L ki g b
li
Di
b nce effects
ff
d substrate
b
li
i i
y d climate:
Disturban
limitations
beyond
and
Looking
t ib ti
iin arctic
ti an
d temperate
t p t alpine
lpi ecosystems
y t
on ttree di
distributions
nd
D
Carissa D.
1
Brown ,
F
Jillll F.
2
hnstone ,
Joh
d
and
1
ll d
Markk Vellend
1Université de Sherbrooke
Sherbrooke, Sherbrooke
Sherbrooke, Canada; 2Universityy of Saskatchewan
Saskatchewan, Saskatoon
Saskatoon, Canada
W expect
t will
ill expand
i di
t ib ti northwards
th
d and
d upwa
d as environmental
i
t l constraints
t i t on tree
t
t bli h
t and
d survival
i l llessen
We
p t th
p d th
p rds
thatt fforests
their
distribution
establishment
Forest ecosystems
y
in the northern Appalachian mountains
conifer-dominated
transition
hardwood
t
iti from
f
h d
d to
t conifer
if dominated
d i t d stands
t d
with increasing
g elevation.
elevation With climate warming,
warming
g, we
d
d fforests to shift
hif upwards
d on alpine
l i slopes
l
expect h
slopes.
hardwood
SUBSTRATE
DISTURBANCE
g maple
p
Sugar
p e
Black
spruce
Bla k sp
W compared
d availability
il bili y and
d
We
p d seed
dli g establishment
bli h
bl k
seedling
off black
iin stands
d off varying
fire return
spruce
p
yi g fi
i
l using
i g experimental
l
interval
p i
p l
y g in
h areas varying
within
manipulations
h i naturall fi
i
fire hi
histories
their
histories.
Wee initiated
t ated a reciprocal
ec p oca transplant
t a sp a t
experiment
e
pe e t of
o both
bot seed and
a d soil
so
to disentangle climate versus
substrate limitations on sugar
maple elevational range
expansion
expansion.
Beyond
the range
y
g
g edge
g
Range
Within
t
the
e range
a ge
Warming
g summer temperatures
p
are contributing
g to
sub-Arctic
increases in fire
f activity in the
h western sub
b Arctic. Stands
d
that
adapted
historic
th t have
h
d t d to
t regenerate
t under
d hi
t i fire
fi cycles
l
are now experiencing
p
g novel disturbance regimes.
regimes
g
See Brown & Johnstone
Johnstone. 2012
2012. Forest Ecology and Management 266: 34
34-41
study.
41 for full study
Mature forest: Has not
burned for >80 yyears.
Long-interval
Long interval fire: 90 years
since p
previous fire.
Short-interval
Short interval fire: 15 years
since
previous
i
i
fifire.
S d
Seed
ding
di
g
experim
ments:
M l planted
l
d
Maple
within
ithi its
it
atu al range
a ge
natural
((i.e.,
(i , ffavourable
bl
climate))
8
6
4
2
0
1 0
150
Sp
Spru
uce
e se
see
ed
dlin gs p
pe
err m 2
Sugar
S g maple
pl
i
recruitment
was
d d when
h planted
d on
reduced
pl
b
ffrom b
substrate
beyond
y d
maple
pl ’s current range,
g
maple’s
range
d favourable
f
bl
even under
li
i conditions
di i
climatic
conditions.
M
Ma
ap
ple
e sse
ee
ed
dliin
ng
gss pe
perr po
pott
10
100
50
0
within
d
seed
edge
seed
soil from
within
Acer
range
A
within
seed
edge
seed
soil from
edge of Acer
range
within
seed
edge
seed
soil from
beyond Acer
range
g
Within the current distribution of sugar
g maple,
maple
p where climatic conditions are conducive to
establishment
t bli h
t and
d survival,
survival
i l substrate
b t t effects
ff t outweigh
t i h climatic
li ti controls
t l on recruitment
recruitment.
it
t As
A climatic
li ti
conditions become more favourable at higher
g
elevations
elevations,, these substrate constraints will like result in a
time lag
l prior to range expansion
expansion.
mature
forest
long
longinterval
fire
fi
short
shortinterval
fire
fi
mature
forest
Fire history
long
longinterval
fire
fi
short
shortinterval
fire
fi
h seed
d was added,
dd d,
When
added
bl k spruce
d
recruitment off black
increased
p
h
lb
d stands
d b
d
in short-interval
burned
but remained
d Recruitment was
scarce in mature fforest stands.
stands
f short ffire
constrained byy seed availabilityy after
intervals, and substrate in mature stands.
stands
return intervals,
Recruitment was drasticallyy reduced following
g two closelyy time fires.
fires When the most recent fire occurs
b f
before
the
th regenerating
ti stand
t d can reach
h reproductive
d ti maturity
maturity,
t it closely
closely-timed
l l timed
ti d fires
fi interrupt
i t
t the
th cycle
l off
stand self replacement
stand-self
p
. The indirect climate effects caused byy a change
g to the fire regime
g
mayy initiate
vegetation shifts
h f in the
h opposite direction
d
than
h would
ld happen
h
due
d to climatic
l
change
h
alone
alone.
l
Indirect
d ect o
or non-climatic
non
o cclimatic
at c factors
acto s may
maay have
haa e a greater
g eate cont
co trol
o o
over
e
er species
spec es distrib
distributions
d st buttions
o s than
t a direct
d ect climatic
c at c e
effects
ects
Acknowledgements: National Science and Engineering Council of Canada
Canada, International Polar Year
Year, The W
W. Garfield Weston Foundation
Foundation, Arctic Institute of North America,
America No
orthern Scientific Training Program,
Program Northern Research Institute
Institute, International Association of Wildland Fire,
Fire PPS Arctic
Arctic, Université de Sherbrooke,
Sherbrooke University of Saskatchewan