Tanoak: conservation of an at risk tree

Richard Cobb, Joao Filipe, Katy Hayden, Ross Meentemeyer, Yana Valachovic, Ted Swieki,

Chris Gilligan, Everett Hansen, Susan Frankel, Matteo Garbelotto, Dave Rizzo

Perspectives and challenges

• Frederica Bowcutt : Tanoak, a persecuted species • John Shelly : changes in resources perspectives • Thomas Brown : traditional resource perspectives • Whalen Dillon: Comprehensive risk assessment

Ecological value and resources

•Richard Dodd (Jessica) : basic genetic understanding: bias of understudied species • Jessica Wright : Insect pollinators , scratching the biodiversity iceberg • Katy Hayden: finding resistance

Learning from failure

• Forest decline in N. America: Sudden Oak Death is a familiar threat

• Chestnut: management increased pathogen spread

• Eastern hemlock: management (cutting) increased tree decline

The twin traps of overtreatment and therapeutic nihilism*

• What are the management goals?

• Invaded Vs. uninvaded lands

• Goal: maximize tanoak resiliency and biodiversity

* Hippocratic oath

Sudden oak death impacts are greater in large trees

Sudden oak death caused mortality increases with tanoak size*

Sudden oak death: stands quickly lose tanoak biomass

*Davis et al 2010 *McPherson et al 2010 *Cobb et al. 2012

A toolbox for tanoak

conservation

• Change the conditions of disease:

– Reduce infection rate

– Reduce mortality rate

– Exclude pathogen

Local pathogen reduction

Valachovic et al. Southern Humboldt Unpublished data

0 1 2 3 4 5

Pro

bab

lity

of

infe

cti

on

0.0

0.1

0.2

0.3

0.4

0.5

Treated

Untreated

Survey (years)

13,000

800

10 sites,

229 trees

Garbelotto et al., unpublished

Preventative treatments

Garbelotto et al. 2008 Swiecki and Bernhardt 2008

Agriphos® (phosphonate) treatments reduce pathogen growth in tanoak and coast live oak

Models: forecasting spread and efficacy

20

40

60

80

100

0 20 40 60 80 100

Removed bay laurel (% of bay population)

Tan

oak y

ears

to

50%

declin

e

80% Protected tanoak

40%

0%

Cobb et al. 2012

Filipe et al. unpublished

Pro

po

rtio

n o

f ta

no

ak

• Plan ahead; slowing the spread saves tanoak, reduces impacts, and saves time/$$

• Act now to protect specific stands, trees

• Do not move infected plants

• Avoid doing to much; loss of genetic based resistance

Strategy: Uninvaded areas

Mendocino county

• Agriphos ®, host density reduction, planting of resistant stock

• Disease selects for more resistant individuals: do not cut/remove lone surviving tanoak

• Manage to reduce impacts (human suffering)

Strategy: Invaded areas

Big Sur

Acknowledgements

• Institutions and Organizations:

• UC Davis, UC Berkeley, UNC Charlotte, Univ Cambridge, UCCE, Oregon St., USDA Forest Service PSW, Phytosphere

• Funding: NSF-EEID, USFS, Moore Foundation, DEFRA, BBSRC, and USDA-APHIS, NRC

• People: Rizzo, Garbelotto, and Meentemeyer lab groups

K. Frangioso