. Proceedings of the Symposium on Management of Forest and Range Habitats for Nongame Birds, May 6-9, 1975, Tucson, Arizona. Birds Conservation Congresses; Birds Habitat Congresses; Range management Congresses; Wildlife habitat improvement Congresses. the ground, which of course will support indivi- duals of substantial weight. In coniferous forests, on the other hand, many foraging oppor- tunities are in the outer zones of canopies, where the twigs or needles will support only small individuals or where food resources may be available only to individuals of relatively small dimensions. Specie
. Proceedings of the Symposium on Management of Forest and Range Habitats for Nongame Birds, May 6-9, 1975, Tucson, Arizona. Birds Conservation Congresses; Birds Habitat Congresses; Range management Congresses; Wildlife habitat improvement Congresses. the ground, which of course will support indivi- duals of substantial weight. In coniferous forests, on the other hand, many foraging oppor- tunities are in the outer zones of canopies, where the twigs or needles will support only small individuals or where food resources may be available only to individuals of relatively small dimensions. Species Dominance Given the apparent richness in species numbers and densities in most coniferous forest types, one should expect that generally no single species should markedly dominate the avifauna ( account for most of the indivi- duals present in the stand). I have calculated species dominance rather simply, as the percent of all individuals recorded which belong to the single most abundant species, and to the com- bined populations of the two most abundant species in the census. The census suimnariza- tions of table 2 suggest that on the average 17-27 percent of the individuals present belong to the single most abundant species while 30-46 percent of the individuals are included in the two most abundant species. Dominance tends to be relatively high in immature stages of Northeastern coniferous forests and in Rocky Mountain forests, and relatively low in mature Northeastern forests and Sierra Nevada forests. The difference between Sierra Nevada and Rocky Mountain avifaunas is interesting and reflects the fact that while densities are similar in the two forest regions. Sierra avifaunas on the average contain 7 more species per census plot than Rocky Mountain areas. Dominance of the single most abundant species is related to species number for coniferous forests in all regions in figure 3. As expected, there is a general tendency for dominance to decrease as species numbers i
Size: 1907px × 1310px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorunitedstatesforestservice, bookcentury1900, bookpublis
