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here. - Ministry of Forests, Lands and Natural Resource Operations

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A Douglas-fir Drought-Decline Complex<br />

During the aerial surveys, tree mortality <strong>of</strong> an unknown cause was detected along the west<br />

side <strong>of</strong> Sugar Lake. Four individual polygons covering 289 hectares were mapped. Followup<br />

ground assessments found a combination <strong>of</strong> Douglas-fir beetle <strong>and</strong> Armillaria root disease,<br />

although drought was likely the catalyst, as not all trees had a biotic causal agent associated with<br />

mortality. The soils in this area are very<br />

coarse, <strong>and</strong> t<strong>here</strong>fore very sensitive to<br />

any water deficits. The st<strong>and</strong>s examined<br />

were mature even-aged Douglasfir<br />

with a minor component <strong>of</strong> western<br />

larch, western red cedar <strong>and</strong> western<br />

hemlock. Douglas-fir <strong>and</strong> western<br />

larch were the most prone to mortality.<br />

Most species, with the exception<br />

<strong>of</strong> western red cedar, have experienced<br />

poor growth over the last several years<br />

as exhibited by the crown symptoms.<br />

It is likely that both Douglas-fir beetle<br />

<strong>and</strong> Armillaria are responding to host<br />

stress; these symptoms may be indicative<br />

<strong>of</strong> changing climatic effects on dry<br />

transitional sites.<br />

A hillside above Sugar Lake showing<br />

symptoms <strong>of</strong> drought/decline, root disease,<br />

<strong>and</strong> Douglas-fir beetle.<br />

Similar but less extensive symptoms have been observed in the Kootenays for the last few<br />

years, most obviously near Trout Lake, w<strong>here</strong> Douglas-fir on dry to mesic sites within the<br />

Interior Cedar-Hemlock zone have displayed thin crowns, dying tops, <strong>and</strong> scattered mortality.<br />

These symptoms have not been detectable from the air but have been observed during other<br />

ground survey work.<br />

Several other minor damaging agents were detected during the aerial surveys. These included<br />

20 hectares <strong>of</strong> cottonwood leaf rust, 24 hectares <strong>of</strong> armillaria root disease, 17 hectares <strong>of</strong><br />

bear damage, 125 hectares <strong>of</strong> birch decline (near Falkl<strong>and</strong>), 82 hectares <strong>of</strong> aspen decline<br />

(near Crater Mountain), 500 hectares <strong>of</strong> wildfire, 70 hectares <strong>of</strong> windthrow, 24 hectares <strong>of</strong><br />

flooding, <strong>and</strong> two l<strong>and</strong>slides that damaged 10 hectares <strong>of</strong> mature timber.<br />

<strong>Ministry</strong> <strong>of</strong> <strong>Forests</strong>, <strong>L<strong>and</strong>s</strong> <strong>and</strong> <strong>Natural</strong> <strong>Resource</strong> <strong>Operations</strong>, Kamloops, B.C.<br />

27<br />

Flooding damage in the Larch<br />

Hills area <strong>of</strong> the Okanagan TSA.

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