ARS | Publication request: Differential Phytosociological Interactions Involving Male and Female Atriplex bonnevillensis

Submitted to: Western North American Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2009
Publication Date: July 15, 2009
Citation: Sinclair, J., Emlen, J.M., Rinella, M.J., Snelgrove, J., Freeman, D.C. 2009. Differential Phytosociological Interactions Involving Male and Female Atriplex bonnevillensis. Western North American Naturalist. 69:475-480.

Interpretive Summary: Male and female wind-pollinated plants are often separated spatially. Therefore, the two sexes are apt to encounter different plant species and may interact differently with the same co-occurring species. Here, we examine interactions that influence male and female reproductive potential in a perennial shrub. Using a technique which assesses species interactions based on cover classes, we show that a species of one invasive weed competes significantly with females but not males, while another weed competes with males but not females. The effect of competition only became apparent when we corrected for fertility based on location. These results imply that competition from different species must be considered when studying plants that display spatial segregation of the sexes.

Technical Abstract: Males and females of wind-pollinated dioecious plants often exhibit spatial segregation of the sexes. This partial niche separation has most often been explored using abiotic niche axes. If the sexes are truly separated in space then they are apt to encounter different species and, to the extent that the niches of the sexes do differ, the sexes may respond differently to the same co-occurring species and may also be heavily affected by different species. Here, we examine interspecific interactions that influence male and female reproductive potential in A. bonnevillensis. Using Emlen’s Interaction assessment, a technique which assesses species interactions based on cover classes, we show that species of Salsola compete significantly with females but not males, while Halogeton glomeratus competes with males but not females. The effect of competition only became apparent when we corrected for site-specific fertility. These results imply that differential competition must be considered when studying dioecious plants that display spatial segregation of the sexes.