Controls on production of bryophytes in an arctic tundra stream

摘要: SUMMARY 1. Two bryophyte taxa (Hygrohypnum spp. and, to a lesser extent, Fontinalis neomexicana) were abundant in riffles within phosphorus-fertilized reaches of the Kuparuk River (North Slope, Alaska), but much less common fertilized pools and virtually absent unfertilized river. We conducted field experiments using stems clumps both species artificial bryophytes test hypotheses that growth was strongly limited by low phosphorus concentrations reaches, epiphytes pools. 2. Stem tips Hygrohypnum did not elongate when grown pool riffle environments. In elongated significantly, although there no significant difference elongation stem placed [2.5 ± 0.9 cm (SD)] as opposed (2.8 cm) for 32 days. 3. F. neomexicana significantly all sites. There control (2.1 1.1 4.7 0.1 cm, respectively) 0.8 2.7 respectively). 4. Biomass increments these same followed similar patterns except pools. lost weight environments grow pools, accumulated 181 44 335 200% initial biomass 1992 (over days) 1993 days), respectively. 38 39 98 47% riffles, Total greater than riffles. 5. Artificial mosses (untwisted, natural fibre rope) used assess effects flow regime on derrital epiphyte accumulation zone. Epiphyte detrital mass 4–4.5 times average slow-flowing fast-flowing chlorophyll 4 riffles. This probably brought about increased deposition reduced grazing invertebrates It is likely could throughout river, are secondarily detritus interference competition with epiphytic algae