. The Canadian field-naturalist. Natural history. 18 The Canadian Field-Naturalist Vol. 115 SPECIES RICHNESS DIVERSITY EVENNESS 1 5-i 1 -, _ r-a nil 4m nil < < < OS o o u u 0- 10 m < < < < OS OS o o u u 0- 10m < < < OS O O 0- 10m -1 5 -, 1 -, ml inii ?mi « OS o O -20 m lllllllll < < < < <£ OS O O U U < < < < K OS O O u u -20 m. < < < < C6 K O O -20 m llll -30 m -30 m < < OS O u -30 m 1111 kill iilll < < < < a dj o o u u -40 m < < < < as
. The Canadian field-naturalist. Natural history. 18 The Canadian Field-Naturalist Vol. 115 SPECIES RICHNESS DIVERSITY EVENNESS 1 5-i 1 -, _ r-a nil 4m nil < < < OS o o u u 0- 10 m < < < < OS OS o o u u 0- 10m < < < OS O O 0- 10m -1 5 -, 1 -, ml inii ?mi « OS o O -20 m lllllllll < < < < <£ OS O O U U < < < < K OS O O u u -20 m. < < < < C6 K O O -20 m llll -30 m -30 m < < OS O u -30 m 1111 kill iilll < < < < a dj o o u u -40 m < < < < as u. o O u u -40 m < < < K OS O U - 40 m DISTANCE FROM THE IMPOUNDMENT EDGE Figure 6. Species richness, diversity, and evenness index values I and SE ? for the woody plants at 10 m intervals within 40 m of the impounded edge of recently abandoned (RAb, 12 years since abandonment) impoundments and the downstream comparison plots in the Swanson River basin of the Chapleau Crown Game Preserve, 1993. of reduced canopy and more sunlight, riparian trees tend to lean towards the water or have more foliage in that direction (Johnson 1983). Since Beavers can- not directionally fall trees (Novak 1976), we propose that Beavers over evolutionary time may have select- ed to cut trees close to the water as they are more apt to fall towards or into the water because of this dis- proportionate growth on their stream side. The third reason involves the risk of predation. The trade-off between foraging activity and preda- tor risk has long been regarded as one of the great ecological conflicts experienced by animals (Milinski and Heller 1978; Abrams 1984; Werner and Gillian 1984; McNamara and Houston 1987; Lima and Dill 1990; Anholt and Werner 1995; Werner and Anholt 1996; Eklov and Halvarsson 2000). The importance of predation during evolu- tionary time is clear, but growing evidence suggests that animals also have the ability to assess and behaviourally influence their risk
Size: 1845px × 1354px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectnaturalhistory, booky
