Modern pollen rain within and adjacent to two giant sequoia (Sequoiadendrongiganteum) groves, Yosemite and Sequoia national parks, California

Analysis of modern pollen (from polsters) and plant percentage coverage (from relevés) within and near two giant sequoia (Sequoiadendrongiganteum) groves provide data on the relationship between plant abundance and pollen dispersion. Most Sequoiadendron pollen is deposited within or near the groves, substantiating previously established theoretical models on pollen dispersion. Within the groves, Sequoiadendron is only slightly overrepresented by its pollen (R value average, 1.6). At the Tuolumne Grove, Sequoiadendron pollen averages 1.5% at stations within 450 m of the grove boundary. Pollen percentage is slightly higher (8%) for similar stations at Lost Grove. This contrasts with the more widely dispersed pollen of Pinus and Quercus, and the less widely dispersed Chrysolepis and Cornus. Patterns of pollen dispersal away from the groves are consistent with the prevailing wind direction and diurnal air mass movements. For Sequoiadendron, the relatively poor dispersal has implications for future paleoecologic studies interpreting the sedimentary pollen record from meadow sediment cores; and for understanding the exchange of genetic information between these trees that grow in stands somewhat isolated from each other.