TY - JOUR
T1 - Differential declines in Alaskan boreal forest vitality related to climate and competition
AU - Trugman, Anna T.
AU - Medvigy, David
AU - Anderegg, William R.L.
AU - Pacala, Stephen Wilson
N1 - Funding Information:
The authors gratefully acknowledge support from the Princeton Environmental Institute Walbridge Fund and the National Science Foundation Graduate Research Fellowship (to A.T.T.) and the NSF DEB Grants EF-1340270 and 1714972 (to W.R.L.A.) and thank Thomas Malone of the Cooperative Alaska Forest Inventory for his help providing plot inventory and site age data.
Funding Information:
Princeton Environmental Institute Walbridge Fund; National Science Foundation Graduate Research Fellowship; NSF DEB, Grant/ Award Number: EF-1340270, 1714972
Publisher Copyright:
© 2017 John Wiley & Sons Ltd
PY - 2018/3
Y1 - 2018/3
N2 - Rapid warming and changes in water availability at high latitudes alter resource abundance, tree competition, and disturbance regimes. While these changes are expected to disrupt the functioning of boreal forests, their ultimate implications for forest composition are uncertain. In particular, recent site-level studies of the Alaskan boreal forest have reported both increases and decreases in productivity over the past few decades. Here, we test the idea that variations in Alaskan forest growth and mortality rates are contingent on species composition. Using forest inventory measurements and climate data from plots located throughout interior and south-central Alaska, we show significant growth and mortality responses associated with competition, midsummer vapor pressure deficit, and increased growing season length. The governing climate and competition processes differed substantially across species. Surprisingly, the most dramatic climate response occurred in the drought tolerant angiosperm species, trembling aspen, and linked high midsummer vapor pressure deficits to decreased growth and increased insect-related mortality. Given that species composition in the Alaskan and western Canadian boreal forests is projected to shift toward early-successional angiosperm species due to fire regime, these results underscore the potential for a reduction in boreal productivity stemming from increases in midsummer evaporative demand.
AB - Rapid warming and changes in water availability at high latitudes alter resource abundance, tree competition, and disturbance regimes. While these changes are expected to disrupt the functioning of boreal forests, their ultimate implications for forest composition are uncertain. In particular, recent site-level studies of the Alaskan boreal forest have reported both increases and decreases in productivity over the past few decades. Here, we test the idea that variations in Alaskan forest growth and mortality rates are contingent on species composition. Using forest inventory measurements and climate data from plots located throughout interior and south-central Alaska, we show significant growth and mortality responses associated with competition, midsummer vapor pressure deficit, and increased growing season length. The governing climate and competition processes differed substantially across species. Surprisingly, the most dramatic climate response occurred in the drought tolerant angiosperm species, trembling aspen, and linked high midsummer vapor pressure deficits to decreased growth and increased insect-related mortality. Given that species composition in the Alaskan and western Canadian boreal forests is projected to shift toward early-successional angiosperm species due to fire regime, these results underscore the potential for a reduction in boreal productivity stemming from increases in midsummer evaporative demand.
KW - Alaska
KW - boreal forest
KW - climate change
KW - drought
KW - forest inventory
KW - growth decline
KW - insect-induced mortality
KW - terrestrial carbon cycle
KW - vapor pressure deficit
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U2 - 10.1111/gcb.13952
DO - 10.1111/gcb.13952
M3 - Article
C2 - 29055122
AN - SCOPUS:85042161103
SN - 1354-1013
VL - 24
SP - 1097
EP - 1107
JO - Global Change Biology
JF - Global Change Biology
IS - 3
ER -