Postglacial spread of hemlock (Tsuga) and vegetation history in Mount Revelstoke National Park, British Columbia, Canada

2003 ◽  
Vol 81 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Sandra M Rosenberg ◽  
Ian R Walker ◽  
Rolf W Mathewes
Keyword(s):  
British Columbia ◽  
National Park ◽  
Late Holocene ◽  
Environmental Changes ◽  
Vegetation History ◽  
Climatic Conditions ◽  
Western Hemlock ◽  
Migration Route ◽  
Geological Evidence ◽  
Eagle Lake

To investigate postglacial environmental changes in southeastern British Columbia, subfossil pollen was analyzed from Eagle Lake, Mount Revelstoke National Park. Palynological evidence suggests that during the early Holocene, Eagle Lake was surrounded by an open forest. The pollen assemblage indicates that climatic conditions were warmer and drier than at present with high alder pollen values. Spruce and fir were common in local forests throughout the Holocene. Western hemlock pollen first occurs at approximately 3500 14C years BP. The migration path of western hemlock into this region is currently unclear. Data from palynological records appear insufficient to resolve the migration pattern, although several routes are possible. The available data support northward migration into southeastern British Columbia. The arrival of this conifer may be in response to the late Holocene increase in precipitation, as inferred from many lower elevation and coastal sites. Mountain hemlock pollen does not appear until about 2100 14C years BP. Mountain hemlock's migration route into southeastern British Columbia is also unresolved. In the late Holocene, the presence of mountain hemlock, and increases of Ericales and Valeriana sitchensis pollen, suggest a shift to the more open, cool, and moist conditions characteristic of the modern-day subalpine parkland. These climatic inferences correspond closely to those derived from other palynological and geological evidence throughout southern British Columbia.Key words: pollen, vegetation, Tsuga, hemlock, British Columbia, Holocene, climate.

Holocene vegetation history and fire regimes of Pseudotsuga menziesii forests in the Gulf Islands National Park Reserve, southwestern British Columbia, Canada

2013 ◽  
Vol 79 (3) ◽  
pp. 366-376 ◽  
Author(s):  
Jennifer D. Lucas ◽  
Terri Lacourse
Keyword(s):  
British Columbia ◽  
Pseudotsuga Menziesii ◽  
National Park ◽  
Prescribed Burning ◽  
Vegetation History ◽  
Fire Regimes ◽  
Ice Age ◽  
Pteridium Aquilinum ◽  
Quercus Garryana ◽  
Gulf Islands

AbstractPollen analysis of a 9.03-m-long lake sediment core from Pender Island on the south coast of British Columbia was used to reconstruct the island's vegetation history over the last 10,000 years. The early Holocene was characterized by open mixed woodlands with abundant Pseudotsuga menziesii and a diverse understory including Salix and Rosaceae shrubs and Pteridium aquilinum ferns. The establishment of Quercus garryana savanna-woodland with P. menziesii and Acer macrophyllum followed deposition of the Mazama tephra until ~ 5500 cal yr BP, when these communities gave way to modern mixed P. menziesii forest. Charcoal analyses of the uppermost sediments revealed low charcoal accumulation over the last 1300 years with a mean fire return interval (mFRI) of 88 years. Fires were more frequent (mFRI = 50 yr) during the Medieval Climate Anomaly (MCA) with warm, dry conditions facilitating a higher fire frequency than during the Little Ice Age, when fires were infrequent. Given the projected warming for the next 50–100 years, land managers considering the reintroduction of fire to the Gulf Islands National Park Reserve may want to consider using the mFRI of the MCA as a baseline reference in prescribed burning strategies.

scholarly journals Foraminiferal Evidence of Late Holocene Sea-Level Change and Amerindian Site Distribution at Montague Harbour, British Columbia

2007 ◽  
Vol 50 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Eduard G. Reinhardt ◽  
Norman A. Easton ◽  
R. Timothy Patterson
Keyword(s):  
British Columbia ◽  
Sea Level ◽  
Late Holocene ◽  
Environmental Changes ◽  
Tectonic Subsidence ◽  
Archaeological Remains ◽  
Sea Level Changes ◽  
Site Distribution ◽  
Low Salinity ◽  
Holocene Sea Level

ABSTRACT Foraminiferal and sedimentological analysis of an underwater stratigraphie section from an Amerindian habitation site at Montague Harbour, British Columbia has further documented late Holocene sea level changes. It appears that part of the documented transgression was caused by tectonic subsidence of the area (Event 1 at approx. 3500 calendar years BP and Event 2 sometime before 1100 calendar years BP) and was recognized in the stratigraphie record by rapid environmental changes. The environmental changes caused by rapid shifts in water depth were recognized through sedimentological and foraminiferal evidence. The tectonic subsidence events, coupled with gentle late Holocene transgression, caused the breaching of Montague Harbour's northwestern channel. The breaching of the channel improved water circulation and increased salinity within the harbour. The salinity changes are reflected in the shift from a low salinity Cribroelphidium excavatum (Terquem, 1876) phenotype "clavata" dominated biofacies (1) at the base of the section to a higher salinity Buccella tenerrima (Bandy, 1950) and Elphidiella hannai (Cushman and Grant, 1927) dominated biofacies (2) at the top. These sea-level changes would have eventually forced local Amerindian settlements inland. The 14C dating of wood and shell, indicates that the recovery of archaeological remains of the Charles culture (ca.6500-3200 years BP) requires investigation in deeper waters.

Decadal high-resolution multi-proxy analysis to reconstruct natural and human-induced environmental changes over the last 1350 cal. yr BP in the Altai Tavan Bogd National Park, western Mongolia

The Holocene ◽  
2020 ◽  
Vol 30 (7) ◽  
pp. 1016-1028 ◽  
Author(s):  
Julia Unkelbach ◽  
Kaoru Kashima ◽  
Gaadan Punsalpaamuu ◽  
Lyudmila Shumilovskikh ◽  
Hermann Behling
Keyword(s):  
High Resolution ◽  
Water Availability ◽  
National Park ◽  
Environmental Changes ◽  
Anthropogenic Impacts ◽  
Climatic Conditions ◽  
Forest Steppe ◽  
Permafrost Degradation ◽  
Rainfall Events ◽  
The Impact

The ‘Altai Tavan Bogd’ National Park in the north-western part of the Mongolian Altai, Central Asia, is located in a forest-steppe ecosystem. It occurs under the influence of extreme continental and montane climate and is sensitive to natural and anthropogenic impacts. High-resolution (<20 years per sample) multi-proxy data of pollen, non-pollen palynomorphs (NPPs), macro-charcoal, diatoms, and XRF scanning from radiocarbon-dated lacustrine sediments reveal various environmental changes and the impact of different settlement periods for the late-Holocene. From 1350 to 820 cal. yr BP (AD 600–1130), the distribution of grass steppe indicates a climate similar to present-day conditions. Rapid improvements of climatic conditions (e.g. increased rainfall events) possibly favored a recovery of forest-steppe encouraging nomadic movements into alpine areas. In the period from 820 to 400 cal. yr BP (AD 1130–1550), the decline of forested areas suggests an increasingly drier and possibly colder climate. Some political shifts during the Mongol Empire (744–582 cal. yr BP; AD 1206–1368) favored variations in nomadic grazing habits. After 400 cal. yr BP (AD 1550), moisture and temperature increased slightly, and from ca. 40 cal. yr BP (AD 1910) to present, annual temperature continued to increase more markedly favoring an additional water availability due to permafrost degradation. Diatom data suggest several intervals of increased water availability in all periods which might have caused erosion due to heavier rainfall events or increased snow melt. Immediately after most of these high-water intervals, NPP data reveal periods of increased grazing activities in the area.

Rock avalanches at Texas Creek, British Columbia

1990 ◽  
Vol 27 (10) ◽  
pp. 1316-1329 ◽  
Author(s):  
J. M. Ryder ◽  
M. J. Bovis ◽  
M. Church
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
Landslide Dam ◽  
Steep Slope ◽  
Alluvial Fan ◽  
Fraser River ◽  
Geological Evidence ◽  
Sudden Failure ◽  
Rock Avalanches ◽  
A Site

At least two rock avalanches have occurred during Holocene time at the confluence of Texas Creek and Fraser River, about 300 km upstream from Vancouver. The morphological features of the avalanche debris are well preserved, and its stratigraphic relations are well exposed. Failures occurred in fractured argillites adjacent to a small pluton at a site where a steep slope is maintained as a result of undercutting by Fraser River. The first and largest (45 × 106 m3) avalanche occurred during middle to late Holocene time. Debris infilled the postglacial gorges of the streams and spread across a partly dissected alluvial fan. An anomalous ridge on the avalanche deposit reflects the influence of a buried scarp on debris motion and failure in underlying Pleistocene silts. A sharp contact between debris of differing lithologies suggests that the avalanche moved as a coherent mass. A second, smaller (about 7.2 × 106 m3) avalanche occurred about 120014C years ago.Archaeological and geological evidence from sites upstream suggests that the second avalanche impounded Fraser River, causing backwater sedimentation at Lillooet and blocking the migration of salmon. Another avalanche could occur at this site, with similar effects; sudden failure of the landslide dam could generate a catastrophic flood downstream.

scholarly journals Environmental changes in the northern Altai during the last millennium documented in Lake Teletskoye pollen record

2007 ◽  
Vol 67 (3) ◽  
pp. 394-399 ◽  
Author(s):  
Andrei A. Andreev ◽  
Roberto Pierau ◽  
Ivan A. Kalugin ◽  
Andrei V. Daryin ◽  
Lyubov G. Smolyaninova ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Vegetation History ◽  
Climatic Conditions ◽  
Ice Age ◽  
Pollen Record ◽  
Last Millennium ◽  
Climate Conditions ◽  
Lake Teletskoye ◽  
Pollen Concentrations ◽  
Siberian Pine

AbstractA high-resolution pollen record from Lake Teletskoye documents the climate-related vegetation history of the northern Altai Mountain region during the last millennium. Siberian pine taiga with Scots pine, fir, spruce, and birch dominated the vegetation between ca. AD 1050 and 1100. The climate was similar to modern. In the beginning of the 12th century, birch and shrub alder increased. Lowered pollen concentrations and simultaneous peaks in herbs (especially Artemisia and Poaceae), ferns, and charcoal fragments point to colder and more arid climate conditions than before, with frequent fire events. Around AD 1200, regional climate became warmer and more humid than present, as revealed by an increase of Siberian pine and decreases of dry herb taxa and charcoal contents. Climatic conditions were rather stable until ca. AD 1410. An increase of Artemisia pollen may reflect slightly drier climate conditions between AD 1410 and 1560. Increases in Alnus, Betula, Artemisia, and Chenopodiaceae pollen and in charcoal particle contents may reflect further deterioration of climate conditions between AD 1560 and 1810, consistent with the Little Ice Age. After AD 1850 the vegetation gradually approached the modern one, in conjunction with ongoing climate warming.

scholarly journals Western equatorial African forest-savanna mosaics: a legacy of late Holocene climatic change?

2009 ◽  
Vol 5 (1) ◽  
pp. 341-367 ◽  
Author(s):  
A. Ngomanda ◽  
A. Chepstow-Lusty ◽  
M. Makaya ◽  
C. Favier ◽  
P. Schevin ◽  
...  
Keyword(s):  
Environmental History ◽  
Late Holocene ◽  
Environmental Changes ◽  
Elaeis Guineensis ◽  
Coastal Region ◽  
Climatic Conditions ◽  
Rapid Decline ◽  
Pollen Record ◽  
Secondary Forests ◽  
Equatorial Africa

Abstract. Past vegetation and climate changes reconstructed using two pollen records from Lakes Maridor and Nguène, Gabon, provide new insights into the environmental history of western equatorial African rainforests during the last 4500 cal yr BP. The Lake Maridor pollen record indicates that the coastal savannas of western equatorial Africa did not exist during the mid-Holocene and instead the region was covered by evergreen rainforests. In the Lake Nguène pollen record, a rapid decline of hygrophilous evergreen rainforest occurred around 4000 cal yr BP, synchronously with grassland expansion around Lake Maridor. The establishment of coastal savannas in Gabon suggests decreasing humidity at the onset of the late Holocene. The marked reduction in evergreen rainforest and subsequent savanna expansion was associated with the colonization of secondary forests dominated by the palm, Elaeis guineensis, in the coastal region and the shrub, Alchornea cordifolia, further inland. A return to wetter climatic conditions from about 1400 cal yr BP led to the renewed spread of evergreen rainforest inland, whereas a forest-savanna mosaic still persists in the coastal region. There is no evidence to suggest that the major environmental changes observed are driven by human impact.

Fossil rodents in Mylodon Cave as indicators of late Pleistocene–Holocene environmental evolution in southern Chile

2021 ◽  
pp. 1-17
Author(s):  
Ulyses F.J. Pardiñas ◽  
Luis Borrero ◽  
Fabiana M. Martin ◽  
Mauricio Massone ◽  
Fernando J. Fernández
Keyword(s):  
Late Pleistocene ◽  
Small Mammal ◽  
Late Holocene ◽  
Environmental Changes ◽  
First Record ◽  
Climatic Conditions ◽  
Southern Chile ◽  
Environmental Evolution ◽  
Local Conditions ◽  
Almost All

Abstract We conducted the first taphonomic and paleoenvironmental study based on late Pleistocene–Holocene small mammal remains recovered from the famous Mylodon Cave (Cerro Benítez area, Última Esperanza, Chile). Most of the analyzed material came from the extensive excavations made by Earl Saxon in 1976. We also studied late Holocene small mammal samples of the neighboring rock shelter Dos Herraduras 1. Analyzed remains were mostly produced by owls, probably living inside the caves. In Mylodon Cave, the higher values of girdle bones are consistent with a windblown litter. We recorded nine species of rodents, seven cricetids, and two caviomorphs; almost all the identified taxa integrate recent local communities. Late Pleistocene–Holocene assemblages are characterized by the chinchilla rat Euneomys, indicating unforested areas around the caves under cold and moist climatic conditions. Middle Holocene amelioration is reflected by incremental rodent species richness, including the first record of taxa clearly associated with forest (e.g., Abrothrix lanosa). Late Holocene assemblages are markedly stable, indicating local conditions similar to the current (historical) environment. Quaternary rodents from Cerro Benítez area do not indicate abrupt environmental changes during middle–late Holocene, but a progressive trend towards forest increase.

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