title: Nitrogen nutrition of poplar trees.
abstract: Many forest ecosystems have evolved at sites with growth-limiting nitrogen (N) availability, low N input from external sources and high ecosystem internal cycling of N. By contrast, many poplar species are frequent constituents of floodplain forests where they are exposed to a significant ecosystem external supply of N, mainly nitrate, in the moving water table. Therefore, nitrate is much more important for N nutrition of these poplar species than for many other tree species. We summarise current knowledge of nitrate uptake and its regulation by tree internal signals, as well as acquisition of ammonium and organic N from the soil. Unlike herbaceous plants, N nutrition of trees is sustained by seasonal, tree internal cycling. Recent advances in the understanding of seasonal storage and mobilisation in poplar bark and regulation of these processes by temperature and daylength are addressed. To explore consequences of global climate change on N nutrition of poplar trees, responses of N uptake and metabolism to increased atmospheric CO(2) and O(3) concentrations, increased air and soil temperatures, drought and salt stress are highlighted.
authors.affiliation: Albert-Ludwigs-University Freiburg, Institute of Forest Botany and Tree Physiology, Freiburg, Germany. Heinz.rennenberg@ctp.uni-freiburg.de
authors.forename: H
authors.initials: H
authors.lastname: Rennenberg
authors.forename: H
authors.initials: H
authors.lastname: Wildhagen
authors.forename: B
authors.initials: B
authors.lastname: Ehlting
mesh_terms: D026905:Amino Acid Transport Systems / Q000378:metabolism; D027321:Anion Transport Proteins / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D017753:Ecosystem; D000091285:Nitrate Transporters; D009584:Nitrogen / Q000378:metabolism*; D010126:Ozone / Q000378:metabolism; D017440:Photoperiod; D024301:Plant Bark / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D032107:Populus / Q000378:metabolism* / Q000502:physiology; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012621:Seasons; D012965:Sodium Chloride / Q000378:metabolism; D012987:Soil / Q000032:analysis; D013696:Temperature; D014197:Trees / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D026905:Amino Acid Transport Systems; D027321:Anion Transport Proteins; D000091285:Nitrate Transporters; D010937:Plant Growth Regulators; D000644:Quaternary Ammonium Compounds; D012987:Soil; D014867:Water; D002245:Carbon Dioxide; D012965:Sodium Chloride; D010126:Ozone; D009584:Nitrogen