Standard vegetation surveys under-represent ecologically and culturally important forbs in an endangered temperate grassland

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Bryan A. Endress and Joshua P. Averett, Eastern Oregon Agricultural Research Center, Oregon State University, La Grande, OR, Shawn Steinmetz and Eric Quaempts, Department of Natural Resources, Confederated Tribes of the Umatilla Indian Reservation, Pendleton, OR

Background/Question/Methods
Forbs are a culturally and ecologically important, yet poorly studied, component of the endangered Pacific Northwest Bunchgrass (PNB) ecosystem of western North America. Because many PNB forbs emerge early in the spring and senesce at the onset of summer, traditional vegetation surveys, which occur in mid-summer, likely under-represent forb richness, diversity, and abundance. We evaluated how the timing of sampling affected estimates of perennial forb abundance (cover), richness, and floral density, by sampling 29 plots three times: mid-summer (July), as well as seven (May) and 12 (April) weeks prior.
Results/Conclusions
Timing had a large effect on estimates, with significant declines in forb richness (42%), cover (80%), and floral density (95%) between April and July. The density of Camas quamash and Lomatium cous, two culturally important forbs, declined 91% and 92% respectively, from April to July. Nearly 65% of forbs were of significance to indigenous people of the region. The consequences of biased estimates are significant, as under-sampling: 1) limits our basic understanding of fundamental ecological processes and interactions; 2) hinders effective conservation and management because we lack information regarding forb abundance, status and trends, and 3) the effects disproportionately impact indigenous communities as many forbs are culturally important resources for subsistence and ceremonial purposes.