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Title: Does elevated CO 2 alter silica uptake in trees?

Human activities have greatly altered global carbon (C) and Nitrogen (N) cycling. In fact, atmospheric concentrations of carbon dioxide (CO 2) 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 CO 2 fertilization, longterm free-air CO 2 enrichment experiments have been conducted at sites around the globe. Here we examine how atmospheric CO 2 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: CO 2 enrichment, N enrichment, and N and CO 2 enrichment. We found no consistent trends in foliar Si concentration under elevated CO 2, N fertilization, or combined elevated CO 2 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 COmore » 2 concentrations. Due largely to increased primary production, elevated CO 2 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
Authors:
 [1] ;  [1] ;  [2] ;  [1]
  1. Boston Univ., MA (United States)
  2. The Ecosystems Center, Woods Hole, MA (United States)
Publication Date:
Grant/Contract Number:
FG02-97ER25308
Type:
Accepted Manuscript
Journal Name:
Frontiers in Plant Science
Additional Journal Information:
Journal Volume: 5; Journal ID: ISSN 1664-462X
Publisher:
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
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; elevated CO2; silicon; forest Si uptake; terrestrial Si pump; active Si accumulation; Si cycling
OSTI Identifier:
1204502