Bees and Flowers in California Forests

Transcription

1 Bees and Flowers in California Forests By: Gordon Frankie, Robbin Thorp, Rollin Coville, Sara Leon Guerrero, Jaime Pawelek, Mary Schindler, Marylee Guinon, and Mark Rizzardi University of California Berkeley & Davis, Humboldt State University

2 Outline General characteristics of native bees Early bee-flower work at UC Berkeley Oxford Tract Statewide survey of bee-flower relationships in urban California gardens: use and implications Forest Bees of Yosemite National Park

3 Native Bee Diversity ~ 4,000 bee species native to the United States ~1,600 bee species are found in California 5,000+ flowering plant species (angiosperms) in California Centris rhodopus Ceratina spp.

4 Native Bee Biology, Behavior & Ecology Much variation among bee species Each bee species has its own story Fertile ground for research and outreach

5 Native bees have evolved with native flowering plants in California and worldwide

6 Agapostemon texanus Melissodes sp. Hylaeus sp. Megachile sp.

7 Xylocopa varipuncta Trachusa bequarti Halictus sp. Andrena nigrocaerulea

8 CA Native Bee Ecology Most native bees are solitary nesters ~ 70% of bees nest in the ground, 30% in preexisting cavities Nesting implications for habitat gardening

9 Pre-existing Cavity Nesters: Leaf cutters in wooden trap nests

10 CA Native Bee Ecology Three things that bees need: pollen, nectar, and mating Only females sting! Three types of pollen collection, depending on bee taxa Xylocopa varipuncta male

11 Pollen collected on legs Pollen collected under the abdomen Pollen collected in the crop

12 Early Urban Bee Work: UC Berkeley Oxford Tract Urban areas can serve as habitat for native and honey bees Research by our lab has found 88 bee species in Berkeley (83 native bee species) ~60 bee species in Oxford Tract Oxford Tract Garden 2005

13 Oxford Tract Evaluation Garden Goal 1: Evaluate basic bee-flower relationships Goal 2: Monitor diversity and abundance of bee species through time:2003-present Goal 3: Evaluate optimal plant management methods for vigorous flowering Goal 4: Use evaluations for habitat gardens statewide

14 Oxford Tract July 2003

15 Oxford Tract 2008

16 Oxford Tract Evaluation Garden Major Findings Certain plant families highly attractive to bees Asteraceae, Lamiaceae, Boraginaceae (Hydrophyllaceae) Polygonaceae, Rosaceae Osmia sp. on Phacelia campanularia Anthophora urbana on Phacelia campanularia

17 Statewide Survey 15 cities surveyed ~50 gardens throughout CA Variety of garden types: schools, botanical gardens, residential, and a cemetery

18 Ukiah

19 Major Bee-Flower Findings Aerial collections of bees on flowers: Current bee species count: approaching 400 bee species Current host plant types: ~500 plant types Bee species, location, date, and plant host info added to Access database Relatively high bee species diversity in most cities

20 Bee Species from 5 Surveyed Cities Location Families Genera Species Ukiah 5 28 Sacramento 5 23 Berkeley 5 25 San Luis Obispo (110) 82 (90) 88 (95) 99 (115) La Cañada Flintridge (near Pasadena) (130)

21 Bees of Yosemite Nat l Park Report by: Terry Griswold, Harold Ikerd, Erica Stephens USDA-ARS Bee Biology & Systematics Lab Utah State University Logan, Utah

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23 Background of Survey Few studies on bees conducted in CA forests Moldenke (1976) in a preliminary study in CA suggested there was rich fauna in Sierra Nevada. His numbers were estimates. Pinnacles Nat l Park (small site) has 400+ spp. of bees (Messinger and Griswold 2003) Yosemite study ( ): first comprehensive and systematics study of S-N bees

24 Main Goals 1. Develop baseline data for future monitoring of bee pollinator pops. 2. Provide inventory of bee fauna 3. Determine spatial & temporal patterns of bee fauna (e.g. elevation & seasonal) 4. Determine bee-plant relationships

25 Collections, Monitoring Pan traps used at each site, 9-3pm Aerial collection off flowers Sites distributed from 1,850 to 11,000 1,043 collector days, sampling 418 sites (variable types)

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27 Fire Effects (Burns) & Bees Challenging to deal with many variables Variables: age of burn, size, intensity of burn, vegetation type, slope, recolonizing plant spp.

28 Bee Sampling Processing Specimens to USDA Logan Bee Lab Taxonomic determination limited at times. Some bee groups need more taxon. work. Revisions needed. Some spp. treated as morphospecies when good names could not be determined (Taxonomy is a problem for all such studies)

29 Inventory 596 bee spp. Recorded to date ~38% of CA bee record (1,600); 15% of U.S. record (4,000) All 6 families of bees found in U.S. 44 genera of bees (=41% of U.S. bee genera)

30 Inventory cont. 81% of bees were solitary; ea. female nests independently Social bees (7%): Bumble bees; 14 of 27 CA spp.; 2 sweat bee groups; honey bee Cleptoparasitic bees: 12% A few rare spp. recorded

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32 Nesting Ground nesters and cavity nesters Bombus edwardsii in bark of giant sequoia Gregarious nesting Carpenter bees nesting in snag

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34 Temporal Bee Patterns Composition of bee spp. differed sign. between years, esp. noticeable with Bombus spp. Other groups need more analysis

35 Fire Effects Study suggests that burns (of various ages) are refuges of bee abun. & diversity 1-6 yr old burns best for prime bee habitat Burn areas have good flowering host plants for bees

36 Floral Relationships Bees recorded on 539 plant taxa in Yosemite Bees vary greatly in degree of specialization in pollen choice: 84 spp. specialized Rest are generalists

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38 Conclusions to Yosemite Study 1. First large landscape study of bees in CA 2. First systematic study of bees of this scale in Sierra Nevada, or in any other part of CA 3. First opportunity to understand bee-plant relationships in S-N pollinator communities, and how communities are organized spatially and temporally

39 Conclusions cont. 4. Interpretive park rangers will use findings to share with public. Lots of public interest. 5. Many questions generated for future studies, esp. with regard to fire (burn) habitat for bees 6. Some areas in park need more collecting

40 THANK YOU New book Bees and Blooms in Urban California * by Frankie, Thorp, Coville, and Ertter Heyday Books Fall *Title pending