title: Heterogeneity of soil surface ammonium concentration and other characteristics, related to plant specific variability in a Mediterranean-type ecosystem.
abstract: Heterogeneity and dynamics of eight soil surface characteristics essential for plants--ammonium and nitrate concentrations, water content, temperature, pH, organic matter, nitrification and ammonification rates--were studied in a Mediterranean-type ecosystem on four occasions over a year. Soil properties varied seasonally and were influenced by plant species. Nitrate and ammonium were present in the soil at similar concentrations throughout the year. The positive correlation between them at the time of greatest plant development indicates that ammonium is a readily available nitrogen source in Mediterranean-type ecosystems. The results presented here suggest that plant cover significantly affects soil surface characteristics.
authors.affiliation: Faculdade de Ciências, Centro de Biologia Ambiental (CBA), Universidade de Lisboa, Campo Grande, Bloco C2, Piso 4, 1749-016 Lisbon, Portugal. ccruz@fc.ul.pt
authors.forename: Cristina
authors.initials: C
authors.lastname: Cruz
authors.forename: Ana M F
authors.initials: AM
authors.lastname: Bio
authors.forename: Aldo
authors.initials: A
authors.lastname: Jullioti
authors.forename: Alice
authors.initials: A
authors.lastname: Tavares
authors.forename: Teresa
authors.initials: T
authors.lastname: Dias
authors.forename: Maria Amélia
authors.initials: MA
authors.lastname: Martins-Loução
mesh_terms: D044822:Biodiversity; D018533:Biomass; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D009566:Nitrates / Q000032:analysis; D063245:Plant Development; D011174:Portugal; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D012621:Seasons; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D013696:Temperature; D014197:Trees; D014867:Water
chemical_list: D006812:Humic Substances; D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D012987:Soil; D012989:Soil Pollutants; D014867:Water