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Plants convert carbon dioxide into sugars for food during photosynthesis, and this provides food for all animal life. However, photosynthesis is inhibited when a plant’s enzymes use oxygen instead of carbon dioxide. To avoid this use of oxygen, some plants developed a photosynthetic adaptation – called C4 photosynthesis – to concentrate carbon dioxide around the enzymes. While less than 5% of plants use the C4 photosynthetic pathway, they make up ~20% of global terrestrial gross primary productivity. Due to their high productivity, C4 plants have a profound impact on ecosystems, economies, the carbon cycle, and our climate. Corn and sugarcane are both C4 plants, as are foundational western livestock and wildlife...
Fresh water is arguably the most valuable resource on the planet, but human activities threaten freshwater ecosystems. For example, use of synthetic chemicals, such as pesticides, road salts, and nutrients, has led to the ubiquitous contamination of aquatic systems, jeopardizing the integrity of ecological communities. Given the importance biodiversity plays in maintaining ecosystem health and function and the continued decline of freshwater species, it is vital to understand the direct, indirect, and lasting effects of synthetic contaminants on biota in freshwater systems. The majority of our knowledge regarding contaminant effects is comprised of short-term, single-contaminant laboratory toxicity tests that describe...
Advances in new technologies such as remote cameras, noninvasive genetics and bioacoustics provide massive quantities of electronic data. Much work has been done on automated (“machine learning”) methods of classification which produce “sample class designations” (e.g., identification of species or individuals) that are regarded as observed data in ecological models. However, these “data” are actually derived quantities (or synthetic data) and subject to various important sources of bias and error. If the derived quantities are used to make ecological determinations without consideration of these biases, those inferences which inform monitoring, conservation, and management will be flawed. We propose to develop...
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Streamflow is declining in many parts of the United States (US) due to factors including groundwater pumping, land use change, and climate change. Streamflow depletion, a reduction in groundwater discharge to a stream due to human activities such as pumping and/or land use change, tends to evolve slowly and can be entirely invisible for many years to decades. This is because streamflow depletion can be masked by the natural and/or climate change-induced variability in streamflow, and groundwater storage can buffer the impacts on streams. The negative effects on both anthropogenic and ecological systems can evolve over decades or more, and specific causes and potential solutions to these issues are often difficult...
Water in the United States is used for myriad activities on a daily basis, such as for food (irrigation, aquaculture, livestock), energy (thermoelectric power or hydropower generation), and public water supply for domestic, commercial or industrial purposes. Yet, we lack an national accounting of how and where water is used on a temporal scale more frequent than every 5 years, and a spatial scale greater than county level. The “water data drought” in the U.S. and globally is one of the key barriers inhibiting our understanding of how the environment sustains society and how society alters the environment. The world’s best mesoscale water use dataset is the USGS Water-Use report (the so-called “water census”), which...
Drought impacts on terrestrial ecosystems have increased globally in the 21st century, and droughts are expected to become more frequent, extreme, and spatially extensive in the future. Historical site-based observations are inadequate to predict how future extreme water deficits will affect the global terrestrial surface, because future droughts and their impacts may be more extreme than they have been historically and reach well beyond a single ecosystem. This USGS Powell Center working group will conduct the first comprehensive synthesis of ecosystem impacts across a coordinated, globally distributed drought experiment network of over 100 sites that have imposed an extreme multi-year drought. Knowledge about...
Groundwater plays a critical role in the water balance, however the groundwater component of the hydrologic cycle is frequently overlooked at basin scales because it is difficult to observe and quantify. We address this problem through a novel framework that combines existing hydrological models and data sets with groundwater flux estimates across Earth's largest system of lakes; the Laurentian Great Lakes. Aside from serving as a template for combining surface and ground water data and models, the Laurentian Great Lakes recently transitioned from a period characterized by water scarcity (water levels on the lakes were persistently below average from 1998 through 2013) to extreme water abundance (all-time high...
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