Recently, the Rare Plant Conservation Program (RPCP) performed annual fall demographic monitoring for several species, including Lakela’s Mint, Savannas Mint, Clasping warea, and Carter’s mustard. This monitoring takes place during the peak of flowering season for each species, which allows for the collection of important reproductive output data from the populations. This monitoring is synergistic with our habitat improvement projects for scrub and sandhill habitats: we can correlate the presence and number of plants with the type of habitat improvement work that was performed. We can also observe changes in the type and abundance of pollinators with improved habitat quality.
Improving habitat opens up sand and canopy gaps, and reduces dense stands of oaks and pines, and eliminated invasive species. This same higher quality habitat that helps better support rare plants also helps better support other species, including native pollinators.
Although we often observe the non-native honeybee, Apis mellifera, on the flowering plants during monitoring, improved habitat conditions bring a greater abundance of the native bees. The presence of native pollinators is important to help maintain levels of genetic diversity in a population and to maximize production of viable seeds. For instance, in populations of Lakela’s Mint, fewer plants in the population are pollinated by honeybees, because they are mainly attracted by large plants in full sun. Therefore, fewer plants contribute genetic material for the next generation of seedlings. Also, honeybees strongly tend to visit the numerous flowers on one plant (rather than skimming from plant to plant as native bees tend to do), which promotes selfing instead of cross-pollinating.
Previous studies by the RPCP have shown that selfing produces roughly one-third of the amount of viable seeds compared with cross-pollinating. With our previous research showing the positive impact that native bees have on sustaining healthy populations of Lakela’s Mint, this is a sight we are always thrilled to see.
Blog posting by Cheryl Peterson, Rare Plant Conservation Manager at Bok Tower Gardens