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Global separation of plant transpiration from groundwater and streamflow
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Current land surface models assume that groundwater, streamflow and plant transpiration are all sourced and mediated by the same well mixed water reservoir—the soil. However, recent work in Oregon1 and Mexico2 has shown evidence of ecohydrological sepa- ration, whereby different subsurface compartmentalized pools of water supply either plant transpiration fluxes or the combined fluxes of groundwater and streamflow. These findings have not yet been widely tested. Here we use hydrogen and oxygen isotopic data (2H/1H (d2H) and 18O/16O (d18O)) from 47 globally distrib- uted sites to show that ecohydrological separation is widespread across different biomes. Precipitation, stream water and ground- water from each site plot approximately along the d2H/d18O slope of local precipitation inputs. But soil and plant xylem waters extracted from the 47 sites all plot below the local stream water and groundwater on the meteoric water line, suggesting that plants use soil water that does not itself contribute to groundwater recharge or streamflow. Our results further show that, at 80% of the sites, the precipitation that supplies groundwater recharge and streamflow is different from the water that supplies parts of soil water recharge and plant transpiration. The ubiquity of subsurface water compartmentalization found here, and the segregation of storm types relative to hydrological and ecological fluxes, may be used to improve numerical simulations of runoff generation, stream water transit time and evaporation–transpiration partitioning. Future land surface model parameterizations should be closely examined for how vegetation, groundwater recharge and streamflow are assumed to be coupled.
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Human mining activity across the ages determines the genetic structure of modern brown trout (Salmo trutta L.) populations
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Humans have exploited the earth’s metal resources for thousands of years leaving behind a legacy of toxic metal contamination and poor water quality. The southwest of England provides a well-defined example, with a rich history of metal mining dating to the Bronze Age. Mine water washout continues to negatively impact water quality across the region where brown trout (Salmo trutta L.) populations exist in both metal-impacted and relatively clean rivers. We used micro- satellites to assess the genetic impact of mining practices on trout populations in this region. Our analyses demonstrated that metal-impacted trout populations have low genetic diversity and have experienced severe population declines. Metal-river trout populations are genetically distinct from clean-river populations, and also from one another, despite being geographically proximate. Using approximate Bayesian computation (ABC), we dated the origins of these genetic patterns to periods of intensive mining activity. The historical split of contemporary metal-impacted populations from clean-river fish dated to the Medieval period. Moreover, we observed two distinct genetic populations of trout within a single catchment and dated their divergence to the Industrial Revolution. Our investigation thus provides an evaluation of contemporary population genetics in showing how human-altered landscapes can change the genetic makeup of a species.
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Hydrologic Units within the Tennessee River Basin
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Unit name and total area (square miles) for 2, 4, 6, and 8 digit hydrologic units within the Tennessee River System.
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Increasing Northern Hemisphere water deficit
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A monthly water-balance model is used with CRUTS3.1 gridded monthly precip- itation and potential evapotranspiration (PET) data to examine changes in global water deficit (PET minus actual evapotranspiration) for the Northern Hemisphere (NH) for the years 1905 through 2009. Results show that NH deficit increased dramatically near the year 2000 during both the cool (October through March) and warm (April through September) seasons. The increase in water deficit near 2000 coincides with a substantial increase in NH temperature and PET. The most pronounced increases in deficit occurred for the latitudinal band from 0 to 40°N. These results indicate that global warming has increased the water deficit in the NH and that the increase since 2000 is unprecedented for the 1905 through 2009 period. Additionally, coincident with the increase in deficit near 2000, mean NH runoff also increased due to increases in P. We explain the apparent contradiction of concurrent increases in deficit and increases in runoff.
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Mapping tree density at a global scale
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The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.
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Medieval warming initiated exceptionally large wildfire outbreaks in the Rocky Mountains
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Many of the largest wildfires in US history burned in recent decades, and climate change explains much of the increase in area burned. The frequency of extreme wildfire weather will increase with continued warming, but many uncertainties still exist about future fire regimes, including how the risk of large fires will persist as vegetation changes. Past fire-climate relationships provide an opportunity to constrain the related uncertainties, and reveal widespread burn- ing across large regions of western North America during past warm intervals. Whether such episodes also burned large portions of individual landscapes has been difficult to determine, however, because uncertainties with the ages of past fires and limited spatial resolution often prohibit specific estimates of past area burned. Accounting for these challenges in a subalpine landscape in Colorado, we estimated century-scale fire synchroneity across 12 lake- sediment charcoal records spanning the past 2,000 y. The percent- age of sites burned only deviated from the historic range of vari- ability during the Medieval Climate Anomaly (MCA) between 1,200 and 850 y B.P., when temperatures were similar to recent decades. Between 1,130 and 1,030 y B.P., 83% (median estimate) of our sites burned when temperatures increased ∼0.5 °C relative to the preceding centuries. Lake-based fire rotation during the MCA decreased to an estimated 120 y, representing a 260% higher rate of burning than during the period of dendroecological sampling (360 to −60 y B.P.). Increased burning, however, did not persist throughout the MCA. Burning declined abruptly before temperatures cooled, indicating possible fuel limitations to continued burning.
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Missouri Department of Conservation
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Our work began in 1937, when citizen-led efforts created the Department of Conservation to restore, conserve and regulate Missouri's over-stressed fisheries, forests and wildlife populations. During our first 40 years, hunting, fishing, and trapping permits provided most of our funding, but in 1976 an expanded program, the "Design for Conservation," was passed to set aside one-eighth of one percent sales tax directly to the agency. That consistent funding, plus a strong, non-political structure and very supportive public helped make Missouri a national leader in conservation. Today we continue our legacy of protecting our state's wild resources and helping Missourians connect with their natural heritage. Our goal is to sustain diverse, healthy plant and animal communities — well into the future.
The Missouri Department of Conservation administers more than 975,000 acres located throughout the state. About 63 percent, or 615,000 acres, are forested.
The forest land occurs on a wide variety of sites and, as a result, there is a broad diversity of plant and animal communities present. Oak and hickory are the most common tree species, but other important species are also found, such as shortleaf pine, eastern red cedar, walnut, ash and cottonwood.
State forest land provides a variety of environmental benefits including wildlife habitat, outdoor recreation, watershed protection, scenic beauty and wood products.
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Mountain True
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MountainTrue champions resilient forests, clean waters, and healthy communities in the Southern Blue Ridge.
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Norwalk River Watershed Association
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The Norwalk River Watershed Association, incorporated in 1996, is a nonprofit membership organization whose mission is to improve the water quality and fish and wildlife habitats of the 40,000-acre Norwalk River watershed; to restore the riverbanks, meadows and forests through invasive plant abatement and promotion of native species; to encourage recreational use of the river, the surrounding open space and its trails; and to promote research, legislative advocacy, education, cooperation, and action on the part of the stakeholders in the seven watershed towns in CT (Ridgefield, Redding, Wilton, New Canaan, Weston, and Norwalk) and NY (Lewisboro).
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Ohio Department of Natural Resources Division of Coastal Management
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The Office of Coastal Management protects and restores the resources of Ohio’s Lake Erie coastline and watershed.
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