The Effects of Light and Moisture on Two Species from Contiguous Communities of South-Facing Bluffs in Interior Alaska, U.S.A.

Wesser, Sara

doi:10.2307/1551442

Cited by 2 publications

(1 citation statement)

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“…Other researchers have emphasized the importance of competition in defining the range of subarctic steppe in the boreal forest zone, suggesting that steppe species are restricted by shade-intolerance to areas that trees are unable to colonize. According to this hypothesis, the expansion of woody taxa throughout the Holocene has caused the ranges of steppe taxa to contract to habitats too dry or disturbed for successful tree establishment (Yurtsev 1982;Murray et al 1983;Edwards & Armbruster 1989;Wesser 1991;Wesser & Armbruster 1991). Because steppe in Alaska typically occupies very small treeless patches within which microclimate varies only slightly, assessing the relative importance of competition and microclimate in controlling the distribution of steppe taxa has been difficult.…”

Section: Introductionmentioning

confidence: 99%

Ecology of a steppe‐tundra gradient in interior Alaska

Lloyd

Armbruster

Edwards

1994

J Vegetation Science

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Abstract. Subarctic steppe is currently restricted in interior Alaska and the Yukon Territory to steep, south‐facing river bluffs. Paleoecological and biogeographic evidence suggests that some steppe taxa may have been more widespread during the Full‐Glacial. We examined factors controlling the distribution of steppe taxa on an elevation gradient across a steppetundra ecotone; such analyses may help define potential Full‐Glacial distributions of these taxa. Multivariate analyses suggest that species can be divided into four spatially distinct groups, but individualistic species distributions create considerable overlap among these groups. The steppe‐tundra ecotone comprises a broad zone of mixing between steppe taxa and drought‐tolerant alpine tundra taxa, followed by an abrupt shift to alpine shrub tundra. The transition from low steppe to tundra vegetation is primarily associated with a gradient of decreasing soil temperature. The more abrupt transition from mixed steppe‐tundra to alpine shrub tundra vegetation is primarily associated with changes in soil depth and soil moisture. Variation in vegetation within steppe is associated with gradients in soil phosphorus and moisture. Greenhouse experiments on drought tolerance of two steppe and two tundra taxa suggest that the individualistic distribution of species along the ecotone is partly a function of physiological differences among species. Our analyses of vegetation‐environment relationships support the hypothesis that some components of the steppe community could have been more widespread during the colder Full‐Glacial.

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