Late Wisconsin and Holocene vegetational history of the Upper Koyukuk region, Brooks Range, AK

1985 ◽  
Vol 63 (3) ◽  
pp. 616-626 ◽  
Author(s):  
Mary E. Edwards ◽  
Patricia M. Anderson ◽  
Harriet L. Garfinkel ◽  
Linda B. Brubaker
Keyword(s):  
Picea Mariana ◽  
Picea Glauca ◽  
Vegetation History ◽  
High Elevation ◽  
Populus Balsamifera ◽  
Before Present ◽  
Brooks Range ◽  
Arrival Times ◽  
Pollen Rain ◽  
Lower Site

Three pollen diagrams provide information on late Wisconsin and Holocene vegetation history at high elevation and midelevations (1000 and 600 m) in the east-central Brooks Range. After the retreat of glacial ice and until about 12 000 years before present, the vegetation was a tundra, dominated by Salix, Cyperaceae, Gramineae, Artemisia, and other herbaceous taxa. However, because the early pollen spectra do not have close modern analogs, the detailed composition and ecology of this tundra cannot be inferred. Between ca. 12 000 and ca. 8 000 years before present, Betula nana–glandulosa was the dominant pollen producer at both elevations; a significant ericaceous component was present in the vegetation of the alpine sites, but not at the lower elevation site. During the period 10 500 – 8 500 years before present, Populus balsamifera and Juniperus were probably abundant at the lower site and may also have been present at the higher sites, where they are now absent. Picea glauca, Alnus spp., Picea mariana, and Betula papyrifera became established at the lower site between ca. 8500 and 6000 years before present. None of these species currently grows at the high sites, but their arrival at lower elevations is represented in the regional pollen rain at these sites. The arrival times of Picea glauca and Picea mariana in the study area are consistent with the hypothesis that P. glauca preceded P. mariana into the central Brooks Range.

A Late Wisconsin and Holocene Vegetation History from the Central Brooks Range: Implications for Alaskan Palaeoecology

1983 ◽  
Vol 20 (2) ◽  
pp. 194-214 ◽  
Author(s):  
Linda B. Brubaker ◽  
Harriet L. Garfinkel ◽  
Mary E. Edwards
Keyword(s):  
Picea Glauca ◽  
Environmental Changes ◽  
Vegetation History ◽  
Vegetation Changes ◽  
Populus Balsamifera ◽  
Brooks Range ◽  
Walker Lake ◽  
Linear Discriminant ◽  
Pollen Influx ◽  
Total Pollen

Five pollen diagrams reveal late Wisconsin and Holocene vegetation changes in the Walker Lake/Alatna Valley region of the central Brooks Range, approximately 100 km west of the area studied by D. A. Livingstone (1955, Ecology 36, 587–600). New insights into the vegetation history of this region are provided by calculations of pollen influx and by the use of linear discriminant analysis to separate Picea glauca and P. mariana pollen. Three major pollen zones are identified: (1) a basal herb zone, characterized by high percentages of Cyperaceae, Gramineae, Salix, and Artemisia, and low total pollen influx; (2) a shrub Betula zone with increased total pollen influx and very high percentages of Betula pollen, predominantly in the size range of B. nana and B. glandulosa; and (3) and Alnus zone dominated by Alnus pollen. Lakes currently within the boreal forest or near tree line show relatively high percentages of Picea pollen in the Alnus zone. Several striking vegetation changes occurred between ca. 10,000 and 7000 yr B.P. Between ca. 11,000 and 10,000 yr B.P., Populus balsamifera pollen percentages as great as 30% indicate that this species was present at low-elevation sites near Walker Lake. These populations declined abruptly ca. 10,000 yr ago and have never regained prominence. About 8500 yr B.P., Picea glauca pollen reached 10–15%, indicating the arrival of P. glauca in or near the study area. P. glauca populations evidently decreased ca. 8000 yr ago, when Picea pollen percentages and influx fell to low values. About 7000 yr B.P., Alnus pollen percentages and influx rose sharply as alder shrubs became established widely. Picea once more expanded ca. 5000 yr ago, but these populations were dominated by P. mariana rather than P. glauca, which increased slowly at this time and may still be advancing northward. Some vegetation changes have been remarkably synchronous over wide areas of interior Alaska, and probably reflect responses of in situ vegetation to environmental changes, but others may reflect the lagged responses of species migrating into new areas.

Postglacial vegetation history of the Mariana Lake region, Alberta

1994 ◽  
Vol 31 (2) ◽  
pp. 418-425 ◽  
Author(s):  
M. J. Hutton ◽  
G. M. MacDonald ◽  
R. J. Mott
Keyword(s):  
Picea Mariana ◽  
Picea Glauca ◽  
Vegetation History ◽  
Fossil Pollen ◽  
Pollen Record ◽  
Sparse Vegetation ◽  
Lake Region ◽  
History Of

A fossil pollen record extending from 11 300 BP to the present was recovered from Mariana Lake, Alberta (55°57′N, 112°01′W). Initially, the region had a sparse vegetation dominated by forbs and graminoids, which at approximately 10 500 BP succeeded to Picea glauca forest. Picea mariana – Sphagnum peatlands began to develop between 10 000 and 9500 BP. After 9000 BP Sphagnum-dominated sites decreased; P. glauca declined while Betula increased. From 7500 to 5500 BP Populus reached its maximum Holocene representation in the vegetation. Sphagnum-dominated peatlands almost disappeared. The changes following 9000 BP were likely caused by increased aridity. However, the presence of P. mariana, Abies, and Larix in the pollen record suggests that mesic sites remained. Beginning at 6500–6000 BP the extent of Sphagnum peatlands began to increase. Abies declined in importance following 5000 BP, possibly due to paludification of mesic sites. The expansion of parkland into central Alberta during the mid-Holocene did not extend to Mariana Lake. However, Mariana Lake records changes in vegetation resulting from increased aridity in the early to mid-Holocene which are not apparent at more northerly sites in Alberta.

Modern pollen rain and vegetation of the St. Elias Mountains, Yukon Territory

1977 ◽  
Vol 55 (18) ◽  
pp. 2367-2382 ◽  
Author(s):  
H. J. B. Birks
Keyword(s):  
Picea Glauca ◽  
Yukon Territory ◽  
Sample Type ◽  
Vegetation Types ◽  
Populus Balsamifera ◽  
Modern Pollen ◽  
Pollen Content ◽  
Pollen Rain ◽  
Shrub Tundra ◽  
Community Types

The vegetation of the area east of the Klutlan Glacier in the St. Elias Mountains is described with the methods of European phytosociology. Four major vegetation types are recognized: Picea glauca forests, Populus balsamifera forests, Betula glandulosa shrub–tundra, and Dryas integrifolia tundra.The modern pollen assemblages deposited in these vegetation types are determined by pollen analysis of surface moss polsters, lake muds, and moss samples from sedge swamps. Numerical analyses of the surface spectra indicate that spectra from the Dryas tundra and from the Populus forests are distinctive in their pollen composition. The variation in the percentage pollen content of samples from the Picea forests and the shrub–tundra is so great, even when spectra from a single sample type are considered, that no reliable distinctions can be made in modern pollen spectra from these two community types.

Gas exchange and growth of three arctic tree-line tree species under different soil temperature and drought preconditioning regimes

1996 ◽  
Vol 74 (5) ◽  
pp. 686-693 ◽  
Author(s):  
Simon M. Landhäusser ◽  
Ross W. Wein ◽  
Petra Lange
Keyword(s):  
Soil Temperature ◽  
Picea Mariana ◽  
Tree Species ◽  
Withholding Treatment ◽  
The Arctic ◽  
Betula Papyrifera ◽  
Tree Line ◽  
Populus Balsamifera ◽  
Soil Temperatures ◽  
Net Assimilation

Low soil temperatures and water availability are thought to be major factors determining the distribution of tree species at the arctic tree line. A comparative study examined the response of Betula papyrifera, Populus balsamifera, and Picea mariana seedlings to different soil temperatures and drought regimes in a growth chamber experiment. Morphological and ecophysiological responses (net assimilation rate, stomatal conductance to water vapour, and residual conductance) of these tree line tree species were measured and compared. Mean biomass accumulation of the deciduous species was greater than that of Picea mariana with increasing soil temperatures. Root biomass showed an increase of 30% in the three species between the soil temperatures of 3 and 15 °C. Response of ecophysiological variables to increased soil temperature was greater in B. papyrifera and Populus balsamifera than in Picea mariana. In a second experiment, drought-preconditioned B. papyrifera and Populus balsamifera seedlings were subjected to a 6-day water-withholding treatment. Drought decreased shoot mass and increased the root to shoot ratio equally in B. papyrifera and Populus balsamifera. Drought-preconditioned B. papyrifera and Populus balsamifera seedlings responded differently to the 6-day water-withholding treatment. Betula papyrifera used a water-conserving strategy and maintained low net assimilation rates and low water use after drought preconditioning, whereas in Populus balsamifera greater net assimilation rates were associated with drought preconditioning. These results are consistent with the distribution of these three tree species at the arctic tree line. Keywords: Picea mariana, Populus balsamifera, Betula papyrifera, drought preconditioning, soil temperature, arctic tree line.

Short-term effects of cut-to-length versus full-tree harvesting on conifer regeneration in jack pine, mixedwood, and black spruce forests in Manitoba

2004 ◽  
Vol 34 (9) ◽  
pp. 1938-1945 ◽  
Author(s):  
Isobel Waters ◽  
Steven W Kembel ◽  
Jean-François Gingras ◽  
Jennifer M Shay
Keyword(s):  
Picea Mariana ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Black Spruce ◽  
Abies Balsamea ◽  
Jack Pine ◽  
Tree Regeneration ◽  
Understorey Vegetation ◽  
Advance Regeneration ◽  
The Impact

This study compares the effects of full-tree versus cut-to-length forest harvesting methods on tree regeneration in jack pine (Pinus banksiana Lamb.), mixedwood (Picea glauca (Moench) Voss – Populus tremuloides Michx. – Abies balsamea (L.) Mill.), and black spruce (Picea mariana (Mill.) BSP) sites in southeastern Manitoba, Canada. We surveyed tree regeneration densities, disturbance characteristics, and understorey vegetation in replicated control and harvested plots in each site type preharvest (1993) and 1 and 3 years postharvest (1994, 1996). In jack pine sites, the full-tree harvest method promoted regeneration of Pinus banksiana through increased disturbance of soil and the moss layer, and decreased slash deposition relative to the cut-to-length method. Conversely, in mixedwood sites the cut-to-length method resulted in less damage to advance regeneration and proved better at promoting postharvest regeneration of Abies balsamea and Picea glauca relative to the full-tree method. In black spruce sites, there were few differences in the impact of the two harvesting methods on regeneration of Picea mariana, which increased in frequency and density after both types of harvesting.

Pollen Analysis of Digger's Creek Bog, Kosciuszko National Park: Vegetation History and Tree-line Change

1999 ◽  
Vol 47 (5) ◽  
pp. 725 ◽  
Author(s):  
A. R. H. Martin
Keyword(s):  
National Park ◽  
Vegetation History ◽  
Early 20Th Century ◽  
Peat Bog ◽  
Tree Line ◽  
Before Present ◽  
Near Surface ◽  
Lake Zone ◽  
Arboreal Pollen ◽  
Eastern Australia

Digger's Creek Bog, an Empodisma minus–Callistemon pityoides–Sphagnum cristatum shrubby subalpine peat bog, alt. c. 1690 m, not far below local altitudinal tree-line, began development > 10 000 years before present as an Astelia sp.–Carex alpine soak. Surrounding vegetation was a grassy alpine herbfield with many Asteraceae, Apiaceae and Gentianella diemensis, corresponding to the regional Club Lake Zone C, dated to the same period. Astelia died out c. 6500 years before present approximately at the Club Lake C/D 1 boundary, marked by spread of Pomaderris in subjacent montane forests. Thereafter, shrubs, mainly Myrtaceae and Epacridaceae, and Restionaceae (Empodisma and Restio australis) dominated the bog. Epacris cf. paludosa and C. pityoides seem to have been the earliest shrubs to invade, Baeckea, probably B. gunniana, and Richea continentis reaching maximum prominence 5000–3000 years before present. Sphagnum was uncommon until recently. Regional arboreal pollen enable comparisons with other sites in south-eastern Australia but immigration of the tree-line species Eucalyptus pauciflora subsp. niphophila (snowgum) is not well expressed in the pollen spectra. Surface and near-surface counts of this species are higher than at any preceding time, and correspond most closely to surface counts in adjacent young snowgum woodland. The co-occurrence of weed pollens, probably associated with the late 19th and early 20th century practice of summer pasturing stock on the alpine–subalpine tract, suggests that pasturing and burning, responsible for widespread severe fires on this range, led both to the formation of dense even-aged snowgum woodland that had been open and patchy at this altitude, and a spread of Sphagnum on the bog surface.

Humid to Arid to Subhumid Vegetation Shift on Pilliga Sandstone, Ulungra Springs, New South Wales

1989 ◽  
Vol 32 (2) ◽  
pp. 182-192 ◽  
Author(s):  
J.R. Dodson ◽  
R.V.S. Wright
Keyword(s):  
Vegetation Cover ◽  
Vegetation History ◽  
Arid Zone ◽  
New South ◽  
New South Wales ◽  
Vegetation Shift ◽  
South Wales ◽  
Shrub Steppe ◽  
Pollen Rain ◽  
Open Forests

AbstractThe Pilliga Sandstone region of the northwest slope of New South Wales has a natural vegetation cover of sclerophyllous relatively closed to open forests with a largely heathy understorey, and a warm, subhumid and continental climate. Pollen analysis of spring-fed deposits gives a vegetation history extending from at least 30,000 yr B.P. to the late Holocene. Tree pollen became scarce after about 25,000 yr B.P. and an assemblage dominated by Chenopodiaceae, Liguliflorae, Tubuliflorae, and probably Poaceae developed. No similar assemblage is known from present pollen rain studies carried out in Australia. However, it clearly represents a treeless open shrub-steppe formation and therefore an arid or semiarid environment. The site thus provides evidence of an eastward late Pleistocene extension of the arid zone in Australia, and is the first full-glacial vegetation record between 20° and 35° latitude in Australia. The present vegetation cover did not become reestablished until the beginning of the Holocene, which raises questions about the form in which Pilliga Sandstone vegetation survived full-glacial conditions.

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