1.0

0.8

0.6

0.4

0.2

0.0

Frac

tion

of m

ass

iden

tifie

d

1.0

0.8

0.6

0.4

0.2

0.0

Cum

ulat

ive

fract

ion

iden

tifie

d

12080400Number of VOC species identified

1.0

0.8

0.6

0.4

0.2

0.0200150100500

Ion m z (Th)

C

anop

yC

anop

yLi

tter

Log

Log

Can

opy

Can

opy

Can

opy

Can

opy

Duf

f C

anop

yC

anop

yLi

tter

Log

Can

opy

Can

opy

Litte

rdu

ffLi

tter

Litte

rC

lean

Cle

anD

irty

Dirt

yC

lean

Cle

anC

lean

Dirt

yD

irty

Dirt

y C

anop

yC

anop

y Ex

cels

ior

Exce

lsio

rD

ung

Peat

Ric

e st

raw

Bear

gra

ssJe

ffrey

pin

e ba

rkBu

ildin

g m

ater

ial

Ponderosapine

Lodgepolepine

Engelmannspruce

Douglasfir

Subalpinefir

Loblollypine

Manzanita

Chamise

Sage

Juniper

Ceanothus

Other

a

b

Cumulative fraction of mixing ratio (ppbv)

Cumulative fraction of mass

c

-1