From restoration to resilience ecology
Rapid ecosystem shifts, landscape disturbance and
climate change
Don Falk, University of Arizona
School of Natural Resources and the Environment
AGU GC24A, December 2013
Ecological change driven
by climate alone operates
on decadal time scales
• Poleward migration ~10 –
80 (160) km century-1
• Upslope movement ~ 60 –
100 m century-1
Parmesan and Yohe 2003; Chen et al. 2011;
Notaro et al. 2012
In contrast, severe large-scale
disturbances can trigger abrupt ecological
change with more unpredictable
outcomes than climate alone
Giant pyrovortex, 2011 Las Conchas Fire: Craig Allen, USGS.
Jemez Mts fire severity composite: Andi Thode, NAU.
(How) will ecosystems recover after
severe disturbance, and what can and
should managers do?
1. Recover quickly to pre-fire condition
(“resilient”).
2. Recover slowly (decades, centuries) to
pre-fire condition.
3. Become entrained in a new state (e.g.
shrub-dominated, chaparral; “tipping
point” type conversion)
Deconstructing “resilience”
Hobbs and Suding 2009
“The capacity of an ecosystem to recover to its
pre-disturbance composition, structure, and/or
function over time.”
• Note the similarity to SER’s definition of
“restoration”
• Implicitly n-dimensional (i.e., multiple
response variables), scale dependent
Unpacking “scaled resilience”
1. Spatial scale of disturbance and response
E.g. small forest patches cf. entire watersheds
2. Time scale of response
We assume “rapid” (sic) responses (1-2 yr) indicate
resilient behavior, whereas slower response times
(>100 yr) do not – is this true?
3. Level of biological organization (IPSCE)
We associate “resilient” behavior with getting back
the same species; alternative metastable states are
judged “novel” or type-converted
Case 1: Rapid, small scale disruption, rapid
recovery, individuals survive (“resilient”)
4
3
2
1
0
1
1
10
10
100
100
1000
BIOLOGICAL LEVEL
5
Landscape reburns in the
Chiricahua
Mountains, a
Madrean “Sky
Island”
Nested sequences
of fire severity
(U,L,M,H) in 2
events
Chiricahua maps and images:
Jesse Minor, U.Arizona
Pre-fire
Fuel models,
Chiricahua
Mountains
Figures courtesy
C. Stetson,
Coronado NF
and D.
Helmbrecht,
USFS TEAMS
Post-fire
Fuel models,
Chiricahua
Mountains
Figures courtesy
C. Stetson,
Coronado NF
and D.
Helmbrecht,
USFS TEAMS
Catalina Mts, 2013 (Photo: Jim
Malusa)
Catalina Mts, 1912 (Photo:
Forrest Shreve)
Case 2: Larger scale disruption, decadal
recovery, some turnover in species
1
1
10
10
100
100
1000
Near-total overstory tree mortality at watershed scale, 2011 Las Conchas Fire, Jemez
Mountains, NM
Following mortality events, species persistence is dependent on
recruitment, but climate trajectories may preclude conditions
Max growing season temp
Persistence
E1
E0
R
Min growing season soil water potential
Colwell and Rangel 2009
Case 3: Large scale disruption, multi-decadal
response, change in community (type conversion)
5
4
3
2
1
0
1
1
10
10
100
100
1000
Brock and Carpenter 2010; Scheffer et al. 2012
Conclusions
1.Resilience can be decomposed into
component scales and biological levels.
2.Post-disturbance ecological trajectories are
contingent on climate space, landscape
structure, soils, and disturbance regimes.
3.Restoration is a means of expanding the
resilience space in which ecosystems recover
in rapidly changing environments.
Post-fire aspen patches, Sangre de Cristo Mountains, NM: Ellis Margolis, University of Arizona
Thanks:
Craig Allen, USGS
Cal Farris, NPS
Rachel Loehman, Connie Millar, Don McKenzie, USFS
Research
Lauren Maghran, Ellis Margolis, Jim Malusa, Jesse Minor,
Tom Swetnam, University of Arizona
Bob Parmenter, Valles Caldera National Preserve
Chris Stetson, Craig Wilcox, Coronado National Forest
Andrea Thode, Northern Arizona University