Holocene precipitation in the coastal temperate rainforest complex of southern British Columbia, Canada

Brown, Kendrick J.; Fitton, R. J.; Schoups, Gerrit; Allen, Gregory B.; Wahl, Kimberly; Hebda, Richard J.

doi:10.1016/j.quascirev.2006.02.020

Cited by 33 publications

(38 citation statements)

References 45 publications

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“…However, changes in vegetation and fire activity were not synchronous except at the late-glacial/early-Holocene transition at 11 700 cal yr BP, when warm-climate xerophytic species replaced cold-climate mesophytic species and fire activity became more frequent on all substrates. The asynchrony of change at other times may be explained by (1) bottom-up controls (i.e., topography) that alter the effects of large-scale climate changes (e.g., Gavin et al 2006 changes in the location of climate boundaries (e.g., Heinrichs et al 2002, Briles et al 2005, Brown et al 2006, Huerta et al 2009), and (3) edaphic conditions (e.g., Brubaker 1975, Millspaugh et al 2000; see Results and discussion) that lead to disparities in vegetation sensitivity to large-scale change. This asynchrony suggests that relationships beyond direct impacts of climate on vegetation and fire regimes should be considered in the development of management and conservation plans.…”

Section: Resultsmentioning

confidence: 99%

Holocene forest development and maintenance on different substrates in the Klamath Mountains, northern California, USA

Briles

Whitlock

Skinner

et al. 2011

Ecology

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The influence of substrate on long-term vegetation dynamics has received little attention, and yet nutrient-limited ecosystems have some of the highest levels of endemism in the world. The diverse geology of the Klamath Mountains of northern California (USA) allows examination of the long-term influence of edaphic constraints in subalpine forests through a comparison of vegetation histories between nutrient-limited ultramafic substrates and terrain that is more fertile. Pollen and charcoal records spanning up to 15000 years from ultramafic settings reveal a distinctly different vegetation history compared to other soil types. In non-ultramafic settings, the dominant trees and shrubs shifted in elevation in response to Holocene climate variations resulting in compositional and structural changes, whereas on ultramafic substrates changes were primarily structural, not compositional. Fire activity was similar through most of the Holocene with the exception of declines over the last 4000 years on ultramafic substrates, likely due to the reduction of understory fuels and cooler wetter conditions than in the middle Holocene. These results suggest that the tree and shrub distributions were more responsive to past climate changes on non-ultramafic substrates compared to those on ultramafic substrates. The combination of these dynamics may help explain high levels of plant diversity in the Klamath Mountains and provide insights for managing these complex ecosystems.

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Section: Resultsmentioning

confidence: 99%

Holocene forest development and maintenance on different substrates in the Klamath Mountains, northern California, USA

Briles

Whitlock

Skinner

et al. 2011

Ecology

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“…Changes in Holocene precipitation were estimated from stratigraphic pollen data in lake sediment cores, following the analysis of Brown et al (2006), who developed a pollen-precipitation transfer function using both lake surface sediments and litter samples. The original transfer function did not account for how changes in elevation influenced the distribution of precipitation.…”

Section: Precipitationmentioning

confidence: 99%

Multi-millennial streamflow dynamics in two forested watersheds on Vancouver Island, Canada

Brown

Schoups

2015

Quat. res.

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a b s t r a c tHolocene streamflow was reconstructed for two rivers on Vancouver Island, British Columbia, Canada in 500-yr intervals. The San Juan River watershed is located on the wetter western side of the island, whereas the Koksilah River watershed is positioned on the drier eastern side. Both watersheds are forested. To reconstruct streamflow, temporal changes in precipitation (estimated using a pollen-based transfer function) and evapotranspiration were established for each watershed and integrated into a water balance model, calibrated using modern data. While seasonal streamflow variability was maintained throughout the Holocene, with greater flow in the winter relative to the summer, the amount of discharge has changed markedly through time. Lowest simulated flow occurred in the earliest Holocene, with low-flow conditions beginning earlier in the year and extending later into the fall. Such conditions may have inhibited salmon from using many of the smaller rivers in the region. Streamflow steadily increased throughout the early Holocene so that by ca. 6500 cal yr before present nearmodern flow regimes were established. As climate changes in the future, the San Juan and Koksilah watersheds are expected to remain as pluvial hydroclimatic regimes, though with an extended season of low flow similar to conditions during the early Holocene.Crown

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“…The Holocene climate for Vancouver Island has been established using vegetation records and climate transfer functions (Figure 3, Alley & Chatwin 1979;Brown et al 2006;Brown & Hebda 2002a;Carlson 1979;Hay et al 2007;Hebda 1983;Hebda & Rouse 1979). Brown et al (2006) used a vegetative index that compared the proportional distribution of coastal Douglas-fir and coastal western hemlock to quantify temporal changes in Holocene precipitation for the southern part of Vancouver Island. The results yielded precipitation isopleths in 1000 year intervals for the Holocene and showed that overall, temporal changes in precipitation were generally subtle, though a notable increase in precipitation is observed at the end of the Holocene dry period.…”

Section: Determining Holocene Landslide Ratesmentioning

confidence: 99%

“…Overwhelming evidence reveals that Vancouver Island was ice free, vegetated and dry by 11,700 calendar years before present (y BP), following a rapid rise in temperature (Alley & Chatwin 1979;Brown et al 2006;Carlson 1979;Hay et al 2007;Hebda 1983). Following the warm-dry xerothermic interval (11,700-7,000 y BP), an increase in precipitation coincides with the start of the wetter mesothermic interval (7,000-4,000 y BP).…”

Section: Introductionmentioning

confidence: 99%

Denudation and landslides in coastal mountain watersheds : 10,000 years of erosion

Guthrie

Brown

2008

Geogr. Helv.

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Abstract. A conceptual model of landslide-induced denudation for coastal mountain watersheds spanning 10,000 years of environmental change is presented. The model uses a constructed paleo-climate based on vegetation records and an established relationship between landslide frequencies and precipitation. Landslide frequencies are determined for the early warm dry Holocene, the warm wet middle Holocene and modern climates. Average landslide rates vary between 0.005 landslides·y-1·km-2 and 0.008 landslides·y-1·km-2. Recent human impacts are calculated by recalculating landslide frequencies for logged areas in the 20th century. The impact of logging during the last 100 years is unambiguous as landslide frequency increased to 0.015 landslides·y-1·km-2. This suggests that the impact of logging outpaces that of climatic change. It is estimated that debris slides and flows eroded an average of 0.7 m·m-2 across Vancouver Island during the last 10,000 years.

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Holocene precipitation in the coastal temperate rainforest complex of southern British Columbia, Canada

Cited by 33 publications

References 45 publications

Holocene forest development and maintenance on different substrates in the Klamath Mountains, northern California, USA

Holocene forest development and maintenance on different substrates in the Klamath Mountains, northern California, USA

Multi-millennial streamflow dynamics in two forested watersheds on Vancouver Island, Canada

Denudation and landslides in coastal mountain watersheds : 10,000 years of erosion

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