CORRELATION OF NEIGHBORHOOD RELATIONSHIPS, CARBON ASSIMILATION, AND WATER STATUS OF SAGEBRUSH SEEDLINGS ESTABLISHING AFTER FIRE
Western North American Naturalist
Interactions of Artemisia tridentata ssp. vaseyana (mountain big sagebrush) and neighboring herbs may affect community development following fire in sagebrush steppe. Biomass, photosynthesis, and water relations were measured for seedlings of A. t. vaseyana occurring at different distances from neighboring herbs in the initial growing seasons following fire, when herbs dominate plant community cover. Biomass gain was nearly twice as great for A. t. vaseyana seedlings located furthest from
... furthest from neighboring herbs, compared to seedlings located adjacent to neighboring herbs. Similarly, carbon assimilation (Anet) was greater for A. t. vaseyana in microsites further from herbs, but only in early and not mid-late summer. Xylem pressure potentials (XPP) of seedlings were not correlated with their distances to neighboring herbs, on any sampling date. Moreover, supplemental watering had no effect on relationships between biomass of A. t. vaseyana seedlings and distances to neighboring herbs. In mid-late summer, when Anet, stomatal conductance, and XPP of seedlings decreased markedly as soils dried, Anet was no longer correlated with distances to neighboring herbs. Longer-term responses of A. t. vaseyana to neighboring herbs following fire may result largely from interactions between them in early summer, before the seasonal onset of water limitations. Although soil-plant water relations could explain much of the seasonal variability in Anet and growth of seedlings, correlations of Anet or biomass and proximity to neighboring herbs were not likely to result from water limitations in microsites near herbs.