Pollen size of Betula in northern Alaska and the interpretation of late Quaternary vegetation records

1991 ◽  
Vol 69 (8) ◽  
pp. 1666-1672 ◽  
Author(s):  
Mary E. Edwards ◽  
Janice C. Dawe ◽  
W. Scott Armbruster
Keyword(s):  
Late Quaternary ◽  
Temporal Trends ◽  
Birch Pollen ◽  
Size Variation ◽  
Pollen Size ◽  
Betula Glandulosa ◽  
Dwarf Birch ◽  
Fossil Records ◽  
Northern Alaska ◽  
Significant Size

It is commonly asserted in paleoecological studies that shrub birch tends to have smaller pollen than tree birch, but this is poorly documented for Alaskan taxa. We measured freshly dehisced pollen from 55 plants in four northern Alaskan taxa, Betula resinifera (tree birch), Betula glandulosa (shrub birch), Betula nana ssp. exilis (dwarf birch), and Betula resinifera × glandulosa (hybrid). No significant differences existed between mean pollen sizes of any taxa. Betula glandulosa showed significant size variation among sites. Increase in birch-pollen size with time observed in some late Quaternary fossil records from northern Alaska cannot be safely attributed to a change from shrub to tree-dominated vegetation. Alternative explanations for temporal trends in pollen size are (i) evolution of populations, (ii) an environmental effect on pollen size, and (iii) local extinction of a previously widespread taxon. Key words: Alaska, Beringia, Betula, late Quaternary, pollen size.

scholarly journals Addendum: FosSahul 2.0, an updated database for the Late Quaternary fossil records of Sahul

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Katharina J. Peters ◽  
Frédérik Saltré ◽  
Tobias Friedrich ◽  
Zenobia Jacobs ◽  
Rachel Wood ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Fossil Records

A Preliminary Report of Changing Quaternary Mammal Faunas in Subalpine New Guinea

1993 ◽  
Vol 40 (1) ◽  
pp. 117-126 ◽  
Author(s):  
Geoffrey Hope ◽  
Tim Flannery ◽  
Boeardi
Keyword(s):  
Preliminary Report ◽  
Late Quaternary ◽  
Montane Forest ◽  
Mammal Species ◽  
Irian Jaya ◽  
Fluvial Deposits ◽  
Unknown Species ◽  
Holocene Record ◽  
Fossil Records ◽  
Mammal Faunas

AbstractThe faunas found in the mountains of central Irian Jaya have experienced dramatic changes through the late Quaternary. Remains of two previously unknown species of large marsupial, Maokopia ronaldi and Protemnodon hopei, have been recovered from unrelated cave and fluvial deposits which today occur in dense upper montane forest. Direct dating of the finds has not as yet been possible, but stratigraphic, sedimentologic, and palynologic evidence indicates that these species lived near a climatic treeline in subalpine grassland in the late Pleistocene. At higher altitudes a rockshelter provided the second known mid-Holocene record of Thylogale christenseni and Thylogale sp. cf. brunii, apparently extinct grassland wallabies. The two largest remaining subalpine mammal species are being locally exterminated by hunting, leaving only a large murid, Mallomys gunung, which weighs less than 2.0 kg. The area thus records the disappearance of a grassland-adapted fauna. The possum Pseudocheirops cupreus dominates in modem hunting returns, although this species is totally absent from the local fossil records. It may thus be in the process of invading a vacated and disturbed niche from the upper montane forest.

scholarly journals Bird populations and species lost to Late Quaternary environmental change and human impact in the Bahamas

2020 ◽  
Vol 117 (43) ◽  
pp. 26833-26841 ◽  
Author(s):  
David W. Steadman ◽  
Janet Franklin
Keyword(s):  
Late Pleistocene ◽  
Migratory Birds ◽  
Late Quaternary ◽  
Bird Communities ◽  
Greater Antilles ◽  
The Bahamas ◽  
Bird Populations ◽  
Modern Distribution ◽  
Distributional Information ◽  
Fossil Records

Comparing distributional information derived from fossils with the modern distribution of species, we summarize the changing bird communities of the Bahamian Archipelago across deep ecological time. While our entire dataset consists of 7,600+ identified fossils from 32 sites on 15 islands (recording 137 species of resident and migratory birds), we focus on the landbirds from four islands with the best fossil records, three from the Late Pleistocene (∼25 to 10 ka [1,000 y ago]) and one from the Holocene (∼10 to 0 ka). The Late Pleistocene sites feature 51 resident species that have lost one or more Bahamian populations; 29 of these species do not occur in any of the younger Holocene sites (or in the Bahamas today). Of these 29 species, 17 have their closest affinities to species now or formerly living in Cuba and/or North America. A set of 27 species of landbirds, most of them extant somewhere today, was more widespread in the Bahamas in the prehistoric Holocene (∼10 to 0.5 ka) than they are today; 16 of these 27 species were recorded as Pleistocene fossils as well. No single site adequately captures the entire landbird fauna of the combined focal islands. Information from all sites is required to assess changes in Bahamian biodiversity (including endemism) since the Late Pleistocene. The Bahamian islands are smaller, flatter, lower, and more biotically depauperate than the Greater Antilles, resulting in more vulnerable bird communities.

scholarly journals Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome

Polar Biology ◽  
2017 ◽  
Vol 40 (11) ◽  
pp. 2265-2278 ◽  
Author(s):  
Isabel C. Barrio ◽  
Elin Lindén ◽  
Mariska Te Beest ◽  
Johan Olofsson ◽  
Adrian Rocha ◽  
...  
Keyword(s):  
Temperature And Precipitation ◽  
Betula Glandulosa ◽  
Dwarf Birch ◽  
Invertebrate Herbivory

The population biology of the arctic dwarf birch, Betula glandulosa: seed rain and the germinable seed bank

1988 ◽  
Vol 66 (10) ◽  
pp. 2055-2061 ◽  
Author(s):  
I. Michael Weis ◽  
Luise A. Hermanutz
Keyword(s):  
Seed Bank ◽  
Weight Distribution ◽  
Population Biology ◽  
Early Spring ◽  
Seed Rain ◽  
The Arctic ◽  
Low Density ◽  
Soil Cores ◽  
Betula Glandulosa ◽  
Dwarf Birch

The seed rain and seed bank of arctic dwarf birch, Betula glandulosa, were studied at Kuujjuaq, Que., and Tarr Inlet, near Iqaluit, N.W.T. At each site dispersing seeds were captured in sticky traps in three adjacent plots having locally high and low birch densities; soil cores were collected in parallel. Trap data indicate that birch samaras disperse principally during late fall and early spring. The number of samaras dispersed was significantly greater at Kuujjuaq than near Iqaluit and was greater in high- than in low-density areas. Samaras collected at Kuujjuaq were significantly heavier (x = 0.19 mg) than those from Tarr Inlet (x = 0.10 mg). Germination showed an asymptotic exponential weight dependence. From the weight distribution of samaras, we expected germination of 69.7% of samaras from Kuujjuaq. Few viable propagules were found in collections from the Iqaluit area; from their weight distribution 0.38% were expected to germinate. We predicted emergence from soil cores, using seed-trap and germination data, and tested predictions under greenhouse conditions. Observations and predictions agreed for low-density areas. At Kuujjuaq 248 emergences/m2 were predicted and 229 observed; at Iqaluit no emergences were predicted and none observed. In high-density plots at Kuujjuaq 9292 emergences/m2 were predicted and 2164 observed. Corresponding rates for Iqaluit were 2 and 17 emergences/m2, respectively. Differences in seed banks and recruitment indicate differences in the structure, dynamics, and reproductive biology of populations at the two sites.

Late Quaternary Vegetational Change in the Kotzebue Sound Area, Northwestern Alaska

1985 ◽  
Vol 24 (3) ◽  
pp. 307-321 ◽  
Author(s):  
Patricia M. Anderson
Keyword(s):  
Late Quaternary ◽  
Sediment Cores ◽  
Western North America ◽  
Betula Nana ◽  
Vegetational Change ◽  
Shrub Tundra ◽  
Kotzebue Sound ◽  
Northern Alaska ◽  
North Western ◽  
Pollen Records

Two sediment cores from Kaiyak and Squirrel lakes in northwestern Alaska yielded pollen records that date to ca. 39,000 and 27,000 yr B.P., respectively. Between 39,000 and 14,000 yr B.P., the vegetation around these lakes was dominated by Gramineae and Cyperaceae with someSalixand possiblyBetula nana/glandulosaforming a local, shrub component of the vegetation.Betulapollen percentages increased about 14,000 yr B.P., indicating the presence of a birchdominated shrub tundra.Alnuspollen appeared at both sites between 9000 and 8000 yr B.P., andPiceapollen (mostlyP. mariana) arrived at Squirrel Lake about 5000 yr B.P. The current foresttundra mosaic around Squirrel Lake was established at this time, whereas shrub tundra existed near Kaiyak Lake throughout the Holocene. When compared to other pollen records from north-western North America, these cores (1) represent a meadow component of lowland. Beringian tundra between 39,000 and 14,000 yr B.P., (2) demonstrate an early Holocene arrival ofAlnusin northwestern Alaska that predates most otherAlnushorizons in northern Alaska or northwestern Canada, and (3) show an east-to-west migration ofPiceaacross northern Alaska from 9000 to 5000 yr B.P.

Late Quaternary Pollen Records from the Kobuk and Noatak River Drainages, Northwestern Alaska

1988 ◽  
Vol 29 (3) ◽  
pp. 263-276 ◽  
Author(s):  
Patricia M. Anderson
Keyword(s):  
Picea Glauca ◽  
Regional Differences ◽  
Late Quaternary ◽  
Limited Effect ◽  
Local Expansion ◽  
Thermal Maximum ◽  
Pollen Diagrams ◽  
Northern Alaska ◽  
River Drainages ◽  
Pollen Records

Pollen diagrams from Joe and Niliq Lakes date to ca. 28,000 and 14,000 yr B.P., respectively. Mesic shurb tundra grew near Joe Lake ca. 28,000 to 26,000 yr B.P. with localPopuluspopulations prior to ca. 27,000 yr B.P. Shrub communities decreased as climate changed with the onset of Itkillik II glaciation (25,000 to 11,500 yr B.P.), and graminoid-dominated tundra characterized vegetation ca. 18,500 to 13,500 yr B.P. Herb tundra was replaced by shrubBetulatundra near both sites ca. 13,500 yr B.P. with local expansion ofPopulusca. 11,000 to 10,000 yr B.P. andAlnusca. 9000 yr B.P. MixedPicea glauca/P. marianawoodland was established near Joe Lake ca. 6000 yr B.P. These pollen records when combined with others from northern Alaska and northwestern Canada indicate (1) mesic tundra was more common in northwestern Alaska than in northeastern Alaska or northwestern Canada during the Duvanny Yar glacial interval (25,000 to 14,000 yr B.P.); (2) with deglaciation, shrubBetulaexpanded rapidly in northwestern Alaska but slowly in areas farther east; (3) an early postglacial thermal maximum occurred in northwestern Alaska but had only limited effect on vegetation; and (4) pollen patterns in northern Alaska and northwestern Canada suggest regional differences in late Quaternary climates.

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