Alpine Treeline Warming Experiment: "
Effects of microclimate on subalpine seedling establishment
within and beyond two species’ current elevation ranges Help!
Is this lovely?
1,2
Lara
M.
Kueppers
Cristina Castanha1,2, Andrew Moyes1 , Matt Germino3, Margaret Torn2,4,
John Harte4, Jeffry Mitton5 1UC Merced, 2LBNL, 3USGS, 4UC Berkeley, 5Univ of Colorado Climate envelope models "
used to project geographic shifts in species-associated climates at the
regional scale
Picea engelmannii
2030
2060
2090
(Rehfeldt et al., 2006)
Can species establish in newly suitable habitat?
Will species resist climate change in their current habitat?
Recruitment a bottleneck "
for both migration and persistence
Recruitment
1)  Will warming enable subalpine tree recruitment into current alpine
habitat?
2)  Will subalpine tree recruitment be impaired in the current subalpine
range with warming?
3)  Will climate-induced changes in subalpine tree recruitment be
modulated by genetic variation, ecophysiology or biogeochemistry?
Alpine treeline warming experiment"
warming x watering at three sites
USA
rodent exclosures
ALP
Alpine, Upper treeline, Lower subalpine forest
Experimental treatments
•  Heating: Infrared heaters with constant output
•  Watering: manual application 2.5 mm per week
•  Heating + Watering: ~compensate for drying (2.5 mm)
LSA Common gardens for three species
Alpine
Treeline
Forest
Soil temperature
Treatments shift microclimates for"
recruitment
+
-
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Soil moisture
Does warming increase recruitment
in the alpine? Possibly no.
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Alpine warming
•  Limber pine and Engelmann spruce can emerge and survive
under present conditions – stronger in a late snowmelt year
•  Warming tends to reduce emergence (only significant for
spruce in 2011)
•  Water availability may be more critical to spruce survival than
temperature (increase with water only significant in 2011).
•  Only spruce survivors to end of 2nd year in watered plots
Does warming impair recruitment in
current treeline? Maybe not. !#'"
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Treeline warming
•  Limber pine and Engelmann emergence and survival stronger
in a late snowmelt year
•  Warming effects inconsistent and perhaps more evident in
earlier snowmelt years •  Water availability not a strong constraint here
•  Latest snowmelt, seedlings avoid much of the June dry
period BUT only 2nd year spruce are in watered plots
Does warming impair recruitment in
current subalpine? Yes, at low edge
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Lower subalpine forest warming
•  Limber pine and Engelmann emergence and survival stronger
in a late snowmelt year
•  Warming depressed emergence and especially survival for
both species.
•  Water availability may be a key factor...
Limber pine physiological constraints
under low soil moisture
•  gs reduced at -1.5 MPas zero at -4 Mpa •  I.e., 5-10cm soil moisture ~0.16 m3 m-3 & ~0.08 m3 m-3
Time spent below these thresholds could impact carbon gain via
photosynthesis, and possibly survival
Seedlings have little stored carbon to draw on for growth or
maintenance when stomata are closed
(Moyes et al. in press Oecologia)
Survival correlated with GDD and
# days θ< 0.08 m3 m-3"
heated plots tend to be warmer and drier
Limber pine, low elevation provenance
H, HW
C, W
Alpine
Treeline
Forest
(Moyes et al. in press Oecologia)
Seasonal soil microclimate "
daily plot mean 5-10cm soil temperature and moisture
Forest (Moyes et al. in press Oecologia)
Treeline
Alpine
Summary and conclusions
•  Alpine suitable for limber pine now – but perhaps too dry for
Engelmann spruce
•  Warming may not increase recruitment
•  Warming may be detrimental to recruitment at treeline –or
perhaps inconsequential
•  In lower subalpine forest, warming to reduce recruitment,
perhaps due to acute and chronic moisture limitation
•  (Low elevation provenance emergence and survival is nearly
always greater than High at all sites – we also see
physiological differences between these pops…) Thank you!
DOE Office of Science, Terrestrial Ecosystem Science
Univ of Colo, Mountain Research Station and Niwot Ridge
LTER
B. Kimball (USDA), D. S. Christianson (UCB), J. Norris
(UCM), M. McLaughlin (USFS CDA Nursery), and A.
Schoettle (USFS)
Scott Ferrenberg, Ethan Brown and numerous fantastic
field technicians
https://alpine.ucmerced.edu/pub/htdocs/index.html