N2 fixation and cycling in Alnus glutinosa, Betula pendula and Fagus sylvatica woodland exposed to free air CO2 enrichment
Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
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Yn: Oecologia, Cyfrol 169, Rhif 2, 18.12.2011, t. 541-52.
Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
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T1 - N2 fixation and cycling in Alnus glutinosa, Betula pendula and Fagus sylvatica woodland exposed to free air CO2 enrichment
AU - Millett, Jonathan
AU - Godbold, Douglas
AU - Smith, Andrew R
AU - Grant, Helen
PY - 2011/12/18
Y1 - 2011/12/18
N2 - We measured the effect of elevated atmospheric CO(2) on atmospheric nitrogen (N(2)) fixation in the tree species Alnus glutinosa growing in monoculture or in mixture with the non-N(2)-fixing tree species Betula pendula and Fagus sylvatica. We addressed the hypotheses that (1) N(2) fixation in A. glutinosa will increase in response to increased atmospheric CO(2) concentrations, when growing in monoculture, (2) the impact of elevated CO(2) on N(2) fixation in A. glutinosa is the same in mixture and in monoculture and (3) the impacts of elevated CO(2) on N cycling will be evident by a decrease in leaf δ(15)N and by the soil-leaf enrichment factor (EF), and that these impacts will not differ between mixed and single species stands. Trees were grown in a forest plantation on former agricultural fields for four growing seasons, after which the trees were on average 3.8 m tall and canopy closure had occurred. Atmospheric CO(2) concentrations were maintained at either ambient or elevated (by 200 ppm) concentrations using a free-air CO(2) enrichment (FACE) system. Leaf δ(15)N was measured and used to estimate the amount (N(dfa)) and proportion (%N(dfa)) of N derived from atmospheric fixation. On average, 62% of the N in A. glutinosa leaves was from fixation. The %N(dfa) and N(dfa) for A. glutinosa trees in monoculture did not increase under elevated CO(2), despite higher growth rates. However, N(2) fixation did increase for trees growing in mixture, despite the absence of significant growth stimulation. There was evidence that fixed N(2) was transferred from A. glutinosa to F. sylvatica and B. pendula, but no evidence that this affected their CO(2) response. The results of this study show that N(2) fixation in A. glutinosa may be higher in a future elevated CO(2) world, but that this effect will only occur where the trees are growing in mixed species stands.
AB - We measured the effect of elevated atmospheric CO(2) on atmospheric nitrogen (N(2)) fixation in the tree species Alnus glutinosa growing in monoculture or in mixture with the non-N(2)-fixing tree species Betula pendula and Fagus sylvatica. We addressed the hypotheses that (1) N(2) fixation in A. glutinosa will increase in response to increased atmospheric CO(2) concentrations, when growing in monoculture, (2) the impact of elevated CO(2) on N(2) fixation in A. glutinosa is the same in mixture and in monoculture and (3) the impacts of elevated CO(2) on N cycling will be evident by a decrease in leaf δ(15)N and by the soil-leaf enrichment factor (EF), and that these impacts will not differ between mixed and single species stands. Trees were grown in a forest plantation on former agricultural fields for four growing seasons, after which the trees were on average 3.8 m tall and canopy closure had occurred. Atmospheric CO(2) concentrations were maintained at either ambient or elevated (by 200 ppm) concentrations using a free-air CO(2) enrichment (FACE) system. Leaf δ(15)N was measured and used to estimate the amount (N(dfa)) and proportion (%N(dfa)) of N derived from atmospheric fixation. On average, 62% of the N in A. glutinosa leaves was from fixation. The %N(dfa) and N(dfa) for A. glutinosa trees in monoculture did not increase under elevated CO(2), despite higher growth rates. However, N(2) fixation did increase for trees growing in mixture, despite the absence of significant growth stimulation. There was evidence that fixed N(2) was transferred from A. glutinosa to F. sylvatica and B. pendula, but no evidence that this affected their CO(2) response. The results of this study show that N(2) fixation in A. glutinosa may be higher in a future elevated CO(2) world, but that this effect will only occur where the trees are growing in mixed species stands.
KW - Air
KW - Alnus/drug effects
KW - Betula/drug effects
KW - Carbon Dioxide/pharmacology
KW - Fagus/drug effects
KW - Nitrogen Fixation
KW - Nitrogen Isotopes/analysis
KW - Plant Leaves/physiology
U2 - 10.1007/s00442-011-2197-4
DO - 10.1007/s00442-011-2197-4
M3 - Article
C2 - 22179329
VL - 169
SP - 541
EP - 552
JO - Oecologia
JF - Oecologia
SN - 0029-8549
IS - 2
ER -