Finzi Adrien C.

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Adrien C.

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Intentional versus unintentional nitrogen use in the United States : trends, efficiency and implications

2012-10-13 , Houlton, Benjamin Z. , Boyer, Elizabeth , Finzi, Adrien C. , Galloway, James , Leach, Allison , Liptzin, Daniel , Melillo, Jerry M. , Rosenstock, Todd S. , Sobota, Daniel J. , Townsend, Alan R.

Human actions have both intentionally and unintentionally altered the global economy of nitrogen (N), with both positive and negative consequences for human health and welfare, the environment and climate change. Here we examine long-term trends in reactive N (Nr) creation and efficiencies of Nr use within the continental US. We estimate that human actions in the US have increased Nr inputs by at least ~5 times compared to pre-industrial conditions. Whereas N2 fixation as a by-product of fossil fuel combustion accounted for ~1/4 of Nr inputs from the 1970s to 2000 (or ~7 Tg N year−1), this value has dropped substantially since then (to <5 Tg N year−1), owing to Clean Air Act amendments. As of 2007, national N use efficiency (NUE) of all combined N inputs was equal to ~40 %. This value increases to 55 % when considering intentional N inputs alone, with food, industrial goods, fuel and fiber production accounting for the largest Nr sinks, respectively. We estimate that 66 % of the N lost during the production of goods and services enters the air (as NO x , NH3, N2O and N2), with the remaining 34 % lost to various waterways. These Nr losses contribute to smog formation, acid rain, eutrophication, biodiversity declines and climate change. Hence we argue that an improved national NUE would: (i) benefit the US economy on the production side; (ii) reduce social damage costs; and (iii) help avoid some major climate change risks in the future.

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Does elevated CO2 alter silica uptake in trees?

2015-01-13 , Fulweiler, Robinson W. , Maguire, Timothy J. , Carey, Joanna C. , Finzi, Adrien C.

Human activities have greatly altered global carbon (C) and Nitrogen (N) cycling. In fact, atmospheric concentrations of carbon dioxide (CO2) have increased 40% over the last century and the amount of N cycling in the biosphere has more than doubled. In an effort to understand how plants will respond to continued global CO2 fertilization, long-term free-air CO2 enrichment experiments have been conducted at sites around the globe. Here we examine how atmospheric CO2 enrichment and N fertilization affects the uptake of silicon (Si) in the Duke Forest, North Carolina, a stand dominated by Pinus taeda (loblolly pine), and five hardwood species. Specifically, we measured foliar biogenic silica concentrations in five deciduous and one coniferous species across three treatments: CO2 enrichment, N enrichment, and N and CO2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO2, N fertilization, or combined elevated CO2 and N fertilization. However, two-thirds of the tree species studied here have Si foliar concentrations greater than well-known Si accumulators, such as grasses. Based on net primary production values and aboveground Si concentrations in these trees, we calculated forest Si uptake rates under control and elevated CO2 concentrations. Due largely to increased primary production, elevated CO2 enhanced the magnitude of Si uptake between 20 and 26%, likely intensifying the terrestrial silica pump. This uptake of Si by forests has important implications for Si export from terrestrial systems, with the potential to impact C sequestration and higher trophic levels in downstream ecosystems.

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Research frontiers in the analysis of coupled biogeochemical cycles

2011-02 , Finzi, Adrien C. , Cole, Jonathan J. , Doney, Scott C. , Holland, Elisabeth A. , Jackson, Robert B.

The analysis of coupled biogeochemical cycles (CBCs) addresses the scientific basis for some of today's major environmental problems. Drawing from information presented at a series of sessions on CBCs held at the 2009 Annual Meeting of the Ecological Society of America and from the research community's expertise, we identify several principal research themes that justify action and investment. Critical areas for research include: coupling of major element cycles to less studied yet equally important trace element cycles; analyzing CBCs across ecosystem boundaries; integrating experimental results into regional- and global-scale models; and expanding the analysis of human interactions with CBCs arising from human population growth, urbanization, and geoengineering. To advance the current understanding of CBCs and to address the environmental challenges of the 21st century, scientists must maintain and synthesize data from existing observational and experimental networks, develop new instrumentation networks, and adopt emerging technologies.