Late-Glacial Vegetation Associated with Caribou and Mastodon in Central Indiana

AbstractThe Christensen Mastodon Site, located in central Indiana, contains a rich assemblage of vertebrates (including mastodon, caribou, and giant beaver), invertebrates, and plant macrofossilsin situin lake and bog sediments of late-glacial age. Studies of pollen and plant macrofossils suggest the existence of open, white spruce-dominated boreal forests from > 14,000 yr B.P. to ca. 13,000 yr B.P. The regional decline of spruce, local occurrence of black spruce, white spruce, and larch, immigration of many hardwood taxa (e.g., ash, oak, elm), and the initiation of bog development are recorded beginning about 13,000 yr B.P. Recent reconstructions of late-glacial and early postglacial vegetational changes provide a context for understanding the disappearance of mastodons. The dramatic and rapid restriction of boreal forests along the retreating ice margin from 11,000 to 9000 yr B.P. may have caused a substantial reduction of mastodon populations. A diminished population would be more susceptible to small-scale, stochastic events such as short-term extremes of weather, outbreaks of disease, or predation pressure from paleoindian hunters.

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Summary and Synthesis: Past and Future Changes in the Alaskan Boreal Forest

Alaska's Changing Boreal Forest ◽

10.1093/oso/9780195154313.003.0028 ◽

2006 ◽

Author(s):

Marilyn W. Walker ◽

Mary E. Edwards

Keyword(s):

Boreal Forest ◽

Bark Beetles ◽

Fire Regime ◽

Black Spruce ◽

Rapid Change ◽

White Spruce ◽

Late Glacial ◽

Fire Frequency ◽

Tree Resistance ◽

Forest Sites

Historically the boreal forest has experienced major changes, and it remains a highly dynamic biome today. During cold phases of Quaternary climate cycles, forests were virtually absent from Alaska, and since the postglacial re-establishment of forests ca 13,000 years ago, there have been periods of both relative stability and rapid change (Chapter 5). Today, the Alaskan boreal forest appears to be on the brink of further significant change in composition and function triggered by recent changes that include climatic warming (Chapter 4). In this chapter, we summarize the major conclusions from earlier chapters as a basis for anticipating future trends. Alaska warmed rapidly at the end of the last glacial period, ca 15,000–13,000 years ago. Broadly speaking, climate was warmest and driest in the late glacial and early Holocene; subsequently, moisture increased, and the climate gradually cooled. These changes were associated with shifts in vegetation dominance from deciduous woodland and shrubland to white spruce and then to black spruce. The establishment of stands of fire-prone black spruce over large areas of the boreal forest 5000–6000 years ago is linked to an apparent increase in fire frequency, despite the climatic trend to cooler and moister conditions. This suggests that long-term features of the Holocene fire regime are more strongly driven by vegetation characteristics than directly by climate (Chapter 5). White spruce forests show decreased growth in response to recent warming, because warming-induced drought stress is more limiting to growth than is temperature per se (Chapters 5, 11). If these environmental controls persist, projections suggest that continued climate warming will lead to zero net annual growth and perhaps the movement of white spruce to cooler upland forest sites before the end of the twenty-first century. At the southern limit of the Alaskan boreal forest, spruce bark beetle outbreaks have decimated extensive areas of spruce forest, because warmer temperatures have reduced tree resistance to bark beetles and shortened the life cycle of the beetle from two years to one, shifting the tree-beetle interaction in favor of the insect (Chapter 9).

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Splitting in Fire-Killed Trees in the Boreal Forest of Alberta

Northern Journal of Applied Forestry ◽

10.1093/njaf/20.4.167 ◽

2003 ◽

Vol 20 (4) ◽

pp. 167-174

Author(s):

Nobutaka Nakamura ◽

Paul M. Woodard ◽

Lars Bach

Keyword(s):

Boreal Forest ◽

Boreal Forests ◽

Black Spruce ◽

Lodgepole Pine ◽

White Spruce ◽

Balsam Fir ◽

Crown Fire ◽

In Fire ◽

Solar Angle

Abstract Tree boles in the boreal forests of Alberta, Canada will split once killed by a stand-replacing crown fire. A total of 1,485 fire-killed trees were sampled, 1 yr after burning, in 23 plots in 14 widely separated stands within a 370,000 ha fire. Sampling occurred in the Upper and Lower Foothills natural subregions. The frequency of splitting varied by species but averaged 41% for all species. The order in the frequency of splitting was balsam fir, black spruce, white spruce and lodgepole pine. The type of splitting (straight, spiral, or multiple) varied by species, as did the position of the split on the tree bole. Aspect or solar angle was not statistically related to the type or occurrence of splitting.

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An overview of the vegetation and soils of the floodplain ecosystems of the Tanana River, interior Alaska

Canadian Journal of Forest Research ◽

10.1139/x93-117 ◽

1993 ◽

Vol 23 (5) ◽

pp. 889-898 ◽

Cited By ~ 101

Author(s):

L.A. Viereck ◽

C.T. Dyrness ◽

M.J. Foote

Keyword(s):

Forest Succession ◽

Black Spruce ◽

White Spruce ◽

Organic Layer ◽

Organic Layers ◽

Balsam Poplar ◽

Feather Mosses ◽

Successional Stages ◽

Salt Affected Soils ◽

Stochastic Events

The soils and vegetation of 12 stages of forest succession on the floodplain of the Tanana River are described. Succession begins with the invasion of newly deposited alluvium by willows (Salix spp.) and develops through a willow–alder (Alnustenuifolia Nutt.) stage to forest stands of balsam poplar (Populusbalsamifera L.), followed by white spruce (Piceaglauca (Moench) Voss), and finally black spruce (Piceamariana (Mill.) B.S.P.). The principal changes in substrate characteristics during the successional sequence are (i) change from sand to silt loam, (ii) increase in terrace height and distance from the water table, (iii) development of a forest floor, first of leaf litter and then live and dead feather mosses, (iv) burial of organic layers by flooding, and (v) the development of permafrost as soils are insulated by a thick organic layer. Soils and vegetation of six stands occurring in three successional stages used in the salt-affected soils study are described in detail: open willow stands (stage III), balsam poplar–alder stands (stage VI), and a mature white spruce stand (stage VIII). There is a general progression of plant species resulting from the modification of the environment by the developing vegetation and changes in soil characteristics. Life history and stochastic events are important in the early stages of succession, and biological controls such as facilitation and competition become more important in middle and late stages of succession.

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Paleoecology of late-glacial terrestrial deposits with in situ conifers from the submerged continental shelf of western Canada

Quaternary Research ◽

10.1016/s0033-5894(03)00083-8 ◽

2003 ◽

Vol 60 (2) ◽

pp. 180-188 ◽

Cited By ~ 40

Author(s):

Terri Lacourse ◽

Rolf W. Mathewes ◽

Daryl W. Fedje

Keyword(s):

Continental Shelf ◽

Pinus Contorta ◽

Late Glacial ◽

Plant Macrofossils ◽

Terrestrial Vegetation ◽

Queen Charlotte Islands ◽

Subaerial Exposure ◽

Late Wisconsinan ◽

Heracleum Lanatum

AbstractExtensive portions of the continental shelf off the coast of British Columbia were subaerially exposed during Late Wisconsinan deglaciation due to lowering of relative sea level by as much as 150 m. Paleoecological analyses were conducted at two sites on the emergent continental shelf where terrestrial surfaces with in situ conifers are preserved. The woody plant remains confirm that, during the latest period of subaerial exposure, terrestrial vegetation was established on the continental shelf. Microscopic identification of fossil wood, and analyses of pollen and plant macrofossils from the associated paleosols and overlying shallow pond sediments indicate that productive Pinus contorta-dominated communities with abundant Alnus crispa and ferns grew on the shelf adjacent to and on the Queen Charlotte Islands around 12,200 14C yr B.P. Dwarf shrubs including Salix and Empetrum, and herbaceous plants such as Heracleum lanatum and Hippuris vulgaris, were also important components of the shelf vegetation. Near northern Vancouver Island, mixed coniferous forests dominated by Pinus contorta with Picea, Tsuga spp., Alnus spp., and ferns occupied the shelf at 10,500 14C yr B.P.

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CO2 stimulation and response mechanisms vary with light supply in boreal conifers

Journal of Plant Ecology ◽

10.1093/jpe/rtaa086 ◽

2020 ◽

Author(s):

Qing-Lai Dang ◽

Jacob Marfo ◽

Fengguo Du ◽

Rongzhou Man ◽

Sahari Inoue

Keyword(s):

Elevated Co2 ◽

Picea Glauca ◽

Boreal Forests ◽

Black Spruce ◽

Net Photosynthesis ◽

Growing Season ◽

White Spruce ◽

Light Supply ◽

Ecophysiological Responses ◽

Light Effects

Abstract Aims Black spruce (Picea mariana [Mill.] B.S.P.) and white spruce (Picea glauca [Moench] Voss.) are congeneric species. Both are moderately shade tolerant and widely distributed across North American boreal forests. Methods To understand light effects on their ecophysiological responses to elevated [CO2], 1-year old seedlings were exposed to 360 and 720 µmol mol -1 [CO2] at three light conditions (100, 50 and 30% of full light in the greenhouse). Foliar gas exchanges were measured in the mid- and late-growing season. Important Findings Elevated [CO2] increased net photosynthesis (Pn) and photosynthetic water use efficiency, but it reduced stomatal conductance and transpiration. The stimulation of photosynthesis by CO2 was greatest at 50% light and smallest at 100%. Photosynthesis, maximum carboxylation rate (Vcmax) and light saturated rate of electron transport (Jmax) all decreased with decreasing light. Elevated [CO2] significantly reduced Vcmax across all light treatments and both species in mid-growing season. However, the effect of elevated [CO2] became insignificant at 30% light later in the growing season, with the response being greater in black spruce than in white spruce. Elevated [CO2] also reduced Jmax in white spruce in both measurements while the effect became insignificant at 30% light later in the growing season. However, the effect on black spruce varied with time. Elevated [CO2] reduced Jmax in black spruce in mid-growing season in all light treatments and the effect became insignificant at 30% light later in the growing season, while it increased Jmax later in the season at 100% and 50% light. These results suggest that both species benefited from elevated CO2, and that the responses varied with light supply, such that the response was primarily physiological at 100% and 50% light, while it was primarily morphological at 30% light.

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The Tunica Hills, Louisiana-Mississippi: Late Glacial Locality for Spruce and Deciduous Forest Species

Quaternary Research ◽

10.1016/0033-5894(77)90038-2 ◽

1977 ◽

Vol 7 (2) ◽

pp. 218-237 ◽

Cited By ~ 50

Author(s):

Paul A. Delcourt ◽

Hazel R. Delcourt

Keyword(s):

Plant Species ◽

Mississippi River ◽

White Spruce ◽

Late Glacial ◽

Plant Macrofossils ◽

Lateral Migration ◽

Forest Species ◽

Local Cooling ◽

Boreal Species ◽

Mesophytic Forest

Reinvestigation of Quaternary sediments in West Feliciana Parish, southeastern Louisiana, and adjacent Wilkinson County, southwestern Mississippi, has resulted in revision of previous terrace stratigraphy of this portion of the Gulf Coastal Plain. Plant-macrofossil and pollen assemblages incorporated in fluviatile terrace deposits in the study area are reexamined in light of the current stratigraphic understanding. Macrofossils identified as white spruce (Picea glauca), tamarack (Larix laricina), and northern white cedar (Thuja occidentalis), recovered from these terrace deposits along with fossil remains of distinctly southern plant species, were initially interpreted as the result of dynamic intermixing of aggressive boreal species within a southern forest during the early Wisconsin (Brown, 1938). Failure to distinguish chronologically separate fossiliferous deposits resulted in the conceptual “mixing” of northern and southern plant species which came from two distinct fluviatile terrace sequences. Terrace 2 is now believed to be a fluviatile and coastwise depositional terrace of Sangamon Interglacial age; deposits of terrace 2 contain a distinctly warm-temperate plant assemblage. Fluviatile terrace 1 dates from 12,740 ± 300 to 3457 ± 366 BP and is now considered to be related to late glacial and Holocene aggradation and lateral migration of the Mississippi River (the local base level for streams in the study area); basal portions of terrace 1 contain fossils of white spruce, tamarack, and many plant species today characteristic of the cool-temperate Mixed Mesophytic Forest Association. Terrace 1 fossil deposits occur in fluviatile terraces along tributary streams of the Mississippi River at elevations 15 to 30 m above the maximum recorded historic flood stage of the Mississippi River. The plant macrofossils represent remains of species that grew at or very near the site of deposition; they were not “rafted in” by floodwaters of the Mississippi River. We present quantitative data for plant macrofossils and pollen that support our hypothesis that at least local cooling along the Blufflands of Mississippi and Louisiana promoted southward migrations of mixed mesophytic forest species and certain boreal species along this major pathway during late Wisconsin continental glaciation.

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