
TY  - JOUR
A1  - Lane, Diana R. 
A1  - BassiriRad, Hormoz 
T1  - Differential responses of tallgrass prairie species to nitrogen loading and varying ratios of NO<emph type="8">3</emph><emph type="7">&#8211;</emph> to NH<emph type="8">4</emph><emph type="7">+</emph>
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 2002
VL  - 29
IS  - 10
SP  - 1227
EP  - 1235
KW  - nitrogen deposition, root uptake.
UR  - https://doi.org/10.1071/PP01225 
N2  - Worldwide atmospheric N deposition varies in both quantity and composition of inorganic N forms (NO3&#8211; and NH4+). Many studies designed to assess the potential consequences of N pollution, however, pay little attention to the relative abundance of N forms. We hypothesized that native species with different physiological properties will show varying responses to different forms and amounts of N deposition. Here, we assessed the responses of six herbaceous species native to tallgrass prairies in North America to increased N loading at differing ratios of NO3&#8211; : NH4+. Individual plants of each species were grown for roughly 80 d in a sand culture under field conditions, three N levels (0.1, 1, 3 mM N), and three ratios of NO3&#8211; : NH4+ (1:1, 4:1, 1:3). Analysis of total biomass and relative growth rate revealed a significant 3-way interaction between N level, NO3&#8211; : NH4+ ratio, and species. We found that the C3 grasses showed a greater relative response to increasing N addition than did C4 grasses or forbs. We also found a strong correlation between specific root uptake capacity for N and growth response to N level, for five of the six species. Specific leaf area of green leaves and % N of senesced leaves both showed a significant N-level by ratio interaction. Cautiously interpreted, these species-specific responses in growth and tissue quality could lead to changes in community-level and ecosystem dynamics as atmospheric N deposition continues to rise. We suggest that future studies addressing the potential impacts of N loading on natural communities use inorganic N compositions that are consistent with those expected from atmospheric deposition. 
ER  -

