Recent Land Use Change in the Western Corn Belt Threatens Grasslands and Wetlands

The recent boom in the biofuel industry, in part due to incentives that promote the conversion of grassland to corn and soybean cropping, is reshaping the landscape of the US Corn Belt. Wright et al. (2013) sought to study the extent to which this land use conversion is occurring, and what its implications may mean for the environment.  The researchers used the National Agricultural Services (NASS) Cropland Data Layer (CDL) to examine the rate at which grasslands have been converted into corn/soy cultivation over five states of the Western Corn Belt: North and South Dakota, Nebraska, Minnesota, and Iowa.  The authors considered the agronomic and environmental attributes of lands on which grassland conversion was occurring, as well as the effects on nearby waterfowl nesting sites, and included these in the results as well.  The results of this study show that the rate at which land was being converted has not been seen in the US since the advent of the mechanization of US agriculture in the 1920s.  The implications of this rate are bleak as it threatens waterfowl populations, soil quality, and water resources.  The authors recommend we shift to biofuels produced from perennial feedstocks, as these fuels have desirable traits with respect to net energy and greenhouse gas balances and wildlife conservation. —Anthony Li

Wright, C. K., Wimberly, M. C., 2013. Recent land use change in the Western Corn Belt threatens grasslands and wetlands.  Proceedings of the National Academy of Sciences of the United States of America published ahead of print February 19, 2013

Eemian interglacial reconstructed from a Greenland folded ice core.

The Eemian interglacial period occurred between 130,000 and 115,000 years ago. Previous attempts to extract an ice core from this time period have been unsuccessful, but scientists in Greenland have recently been successful. The North Greenland Eemian Ice Drilling (NEEM) team, extracted an ice core from the Northern Greenland ice sheet and were able to analyze atmospheric changes during this time using air bubbles frozen in the ice. Using stable water isotopes, the data reveal that surface temperatures at NEEM peaked at 8 ± 4°C above the mean of the past millennium during the Eemian interglacial period, followed by gradual cooling (Dahl-Jenson et al. 2013). The scientists also found that between 128,000 and 122,000 years ago the thickness of the ice decreased by 400 ± 250 meters, reaching surface elevations of 130 ± 300 meters below present levels. Furthermore, melting and movement patterns of ice before the Eemian interglacial period indicate that significant melting and refreezing events occurred during these years.¾Olivia Jacobs

Neem Community Members, 2013. Eemian interglacial reconstructed from a Greenland

folded ice core. Nature 493, 489–494. 

Dune Infiltration Systems for Reducing Stormwater Discharge to Coastal Recreational Beaches

The present issues related to untreated stormwater are significant and must be taken seriously, not only for the sake of aquatic ecosystems where this polluted water is discharged, but also for the sake of human health. After a rainfall, the concentration of fecal bacteria entering coastal waters, as a result of unfiltered discharged runoff, often exceeds the state and federal bacteria limits that are considered safe for human contact; and unfortunately, everyday beach-goers are ignoring the eminent health threats that these waters pose. Direct human contact with the stormwater or the area that receives its discharge can lead to symptoms of gastrointestinal, respiratory, ear, eye, nose and skin infections; yet, contact with discharging stormwater still occurs, despite visible warnings.  Previous studies have shown success capturing bacteria from stormwater using sand filters, so Burchell and his colleagues (2012) arranged the idea of a Dune Infiltration System (DIS) to divert stormwater from existing pipes and into dunes, where the water can be filtered through sand and ground water before it is discharged to the coastal waters. They constructed three DISs in Kure Beach, North Carolina for demonstrational study, and found that the performance of these systems was more successful than expected and that they are a low-cost and low-tech solution for diminishing stormwater discharge and associated fecal bacteria to recreational beaches. –Genevieve Heger

            Burchell, M., Hunt, W., Price, W. D., 2012. Dune Infiltration Systems for Reducing Stormwater Discharge to Coastal Recreational Beaches. Bio&Ag Engineering, 400-412

The Relationship between Embolism Resistance and Droughts for Global Forest Ecosystems

Global climate change predictions indicate increasing temperatures and shifts in rainfall patterns, resulting in increased severity and frequency of drought. These droughts are likely to cause forest decline around the world, resulting in decreased net primary productivity and plant mortality, largely attributable to hydraulic failure. Through a process called embolism, drought stress causes gas to become entrapped in the vascular systems of plants. Embolism thus prevents water transport necessary for photosynthesis to occur in plants. If a plant is unable to conduct photosynthesis, it will eventually desiccate and die. The threshold limits for hydraulic failure across different species and environments is largely unknown. Choat et al. (2012) compared the vulnerability of a variety of woody species based on drought-induced embolism. The authors found that seventy percent of the 226 forest species studied operate within narrow hydraulic safety margins against damaging levels of drought stress. If these margins are exceeded, long term implications including decreased productivity and survival are affected. These safety margins are largely independent of mean annual precipitation, thus demonstrating that there is global convergence in the vulnerability of forests to drought, meaning that all forest biomes are equally susceptible to hydraulic failure, regardless of initial rainfall environments.

—Hilary Haskell

            Choat, B., Jansen S., Brodribb, T., Cochard, H., Delozn, S., Bhaskar, R., Bucci, S., Feild, T., Gleason, S., Hacke, U., Jacobsen, A., Lens, F., Maherali, H., Martinez-Vilalta, J., Mayr, S., Mencuccini, M., Mitchell, P., Nardini, A., Pitterman, J., Brandon Pratt, R., Perry, J., Westoboy, M., Wright, I.,

Models Predict Potential Consequences of Climate Change for Primary Production and Fish Production in Large Marine Ecosystemsev

Over the past three decades, the waters of the Northeast Atlantic have warmed faster than the global average resulting in exaggerated changes in the distribution and abundance of fish species in this area. Climate change is expected to change productivity of fisheries in the future but ecosystem specifics are not well understood. Many populations, especially poorer populations, rely on marine fish as a main source of protein, making these populations especially vulnerable to the decline in the productivity of fisheries. Because of the complex impacts of climate change on marine ecosystems, it is challenging to predict responses at all ecological levels and spatial scales.

Climate change influences fishery production through effects on primary production, food web interactions, and the life history and distribution of target species. Changes in primary production are strongly influenced by changes in the physical and chemical environment, while changes in the food web are also influenced by primary production. Blanchard et al. (2012) combine physical-biogeochemical and size-structured community models with temperature effects to project future effects of climate change on fish biomass and production in 11 large regional domains which include most productive areas of the shelf seas. Changes in fish production are shown to be most strongly influenced by phytoplankton production. Blanchard et al. predict potential declines in fisheries production to be 30–60%, most notably in the Indo-Pacific, and the production of pelagic predators to increase by 28–89%.—Evelyn Byer.

            Blanchard, J.L., Jennings, S., Holmes, R., Harle, J., Merino, G., Allen, J.I., Holt, J., Dulvy, N.K., Barange, M., 2012. Potential consequences of climate change for primary production and fish production in large marine ecosystems. Philosophical Transactions of the Royal Society B: Biological Sciences 367, 2979–2989.

Corals Chemically Cue Mutualistic Fishes to Remove Competing Seaweeds

Coral reefs, some of Earth’s most important and fascinating ecosystems, are in global decline—coral cover in has declined nearly 80 percent in the Caribbean and nearly 50 percent in Australia’s Great Barrier Reef. Branching corals such as Acroporids are essential to the growth of coral reefs because they provide topographic complexity, among which many reef species depend. Herbivorous fishes also play a key role in coral reef ecosystems by gnawing on competing algae and facilitating the colonization and growth of new corals after disturbances such as cyclones or disease. Dixson and Hay (2012) show that symbiotic gobies defend the common coral Acropora nasuta by removing allelopathic alga. The process is mediated by chemical signals and cues and may be disrupted or reversed by changes in ocean environment such as pH. Results of this study are not only interesting, but also present the first example of a species chemically cuing consumers to remove competitors.—Kelsey Waite

Dixson, D.L., Hay, M.E., 2012. Corals Chemically Cue Mutualistic Fishes to Remove Competing Seaweeds. Science 338, 804–807.

Exploring the Mechanism Behind Nematode Resistance in Soybean Plants

Soybean crops are becoming increasingly important throughout the world as a source of renewable oil as well as protein. However, they are also a crop that poses many great challenges during production. Perhaps the most destructive of these, a pest called the cyst nematode (Heterodera glycines Ichinohe), has been controlled using resistant soybean plants for many years. However, very little is known about the actual mechanism behind this resistance, and new understanding is desperately needed as old resistant strains of soybean lose their effectiveness. Liu et al. (2012) set out to clone the specific gene that provides resistance to cyst nematodes, and find what proteins it produces to accomplish this feat. The researchers used complicated methods to isolate a gene within the Rhg4 (resistance to Heterodera glycines 4) section of soybean DNA as the gene of interest, and determine that it is responsible for the production of an enzyme that interconverts serine and glycine, two different amino acids. In the future, this knowledge will lead to genetically modified soybean strains and increased production.—Chad Redman

            Liu, S., Kandoth, P. K., Warren, S. D., Yeckel, G., Heinz, R., Alden, J., Yang, C., Jamai1, A., El-Mellouki, T., Juvale, P. S., Hill, J., Baum, T. J., Cianzio, S., Whitham, S. A., Korkin, D., Mitchum, M. G., Meksem, K., 2012. A Soybean Cyst Nematode Resistance Gene Points to a New Mechanism of Plant Resistance to Pathogens. Nature 492, 256–262.