TY - JOUR
T1 - Retranslocation of shoot nitrogen to rhizomes and roots in prairie grasses may limit loss of N to grazing and fire during drought
AU - Heckathorn, S. A.
AU - Delucia, E. H.
PY - 1996/6
Y1 - 1996/6
N2 - 1. It has previously been shown that perennial C4 grasses of tallgrass prairie retranslocate up to 30% of shoot nitrogen (N) to rhizomes and roots in response to water stress and that retranslocation contributes to drought-related decreases in shoot N concentration and photosynthetic capacity, resulting in decreased post-drought carbon gain for 1-2 weeks. 2. In this paper the following hypothesis is tested: under N-limited conditions, the benefits of retranslocation may include limiting loss of shoot N to grazing (or fire) during drought, resulting in increased end-of-season whole-plant biomass, N content, and reproduction. All shoot tissue was removed from young N-limited plants either before or after drought, thereby preventing or allowing the opportunity for retranslocation, and the effects of each clipping treatment on biomass and N content after flowering and senescence were determined. 3. In Spartina pectinata, a mesic species that remobilizes 20-30% of shoot N during drought, plants clipped before drought (no retranslocation) had decreased biomass, N content, and tiller (but not seed) production relative to plants clipped after drought. In contrast, Schizachyrium scoparium, a xeric species that retranslocates little shoot N, exhibited decreased biomass, N content, and tiller and seed production in plants clipped after drought: the result of growth-related increases in total shoot N during drought, and thus greater N loss in plants clipped after drought. Time of clipping had no effect on Andropogon gerardii, a species of intermediate drought tolerance that retranslocates ca. 10% of shoot N during drought. 4. These results support the hypothesis that drought-induced shoot N retranslocation to below-ground tissues represents a trade-off between N protection and post-drought carbon assimilation in prairie grasses.
AB - 1. It has previously been shown that perennial C4 grasses of tallgrass prairie retranslocate up to 30% of shoot nitrogen (N) to rhizomes and roots in response to water stress and that retranslocation contributes to drought-related decreases in shoot N concentration and photosynthetic capacity, resulting in decreased post-drought carbon gain for 1-2 weeks. 2. In this paper the following hypothesis is tested: under N-limited conditions, the benefits of retranslocation may include limiting loss of shoot N to grazing (or fire) during drought, resulting in increased end-of-season whole-plant biomass, N content, and reproduction. All shoot tissue was removed from young N-limited plants either before or after drought, thereby preventing or allowing the opportunity for retranslocation, and the effects of each clipping treatment on biomass and N content after flowering and senescence were determined. 3. In Spartina pectinata, a mesic species that remobilizes 20-30% of shoot N during drought, plants clipped before drought (no retranslocation) had decreased biomass, N content, and tiller (but not seed) production relative to plants clipped after drought. In contrast, Schizachyrium scoparium, a xeric species that retranslocates little shoot N, exhibited decreased biomass, N content, and tiller and seed production in plants clipped after drought: the result of growth-related increases in total shoot N during drought, and thus greater N loss in plants clipped after drought. Time of clipping had no effect on Andropogon gerardii, a species of intermediate drought tolerance that retranslocates ca. 10% of shoot N during drought. 4. These results support the hypothesis that drought-induced shoot N retranslocation to below-ground tissues represents a trade-off between N protection and post-drought carbon assimilation in prairie grasses.
KW - Nutrients
KW - remobilization
KW - tallgrass prairie
KW - water stress
UR - http://www.scopus.com/inward/record.url?scp=0030304893&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0030304893&partnerID=8YFLogxK
U2 - 10.2307/2390289
DO - 10.2307/2390289
M3 - Article
AN - SCOPUS:0030304893
SN - 0269-8463
VL - 10
SP - 396
EP - 400
JO - Functional Ecology
JF - Functional Ecology
IS - 3
ER -