After long-term decline, are aspen recovering in northern Yellowstone?

摘要: Abstract In northern Yellowstone National Park, quaking aspen ( Populus tremuloides ) stands were dying out in the late 20th century following decades of intensive browsing by Rocky Mountain elk Cervus elaphus ). 1995–1996 gray wolves Canis lupus reintroduced, joining bears Ursus spp.) and cougars Puma concolor to complete guild large carnivores that prey on elk. This was followed a marked decline density change distribution during years 1997–2012, due part increased predation. We hypothesized these changes would result less an increase height young aspen. 2012, we sampled 87 randomly selected Yellowstone, compared our data baseline measurements from 1997 1998. Browsing rates (the percentage leaders browsed annually) 1997–1998 consistently high, averaging 88%, only 1% sample plots taller than 100 cm; none 200 cm. much lower at 44%, average with 34% >100 cm 5% >200 cm. Most (62%) variation 2012 explained intensity. Furthermore, 25% had least five saplings tall enough escape (⩾200 cm spring height), condition has not occurred for happened despite recent drought. Sapling recruitment did until decreased, substantial distribution, significantly related stand productivity or climate fluctuations. These results suggest carnivore restoration, through effects prey, may aid recovery where have been suppressed