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ig. 5. Earth flow- and slide-derived gullies (1) and deposits (2) on a fluvial terrace (3) alter the soil and topography in the Peace River valley west of ort St. John.

Figure 5 ig. 5. Earth flow- and slide-derived gullies (1) and deposits (2) on a fluvial terrace (3) alter the soil and topography in the Peace River valley west of ort St. John.

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This paper provides 1) a perspective on the role landslides play in biophysical diversity, based on our field observations in British Columbia (BC) (Fig. 1); and 2) a selective review of the global literature. We hope that this paper will help stimulate further and more systematic studies of the influence of landslides on BC was almost entirely covered with ice during the last major (Wisconsinan) glaciation. The Cordilleran Ice Fig. 1. Map of British Columbia — note the geographic locations of other figures in the text.
This paper provides 1) a perspective on the role landslides play in biophysical diversity, based on our field observations in British Columbia (BC) (Fig. 1); and 2) a selective review of the global literature. We hope that this paper will help stimulate further and more systematic studies of the influence of landslides on BC was almost entirely covered with ice during the last major (Wisconsinan) glaciation. The Cordilleran Ice Fig. 1. Map of British Columbia — note the geographic locations of other figures in the text.
Fig. 2. Hummocks and ridges are common in flows such as this one at Buckinghorse River in northeastern BC.
Fig. 2. Hummocks and ridges are common in flows such as this one at Buckinghorse River in northeastern BC.
Fig. 3. Peat-filled sag pond (1) and sagebrush-covered ridge illustrating very wet and dry site conditions, at a landslide west of Williams Lake. in vegetation, contribute to increased habitat diversity, which is expressed at the landscape scale. Note that we are talking about biophysical not species diversity. Our three forms of diversity have some parallels to the alpha (within habitat), beta (between habitats), gamma (regional) hierarchy of species diversity (as presented in most standard ecology texts, e.g., Ricklefs, 2001). The three forms of biophysical diversity relate to or such diversity. We recognize biophysical diversity at three levels: site, soil, and habitat (ecosystem) diversity. Landslides usually change the site conditions at a given location, for example, making conditions drier or wetter, or stonier or muddier, more pervious or less pervious, sunnier, more exposed, etc. Changes to site conditions then also lead to changes in soils developing on those sites. Changes to site and soil, and the resultant changes
Fig. 3. Peat-filled sag pond (1) and sagebrush-covered ridge illustrating very wet and dry site conditions, at a landslide west of Williams Lake. in vegetation, contribute to increased habitat diversity, which is expressed at the landscape scale. Note that we are talking about biophysical not species diversity. Our three forms of diversity have some parallels to the alpha (within habitat), beta (between habitats), gamma (regional) hierarchy of species diversity (as presented in most standard ecology texts, e.g., Ricklefs, 2001). The three forms of biophysical diversity relate to or such diversity. We recognize biophysical diversity at three levels: site, soil, and habitat (ecosystem) diversity. Landslides usually change the site conditions at a given location, for example, making conditions drier or wetter, or stonier or muddier, more pervious or less pervious, sunnier, more exposed, etc. Changes to site conditions then also lead to changes in soils developing on those sites. Changes to site and soil, and the resultant changes
Fig. 4. Numerous ponds occur in the ridged topography of the Muskwa earth flow in northeastern BC. The landslide dammed a stream, resulting in the pond at the extreme right. Landslides change soil properties primarily by exposing parent material (the C horizon), or in some cases removing organic mats and A horizons. This can result in a mosaic of stages of soil development in a andscape unit (Huggett, 1998). Ata given site, a Podzol soil names according to the Canadian System of Soil Classification (Soil Classification Working Group, 998)) may be removed, exposing a regosol, thus resetting the pedogenic clock to the initial stages of a Regosol — Brunisol — Podzol sequence. Smith et al. (1986) found that debris slides on the Queen Charlotte slands produced a mixture of regosols, and perturbated —
Fig. 4. Numerous ponds occur in the ridged topography of the Muskwa earth flow in northeastern BC. The landslide dammed a stream, resulting in the pond at the extreme right. Landslides change soil properties primarily by exposing parent material (the C horizon), or in some cases removing organic mats and A horizons. This can result in a mosaic of stages of soil development in a andscape unit (Huggett, 1998). Ata given site, a Podzol soil names according to the Canadian System of Soil Classification (Soil Classification Working Group, 998)) may be removed, exposing a regosol, thus resetting the pedogenic clock to the initial stages of a Regosol — Brunisol — Podzol sequence. Smith et al. (1986) found that debris slides on the Queen Charlotte slands produced a mixture of regosols, and perturbated —
Fig. 6. The Mink Creek earth flow-spread near Terrace BC. Note the gray-ridged microtopography, translated pre-slide trees and vegetation mats, as well as acidic brown Podzolic surface soil. The pH of the unweathered gray soil is around 8.
Fig. 6. The Mink Creek earth flow-spread near Terrace BC. Note the gray-ridged microtopography, translated pre-slide trees and vegetation mats, as well as acidic brown Podzolic surface soil. The pH of the unweathered gray soil is around 8.
Fig. 7. Alder-covered debris slides (1) on the west coast of the Queen Charlotte Islands. Photo courtesy J.W. Schwab.
Fig. 7. Alder-covered debris slides (1) on the west coast of the Queen Charlotte Islands. Photo courtesy J.W. Schwab.
Fig. 8. A large rock slide (a) south of Chisca River, covered hummocky black spruce forest (b) and has been colonized by willows (c), heavily utilizes by moose.
Fig. 8. A large rock slide (a) south of Chisca River, covered hummocky black spruce forest (b) and has been colonized by willows (c), heavily utilizes by moose.
Fig. 9. Beavers often opportunistically utilize ridged terrain in landslides, creating pond habitat or damming (1) the outlets of existing ponds. (e.g. Fig. 7). They distinguished 8 vegetation groups on 49 landslides. The differences were primarily attributed to age and position on the landslide. As time since failure increased, both species composition and percent cover changed. For example, the earliest colonizers tended to be shrubs and ferns (1—11% cover), later followed by young trees — red alder, western hemlock and Sitka spruce (more than 16% cover). The deciduous red alder dominated the stands for about 5 decades, but then began to decline under the hegemony of evergreen conifers. As the alder disappeared, Sitka spruce rose to dominate the stands. The upper rubble-covered, or bedrock-exposed slopes typically were not colonized by red alder — there western hemlock and Sitka spruce occupied the landslides. The assemblage of shrubs and herbs on the landslides was different from that in the surrounding forest.
Fig. 9. Beavers often opportunistically utilize ridged terrain in landslides, creating pond habitat or damming (1) the outlets of existing ponds. (e.g. Fig. 7). They distinguished 8 vegetation groups on 49 landslides. The differences were primarily attributed to age and position on the landslide. As time since failure increased, both species composition and percent cover changed. For example, the earliest colonizers tended to be shrubs and ferns (1—11% cover), later followed by young trees — red alder, western hemlock and Sitka spruce (more than 16% cover). The deciduous red alder dominated the stands for about 5 decades, but then began to decline under the hegemony of evergreen conifers. As the alder disappeared, Sitka spruce rose to dominate the stands. The upper rubble-covered, or bedrock-exposed slopes typically were not colonized by red alder — there western hemlock and Sitka spruce occupied the landslides. The assemblage of shrubs and herbs on the landslides was different from that in the surrounding forest.
Fig. 10. The landslide dam of the Muskwa earth flow (Fig. 4). Note the numerous standing (as well as down) dead trees. Such trees provide important perch and cavity nesting habitat. In forested landscapes in BC, we have generally observed a distinct vegetative difference between land- slides and the surrounding forest. For example in the Chisca River area of northern BC, a rock avalanche spread over black spruce muskeg; willow and birch
Fig. 10. The landslide dam of the Muskwa earth flow (Fig. 4). Note the numerous standing (as well as down) dead trees. Such trees provide important perch and cavity nesting habitat. In forested landscapes in BC, we have generally observed a distinct vegetative difference between land- slides and the surrounding forest. For example in the Chisca River area of northern BC, a rock avalanche spread over black spruce muskeg; willow and birch
Fig. 11. These sandstone slopes in northeastern BC have been subject to rotational failure and rock fall. Note the cliff habitat (1), rubble aprons (2) and beaver-dammed sag ponds (3) — all creating a biophysical diversity.
Fig. 11. These sandstone slopes in northeastern BC have been subject to rotational failure and rock fall. Note the cliff habitat (1), rubble aprons (2) and beaver-dammed sag ponds (3) — all creating a biophysical diversity.
Fig. 12. The Inklin River upstream of a landslide dam. Note the lack of conifers and the presence deciduous shrubs in the previously submerged zone. shrubs have replaced the original forest (Fig. 8). The larger, low gradient earth flows tend to create very complex microtopographies, resulting in a wide range of moisture regimes. A corresponding spectrum of vege- tation occupies the microhabitats in response to the variable site characteristics. Aquatic vegetation forms in ponds — often eventually passing on to peatland communities. Dry-site lichens may cover rubble and gravelly ridges in landslides. Such differences can Large earth flows or slides with hummocky or ridged microtopography often form ponds or water-charged templates for wetland development (e.g., “breaks” of
Fig. 12. The Inklin River upstream of a landslide dam. Note the lack of conifers and the presence deciduous shrubs in the previously submerged zone. shrubs have replaced the original forest (Fig. 8). The larger, low gradient earth flows tend to create very complex microtopographies, resulting in a wide range of moisture regimes. A corresponding spectrum of vege- tation occupies the microhabitats in response to the variable site characteristics. Aquatic vegetation forms in ponds — often eventually passing on to peatland communities. Dry-site lichens may cover rubble and gravelly ridges in landslides. Such differences can Large earth flows or slides with hummocky or ridged microtopography often form ponds or water-charged templates for wetland development (e.g., “breaks” of
Related topics:
GeologyGeomorphologySnow and Avalanche ResearchAquatic EcosystemBoreal ForestEcological SuccessionSurface Texture
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