have serious consequences for the rainforests they call home. A new study by Rice University researchers shows the positive impacts lemurs can have on rainforest tree populations, which raises concerns about the potential impact their disappearance could have on the region's rich biodiversity.

A large proportion of trees in Madagascar's rainforest have fruits eaten by lemurs. Lemurs in turn disperse the seeds of their fruit trees throughout the forest with their scat. Such dispersal can play a crucial role for a tree species' ability to regenerate, but effects are poorly understood, especially when there are multiple dispersers.

For the tree, the evolutionary advantage of having animal-dispersed seeds may be that the seeds land well away from their parent trees where survival is low or that seeds are directed into spots where they are the most likely to sprout and survive.

Amy Dunham, an assistant professor of biosciences, and graduate student Onja Razafindratsima set out to detail the symbiotic relationship between fruit-eating lemurs and the trees that feed them through a three-year study in a rainforest in southeastern Madagascar.

Their data from observations, experiments and mathematical models demonstrate that seeds of a common canopy tree have a 300 percent higher chance of sprouting and becoming a sapling when dispersed by lemurs versus simply falling to the ground. One of the three lemur species is particularly good at dropping seeds in spots that are most advantageous for sprouting and survival. Other lemurs are not so selective, but still benefit the tree by moving seeds away from the parent tree. By acting as forest gardeners, these animals give the tree's population a boost.

The study appeared online in the Ecological Society of America journal Ecology.

As part of the study, the researchers followed the seed-dispersal patterns of three of Madagascar's lemur species: the red-fronted brown lemur, the red-bellied lemur and the southern black-and-white ruffed lemur. That meant tracking and observing groups of lemurs as the animals leaped from tree to tree through the forest, dined in the 65-foot-high canopies and dropped their undigested seeds at ground level.

Razafindratsima led the study as part of a thesis project she expects to complete early next year. She built a team of local researchers near Ranomafana National Park, the home of Centre ValBio, a research station founded by Dunham's former Ph.D. adviser, primatologist Patricia Wright.

"We have a team of up to 10 local villagers who are trained to do research," said Razafindratsima, a native of Madagascar. "Their exceptional knowledge of the forest is very important to us when we're trying to track lemurs and identify seeds and seedlings in a forest with over 300 species of trees."

The research team tracked 24 groups of lemurs over a year without the benefit of radio collars, said Razafindratsima, who keeps in touch with her team via phone and Skype when she's at Rice. She said the study sites were as close as a short hike from Centre ValBio and as far as a two-day trek through steep terrain that entailed camping overnight.

In addition to tracking lemurs and their dispersed seeds, the research team spent three years carrying out experiments on seed sprouting and survival. They found that dispersal by lemurs dramatically increased the odds that seeds would take root and survive. In particular, the red-fronted brown lemurs tended to drop seeds away from their parent trees and in places where there were gaps in the canopy. This gave individual seeds the best shot at taking root.

Dunham said trees benefit from the wide dispersal of their seeds, and for some species in Madagascar, lemurs are the primary or only animal that can distribute those seeds. As the largest fruit-eaters in the system, these lemurs swallow seeds that may be too large for other fruit-eating animals, such as birds or bats.

"Seeds away from the parent tree survive better because there's less competition among seedlings," Razafindratsima said. "If they're close by the parent, they may also share the same natural enemies, like soil pathogens and seed predators, so there's higher mortality."

Trees that lose their dispersers will simply drop their seeds to the ground beneath their canopies, where chances of survival are slim, Dunham said. "Lemurs fill an important role as the gardeners for these trees. By ensuring that some seeds land in spots suitable for germination and survival, they increase the ability of these trees to replace themselves"

Dunham hopes the study will contribute to growing efforts to protect lemurs, and therefore the rainforest, which has been impacted in recent years by economic and political instability.

She noted grassroots efforts within Madagascar led to the first World Lemur Festival in late October to celebrate and protect the animals and their habitats in Madagascar.

"What got us interested is that frugivorous lemur populations are declining across the island, and we know very little about how these seed dispersers actually affect tree populations," she said. "Once we understand that better, maybe we'll have a better idea of how the community might change if the lemurs disappear.

"If some species suddenly lose their dispersers, but others dispersed by birds or the wind are doing fine, it may change population trajectories and alter which tree species are dominant in a community. To understand what happens when these species are lost, we need to understand their role in the ecosystem," she said.

Source: Rice University

Potential biological control for avocado-ravaging disease

University of Florida scientists think they’ve found the first potential biological control strategy against laurel wilt, a disease that threatens Florida’s avocado industry. The redbay ambrosia beetle, see here, bores holes into avocado trees, bringing the disease that causes laurel wilt. Credit: Lyle Buss, UF/IFAS

University of Florida scientists believe they've found what could be the first biological control strategy against laurel wilt, a disease that threatens the state's $54 million-a-year avocado industry.

Red ambrosia beetles bore holes into healthy avocado trees, bringing with them the pathogen that causes laurel wilt. Growers control the beetles that carry and spread laurel wilt by spraying insecticides on the trees, said Daniel Carrillo, an entomology research assistant professor at the Tropical Research and Education Center in Homestead.

But a team of researchers from the Tropical REC and the Indian River Research and Education Center in Fort Pierce have identified a potential biological control to use against redbay ambrosia beetles that could help growers use less insecticide.

First, they exposed beetles to three commercially available fungi, and all of the beetles died. Then they sprayed the fungi on avocado tree trunks, and beetles got infected while boring into the trunk. About 75 percent of those beetles died, said Carrillo, an Institute of Food and Agricultural Sciences faculty member.

Ideally, the fungal treatments could prevent beetles from boring into the trees, eliminating the risk that the pathogen would enter the trees, the study said. But tests showed female beetles bored into the trees and built tunnels regardless of the treatment. Still, researchers say their treatment can prevent the female beetles from laying eggs.

UF/IFAS scientists don't know yet how much less chemical spray will be needed to control the redbay ambrosia beetle. But Carrillo sees this study as the first step toward controlling the beetle in a sustainable way.

"When you want to manage a pest, you want an integrated pest management approach," Carrillo said. "This provides an alternative that we would use in combination with chemical control."

The redbay ambrosia beetle -- native to India, Japan, Myanmar and Taiwan -- was first detected in 2002 in southeast Georgia. It was presumably introduced in wood crates and pallets, and its rapid spread has killed 6,000 avocado trees in Florida, or about 1 percent of the 655,000 commercial trees in Florida. The beetle was first discovered in South Florida in 2010.

Most American-grown avocados come from California, with the rest coming from Florida and Hawaii. The domestic avocado market is worth $429 million, according to Edward Evans, a UF associate professor of food and resource economics, also at the Tropical REC. Florida's avocados are valued at about $23 million, or about 5 percent of the national market.

The redbay ambrosia beetle is not an issue with California avocados, so the new tactic found by Florida scientists wouldn't apply to this pest in the Golden State, said Mark Hoddle, a biological control Extension specialist with the University of California-Riverside. Hoddle studies biological pest control for California avocados. Scientists there are exploring ways to control a different ambrosia beetle, he said, and bug-killing fungi may be useful for the new California pest.

More than 95 percent of Florida's commercial avocados grow in Miami-Dade County, although many Floridians have avocado trees in their yard.
The redbay ambrosia beetle feeds and reproduces on a very wide variety of host plants, native oaks, sycamores, and of course it is very detrimental to avocados.

Source:University of Florida Institute of Food and Agricultural Sciences

Tree diseases can help forests

A healthy seedling of the tree Castilla elastica is on the left, while a dying seedling, attacked by a plant pathogen, is on the right. A study in the Journal of Ecology by University of Utah biologists shows that such tree diseases, while killing individual seedlings, can increase forest biodiversity. Credit: Erin Spear, University of Utah.

Plant diseases attack trees and crops and can hurt lumber and food production, but University of Utah biologists found that pathogens that kill tree seedlings actually can make forests more diverse.

While low rainfall has been blamed for a lack of drought-sensitive trees near the Pacific side of the Panama Canal, the new study answers a mystery about what keeps drought-tolerant trees from that area from living along the wetter Caribbean side of the canal. The answer: disease-causing plant pathogens, the researchers report in their study, published online Wednesday, Nov. 12 by the Journal of Ecology.

"Because seedlings of disease-sensitive tree species can't survive in the wetter forests and drought-sensitive tree species cannot survive in the drier forests, different tree species inhabit the wetter and drier forests even though they are only 30 miles apart" in Panama, says Phyllis Coley, a senior author of the study and a distinguished professor of biology.
In other words, tree pathogens contribute to the staggering diversity of trees in Panama's tropical forests, she adds.

The study's first author, biology doctoral student Erin Spear, says that is important because "conservation planning and predictions about how tree species distributions may shift with climate change require an understanding of the factors currently influencing where species can and cannot survive."

That is particularly important in tropical forests and other forests that are under elevated threat of deforestation.

Funding for the study came from Sigma Xi -- The Scientific Research Society, the Smithsonian Institution and the National Science Foundation.

Of Forests and Pathogens

Tropical forests are threatened, and dry tropical forests are even more threatened because sunnier, drier climates are better for growing crops and are favored by people. Some 90 percent of Panama's residents live on the nation's drier Pacific slope.

Forests are essential for feeding and sheltering animals, providing important medicines, storing carbon and water, and reducing erosion by holding soil in place. These functions are influenced by different species inhabiting a forest, so it is essential to understand why certain tree species can survive in certain areas but not others.

Panama's forests also are important economically because tree roots limit how much soil erodes into the Panama Canal, ensuring that huge container ships can pass. Researchers also believe the forests help maintain water levels in the canal because forest soil stores water, slowly releasing it into streams feeding the canal during the dry season.

Diversity is high in tropical forests. A 930-square-mile area bordering the Panama Canal has more than 800 tree species. By comparison, about half the state of Rhode Island -- or some 610 square miles -- is forested, and that area has only 51 tree species.

Part of the reason Panama's forests have more species is because the Pacific end of the canal receives less annual rainfall -- about 5.9 feet -- than the Caribbean end, where 9.8 feet of rain falls annually.

"While there is considerable evidence that less rain in the drier, Pacific forests means that drought-sensitive tree species can't survive there, it has been unclear what prevents the drought-tolerant species of the drier forests from living in the wetter forests," says University of Utah biology professor Tom Kursar, the study's other senior author. "Our study tackled that unanswered question."

So Spear braved mud, rain, insects and snakes to monitor seedlings of a variety of tree species in the wetter and drier forests of central Panama for pathogen-caused damage and death. Plant pathogens that make plants sick include bacteria, viruses and fungi.

Spear says the researchers' findings suggest that "all seedlings are at a greater risk of being injured and killed by pathogens in the wetter forests than in the drier forests." This could be because the damp environment of the wetter forests helps pathogens survive, and more rainfall helps pathogens move from one seedling to another.

But that's only half the story. Coley says that their study indicates "pathogens are implicated in the absence of the dry-forest tree species from the wetter forests, where they might otherwise be able to live. That is because dry-forest tree species are more likely to die from pathogen attack than wet-forest species."

Diagnosing Sick Seedlings

Spear collected the seeds for the study by hiking for miles, kayaking in the canal to collect fruit from overhanging branches, and even riding a crane-carried gondola more than 100 feet upward into the forest canopy.

She conducted the study at two forest sites in central Panama: one at the large Metropolitan Natural Park in Panama City on the drier Pacific side, and one on private property in the Santa Rita Ridge area on the wetter Caribbean side. She planted "gardens" of tree seeds -- including species typical of wetter and drier forests -- in 30 locations at each site. More than 1,000 seeds were planted; 725 of them sprouted.

Once the seeds were planted, the researchers covered them with wire mesh to protect the seeds and seedlings from being crushed by tree branches or eaten by animals.

Spear visited both sites weekly and took notes on the 725 seedlings. Weekly visits were essential because, diseased seedlings can be dead and decomposing within days.

"We monitored when the seeds germinated, the occurrence of and date when symptoms of pathogen attack were observed, if and when a seedling died, and we ascribed a cause of death," Spear says. Pathogen symptoms included patches of black, dead tissue in the leaves or stem. "In some cases, we could actually see the pathogen growing on the seedling," she says.

Of the 725 seedlings that germinated, 38 percent suffered pathogen-caused damage, including 11 percent of seedlings killed by pathogens.

Compared with seedlings in the drier forest, seedlings in the wetter forest were 74 percent more likely to suffer pathogen-caused damage and 65 percent more likely to be killed by pathogens.

"But what was really striking was that pathogen-caused damage was five times more likely to be lethal for seedlings of dry-forest species than for wet-forest species," suggesting dry- and wet-forest species differ in their ability to halt or slow infection, Spear says.

The researchers next plan to identify specific fungi, bacteria and other pathogens and whether they differ in wetter and drier forests.

During her study at the drier park site in Panama City, Spear discussed her research with tourists and other park visitors.

"I'd emerge from the tangles of vines sweaty, muddy and generally disheveled and people couldn't help but ask what I was doing," Spear recalls. "It was heartening to hear how the forest had touched these very different people."

A brief time-lapse video of a seedling dying from pathogen attack during a period of several days can be seen at: http://vimeo.com/58026978 Video by Erin Spear, University of Utah.


Source: University of Utah

If trees could talk: Forest research network reveals global change effects

In addition to identifying, mapping, measuring and monitoring trees in the CTFS-ForestGEO study plots, researchers describe the relatedness of trees, track flower and seed production, collect insects, survey mammals, quantify carbon stocks and flows within the ecosystem, take soil samples and measure climate variables like rainfall and temperature. The thorough study of these plots provides insights into not only how forests are changing but also why. Credit: Beth King, STRI

Permafrost thaw drives forest loss in Canada, while drought has killed trees in Panama, southern India and Borneo. In the U.S., in Virginia, over-abundant deer eat trees before they reach maturity, while nitrogen pollution has changed soil chemistry in Canada and Panama. Continents apart, these changes have all been documented by the Smithsonian-led Center for Tropical Forest Science-Forest Global Earth Observatory, CTFS-ForestGEO, which released a new report revealing how forests are changing worldwide.

"With 107 collaborators we've published a major overview of what 59 forests in 24 countries, where we monitor nearly 6 million trees teach us about forest responses to global change," said Kristina Anderson-Teixeira, first author of the report and CTFS-ForestGEO and ecosystem ecologist based at the Smithsonian Conservation Biology Institute.

Many of the changes occurring in forests worldwide are attributable to human impacts on climate, atmospheric chemistry, land use and animal populations that are so pervasive as to warrant classification of a new geologic period in Earth's history -- the Anthropocene, the Age of Humans.

Measuring and understanding the effects of all these changes -- collectively termed "global change" -- are easier said than done. Some of the best information about these global-scale changes comes from CTFS-ForestGEO, the only network of standardized forest-monitoring sites that span the globe.

Since the censuses began at the first site on Barro Colorado Island in Panama in 1981, atmospheric carbon dioxide has increased by 16 percent. The forest sites in the network have warmed by an average of over 1 degree F (0.6 degree C) and experienced up to 30 percent changes in precipitation. Landscapes around protected sites experience deforestation.
The plot network now includes forests from Brazil to northern Canada, from Gabon to England and from Papua New Guinea to China.

In addition to identifying, mapping, measuring and monitoring trees, researchers describe the relatedness of trees, track flower and seed production, collect insects, survey mammals, quantify carbon stocks and flows within the ecosystem, take soil samples and measure climate variables like rainfall and temperature. The thorough study of these plots provides insights into not only how forests are changing but also why.

Climate change scenarios predict that most of these sites will face warmer and often drier conditions in the future -- some experiencing novel climates with no modern analogs. Forests are changing more rapidly than expected by chance alone, and shifts in species composition have been associated with environmental change. Biomass increased at many tropical sites across the network.

"It is incredibly rewarding to work with a team of forest scientists from 78 research institutions around the world, including four Smithsonian units" Anderson-Teixeira said. "CTFS-ForestGEO is a pioneer in the kind of collaborative effort it takes to understand how forests worldwide are changing."

"We look forward to using the CTFS-ForestGEO network to continue to understand how and why forests respond to change, and what this means for the climate, biodiversity conservation and human well-being," said Stuart Davies, network director.

Source: Smithsonian Tropical Research Institute

Three new ornamental dogwoods introduced

'Empire', one of the new dogwood varieties, is shown in the photo at 20 years old. 'Empire' features brilliant white bracts and exfoliated bark. Credit: Phillip Wadl

In the nursery and landscape industries, flowering dogwood (Cornus florida), kousa dogwood (Cornus kousa), and their hybrids are the most popular and economically significant members of the genus Cornus. The deciduous trees are highly valued for their spring display of pink, red, or white bracts, brilliant red fall foliage, and exfoliating bark. In the United States alone, retail and wholesale sales of dogwoods account for more than $30 million dollars annually.

In the past, flowering dogwoods were severely affected by dogwood anthracnose and powdery mildew. A program initiated more than 20 years ago at the University of Tennessee resulted in the release of 'Appalachian Spring', the first flowering dogwood cultivar with resistance to dogwood anthracnose, and four powdery mildew resistant cultivars. "We have found that Cornus kousa is more tolerant to anthracnose and powdery mildew than Cornus florida," explained Phillip Wadl, lead author of report published in HortScience. "Hybrids between these two species are generally more vigorous than typical plants of either parent species, and have resistance or tolerance to dogwood anthracnose and powdery mildew."

Wadl and colleagues Mark Windham, Richard Evans, and Robert Trigiano evaluated 400 seedlings of C. kousa for disease resistance and traits such as color, degree of overlap, size of bracts, tree form, and bark and leaf characteristics. The scientists selected three cultivars they named 'Empire', 'Pam's Mountain Bouquet' and 'Red Steeple' for development and eventual release. 'Empire' is a brilliant, white-bracted kousa dogwood that has a columnar form and exfoliating bark. 'Pam's Mountain Bouquet' (patent pending) is a kousa dogwood with a spreading form that features a prolific fused bract display. 'Red Steeple' is a kousa dogwood that features a columnar-shaped canopy with red foliage that fades to green with high temperature and white bracts that have a red tint along the margins.

The authors noted that dogwood anthracnose and powdery mildew were not observed on any of these trees. Analyses showed that 'Empire', 'Pam's Mountain Bouquet', and 'Red Steeple' are genetically distinct from the 26 cultivars and unnamed accessions of Cornus kousa that are maintained in the University of Tennessee's kousa dogwood collection.

The program has applied for a plant patent for 'Pam's Mountain Bouquet'. A limited quantity of budwood has been distributed to wholesale nurseries in Tennessee and Japan, and selected nurseries have been identified to propagate the cultivars.

Source: American Society for Horticultural Science

Colorado's Front Range fire severity not much different than past

A new study indicates present-day forest fires on Colorado's Front Range are not significantly more intense than historical fires. Credit: Glenn Asakawa, University of Colorado

The perception that Colorado's Front Range wildfires are becoming increasingly severe does not hold much water scientifically, according to a massive new study led by the University of Colorado Boulder and Humboldt State University in Arcata, Calif.

The study authors, who looked at 1.3 million acres of ponderosa pine and mixed conifer forest from Teller County west of Colorado Springs through Larimer County west and north of Fort Collins, reconstructed the timing and severity of past fires using fire-scarred trees and tree-ring data going back to the 1600s. Only 16 percent of the study area showed a shift from historically low-severity fires to severe, potential crown fires that can jump from treetop to treetop.

The idea that modern fires are larger and more severe as a result of fire suppression that allowed forest fuels to build up in the past century is still prevalent among some, said CU-Boulder geography Professor Thomas Veblen, a study co-author. "The key point here is that modern fires in these Front Range forests are not radically different from the fire severity of the region prior to any effects of fire suppression," he said.

A paper on the subject was published Sept. 24 in the journal PLOS ONE. The study was led by Associate Professor Rosemary Sherriff of Humboldt State University and involved Research Scientist Tania Schoennagel of CU-Boulder's Institute of Arctic and Alpine Research, CU-Boulder doctoral student Meredith Gartner and Associate Professor Rutherford Platt of Gettysburg College in Gettysburg, Pa.

The study was funded by the National Science Foundation.

"The common assumption is that fires are now more severe and are killing higher percentages of trees," said Sherriff, who completed her doctorate at CU-Boulder under Veblen in 2004. "Our results show that this is not the case on the Front Range except for the lowest elevation forests and woodlands."

One important new finding comes from a comparison of nine large fires that have occurred on the Front Range since 2000 -- including the 2002 Hayman Fire southwest of Denver, the 2010 Fourmile Canyon Fire west of Boulder and the 2012 High Park Fire west of Fort Collins -- with historic fire effects in the region.

"It's true that the Colorado Front Range has experienced a number of large fires recently," said Schoennagel. "While more area has burned recently compared to prior decades -- with more homes coming into the line of fire -- the severity of recent fires is not unprecedented when we look at fire records going back before the 1900s."

In addition, tree-ring evidence from the new study shows there were several years on the Front Range since the 1650s when there were very large, severe fires. The authors looked at more than 1,200 fire-scarred tree samples and nearly 8,000 samples of tree ages at 232 forest sample sites from Teller County to Larimer County.

The study is one of the largest of its kind ever undertaken in the western United States. The team was especially interested in fire records before about 1920, when effective fire suppression in the West began in earnest.

"In relatively dry ponderosa pine forests of the West, a common assumption is that fires were relatively frequent and of low severity, and not lethal to most large trees, prior to fuel build-up in the 20th century," said Veblen. "But our study results showed that about 70 percent of the forest study area experienced a combination of moderate and high-severity fires in which large percentages of the mature trees were killed."

Along the Front Range, especially at higher elevations, homeowners and fire managers should expect a number of high-severity fires unrelated to any kind of fire suppression and fuel build-up, said Schoennagel. "This matters because high-severity fires are dangerous to people, kill more trees and are trickier and more expensive to suppress."

"Severe fires are not new to most forests in this region," said Sherriff. "What is new is the expanded wildland-urban interface hazard to people and property and the high cost of suppressing fires for society."

In addition, a warming Colorado climate -- 2 degrees Fahrenheit since 1977 -- has become a wild card regarding future Front Range fires, according to the team. While fires are dependent on ignition sources and can be dramatically influenced by high winds, the team expects to see a substantial increase in Front Range fire activity in the low and mid-elevations in the coming years as temperatures continue to warm, a result of rising greenhouses gases in Earth's atmosphere.

Source: University of Colorado at Boulder

Mountain pine beetles get bad rap for wildfires, study says

Following wildfires in 2011, a UW-Madison research team studied lodgepole pine trees in the Northern Rocky Mountains to examine whether earlier outbreaks of mountain pine beetles changed the ecological impact of the wildfires. Credit: Turner Lab

Mountain pine beetles get a bad rap, and understandably so. The grain-of-rice-sized insects are responsible for killing pine trees over tens of millions of acres in the Western U.S. and Canada over the last decade.

But contrary to popular belief, these pests may not be to blame for more severe wildfires like those that have recently swept through the region. Instead, weather and topography play a greater role in the ecological severity of fires than these bark-boring beetles.

New research led by the University of Wisconsin-Madison and the Washington State Department of Natural Resources provides some of the first rigorous field data to test whether fires that burn in areas impacted by mountain pine beetles are more ecologically severe than in those not attacked by the native bug.

In a study published this week in the Proceedings of the National Academy of Sciences, UW-Madison zoology professor Monica Turner and her graduate student, Brian Harvey, show pine beetle outbreaks contributed little to the severity of six wildfires that affected more than 75,000 acres in the Northern Rocky Mountains in 2011. They also show that the beetle outbreaks, which occurred from 2000 through 2010, have not directly impacted post-fire recovery of the forests. The study does not, however, address fire behavior, such as how quickly fires spread or how dangerous they are to fight.

While the findings may exonerate the insect scapegoats, they should also help ecosystem managers better respond to changes in the face of climate-driven disturbances, like drought and warmer temperatures.

Large, severe fires are typical in the lodgepole pine forests found throughout the region, even without mountain pine beetle outbreaks. However, as the climate has warmed, outbreaks and big fires have both become more common. The phenomenon of more beetles has meant more dead trees, and some have grown concerned about how beetle attacks and wildfires may interact.

"The conventional wisdom is that a forest of dead trees is a tinder box just waiting to burn up," says Turner, who has long studied the forest landscape of the Mountain West. "There were very little data out there but a lot of concern."

Forests attacked by bark beetles -- which burrow into the bark of lodgepole pines to mate and incubate their larvae -- can seem nothing more than ample kindling for a raging blaze, with their dead wood and dry, reddish-brown needles.

The burrows the beetles carve under the bark of pines, called galleries, choke off water and nutrient circulation in the trees. The trees die and, for the first couple of years, they hold on to their dry, lifeless needles. Scientists call this the "red stage," and some believe these trees could fuel more severe fires.

By year three, most beetle-attacked trees have entered the "gray stage," dropping their once green pine foliage, becoming needleless wood carcasses.

Earlier studies from Turner's group suggested that beetle outbreaks would not lead to more severe fires. But without actual fires, the interaction could not be tested.

However, in 2011, wildfires throughout eastern Idaho and western Montana -- in forests that had experienced varying mountain pine beetle outbreak impacts -- provided opportunity for the research team to begin to answer the question: Do the two disturbances, beetle attacks and wildfire, together change the ecological response of the forest to fire?

Fortunately for the team, among the burned areas studied were pine stands that had not been attacked by beetles. These areas served as controls. Others suffered a range of mortality from the beetles; in some stands, beetles killed nearly 90 percent of the trees prior to wildfire. The fires that raged also ran the spectrum of severity, allowing the researchers to compare a number of variables.

Some study plots comprised mostly live trees, while others contained mostly red-stage or gray-stage trees -- allowing the researchers to assess whether plots with red-stage trees (with dry needles) experienced greater levels of fire severity than plots with mostly gray-stage trees (no needles), as they and others had expected.

The study team examined ecosystem indicators of fire severity, such as how many trees were killed by fire and how much char covered the forests.

Engaging in what Harvey calls "post-fire detective work," in 2012, the scientific team evaluated fire severity in each study plot and stripped sections of bark from over 10,000 trees to determine what killed them, beetles or fire. Beetle galleries can remain visible under the bark even after fire.

As they sifted through the blackened trees and forest floor, the team became covered with ash and soot.

"We looked like coal miners when we were done," says Harvey.

They found that the severity of the outbreak and whether trees were in the red or gray stage had almost no effect on fire severity under moderate burning conditions.

Only under more extreme fire-burning conditions -- when it was hot, dry and windy -- did areas with more beetle-killed trees show signs of more ecologically severe fires, such as more deeply burned trunks and crowns (the part of the tree that includes its limbs and needles). The presence of more gray-stage trees actually had a stronger impact on fire severity than the amount of red-stage trees, to the surprise of the scientists.

Overall, however, Turner says the effects of beetle outbreaks on fire severity took a back seat to stronger drivers -- primarily weather and topography. Fire severity increased under more extreme weather, regardless of pre-fire outbreaks, and forest stands higher in the landscape burned more severely than those at lower elevation as fires moved uphill, building momentum.

"No one says beetle-killed forests won't burn," says Turner. "The data set looks at whether they burn with different severity compared to unattacked forests burning under similar conditions."

The team was also interested in whether beetle outbreaks slowed the recovery of the forests after fires. Lodgepole pines are adapted to fire, containing two types of seed-carrying cones: those that release seeds as soon as they mature and those that require fire to open, blanketing the forest floor with potential new life following a blaze.

By counting the number of post-fire tree seedlings in their plots, the researchers found very little beetle-related impact. Tree seedlings were most numerous where more of the fire-killed trees bore the fire-adapted, or serotinous, cones. Beetle-killed trees likely contributed to post-fire seedling establishment, too, as their seeds remain viable in cones if they are not consumed in fire. Only high-reaching char from tall flames reduced the number of seed-spreading cones.

The scientists emphasize the results may differ in other forest types or with different lengths of time between beetle outbreaks and fire.

"These are both natural disturbances, fire and beetle outbreaks," says Turner. "It's not surprising the ecosystem has these mechanisms to be resilient. What we as people see as catastrophes are not always catastrophes to the ecosystem."

Source: University of Wisconsin-Madison

Climate change not responsible for altering forest tree composition, experts say

Eastern US forest canopy. Credit: Mary Ann Fajvan, West Virginia University, Bugwood.org

Change in disturbance regimes -- rather than a change in climate -- is largely responsible for altering the composition of Eastern forests, according to a researcher in Penn State's College of Agricultural Sciences.

Forests in the Eastern United States remain in a state of "disequilibrium" stemming from the clear-cutting and large-scale burning that occurred in the late 1800s and early 1900s, contends Marc Abrams, professor of forest ecology and physiology.

Moreover, Abrams noted, since about 1930 -- during the Smokey Bear era -- aggressive forest-fire suppression has had a far greater influence on shifts in dominant tree species than minor differences in temperature.

"Looking at the historical development of Eastern forests, the results of the change in types of disturbances -- both natural and man-caused -- are much more significant than any change in climate," said Abrams, who is the Steimer Professor of Agriculture in the Department of Ecosystem Science and Management.

"Over the last 50 years, most environmental science has focused on the impact of climate change. In some systems, however, climate change impacts have not been as profound as in others. This includes the forest composition of the eastern U.S."

To determine how forest tree species have responded to changes in disturbance regimes, temperature and precipitation over long periods of time, Abrams collaborated with Gregory Nowacki, a scientist with the U.S. Department of Agriculture Forest Service office in Milwaukee, on a study of the tolerance and sensitivity of trees to various factors.

"Many ecological phenomena combine to direct vegetation trends over time, with climate and disturbance playing prominent roles," said Nowacki, who received his Ph.D under Abrams. "To help decipher their relative importance during Euro-American times, we employed a unique approach whereby tree species/genera were partitioned into temperature, shade tolerance and pyrogenicity classes and applied to comparative tree-census data."

The researchers compared presettlement -- original land survey data -- and current vegetation conditions in the eastern United States. Early tree surveys chronicle the westward progression of European land acquisition, with some dating back to the 1600s along the East Coast.

In the research, published online in Global Change Biology, researchers analyzed 190 datasets to determine the relative impacts of climate versus altered disturbance regimes for various biomes across the eastern United States. Because the Euro-American period from 1500 to today spans two major climatic periods -- from the Little Ice Age to the current Anthropocene -- the researchers expected vegetation changes consistent with warming.

"In most cases, however, European disturbance overrode regional climate change," Abrams said. "To the north, intensive and expansive early European disturbance resulted in the ubiquitous loss of conifers and large increases of Acer (maple), Populus (poplar) and Quercus (oak) in northern hardwoods, whereas to the south, these disturbances perpetuated the dominance of oak in central hardwoods."

Maple increases and associated mesophication -- the forest growing increasingly dense, cool, shady and moist in the absence of regular fire -- in oak-pine systems were delayed until mid-20th century fire suppression. This led to significant warm-to-cool shifts in temperature in which cool-adapted sugar maple increased and caused temperature-neutral changes in which warm-adapted red maple increased.

"In both cases, these shifts were attributed to fire suppression rather than climate change," Abrams said. "Because mesophication is ongoing, eastern U.S. forests formed during the catastrophic disturbance era followed by fire suppression will remain in climate disequilibrium into the foreseeable future."

Overall, he concluded, the results of the study suggest that altered disturbance regimes rather than climate had the greatest influence on vegetation composition and dynamics in the eastern United States over multiple centuries.

"Land-use change often trumped or negated the impacts of warming climate, and this needs greater recognition in climate change discussions, scenarios and model interpretations," he said.

Source: Penn State

This image shows a panda eating in China's Wolong Nature Reserve. Pandas habitat choices center around the ready availability of bamboo -- lots of bamboo. Credit: Sue Nichols, Michigan State University

Walter Dodds, university distinguished professor of biology (pictured), and Allison Veach, doctoral student in biology, are researching grassland streams and the expansion of nearby woody vegetation. They have studied 25 years of data on the Konza Prairie Biological Station and found that increasing fire frequency reduces the rate of woody vegetation expansion. Credit: Image courtesy of Kansas State University

Two Kansas State University biologists are studying streams to prevent tallgrass prairies from turning into shrublands and forests.

By looking at 25 years of data on the Konza Prairie Biological Station, Allison Veach, doctoral student in biology, Muncie, Indiana, and Walter Dodds, university distinguished professor of biology, are researching grassland streams and the expansion of nearby woody vegetation, such as trees and shrubs. They have found that burn intervals may predict the rate of woody vegetation expansion along streams.

Their latest research appears in the peer-reviewed journal PLOS ONE in an article "Fire and Grazing Influences on Rates of Riparian Woody Plant Expansion along Grassland Streams."

Grasslands in North America and across the globe are rapidly disappearing, Veach said, and woody plants are expanding and converting grasslands into forest ecosystems. This change in environment can affect stream hydrology and biogeochemistry, said Dodds, who has studied streams and watersheds on the Konza prairie for more than 20 years.

"This is an important issue regionally, because as trees expand into these grassland areas, people who are using grassland for cattle production have less grass for animals, too," Dodds said.

In their latest research, the biologists studied 25 years of aerial photography on Konza and observed the expansion of trees and shrubs in riparian areas, which include areas within 30 meters of streambeds. The researchers focused on three factors that affect grassland streams: burn intervals; grazers, such as bison; and the historical presence of woody vegetation.

Their analysis revealed an important finding: Burn intervals predicted the rate of woody vegetation expansion. Burning every one to two years slowed the growth of trees and shrubs, Veach said.

"Although we can reduce woody expansion by burning more frequently, we can't prevent it from occurring over time," Veach said. "Woody plant encroachment may not be prevented by fire alone."

The research shows the importance of burning to maintain the tallgrass prairie, Dodds said. While burning can help to slow the expansion of trees and shrubs, additional actions are need to maintain quickly disappearing grassland ecosystems.

"It's clear from this research that if you don't burn at all, these grassland streams basically are going to switch to forests and will not be grassland streams anymore," Dodds said.

Dodds and Veach also found that bison do not significantly affect woody vegetation expansion along streams. Previous Konza research has shown that bison do not spend significant time near stream areas, so they may not influence the growth of nearby trees and shrubs, Veach said.

Woody vegetation also may be expanding in grasslands because of more carbon dioxide in the atmosphere, Dodds said. Grasses and trees compete for carbon dioxide, and grasses are much better at conserving water and efficiently using carbon dioxide. As atmospheric carbon dioxide levels increase, it becomes easier for trees to gather carbon dioxide and gives them a growing advantage over grasses.

"The tallgrass prairie is almost nonexistent on the globe," Veach said. "In order for us to preserve tallgrass prairie, we need to look at woody encroachment because it has been an issue. Things like no fire or differences in climate change may allow woody plant species to competitively take over grasslands."

The biologists plan to continue studying water quality and quantity issues at Konza. Konza is an 8,600-acre tallgrass prairie ecological research site jointly owned by the university and The Nature Conservancy.

Source:  Kansas State University

Tinkering with the Tao of pandas

This image shows a panda eating in China's Wolong Nature Reserve. Pandas habitat choices center around the ready availability of bamboo -- lots of bamboo.
 Credit: Sue Nichols, Michigan State University

Good news on the panda front: Turns out they're not quite as delicate -- and picky -- as thought.

Up until now, information gleaned from 30 years worth of scientific literature suggested that pandas were inflexible about habitat. Those conclusions morphed into conventional wisdom and thus have guided policy in China. But a Michigan State University (MSU) research associate has led a deep dive into aggregate data and emerged with evidence that the endangered animal is more resilient and flexible than previously believed.

Vanessa Hull is a postdoctoral research associate at MSU's Center for Systems Integration and Sustainability (CSIS). She has spent three years stalking giant pandas in China's Wolong Nature Reserve. Given the pandas' elusive nature, Hull had a lot of down time.

So she bided her time plowing through literature on panda habitat selection, discovering inconsistencies and lack of consensus on matters crucial as scientists and policymakers struggle to protect the estimated 1,600 remaining wild giant pandas in the 21,300 square kilometers to which the animals have been relegated.

"Panda habitat selection is a complex process that we are still trying to unravel," said Jianguo "Jack" Liu, Rachel Carson Chair in Sustainability and CSIS director. "Pandas are a part of coupled human and natural systems where humans have changed so much in their habitat."

It has been thought pandas demanded a forest with fairly gentle slope (easier to mosey around in while seeking bamboo) at a certain elevation in original, old forest, an abundance of bamboo, and plenty of distance from people. These recommendations, Hull said, come from often-scant research because pandas are difficult animals to study.

"Pandas are difficult to observe and follow in the wild, we're always 10 steps behind them," Hulls said. "We don't know why they're there -- or where they were before and after. There's a lot of guesswork."

Vanessa and her colleagues drew up analysis of all the research projects and sought to separate studies that focus on where pandas live from studies that examine what kind of choices pandas make when multiple types of habitat are available. They discovered that pandas may not be as picky as thought.

The research shows, for instance, that pandas are willing to live in secondary forests -- forests that have been logged and have regrown. They also don't seem as selective about slope, and are willing to climb depending on which of the many varieties of bamboo is growing, or what type of forest it was in. Same for elevation, and the amount of sunshine that hits a piece of panda home.

That's good news. Indications that forests once cut clean by timber harvesting can return to acceptable panda habitat validate current bans on forest harvesting.

They also found that there is a complex relationship between trees and bamboo. Pandas choose different forest types as places to spend their time, as long as bamboo is available.

Hull said consensus would be helpful for future panda habitat research, since the future guarantees change.

"It's exciting to see the flexibility pandas have, or at least see that pandas are choosing areas I didn't think could support them," Hull said. "It gives you hope. They've survived throughout many challenges over so many millions of years, it would be sad to think humans came along and threw it all away. This also suggests we should stay on board and try to make things better for them."

Source: Michigan State University