death decline spiral pictures 2 (1)

Decoding Death:Connecting climate and growth to

predict tree mortality across

species

Heidi SwansonBiology Senior Seminar

April 16, 2015

I. Introduction to tree longevity

II.Growth/mortality relationships

III.Drought/growth relationships

IV.European Buckthorn

V.Final thoughts

OUTLINE

2

WHY IS TREE MORTALITY

IMPORTANT?

• Climate change (Adams et al. 2006)

• Forest ecotones?

• We need models!

• Long-term

• Tree mortality is (hopefully) predictable

3

4

(sometimes)

unluckylucky

5

Trees can die

catastrophically…

7http://news.ubc.ca/wp-

content/uploads/2013/05/601474937_1f726929ed_o.j

pg

…or they can die

after a long, hard

battle.

8

https://cla.umn.edu/news-

events/story/evidence-suggests-

california%E2%80%99s-drought-worst-1200-

Trees struggle through

droughts. Water is

crucial for survival,

though some species

are more tolerant/use

water more efficiently.

9Piñon trees after 2001-2002

drought

Piñon trees before 2001-2002

droughthttps://collapseofindustrialcivilizatio

n.files.wordpress.com/2013/01/pin

onpinedieoff.jpg


drought




onpinedieoff.jpg

Can we

figure out

how many

are going to

make it?

A few

rugged

survivors

CLIMATE MORTALITY

11

(temperature,

drought)(who dies???)

?????

?????CLIMATE MORTALITY

12

(temperature,

drought)(who dies???)

???


drought




onpinedieoff.jpg

Can we

figure out

how many

are going to

make it?

A few

rugged

survivors


IMPORTANT?



• We need models!

• Long-term

• Tree mortality is (hopefully) predictable

15


IMPORTANT?



• We need models!

• Long-term

• Tree mortality is (hopefully) predictable but poorly understood

16

NOT ALL TREES WILL KICK THE

BUCKET…

17(Pedersen et al.

1999)


drought




onpinedieoff.jpg

What’s

different

about them?

A few

rugged

survivors

GROWTH MORTALITY

19

(a proxy for vigor)

GROWTH – A USEFUL

(who dies)

SYMPTOM

WHAT AFFECTS HOW

TREES GROW?

• Competition, disturbance,

climate…

• Structural limitations (Koch et al. 2004)

20

CLIMATE GROWTH

21

(a proxy for vigor)

CLIMATE – A USEFUL

(temperature,

drought)

PREDICTOR

GROWTH MORTALITY

22

(a proxy for vigor)

GROWTH – A USEFUL

(who dies)

SYMPTOM

CLIMATE GROWTH MORTALITY

23

(a proxy for vigor)

GROWTH – A USEFUL

(temperature,

drought)(who dies)

INTERMEDIATE


24

(a proxy for vigor)

GROWTH – A USEFUL

(temperature,

drought)(who dies)

INTERMEDIATE

WHAT AFFECTS HOW

TREES GROW?

• Competition, disturbance, climate…

• Structural limitations (Koch et al. 2004)

25

26

GROWTH PATTERNS: CONVENTIONAL WISDOM

Growth slows with increasing size and

age? (Bowman et al. 2013)

27




28




r

r2

r3

29

….Or unconstrained growth across

lifespan? (Stephenson et al. 2014)

GROWTH PATTERNS: HYPOTHESIS OF

THE RENEGADES

30

….Or unconstrained growth across

lifespan? (Stephenson et al. 2014)

GROWTH PATTERNS: HYPOTHESIS OF

THE RENEGADES

403 different

species?!?

Six

continents?!?

673,046 trees?!?


32

(a proxy for vigor)

GROWTH – A USEFUL

(temperature,

drought)(who dies)

INTERMEDIATE

(BUT NOT

FLAWLESS)

crude

INTER-SPECIES TRADEOFFS

Loehle et al. (1988)

• Slow-growing species

often live longer than

fast-growing pioneer

species in the absence

of drought

• Growth/defense

tradeoffs

33

34

Between

individuals

(within the

same

species):

Between

species:

Slow-growing,

Long-lived

Fast-growing,

Short-lived

Fast-growing,

?????

Slow-growing,

?????

Slow-growing,

?????

Fast-growing,

?????

vs

vsvs

IMPORTANT QUESTIONS

• How do different growth rates between individuals within a species affect mortality/longevity?

• Can we use climate variables to predict species-specific mortality?

35





V.Final thoughts

OUTLINE

36

BIGLER AND VEBLEN (2009)

Do fast-growing

conifer

individuals live

shorter lives than

slow-growing

individuals of the

same species?

37http://en.es-static.us/upl/2011/03/tall_short_trees.jpg

METHODS

• Roosevelt National Forest (Colorado); Davos, Switzerland

• Sampled all standing dead

• Subalpine fir (70 trees), Engelmann spruce (50 trees), Norway spruce (41 trees)

• Two increment cores per tree

• Crossdating

38http://www.planat.ch/uploads/pics/p0134_02.jpg

METHOD: RADIAL

INCREMENT

MEASUREMENTS

39Xylem rings

Vascular

cambium phloem

bark

0.4

mm

0.2

mm

0.3

mm

0.5 mm

0.6

mm

0.4 mm

0.4 mm

Ring # Width

0 0.3

1 0.4

2 0.5

3 0.2

4 0.6

5 0.4

6 0.4

40

Year Width

2008 0.3

2009 0.4

2010 0.5

2011 0.2

2012 0.6

2013 0.4

2014 0.4

HOW DO WE DATE DEAD

TREES?

41

• Cross-dating

HOW DO WE DATE DEAD

TREES?

• Cross-dating

42

HOW DO WE VERIFY OUR

DATES?

Quality control – with software

Identify errors in measurement

• Correlation analysis of each successive segment

• Test segments of series against same segments of master dating series created from all other series

12x magnification of European buckthorn rings

43

SIZE OF SHORT-LIVED VS. LONG-LIVED

INDIVIDUALS

44

EFFECTS OF EARLY GROWTH RATES

ON LONGEVITY

45

46

Between

individuals

(within the

same

species):

Between

species:

Slow-growing,

Long-lived

Fast-growing,

Short-lived

Fast-growing,

short-lived

Slow-growing,

long-lived

Slow-growing,

?????

Fast-growing,

?????

vs

vsvs

IRELAND ET AL. (2014)

Are early growth

rates in quaking

aspen predictive

of longevity?

47http://99viral.com/wp-content/uploads/2014/04/Quaking-Aspen.jpg

METHODS

• Kaibab National Forest – northern Arizona

• Aspen/fir/pine forests

• Increment cores from both living and standing dead overstory

aspen

48

GROWTH RATES FOR LIVE VS. DEAD

TREES

49

Live

Dead

EARLY AND LIFETIME GROWTH

RATES FOR LIVE VS. DEAD TREES

50

First 50 years

Lifetime

51

Between

individuals

(within the

same

species):

Between

species:

Slow-growing,

Long-lived

Fast-growing,

Short-lived

Fast-growing,

short-lived

Slow-growing,

long-livedSlow-growing,

short-lived

Fast-growing,

long-lived

vs

vs vs


II. Growth/mortality relationships

III. Drought/growth relationships

IV. European Buckthorn

V. Final thoughts

52

OUTLINE


53

(a proxy for vigor)

GROWTH – A USEFUL

(temperature,

drought)(who dies)

INTERMEDIATE

WYCKOFF AND BOWERS

2010

• Three sites: Maplewood State Park, Glacial Lakes State Park, Sibley State Park

• Bur oak

• 52 trees for climate growth

• 33 dead and 30 living trees for growthmortality

54

STUDY SITES

Maplewood State Park,

Glacial Lakes State Park,

Sibley State Park

55

56

PDSI

PALMER DROUGHT SEVERITY

INDEX (PDSI)

CLIMATE GROWTH

57

In drought

conditions,

growth rates

are low.

WETDRY WETDRY

58

DIVERGENCE IN GROWTH: LIVING

VS. DEAD TREES

GROWTH MORTALITY

59

When growth

rates are low,

the probability

of mortality is

high.


60

(a proxy for vigor)

GROWTH – A USEFUL

(temperature,

drought)(who dies)

INTERMEDIATE

CLIMATE MORTALITY

61

Prediction: In

drought

conditions, the

probability of

mortality is

high





V.Final thoughts

OUTLINE

62

EUROPEAN

BUCKTHORN

63

• Non-native, pervasive

species in MN

• Will its spread be

facilitated by climate

change?

• No studies on

buckthorn growth

response to climate

METHODS

Destructive removal

• 30 – 40 European

buckthorn trees per

site

• Ginseng Road Farm,

Niemackl Lake Park,

Monson Lake State

Park

64

METHODS

65

METHODS

66

METHODS

Dating

• Initially assume

last year = 2014

for all trees, plot

ring width

increments in

Excel for internal

cross-dating

67

0

0.5

1

1.5

2

2.5

3

3.5

4

1996 2001 2006 2011

Tree 1

GRF1b1 GRF1b2 GRF1a1 GRF1a2

68

0

0.5

1

1.5

2

2.5

3

3.5

4

1995 2000 2005 2010

Tree 1

GRF1a1

GRF1a2

GRF1b1

GRF1b2

METHODS

• Use COFECHA to identify false/missing rings, obtain

accurate dated series

69

METHODS

Detrend with ARSTAN

Remove age-related growth trends and retain climate signal

70http://www.ltrr.arizona.edu/~sheppard/workshop/quant.gif

71




METHODS

Detrend with ARSTAN

Remove age-related growth trends and retain climate signal

72http://www.ltrr.arizona.edu/~sheppard/workshop/quant.gif

73

y = 0.0234x + 0.983R² = 0.3566

0

0.2

0.4

0.6

0.8

1

1.2

1.4

-8 -6 -4 -2 0 2 4 6

Rad

ial g

row

th (

detr

en

ded

)

Palmer Drought Severity (PDSI) Index

July Drought (PDSI) versus Detrended European Buckthorn Growth

DRY WET

74

SEEDLING PLOTS

75-0.2

0

0.2

0.4

0.6

0.8

1

-3 -2 -1 0 1 2 3 4 5

Re

lati

ve G

row

th R

ate

PDSI Index

Ash

Bur Oak

EuropeanBuckthorn

DRY WET

Drought vs lifetime average growth across

species

76

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0246810121416

Ave

rag

e r

ad

ial g

row

th (

mm

yr-

1)

Years before coring

Average annual radial growth trends for living and recently dead trees

Dead Live

Live vs dead: no

gap

Live vs dead: wide gap

77

y = 0.0199x + 0.0849R² = 0.8236

y = 0.0309x + 0.0324R² = 0.8701

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0 2 4 6 8 10 12 14 16

Lif

eti

me a

vera

ge g

row

th r

ate

(m

m y

r-1)

Diameter (DBH)

Lifetime Average Growth Rates of Live and Dead Trees Across Sizes

Dead Live





V.Final thoughts

OUTLINE

CONCLUSIONS

• No universal growth-mortality relationship

• Tradeoffs between growth and longevity

• Species differ in their drought response

• Buckthorn more sensitive to summer drought (relative to

other species) than expected

79

FUTURE RESEARCH?

• What makes buckthorn respond the way it does?

• Compare buckthorn’s response to that of native species

• Other sites?

• Seasonal responses?

• How will differences in drought response between species

affect their competitive interactions?

80

ACKNOWLEDGMENTS

• Peter Wyckoff

• UMM Biology faculty

• Friends & family

81

82

QUESTIONS

death decline spiral pictures 2 (1)

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