scholarly journals A climate-driven tree line position model in the White Mountains of California over the past six millennia

2018 ◽  
Vol 45 (5) ◽  
pp. 1067-1076 ◽  
Author(s):  
Jamis M. Bruening ◽  
Andrew G. Bunn ◽  
Matthew W. Salzer
Keyword(s):  
Tree Line ◽  
Line Position ◽  
White Mountains ◽  
The Past

Holocene Climatic Variations Inferred from Treeline Fluctuations in the White Mountains, California

1973 ◽  
Vol 3 (4) ◽  
pp. 632-660 ◽  
Author(s):  
Valmore C. LaMarche
Keyword(s):  
Great Basin ◽  
Warm Season ◽  
White Mountains ◽  
North American Cordillera ◽  
Climatic Variations ◽  
The Past ◽  
The North ◽  
Pinus Longaeva ◽  
Bristlecone Pine ◽  
Dry Conditions

AbstractRemains of dead bristlecone pine (Pinus longaeva Bailey) are found at altitudes up to 150 m above present treeline in the White Mountains. Standing snags and remnants in two study areas were mapped and sampled for dating by tree-ring and radiocarbon methods. The oldest remnants represent trees established more than 7400 y.a. Experimental and empirical evidence indicates that the position of the treeline is closely related to warm-season temperatures, but that precipitation may also be important in at least one of the areas. The upper treeline was at high levels in both areas until after about 2200 B.C., indicating warm-season temperatures about 3.5°F higher than those of the past few hundred years. However, the record is incomplete, relative warmth may have been maintained until at least 1500 B.C. Cooler and wetter conditions are indicated for the period 1500 B.C.-500 B.C., followed by a period of cool but drier climate. A major treeline decline occurred between about A.D. 1100 and A.D. 1500, probably reflecting onset of cold and dry conditions. High reproduction rates and establishment of scattered seedlings at high altitudes within the past 100 yr represents an incipient treeline advance, which reflected a general climatic warming beginning in the mid-19th century that has lasted until recent decades in the western United States. This evidence for climatic variation is broadly consistent with the record of Neoglacial advances in the North American Cordillera, and supports Antevs' concept of a warm “altithermal age” in the Great Basin.

scholarly journals Tree and Shrub Expansion Over the Past 34 Years at the Tree-Line Near Abisko, Sweden

AMBIO ◽  
2011 ◽  
Vol 40 (6) ◽  
pp. 683-692 ◽  
Author(s):  
Sara Rundqvist ◽  
Henrik Hedenås ◽  
Anneli Sandström ◽  
Urban Emanuelsson ◽  
Håkan Eriksson ◽  
...  
Keyword(s):  
Tree Line ◽  
Shrub Expansion ◽  
The Past

scholarly journals Little change in the fir tree-line position on the southeastern Tibetan Plateau after 200 years of warming

2011 ◽  
Vol 190 (3) ◽  
pp. 760-769 ◽  
Author(s):  
Eryuan Liang ◽  
Yafeng Wang ◽  
Dieter Eckstein ◽  
Tianxiang Luo
Keyword(s):  
Tibetan Plateau ◽  
Tree Line ◽  
Line Position ◽  
Southeastern Tibetan Plateau

scholarly journals Ring-widths of the above tree-line shrub Rhododendron reveal the change of minimum winter temperature over the past 211 years in Southwestern China

2016 ◽  
Vol 48 (11-12) ◽  
pp. 3919-3933 ◽  
Author(s):  
Yingfeng Bi ◽  
Jianchu Xu ◽  
Jinchao Yang ◽  
Zongshan Li ◽  
Aster Gebrekirstos ◽  
...  
Keyword(s):  
Winter Temperature ◽  
Southwestern China ◽  
Tree Line ◽  
The Past

scholarly journals Changes in flow of Crosson and Dotson ice shelves, West Antarctica, in response to elevated melt

2018 ◽  
Vol 12 (4) ◽  
pp. 1415-1431 ◽  
Author(s):  
David A. Lilien ◽  
Ian Joughin ◽  
Benjamin Smith ◽  
David E. Shean
Keyword(s):  
Inverse Modeling ◽  
Remotely Sensed ◽  
Significant Loss ◽  
Line Position ◽  
West Antarctica ◽  
Line Flux ◽  
Ice Shelves ◽  
The Past ◽  
Grounding Line

Abstract. Crosson and Dotson ice shelves are two of the most rapidly changing outlets in West Antarctica, displaying both significant thinning and grounding-line retreat in recent decades. We used remotely sensed measurements of velocity and ice geometry to investigate the processes controlling their changes in speed and grounding-line position over the past 20 years. We combined these observations with inverse modeling of the viscosity of the ice shelves to understand how weakening of the shelves affected this speedup. These ice shelves have lost mass continuously since the 1990s, and we find that this loss results from increasing melt beneath both shelves and the increasing speed of Crosson. High melt rates persisted over the period covered by our observations (1996–2014), with the highest rates beneath areas that ungrounded during this time. Grounding-line flux exceeded basin-wide accumulation by about a factor of 2 throughout the study period, consistent with earlier studies, resulting in significant loss of grounded as well as floating ice. The near doubling of Crosson's speed in some areas during this time is likely the result of weakening of its margins and retreat of its grounding line. This speedup contrasts with Dotson, which has maintained its speed despite increasingly high melt rates near its grounding line, likely a result of the sustained competency of the shelf. Our results indicate that changes to melt rates began before 1996 and suggest that observed increases in melt in the 2000s compounded an ongoing retreat of this system. Advection of a channel along Dotson, as well as the grounding-line position of Kohler Glacier, suggests that Dotson experienced a change in flow around the 1970s, which may be the initial cause of its continuing retreat.

Modern and Holocene stomate records of tree-line variations in northwestern Quebec

2004 ◽  
Vol 82 (6) ◽  
pp. 726-734 ◽  
Author(s):  
Ruth Leitner ◽  
K Gajewski
Keyword(s):  
Boreal Forest ◽  
Lake Sediments ◽  
Vegetation History ◽  
Vegetation Distribution ◽  
Tree Line ◽  
Forest Tundra ◽  
The Past ◽  
Pollen Concentrations ◽  
Broad Scale

Conifer stomates in lake sediments from the forest to tundra transition in northwestern Quebec were analysed to reconstruct tree-line history during the past 6000 years. The pollen from these sites had already been analysed. Stomate concentrations in modern sediments generally conform to the vegetation distribution, although stomates were lacking in some forested sites. Results from nine cores on a transect from boreal forest to tundra show broad-scale correspondence between Picea stomate and pollen concentrations. At a smaller scale, however, discrepancies were found, such as the absence of stomates from a forest tundra site. A broad-scale correspondence between pollen and stomate concentrations of Larix was also found, although the low numbers of Larix stomates make interpretation difficult. Neither stomate absence nor presence can unambiguously be used to indicate the absence or presence of trees in the area immediately surrounding the lake.Key words: tree line, palynology, stomate, vegetation history, Picea, Larix.

NOTES ON SOME UNCOMMON CRANE-FLIES FROM THE WHITE MOUNTAINS, NEW HAMPSHIRE

1934 ◽  
Vol 66 (5) ◽  
pp. 116-118
Author(s):  
Charles P. Alexander
Keyword(s):  
New England ◽  
New Hampshire ◽  
Nominal Species ◽  
White Mountains ◽  
The Past ◽  
Crane Flies

During the past decade a considerable amount of work has been done on collecting and studying the crane-flies, Tipulidae, of New England. Johnson's basic list of the Diptera of this area (List of the Diptera or Two-Winged Flies. Occas. Papers Boston Soc. Nat. Hist., VII; 1925) recorded 264 nominal species, of which seven have been removed as being synonyms or as being based on mis-determinations. In the intervening years, 73 additions have been made to this list, bringing the corrected total to date to 330 species.

scholarly journals Foliar Endophytic Fungi from the Endangered Eastern Mountain Avens (Geum peckii, Rosaceae) in Canada

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1026
Author(s):  
Sarah J. Adams ◽  
Brent M. Robicheau ◽  
Diane LaRue ◽  
Robin D. Browne ◽  
Allison K. Walker
Keyword(s):  
Human Impact ◽  
Habitat Degradation ◽  
Leaf Tissue ◽  
Fungal Communities ◽  
White Mountains ◽  
Perennial Plant ◽  
The Past ◽  
Significant Step ◽  
Rare And Endangered ◽  
Tissue Differences

Eastern Mountain Avens (Geum peckii Pursh, Rosaceae) is a globally rare and endangered perennial plant found only at two coastal bogs within Digby County (Nova Scotia, Canada) and at several alpine sites in the White Mountains of New Hampshire (USA). In Canada, the G. peckii population has declined over the past forty years due in part to habitat degradation. We investigated the culturable foliar fungi present in G. peckii leaves at five locations with varying degrees of human impact within this plant species’ Canadian range. Fungal identifications were made using ITS rDNA barcoding of axenic fungal cultures isolated from leaf tissue. Differences in foliar fungal communities among sites were documented, with a predominance of Gnomoniaceae (Class: Sordariomycetes, Phylum: Ascomycota). Habitats with more human impact showed lower endophytic diversities (10–16 species) compared to the pristine habitat (27 species). Intriguingly, several fungi may represent previously unknown taxa. Our work represents a significant step towards understanding G. peckii’s mycobiome and provides relevant data to inform conservation of this rare and endangered plant.

scholarly journals A study on phenological traits of Abies pindrow (Royle) Spach. in the different sites of Garhwal Himalayas, India

2018 ◽  
Vol 10 (1) ◽  
pp. 178-184
Author(s):  
Haseeb U. R. Masoodi ◽  
Dipika Rana ◽  
Manisha Thapliyal ◽  
V. R. R. Singh
Keyword(s):  
Seed Dispersal ◽  
Life History Trait ◽  
Tree Line ◽  
Phenological Data ◽  
Garhwal Himalayas ◽  
Mountainous Regions ◽  
The Past ◽  
Leaf Emergence ◽  
Abies Pindrow ◽  
Important Life History Trait

Phenology, the timing of various events in a species life cycle, is an important life history trait for both plants and animals. Dharali site situated in the highest altitudinal range i.e. 2800-3300 m above msl and showed the initiation of all the phenological characteristics i.e. leaf fall, leaf emergence, appearance of male and female strobili, pollination, cone maturation and seed dispersal in advance as compared to all the other sites. The comparison of the two years phenological data in all the sites (Mundali, Bhukki, Dheoban, Dharali) showed that in the year 2013 early leaf emergence, prolonged cone maturity and early seed dispersal were observed. Rise in temperature and change in climate in mountainous regions has caused the tree line to advance to higher elevations as temperatures have increased over the past few decades. In addition to changing their spatial distributions, plants are also chang-ing their temporal niches.

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