N. Stephenson 10/2015 from Beetle Rock

Drought Mortality: Implications for carbon and fuelsJohn Battles, ProfessorUC Berkeley

DX site: Sequoia Kings Canyon National ParksUSGS Collaborators: Nate Stephenson and Adrian Das

Dead tree cycle CO2

growth

death

CO2

Dead treeLive tree

CO2

1000+ hour fuel

Fate of standing dead trees 1. Decay2. Degrade3. Fall

Species (and size) differences in fall rates

Wood Decay Rates

Dead tree cycle CO2

growth

death

CO2

Dead treeLive tree

CO2

1000+ hour fuel

Time (years)

pre 2017

2027

2037

2047

2057

2067

Biom

ass

(tons

/acr

e)

121

200

350

500

650

800

915

Standing dead tree1000 hr fuel

Live tree

2014-16 mortality event

Dead Tree Cycle: Preliminary modelSequoia Kings Canyon National Parks

2014-2017 mortality event

31% loss of live tree biomass

330% increase in dead tree biomass

2014-2017 Mortality

Fuel Distribution2017 vs 2030By 2030

1000+ hour fuel load doubles

75% of the plots > 100 tons/ac

90% have a least 60 tons/ac

All plots with some 1000+ fuel

Quantifying theoretical risk

The scale of present tree mortality is so large that greater potential for “mass fires” exists in the coming decades…

Stephens et al. 2018Bioscience

Stephens et al. 2018

FOREST RECOVERY AFTER DROUGHT MORTALITY: PRELIMINARY RESULTS FROM SUMMER 2017

Lauren Cox, PhD student, UC Berkeley

Seedlingsstems < 4.5 ft

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

PLUM BRTN CGH YOMI YOPI SIERRA SEKI MTH

Seed

lings

per

acr

e

*

* Data shared by Sharon Hood

0

100

200

300

400

500

600

700

800

900

PLUM BRTN CGH YOMI YOPI SIERRA SEKI MTH

Sapl

ings

per

acr

e

Saplingsstems ≥ 4.5 ft ht, < 4 in DBH

*

* Data shared by Sharon Hood

Shrub Cover

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

PLUM BRTN CGH YOMI YOPI SEKI MTH

Shru

b co

ver

Yosemite Mixed Conifer Site

0

20000

40000

60000

80000

100000

120000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Stem

s pe

r ac

re

Percent shrub cover

Sequoia-Kings CanyonTrees: stems ≥ 4 in DBH

0

10

20

30

40

50

60

70

80

White fir Incense-cedar Sugar pine Ponderosa pine CA black oak

Basa

l are

a (f

t2ac

-1)

LiveDecay 1

Sequoia-Kings CanyonSaplings: stems ≥ 4.5 ft ht, < 4 in DBH

0

20

40

60

80

100

120

140

160

White fir Incense-cedar Sugar pine Ponderosa pine CA black oak

Sapl

ings

per

acr

e

Sequoia-Kings CanyonSeedlings: stems ≤ 4.5 ft ht

0

100

200

300

400

500

600

700

800

900

1000

White fir Incense-cedar Sugar pine Ponderosa pine CA black oak

Seed

lings

per

acr

e

Yosemite DX SitesSeedlings: stems < 4.5 ft ht

0

2000

4000

6000

8000

10000

12000

14000

White fir Incense-cedar Sugar pine Ponderosa pine Douglas-fir CA black oak

Seed

lings

per

acr

e

YOPIYOMI

Yosemite DX SitesSaplings: stems ≥ 4.5 ft ht, < 4 in DBH

0

5

10

15

20

25

30

35

White fir Incense-cedar Sugar pine Ponderosa pine Douglas-fir CA black oak

Sapl

ings

per

acr

e

YOPIYOMI