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  • Earth Resources and Remote Sensing  (1)
  • Elemental transport  (1)
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  • 1
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    Relationship Between Ecosystem Productivity and Photosynthetically Active Radiation for Northern Peatlands (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-08-17
    Description: We analyzed the relationship between net ecosystem exchange of carbon dioxide (NEE) and irradiance (as photosynthetic photon flux density or PPFD), using published and unpublished data that have been collected during midgrowing season for carbon balance studies at seven peatlands in North America and Europe, NEE measurements included both eddy-correlation tower and clear, static chamber methods, which gave very similar results. Data were analyzed by site, as aggregated data sets by peatland type (bog, poor fen, rich fen, and all fens) and as a single aggregated data set for all peatlands. In all cases, a fit with a rectangular hyperbola (NEE = alpha PPFD P(sub max)/(alpha PPFD + P(sub max) + R) better described the NEE-PPFD relationship than did a linear fit (NEE = beta PPFD + R). Poor and rich fens generally had similar NEE-PPFD relationships, while bogs had lower respiration rates (R = -2.0 micro mol m(exp -2) s(exp -1) for bogs and -2.7 micro mol m(exp -2) s(exp -1)) for fens) and lower NEE at moderate and high light levels (P(sub max)= 5.2 micro mol m(exp -2) s(exp -1) for bogs and 10.8 micro mol m(exp -2) s(exp -1) for fens). As a single class, northern peatlands had much smaller ecosystem respiration (R = -2.4 micro mol m(exp -2) s(exp -1)) and NEE rates (alpha = 0.020 and P(sub max)= 9.2 micro mol m(exp -2) s(exp -1)) than the upland ecosystems (closed canopy forest, grassland, and cropland). Despite this low productivity, northern peatland soil carbon pools are generally 5-50 times larger than upland ecosystems because of slow rates of decomposition caused by litter quality and anaerobic, cold soils.
    Keywords: Earth Resources and Remote Sensing
    Type: Paper 97GB03367 , Global Biogeochemical Cycles (ISSN 0886-6236); 12; 1; 115-126
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
    Electronic Resource
    Electronic Resource
    The biogeochemistry of pristine, headwater Precambrian shield watersheds: an analysis of material transport within a heterogeneous landscape (1993)
    Springer
    Biodegradation 22 (1993), S. 37-79 
    Details
    ISSN: 1572-9729
    Keywords: Elemental transport ; hydrologic pathways ; spatial heterogeneity ; Precambrian shield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The hydrology and elemental transport within five low order Precambrian shield catchments was investigated during 1988–90. Catchments were subdivided and instrumented to examine the vertical and horizontal fluxes of elements within and between two distinct landscape types: open, lichen-covered bedrock outcrops and patches of conifer forest. The dominant hydrologic pathways were Horton overland flow in the lichen-bedrock areas and shallow subsurface flow through organic rich LFH (forest floor) and Ah soil horizons in the forested areas. Annual runoff coefficients ranged from 0.3 to 0.7. Runoff chemistry was acidic (pH 4.01–4.72), with organic anion equivalents (RCOO-), comprising 60 and 69% of the anion charge total for bedrock and forest runoff, respectively. Forested plots exported more H+ (2.6x), DOC (1.4x), Al (1.6x) and Fe (1.8x) and less N (0.40x), P (0.13x), particulate C (0.08x), Ca2+ (0.38x), Mg2+ (0.83x), Na+ (0.85x) and K+ (0.32x) per unit area than the bedrock-lichen plots. The catchments exhibited a net export of H+ (34), Mg2+ (24), Na+ (20), K+ (4) (units in eq ha-1 yr-1) and C (16), Si (5.6), Al (1.6) and Fe (0.47) (units kg ha-1 yr-1). The catchments retained N (5.66), P (0.08), Mn (0.03) (units kg ha-1 yr-1), and Ca2+ (37), and Cl- (3) (units eq ha-1 yr-1). The strong retention of Ca2+ within the treed soil islands resulted in extremely low export rates of base cations (-15 to 38 eq ha-1 yr-1). The spatial distribution and hydrologic and biogeochemical linkages associated with each landscape unit interact to control element transport within the study catchments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002756
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    Paper (German National Licenses)
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