A 6000‐Year Record of Forest History on Mount Rainier, Washington

Dunwiddie, Peter W.

doi:10.2307/1938503

Cited by 41 publications

(24 citation statements)

References 20 publications

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“…Plant macrofossils in sediments of small lakes generally represent trees growing within 10 0 -10 1 meters of the lake margin [17,58]. Such spatial precision has considerable advantages in application, but it also ensures that only a small number of individual trees are likely to be represented in a macrofossil assemblage.…”

Section: Discussionmentioning

confidence: 99%

Ancient DNA from lake sediments: Bridging the gap between paleoecology and genetics

et al. 2011

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BackgroundQuaternary plant ecology in much of the world has historically relied on morphological identification of macro- and microfossils from sediments of small freshwater lakes. Here, we report new protocols that reliably yield DNA sequence data from Holocene plant macrofossils and bulk lake sediment used to infer ecological change. This will allow changes in census populations, estimated from fossils and associated sediment, to be directly associated with population genetic changes.ResultsWe successfully sequenced DNA from 64 samples (out of 126) comprised of bulk sediment and seeds, leaf fragments, budscales, and samaras extracted from Holocene lake sediments in the western Great Lakes region of North America. Overall, DNA yields were low. However, we were able to reliably amplify samples with as few as 10 copies of a short cpDNA fragment with little detectable PCR inhibition. Our success rate was highest for sediments < 2000 years old, but we were able to successfully amplify DNA from samples up to 4600 years old. DNA sequences matched the taxonomic identity of the macrofossil from which they were extracted 79% of the time. Exceptions suggest that DNA molecules from surrounding nearby sediments may permeate or adhere to macrofossils in sediments.ConclusionsAn ability to extract ancient DNA from Holocene sediments potentially allows exciting new insights into the genetic consequences of long-term environmental change. The low DNA copy numbers we found in fossil material and the discovery of multiple sequence variants from single macrofossil extractions highlight the need for careful experimental and laboratory protocols. Further application of these protocols should lead to better understanding of the ecological and evolutionary consequences of environmental change.

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Section: Discussionmentioning

confidence: 99%

Ancient DNA from lake sediments: Bridging the gap between paleoecology and genetics

et al. 2011

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“…On Mt. Rainier, for example, Dunwiddie (1986) demonstrated that fires that occurred during the mid-1800s burned through an Abies amabilis and Tsuga mertensiana forest that had persisted for centuries. The mid-1800s were characterized by warming temperatures that caused earlier seasonal snowmelt and longer growing seasons.…”

Section: Crown Fire Dynamics In a Changing Climatementioning

confidence: 99%

“…These climate conditions allowed Tsuga heterophylla to become abundant briefly after the fires, and T. heterophylla was then replaced by A bies lasiocarpa. Because long-lived mature trees may survive short-term climate fluctuations, species that are best adapted to the current climate may only be able to enter the forest in open habitats following severe fires, and forest composition may respond to climatic changes primarily after disturbance (Dunwiddie 1986). A study by Cwynar (1987) also suggests that, although the ultimate cause of postglacial vegetation change in the Pacific Northwest was climate change, the proximate cause of some postglacial vegetation changes was an altered fire regime.…”

Section: Crown Fire Dynamics In a Changing Climatementioning

confidence: 99%

Landscape dynamics in crown fire ecosystems

1994

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Crown fires create broad-scale patterns in vegetation by producing a patch mosaic of stand age classes, but the spread and behavior of crown fires also may be constrained by spatial patterns in terrain and fuels across the landscape. In this review, we address the implications of landscape heterogeneity for crown fire behavior and the ecological effects of crown fires over large areas. We suggest that fine-scale mechanisms of fire spread can be extrapolated to make broad-scale predictions of landscape pattern by coupling the knowledge obtained from mechanistic and empirical fire behavior models with spatially-explicit probabilistic models of fire spread. Climatic conditions exert a dominant control over crown fire behavior and spread, but topographic and physiographic features in the landscape and the spatial arrangement and types of fuels have a strong influence on fire spread, especially when burning conditions (e.g., fuel moisture and wind) are not extreme.General trends in crown fire regimes and stand age class distributions can be observed across continental, latitudinal, and elevational gradients. Crown fires are more frequent in regions having more frequent and/or severe droughts, and younger stands tend to dominate these landscapes. Landscapes dominated by crown fires appear tobe nonequilibrium systems. This nonequilibrium condition presents a significant challenge to land managers, particularly when the implications of potential changes in the global climate are considered. Potential changes in the global climate may alter not only the frequency of crown fires but also their severity. Crown fires rarely consume the entire forest, and the spatial heterogeneity of burn severity patterns creates a wide range of local effects and is likely to influence plant reestablishment as well as many other ecological processes. Increased knowledge of ecological processes at regional scales and the effects of landscape pattern on fire dynamics should provide insight into our understanding of the behavior and consequences of crown fires.

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“…Empirical evidence was invoked by some other panelists to support the contrasting view, that succession after disturbance is unpredictable. One panelist drew on paleoecological evidence from Mount Rainier in the Pacific Northwest of the United States (Dunwiddie 1986) suggesting that climate change has altered the regeneration niche for tree species so that a disturbance event ''flipped'' the forest system to a completely new species assemblage.…”

Section: Nonlinear Development and Uncertaintymentioning

confidence: 99%