Improving understanding of valley-wide stream chemistry

A geostatistical approach for studying environmental conditions in stream networks and landscapes has been successfully applied at a valley-wide scale to assess headwater stream chemistry at high resolution, revealing unexpected patterns in natural chemical components.”Headwater streams make up the majority of stream and river length in watersheds, affecting regional water quality,” said Assistant Professor Kevin J. McGuire, associate director of the Virginia Water Resources Research Center in Virginia Tech’s College of Natural Resources and Environment. “However, the actual patterns and causes of variation of water quality in headwater streams are often unknown.””Understanding the chemistry of these streams at a finer scale could help to identify factors impairing water quality and help us protect aquatic ecosystems,” said Gene E. Likens, president emeritus and distinguished senior scientist emeritus with the Cary Institute of Ecosystem Studies and the University of Connecticut.Results of the study that used a new statistical tool to describe spatial patterns of water chemistry in stream networks are published in the April 21 issue of the Proceedings of the National Academies of Science by a team of ecosystem scientists, including McGuire and Likens.The data used in the new analysis consist of 664 water samples collected every 300 feet throughout all 32 tributaries of the 14-square-mile Hubbard Brook Valley in New Hampshire. The chemistry results were originally reported in 2006 in the journal Biogeochemistry by Likens and Donald C. Buso, manager of field research with the Cary Institute.McGuire and other members of the National Science Foundation’s Long-Term Ecological Research team at the Hubbard Brook Ecosystem Study decided that the huge, high-resolution dataset was ideal for a new statistical approach that examines how water flows both within the stream network and across the landscape.”The goal was to visualize patterns that no one has been able to quantify before now and describe how they vary within headwater stream networks,” said McGuire. “Some chemical constituents vary at a fine scale, that is patterns of chemical change occur over very short distances, for example several hundred feet, but some constituents vary over much larger scales, for example miles. Several chemical constituents that we examined even varied at multiple scales suggesting that nested processes within streams and across the landscape influence the chemistry of stream networks.””The different spatial relationships permit the examination of patterns controlled by landscape versus stream network processes,” the article reports. Straight-line and unconnected network spatial relationships indicate landscape influences, such as soil, geology, and vegetation controls of water chemistry, for instance. In contrast, flow-connected relationships provide information on processes affected within the flowing streams.The researchers are very familiar with the Hubbard Brook Valley and could point to the varying influences of the geology and distinct soil types, including areas of shallow acidic organic-rich soils.The findings revealed by the analysis technique showed how chemistry patterns vary across landscapes with two scales of variation, one around 1,500 feet and another at about 4 miles. …

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National U.S. study reveals how urban lawn care habits vary

What do people living in Boston, Baltimore, Miami, Minneapolis-St. Paul, Phoenix, and Los Angeles have in common? From coast to coast, prairie to desert — residential lawns reign.But, according to a new study in the Proceedings of the National Academy of Sciences, beneath this sea of green lie unexpected differences in fertilization and irrigation practices. Understanding urban lawn care is vital to sustainability planning, more than 80% of Americans live in cities and their suburbs, and these numbers continue to grow.The study was undertaken to test “the homogenization hypothesis.” Peter Groffman, a scientist at the Cary Institute of Ecosystem Studies and one of the paper’s authors explains, “Neighborhoods in very different parts of the country look remarkably alike, from lawns and roads to water features. This study is the first to test if urbanization produces similar land management behaviors, independent of the local environment.”Some 9,500 residents in the six study cities were queried about their lawn care habits. The research team, led by Colin Polsky of Clark University and colleagues at 10 other institutions, took into account differences in climate and neighborhood socioeconomics, both within and between cities. A focus was put on fertilization and irrigation, practices with potentially hefty environmental price tags.Fertilizer is rich in nitrogen and phosphorus. This stimulates lawn growth, but when fertilizer washes into waterways, it causes algal blooms that degrade water quality and rob oxygen from fish and other aquatic life. According to the Environmental Protection Agency, landscape irrigation accounts for nearly one-third of residential water use nationwide.Some 79% of surveyed residents watered their lawns and 64% applied fertilizer. Groffman comments, “These numbers are important when we bear in mind that lawns cover more land in the United States than any other irrigated crop. …

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Environmental policy: Tallying the wins and losses of policy

July 1, 2013 — In the past decade, China has sunk some impressive numbers to preserve its forests, but until now, there hasn’t been much data to give a true picture of how it has simultaneously affected both the people and the environment.Michigan State University, partnered with the Chinese Academy of Sciences, has capitalized on their long history of research in the Wolong Nature Reserve to get a complete picture of the environmental and socioeconomic effects of payments for ecosystem services programs.”Performance and prospects of payments for ecosystem services programs: evidence from China” has been published in the Journal of Environmental Management. In it, Wu Yang, a doctoral student in Michigan State University’s Center for Systems Integration and Sustainability and center director Jianguo “Jack” Liu, the Rachel Carson Chair in Sustainability, outline the wins and losses in one of the world’s richest areas of biodiversity, and home to the endangered giant pandas.China’s tally: $15 billion to ban logging encourage new forests; $32 billion to persuade 32 million rural households to return 8.8 million hectares of cropland back to forest.The group examined both the people and the environment from as big a picture as trends of the forest from decades of land cover maps, to surveying individual households to understand how their behaviors changed as policies were introduced. Payments for ecosystem services programs — programs in which people were given incentives to change their behavior so the forest around them could recover — have been an enormous effort in China and worldwide.The work found that China’s offering people incentives to change how they live to boost the environment did benefit the forest and the environment — but not without a toll on the people who live there.The article emphasizes the importance of integrating local conditions and understanding underlying mechanisms to enhance the performance of payments for ecosystem services programs. The article also notes that understanding some of the impacts raises questions for future policy — about whether such policies could be made more efficient, is it ethical to make conservation gains at the cost of people’s livelihoods, cultural identity and other issues.In addition to Yang and Liu, the article was written by CSIS members Wei Liu, a former doctoral student; assistant professor Andrés Viña, research associate Junyan Luo and former doctoral student Guangming He. Also contributing were Zhiyun Ouyang from the Chinese Academy of Science and Hemin Zhang of China’s Center for Giant Panda Research and Conservation.The work was supported by the National Science Foundation, NASA,Michigan State University’s Environmental Science and Policy Program, and Graduate Office.

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Changing ocean temperatures, circulation patterns affecting young Atlantic cod food supply

June 20, 2013 — Changing ocean water temperatures and circulation patterns have profoundly affected key Northeast U.S. Continental Shelf zooplankton species in recent decades, and may be influencing the recovery of Atlantic cod and other fish stocks in the region.NOAA researcher Kevin Friedland and colleagues looked at the distribution and abundance of important zooplankton species, sea surface water temperatures, and cod abundance. They found that zooplankton species critical for the survival of Atlantic cod larvae have declined in abundance in the same areas where Atlantic cod stocks have struggled to rebuild after an extended period of overfishing.”Temperature is a governing factor in the growth, reproduction and distribution of marine organisms. Shifting temperature distributions, whether triggered by natural or human factors, can cause the redistribution of plankton communities on regional and basin-wide scales,” said Friedland, lead author on the study and a scientist at NOAA’s Northeast Fisheries Science Center (NEFSC).The change in thermal habitats has had biological consequences on multiple levels in the food chain, according to the study in press in the journal Progress in Oceanography.”The geographic and depth distributions of fish and shellfish populations can also change based on their preferred thermal habitats. Future changes in thermal conditions are expected to lead to further shifts in the distributional ranges of species by, in many cases, the loss and gain of local populations,” said Friedland.Friedland and his colleagues found that ocean water temperatures of the Northeast Continental Shelf have increased in recent decades, but these changes have not been uniform over the entire ecosystem. Warm water habitats (16 to 27 C, 60 to 80 F) have increased and cool water habitats (5 to 15 C, 41 to 59 F), historically the core habitats in the ecosystem, have declined; however, the coldest habitats in the ecosystem (1-4 C, 34-39 F) have either stayed the same or increased slightly during the study period 1982-2011. This discontinuity is attributed to changes in circulation in the northern Gulf of Maine associated with the Labrador Current.Atlantic cod off the Northeast U.S. are managed as two stock units, the more northerly in the Gulf of Maine and the more southerly on and around Georges Bank. There are upward of ten known spawning populations within these two stocks, and the very young fish that they produce are found in specific larval development areas. Two zooplankton species that serve as food for Atlantic cod (Gadus morhua) larvae are Pseudocalanus spp, and Centropages typicus. …

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Predators affect the carbon cycle, study shows

June 17, 2013 — A new study shows that the predator-prey relationship can affect the flow of carbon through an ecosystem. This previously unmeasured influence on the environment may offer a new way of looking at biodiversity management and carbon storage for climate change.The study, conducted by researchers at the Yale School of Forestry & Environmental Studies, comes out this week in the Proceedings of the National Academy of Sciences. It looks at the relationship between grasshoppers and spiders — herbivores and predators in the study’s food chain — and how it affects the movement of carbon through a grassland ecosystem. Carbon, the basic building block of all organic tissue, moves through the food chain at varying speeds depending on whether it’s being consumed or being stored in the bodies of plants. However, this pathway is seldom looked at in terms of specific animal responses like fear from predation.”We’re discovering that predators are having important effects on shaping the make-up of ecosystems,” says Dr. Oswald Schmitz, professor of ecology and one of the co-authors of the study. “But we’ve not really spent a lot of time measuring how that translates into other functions like nutrient cycling and recycling.”The researchers manipulated the food chains of grassland ecosystem to see how the levels of carbon would change over time. Dr. Schmitz and his team created several controlled ecosystems: some that contained only native grasses and herbs, others that had plants and an herbivore grasshopper, and some others that had plants and herbivores along with a carnivore spider species — all three tiers of the food chain. In addition, a form of traceable carbon dioxide was injected into sample cages covered with Plexiglas, which allowed the team to track the carbon levels by periodically taking leaf, root, and dead animal samples.The study found that the presence of spiders drove up the rate of carbon uptake by the plants by about 1.4 times more than when just grasshoppers were present and by 1.2 more times than when no animals were present. …

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‘Cold snap’ 116 million years ago triggered marine ecosystem crisis

June 16, 2013 — A “cold snap” 116 million years ago triggered a similar marine ecosystem crisis to the ones witnessed in the past as a result of global warming, according to research published in Nature Geoscience.The international study involving experts from the universities of Newcastle, UK, Cologne, Frankfurt and GEOMAR-Kiel, confirms the link between global cooling and a crash in the marine ecosystem during the mid-Cretaceous greenhouse period.It also quantifies for the first time the amplitude and duration of the temperature change. Analysing the geochemistry and micropaleontology of a marine sediment core taken from the North Atlantic Ocean, the team show that a global temperature drop of up to 5oC resulted in a major shift in the global carbon cycle over a period of 2.5 million years.Occurring during a time of high tectonic activity that drove the breaking up of the super-continent Pangaea, the research explains how the opening and widening of new ocean basins around Africa, South America and Europe created additional space where large amounts of atmospheric CO2 was fixed by photosynthetic organisms like marine algae. The dead organisms were then buried in the sediments on the sea bed, producing organic, carbon rich shale in these new basins, locking away the carbon that was previously in the atmosphere.The result of this massive carbon fixing mechanism was a drop in the levels of atmospheric CO2, reducing the greenhouse effect and lowering global temperature.This period of global cooling came to an end after about 2 million years following the onset of a period of intense local volcanic activity in the Indian Ocean. Producing huge volumes of volcanic gas, carbon that had been removed from the atmosphere when it was locked away in the shale was replaced with CO2 from Earth’s interior, re-instating a greenhouse effect which led to warmer climate and an end to the “cold snap.”The research team highlight in this study how global climate is intrinsically linked to processes taking place in Earth’s interior at million year time scales. These processes can modify ecospace for marine life, driving evolution.Current research efforts tend to concentrate on global warming and the impact that a rise of a few degrees might have on past and present day ecosystems. This study shows that if global temperatures swing the other way by a similar amount, the result can be just as severe, at least for marine life.However, the research team emphasise that the observed changes of the Earth system in the Cretaceous happened over millions of years, rather than decades or centennial, which cannot easily be related to our rapidly changing modern climate conditions.”As always it’s a question of fine balance and scale,” explains Thomas Wagner, Professor of Earth Systems Science at Newcastle University, and one of the leaders of this study.”All earth system processes are operating all the time and at different temporal and spatial scales; but when something upsets the balance — be it a large scale but long term natural phenomenon or a short and massive change to global greenhouse gases due to anthropogenic activity — there are multiple, potential knock-on effects on the whole system.”The trick is to identify and quantify the initial drivers and consequences, which remains an ongoing challenge in climate research.”

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Do parasites upset food web theory?

June 11, 2013 — Parasites comprise a large proportion of the diversity of species in every ecosystem. Despite this, they are rarely included in analyses or models of food webs. If parasites play different roles from other predators and prey, however, their inclusion could fundamentally alter our understanding of how food webs are organized. In a paper published 11 June in the open access journal PLOS Biology, Santa Fe Institute Professor Jennifer Dunne and her team test this assertion and show that including parasites does alter the structure of food webs, but that most changes occur because of an increase in diversity and complexity, rather than from unique characteristics of parasites.”Current food web models and theory were developed with data for free-living species,” said Dunne. “We wanted to understand whether including parasites alters network structure in unique ways, or if observed changes are consistent with the addition of any types of species and links to a food web.”The group of researchers, which included parasitologists and food web ecologists, analyzed highly resolved datasets for seven coastal estuary and marine food webs. They compared three versions of each food web dataset: webs without parasites; webs that included parasites and all of their links to other species; and an intermediate case that included parasites but excluded the “concomitant” links between a predator and the parasites of its prey.The team found that including parasites altered many aspects of network structure, such as the distribution of feeding links per species, the average shortest feeding chain between pairs of species, and the proportion of species that are omnivores or cannibals. But a closer look suggested that most of these changes were generic effects of increasing the overall diversity and complexity of the network, rather than unique effects attributable to the parasites’ roles in food webs.”Our analyses show that in many ways parasites are similar to other species in terms of their effects on food web organization,” said Dunne. However, the team did find two cases where parasites seem to play special roles that alter aspects of food web structure. One case is when a parasite is eaten along with its host. “The physical intimacy between a parasite and its host is not found as frequently between free-living predators and prey,” Dunne said. …

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Simplified solutions to deforestation ineffective in long run

May 29, 2013 — Deforestation is the second largest source of CO2 emissions after consumption of fossil fuels. So-called PES programmes, where landowners are paid to replant or protect forests, have been promoted as a way to reduce deforestation. However, the effectiveness of the programmes has been questioned, and new research from the School of Business, Economics and Law at the University of Gothenburg, Sweden, points to potential negative long-term effects and a need for broader guidelines and policies.

PES programmes have been promoted as a cost-effective tool to combat climate change. However, the rather limited documentation on the effectiveness of the programmes is discouraging.

‘Human behaviour is not always predictable, and short-term positive effects may turn to negative effects in the long term,’ says Anna Nordén, economics researcher at the School of Business, Economics and Law, University of Gothenburg.

In her recently presented doctoral thesis titled Essays on Behavioral Economics and Policies for Provision of Ecosystem Services, Nordén explores the weaknesses of PES programmes and the importance of complementing them with additional measures.

The established climate targets make the measurability of PES programmes appealing — it is tempting to point to results by quantifying forests that would probably have been cut down in the absence of PES programmes. Paying landowners for abstaining from deforestation is considered the most effective programme design. However, this strategy implies that those who are already maintaining their forests are not rewarded. Nordén conducted experiments to identify the consequences of such programmes, and found that those who are already displaying the desired behaviour tend to eventually lose their willingness to protect their forests.

‘The net effect of these programmes may be negligible, meaning that the money spent may not do much to reduce emissions and combat climate change,’ says Nordén, who calls for better awareness of the effects of different reward systems.

Nordén also studied what motivates landowners to participate in PES programmes and how they react to the size and type of the payments they receive. In a study in Costa Rica, landowners were offered either cash or education.

‘Both payment types stimulated participation, but when we looked at long-term participation — more than five years — cash had a greater effect. And the more cash the landowners were offered, the more motivated they were to participate in the programme. They did not respond the same to more education.’

Yet cash payments can also have negative effects on the climate. Nordén gives an example:

‘When a poor landowner is paid in cash, he may become able to pay somebody to cut down his forest.’

Nordén is critical to the narrow focus of climate negotiations on PES programmes.

‘It seems naive to believe that just one policy will reduce deforestation. My research points to the importance of complementing the programmes with other tools and measures, and of paying better attention to long-term effects.’

The thesis was presented on 24 May 2013 Thesis title: Essays on Behavioral Economics and Policies for Provision of Ecosystem Services

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