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| Titel |
The role of climate and hydrogeomorphic disturbance on riverine forest dynamics and landscape pattern in the Carmanah Valley temperate rainforest of coastal British Columbia, Canada. |
| VerfasserIn |
Patrick Little, John Richardson, Younes Alila |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250045491
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| Zusammenfassung |
| Riparian communities are among the most diverse, productive, and spatially heterogeneous
ecosystems in the landscape. Within the river corridor a mosaic of vegetation patches grows
on a variety of fluvial landforms. This heterogeneity can be attributed to the range of
hydrogeomorphic disturbance processes that operate on near stream vegetation. The
development and succession of floodplain forests is highly linked to processes of landscape
evolution which, in a pluvial hydroclimate, are ultimately controlled by climate events and
resulting floods. The aim of this study is to examine how the composition and structure of
riparian vegetation is controlled by hydrogeomorphic disturbance regimes and to assess how
increased storm frequencies, as predicted by climate change models, may affect riverine
forests.
The riverine landscape of the Carmanah Creek watershed on the west coast of Vancouver
Island, British Columbia, Canada was examined to reveal how channel migration and the
historic and contemporary hydroclimate perpetuate the shifting-mosaic of habitat types seen
within this relatively small area. The Carmanah watershed is a 67 km2 temperate
rainforest catchment whose half kilometer wide valley bottom is home to the tallest
trees (Picea sitchensis) in Canada. Thirty-eight plots containing 4509 trees were
sampled for forest structure, composition, age, understory composition, substrate
characteristics, and elevation above the contemporary channel. These field data,
including a vegetation chronosequence spanning over 500 years, were used to refine a
conceptual model that describes forest dynamics in relation to contemporary and
historic river channel position. Relationships between flood frequency and understory
as well as canopy species are also examined. This model quantifies successional
processes in relation to the unrelenting piecewise geomorphic reworking of the
valley bottom. Comparisons with riverine systems of contrasting hydroclimate and
basin area reveal visible signatures in riparian species composition and landscape
pattern.
Field based research is complemented by a landscape scale, multi-decadal analysis which
examines changes in the extent of specific habitat types using an aerial photographic
record spanning 70 years. Landscape change was correlated with hydrologic and
precipitation records in order to examine the relationship between hydroclimate and
landscape scale vegetation composition. Correlations between periods of heightened
disturbance and global climate cycles such as the El Nino Southern Oscillation are
also examined. This study supports predictions of the effects of climate change on
landscape patterns in riverine forests in this and other Pacific coastal watersheds. |
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