Burger 



Chapter 16 



Inland Habitat Associations in British Columbia 



1 50 m. It characterizes relatively dry forest in the rain shadow 

 of the Vancouver Island and Olympic Mountains. Very little 

 old-growth remains in this heavily populated zone. Douglas- 

 fir is the dominant tree, with other conifers and broad-leaved 

 trees sometimes common. There has been no research on 

 Marbled Murrelets in this zone, but nesting is likely, because 

 the birds are often seen nearby on the ocean. 



The Mountain Hemlock Zone occurs at 900-1800 m in 

 southern British Columbia (lower on windward slopes) and 

 400-1000 m in the north. It is most common above the 

 Coastal Western Hemlock Zone on the mainland Coast 

 Mountains and the insular mountains of Vancouver Island 

 and the Queen Charlotte Islands. Dominant trees are mountain 

 hemlock (Tsuga mertensiana), amabilis fir, and yellow cedar. 

 Much of this forest occurs as a mosaic among areas of 

 subalpine heath, meadow, and ferns. Nesting has been recorded 

 in these forests on the southern mainland (see below). 



The Alpine Tundra Zone occurs on high coastal 

 mountains, above 1650 m in the south and 1000 m in the 

 north, and is dominated by shrubs (willows and birch), herbs, 

 bryophytes, and lichens. Marbled Murrelets have been reported 

 flying over such habitats (Rodway and others 1993a), but 

 there is no evidence that they nest there in British Columbia. 



Landscape Attributes 



Old-Growth Compared with Second-Growth 



Two studies compared detection frequencies in old- 

 growth and second-growth. Rodway and others (1993a) 

 recorded high densities of activity in intensive surveys in 

 old-growth on the Queen Charlotte Islands (details below), 

 but had only one detection in five intensive surveys in second- 

 growth stands (60-120 years old). In road surveys, detections 

 were reported at 76 percent (n = 25) of old-growth stations, 

 but only at 27 percent (n = 101) of second-growth stations 

 (20- 1 20 years old). In 85 percent of the cases where detections 

 were recorded in second-growth forest, there were stands of 

 old-growth within 500 m. Detection frequencies were 

 significantly higher in old-growth than second-growth, and 

 within second-growth they were significantly higher if there 

 was old-growth nearby (fig. 2). 



Savard and Lemon (in press) reported significantly fewer 

 detections from stations in watersheds with less than 50 

 percent remaining old-growth, compared to more intact 

 watersheds (fig. 3). At fixed stations in May and July, fewer 

 detections were recorded when the proportion of old-growth 

 fell below 75 percent of the watershed. In addition, stations 



D >500 n 151-500 ^ 51-150 0-50 



4 -r 



3 - 



2 



1 



n = 12 



Distance from station (m) 



n = 13 



n = 57 



n = 44 



Spruce-Hemlock Cedar-Hemlock <500 m from old- >500 m from old- 

 growth growth 

 Old-growth Second-growth 



Figure 2 Mean number of Marbled Murrelet detections per road transect station in relation to adjacent 

 habitat type in the Queen Charlotte Islands (from Rodway and others 1 993a) . The sample size (n) is the 

 number of surveys. 



USDA Forest Service Gen. Tech. Rep. PSW-152. 1995. 



153 



