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Thursday, January 21, 2016

A New Plant List for Tejon Ranch! By Dr. Mike White, Conservation Science Director



I am happy to announce that we are converting to a new plant list!  Why should you care you ask? The lists that we keep for Tejon Ranch are records of all of the taxa that occur here. [Note: Taxon (plural - taxa) means species, subspecies or varieties of plants and animals. Technically we refer to the two subspecies of a single species (e.g., Eschscholzia lemmonii subsp. kernensis and Eschscholzia lemmonii subsp. lemmonii) as two taxa.] It is one way of documenting the biodiversity of the Ranch, which the Conservancy is charged with protecting, enhancing, and restoring. It also allows us to more fully understand the ecology of Tejon, so to better plan and execute our conservation management activities.
Tejon poppy (Eschscholzia lemmonii subsp. kernensis)

The plant list that we have been using at the Conservancy originally was based on species lists that were generated by consultant surveys of Tejon Ranch Company’s future development areas, and then augmented over the years by the Conservancy’s partners and citizen scientists.  However, plant taxonomy is often based on subtle distinctions in physical characteristics that can be difficult to discern, and is ever-changing based on new research. Without a physical specimen (voucher specimen) for reference, plant identifications can be uncertain and open to disagreements. Having physical specimens of a plant allows plant taxonomists to revisit specimens and the taxonomic names that were assigned them, confirm their identifications if there are questions, and revise their taxonomy in the future as appropriate. If available, a voucher-based species list is a more accurate and powerful tool than one based on unconfirmed identifications, and vouchering specimens is a standard practice of research botanists around the world.
Syntrichopappus lemmonii

The Conservancy is fortunate to have Nick Jensen of the Rancho Santa Ana Botanic Garden working on the Flora of Tejon Ranch for his graduate research (http://tejonflora.org) and access to his extensive voucher-based plant list.
Nick Jensen with Brickellia nevinii
Given Nick’s significant research efforts at Tejon, the Conservancy has decided to abandon our old plant species list in favor of a new voucher-based list derived from Nick’s work to date. The list is a work in progress for Nick as well as the Conservancy, and we will provide updates as appropriate.

A few of the highlights from the new list:

  • There are 968 plant taxa on the list. For context, there are 8,500 plant taxa in California, so Tejon Ranch supports over 10% of the state’s plants in less than 1% of its area.
  • Of the 968 taxa, about 88% are native to California (that’s good!).
  • Those 968 plants occur within 103 different plant families, representing nearly 60% of the plant families present in California.
  • The Sunflower family (Asteraceae) had the highest number of plant taxa at 149.  The next highest was the Grass family (Poaceae) with 73 taxa.
  • There are 12 oak taxa (genus Quercus) at Tejon, representing about 1/3 of the oaks in the state.
  • Some plant genera are particularly rich at Tejon Ranch.  These include the genera Eriogonum (buckwheat) with 27 taxa; Gilia with 18 taxa; Lupinus (lupine) with 15 taxa; and Clarkia (farewell-to-spring), Cryptantha, Mimulus (monkey flower), and Phacelia each with 13 taxa.
  • Nick has documented 42 California Native Plant Society (CNPS)-designated rare plants, a 50% increase in the rare plants known to occur on the Ranch prior to his work!
  • Perhaps most interesting, Nick has found at least three plants that may represent new species to science!



A Lomatium from the Blue Ridge that Nick believes is new to science.


Enjoy!

Monday, January 11, 2016

Riparian habitat management at Tejon Ranch by Dr. Mike White, Conservation Science Director



The word “riparian” is derived from the Latin work ripa, which refers to the banks of a river. Riparian vegetation is adapted to life on river banks, including periodic inundation, movement of sediment and debris, and changes in the shape and location of the river channel. The shape and size of the river valley, channel shape, gradient, and hydrological setting (e.g., total precipitation, amount of precipitation as snow) all determine the plant species and structure of the vegetation communities along the river. Tejon Ranch has a huge diversity of riparian communities, corresponding to the landscape’s topographic, climatic, and hydrological diversity. These different vegetation communities support different wildlife species that use streams and riparian vegetation for cover, food, breeding, and as “movement corridors” through the watershed. These water sources and the variety of vegetative structure provided by riparian communities—herbaceous ground cover, shrubs, and tree canopy—are especially important in an arid landscape such as the southern San Joaquin Valley. Because of these factors, riparian habitats—in association with their adjoining terrestrial vegetation communities—often support high plant and animal species biodiversity.
Lush yerba mansa (Anemopsis california) meadow within the Tejon Creek riparian corridor.

The riparian corridor of El Paso Creek connects low elevation grassland habitats to high elevation mixed conifer habitats.
Riparian and other wetland communities are priorities for conservation management in the Conservancy’s Ranch-wide Management Plan (RWMP). The loss of understory by excessive dry-season grazing, and rooting of the channel and floodplain by feral pigs are the primary threats to the condition of riparian habitats at Tejon Ranch, particularly low elevation reaches of streams on the San Joaquin Valley side of the Ranch such as Tejon Creek, El Paso Creek, and Tunis Creek. Over the last 2 years the Conservancy has been working with our partners at the Tejon Ranch Company and the Echeverria Cattle Company (one of the Tejon cattle lessees) to develop new ranching infrastructure that, when completed in 2016, will allow us to reduce cattle grazing in riparian habitats during warmer, dryer times of the year. We are also exploring the effects of feral pigs by installing experimental pig exclosures in a few riparian areas (more on this below).
 
New fence along lower Tejon Creek (left of photo along toe of slope) to allow better management of the riparian vegetation.
This year Felix Ratcliff, a PhD Candidate at UC Berkeley, completed his 3rd year of research studying riparian habitats on the San Joaquin Valley side of Tejon Ranch, including reaches of Tejon Creek, Chanac Creek, El Paso Creek, and Tunis Creek. Supported by a generous anonymous donation to the Conservancy, Felix is investigating both the environmental factors—geology, soils, and elevation—and management factors—cattle grazing and feral pig disturbance—that shape these riparian communities. Thus, his research will help the Conservancy better understand how to improve the condition of riparian habitats to benefit native wildlife, such as breeding birds, and plants found along creeks on the Ranch.  

Felix Ratcliff checking out wildlife camera results in the field.
Felix has found that distinct plant communities occur on stream reaches with distinct environmental characteristics. Depending on the site, riparian habitats may be dominated by dense willows, have open canopies with annual grasses in the understory, or have massive tangles of wild grapes covering the ground and climbing the trees. The plant species and structure of the habitat determine which wildlife species use the creek. Cattle and pigs are by far the most commonly seen mammals in Felix’s study reaches, but mule deer, bobcats, black bears, mountain lions, and badgers are detected regularly in these riparian areas as well. He has found 5 snake species (California king snake, Pacific rattlesnake, night snake, and gopher snake) and 4 lizards (side blotched lizard, Gilbert’s skink, Western fence lizard, alligator lizard). The Conservancy has also been sponsoring riparian bird surveys conducted by the Southern Sierra Research Station, and Felix is incorporating their data into his analyses. His preliminary analysis shows that some bird species are more likely to occur in areas of the creek with a wider corridor of trees and shrubs.

Cottonwood-willow riparian forest in Tunis Creek, with large trees in the overstory.

Willow riparian scrub in Sacatara Canyon is dominated by shrubby willows with few large overstory trees.
Over the 3 years of the study, the riparian plant communities in his study reaches have remained fairly similar over time. This year the Conservancy installed fencing in 5 reaches of Felix’s study area to evaluate the effects of eliminating disturbance by pigs and cattle. With the installation of new fences and livestock water systems, we now can modify management practices to improve riparian conditions. Using Felix’s baseline data before installing the fencing, we have an opportunity to observe the effects that cattle and pigs have on vegetation (without and with the exclosures). And with the increasing chance of an El Niño winter, we may have the opportunity to see how riparian vegetation responds to a wet winter in different areas (keep your fingers crossed!).

On a side note, the pig exclosures provide a great example of the trials and tribulations of a field biologist (particularly one whose graduate school clock is ticking!). The Conservancy installed the 5 exclosures as part of Felix’s research project to determine the effects of eliminating pigs and cattle from the riparian habitats he is studying.  The exclosures are square-ish, nearly 200 feet on a side, and straddle the creek, which means two sides of each exclosure cross the creek. You may also recall that while we are in our 4th year of drought (come on, El Niño), we did get some pretty good thunderstorms over the summer. Long story short, one of those summer thunderstorms sat over Tejon Ranch and caused very significant flooding and debris flows in El Paso and Tunis Creeks, blowing out the fence segments that crossed the creeks. Obviously not a very effective means of keeping cattle and pigs out! The idea of the experiment was to have 5 different study reaches (out of 15) with exclosures and the rest without. Having 2 of the 5 exclosures compromised was not good experimental design to say the least. Fortunately, with a little elbow grease from Conservancy staff Laura Pavliscak and Scot Pipkin, Felix was able to repair the exclosures. We are now waiting to see what El Niño will bring us but are hoping that we will not have the catastrophic debris flows that destroyed the exclosures this summer.

A forlorn Felix examining the breached fence in the El Paso Creek pig exclosure.
As part of our stewardship mission, the Conservancy will continue to restore and enhance riparian and wetland habitats at Tejon Ranch. Yes, the primary objective of our stewardship is to increase conservation values of these habitats, but we also want to learn from our efforts so that we can understand the best ways to increase conservation values and improve our work in the future. We want to continue sharing these projects with you to illustrate the complex ecology of these habitats and how we can better protect and manage them. So come on out to the Ranch and learn more about our riparian conservation efforts!