TY - JOUR
T1 - Grasses have larger response than shrubs to increased nitrogen availability
T2 - A fertilization experiment in the Patagonian steppe
AU - Yahdjian, Laura
AU - Gherardi, Laureano
AU - Sala, Osvaldo
N1 - Funding Information:
This work was funded by the Agencia Nacional de Promoción Científica y Tecnológica ( PICT 0553 ), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, PIP 132 ), Arizona State University and the Universidad de Buenos Aires (UBACyT). Institutional support was provided by the Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA), and at the field site by the Instituto Nacional de Tecnología Agropecuaria (INTA) that gave permission to use facilities at Río Mayo Experimental Field Station, Chubut. We are grateful to Patricia Araujo, Jennifer Landesman, Ignacio Romero, Florencia Spirito, Germán Wies, G.A Gil, Felipe Cabrera and Lorena Grion for assistance and guidance.
PY - 2014/3
Y1 - 2014/3
N2 - Nitrogen limits plant growth in almost all terrestrial ecosystems, even in low-precipitation ecosystems. Vegetation in arid ecosystems is usually composed of two dominant plant-functional types, grasses and shrubs, which have different rooting and water acquisition patterns. These plant-functional types may respond differently to N availability because they have different strategies to absorb and retranslocate N. We hypothesized that grasses are more N limited than shrubs, and consequently will show higher responses to N addition. To test this hypothesis, we added 50kgNha-1year-1 as NH4NO3 during two years in the Patagonian steppe, Argentina, and we evaluated the responses of aboveground net primary production and N concentration of green leaves of the dominant grass and shrub species. Grass biomass significantly (P=0.007) increased with increased N availability whereas shrub biomass did not change after two years of N addition. Shrubs have higher nitrogen concentration in green leaves than grasses, particularly the leguminous Adesmia volkman n i, and showed no response to N addition whereas foliar N concentration of grasses significantly increased with N fertilization (P<0.05). Grasses may have a larger response to increase N availability than shrubs because they have a more open N economy absorbing up to 30% of their annual requirement from the soil. In contrast, shrubs have a closer N cycle, absorbing between 7 and 16% of their annual N requirement from the soil. Consequently shrubs depend less on soil N availability and are less responsive to increases in soil N.
AB - Nitrogen limits plant growth in almost all terrestrial ecosystems, even in low-precipitation ecosystems. Vegetation in arid ecosystems is usually composed of two dominant plant-functional types, grasses and shrubs, which have different rooting and water acquisition patterns. These plant-functional types may respond differently to N availability because they have different strategies to absorb and retranslocate N. We hypothesized that grasses are more N limited than shrubs, and consequently will show higher responses to N addition. To test this hypothesis, we added 50kgNha-1year-1 as NH4NO3 during two years in the Patagonian steppe, Argentina, and we evaluated the responses of aboveground net primary production and N concentration of green leaves of the dominant grass and shrub species. Grass biomass significantly (P=0.007) increased with increased N availability whereas shrub biomass did not change after two years of N addition. Shrubs have higher nitrogen concentration in green leaves than grasses, particularly the leguminous Adesmia volkman n i, and showed no response to N addition whereas foliar N concentration of grasses significantly increased with N fertilization (P<0.05). Grasses may have a larger response to increase N availability than shrubs because they have a more open N economy absorbing up to 30% of their annual requirement from the soil. In contrast, shrubs have a closer N cycle, absorbing between 7 and 16% of their annual N requirement from the soil. Consequently shrubs depend less on soil N availability and are less responsive to increases in soil N.
KW - Arid ecosystems
KW - Foliar nitrogen
KW - Nitrogen fertilization
KW - Plant functional types
KW - Primary production
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U2 - 10.1016/j.jaridenv.2013.11.002
DO - 10.1016/j.jaridenv.2013.11.002
M3 - Article
AN - SCOPUS:84888878948
SN - 0140-1963
VL - 102
SP - 17
EP - 20
JO - Journal of Arid Environments
JF - Journal of Arid Environments
ER -