Growth responses of subalpine fir to climatic variability in the Pacific Northwest

Abstract

We studied regional variation in growth-limiting factors and responses to climatic variability in subalpine forests by analyzing growth patterns for 28 tree-ring growth chronologies from subalpine fir (Abies lasiocarpa (Hook.) Nutt.) stands in the Cascade and Olympic Mountains (Washington and Oregon, U.S.A.). Factor analysis identified four distinct time series of common growth patterns; the dominant growth pattern at any site varied with annual precipitation and temperature (elevation). Throughout much of the region, growth is negatively correlated with winter precipitation and spring snowpack depth, indicating that growth is limited primarily by short growing seasons. On the driest and warmest sites, growth is negatively correlated with previous summer temperature, suggesting that low summer soil moisture limits growth. Growth patterns in two regions were sensitive to climatic variability associated with the Pacific Decadal Oscillation, apparently responding to low-frequency variation in spring snowpack and summer soil moisture (one negatively, one positively). This regional-scale analysis shows that subalpine fir growth in the Cascades and Olympics is limited by different climatic factors in different subregional climates. Climate-growth relationships are similar to those for a co-occurring species, mountain hemlock (Tsuga mertensiana (Bong.) Carrière), suggesting broad biogeographic patterns of response to climatic variability and change by subalpine forest ecosystems in the Pacific Northwest.Résumé : Les auteurs ont étudié la variation régionale des facteurs qui limitent la croissance et les réponses à la variabilité climatique de forêts subalpines en analysant les patrons de croissance de 28 séries dendrochronologiques établies à partir de peuplements de sapin subalpin (Abies lasiocarpa (Hook.) Nutt.) situés dans les Cascades et les monts Olympic (Washington et Oregon, États-Unis). Une analyse factorielle a identifié quatre séries temporelles distinctes de patrons de croissance communs; le patron de croissance dominant dans tous les sites varie en fonction de la précipitation annuelle et de la température (altitude). Dans la plus grande partie de la région, la croissance est négativement corrélée à la précipitation hivernale et à la hauteur de neige accumulée au printemps, ce qui indique que la croissance est surtout limitée par de courtes saisons de croissance. Dans les sites les plus chauds et les plus secs, la croissance est néga-tivement corrélée à la température de l'été précédent, indiquant qu'une faible quantité d'humidité dans le sol en été limite la croissance. Les patrons de croissance de deux régions sont sensibles aux variations climatiques associées à l'Oscillation Décennale du Pacifique, en répondant apparemment à la variation de basse fréquence de la couverture nivale au printemps et de l'humidité du sol en été (négativement dans un cas et positivement dans l'autre). Cette analyse à l'échelle régionale montre que la croissance du sapin subalpin dans les Cascades et les monts Olympic est limit...

Climate-driven synchrony across tree, bivalve, and rockfish growth-increment chronologies of the northeast Pacific

“…For example, in southeast Alaska, tree-ring chronologies are positively associated with spring and summer land temperatures, which are positively associated with sea surface temperatures (Wiles et al 1998, D'Arrigo et al 1999, Gedalof & Smith 2001. In the Cascade Mountains and northern California, snowpack becomes an additional limiting variable, the depth and duration of which negatively correlate with winter and spring ocean temperatures (Gedalof & Smith 2001, Peterson et al 2002. Farther south, precipitation is positively associated with warm waters, and tree growth is most negatively impacted by drought, as would occur during La Niña events or negative phases of the PDO (Biondi et al 1999, Biondi et al 2001.…”

Nonlinear dynamics in ecosystem response to climatic change: Case studies and policy implications

“…The PDO is negatively correlated with winter precipitation (snow) (Peterson et al, 2002;Selkowitz et al, 2002) (Fig. 7), and snowpack dynamics are critical to glacier mass balance, with more rapid recession during the two warm PDO regimes of the 20th century (Bitz and Battisti, 1999;Key et al, 2002;J.…”

“…Growth of mountain hemlock (Tsuga mertensiana) ) and subalpine fir (Abies lasiocarpa) (Peterson et al, 2002) is positively correlated with PDO at treeline (where snowpack limits length of growing season) and negatively correlated with PDO at lower elevations (where soil moisture storage limits summer growth) in the Olympic and northern Cascade Mountains . Therefore, multidecadal climatic phenomena control growth and productivity of forest ecosystems at local and regional scales, and tree growth is somewhat predictable over a period of several decades.…”

Climate change effects on vegetation in the Pacific Northwest: a review and synthesis of the scientific literature and simulation model projections

“…(Knutson 2006, Kusnierczyk and, suggesting a strong water limitation on net primary production. In contrast, tree growth in subalpine forests can be negatively correlated with winter precipitation and spring snowpack depth and positively correlated with summer temperatures, suggesting that temperature and growing season length limit production Peterson 1994, 2001;Peterson et al 2002). Within the continuous forest zone, tree growth is often positively correlated with soil water availability to varying degrees (Case andPeterson 2005, 2007;Littell et al 2008;Nakawatase and Peterson 2006).…”