Hopland Research and Extension Center

Knobcone pine forests are challenging to manage because high intensity crown fires are thought to be necessary for successful regeneration.  The effects of the season of prescribed fire and fire surrogates is not understood in knobcone pine forests.  Using a complete randomize design with replication this experiment explores the efficacy of different management strategies on knobcone pine regeneration.  Experimental treatments are: prescribed fire including spring and fall burns, mechanical and fire treatments including felling and lop and scatter followed by prescribed fire in spring and fall and mechanical only in spring and fall.  This project, funded primarily by the Joint Fire Sciences Program, is in its initial stages with most treatment units located at the Bureau of Land Management Cow Mountain Recreation Area.  One unit initially chosen as a control treatment, at HREC will facilitate agency cooperation and extension of results.  Pre-treatment vegetation, fuels, and bird survey data will be collected in all units in the spring through fall.  Post-treatment tree, shrub, fuel, and bird abundance variables will be measured for at least three years.

Chaparral fire management has become increasingly challenging as California's population expands into the wildland fringes.  Fuel management techniques such as out-of-season prescribed fire and mastication (mechanical shredding) are often used to reduce wildfire risk in chaparral, yet the ecological consequences of these treatments have not been carefully studied.  To address this issue, Dr. Scott Stephens and Jennifer Potts of UC Berkeley are investigating the effects of fall, winter and spring prescribed fire and mastication in Northern California Coast Range chaparral.   Pre and post-treatment monitoring of plant and bird recovery has been ongoing since 2001 and will continue through 2005.  With over 100 acres of replicated experimental treatments, this research project is one of the only fire management studies of its kind.  Preliminary results already suggest that plant and bird responses vary significantly after prescribed fire and mastication treatments conducted in different seasons of the year, particularly in relation to non-native grass cover and bird abundance.  Final data analysis is expected to be complete by 2006.  This project has enormous potential to change future chaparral fire management practices.  The research effort will synthesize five years of plant and bird recovery data at a level of detail that has never before been studied.  This information will help fire managers to make informed ecological decisions in the face of social, political, and economic demands related to wildfire protection.

The objective of this study is to evaluate the effect of co-pollinators in the coevolving interaction between Greya politella and their hosts: L. cymbalaria, L. parviflorum and L. heterophyllum.  Greya politella is close relative of yucca moths, and its several host plants has been used to evaluate the components of the geographic mosaic theory of coevolution. The geographic range of the moths extends from Montana to southwestern Colorado and from southern British Columbia to southern California.  G. politella is restricted to Lithophragma throughout its range, although it uses different species in different parts of its geographic range.

This is a long term study of the effects of grazing and fire management on water quality, hydrology, and plant community dynamics of oak woodland watersheds. This project is a companion project to our watershed work at UC SFREC, and project 82-99 at HREC. Since 1998 we have monitored stream flow, water quality, and plant community composition on 4 oak woodland watersheds (A, B, C, and D) at HREC. Watersheds A and B are grazed lightly by sheep (RDM >1000 lb/ac) while watersheds C and D have been excluded from domestic livestock since 1955. Starting this past year, following 5 years of pre-treatment data collection, we introduced prescribed fire as a treatment. Watersheds B and C were burned in June 2003. We are currently collecting post fire data on water quality, streamflow, and plant community and will continue for another year post treatment. We are currently working on data analysis for a manuscript comparing water quality between watersheds A and B (grazed lightly to moderately by sheep; RDM > 1000 lb/ac) and C and D (non-grazed since ~1955) over 5 water years. We are also preparing a manuscript reporting the hydrologic characteristics of these intermittent oak woodland watersheds.

HREC has been monitoring precipitation as part of the National Atmospheric Deposition Program since 1979.  The goal of this network of sites is to provide a data base for the development of research to address the problem of acidic deposition and its effects on agriculture, forests, rangelands, and fresh water streams and lakes.  The monitoring sites are rural with limited point sources of emissions within the immediate vicinities of the collectors.  The monitoring program is long-term and it is on-going.

Plant species can differ in their effects on almost every aspect of ecosystem structure and function. For the past 9 years, we have been studying how eight of the dominant plant species at Hopland differ in their impacts on multiple aspects of ecosystem structure and function, including: soil aggregation, soil carbon and nutrient capital, nutrient recycling, soil moisture, the soil microbial community, and the activity of voles and gophers. Our research has shown that plant species effects on these different ecosystem properties and processes changes seasonally, and changes with time since plants are established at a site. Furthermore, when plant species are replaced by other plants, their impacts on soil properties and processes persist for at least 5 years. These ""legacy effects'"" do not mirror the ecosystem effects of the plants when they were present at the site. All of these patterns of plant species effects could be predicted using multiple plant traits, including litter chemistry, root:shoot biomass, plant labile C inputs, and plant species effects on soil temperature and moisture. Shifts in the relative importance of these traits was primarily responsible for changes in plant species effects on nutrient cycling with season, with time since establishment, and with time after the species have been replaced by other species. In addition, in collaboration with Chuck Vaughn, we found that nutrient recycling is not only mediated by decomposition of litter senesced at the end of the growing season, but that self-thinning of seedlings can contribute at least as much to seasonal N turnover and plant available N.

Riparian management is one of the most controversial issues facing landowners in California today.  Though a great deal of information exists for coniferous situations in California relatively few, long-term monitoring studies exist for oak woodland riparian systems.  The project is intended to demonstrate 1) the importance of riparian zones to non-fish vertebrates, and 2) the importance of managing specific riparian habitat elements for the benefit of terrestrial obligate species.   Because birds are so readily visible and recognizable by most members of the public, they were selected as the taxa for monitoring to better convince landowners of the benefits of riparian vegetation management.

This is an ongoing long-term project that is attempting to address P sources, sinks and storage in Clear Lake.  The project is attempting to identify the influence of P chemistry, P cycling and environmental factors on the growth and distribution of noxious bluegreen algal (cyanobacteria) blooms in Clear Lake.  The aims of the project are to understand the seasonal and interannual variation in the P cycle and characterize the P loading from the watershed (which includes more than 300 acres on HREC), especially as it relates to interannual variability in rainfall and nutrient input to Clear Lake. 

One effect of the 1960s Watershed II vegetation conversion is that stream flow is still perennial; but summer flows comprise a small fraction of annual discharge.  Also, flow ceases approximately 100 yards downstream of our gauge.  In future analysis, we will compare annual discharge listed in 1960s reports to annual discharge today to evaluate whether flow per rainfall is different today relative to historical conditions, and describe biological implications.

Four oak woodland research and demonstration watersheds were developed at the UC Hopland Research and Extension Center.  Staff constructed and installed 3-foot H-flumes in each of the watersheds as the primary hydrologic measuring device.  Automated stream flow monitoring and water quality sampling equipment was installed and calibrated at all flume sites.  An automated weather station, located on site, will monitor rainfall, air temperature, soil temperature, relative humidity, wind speed, wind direction and solar radiation.  A 2-3 year collection of baseline hydrologic, water quality, vegetation and soils data will be collected before a portion of the watersheds are subjected to land use treatments.  Potential treatments include grazing management ("heavy" v. "moderate" v. no grazing) and/or prescribed burning.  Development of manuscripts and monitoring guides on the characterization of seasonal and within storm flow and concentration patterns, evaluation of turbidity as an estimator of total suspended solid concentration, and development of water and nutrient budgets for oak woodland watersheds is planned using the data set.  These watershed sites also serve as demonstration sites for extension of results as well as monitoring methods to landowners, managers, UCCE academics, regulators, and the interested public.

Time scales are critical to understanding hydrological phenomena and their influence on biotic processes.  Streamflow, for example, can be expressed over several time scales: annual, seasonal, daily, and sub-daily scales all have different meanings for human and ecosystem management applications.  Over the past two years, we have measured streamflow from HREC Watershed II at 15-minute intervals to explore discharge differences across different temporal scales.  Watershed II was part of an elaborate study from 1953 through 1973 to evaluate effects of vegetation changes on streamflow; though we cannot make comparisons of historical flow relative to flow today because the historical data were discarded, data from Watershed II can still provide important insights about regional hydrologic processes.  Our data illustrate hydrologic patterns similar to other Mediterranean-climate catchments: annual discharge is high relative to other regions in the US.  Streamflow is also seasonal: most runoff occurs during the rainy season.  Flows also may vary through the day: mean daily flow is insufficient to characterize peak event flow during winter, and does not adequately express the daily fluctuations caused by evapotranspiration during spring and summer.

The PCN (Pecked Curvilinear Nucleated) rock art tradition is believed to represent one of the earliest rock art 'styles' in California and is identified as a pecked oval or circle that produces a raised or nucleated center, nearly always occurring on a greenstone boulder with a high talc content.  The geographical distribution of the nearly 100 known PCN sites spans several hundred miles of the Coastal Ranges.  Three of these sites are located within the boundaries of Hopland Field Station. This project will contextualize this early rock art tradition, by exploring the relationship of the boulders to regional settlement patterns, associated archaeological materials, and how the phenomenon may "interact" with nearby landscape features.  This is dissertation study that will include a thorough archive research of pertinent literature, including all regional site reports on file at the Northwest Information Center at Rohnert Park; California, a review of previous archaeological work performed at Hopland Field Station; a systematic pedestrian surface survey and shovel testing, where indicated and with permission; 3-D Laser scanning of the PCN boulders; and, if warrented and permitted, excavation of test pits adjoining the identified boulders.  The sub-surface portion of the study will strive to identify artifactual material that may be linked with the PCN tradition or provide insight into understanding the prehistoric cultural practices and peoples responsible for leaving the images on the rocks, and to seek landscape features that might have played a role in selection of the site locations by prehistoric peoples.

Establish and maintain an unmanned observatory at the Hopland Research and Extension Center, specifically in the southern bluff of the Watershed I experimental area. It is intended that this installation will be operated for 30 years or longer. Periodic (usually annual) reports of research progress resulting from work conducted at Hopland will be provided to the Center.