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Title: Does elevated CO2 alter silica uptake in trees?

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, longterm 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, elevatedmore » 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.« less
 [1] ;  [1] ;  [2] ;  [1]
  1. Boston Univ., MA (United States)
  2. The Ecosystems Center, Woods Hole, MA (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Frontiers in Plant Science
Additional Journal Information:
Journal Volume: 5; Journal ID: ISSN 1664-462X
Frontiers Research Foundation
Research Org:
Associated Universities, Inc., Washington, DC (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); Sloan Foundation, New York, NY (United States); National Institute for Global Environmental Change (NIGEC), New Orleans, LA (United States); Univ. of Alabama, Birmingham, AL (United States). Southeast Regional Center (SERC)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES elevated CO2; silicon; forest Si uptake; terrestrial Si pump; active Si accumulation; Si cycling