Research

The UC Santa Cruz Campus Natural Reserve holds a unique distinction among many nature reserves in being located on the campus of a thriving university with over 15,000 students. This location makes it an ideal place for students and faculty to conduct both pilot and publishable research. Most of these projects involved UCSC faculty, graduate students, and undergraduates. Below is an excerpt from the UCSC Campus Natural Reserve Annual Report for 2014-15 that lists recent research highlights.

Ongoing Research Projects

UCSC Forest Ecological Research Plot (UCSC FERP) expansion census:

In 2012 the FERP was inducted into the Smithsonian Institute’s Center for Tropical Forest Science-Forest Global Earth Observatories (CTFS-ForestGEO) international network of now 62 forest plots. The FERP is one of 14 such plots in North America, and represents the only plot in a Mediterranean climate. The Principal Investigator on this project is Dr. Gregory S. Gilbert of the Environmental Studies department. During the original census, 8,180 stems from 31 woody plant species in 18 families were measured and tagged. During FY 2011-12, each of these stems was re-measured, individuals with multiple stems were tagged, and plants that had reached the “new recruit” size-class of at least 10 mm in diameter at 1.3 meters from the ground were measured, tagged, and mapped. FY 2012-13 marked the beginning of the plot’s expansion from 6 to 15 hectares—from a 200 m x 300 m rectangle to a 400 m2 square. This expansion was continued and finally completed during FY 2014-15, bringing areas of redwood forest and significant topography to the plot. By cataloguing the distribution and abundance of woody species on the plot, researchers are able to analyze the dynamics of species interaction, recruitment, and population structure upon the landscape. As mentioned on the CTFS-ForestGEO website (http://www.ctfs.si.edu/site/Santa+Cruz), the expansion “bring[s] several new aspects to the site, such as the ability to follow population dynamics, an expansion into different soil types, and the inclusion of an area that has undergone significant canopy mortality in the last two decades for unknown reasons.” A total of 32 interns worked on the expansion census project in FY 2014-15, led each Quarter by two paid undergraduate intern supervisors. These students continued woody plant census work in the expansion zone and the challenging field work of tracking down and addressing problems discovered in the data set. An additional 22 interns worked on the FERP’s Phenology Litter Traps, Canopy Photography, and Herps on the FERP internships. The FERP continues to provide world-class research experiences on the UCSC campus, a mere half hour walk from our traditional indoor classrooms. See Figure 5a, 5c, and 5h for a photos of undergraduate interns at work on the FERP (note the white coveralls for poison oak protection!).

The FERP also hosts a variety of associated research projects that aim to increase the overall understanding of the plot’s forest dynamics. Several are listed below:

• Meteorological stations: A total of 13 meteorological stations were placed on the FERP by Dr. Michael Loik (ENVS) and his ENVS 196L students in 2009. Data are collected hourly at 1m above ground level using Decagon sensors, and are available on Dr. Gilbert’s FERP website https://ferp.ucsc.edu. Solar radiation, air temperature and relative humidity, precipitation, soil temperature and volumetric soil moisture, and leaf wetness are measured by a variety of sensors. These sensors continued to collect data through FY 2014-15.

• Phenology: A series of 44 litter traps distributed within the FERP are checked every two weeks. Fallen leaves, twigs, flowers, bark, and other vegetative matter are catalogued to create an evolving timeline of seasonal change. This information canthen be used by researchers studying the effects of climate change or those wondering when the best time may be to collect data on a particular species. Student interns and employees are involved in both field and laboratory work associated with the phenology study. This work was also on-going throughout FY 2014-15, and the PVC/rebar frames required to support 72 additional traps on the FERP’s expansion zone were established as well. Mesh screen will be added to these frames during fall 2015, enabling the collection of phenology data from the entire 16 ha plot.

• Soil research: In late May/early June 2015, soil scientist Ben Turner of Smithsonian Tropical Research Institute came from Panama for a week long, high-intensity soil survey of the 16 ha FERP plot. A large team of undergraduate interns and volunteers, graduate students, faculty and staff joined Ben for a wide range of activities including field work (digging five 1 m wide x 2 m long x 1.8 m deep soil pits, taking over 160 soil core samples from all over the plot) and lab work (including KCl extractions of soil samples, soil moisture measurement). Analysis of this work is on-going. See Appendix 5 for locations of the FERP soil pits, which were later outfitted with sturdy wooden covers to secure them for future educational use with Dr. Weixin Cheng’s soils classes and Dr. Greg Gilbert’s various courses and research internships.

• Terrestrial small mammal trapping: The Small Mammal Undergraduate Research in the Forest (SMURF) project is a collaboration between the UCSC Natural Reserves, the Ken Norris Center, and ENVS professor Dr. Chris Wilmers’ lab. A sequence of three trapping nights is conducted once per academic quarter and is coordinated by ENVS graduate students and ENVS and/or EEB undergraduate interns and volunteers. Two small mammal species were predominately encountered during 2014-15 field sessions: Peromyscus californicusand Peromyscusboylii. This research allows undergraduates to gain useful field ecology skills and contributes to a long-term data set associating rodent distribution and abundance to the detailed forest structure and composition data available through the FERP. Rosa Johnson, an ENVS major and SMURF intern, finished her senior thesis The Impact of Perceived Risk on Rodent ForagingHabits (Johnson 2014) in fall 2014; her abstract is copied below.Many animals make trade-offs between foraging efficiency and predation risk, sacrificing feeding opportunities in favor of predator avoidance. This study investigates the impact of man-made trails on foraging habits of nocturnal Peromyscus mice species in UC Santa Cruz’s Forest Ecology Research Plot. I hypothesize that due to high use of human trails by terrestrial predators (coyotes and bobcats), mice perceive more risk on trails than off, making them less likely to forage for food near trails. I also ask whether mice will be less likely to forage for food in areas of higher exposure, with less understory. I measured how these factors affected foraging by mice by placing trays of seeds at varying distances from trails and understory cover. I found no evidence that rodents sacrifice foraging opportunities near trails, but mice were less likely to forage in exposed areas with low understory cover. This implies that trails have minimal impact on small mammal foraging habits.

• Tree physiology: EEB Senior Alex Chacon, a seasoned FERP intern turned FERP field crew supervisor and full-time summer technician, completed a project investigating the water-use strategies of two common mixed-evergreen forest trees. He examined the water potential, stomatal conductance, vulnerability curves, and hydraulic anatomy of Pacific madrone (Arbutus menziesii) and coast live oak (Quercus agrifolia). Despite the ongoing drought, both tree species in his study area seemed to be fairly hydrated but used different strategies (“water saving” for the oak vs. “water spending” for the deeper-rooted madrone) to accomplish this. See Appendix 6 for Chacon’s research poster.

• FERP bat research: The FERP bat monitoring project uses a passive acoustic bat detector to monitor bat activity in the canopy and understory of the forest. ENVS graduate student Elissa Olimipi, EEB researcher Winifred Frick, and undergraduate interns use specialized software called Sonobat to help parse noise from real bat calls, and to then identify bat calls to species. Each quarter, the researchers monitor for two weeks and add to a long term data set that will help them understand bat activity throughout the year. The most commonly recorded species is the California myotis (Myotis californicus), a small insectivorous bat that can be found along the west coast of North America from Alaska to Mexico.

• Ehrharta erecta research: Plant Sciences graduate student Courtenay Ray continued her on-campus study of the invasive Ehrharta erecta (panic veldt grass). She has established several plots within the campus core and its ravines where she is investigating the effects of different control treatments for the species. Through this project she has mentored several undergraduate students, allowing them the opportunity to develop their own thesis research under her guidance. In FY 2014-15, EEB undergraduate Annika Rose-Person began research that will result in her completed thesis next year. She examined the legacy effects of E. erectra—does this organism hinder the growth of native plant species into the future through the alteration of soil chemistry? Annika’s research poster is presented in Appendix 7.

• California red-legged frog habitat usage: ENVS senior Anna Ringelman wanted to study Califonia red-legged frogs (Rana draytonii) on campus, and demonstrated great initiative by seeking out several collaborators that enabled her work. She worked closely with EEB professor Dr. Barry Sinvero and Brett Hall of the UCSC Arboretum to design and implement a study that is now being written up for publication and that will be sent to the US Fish and Wildlife Service to gain permission to implement the habitat alteration at the UCSC Arboretum that the study recommends. The abstract from her thesis, The Influence of Thermal and Hydric Conditions on the Habitat Usage of a Threatened Amphibian Species (Ringelman 2015), follows below. This study evaluated the hydric and thermal response of agar models that mimic frog ecophysiology to riparian overstory and to treatments representing the available habitat conditions (dry/wet substrate and sun/shade exposure to sunlight) at the UCSC Arboretum pond. This site provides the only suitable breeding habitat available for the lower campus population of the threatened California red-legged frog (Rana draytonii; CRLF), and has experienced rapid increases in riparian canopy cover within the pond basin. The abundance and distribution of adult CRLF across eight experimental sites were then evaluated in relation to the correlation between agar model response, climate conditions and canopy cover to identify any associations between these variables and differential habitat selection by CRLF. I hypothesized that (1) models deployed on dry substrates would exhibit higher rates of water loss than those deployed on wet substrates, and that placement in full sunlight would further exacerbate water loss rates. I further hypothesized that (2) the density of canopy cover would be significant across all treatment categories, and that sites with higher levels of canopy openness would exhibit higher levels of CRLF abundance. I deployed agar models and data-loggers at eight sites within the pond basin, and calculated the relative rates of water loss experienced under the treatment conditions. Additional climate data (air temperature, relative humidity) and canopy overstory density were collected and analyzed, and both night and day surveys were conducted for CRLF. I found that canopy overstory density had a significant influence on the water loss and Te experienced by models, and that these factors were in turn significantly associated with the abundance of CRLF at experimental sites. As such, riparian overstory is a habitat characteristic that land managers should take into account when maintaining breeding site habitat for CRLF.

• Molecular Ecology—California voles: EEB Professor Beth Shapiro’s pilot molecular research with her graduate seminar (BIOE 295) in spring 2014 was built upon by undergraduates in her brand-new Molecular Ecology course (BIOE 137/L) in winter 2015. The research involved collecting tissue samples from California voles (Microtus californicus) at several local sites: Natural Bridges State Park, Younger Lagoon Reserve, east of Coolidge Dr. bordering Pogonip City Park, North Marshall Field, and Fort Ord Natural Reserve. Dr. Shapiro and her students extracted and amplified DNA from the tissue samples, and attempted to distinguish variation between these presumably geographically isolated vole populations. A portion of the project used microsatellite marker data to determine population structure among the sampled voles (disregarding the Younger Lagoon and Natural Bridges samples). The interpretation of the results, as stated by the graduate student T.A., follows: “There are two distinct vole populations that were sampled: Fort Ord voles and the North Marshall Field and Coolidge Dr. voles. Microsatellites evolve much more quickly than the cyt b gene, so the disagreement between the two may be because there is only recent divergence in the two populations and the cyt b gene evolves too slowly to detect this at present.”

• Ben Lomond Grassland Bird Monitoring Project: The CNR received a small amount of grant funding through the UCSC Sustainability Office’s Working Group funds to conduct a grassland bird monitoring study. These funds paid for an undergraduate EEB student, Alex Rinkert, an expert birder at his young age, to conduct the project’s extensive avian and vegetation survey field work. Alex analyzed the data and wrote up his results as his senior thesis. The goals of the study include the following: To understand the current status and distribution of landbirds breeding in grassland habitat at the southern end of Ben Lomond Mountain encompassing UCSC, Pogonip, Wilder Ranch and Gray Whale Ranch State Park, and Moore Creek Preserve; to characterize the management regimes in each grassland parcel and how grassland birds respond to these landscape alternations; to establish baseline demographic data on grassland bird species that will provide perspective on past and future observations and studies on southern Ben Lomond Mountain and elsewhere in the Santa Cruz Mountains; and to offer grassland management suggestions for UCSC, City of Santa Cruz, Land Trust of Santa Cruz County, and California State Park natural resource managers. The study found that grassland birds in the study area preferred recently grazed or burned landscapes.