An Endangered Wildflower and Local Food Production – Is There a Link?
CBI biologist Jessie Vinje and partners just completed a 3-year experimental study on the Rancho Jamul Ecological Reserve (RJER) in San Diego County, CA. The study assessed various nonnative grass and forb control techniques, including prescribed fire, to restore a historically occupied Otay tarplant population and associated native grasslands and forblands (wildflower fields) that were once more common in San Diego County. Vinje recently presented her findings at the 2015 24th Annual Cal-IPC Symposium and also led a field trip with her partners to RJER to explain the various restoration techniques and to showcase the success of the project.
I’ve often heard and read about the importance of saving endangered animal and plant species. Considering my line of work, it’s obvious to me why all species on this planet are important and worth saving; however, I also know that it’s been far easier for conservationists to explain the importance of saving endangered animals like the giant panda, mountain gorilla, and black rhino over endangered plants. Those endangered mammals are charismatic, symbolic and for the most part, much easier for people to relate to than endangered plants.
The Conservation Biology Institute (CBI), The Nature Conservancy, the California Department of Fish and Wildlife, and other partners recently completed a project to enhance degraded wildflower and native grassland habitat on the Rancho Jamul Ecological Reserve located in San Diego County, California. The overall project goal was to restore an Otay tarplant population that had not been seen for approximately ten years on Rancho Jamul.
Otay tarplant is an endangered, annual wildflower that grows only in southern California and northern Baja California, Mexico. It is a declining species in San Diego County but was presumably much more abundant several hundred years ago prior to the arrival of the Spanish and American settlers. Currently there are only 36 Otay tarplant occurrences known to occur in the United States.
Otay tarplant grows in clay soils along with many native wildflowers and although there is some debate about this, at least one source claims that prior to Spanish arrival, large portions of southern coastal and inland California were covered with vast native wildflower fields in the springtime. Developments and habitats invaded by
nonnative grasses and forbs have replaced many of these vast wildflower fields and because of habitat loss and degradation, many wildflower fields and plant species known to inhabit the wildflower fields, such as Otay tarplant, are now uncommon in San Diego County.
Based on previous photographs and correspondence, the area supporting the Otay tarplant population on Rancho Jamul was also previously covered with native wildflowers. According to at least one historical source, wildflower-covered hillsides used to occur on Rancho Jamul and were rented for beehives during the late-1800’s.
CBI and partners restored the Otay tarplant population to thousands of individuals after three years. Not only was this species restored, but many other native wildflowers were restored too and over the past three years, the area has been awash in springtime wildflower color.
But why does this matter? Why are expanses of wildflowers important to humans? And why are endangered wildflowers, like Otay tarplant important?
The literature linking the benefits of healthy ecosystems and habitats, such as native wildflower fields, to humans are plentiful, but I’ve only chosen one of these benefits – food production – to highlight because it may be arguably the single most important reason to protect natural habitats and ecosystems and the plant and animal species, that call these habitats home.
An accompanying research project on Rancho Jamul will likely show that insect diversity is higher in native wildflower dominated habitats than adjacent degraded nonnative habitats. Copious amounts of literature link the importance of wild and managed pollinators to worldwide food production – in fact, approximately three-quarters of global food crops require pollination.
While many of these crops are pollinated using managed honeybees, other pollinators including feral honeybees and other wild insects are equally as important and more important in some cases. Managed honeybees alone cannot replace the pollination benefits of wild insects that are lost as their habitat is destroyed.
A recent study involving 41 crop systems from around the world determined that fruit set (proportion of a plant’s flowers that are fertilized and produce mature fruits or seeds) increased significantly with visitation by wild insects. This study also found wild insects provided better quality pollination than honeybees alone for most of the crops included in the study. Examples of the crops included in this study include cotton, almonds, strawberries, watermelons, pumpkins, tomatoes, blueberries, and coffee. Don’t most of us like and/or need at least one or two of these crops?
Another study found that fruit set for some crops decreased with distance from natural areas and according to one article (with some caveats), “native pollinators –almost exclusively bees - may be responsible for almost $3.07 billion of fruits and vegetables produced in the United States.”
Furthermore, native pollinators may be able to provide all of the pollination needs for some crops in agriculture settings that contain natural habitats and/or that are situated adjacent to natural habitats. Restoring natural habitats and including florally diverse natural and semi-natural habitats adjacent to, or situated within agriculture settings is one research recommendation for maintaining native pollinator diversity, abundance, health, and persistence.
San Diego County has a long history of agriculture and produces important insect pollinated crops including avocado (wholly insect pollinated) and citrus crops (some types partially insect pollinated). In fact San Diego County is the number one producer of avocados nationally. To continue to provide food items such as avocados, we need to ensure that healthy natural habitats (such as native wildflower fields) exist in proximity to agricultural settings or restore/enhance natural habitats so that sufficient floral resources are available to both native, wild, and managed pollinators. Doing so will likely increase those pollination services necessary for local and global food production, which benefits humans directly and at least in this case, also benefits an endangered plant species – Otay tarplant (coincidentally, the genus for Otay tarplant is listed as a species that supports a diversity of bee species).