19. Nutrient Manipulations in Terrestrial Ecosystems
natures than do soil N and S, and thus their fate can
often be traced within the system (Koopsman et al.
1997).
Summary and Conclusions
Nutrient addition experiments can be used to address a variety of questions, including the role of
nutrients in mediating ecosystem processes, nutrient effects on plant and microbial community dynamics, the limitations on plant growth and ecosystem production, and the response of ecosystems
to increased atmospheric deposition of nutrients.
When designing a nutrient addition experiment,
it is critical to minimize the impact of the fertilizer additions on soil pH, salt toxicity, and the
supply of other potentially limiting nutrients that
are not being tested (e.g., S, Ca). It is also important to understand whether a lack of response
to fertilization is due to the absence of limitation
for that nutrient, or the failure of the nutrient additions to become available to plants. This is especially important when comparing responses of
plant growth to nutrient additions across sites,
where factors controlling fertilizer availability
could differ substantially.
Isotopes are an invaluable tool for attaining a
mechanistic understanding of the fate and dynamics
of nutrient additions. They can be used to test how
much of the fertilizer becomes available to plants,
elucidate mechanisms of nutrient retention and loss,
detect changes in soil nutrient dynamics, and trace
competitive uptake between different plant species
and microbial groups. The incorporation of isotope
methods into nutrient addition experiments should
solidify our understanding of the controls of nutrients over all aspects of the ecosystem.
Acknowledgments This chapter is based on ideas
developed under funding from the Bonanza Creek
Long-Term Ecological Research Program (National Science Foundation BSR-9196130 and U.S.
Forest Service PNW 96-5024-2-CA), a grant from
the California Sustainable Agriculture Research
and Education Program, a NASA Earth System
Science Fellowship (ESS/97-0127), a National Science Foundation doctoral dissertation improvement
grant (DEB-9801487), and funding from the Divi303
sion of Agriculture and Natural Resources to the
University of California Hopland Research and Extension Center.
References
Aber, J.D.; Magill, A.; Boone, R.; Melillo, H.M.;
Steudler, P.; Bowden, R. Plant and soil responses to
chronic nitrogen additions at the Harvard Forest, Massachusetts. Ecol. Applic. 3:156-166; 1993.
Aerts, R; Wallen, B.; Malmer, N. Growth-limiting nutrients in Sphagnum-dominated bogs subject to low
and high atmospheric nitrogen supply. J. Ecol.
80:131-140; 1992.
Aerts, R; Berendse, F. The effect of increased nutrient
availability on vegetation dynamics in wet healthlands. Vegetatio 76:63-69; 1988.
Arnolds, E. Former and present distribution of stipitate
hydnaceous fungi (Basidiomycetes) in the Netherlands. Nova Hedwigia 48:lO7-142; 1989.
Beaton, J.e.; Fox, RL.; Jones, M.B. Production, marketing, and use of sulfur products. In: Engelstad, O.P.,
ed. Fertilizer Technology and Use. 3rd ed. Madison,
WI: Soil Science Society of America; 1985:416-454.
Berendse, F.; Elberse, W.T.H.; Geerts, R.H.M.E. Competition and nitrogen loss from plants in grassland ecosystems. Ecology 73:46-53; 1992.
Bilbrough, C.J.; Caldwell, M.M. Exploitation of springtime ephemeral N pulses by six Great Basin plant species. Ecology 78:231-243; 1997.
Bobbink, R. Effects of nutrient enrichment in Dutch
chalk grassland. J. Appl. Ecol. 28:28-41; 1991.
Bolland, M.D.A.; Weatherly, A.J.; Gilkes, R.J. The longterm residual value of rock phosphate and superphosphate fertilizers for various plant species under field
conditions. Fertil. Res. 20:89-100; 1989.
Boswell, F.C. Production marketing and use of nitrogen
fertilizers. In: Engelstad, O.P., ed. Fertilizer Technology and Use. 3rd ed. Madison, WI: Soil Science Society of America; 1985:229-292.
Bouchard, D.e.; Williams, M.K.; Surampalli, RY. Nitrate contamination of groundwater: Sources and potential health effects. Am. Water Works Assoc. J.
84:85-90; 1992.
Bowman, W.D.; Theodose, T.A.; Schardt, J.C.; Conant,
R.T. Constraints of nutrient availability on primary
production in two alpine tundra communities. Ecology
74:2085-2097; 1993.
Bramley, RG.V.; Barrow, N.J. The reaction between
phosphate and dry soil. II. The effect of time, temperature and moisture status during incubation on the
amount of plant available P. J. Soil Sci. 43:759-766;
1992.
natures than do soil N and S, and thus their fate can
often be traced within the system (Koopsman et al.
1997).
Summary and Conclusions
Nutrient addition experiments can be used to address a variety of questions, including the role of
nutrients in mediating ecosystem processes, nutrient effects on plant and microbial community dynamics, the limitations on plant growth and ecosystem production, and the response of ecosystems
to increased atmospheric deposition of nutrients.
When designing a nutrient addition experiment,
it is critical to minimize the impact of the fertilizer additions on soil pH, salt toxicity, and the
supply of other potentially limiting nutrients that
are not being tested (e.g., S, Ca). It is also important to understand whether a lack of response
to fertilization is due to the absence of limitation
for that nutrient, or the failure of the nutrient additions to become available to plants. This is especially important when comparing responses of
plant growth to nutrient additions across sites,
where factors controlling fertilizer availability
could differ substantially.
Isotopes are an invaluable tool for attaining a
mechanistic understanding of the fate and dynamics
of nutrient additions. They can be used to test how
much of the fertilizer becomes available to plants,
elucidate mechanisms of nutrient retention and loss,
detect changes in soil nutrient dynamics, and trace
competitive uptake between different plant species
and microbial groups. The incorporation of isotope
methods into nutrient addition experiments should
solidify our understanding of the controls of nutrients over all aspects of the ecosystem.
Acknowledgments This chapter is based on ideas
developed under funding from the Bonanza Creek
Long-Term Ecological Research Program (National Science Foundation BSR-9196130 and U.S.
Forest Service PNW 96-5024-2-CA), a grant from
the California Sustainable Agriculture Research
and Education Program, a NASA Earth System
Science Fellowship (ESS/97-0127), a National Science Foundation doctoral dissertation improvement
grant (DEB-9801487), and funding from the Divi303
sion of Agriculture and Natural Resources to the
University of California Hopland Research and Extension Center.
References
Aber, J.D.; Magill, A.; Boone, R.; Melillo, H.M.;
Steudler, P.; Bowden, R. Plant and soil responses to
chronic nitrogen additions at the Harvard Forest, Massachusetts. Ecol. Applic. 3:156-166; 1993.
Aerts, R; Wallen, B.; Malmer, N. Growth-limiting nutrients in Sphagnum-dominated bogs subject to low
and high atmospheric nitrogen supply. J. Ecol.
80:131-140; 1992.
Aerts, R; Berendse, F. The effect of increased nutrient
availability on vegetation dynamics in wet healthlands. Vegetatio 76:63-69; 1988.
Arnolds, E. Former and present distribution of stipitate
hydnaceous fungi (Basidiomycetes) in the Netherlands. Nova Hedwigia 48:lO7-142; 1989.
Beaton, J.e.; Fox, RL.; Jones, M.B. Production, marketing, and use of sulfur products. In: Engelstad, O.P.,
ed. Fertilizer Technology and Use. 3rd ed. Madison,
WI: Soil Science Society of America; 1985:416-454.
Berendse, F.; Elberse, W.T.H.; Geerts, R.H.M.E. Competition and nitrogen loss from plants in grassland ecosystems. Ecology 73:46-53; 1992.
Bilbrough, C.J.; Caldwell, M.M. Exploitation of springtime ephemeral N pulses by six Great Basin plant species. Ecology 78:231-243; 1997.
Bobbink, R. Effects of nutrient enrichment in Dutch
chalk grassland. J. Appl. Ecol. 28:28-41; 1991.
Bolland, M.D.A.; Weatherly, A.J.; Gilkes, R.J. The longterm residual value of rock phosphate and superphosphate fertilizers for various plant species under field
conditions. Fertil. Res. 20:89-100; 1989.
Boswell, F.C. Production marketing and use of nitrogen
fertilizers. In: Engelstad, O.P., ed. Fertilizer Technology and Use. 3rd ed. Madison, WI: Soil Science Society of America; 1985:229-292.
Bouchard, D.e.; Williams, M.K.; Surampalli, RY. Nitrate contamination of groundwater: Sources and potential health effects. Am. Water Works Assoc. J.
84:85-90; 1992.
Bowman, W.D.; Theodose, T.A.; Schardt, J.C.; Conant,
R.T. Constraints of nutrient availability on primary
production in two alpine tundra communities. Ecology
74:2085-2097; 1993.
Bramley, RG.V.; Barrow, N.J. The reaction between
phosphate and dry soil. II. The effect of time, temperature and moisture status during incubation on the
amount of plant available P. J. Soil Sci. 43:759-766;
1992.