Vernal pool restoration and management issues for Yolo County’s Grasslands Regional Park Report by: Students of UC Davis’ Restoration Ecology Class (ENH 160), Spring 2010, compiled by Sarah Hoskinson and Valerie Eviner Professor: Valerie Eviner, [email protected] TA: Sarah Hoskinson 1 Notes This document is a product from UC Davis’ Restoration Ecology class (ENH 160) in the spring of 2010, and is a result of the hard work of the students. Each topic was written by an individual student, as noted at the start of each report. Some of these reports have been modified in an effort to synthesize and streamline this report. Due to logistical issues (inability to import parts) some figures are missing. Synthesis sections derive from class discussion. Acknowledgements We thank Kent Reeves and Scott Lines from the Yolo County Parks and Resources Department for guidance on key topics that they needed addressed, lecturing to the lab section, giving tours and background information on the site, and allowing us access to the study site. We also thank Carol Whitham for sharing her knowledge of vernal pools with the lab section during field trips to the study site. This project was made possible through the University of California, Davis and the USDA NRI CSREES Managed Ecosystem Program through a grant to Valerie Eviner. 2 Contents Introduction 4 Site overview 5 Vernal pool complex characterization 8 Project synthesis- management/ restoration plan 11 Regional vernal pools overview Distribution of vernal pools in the Central Valley 14 Vernal pool hydrology 35 Vegetation characterization 52 Special status invertebrates Conservancy fairy shrimp (Branchinecta conservation) 83 Vernal pool fairy shrimp (Branchinecta lynchi) 101 Vernal pool snail (Fossaria sonomensis) 112 Other animals Native solitary bees (Andenidae family) 126 Western spadefoot toad (Spea hammondii) 143 Dabbling ducks (Anas spp.) 158 Special status native plants Crampton’s tuctoria (Tuctoria mucronata) 173 Colusa grass (Neostapfia colusana) 188 Alkali milk vetch (Astragalus tener var. tener) 205 Hedge-hyssop (Gratiola spp.) 223 San Joaquin Spearscale (Atriplex joaquiniana) 239 Owl’s clover (Castilleja campestris) 248 Other native plants Salt grass (Distichlis spicata) 265 Goldfields (Lasthenia fremontii) 280 Marbles (Psilocarphus sp.) 297 Coyote thistle (Eryngium sp.) 315 Downingia spp. (D. insigins, bicornuta, ornatissima) 325 Vernal pool dodder (Cuscuta howelliana) 341 Popcorn flower (Plagiobothrys sp.) 350 Invasive plants Perennial pepperweed (Lepidium latifolium) 371 Field bindweed (Convolvulus arvensis) 389 Manna grass (Glyceria declinata) 400 Russian thistle (Salsola tragus) 414 Mediterranean barley (Hordeum marinum) 431 Management tools- Effects of grazing on vernal pools 444 Appendix- assignment outline 457 3 INTRODUCTION TO THE REPORT The integration of science and management is a highly desirable goal for both the management and scientific communities. There are many obstacles to this goal, but some particularly important challenges include: 1. The need to train students who are familiar with both science and management, and who can balance the tendency of science to be focused and rigorous, with the need for management to consider many factors, many of which are difficult to control or isolate. 2. The difficulty in collecting and synthesizing an overwhelming amount of scientific literature that is scattered across many sources. 3. The challenge in both science and management to consider: a. A wide diversity of interacting goals and constraints, and the potential for trade- offs and win-win scenarios b. Changes in patterns and controls over biotic and abiotic factors over space and time This report is a result of the collaboration between the Yolo County Parks and Resources Department and the Restoration Ecology Class (ENH 160) at University of California, Davis. The Yolo County Parks and Resources Department graciously agreed to serve as a test case for this project, and set the stage for it by: - providing a list of key questions, topics, challenges, organisms, and ecosystem services of concern - providing access to lab students for monitoring and observational activities - lecturing in the laboratory section about the challenges of implementing restoration projects, and providing background information on Grasslands Regional Park and its management goals. The overall goal of class project was to develop a restoration handbook for the Grasslands Regional Park vernal pool complex. Each student was in charge of a different restoration goal (a key organism or vernal pool characteristic), and was instructed to do a thorough literature search to determine: - the status of that organism or vernal pool characteristic - the key ecological and socio-economic controls over that goal - successes and failures of previous management/restoration attempts - key gaps in knowledge - possible funding sources for management and restoration of their goal Using this information, each student was instructed to design a management/restoration plan for their goal. Our hope is that these individual reports provide a handy literature review on key individual restoration and management goals. These individual projects were just the start of the instructional, and project-wide goal. Our ultimate goal was to develop some overall management options based on all of these goals—coming up with alternative management scenarios that carefully stressed the multiple goals they could achieve, and the tradeoffs in other goals. To do this, after the individual phase of the project was completed, each student presented a summary of their individual projects. We then spent a few class sessions integrating all of the individual projects to come up with management scenarios that could attain these multiple goals. Results of these discussions can be found in the “project synthesis” section. In addition, the end of each student’s individual report includes a revised management plan to encompass their goal, in addition to a broader suite of goals. A full description of the students’ assignment can be found in the Appendix. 4 While this report is far from perfect or complete, it should be a handy guide for both science and management- providing literature reviews on many important topics in California’s vernal pools, and pointing to some key holes in our scientific understanding that will aid with the implementation of restoration and management programs. The management recommendations are very preliminary due to time limitations, but the literature reviews and lists of trade-offs should provide important information for those managing California vernal pools. Overview of our project on the Yolo County Grasslands Regional Park: Yolo County’s Grasslands Regional Park is an approximately 640 acre area located roughly 2 miles southeast of Davis at the southwestern corner of Yolo County. The Grasslands Park consists of a variety of habitat types and management areas, including vernal pools, grasslands, and an oak planting area that are managed primarily for conservation of plant and animal species and recreation. 5 Aerial photo of Yolo County Grasslands Regional Park. Our class project focused on the 184 acre vernal pool management area, which includes the vernal pools, swales and bordering mesic grassland. The class focused on 10 naturally occurring pools and the 5 pools that were created as additional habitat for two listed vernal pool grass species. The general management goals and requirements of the vernal pool complex include: - conserve key federal and state listed species - enhance populations of a vernal pool grass species endemic to Grasslands Park (Crampton’s tuctoria) and a listed vernal pool grass species (Colusa grass) - control invasive plant species - enhance native diversity - manage surrounding upland grasslands (e.g. invasive plant control, burrowing owl habitat, recreation) without impacting the vernal pools Our overall class goals included: 1. How do we manage existing vernal pools to support a broad array of native species and minimize invasives over time? (dealing with high annual variability in rainfall, and potential climate change) a. What are the key ecological processes needed for the site to sustain itself over time? b. What are the requirements of different target species, and can the existing vernal 6 pools meet these (individually, and as a complex of pools)? c. Given the required management goals, which other species are most likely to be promising restoration goals? d. How do upland habitats need to be managed to support vernal pool goals (without compromising upland restoration goals)? e. Can the vernal pool complex at this site maintain itself over the long-term, or is there a need to create broader-scale links with other vernal pools across the region? Two of the natural vernal pools in April 2010 (Pool 9B on the left, pool 9A on the right). 2. What is the potential role of recreated vernal pools in supporting species currently on- site (particularly endangered/ threatened), as well as other species not currently on site? a. Is there a need for different depths/inundation periods to be present on site? b. What shape should these pools be (deep pools? Shallow swales?) c. What size should they be? d. Where should they be placed? (Are there key spatial gaps in current vernal pool distribution needed for gene flow/pollination/dispersal, etc.?) e. Will the creation of new vernal pools potentially create more problems? (altered hydrology, increased invasion among pools, etc.)?