Experimental Evidence for Nitrogen Limitation in a Northern Ozark Stream

摘要: Nutrient enrichment experiments were conducted during low flow periods in 1985 and 1986 a northern Ozark stream characterized by nitrate-N concentrations molar ratios of TN:TP less than 20:1. Enrichment with nitrate to concentration 3-6 times greater ambient, either alone or combination phosphate addition, stimulated periphytic chlorophyll 4-6 × AFDM 2-5 over unenriched controls two 30-d experiments. An intermediate increase response addition was observed when averaged 19:1. Differences periphyton accrual among treatments influenced snail grazing (Goniobasis) biomass N-enriched continued the period, but remained at levels control P-enriched treatments. Low ≤ 20:1 also characteristic 16 sites on 10 streams Plateau 1986, sug...