Community dynamics in old growth and second growth hemlock forests

Questions What impact, if any, is the hemlock woolly adelgid having on eastern hemlocks in North Carolina? Are other tree species responding with respect to relative density, relative basal area or importance value? How does species richness increase with area in eastern hemlock forests? How does the species area relationship change over time in eastern hemlock forests?

Great Smoky Mountains National Park Joyce Kilmer Memorial Forest Highlands Ranger District Plots 11 Second growth Ave. Elev: 2617 ft 12 Old growth Ave. Elev: 3045 ft Second growth Old growth Field sites of second growth and old growth hemlock communities in western North Carolina

Carolina Vegetation Survey protocol 50 m 20 m 10 total modules for trees 4 intensively sampled modules for herbs

10 cm 30 cm 1 m 3.3 m 10 m Intensively Sampled Module

Questions What impact, if any, is the hemlock woolly adelgid having on eastern hemlocks in North Carolina? Are other tree species responding with respect to relative density, relative basal area or importance value? How does species richness increase with area in eastern hemlock forests? How does the species area relationship change over time in eastern hemlock forests?

Life history of the hemlock woolly adelgid The hemlock woolly adelgid has two hosts: –Tsuga sp. Passive dispersal Asexual reproduction Density dependent shift to a winged sexuperae –Picea sp. Winged sexuperae Sexual reproduction No native spruce are suitable hosts This results in two waves of mortality in hemlock with the smaller hemlocks dying first.

Tsuga can Acer rub Betula len Rhodo max Kalmia lat Average change in abundance of small (0 – 2.5 cm dbh) individuals Old Growth Second Growth ** Average change in abundance

Questions What impact, if any, is the hemlock woolly adelgid having on eastern hemlocks in North Carolina? Are other tree species responding with respect to relative density, relative basal area or importance value? How does species richness increase with area in eastern hemlock forests? How does the species area relationship change over time in eastern hemlock forests?

Relative Value Relative density, relative basal area and importance value in old growth forests Tsuga canadensis Acer rubrum Betula lenta Rhododendron maximum Kalmia latifolia *

Relative density, relative basal area and importance value in second growth forests Relative Value Tsuga canadensis Acer rubrum Betula lenta Rhododendron maximum Kalmia latifolia * *

Summary of successional change in tree layer Small hemlocks are decreasing in absolute abundance in both old growth and second growth forests, with no corresponding increase in larger size classes. In old growth forests, Rhododendron maximum is increasing in relative abundance. In secondary growth forests, Tsuga canadensis is increasing in relative abundance and importance values.

Questions What impact, if any, is the hemlock woolly adelgid having on eastern hemlocks in North Carolina? Are other tree species responding with respect to relative density, relative basal area or importance value? How does species richness increase with area in eastern hemlock forests? How does the species area relationship change over time in eastern hemlock forests?

Carolina Vegetation Survey protocol 50 m 20 m 10 total modules for trees 4 intensively sampled modules for herbs

Species richness at 1000 m 2 StageMeanRange Post-adelgid, old growth Pre-adelgid, old growth Post-adelgid, second growth Pre-adelgid, second growth

Average species richness in old growth hemlock forests at increasing scales (m 2 ) Pre-adelgidPost-adelgid

Average species richness in second growth hemlock forests at increasing scales (m 2 ) Pre-adelgidPost-adelgid

Old GrowthSecond Growth Average change in species richness at increasing scales in old growth and second growth hemlock forests 0 ** Average change in species richness

Questions What impact, if any, is the hemlock woolly adelgid having on eastern hemlocks in North Carolina? Are other tree species responding with respect to relative density, relative basal area or importance value? How does species richness increase with area in eastern hemlock forests? How does the species area relationship change over time in eastern hemlock forests?

Pre-adelgid, old growth Log 10 area Species-area relationships in hemlock forests before the hemlock woolly adelgid Log 10 species richness

Log 10 area Pre-adelgid, second growth Species-area relationships in hemlock forests before the hemlock woolly adelgid Log 10 species richness

Pre-adelgid, old growth Pre-adelgid, second growth Log 10 area Species-area relationships in hemlock forests before the hemlock woolly adelgid Log 10 species richness

Log 10 area Pre-adelgid, old growth Pre-adelgid, second growth Species-area relationships in hemlock forests before the hemlock woolly adelgid Log 10 species richness

Log 10 area Log 10 species richness Post-adelgid, old growth Post-adelgid, second growth Species-area relationships in hemlock forests after the hemlock woolly adelgid

Log 10 species richness Log 10 area Post-adelgid, old growth Post-adelgid, second growth

Post-adelgid, old growth Pre-adelgid, old growth Log 10 species richness Log 10 area Change in the species area relationship over time in old growth forests

Post-adelgid, second growth Pre-adelgid, second growth Log 10 species richness Log 10 area Change in the species area relationship over time in second growth forests

Post-adelgid, old growth Pre-adelgid, old growth Post-adelgid, second growth Pre-adelgid, second growth Log 10 species richness Log 10 area Change in the species area relationship over time

Parameters of species area relationship Log S = Z Log A + Log C StageZ valueSE Post-adelgid, old-growth forest Pre-adelgid, old-growth forest Post-adelgid, second-growth forest Pre-adelgid, second-growth forest

Summary of species richness and species area relationship results Species richness decreased slightly at the largest scales in second growth forests. The primary difference in species area relationships are between second growth and old growth. There is no difference in species area relationships from before and after the hemlock woolly adelgid. –Time may not be long enough. In old growth forests, species do not accumulate with area as quickly as in second growth forests.

Acknowledgments Committee –Robert Wyatt –Bob Peet –Peter White –Tom Wentworth –Allan Strand US Forest Service National Park Service Highlands Biological Station Plant Ecology Lab at UNC Karen Patterson, Claire Newell, Dan Pittillo,Larissa Knebel, Aaron Cooper