Spatiotemporal variation in pollinator taxa on the santa ana river wooly star Eriastrum densifolium ssp. Sanctorum (Milliken) mason (Polemoniaceae)

Authors

  • C. Eugene. Jones California State University, Fullerton, CA
  • Fern L. Hoffman California State University, Fullerton, CA
  • Patricia Nunes-Silva University of Guelph, Ontario, Canada
  • Robert L. Allen California State University, Fullerton, CA
  • Axhel Munoz California State University, Fullerton, CA
  • Marion Erickson California State University, Fullerton, CA
  • Douglas Stone California State University, Fullerton, CA
  • Youssef Atallah California State University, Fullerton, CA

DOI:

https://doi.org/10.26786/1920-7603(2020)531

Abstract

Flood control, via the construction of the Seven Oaks Dam in the Santa Ana River in southern California, has altered habitat in the downstream alluvial wash community and jeopardized the persistence of pioneer plant species that rely on periodic flood-scouring and sand recharge. One species, Eriastrum densifolium ssp. sanctorum (“Eriastrum”), an endangered perennial, has been greatly affected and persists in spatially separated populations on successional vegetation terraces. We made “dawn to dusk” observations of pollinators in three phenological stages at four sites, representing young and old seral stages, to identify primary pollinators and to elicit daily, site, and seasonal patterns of visitors. Data were compared to previous observations and correlated with annual rainfall to determine long-term trends. Shifts in pollinator taxa have occurred, with some consistency through time and space, during nine years. The sites with the highest pollinator abundance (older sites) are least suited to Eriastrum. Hummingbirds (prevalent in early season) and the Acton giant flower-loving fly (prevalent in late season) have been consistently present across years, whereas other taxa have varied. A shift from native bees to non-native bees has occurred, although native bees in the families Halictidae and Apidae (Micranthophora and Melissodes) remain important. In general, there was no correlation between taxa abundance and rainfall. Eriastrum appears to be a generalist able to take advantage of the behaviour, cycling, and availability of diverse pollinators daily, seasonally, and annually.

 

Author Biographies

C. Eugene. Jones, California State University, Fullerton, CA

Professor of Botany Emeritus, 

Fern L. Hoffman, California State University, Fullerton, CA

She was one of the graduate students who studied this plant as their thesis topic for her Master Degree in Biology under my direction. 

Patricia Nunes-Silva, University of Guelph, Ontario, Canada

She was extensively involved in the final editing and rewrite of this paper. 

Robert L. Allen, California State University, Fullerton, CA

He was one of the graduate students who studied this plant as their thesis topic for his Master Degree in Biology under my direction. 

Axhel Munoz, California State University, Fullerton, CA

He was one of the graduate students who studied this plant as their thesis topic for his Master Degree in Biology under my direction. 

Marion Erickson, California State University, Fullerton, CA

She was one of the graduate students who studied this plant as their thesis topic for her Master Degree in Biology under my direction. 

Douglas Stone, California State University, Fullerton, CA

He was one of the graduate students who studied this plant as their thesis topic for his Master Degree in Biology under my direction. 

Youssef Atallah, California State University, Fullerton, CA

He was one of the graduate students who studied this plant as their thesis topic for his Master Degree in Biology under my direction.  He was also extensively involved on a number of aspects of this project as a Postdoc under my direction. 

Published

2020-04-16

How to Cite

Jones, C. E., Hoffman, F. L., Nunes-Silva, P., Allen, R. L., Munoz, A., Erickson, M., Stone, D., & Atallah, Y. (2020). Spatiotemporal variation in pollinator taxa on the santa ana river wooly star Eriastrum densifolium ssp. Sanctorum (Milliken) mason (Polemoniaceae). Journal of Pollination Ecology, 26. https://doi.org/10.26786/1920-7603(2020)531

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Articles