lter 2015 levine

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Using Bayesian hierarchical models to estimate forest demographic processes Carrie R. Levine 1 , Natalie S. van Doorn 1,2 , and John J. Battles 1 1 Environmental Science, Policy and Management, UC Berkeley 2 US Forest Service Pacific Southwest Research Station LTER ASM 2015 Working Group: Sources of Uncertainty in Ecosystem Monitoring 1 September 2015

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Page 1: Lter 2015 levine

Using Bayesian hierarchical models to estimate forest demographic processes

Carrie R. Levine1, Natalie S. van Doorn1,2, and John J. Battles1

1 Environmental Science, Policy and Management, UC Berkeley2 US Forest Service Pacific Southwest Research Station

LTER ASM 2015Working Group: Sources of Uncertainty in Ecosystem Monitoring

1 September 2015

Page 2: Lter 2015 levine

Advantages of Bayesian models for monitoring

Model accounts for variation at multiple scales.• This example: The likelihood for the entire community is

the product of the species level probability and the community level probability.

• Other possible sources: over space, over time, uneven sampling intervals, uneven sample size, etc.

Scant observations for rare species are informed by the overall community mean and the estimates for individual species and the overall community are more robust than with a non-hierarchical model.

Page 3: Lter 2015 levine

RGR[i,j](log norm dist)

p[i](log norm dist)

μ(unif dist)

τ.with(gamma dist)

τ.btw(gamma dist)σ Species [i]

Community

Individual [i,j]

Hierarchical model structure:Relative growth rate (% yr-1)

LevelsModel

for j IN 1:ind

for i IN 1:spp

Page 4: Lter 2015 levine

0 1 2 3 4 5 6 7 8 9 100

0.2

0.4

0.6

0.8

1

1.2

1.4 1957-...G

row

th ra

te o

f tre

es >

24 c

m D

BH

(% y

r-1)

Douglas-fir

Comm. meann = 546

Relative growth rate for an old-growth Sierra Nevada mixed-conifer forest

White fir

Incense

cedar

Ponderosa

pine

Sugar pine

Page 5: Lter 2015 levine

n = 3390n = 3339n = 3792

Relative growth rate for an old-growth Sierra Nevada mixed-conifer forest

Page 6: Lter 2015 levine

Constraining estimates of rare species using the community-level mean

Example: Mycorrhizal species abundance measured pre- and post-fire

Species Number

Cha

nge

in a

bund

ance

(OT

units

)