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The recent effects of Dothistroma septospora on forest health and tree mortality has underscored the need to establish a causal relationship between forest health impacts (Dothistroma) and climate forcing events (El Nino/ La Nina, PDO). Woods et al. (2005) has shown Dothistroma to be related to climate change and further work by the University of Northern BC agrees with Woods et al., suggesting that Dothistroma responds sensitively to temperature and precipitation patterns. However, before we can establish strategies to reduce future risks we first need to develop a cause and effect relationship. Understanding paleoclimate is a necessary process in reconstructing ecosystem responses to current climate forcing events; and eventually predicting ecosystem structure. Therefore in order to improve our understanding of inter-decadal to inter-annual-scale climate variability we need to extend our observation beyond the instrument record (Jacoby and D?Arrigo 1999).
Annually resolved tree-ring analysis is a widely accepted proxyindicator of climate variability. Providing baseline information on the spatial extend and natural variability of regional climate (Wiles et al. 1998). Instrumental records of paleoclimate offer significant evidence that the Northeast Pacific experiences distinct modes of climate variability (Ware 1995; Mantua et al. 1997; Zhang et al. 1997), with decadal-scale variability dominated by the Northern Oscillation Index (NOI) (Schwing et al. 2002) and the Pacific Decadal Oscillation (PDO) (Hare and Mantua 2000; Gedalof and Smith 2001, Gedalof et al. 2002;). Inter-decadal and inter-annual variability also tend to be strongly influenced by El Niņo / Southern Oscillation (ENSO), which exhibits a spatial organization similar to that of the PDO (Gedalof 2002). Climate of the Northeast Pacific is further influenced by the Aleutian Low pressure cell during winter and spring months (Wiles et al. 1998). Recent multiproxy research suggests the frequency and magnitude of these processes are increasingly variable due to climate forcing processes such as PDO, ENSO, NOI, Pacific North American Pattern (PNA) and the Aleutian Low Pressure Index (APLI) (Gedalof 2002). Attendant to these processes are an increase in local climatic anomalies and extreme weather patterns emanating distinct ecosystem responses in the Pacific Northwest (Cayan et al. 1998, Mantua and Hare 2002).
This proposal describes an approach to reconstruct paleoclimate, using tree ring analysis, in the Skeena Stikine Forest District to relate climate forcing events to Dothistroma outbreaks. This work is aimed at deepening our understanding as to the effects of climate variability in this region. This project will use tree ring analysis to further build on recent work by Woods et al. (2005) and UNBC. Dendroclimatology has two distinct advantages over other proxy indicators of paleoclimate. First, a living tree-ring chronology provides exact annual resolution. Second, the technique refines confidence by defining variability of measurement separately from the climate signal. Developing such paleoproxy indicators in the Skeena Stikine Forest District will aid to interpret recent forest health impacts (temperature and precipitation anomalies) and subsequent ecosystem responses (Dothistroma), while placing these changes in the context of longer-term climate (Davi et al. 2003). Three high-elevation sites will be established to compliment work done by the UVic Tree Ring Laboratory. The sub-alpine Mountain Hemlock Zone has been chosen as Mountain Hemlock (Tsuga mertensiana) and White Spruce (Picea glauca) trees respond sensitively to climate and store coherent signals of low-frequency climate forcing processes within their radial growth (Smith and Laroque 1998). One hundred and twenty cores from 60 T.mertensiana and P. glauca will be collected, processed and analyzed to create a ring-width index from which a climate signal will be extracted. Spatial autocorrelations ...
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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