Identifying Plant Communities Resistant to Conifer Establishment Along Utility Rights-Of-Way In Washington And Oregon, U.S.

Jeff Shatford; David Hibbs; Logan Norris

doi:10.48044/jauf.2003.021

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Figure 1.
Schematic of the Pacific Northwest region; Xs indicate location of rights-of-way included in our survey.

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Table 1.

Percentage of woody and herbaceous plant cover within six community types identified along electrical transmission rights-of-way in western Washington and Oregon. Values indicate the range of cover estimates recorded for each species in a given community type and a given study site.

Community	Vegetation	TCW (%)	CRG (%)	WF (%)
Alder
Red alder	Alnus rubra	10–80	—	—
Broom
Scotch broom	Cystisus scoparius	—	7–40	12–80
Herbs
Grasses	Poaceae	8–35	5–40	5–65
Forbs	Forbs, various	1–6	1–10	1–10
Bracken fern	Pteridium aquilinum	2–10	2–10	1–5
Thimbleberry	Rubus parviflorus	5–20	—	—
Herb/shrub
Grasses	Poaceae	1–10	2–7	5–15
Forbs	Forbs, various	3–12	3–10	3–10
Bracken fern	Pteridium aquilinum	3–20	2–10	40–80
Trailing blackberry	Rubus ursinus	15–40	2–8	15–25
Sword fern	Polystichum munitum	2–10	15–35	40–55
Snowberry	Symphoricarpus albus	—	—	7–15
Salal	Gaultheria shallon	8–15	5–15	35–65
Oregon grape	Berberis nervosa	1–8	—	—
Salmonberry	Rubus spectabilis	1–11	—	—
Shrub
Snowberry	Symphoricarpus albus	—	15–60	7–85
Thimbleberry	Rubus parviflorus	15–30	12–50	15–35
Salal	Gaultheria shallon	15–95	15–45	35–65
Oregon grape	Berberis nervosa	10–40	—	—
Salmonberry	Rubus spectablilis	10–50	—	—
Tree and tall shrub
Hazel	Corylus cornuta	—	11–70	20–100
Vine maple	Acer circinatum	15–80	25–96	50–75
Cascara	Rhamnus purshiana	—	15–45	20–60
Bigleaf maple	Acer macrophyllum	—	15–35	—

TCW = Tacoma City Watershed; CRG = Columbia River Gorge; WF = Willamette foothills.

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Table 2.

The percentage of area within each community type and the percentage of sample plots without Douglas-fir seedlings for each community type for three study sites in Washington and Oregon, 2000. Community types appear in order of most resistant to least resistant to Douglas-fir seedling establishment. A separate likelihood ratio chi-square test analysis is reported for each site.

Study area (%)	Community type	Plots without Douglas-fir (%)
TCW
9	Herb	100^*
9	Tree/tall shrub	98^*
43	Shrub	89^*
24	Herb/shrub	74
15	Alder	69
		(Chi-square = 44.3; DF = 4; N = 463; P < 0.0001)
CRG
5	Herb	95^*
55	Tree/tall shrub	90^*
4	Broom	84
9	Herb/shrub	79
26	Shrub	77
		(Chi-square = 13.8; DF = 4; N = 461; P < 0.01)
WF
12	Tree/tall shrub	82^*
18	Shrub	77^*
24	Broom	61
2	Herb	60
42	Herb/shrub	49
		(Chi-square + 32.8; DF = 4; N = 452; P < 0.0001)

↵* Observed number of plots without Douglas-fir more than expected by random chance.

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Table 3.
Mean density (s.e.) of Douglas-fir seedlings along three rights-of-way surveyed in the Pacific Northwest, 2000.
Site Density (seedlings/ha) Regrowth after cutting (%)^*
TCW 735 (7.2) 2 (0.8)
CRG 526 (8.0) 15 (1.1)
WF 1586 (10.8) 34 (0.9)
↵* Proportion of seedlings or saplings that had regrown from an uncut lateral branch after having been cut down.