• Aber, J., McDowell, W., Nadelhoffer, K., Magill, A., Berntson, G., Kamakea, M., McNulty, S., Currie, W., Rustad, L. & Fernandez, I. (1998) Nitrogen saturation in temperate forest ecosystems. BioScience, 48, 921934.
  • Binkley, D., Senock, R. & Cromack, K. (2003) Phosphorus limitation on nitrogen fixation by Falcataria seedlings. Forest Ecology and Management, 186, 171176.
  • Borken, W. & Matzner, E. (2004) Nitrate leaching in forest soils: an analysis of long-term monitoring sites in Germany. Journal of Plant Nutrition and Soil Science, 167, 277283.
  • Chapin III, F.S. & Kedrowski, R.A. (1983) Seasonal changes in nitrogen and phosphorus fractions and autumn retranslocation in evergreen and deciduous taiga trees. Ecology, 64, 376391.
  • Chapin III, F.S., Matson, P.A. & Mooney, H.A. (2002) Terrestrial nutrient cycling. Principles of Terrestrial Ecosystem Ecology (eds F.S.ChapinIII, P.A.Matson & H.A.Mooney), pp. 197223. Springer-Verlag, New York.
  • Craine, J.M., Elmore, A.J., Marcos, P.M., Aidar, M.B., Dawson, T.E., Hobbie, E.A. et al. (2009) Research review. Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability. New Phytologist, 183, 980992.
  • Drake, D.C., Peterson, B.J., Galván, K.A., Deegan, L.A., Fleeger, J.W., Friedrichs, C.T., Hopkinson, C.S., Johnson, J.M., Koop-Jakobsen, K., Lemay, L.E. & Picard, C. (2009) Salt marsh ecosystem responses to nutrient enrichment: a paired 15N tracer study. Ecology, 90, 25352546.
  • Fenn, M.E., Poth, M.A., Aber, J.D., Baron, J.S., Bormann, B.T., Johnson, D.W., Lemly, A.D., McNulty, S.G., Ryan, D.F. & Stottlemyer, R. (1998) Nitrogen excess in North American ecosystems: predisposing factors, ecosystem responses, and management strategies. Ecological Applications, 8, 706733.
  • Galloway, J.N., Dentener, F.J., Capone, D.G., Boyer, E.W., Howarth, R.W., Seitzinger, S.P. et al. (2004) Nitrogen cycles: past, present, and future. Biogeochemistry, 70, 153226.
  • Gillingham, A.G. & Thorrold, B.S. (2000) A review of New Zealand research measuring phosphorus in runoff from pasture. Journal of Environmental Quality, 29, 8896.
  • Hartwig, U.A. (1998) The regulation of symbiotic N2 fixation: a conceptual model of N feedback from the ecosystem to the gene expression level. Perspectives in Plant Ecology, Evolution and Systematics, 1, 92120.
  • Larned, S.T., Hicks, D.M., Schmidt, J., Davey, A.J.H., Dey, K., Scarsbrook, M., Arscott, D.B. & Woods, R.A. (2008) The Selwyn River of New Zealand: a benchmark system for alluvial river plain rivers. River Research and Applications, 24, 121.
  • McKerchar, A.I. & Schmidt, J. (2007) Decreases in low flows of the lower Selwyn River? New Zealand Journal of Hydrology, 48, 6372.
  • Menge, D.N.L. & Hedin, L.O. (2009) Nitrogen fixation in different biogeochemical niches along a 120 000-year chronosequence in New Zealand. Ecology, 90, 21902201.
  • Menge, D.N.L., Levin, S.A. & Hedin, L.O. (2009) Facultative versus obligate nitrogen fixation strategies and their ecosystem consequences. American Naturalist, 17, 465477.
  • Nilsen, E.T. & Sharif, M.R. (1983) Carbon isotopic composition of legumes with photosynthetic stems from mediterranean and desert habitats. American Journal of Botany, 84, 17071713.
  • Parfitt, R.L., Schipper, L.A., Baisden, W.T. & Elliot, A.H. (2006) Nitrogen inputs and outputs for New Zealand in 2001 at national and regional scales. Biogeochemistry, 80, 7188.
  • Pate, J.S. & Layzell, D.B. (1990) Energetics and biological costs of nitrogen. The Biochemistry of Plants, a Comprehensive Treatise: Intermediary Nitrogen Metabolism Assimilation, Vol 16 (eds P.K.Stumpf, E.E.Conn, B.J.Miflin & P.J.Lea), pp. 142. Academic Press, San Diego.
  • Pojar, J. & MacKinnon, A. (eds) (1994) Plants of the Pacific Northwest Coast. Lone Pine, Vancouver.
  • Rhoades, C., Binkley, D., Oskarsson, H. & Stottlemyer, R. (2008) Soil nitrogen accretion along a floodplain terrace chronosequence in northwest Alaska: influence of the nitrogen-fixing shrub Shepherdia canadensis. Ecoscience, 15, 223230.
  • Vitousek, P.M., Mooney, H.A., Lubchenco, J. & Melillo, J.M. (1997) Human domination of Earth’s ecosystems. Science, 277, 494499.
  • Watt, M.S., Clinton, P.W., Whitehead, D., Richardson, B., Mason, E.G. & Leckie, A.C. (2003) Above-ground biomass accumulation and nitrogen fixation of broom (Cystisus scoparius) growing with juvenile Pinus radiata on a dryland site. Forest Ecology and Management, 184, 93104.
  • Williams, P.A. & Wiser, S. (2004) Determinants of regional and local patterns in the floras of braided riverbeds in New Zealand. Journal of Biogeography, 31, 13551372.