scholarly journals Temperature sensitivity of willow dwarf shrub growth from two distinct High Arctic sites

2018 ◽  
Vol 63 (2) ◽  
pp. 167-181 ◽  
Author(s):  
Agata Buchwal ◽  
Stef Weijers ◽  
Daan Blok ◽  
Bo Elberling
1978 ◽  
Vol 129 ◽  
pp. 1-66
Author(s):  
S Funder

The Holocene stratigraphy in Scoresby Sund is based on climatic change as reflected by fluctuations in fjord and valley glaciers, immigration and extinction of marine molluscs, and the vegetation history recorded in pollen diagrams from five lakes. The histories are dated by C-14, and indirectly by emergence curves showing the patterns of isostatic uplift. From c. 10100-10400 to 9400 yr BP the major fjord glaciers showed oscillatory retreat with abundant moraine formation, the period of the Milne Land Moraines. The vegetation in the ice-free areas was a sparse type of fell field vegetation but with thermophilous elements indicating temperatures similar to the present. From 9400 yr BP the fjord glaciers retreated rapidly in the narrow fjords, the few moraines formed are referred to the Rødefjord stages and indicate topographically conditioned stillstands. At 8000 yr BP the low arctic Betula nana immigrated into the area, and in the period until 5000 yr BP dense dwarf shrub heath grew in areas where it is now absent. In the fjords the subarctic Mytilus edulis and Pecten islandica lived, suggesting a climate warmer than the present. From c. 5000 yr BP the dense dwarf shrub heath began to disappear in the coastal areas, and a 'poor' heath dominated by the high arctic Salix Arctica and Cassiope tetragona expanded. These two species, which are now extremely common, apparently did not grow in the area until c. 6000 yr BP. In lakes in the coastal area minerogenic sedimentation at c. 2800 yr BP, reflecting the general climatic deterioration.


2016 ◽  
Vol 6 (7) ◽  
pp. 2139-2148 ◽  
Author(s):  
Jos M. Milner ◽  
Øystein Varpe ◽  
René Wal ◽  
Brage Bremset Hansen
Keyword(s):  

Author(s):  
Evangeline Fisher

Enhanced precipitation and higher temperatures are expected in the Arctic as the result of future climatic warming. To understand future contributions of high‐arctic ecosystems to the climate system, we need to understand the feedbacks between climate and greenhouse gas production, and how they might vary between plant community types distributed along soil moisture gradients. We incubated intact soil cores in the laboratory to explore the temperature sensitivity of soil greenhouse gas (CO2, CH4, N2O) production across the three main plant community types of Cape Bounty, Nunavut: polar desert, mesic tundra and wet sedge. Two sets of cores (0‐10 cm mineral soil) were incubated in the laboratory at 4, 8, and 12°C for one month. We also measured plant community differences in soil thermal regimes for one year. Mean field temperatures were highest in the polar desert during the summer months, while temperatures in the mesic tundra were lowest during this time. In the winter, soil temperatures were lowest in the polar desert and highest in the wet sedge communities. Initial incubation results demonstrate Q10 values for CO2 production ranging from 2.18 in wet sedge to 8.67 in polar desert soils. We observed a Q10 of 4.03 for CH4 output in mesic tundra soils and a Q10 of 16.42 for N2O output in wet sedge soils. Our results suggest that use of single Q10 values to predict future greenhouse gas emissions from high‐arctic ecosystems would likely underestimate the contribution of these ecosystems to the global climate system in a warmer climate.


2015 ◽  
Vol 10 (4) ◽  
pp. 044008 ◽  
Author(s):  
Daan Blok ◽  
Stef Weijers ◽  
Jeffrey M Welker ◽  
Elisabeth J Cooper ◽  
Anders Michelsen ◽  
...  

The Holocene ◽  
2013 ◽  
Vol 23 (5) ◽  
pp. 721-731 ◽  
Author(s):  
Stef Weijers ◽  
Friederike Wagner-Cremer ◽  
Ute Sass-Klaassen ◽  
Rob Broekman ◽  
Jelte Rozema

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