Research > Research Highlights
RNR Research Highlights
Breeding the perfect Oyster?
Dr. John Supan - AgCenter, RNR, and Sea Grant scientist, was recently featured on WWL-TV New Orleans discussing his triploid oyster program.
Professor Supan began researching this concept of cross breeding oysters back in 1993. After roughly nine years of work and experimentation, he and his team had a break through. In the spring of 2002, they successfully produced what they call a "triploid" oyster. “We have not inserted strange genes into these oysters. The chromosomes in these oysters were in the oysters already. It's just part of a breeding process,” Supan said. "
"They retain their winter fat acquired during the winter time, they don't burn it off during the summer to spawn, which causes their meat yield to drop and become watery. The triploids stay fat all summer long" said Supan.
See the video, and read the rest of the fascinating details HERE.
LIFT2 Grants Awarded to Three RNR Faculty
LSU has awarded 15 grants totaling $500,000 to faculty members through its new LIFT2 (Leveraging Innovation for Technology Transfer) grant program, which provides funding to validate the market potential of the faculty members' inventions. Grants are for up to $50,000. LSU President F. King Alexander says in a prepared statement that "this program will help to see many of these projects advance from basic research to market." Results of the research from the first grants are expected within a year. The grant awardees were selected from among 47 applications.
Congratulations are in order for three of our Faculty members receiving these prestigious awards:
Professors Todd Shupe and Richard Vlosky in the School of Renewable Natural Resources, along with Dr. Jim Richardson in the E. J. Ourso College of Business Administration on the LSU A&M campus received one of these these for their project titled: “Reclaiming Chromated Copper Arsenate (CCA) from Decommissioned Preservative-treated wood: Technology, Economics, and Markets”
Assistant Professor Julie Anderson Lively in the School of Renewable Natural Resources, also received one of these awards. The title of her project is “Packaging and storage of a new blue crab bait”
Dr. Todd Shupe (PI) is Professor and Director of the Wood Durability Laboratory, Louisiana Forest Products Development Center, School of Renewable Natural Resources at the Louisiana State University Agricultural Center in Baton Rouge, La. The laboratory is world recognized as a leading research and testing laboratory and is ISO/IEC Standard 17025:2005 accredited. Dr. Richard Vlosky (co-PI) is Director of the Louisiana Forest Products Development Center and Crosby Land and Resources Endowed Professor in Forest Sector Business Development at the Louisiana State University Agricultural Center in Baton Rouge. Dr. James Richardson (co-PI) is John Rhea Alumni Professor of Economics and Director of the Public Administration Institute in the E. J. Ourso College of Business Administration at Louisiana State University in Baton Rouge, Louisiana. Dr. Richardson has also served as Chairman of the Department of Economics, Acting Dean of the College of Business Administration, and Associate Vice Chancellor for Academic Affairs at Louisiana State University.
The wood-preservation industry is a $4.5 billion industry in the U.S.. For all species, a total of 8.2 billion board feet of lumber and 59.4 million cubic feet of logs are estimated to have been treated with waterborne preservatives in 2007. In Louisiana, the forest product industry ranks as one of the top manufacturing industries, employing almost 30,000 workers, second to petro-chemicals, with an annual payroll of over one billion dollars and contributes over $4.9 billion annually to the state’s economy. Southern pine is the dominant species for treated wood and nearly half of all southern pine lumber is preservative treated. It is important for Louisiana non-industrial forest landowners that Louisiana maintains a viable wood preservation industry so the landowners can obtain maximum value for their timber.
The main goal of this multi-institutional research is to determine the suitability of spent CCA-treated wood as a source for (1) recycled, “green” CCA and (2) raw bio-polyols, obtained via continuous microwave liquefaction, in the fabrication of “green” spray-foam insulation. Specific objectives are to (1) determine the technical efficacy, (2) economic feasibility and (3) market structures of an innovative patented processes at the pilot-scale level. This is unique research that is aimed at the development of a closed-loop spent CCA-treated wood pole recycling process with no discharge of solid waste into the waste stream. The technology has been covered in two US patents awarded to Dr. Shupe.
Crab bait is big business: According to Dr. Lively, over 40 million pounds of blue crab are harvested annually in Louisiana, and the most common bait is East Coast caught Atlantic menhaden shipped frozen to the Gulf of Mexico. This is costly and becoming prohibitive as the fish is overfished. Dr. Lively's lab has developed a new bait using waste from the seafood industry in Louisiana, which is under a provisional patent. The goal of her project is to take the feasibility test results from academia and produce a product available for use in the commercial industry. The objectives of this project will be to 1) improve storage techniques for optimal mass production, and 2) evaluate the bait in the black drum fishery. This new bait would be applicable for bait markets across the Gulf of Mexico and the East Coast.
The New GPS: Gobbler Positioning System
An article from the May 2, 2014 issue of Field and Stream features our current wildlife ecologist, Dr. Bret Collier, and our former wildlife ecologist, Dr. Mike Chamberlain. The use of GPS technology to study the habits and movements of turkeys is highlighted. Interesting stuff. The article can be viewed online, here.
LSU AgCenter, Nicholls State Collaborate on Gar Fish
BATON ROUGE, La. – Researchers from the LSU AgCenter and students from Nicholls State University recently collected alligator gar at the LSU AgCenter Aquaculture Research Station in Baton Rouge in an effort to improve the fish populations in areas where they are no longer found.
Christopher Green, the lead researcher on the project at the station, is working with biology students at Nicholls to address the spawning behavior of the fish. And for the past four years, Green has been looking at ways to keep the alligator gar a viable species in southern Louisiana and other parts of the Mississippi River.
Research Highlight: Blue Crab Bait Could Improve Crab, Shrimp Industries
BATON ROUGE, La. – A new gelatin-like bait using shrimp waste could improve the way blue crabs are caught along the coast of Louisiana and add value to the state’s shrimp processing industry.
Julie Anderson, a crustacean specialist with the LSU AgCenter and RNR Faculty memeber, is working on a crab bait that could replace Atlantic menhaden, the current bait used.
The menhaden, also known as pogy, is shipped from the East Coast, Anderson said, but stocks are declining. The Atlantic State Marine Fisheries Commission put a limit on how much menhaden can be caught. Anderson said this is driving up the price of Atlantic menhaden.
Menhaden also is caught in the Gulf of Mexico, but it is rarely used for bait.
“Gulf-caught menhaden is valuable as its own separate fishery,” she said. “There are some fishermen that used to sell it as bait, but it is more valuable to use as Omega-3 oils – fish oils – that it is just not worthwhile to sell as bait.”
Anderson worked on a project manufacturing baits at the University of Delaware. She was trying to find a replacement for horseshoe crabs used as bait in eel and whelk fishing.
She is applying the same techniques to develop a blue crab bait that can replace menhaden.
Anderson tried mixing commercial-grade gelatin with byproducts from oysters, shrimp and crabs – all things blue crabs eat. Tests showed that the crabs were most attracted to the baits with shrimp in them.
Anderson said about a third of a shrimp – such as the shell and the head – is waste, and shrimp processors typically have to pay to have the waste hauled away. Finding a use for the waste can cut down on costs while bringing in money.
“If we can create even just a very small value to this waste product, then some of those processors could make a little more money,” she said.
The researcher is testing different amounts of shrimp and gelatin to make a bait that would first attract the crabs and also hold up in the water as well as be easy to store and handle.
“Preliminary fields work had very similar catches between normal menhaden and our bait,” Anderson said.
She tested the baits in waters with varying salinity levels and found that in waters with high salinity, smaller predators, such as minnows and small crabs, will feed on the bait and break it down faster. This was not a problem in fresher water.
Anderson says it appears the manufactured bait may last longer in the water than menhaden. With longer-lasting bait, fishers wouldn’t have to go out as often to check their traps, which would cut down on fuel costs.
Baits manufactured in Louisiana also decrease shipping costs. While menhaden bait is kept frozen, this manufactured bait may not need to be frozen. Anderson said it would likely be less costly than using menhaden.
“Even if it is just a few cents cheaper per bait, it would definitely add up over the year,” she said.
Anderson has a graduate student working on the project during the next two years, and she hopes to have a product ready for the market at the end of that period.
Artificial reefs could stem coastal land loss
BATON ROUGE, La. – Louisiana’s issues with coastal land loss are well-documented. Scientists estimate that since 1930 as much as 25 square miles of land per year have been lost in the Mississippi River delta area. Much of these losses can be traced to land subsidence – land simply sinking and being covered by water – and erosion from wave energy.
Megan Lapeyre, an estuarine ecologist with the LSU AgCenter’s School of Renewable Natural Resources and the U.S. Geological Survey, is studying engineered reefs and examining how these reefs perform in stabilizing land primarily in areas of high wave energy.
“We are studying these reefs in three different areas. One in the Vermilion Bay area, one in Grand Isle and another in the Biloxi marsh area,” she said.
Lapeyre said one goal of the studies is to answer just how effective reefs are for shoreline stabilization. “Ideally, they would assist in creating marsh,” she said. “At this point, it is too early to tell.”
Both public and private entities have provided financial support, with funding coming from the Louisiana Department of Wildlife and Fisheries and The Nature Conservancy.
Lapeyre said the engineered reefs may not only provide shoreline stabilization but also create habitat for marine organisms. “The reefs are designed to encourage oyster recruitment and offer a place for fish to spawn or be a refuge from predators,” she said.
Two designs are being used for the construction of the reefs.
One is a concrete-rebar model that is triangular-shaped and is placed in an interlocking fashion. The rebar is designed to degrade in approximately 15 years, leaving behind a reef consisting of recruited organisms.
The second reef is a concrete mixture shaped in a circular form resembling a tire. Researchers hope it, too, will become covered with living organisms.
Lapeyre reported that preliminary data had shown the reefs have provided habitat for a number of fish and crustaceans, including blue crab, bay anchovies and gulf menhaden (pogy). Researchers used a variety of nets to sample the organisms that were using the reefs.
Another facet of the research is examining the role of the reefs in filtering water. The successful recruitment of a viable oyster population is essential for water filtration to occur, Lapeyre said.
“The filtration abilities of the oysters would be a primary contributor to enhancing water quality and clarity, but the reefs’ ability to absorb wave energy would also be a factor,” she said.
Lapeyre noted that not all sites experiencing coastal land loss are suitable for the reefs. She said land that is subsiding would not be an ideal location. Areas that experience high boat traffic and are exposed to wave energy created by localized storms would be better suited.
Another factor in site selection involves choosing locations that are conducive to oyster survival. In order for the reefs to be successful, oysters will play a crucial role. Issues such as water salinity and the firmness of the water bottom should also be considered, Lapeyre said.
“Many of the questions can’t be answered within a short time. Additional monitoring time will be needed to determine whether this is a viable solution to shoreline stabilization,” she said.
The origianl article, by Craig Gautreaux can be see on the LSU Agcenter.com website
Cooperative Research Unit Corner - Research on Louisiana's Bald Eagles
Wildlife Management Institute’s Outdoor News Bulletin is hilighting Dr. Alan Afton’s Bald Eagle research in it's "Cooperative Research Unit Corner". Research being conducted by the Louisiana Department of Wildlife and Fisheries in collaboration with the USGS Louisiana Cooperative Fish and Wildlife Research Unit, US Fish and Wildlife Service, and Louisiana State University is examining the change in the eagle population over time and looking at what habitat types the birds are currently using for nesting. The Bulletin and all the details are available on the Wildlife Mangaemnt Institute's website. Read about nteresting research to help preserve our National Symbol.
Workshop Focuses on Wood-Based Bioenergy
HAMMOND, La. – The U.S. forestry industry has migrated from the Pacific Northwest to the South over the past two decades, providing additional opportunities for Southern forest landowners, an LSU AgCenter business development expert told an audience at a workshop on forest-based bioenergy.
Emerging biomass-to-energy markets have been driven by increasing interest in renewable energy sources, said Rich Vlosky, director of the Louisiana Forest Products Development Center in the LSU AgCenter.
“Government mandates and economic trends determine what new markets will look like,” Vlosky said. “Alternative uses of wood products require a shift in thinking.”
Short-rotation woody crops and “energy thinnings” can provide good sources of energy, but markets are needed to give growers incentive to invest in producing trees for biofuels, he said.
Worldwide, 17 percent of energy comes from renewable sources, and U.S. renewable energy has been inching up for decades to about 8 percent, half of which comes from wood, Vlosky said. Globally, 4.6 million tons of wood pellets are used to produce energy, mostly in Europe. Of that, 36 percent comes from the United States, with Sweden responsible for 20 percent of worldwide use.
“The wood sector for alternatives is going to grow – but slowly,” Vlosky said. “Forest landowners are in the best position possible. It’s a no-lose proposition unless the crop is mismanaged. Cheap natural gas, however, has been a game changer.”
The workshop was one in a series that mark the culmination of two three-year studies funded by federal grants. The projects focused on developing marketing strategies for expanding bioenergy opportunities for the forest sector, Vlosky said.
The AgCenter joined with the Louisiana Business and Technology Center at LSU to deliver workshops across the state. In addition to Vlosky’s presentation on wood-based bioenergy markets and potential opportunities for Louisiana, Matthew Wiggins with the LBTC showed attendees how to develop a viable business plan using wood for energy, Vlosky said.
“We’re using the LBTC mobile classroom for these pilot workshops,” he said.
Stouffer Lab Brings Good News From the Rainforest
Some good news out of the Amazon rainforest: given enough time, deforested land can rebound enough to host bird species that had previously deserted the area, according to a recent study in The Auk.
Between 1992 and 2011, a team led by Philip Stouffer of Louisiana State University tracked the movements of birds through fragmented rainforest in the Brazilian Amazon. Using soft nylon stretches called mist nets, they snagged nearly 4,000 birds at the margins between old growth forests and tracts of between old growth rainforest and forest recovering after being abandoned by cattle ranchers.
As the so-called secondary forest regenerated, birds crossed the borders more frequently, the team found. These areas of regrowth become more habitable to birds with time, although the results suggest that it can take at least a decade or two for species to return.
Nature faces disasters, disruptions
BATON ROUGE, La. – Man-made modifications in the Mississippi River Valley – levees, cut-offs and dams – have all caused changes in the ecology of the Atchafalaya Basin and similar areas, Wes Cochran, a graduate student in the School of Renewable Natural Resources, told a conference audience recently.
Those and effects of natural and man-made disasters and disruptions were featured as scientists presented results of some of their research in the fourth Louisiana Natural Resources Symposium on Aug. 1-2 on the LSU campus in Baton Rouge.
The fourth in a series of biannual conferences was presented by the LSU AgCenter School of Renewable Natural Resources.
“The conference is focused on the effects of human and natural changes on forested and wetland ecosystems and wildlife,” said Todd Shupe, of the AgCenter’s Louisiana Forest Products Development Center and one of the organizers of the event.
The move from riverine flooding to rain-dominated flooding has disrupted the basic ecology of the remaining fragments of bottomland hardwood ecosystems, Cochran said.
The changes constrict and isolate floodplain habitat, causing less flooding “with longer, deeper floods in some areas and cessation of floods in others,” Cochran said. The results include a region-wide shift in vegetation composition with more shade-tolerant and flood tolerant species.
Urban neighborhoods moving into rural areas are another demonstration of human-induced disturbances that affect ecosystems through the Gulf Coast states, said Francisco Escobedo, of the University of Florida at Gainesville.
“What happens is forest systems – working forests – become urban and lose their ‘ecosystem services’ that include carbon storage, timber availability and water quality and quantity,” Escobedo said.
Similar to other disturbances, urbanization can alter ecosystem structure and function, he said.
Another example of “man-made” problems is the growth of feral hog populations, said Kim Marie Tolson, of the University of Louisiana-Monroe.
“Hogs are a human-induced disaster on our landscape,” Tolson said. “They have the highest reproductive potential of any large mammal in North America.”
The feral hog is the No. 2 game animal harvested in the United States – second only to white-tail deer – and can tolerate a wide range of habitat types and climates, she said.
Tolson’s research focuses on feral hog reproduction in Louisiana. “Their proclivity to reproduce combined with their omnivorous diet has led to many problems for the forest and agriculture industries.”
Nonhuman-caused disasters include floods and hurricanes. And hurricanes can have a substantial influence on freshwater fisheries, said LSU AgCenter researcher Michael Kaller.
“Hurricanes are somehow changing the biogeographic habitats of these systems,” Kaller said. Louisiana freshwater fisheries had fewer fish following hurricanes Katrina and Rita because of changes in water quality.
In addition, the opening of the Morganza Floodway in 2011 had a profound effect on fish. “After the Morganza flooding, the slate was wiped clean,” Kaller said. “This is a different Atchafalaya Basin.”
Fish were negatively affected, primarily through a loss of diversity, including recreationally and economically important species, he said. Changes to habitat may be a far greater source of long-term mortality and may impede recovery.
“Although hurricanes are natural phenomena in coastal landscapes, their intensity and frequency can exceed the ability of freshwater resources to respond,” Kaller said.
Along with creating problems with fisheries, hurricanes also can disrupt many different forms of wildlife.
Scott Durham, of the Louisiana Department of Wildlife and Fisheries, described how Hurricane Isaac affected deer populations in 2012.
“White-tail deer were especially affected in unprotected regions of St. Bernard and Plaquemines parishes,” he said. “Additional significant flooding occurred in the marshes and swamps adjacent to lakes Pontchartrain and Maurepas, where wind-driven water depths were estimated at over 5 feet above normal in some areas.”
About 90 percent of the season’s fawns were lost along with moderate adult mortality, Durham said.
After the flood, however, came a new period of “green-up” – like spring, Durham said. This provided the surviving deer “a high period of nutritional availability.”
“Most coastal regions are adapted to floods, and habitats recover,” he said. “However, subsidence and other contributing factors in coastal decline appear to make these regions and associated wildlife more and more vulnerable.”
Alligator Diet is the Focus of Aquaculture Research Station Project
1/28/2013, The Advocate -- Millie Williams, Senior Research Associate with the LSU AgCenter's Aquaculture Research Station, is working on a study that could do for Louisiana’s $60 million alligator farming industry what science has already done for the cattle, pork and poultry industries.
Robert Reigh, director of the research station, says LSU is set to open its new Alligator Research Station just outside Baton Rouge city limits in early March.
Since the early 1990s, alligator farmers have been asking for help in identifying the right food mixture and the right conditions in which they can grow their alligators quickly to marketable size and sell them, Reigh said.
About five years ago, the farmers pooled their money — about $160,000 — to pay for the Alligator Research Station.
Once the building is completed, researchers will have adequate space to take in young alligator hatchlings and nurture them until they reach marketable size of about 4 or 5 feet.
LSU AgCenter Researchers Testing Oil Cleanup Chemical Toxicity
BATON ROUGE, La. – 12/18/12 - LSU AgCenter scientists are working with researchers at Columbia University and Iowa State University on an environmentally friendly substance that could be used to clean up oil spills.
Andy Nyman, an LSU AgCenter wetlands biologist, and Chris Green, an LSU AgCenter toxicologist, are testing the chemical’s toxicity on killifish, a baitfish known more commonly in Louisiana as cocahoe minnows. The $211,000 project is being funded for three years by the U.S. Environmental Protection Agency and the National Science Foundation.
The project came in reaction to the 2010 BP oil spill in the Gulf of Mexico and the recognized need for a more effective, yet environmentally friendly dispersant, Nyman said.
The work focuses on developing less-toxic materials, called surfactants, which are important ingredients in many household products and in oil spill dispersants. Chemicals are classified as surfactants if they have surface properties that allow them to help oil and water mix.
Iowa State researchers are making a new surfactant through a fermentation process using bacteria, soybean wastes and bagasse. Iowa State researchers are working to make the fermentation more efficient, Nyman said, while Columbia researchers are studying the effectiveness of the surfactant’s potential to disperse crude oil.
The oil spill dispersant used now is known by its proprietary name Corexit. It is toxic to marine life, Nyman said. But oil that has been dispersed with Corexit is even more toxic, and its toxicity is longer lasting, possibly as long as six months based on laboratory studies.
The research will not produce immediate results that can soon be used commercially, Nyman said. “This is very preliminary research. I think we’re a decade or two away from seeing something in the marketplace. But I hope I’m wrong.”
Green said he has been testing the toxicity of more common surfactants and household products, such as dishwashing detergent, on killifish to help non-scientists relate to toxicity data. But those results are not yet published.
Killifish is a good species for testing because it adapts to a wide range of salinity, and other scientists have used it for toxicity testing, Green said.
The material being produced by Iowa State researchers should be available by late December or early January, he said.
LSU AgCenter and Sea Grant coastal ecologist Brian LeBlanc said his role in the project is to inform the public in coastal areas about the project and potential benefits of developing safer dispersants.
A mobile lab is planned for 2013 to demonstrate the toxic effects of current surfactants, crude oil and common household detergents using fish and possibly invertebrate larvae, LeBlanc said.
“We’re not trying to say the use of dispersants was necessarily a bad thing, in some situations they may be needed,” LeBlanc explained. “We’re simply trying to develop less toxic more effective methods of dispersing oil.”# # #
Researcher Tracks Changes at University Lakes
16 Nov 2011 - Trying to keep the University Lakes in Baton Rouge clean and healthy is a goal of LSU AgCenter researcher Yi Jun Xu, associate professor in the School of Renewable Natural Resources.
For the past three years, Xu has used funds from the Louisiana Board of Regents Equipment Enhancement Fund to study the lake’s health.
“When the project began in 2008, the focus was on two areas – enhanced teaching in water resources and to provide sophisticated, state-of-the-art equipment for surface water research,” Xu said.
Xu and his graduate students receive measurements of the dissolved oxygen, pH and water temperature every 15 minutes from equipment in the lake. He said his data can be used by state agencies and others interested in water quality.
The Fall 2011 Louisiana Agriculture issue contains several articles by RNR faculty
The fall 2011 issue of Louisiana Agriculture focuses on our state’s water resources. These resources must be sustained and improved for the future well-being of Louisiana. The LSU AgCenter has made a major commitment to water quality. Our scientists are finding ways to prevent nutrient runoff, which is from a variety of sources, into our streams and waterways and to mitigate the damage from saltwater intrusion following hurricanes. Learn more by reading this issue, and please contact the individual authors if you have questions or need more information. Or you can contact the editor, Linda Benedict. The LSU AgCenter is dedicated to Louisiana’s economic development.
Selected content, contributed by RNR Faculty and students includes:
- LSU AgCenter is committed to water quality
Y. Jun Xu
- Keep Louisiana’s water resources plentiful and good
D. Allen Rutherford
- Nutrient Removal from Atchafalaya during 2011 flood
April Bryant-Mason and Y. Jun Xu
- Forestry Best Management Practices and stream water dissolved oxygen
Y. Jun Xu, Abram DaSilva and April Bryant-Mason
- Riverine Sediment and the Louisiana coast
Y. Jun Xu and Timothy Rosen
- Water Depth enhances quality, provides fish refugia in the Atchafalaya River Basin
Michael D. Kaller and William E. Kelso
- Wetland Restoration with agricultural techniques
- Water Resource Use in Louisiana Aquaculture
Robert P. Romaire, W. Ray McClain and C. Greg Lutz
Tropical Birds Return to Harvested Rainforest Areas in Brazil
22 June 2011 - During a 25-year period, many bird species in Brazilian rainforest fragments that were isolated by deforestation disappeared and then reappeared according to a research paper published June 22 in PLoS One, an online, peer-reviewed journal.
Although species loss following habitat conversion can be inferred, long-term observations are necessary to accurately identify the fate of bird populations, said Philip Stouffer, an ornithologist with the LSU AgCenter and lead author of the paper “Understory bird communities in Amazonian rainforest fragments: Species turnover through 25 years post-isolation in recovering landscapes.”
Stouffer’s research, funded for the past five years by a grant from the National Science Foundation and conducted in cooperation with Projeto Dinâmica de Fragmentos Florestais, Instituto Nacional de Pesquisas da Amazônia and the Smithsonian Tropical Research Institute in Manaus, Brazil, shows bird species began reappearing following a 10-year hiatus (click to enlarge images).
Stouffer and his colleagues – Erik Johnson, who was Stouffer’s graduate student and is now with the National Audubon Society, Richard O. Bierregaard at the University of North Carolina, Charlotte, and Thomas E. Lovejoy with the Heinz Center in Washington, D.C. – measured bird populations in 11 forest fragments ranging from about 2.5 acres to 250 acres in the Amazon rainforest near Manaus, Brazil.
Bierregaard and Lovejoy set up the project in the 1970s, and Bierregaard managed it until 1993. Stouffer joined the team in 1991.
When the project began, bird populations were measured using established mist-net protocols before the forests were cut. During the first year after cutting, the bird species disappeared in what the researchers call “localized extinction,” meaning a species has disappeared from a particular area.
The area is fragmented in “cookie cutter chunks” as a result of government policies that encouraged use of the land – mostly for cattle – but required landowners to leave a portion of the area uncleared.
Bird populations were measured before the deforestation process began and then again in 1985, 1992, 2000 and 2007. During the first 10 years, birds abandoned the fragments and became “extinct.” Then during the past 20 years, many species have come back, but others have gone extinct or remained extinct.
Agriculture has diminished, and although some of the fragments are deteriorating, the matrix between the fragments and nearby forests is recovering into forest, Stouffer said. “Early on, the small fragments lost most of their understory birds, and the area that was cut had no forest birds at all.”
Between the time the forest fragments were created and 2007 when the most recent measurements were taken, all fragments lost bird species, Stouffer said. Losses ranged from below 10 percent in the largest fragments to around 70 percent in the smallest fragments.
Analysis of individual time intervals revealed that the 2007 result was not because of gradual species loss beginning at isolation; both extinction and colonization occurred in every time interval. In the last two samples – taken in 2000 and 2007 – extinction and colonization were approximately balanced.
The extinction process started with bird species leaving or dying out. Now, they’re coming back. “A handful of species have ‘gone extinct,’ but many more species are in flux,” Stouffer said. “They come and go. Some of the areas have 20 to 25 years of forest regrowth.”
The project measured only understory, resident birds and not those that live in the forest canopy or may migrate. “We don’t know the actual demography of the birds,” Stouffer said. But the counts include estimates of uncounted birds.
“We’ve been looking at the rate of extinction and colonization,” Stouffer said. “Our samples are snapshots in time. And they show that forest fragments have potential to recover their biodiversity if they’re imbedded in a landscape that can recover. They’re not doomed.”
The research shows how birds exist within a human-modified environment and the effects of allowing a forest to regenerate, Stouffer said. “We can consider a balance of abandoned and returned forests because within a 20-year window, birds will begin to treat the fragments as continuous forest.”
Landscape dynamics must be considered as second-growth structure and overall forest cover contribute to processes in fragments, Stouffer said. Using a method that accounts for imperfect detection, they estimated extinction and colonization based on standardized mist-net surveys within discreet time intervals – one to two pre-isolation samples and four to five post-isolation samples.
“Of the 101 species netted before isolation, we detected 97 in at least one fragment in 2007,” Stouffer said. “Although a small subset of species is extremely vulnerable to fragmentation and predictably goes extinct in fragments, developing second growth in the matrix around fragments encourages recolonization in our landscapes.”
Species richness in these fragments now reflects local turnover, not long-term attrition of species. We expect that similar processes could be operating in other fragmented systems that show unexpectedly low extinction.
“By combining one of the first controlled fragmentation experiments in tropical forests with the opportunity for long-term observation, this study provides verification that local extinction is accompanied by continual recolonization, dependent on habitat size,” said Saran Twombly, program director in NSF’s Division of Environmental Biology, which funded the research. “The results bolster island biogeography theory in one of the most diverse regions on the planet.”
photos: Dr. Phillip Stouffer, LSU School of Renewable Natural Resources, LSU Agcenter, email: firstname.lastname@example.org
author: Rick Boren, LSU AgCenter, 22 June 2011, email: email@example.com