scholarly journals Long‐term demographic decline and late glacial divergence in a Californian paleoendemic: Sequoiadendron giganteum (giant sequoia)

2016 ◽  
Vol 6 (10) ◽  
pp. 3342-3355 ◽  
Author(s):  
Richard S. Dodd ◽  
Rainbow DeSilva
Keyword(s):  
Late Glacial ◽  
Giant Sequoia ◽  
Sequoiadendron Giganteum

scholarly journals An evaluation of climate, crustal movement and base level controls on the Middle-Late Pleistocene development of the River Severn, U.K.

2002 ◽  
Vol 81 (3-4) ◽  
pp. 329-338 ◽  
Author(s):  
D. Maddy
Keyword(s):  
Sea Level ◽  
Late Glacial ◽  
High Energy ◽  
Cold Climate ◽  
Faunal Remains ◽  
Sea Level Changes ◽  
Climate Conditions ◽  
Oxygen Isotope Stage ◽  
Base Level

AbstractThe Pleistocene development of the lower Severn valley is recorded in the fluvial sediments of the Mathon and Severn Valley Formations and their relationship to the glacigenic Wolston (Oxygen Isotope Stage 12), Ridgacre (OIS 6) and Stockport (OIS 2) Formations. The most complete stratigraphical record is that of the Severn Valley Formation, which post-dates the Anglian Wolston Formation and comprises a flight of river terraces, the highest of which is c.50 m above the present river. The terrace staircase indicates that the Severn has progressively incised its valley during the post-Anglian period. The terrace sediments are predominantly composed of fluvially deposited sands and gravels, largely the result of deposition in high-energy rivers under cold-climate conditions. Occasionally towards the base of these terrace deposits low-energy fluvial facies are preserved which contain faunal remains and yield geochronology which support their correlation with interglacial conditions. This simple stratigraphy supports a climate-driven model for the timing of terrace aggradation and incision, with the incision mode at its most effective during the cold-warm transitions and the aggradational mode at its most effective during warm-cold climate transitions. The chronology of terrace aggradation in the lower Severn seems to correspond with the Milankovitch lOOka climate cycles. The timing of incision events suggests that base level (eustatic sea-level) changes do not play a significant role i.e. incision occurs as sea-level is rising.Although climate change is significant in governing the timing of incision, the long-term incision of the River Severn appears to be driven by crustal uplift. A long-term incision rate of 0.15 m ka1, calculated using the base of the terrace deposits, is believed to closely equate with the long-term uplift rate. Superimposed on this long-term uplift are periods of complex terrace sequence development resulting from rapid incision during periods of glacio-isostatic rebound, with large incision events reflecting the rebound adjustment to late glacial stage isostatic depression. However, in no case in the Severn valley has glacial encroachment led to enhanced incision, suggesting that there has been no additional uplift resulting from isostatic compensation for glacial erosion.

Evidence for high-frequency late Glacial to mid-Holocene (16,800 to 5500 cal yr B.P.) climate variability from oxygen isotope values of Lough Inchiquin, Ireland

2006 ◽  
Vol 65 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Aaron F. Diefendorf ◽  
William P. Patterson ◽  
Henry T. Mullins ◽  
Neil Tibert ◽  
Anna Martini
Keyword(s):  
Climate Variability ◽  
High Frequency ◽  
Younger Dryas ◽  
Late Glacial ◽  
Climate Anomaly ◽  
Climate Conditions ◽  
Late Glacial Period ◽  
High Frequency Variability ◽  
Western Ireland

AbstractA 7.6-m core recovered from Lough Inchiquin, western Ireland provides evidence for rapid and long-term climate change from the Late Glacial period to the Mid-Holocene. We determined percentage of carbonate, total organic matter, mineralogy, and δ18Ocalcite values to provide the first high-resolution record of climate variability for this period in Ireland. Following deglaciation, rapid climate amelioration preceded large increases in GISP2 δ18Oice values by ∼2300 yr. The Oldest Dryas (15,100 to 14,500 cal yr B.P.) Late Glacial event is documented in this record as a decrease in δ18Ocalcite values. Brief warming at ∼12,700 cal yr B.P. was followed by characteristic Younger Dryas cold and dry climate conditions. A rapid increase in δ18Ocalcite values at ∼10,500 cal yr B.P. marked the onset of Boreal warming in western Ireland. The 8200 cal yr B.P. event is represented by a brief cooling in our record. Prior to general warming, a larger and previously undescribed climate anomaly between 7300 and 6700 cal yr B.P. is characterized by low δ18Ocalcite values with high-frequency variability.

scholarly journals Greenhouse gas production in degrading ice-rich permafrost deposits in northeast Siberia

2018 ◽  
Author(s):  
Josefine Walz ◽  
Christian Knoblauch ◽  
Ronja Tigges ◽  
Thomas Opel ◽  
Lutz Schirrmeister ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Greenhouse Gas ◽  
Late Glacial ◽  
Gas Production ◽  
Depositional Environments ◽  
Co2 Production ◽  
Glacial Deposits ◽  
Ch4 Production ◽  
Carbon Dioxide Co2

Abstract. Permafrost deposits have been a sink for atmospheric carbon for millennia. Thaw-erosional processes, however, can lead to rapid degradation of ice-rich permafrost and the release of substantial amounts of organic carbon (OC). The amount of the OC stored in these deposits and their potential to be microbially decomposed to the greenhouse gases carbon dioxide (CO2) and methane (CH4) depends on climatic and environmental conditions during deposition and the decomposition history before incorporation into the permafrost. Here, we examine potential greenhouse gas production in degrading ice-rich permafrost deposits from three locations in the northeast Siberian Laptev Sea region. The deposits span a period of about 55 kyr and include deposits from the last glacial and Holocene interglacial periods. Samples from all three locations were aerobically and anaerobically incubated for 134 days at 4 °C. Greenhouse gas production was generally higher in glacial than Holocene deposits. In permafrost deposits from the Holocene and the late glacial transition, only 0.1–4.0 % of the initially available OC could be decomposed to CO2, while 0.2–6.1 % could be decomposed in glacial deposits. Within the glacial deposits from the Kargin interstadial period (Marine Isotope Stage 3), local depositional environments, especially soil moisture, also affected the preservation of OC. Sediments deposited under wet conditions contained more labile OC and thus produced more greenhouse gases than sediments deposited under drier conditions. To assess the long-term production potentials, deposits from two locations were incubated for a total of 785 days. However, more than 50 % of the aerobically produced and more than 80 % of anaerobically produced CO2 after 785 days of incubation were already produced within the first 134 days, highlighting the quantitative importance of the slowly decomposing OC pool in permafrost. CH4 production was generally observed in active layer samples but only sporadically in permafrost samples and was several orders of magnitude smaller than CO2 production.

scholarly journals Climate evolution during the Pleniglacial and Late Glacial as recorded in quartz grain morphoscopy of fluvial to aeolian successions of the European Sand Belt

Geologos ◽  
2015 ◽  
Vol 21 (2) ◽  
pp. 89-103 ◽  
Author(s):  
Barbara Woronko ◽  
Paweł Zieliński ◽  
Robert Jan Sokołowski
Keyword(s):  
Late Glacial ◽  
Sediment Supply ◽  
Alluvial Fans ◽  
Fluvial Sediments ◽  
Aeolian Processes ◽  
River Terraces ◽  
Climate Evolution ◽  
Quartz Grains ◽  
The Last Glacial

Abstract We present results of research into fluvial to aeolian successions at four sites in the foreland of the Last Glacial Maximum, i.e., the central part of the “European Sand Belt”. These sites include dune fields on higher-lying river terraces and alluvial fans. Sediments were subjected to detailed lithofacies analyses and sampling for morphoscopic assessment of quartz grains. Based on these results, three units were identified in the sedimentary succession: fluvial, fluvio-aeolian and aeolian. Material with traces of aeolian origin predominate in these sediments and this enabled conclusions on the activity of aeolian processes during the Pleniglacial and Late Glacial, and the source of sediment supply to be drawn. Aeolian processes played a major role in the deposition of the lower portions of the fluvial and fluvio-aeolian units. Aeolian material in the fluvial unit stems from aeolian accumulation of fluvial sediments within the valley as well as particles transported by wind from beyond the valley. The fluvio-aeolian unit is composed mainly of fluvial sediments that were subject to multiple redeposition, and long-term, intensive processing in an aeolian environment. In spite of the asynchronous onset of deposition of the fluvio-aeolian unit, it is characterised by the greatest homogeneity of structural and textural characteristics. Although the aeolian unit was laid down simultaneously, it is typified by the widest range of variation in quartz morphoscopic traits. It reflects local factors, mainly the origin of the source material, rather than climate. The duration of dune-formation processes was too short to be reflected in the morphoscopy of quartz grains.

scholarly journals Long-term taper and growth reductions following pruning intensity treatments in giant sequoia (Sequoiadendron giganteum)

2019 ◽  
Vol 49 (10) ◽  
pp. 1189-1197
Author(s):  
Robert A. York
Keyword(s):  
Stem Growth ◽  
Repeated Measurements ◽  
Similar Degree ◽  
Crown Length ◽  
Stem Taper ◽  
Giant Sequoia ◽  
Sequoiadendron Giganteum ◽  
The Cost ◽  
High Degree ◽  
Pruning Intensity

A high degree of stem taper limits the potential value of giant sequoia (Sequoiadendron giganteum (Lindl.) J. Buchholz) when grown for timber. I measured the effects of pruning to different height targets (0, 2.0, 3.5, and 5.5 m), resulting in the removal of 25%–85% of crown length, on the growth of 360 S. giganteum trees over 17 years. Height growth and growth of diameter at breast height were both negatively related to pruning intensity to a similar degree. Within the 17 years following pruning, repeated measurements of stem growth at different heights above the ground revealed that radial stem growth reductions were localized on the stems from which branches were removed. The higher up that trees were pruned, the more that stem radial growth was reduced compared with control trees, with the greatest reductions occurring at stem bases. The effects of pruning decreased over time, but there were still significant differences after 17 years. Girard form class was only influenced by the most intense pruning at a stem height of 5.5 m. A benefit of pruning was reduced taper, but this came at the cost of reduced stem growth. Pruning in S. giganteum must be done carefully with respect to its timing, intensity, and interactions with other management treatments on young stands.

scholarly journals The effect of the Sequoiadendron giganteum (Lindl.) Buchholz cone crystals on germination

2019 ◽  
Vol 65 (No. 6) ◽  
pp. 203-208
Author(s):  
Hana Prknová
Keyword(s):  
Norway Spruce ◽  
Scots Pine ◽  
Inhibitory Effect ◽  
Water Soluble ◽  
Compelling Evidence ◽  
European Larch ◽  
Ecological Optimum ◽  
Giant Sequoia ◽  
Sequoiadendron Giganteum ◽  
Representative Samples

The cones of the giant sequoia contain red, water-soluble crystalline substances known as cone crystals. The inhibitory effect of this extracted material on Norway spruce, Scots pine and European larch germination was newly examined. Sown seed representative samples without and with added cone crystals were compared after their incubation in the same appropriate conditions. All these cases have brought compelling evidence that cone crystals totally inhibit germination. However, the chemically inhibited seeds being rinsed afterwards germinated very well. This switch effect caused by the cone crystals of the three above-mentioned conifers proved to be a nonspecific tool. Seeds of the giant sequoia, naturally affected by the cone crystals, were sown as rinsed and non-rinsed samples. Both the samples, grown on a wet peat substrate in appropriate conditions for 16 weeks, exhibited an equal, yet very low viability of 1.3% at the same time. This low number, fixed in seeds of the tree being far from the ecological optimum, does not allow any disputation with other authors.

TRACHEID AND PIT ANATOMY VARY IN TANDEM IN A TALL SEQUOIADENDRON GIGANTEUM TREE

IAWA Journal ◽  
2016 ◽  
Vol 37 (2) ◽  
pp. 172-185 ◽  
Author(s):  
Martina Lazzarin ◽  
Alan Crivellaro ◽  
Cameron B. Williams ◽  
Todd E. Dawson ◽  
Giacomo Mozzi ◽  
...  
Keyword(s):  
Hydraulic Resistance ◽  
General Pattern ◽  
Scaling Exponent ◽  
Membrane Area ◽  
Tracheid Length ◽  
Bordered Pits ◽  
Giant Sequoia ◽  
Sequoiadendron Giganteum ◽  
Side Walls ◽  
Flow Through

Across land plants there is a general pattern of xylem conduit diameters widening towards the stem base thus reducing the accumulation of hydraulic resistance as plants grow taller.In conifers, xylem conduits consist of cells with closed end-walls and water must flow through bordered pits imbedded in the side walls. As a consequence both cell size, which determines the numbers of walls that the conductive stream of water must cross, as well as the characteristics of the pits themselves, crucially affect total hydraulic resistance. Because both conduit size and pit features influence hydraulic resistance in tandem, we hypothesized that features of both should vary predictably with one another. To test this prediction we sampled a single tall (94.8 m) Sequoiadendron giganteum tree (giant sequoia), collecting wood samples from the most recent annual ring progressively downwards from the tree top to the base. We measured tracheid diameter and length, number of pits per tracheid, and the areas of pit apertures, tori, and margos. Tracheid diameter widened from treetop to base following a power law with an exponent (tracheid diameterstem length slope) of approximately 0.20. A similar scaling exponent was found between tracheid length and distance from tree top. Additionally, pit aperture, torus, and margo areas all increased (again with a power of ~0.20) with distance from tree top, paralleling the observed variation in tracheid diameter and length. Pit density scaled isometrically with tracheid length. Within individual tracheids, total permeable area of pits, measured as the sum of the margo areas, scaled isometrically with lumen area. Given that pores of the margo membrane are believed to increase in parallel with membrane area, from a strictly anatomical perspective, our results support the interpretation that pit resistance remains a relatively constant fraction of total resistance along the hydraulic pathway.

Giant Sequoia (Sequoiadendron giganteum) Regeneration in Experimental Canopy Gaps

2011 ◽  
Vol 19 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Robert A. York ◽  
John J. Battles ◽  
Anne K. Eschtruth ◽  
Frieder G. Schurr
Keyword(s):  
Canopy Gaps ◽  
Giant Sequoia ◽  
Sequoiadendron Giganteum
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