Subfossil Scots Pine Research Articles

‘Pine Decline or pine declines?’ Analysis and Interpretation of Bog-Pines from Wem Moss, Shropshire, UK

A dendrochronological investigation was undertaken on subfossil Scots pine (Pinus sylvestris L.) stumps following their discovery during conservation management at Wem Moss, a small (28 ha) former raised mire in Shropshire, UK. Two ring-width chronologies were constructed from 14 of the 17 trees sampled spanning 198 and 208 years, respectively. Whilst dendrochronological dating was not possible, radiocarbon assays provided an estimated age for this mire-rooting woodland of between 3015 and 2505 years cal. BCE, coinciding with the age traditionally associated with the widespread mortality of pine trees throughout much of the UK and Ireland, often referred to as the Pine Decline (ca. 4000 radiocarbon years BP). Placed in a wider geographical context, the Wem Moss pines are located within the lowland Meres and Mosses region, where previous studies on subfossil pine have demonstrated protracted declines in mire-rooting trees. These have included tree mortality significantly post-dating the Pine Decline, especially at larger peatland sites that exceed 5 km2. Such macrofossil evidence for the presence of Scots pine into the late Holocene is supported by continuous Pinus pollen representation at peatland sites in the Welsh Marches (English–Welsh border), suggesting the possible survival of native Scots pine trees in this area up to the present day. The investigation of Wem Moss bog pines and their wider geographical context highlights the incomplete and patchy nature of palaeo-vegetational records and also the need for future genetic research on living Scots pine in possible refugial areas in Britain and Ireland.

Subfossil Scots Pine (Pinus sylvestris L.) Wood from Northern Finland—Physical, Mechanical, and Chemical Properties and Suitability for Specialty Products

The physical, mechanical, and chemical properties of both stem wood and knot wood were investigated from two subfossil Scots pine (Pinus sylvestris L.) trunks retrieved from a lake in Finnish Lapland, dated to 404–486 CE and to 1318–1444 CE. Both the stem wood and the knot wood of the younger trunk had higher moisture content, lower density, and lower strength properties in comparison to the older trunk. The ash content of the stem wood of the younger trunk was lower, but the ash content of the knot wood was higher than that of the older trunk. Due to the degradation that occurred over time, all the values of physical and mechanical properties were lower compared to typical values of recently grown Scots pine wood. The chemical composition of both stem wood samples was close to the composition of the recently grown wood, and the only exception was the small decrease of the cellulose and hemicellulose in the subfossil samples. The bulk extractives were well-preserved, but terpenes and fatty acids underwent transformation, resulting in more stable compounds. The SWOT analysis (strengths, weaknesses, opportunities, and threats) showed pros and cons for the productization of subfossil wood, with the branding value of an ancient material being the potential enabler in developing commercial niche uses.

Sorption isotherms of waterlogged subfossil Scots pine wood impregnated with a lactitol and trehalose mixture

AbstractA waterlogged subfossil Scots pine wood, 12 500-years-old, was impregnated with a mixture of lactitol and trehalose as well as with polyethylene glycol (PEG) mixtures, respectively, and the sorption properties of the impregnated samples were determined. All the impregnated wood samples were freeze-dried. The sorption isotherms were parameterized with the Guggenheim-Anderson-deBoer (GAB) and Generalized D’Arcy and Watt (GDW) models. Better hygroscopic properties were found for wood impregnated with the lactitol and trehalose mixture as compared to the PEG treatments. An anomalous increase of equilibrium moisture content (EMC) was found for PEG treated wood at a high relative humidity (RH) as compared to untreated wood at RH<80%. The lactitol and trehalose mixture significantly reduced this effect due to the decreased sorption of polymolecular water. Another positive effect of the alternative method is the ca. 50% reduction of the sorption hysteresis as compared to untreated wood. Moreover, the hysteresis was also much lower in the case of high RH as compared to PEG treated wood. The alternative treatment is also effective in terms of the dimensional stabilization of decayed wood.

Study on dimensional stabilization of 12,500-year-old waterlogged subfossil Scots pine wood from the Koźmin Las site, Poland

Abstract The study examines the efficiency of selected conservation treatments proposed for dimensional stabilization of 12,500-year-old waterlogged subfossil Scots pine (Pinus sylvestris L.) tree trunks found at the Koźmin Las site, Poland. The research was done on 198 samples drawn from various parts of the same trunk. Experimental material was characterized on the basis of annual ring width, percentage of latewood, maximum moisture content, density at maximum moisture content, basic density, and wood porosity. Waterlogged wood samples were pre-treated with aqueous solutions of polyethylene glycol (PEG) 300, mixtures of PEG 300 and PEG 4000, a mixture of lactitol and trehalose or a mixture of mannitol and trehalose (nine variants of impregnation) and then freeze-dried or air-dried. Dimensional changes in the wood samples were measured after seasoning to reach equilibrium moisture content at 50% relative humidity and 20 °C. In the majority of the tested conservation treatments, tangential and radial shrinkages or tangential and radial swelling of wood did not exceed 1%. However, differences in dimensional changes depended on the conservation method used and sampling location. Regardless of the state of wood preservation and macroscopic structure features, the best dimensional stability, evaluated on the basis of average anti-shrink efficiency indices, was observed in wood pre-treated with aqueous solutions of 10% PEG 300 + 5% PEG 4000, 10% PEG 300 + 10% PEG 4000 or 10% lactitol/trehalose mixture, and then freeze-dried.

Recent advances in long-term climate and moisture reconstructions from the Baltic region: Exploring the potential for a new multi-millennial tree-ring chronology

This study presents the first results from an ongoing initiative to develop a multi-millennial Baltic tree-ring width (TRW) chronology consisting of 12 floating records from subfossil Scots pines (Pinus sylvestris L.) extracted from three Lithuanian peat-mining areas. The floating series have been complemented with absolutely dated TRW chronologies which were obtained from living trees growing in unmanaged and unexploited peatland areas adjacent to each of the above study sites. The subfossil material has been dated by radiocarbon and shows a temporal spread over the last 6000 years, with assemblages of trees during the Holocene Thermal Maximum (HTM; 8000-4000 BP) and the onset of the Medieval Warm Period (MWP, AD 900–1350). Annual tree growth and sample replication of peatland pines reflect moisture variations and long-term climate variability. The importance of extending the TRW chronologies should not therefore be underestimated as (1) climate records of comparable length and resolution do not exist for the Baltic region, but also as (2) a result of a widespread lack of detailed moisture proxies spanning several millennia. Our data clearly show that a 6000-yr, continuous pine chronology from the Baltic region is a realistic objective, and would doubtlessly fill a major geographic gap in an ecologically sensitive region located at the interface between the temperate and boreal vegetation zones.

South Swedish bog pines as indicators of Mid-Holocene climate variability

Dendroclimatic investigations of subfossil Scots pine (Pinus sylvestris) from two raised bogs in southern Sweden yielded a continuous floating 1492-year long tree-ring record. By cross-dating with bog-pine chronologies from Lower Saxony, Germany, the South Swedish record was assigned an absolute age of 5219–3728 BC. The cross-match between ring-width chronologies from these two regions, separated by 500–700km, is remarkably strong and the correlation positive, which indicates that large-scale climate dynamics had a significant impact on the growth of bog pines during the Holocene Thermal Maximum (HTM) when bog-pine distribution reached a maximum in both regions. However, local population dynamics were also influenced by peatland ontogeny and competition, as shown by differences in replication and mean tree age between the Swedish and German records. Comparisons with chronologies developed from modern bog pines in southern Sweden indicate that more coherent climate was controlling pine growth on natural peatlands during warm periods in the past. This study demonstrates the usefulness of Swedish subfossil bog-pine material as a climate proxy, with particular potential for decadal- to centennial-scale reconstructions of humidity fluctuations.

Mid-Holocene warming in the northwest Kola Peninsula, Russia: northern pine-limit movement and stable isotope evidence

A set of 40 subfossil Scots pines (Pinus sylvestris L.) was sampled in small lakes beyond the modernpine limit in the northwest Kola Peninsula, Russia. Radiocarbon dating suggests that the pine expanded north of its present-day limit between 7000 and 3500yr BP. The most extensive occurrence of pine forests was reconstructed between 6250 and 5750 yr BP. Numerous samples collected from trunks and stubs in situ clearly indicate lower lake levels between 6200 and 4400 yr BP. Living and 14C dated subfossil pine samples were analysed for the mean carbon, oxygen and hydrogen stable isotope composition of their wood cellulose. The mean δ13C, δ18O and δ2H values of the wood samples from the mid-Holocene time are C. 1.1%, 0.9% and lock, respectively - more positive than those of living trees in this region. These results suggest that the mid-Holocene climate in the region was warmer and drier than nowadays. The data agree with previous palynological, macrofossil and limnological studies from northernmost Fennoscandia. During the late-Holocene climatic deterioration after c. 3500 yr BP, the decline of the northern pine limit was synchronous with other parts of northern Eurasia. Comparison with dated pine series from the north-central Kola Peninsula and Finnish Lapland suggests that the decline of the northernmost pine limit in the eastern part of the area may have occurred somewhat earlier than in the western part.

Low-frequency summer temperature variation in central Sweden since the tenth century inferred from tree rings

Living and subfossil Scots pine ( Pinus sylvestris L.) sampled close to the present tree-line in the central Scandinavian Mountains were used to build a continuous 1091-year long tree-ring-width chronology, spanning from ad 909 to 1998. Summer temperatures of the growth year had the highest influence on annual growth. The Håckren chronology represent a record of summer temperatures, where periods of low growth and poor regeneration of pine represent unfavourable climate conditions. Low growth was encountered in the mid-twelfth, thirteenth, late sixteenth, early seventeenth and late eighteenth centuries. Periods of high growth (high regeneration rate and above-average growth), indicating high summer temperatures, were recognized in the mid-tenth to late eleventh, mid-fourteenth, mid-seventeenth and twentieth centuries. As the chronology is well correlated with other high-latitude proxy data from Fennoscandia, as well as the Northern Hemisphere, we argue that the Håckren chronology is a valid proxy-data record of regional summer temperatures.

High-resolution climate signals in the Bølling–Allerød Interstadial (Greenland Interstadial 1) as reflected in European tree-ring chronologies compared to marine varves and ice-core records

Lateglacial and Holocene tree-ring chronologies are unique archives, which provide various information on past environments on a true annual time scale. Changes in ring-width can be related to past climate anomalies and dendrodated wood provides an ideal source for radiocarbon calibration. We present a 1051 year tree-ring chronology from the Late Glacial, built from subfossil Scots pines (Pinus sylvestris) that grew in different regions of Central and Southern Europe. Through a series of high-precision radiocarbon measurements we obtained a floating radiocarbon chronology, which allowed accurate wiggle-matching to the INTCAL98 calibration curve. The trees show a coherent pattern in ring-width variations throughout Central Europe, and extending into the Mediterranean, which indicates a strong external climatic factor, most probably temperature during the growing season. We identified major growth events, which appear synchronous with events seen in isotopic and tracer signals in the Greenland ice cores and with changes in the strength of upwelling in the Cariaco Basin.

Using fire scars and growth release in subfossil Scots pine to reconstruct prehistoric fires

Fire scars indicating low- to moderate-intensity fires on peat deposits have been sampled from subfossil Scots pine ( Pinus sylvestris L.) at sites in England, Wales and south-west Ireland. Analysis of ring-width responses to one fire event in 2800 BC illustrates its rejuvenating effect on Pinus sylvestris woodland, supporting a growing body of modern and palaeoecological data that illustrates the regenerative role played by fire in persistence of Pinus sylvestris woodland. Both the scale and timing of these fires suggest that infrequent low- to moderate-intensity fires are sufficient to stimulate Pinus sylvestris growth. This effect is shown by average increases in ring-width following the fire of between 0.62 and 1.16 mm in non-scarred trees and between 0.92 and 2.74 mm in fire-scarred individuals. Growth release in non-scarred trees may prove to be a more reliable method of detecting fire than using the relatively rare fire scars alone. Radii at time of scarring varied between 1.85 and 11.2 cm, much smaller than is predicted to survive from modern studies.

Holocene humidity changes in northern Finnish Lapland inferred from lake sediments and submerged Scots pines dated by tree-rings

Conclusive evidence for a rise in water levels has been found in connection with lake-sediment studies undertaken partly in collaboration with the pine megafossil sampling and dendrochronological work in northern Finnish Lapland. The change in lake-level stands is shown by slow sedimentation rate in the early to mid-Holocene and an increase thereafter. These data indicate a regional rise in water levels during the latter part of the Holocene following a relatively dry period between 8000 and 4000 BP. Synchronous changes, also indicating rising water levels, have been observed in the diatom and cladoceran assemblages of the sediment cores. Subfossil Scots pines (Pinus sylvestris, L.) have been preserved in large quantities in small lakes in Lapland, because in many cases the rising water level has inundated the trunks after death. The position of the subfossil trunks and stumps often indicates that the pines have been growing on dry land at the sides of the lakes in which they are now submerged. Traces of a bark beetle (Tomicus minor, Hart.) have been detected in a few old pine logs found far outside the present distribution area of this insect. A total of 1722 samples of pine subfossils have been collected in the forest-tundra ecotone region of Lapland to build a continuous pine ring-width chronology over 7000 years long. The long chronology is almost finished, but its two parts are still separated by a short discontinuity around 250 bc. An absolutely dated, year-by-year chronology over 2000 years long extends from the present close to that time. The older, over 5000 years long continuous floating chronology is fixed to the timescale by several radiocarbon dates. A total of 1212 samples of pine wood have been dated and assembled within the chronologies by tree-ring cross-matching. These substantial data indicate a gradual retreat of pine tree and forest limits with some marked regional differences during the past 5000 years. According to the preliminary interpretations of the tree-ring data the variability of Holocene summer temperatures has increased towards the present time. Shifts in climatic development leading to cooler and more unstable conditions seem to have occurred in mid-Holocene time, and between 2500 and 2000 BP. The increase in humidity is probably in association with these changes in the high-frequency variability of temperature.

Evidence on climatic variability and prehistoric human activities between 165 B.C. and A.D. 1400 derived from subfossil Scots pines (Pinus sylvestris L.) found in a lake in Utsjoki, northernmost Finland

Evidence on climatic variability and prehistoric human activities between 165 B.C. and A.D. 1400 derived from subfossil Scots pines (Pinus sylvestris L.) found in a lake in Utsjoki, northernmost Finland

Radiocarbon dating of subfossil Scots pine (Pinus sylvestris L.) in the southern Swedish Scandes

Wood samples from above the present‐day pine limit were collected from within a limited area in central Sweden. New dates from an intensively investigated part of that area all fall within the period 8550 ± 110 to 4270 ± 90 14C years B. P. No evidence at present exists to suggest that any drastic change, or fluctuations, in the pine tree‐limit, took place within that period. Some dates support the view that the present‐day altitude of the pine tree‐limit was established during the historic period and perhaps is still declining.