Role of brown bears (Ursus arctos) in the flow of marine nitrogen into a terrestrial ecosystem.

摘要: We quantified the amount, spatial distribution, and importance of salmon (Oncorhynchus spp.)-derived nitrogen (N) by brown bears (Ursus arctos) on Kenai Peninsula, Alaska. tested confirmed hypothesis that stable isotope signature (δ15N) N in foliage white spruce (Picea glauca) was inversely proportional to distance from salmon-spawning streams (r=–0.99 P<0.05 two separate watersheds). Locations radio-collared bears, relative their a stream, were highly correlated with δ15N depletion across same gradient (r=–0.98 –0.96 Mean rates redistribution salmon-derived adult female 37.2±2.9 kg/year per bear (range 23.1–56.3), which 96% (35.7±2.7 bear) excreted urine, 3% (1.1±0.1 feces, <1% (0.3± 0.1 retained body. On an area basis, salmon-N as high 5.1±0.7 mg/m2 year within 500 m stream but dropped off greatly increasing distance. estimated 15.5–17.8% total derived salmon. Of that, had distributed 83–84%. Thus, can be important vector into riparian ecosystems, effects are variable spatially function density.