Waterlogging and fire impacts on nitrogen availability and utilization in a subtropical wet heathland (wallum)

Schmidt, S and Stewart, GR (1997) Waterlogging and fire impacts on nitrogen availability and utilization in a subtropical wet heathland (wallum). Plant Cell And Environment, 20 10: 1231-1241. doi:10.1046/j.1365-3040.1997.d01-20.x


Author Schmidt, S
Stewart, GR
Title Waterlogging and fire impacts on nitrogen availability and utilization in a subtropical wet heathland (wallum)
Journal name Plant Cell And Environment   Check publisher's open access policy
ISSN 0140-7791
Publication date 1997-01-01
Sub-type Article (original research)
DOI 10.1046/j.1365-3040.1997.d01-20.x
Volume 20
Issue 10
Start page 1231
End page 1241
Total pages 11
Language eng
Abstract Protein, amino acids and ammonium were the main forms of soluble soil nitrogen in the soil solution of a subtropical heathland (wallum). After fire, soil ammonium and nitrate increased 90- and 60-fold, respectively. Despite this increase in nitrate availability after fire, wallum species exhibited uniformly low nitrate reductase activities and low leaf and xylem nitrate, During waterlogging soil amino acids increased, particularly gamma-aminobutyric acid (GABA) which accounted for over 50% of amino nitrogen. Non-mycorrhizal wallum species were significantly (P < 0.05) N-15-enriched (0.3-4.3 parts per thousand) compared to species with mycorrhizal associations (ericoid-type, ecto-, va-mycorrhizal) which were strongly depleted in N-15 (-6.3 to -1.8 parts per thousand). Lignotubers and roots had delta(15)N signatures similar to that of the leaves of respective species. The exceptions were fine roots of ecto-, ecto/va-, and ericoid type mycorrhizal species which were enriched in N-15 (0.1-2 4 parts per thousand). The delta(15)N signatures of delta(15)N(total soil N) and delta(15)N(soil NH4+) were in the range 3.7-4.5 parts per thousand, whereas delta(15)N(soil NO3-) was significantly (P < 0.05) more enriched in N-15 (9.2-9.8 parts per thousand). It is proposed that there is discrimination against N-15 during transfer of nitrogen from fungal to plant partner. Roots of selected species incorporated nitrogen sources in the order of preference: ammonium > glycine > nitrate. The exception were proteoid roots of Hakea (Proteaceae) which incorporated equal amounts of glycine and ammonium.
Keyword Plant Sciences
Fire
Mycorrhiza
N-15 Natural Abundance
Nitrate Reductase Activity
Nitrogen Sources
Proteoid Roots
Root Specializations
Subtropical Heathland
Wallum
Waterlogging
N-15 Natural-abundance
Nitrate Utilization
Arctic Plants
Amino-acids
Mycorrhizal Associations
Organic Nitrogen
Soil
Ericaceae
Biology
Forest
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Biological Sciences Publications
Ecology Centre Publications
 
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Created: Tue, 14 Aug 2007, 03:01:39 EST