Bog Forest Research Articles

Evolution and radiation effects of the extreme smoke pollution over the european part of Russia in the summer of 2010

Using aerospace monitoring data we performedspatiotemporal analysis of the evolution of smokeaerosol during the period of forest and peat bog fires onthe European territory of Russia (ETR) in the summerof 2010. It is shown that the spatial structure of theETR smoke pollution and its temporal variations wereclosely related to the processes of largescale atmospheric dynamics. In the period from August 5 toAugust 9 the region of maximum smoke pollutionmade a complete clockwise rotation around Moscowremaining at a distance of 200–650 km from the megacity, which prevented even a greater smoke pollutionof Moscow (compared with the pollution observedduring these days). Statistical characteristics of variations in the aerosol optical depth (AOD, ) at the wavelength of 0.55 m (0.55) over the ETR during the wildfires are presented. The mass content of smoke aerosolin the atmospheric column is evaluated as well. We alsoestimated regional mean shortwave radiative forcing ofthe smoke aerosol at the top and at the bottom of theatmosphere. The distributions of the aerosol radiativeforcing (ARF) over the ETR during the fires are presented and their significant spatial inhomogeneitiesare revealed. MODIS AOD data are validated by comparison with AOD data obtained at the AERONETstation Zvenigorod.A spacious and longliving blocking anticyclonethat settled over the ETR in the summer of 2010 [1]radically changed the thermal and hydrologicalregimes of the region [2]. A long drought facilitatedthe appearance and spreading of the forest and peatbog fires, which led to strong aerosol and gas pollutionof the atmosphere in the region that lasted many days[3–6]. The high concentration of smoke aerosol in theair caused strong changes in the radiation regime ofthe atmosphere [7].Unlike the groundbased data, the satellite AODdata along with the estimates of the local smoke loading allow to study the geographical distribution of thesmoke aerosol and its time evolution, obtain estimatesof the spatially distributed (regional) radiative effectsof the smoke, and also retrieve the spatial pattern ofthe ARF. This information is needed for correct estimates of aerosol particle emission during the fires,solution of various climatic problems, and testing ofchemical transport models. In this work, we use thesatellite AOD observations from the MODIS instruments [8, 9] to study the spatiotemporal evolution ofthe AOD and shortwave radiation forcing of the smokeaerosol during the forest an d peat bog fires in the ETRin the summer of 2010. We assume that the ETR is theterritory bounded by coordinates 47°–65° N and 25°–55° E with an area of approximately 3.6 mln. km

Christian Theodor Vaupell, a Danish 19th century naturalist and a pioneering developer of the Quaternary geoscience

Abstract. Christian Theodor Vaupell (1821–1862) was a Danish scholar with pioneering investigations particularly on the late Quaternary development of bog forests, but also microscopy of plant anatomy and vegetative reproduction. His studies contributed to the early scientific thinking of the Quaternary environmental changes. Before his academic efforts, he had already survived the war between Prussia and Denmark albeit he became severely wounded and his left arm was amputated. The drama of his academic efforts, on the other hand, lies in the more or less suspicious dispute of his first doctoral thesis and his dismissal from the academic world during the following years. At the same time, he earned praise for his first thesis (never accepted as thesis but published as a regular book) from abroad; he was also able to attract private foundations for financial support of his scientific work. Following the enthusiasm of his time, Vaupell became attracted to the pine megafossils known to have been preserved in the bogs in north-west Europe. The megafossils led him to study not only the life systems of the ancient and modern bog forests but also their associations with Earth processes. As an interesting detail of his research, Vaupell made compound interpretations on the occurrence of megafossil stumps and their tree-ring growth patterns. In the course of the 20th century, Vaupell's studies have been cited as a general reference of post-glacial vegetation change and plant succession rather than clearly pioneering investigations of palaeoecology, an angle that we would like put into a contrasting perspective. To do so, we provide a brief portrait of Christian Vaupell and his research career. In conclusion, we wish to emphasize the comprehensiveness of Vaupell's views on the late Quaternary vegetation changes and the role of plant succession in that development.

Persistence of the Slow Growing Conifer Pilgerodendron uviferum in Old-Growth and Fire-Disturbed Southern Bog Forests

In spite of the extensive area of bogs in the southern cone of South America, there have been very few studies on structure and dynamics of conifer bog forests in this region. Previously, it has been assumed that in the absence of intensive disturbance, the dominant conifer Pilgerodendron uviferum (D. Don) Florin would be replaced through other angiosperm species. Here we hypothesized (a) that this conifer can persist without intensive disturbances and develop into old-growth forests with continuing regeneration and (b) that high-severity disturbances through fire threaten its local persistence. To test this hypotheses, we analyzed diameter and age structure, foliar and soil nutrient levels and the light environment of old-growth and fire-disturbed P. uviferum stands on Chiloe Island (43oS) in North Patagonia. Longevity (>880 years), extremely slow growth (<1 mm diameter per year) and tolerance to shade and stress are the main mechanisms of P. uviferum persistence in nutrient-poor and waterlogged conditions. Hence, old-growth P. uviferum forests are not a transitional phase in forest succession and may be maintained in the landscape for many centuries or millennia. However, in fire-disturbed stands, live trees of the species were rare and regeneration negligible, showing that high-severity fires can eliminate the species from parts of the landscape, where neither propagules nor seed trees survive. This underpins the importance of biological legacies such as seed trees for the recovery of disturbed sites, and points to the need for active restoration approaches to restore fire-degraded P. uviferum forests.

Late Quaternary vegetation, climate and fire dynamics, and evidence of early to mid-Holocene Polylepis forests in the Jimbura region of the southernmost Ecuadorian Andes

The vegetation, climate and fire history of high mountain ecosystems in the southern Ecuadorian Andes are documented in a continuous pollen and charcoal record, from Lagunas Natosas Forest bog, at 3495ma.s.l. spanning the late Pleistocene and Holocene periods since 15,930calyr BP. The chronology of this record is based on four radiocarbon dates. Páramo vegetation with abundant Poaceae and Plantago rigida characterized the Late Glacial (LG) period, implying cold and wet conditions. Slight expansions of mountain forests suggest warming during the LG. The upper forest line was lower than today and fire events were rare during the Pleistocene. During the early and mid-Holocene until 4300calyr BP, the area of páramo was markedly smaller and the subpáramo with woody vegetation (Melastomataceae) was larger. The upper mountain forest dominated and the upper forest line shifted to higher elevations. The pollen record provides the first evidence of the development of Polylepis forests in the southern part of the so-called Andean Depression reflecting warmer and drier climatic conditions during early and mid-Holocene. The late Holocene after about 4300calyr BP is characterized by larger areas of páramo and subpáramo promoted by moister conditions. These moister conditions and frequent fires may have been the cause of the very rare occurrence or even extinction of Polylepis populations in the Jimbura region. Since ca. 1000calyr BP human occupation has altered the landscape by frequent burning, wood cutting, grazing and cultivation.

Spatial distribution and mobility of butterflies in a population of the cranberry fritillary Boloria aquilonaris (Lepidoptera, Nymphalidae)

A population of the cranberry fritillary (Boloria aquilonaris) was studied in a forest bog in Southern Karelia. The butterflies in this habitat were distributed unevenly, forming large aggregations in the driest sites overgrown by Comarum palustre. All areas inhabited by the population were interconnected by fluxes of butterflies. The maximum recorded distance covered by a an individual was 1.5 km. The B. aquilonaris residence area was delimited on the basis of an exponential model. Specific features of the spatial organization of B. aquilonaris populations in spatially homogeneous and fragmented environments are discussed.

Long-term vegetation change in marshy pine forest Vaccinio uliginosi-Pinetum Kleist 1929

Długookresowe zmiany roślinności w zespole sosnowego boru bagiennegoVaccinio uliginosi-PinetumKleist 1929

Herbage production and live weight gain in dairy heifers grazing forest habitats in Norway

We examined the herbage production of different vegetation types and the live weight gain of dairy heifers grazing forest habitats over three consecutive years. Thirty-five heifers were grazing at high-grazing intensity (1 animal/ha) and 18 heifers at low-grazing intensity (0.5 animal/ha) in a ca. 15-year-old spruce forest with the vegetation types: bilberry spruce forest (57%); peat bogs (25%); and meadow spruce forest (18%). The herbage production was on average for all years highest in meadow spruce forest (2001 kg DM/ha), while it was similar in bilberry spruce forest and peat bogs (629 and 536 kg DM/ha, respectively). The average weight gain of the heifers was 509 g/d, with means ranging from 385 to 653 g/d for different years and grazing intensities. We conclude that estimates of herbage production were improved when the vegetation types of the grazing areas were taken into account.

Succession of a Southern Appalachian Mountain Wetland Six Years following Hydrologic and Microtopographic Restoration

Abstract Microtopography, which is known to play a key role in the structure and function of wetland communities, is receiving increasing attention in wetland restoration projects. One goal of the Tulula Wetlands Mitigation Bank, which was the first large‐scale wetland restoration project in the Blue Ridge Province, was to restore the microtopography in a degraded swamp forest–bog complex. This wetland type has become increasingly rare in the southern Appalachians and is characterized by a distinct microtopography of depressions and low ridges. We examined vegetation and soils in depression and ridge plots over a 6‐year period, during which the hydrology and microtopography of the floodplain were restored. Our results showed that the flora of the depression and ridge plots differed, with greater coverage by obligate wetland species in the depression plots but greater overall taxonomic richness in the ridge plots. The edaphic characteristics that we measured varied very little during the study period. Creating microtopographic relief during the restoration of this wetland seems to have provided a variety of niches and may have increased the likelihood that the site will succeed back to a swamp forest–bog complex, rather than as a forested terrace of Tulula Creek.

Disturbances on a Wooded Raised Bog—How Windthrow, Bark Beetle and Fire Affect Vegetation and Soil Water Quality?

Pinus rotundata dominated peatbog (Žofinka Nature Reserve) in the Třeboň Basin, Czech Republic, was affected by “natural” disturbances: wind damage (1984), followed by a bark beetle attack, and fire (1994, 2000). Phytosociological releves were used to document vegetation. Soil water chemistry was compared in three differently affected stands: (1) an undisturbed Pinus rotundata bog forest, (2) a windthrow – bark beetle affected stand and (3) a site burned by wildfire in 2000. The species composition of the windthrow – bark beetle affected sites and the undisturbed P. rotundata bog forest differed mainly in the shrub and tree layers. Burned sites were partly colonized by anemochorous species (e.g. Taraxacum sp. div.) that disappeared within two or three years after colonization. Bare peat was colonized by bryophytes (e.g. Marchantia polymorpha and Funaria hygrometrica) typical of the disturbed sites, and by Polytrichum sp. div. and Aulacomnium palustre. Most plant species characteristic of the P. rotundata bog forest occurred at the burned sites eight years after the fire, but in different abundances. The edificator of the former community—P. rotundata—was mostly absent. Compared with windthrow followed by the bark beetle attack, fire promoted rapid expansion of Molinia caerulea. Soil water in both the undisturbed P. rotundata bog forest and the windthrow – bark beetle affected sites had a similar composition: very low pH values, high P concentrations, low concentrations of cations (Ca2+, Mg2+and K+) and inorganic nitrogen. The concentrations of soluble reactive phosphorus (SRP) and \({\text{NH}}_4^ + - {\text{N}}\) were negatively correlated with the groundwater table. Total P, SRP and \({\text{NH}}_4^ + - {\text{N}}\) concentrations in the soil water at the burned site were by one order of magnitude higher than those in the P. rotundata bog forest, while concentrations of K+, Mg2+ and Ca2+ were only about two times higher. High concentrations of P and N in the soil water found three years after the fire indicated a long-term elevated nutrient content in the soil water.

Habitat and diet of young grouse broods: resource partitioning between Capercaillie (Tetrao urogallus) and Black Grouse (Tetrao tetrix) in boreal forests

We compared habitat use and diets of young Capercaillie and Black Grouse broods in a boreal forest in southeast Norway. We used pointing dogs to search for broods (N = 83) in mature “natural” forest types and examined the crop content of 66 chicks 1–9 weeks old. We also measured the abundance of insects in the habitats where broods were found. Although overlapping substantially in both habitat and diets, there were notable differences: Capercaillie broods were more frequently recorded in bilberry-dominated forest types, whereas Black Grouse preferentially used pine bog forest, a more open habitat with little bilberry. Capercaillie chicks ate proportionally more insects, particularly lepidopteran larvae, and insects dominated their diet for a longer period of time (until age 28–29 days) than in Black Grouse (14–15 days). After reaching their peaks, the quantity of insects in the crops declined rapidly especially in Capercaillie, and in one of 2 years this occurred at a time when insects, including larvae, were still abundant in the habitats. Among plant foods, both species ate large amounts of Bilberry (Vaccinium myrtillus) and Bog Whortleberry (V. uliginosum). The main difference between species was a large proportion of both over-wintered and new, not yet ripe, berries of Cranberry (Oxycoccus quadripetalus) in Black Grouse, and a higher proportion of the forb Melampyrum sylvaticum in Capercaillie. The difference in diets reflected their differential use of habitats; the Vaccinium-preferred habitats of Capercaillie were richer in insects, particularly larvae, than the pine bog habitat preferred by Black Grouse. Because insects, especially larvae, comprised a larger proportion of the diet of Capercaillie chicks and chicks of this species need more food to sustain their rapid growth, Capercaillie is likely to be more sensitive to variation in insect food than Black Grouse. Also, by reducing the abundance of bilberry, the main host plant of larvae chick food, clearcutting forestry has negative effects on the brood habitat quality of both species.

Wetland characterization using polarimetric RADARSAT-2 capability

The use of single-polarization (HH) RADARSAT-1 synthetic aperture radar (SAR) data has been shown to be important for wetland water extent characterization. However, the limited capability of the RADARSAT-1 single-polarization C-band SAR in vegetation type discrimination makes the use of clear-sky-dependent visible near-infrared (VNIR) satellite data necessary for wetland mapping. In this paper, the potential of polarimetric RADARSAT-2 data for wetland characterization is investigated. The Touzi incoherent decomposition is applied for the roll-invariant decomposition of wetland scattering. In contrast with the Cloude-Pottier decomposition that characterizes target scattering type with a real entity, α, the Touzi decomposition uses a complex entity, the symmetric scattering type, for unambiguous characterization of wetland target scattering. It is shown that, like the Cloude α scattering type, the magnitude αs of the symmetric scattering is not effective for vegetation type discrimination. The phase ϕαs of the symmetric scattering type has to be used for better characterization of wetland vegetation species. The unique information provided by ϕαs for an improved wetland class discrimination is demonstrated using Convair-580 polarimetric C-band SAR data collected over the Mer Bleue wetland in the east of Ottawa, Canada. The use of ϕαs makes possible the discrimination of shrub bog from sedge fen and even permits the discrimination between conifer-dominated treed bog and upland deciduous forest under leafy conditions.

Pyrogenic transformation of organic matter in soils of forest bogs

Natural fires on forest bogs significantly affect all the groups and fractions of peat organic matter. The type and intensity of the fires are responsible for the depth of the pyrogenic transformation of peat. In the course of thermal destruction of peat organic matter, humus substances (humic acids in particular) are accumulated, which leads to changes in the type of humus; the humus reserves may increase by 1.5–8 times. Several ways of the formation of humus components related to the intensity of a fire are suggested. The regressive evolution of bog ecosystems caused by fires is a reversible process. The humus status of pyrogenically transformed horizons and their morphology are preserved within the peat deposit as a relic characteristic of the discrete metamorphosis of the soils.

Multiparametric analysis of soil properties in the drained forest bogs of Western Siberia

The application of multiparametric statistical methods has confirmed that peat soils are different in the degree of their drainage and properties because of their modification during a 20–25 year period of artificial drainage operation. The following sequence represents the relative significance of the contribution to the soil changes of the parameters studied: groundwater table > air capacity > pH > 0T > Eh > water-soluble: C > Fe3+ > NH4+ and the activity of soil oxidoreductases in the following sequence: peroxidase > catalase > dehydrogenase. The necessity to supplement the substantive-genetic principle of the classification of drained peat soils with characterization of their water regime is substantiated.

&lt;em&gt;Cyclopyxis acmodonta&lt;/em&gt; n. sp. and &lt;em&gt;Arcella formosa&lt;/em&gt; n. sp.: Two New Species of Testate Rhizopods (Arcellinida, Protozoa) from Remnant Wetlands in Ontario, Canada

Species of the testate rhizopod genera Arcella and Cyclopyxis are found predominantly in the benthos of shallow ponds, forest pools, marshes and other freshwater habitats. Their taxonomy is based on the morphology of their tests — the shell-like structure that houses the living single-celled amoeboid protoplast. This paper describes a new species of Cyclopyxis discovered in two coniferous forest bogs, and a new species of Arcella from a Typha-dominated marsh on the north shore of Lake Ontario, Canada. Cyclopyxis acmodonta Nicholls n. sp. differs from its closest relative C. stellata (Wailes) Deflandre 1929 in its much smaller size and its irregularly shaped pseudostomal aperture, which is embellished with numerous, tiny, sharp-pointed toothlike quartz granules around the interior margin. Although the saucer-like indentations over the dorsal surface of the test of A. formosa Nicholls, Meisterfeld &amp; Török n. sp. resemble similar structures found in several other Arcella species, the large size of A. formosa (165-235 mm in diameter) and its low profile (low height-to-diameter ratio) are the main features distinguishing this new species from other Arcella species.

Petrography of the Neogene lignite from the Sofia basin, Bulgaria

The lignite seam from the Sofia Neogene basin has been sampled and the petrographical composition was determined. The coals contain high contents of macerals from the huminite group. The prevailing macerals from that group were textinite, ulminite and attrinite. Phlobaphinite, densinite and gelinite were observed rarely. Dominant macerals from the liptinite group were mainly suberinite, resinite, sporinite and cutinite. The amounts of the alginate, liptodetrinite and fluorinate were insignificant. The coal was very poor of macerals from the inertinite group. Fusinite, semifusinite, macrinite, sclerotinite and inertodetrinite were represented them. The main minerals were illite, kaolinite, halloyzite, pyrite, quartz, calcite and dolomite. Anorthite, amphibole, augite, chalcopyrite, marcasite, siderite, witherite, gypsum, melanterite and jarosite were also determined. The huminite maceral amount was highest in low part of the seam and lower in the middle part. The higher amount of the liptinite macerals was located in the middle and upper parts of the seam. Inertinite macerals were distributed uniformly on the seam profile and their amount was very low in the middle part of the seam. The middle part of the seam was contained highest amount of all minerals Illite was prevailing clay mineral in the middle part and kaolinite predominates in the low and upper parts of the seam. The type of the mire was determined as mesotrophic bog forest by Calder et al. [Bull. Soc. Geol. Fr. 162 (1991) 283], according to the Ground Water Index (GWI) and Vegetation Index (VI), calculated on the base of the maceral content. According to the petrography content, the Gelification Index (GI) and the Tissue Preservation Index (TPI), the peat bog probably originated as a fresh-water raised forest swamp.

Needle longevity of Scots pine in relation to foliar nitrogen content, specific leaf area, and shoot growth in different forest types

The aim of the study was to examine whether the variation in needle longevity of Scots pine (Pinus sylvestris L.) is of a community-specific nature. Altogether 300 trees were examined in Vaccinium, dry heath, and pine bog forests in Estonia. Mean number of needle age-classes was 4.1 for all forest types, while mean survivorship of needles averaged 70% in Vaccinium forests and 80% in the others (p &lt; 0.01). Mean mass-based nitrogen content (Nm) of the needles was the highest in Vaccinium forests (11.8 mg·g–1, p &lt; 0.05) and lower in dry heath (10.4 mg·g–1) and pine bog (9.8 mg·g–1) forests. Specific leaf area (SLA) did not differ between Vaccinium (6.3 mm2·mg–1) and dry heath (6.0 mm2·mg–1) forests but was lower in pine bog forests (5.5 mm2·mg–1, p &lt; 0.05). Shoot length increment was the smallest in pine bog forests (45.1 mm·year–1, p &lt; 0.05) and did not differ between Vaccinium (92.2 mm·year–1) and dry heath (95.2 mm·year–1) forests. Our findings confirm that the small-scale variation in needle longevity of Scots pine has a community-specific pattern and is in accordance with the trends in Nm and SLA.

Paleoseismology at high latitudes: Seismic disturbance of upper Quaternary deposits along the Castle Mountain fault near Houston, Alaska

Most paleoseismic studies are at low to moderate latitudes. Here we present results from a high-latitude (61°30′ N) trenching study of the Castle Mountain fault in south-central Alaska. This fault is the only one known in the greater Anchorage, Alaska, area with historical seismicity and a Holocene fault scarp. It strikes east-northeast and cuts glacial and postglacial sediments in an area of boreal spruce-birch forest, shrub tundra, and sphagnum bog. The fault has a prominent vegetation lineament on the upthrown, north side of the fault. Nine trenches were logged across the fault in glacial and postglacial deposits, seven along the main trace, and two along a splay. In addition to thrust and strike-slip faulting, important controls on observed relationships in the trenches are the season in which faulting occurred, the physical properties of the sediments, liquefaction, a shallow water table, soil-forming processes, the strength of the modern root mat, and freeze-thaw processes. Some of these processes and physical properties are unique to northern-latitude areas and result in seismic disturbance effects not observed at lower latitudes. The two trenches across the Castle Mountain fault splay exposed a thrust fault and few liquefaction features. Radiocarbon ages of soil organic matter and charcoal within and overlying the fault indicate movement on the fault at ca. 2735 cal. (calendar) yr B.P. and no subsequent movement. In the remaining seven trenches, surface faulting was accompanied by extensive liquefaction and a zone of disruption 3 m or more wide. The presence of numerous liquefaction features at depths of <0.5–1.0 m indicates faulting when the ground was not frozen—i.e., from about April to October. Sandy-matrix till, sand, silt, gravel, and pebbly peat were injected up to the base of the modern soil, but did not penetrate the interlocking spruce-birch root mat. The strength of the root mat prohibited development of a nonvegetated scarp face and colluvial wedge. In only one trench did we observe a discrete fault plane with measurable offset. It lay beneath a 2-m-thick carapace of liquefied sand and silt and displayed a total of 0.9–1.85 m of thrust motion since deposition of the oldest deposits in the trenches at ca. 13,500 yr B.P. We found liquefaction ejecta on paleosols at only one other trench, where there were bluejoint ( Calamagrostis canadensis ) tussocks that lacked an extensive root mat. From crosscutting relationships, we interpret three paleoliquefaction events on the main trace of the Castle Mountain fault: 2145–1870, 1375–1070, and 730–610 cal. yr B.P. These four earthquakes on the Castle Mountain fault in the past ∼2700 yr indicate an average recurrence interval of ∼700 yr. As it has been 600–700 yr since the last significant earthquake, a significant (magnitude 6–7) earthquake in the near future may be likely. Paleoseismic data indicate that the timing and recurrence interval of megathrust earthquakes is similar to the timing and recurrence interval of Castle Mountain fault earthquakes, suggesting a possible link between faulting on the megathrust and on “crustal” structures.

Clostridium uliginosum sp. nov., a novel acid-tolerant, anaerobic bacterium with connecting filaments.

An anaerobic, acid-tolerant bacterium, CK55T, was isolated from an acidic forest bog. Cells of CK55T stained Gram-negative but did not have an outer membrane. Cells were spore-forming, motile rods with peritrichous flagella, formed chains or aggregates and were linked by connecting filaments that were composed of a core and outer sheath. Cellobiose, glucose, xylose, mannose, mannitol, sucrose and peptone supported growth. Arabinose, lactose, raffinose, H2/CO2, CO/CO2, vanillate, Casamino acids and various purines and pyrimidines did not support growth. Growth on carbohydrates yielded acetate, butyrate, lactate, formate and H2 as end-products. Growth was observed at pH 4.0-9.0, with an optimum at pH 6.5, and at 10-30 degrees C, with an optimum at 20-25 degrees C. At 20 degrees C, doubling times were 4 and 6 h at pH 6.5 and 4.0, respectively. Hydrogenase activity in cell-free extracts was 12 U (mg protein)-1. CK55T did not: (i) contain detectable levels of CO, formate, lactate dehydrogenases or cytochromes; (ii) carry out dissimilatory reduction of nitrate or sulfate; or (iii) produce methane. Thus, CK55T was characterized as a non-acetogenic, fermentative chemo-organotroph. The G+C content of CK55T was 28.0 mol%. CK55T was phylogenetically most closely related to Clostridium botulinum (types B, E and F), Clostridium acetobutylicum and other saccharolytic clostridia; the 16S rRNA gene sequence similarity values to the nearest relatives of CK55T were approximately 97%. Based on morphological, physiological and phylogenetic properties of CK55T, it is proposed that CK55T be termed Clostridium uliginosum sp. nov. (= DSM 12992T = ATCC BAA-53T).

Dendroecology and climatic impacts for a relict, old-growth, bog forest in the Ridge and Valley Province of central Pennsylvania, U.S.A.

We report on the 440-year dendrochronological history of a relict, bog forest in the Ridge and Valley Province of central Pennsylvania that contains extreme southern, disjunct populations of Picea mariana (Mill.) BSP and Abies balsamea (L.) Mill. The forest is dominated by Tsuga canadensis (L.) Carr. (49% relative importance value), Picea mariana (16%), and Acer rubrum L. (15%). The few remaining Abies balsamea trees are in a advanced state of decline. Many Nyssa sylvatica Marsh. and T. canadensis trees recruited from 1560 and 1700, respectively, until 1890. However, the majority of the other tree species recruited during a 40-year period following selective logging of the forest in the 1890s and fires in about 1900 and 1914. We found a scarcity of tree saplings and no evidence of recruitment into the tree-size class for any species after 1950. The master tree-ring chronology for both N. sylvatica and T. canadensis exhibits a marked increase after the 1890s logging and a decrease after a 1900 fire. In addition, a large number of releases in individual tree chronologies occurred over the last 400 years, indicating the frequent occurrence of small-scale disturbances. Tree-ring growth during the 20th century was reduced by droughts and cool temperatures in the 1920s and in the early to middle 1960s. Abies balsamea cores exhibit a marked growth decline in 1986. Tsuga canadensis growth was very low between 1970 and 1998, despite a generally warm and wet climate during that time. Picea mariana had a dramatic increase in growth during very warm and wet climate between 1995 and 1998. Most Abies balsamea trees have reached their pathological age of 50-85 years and have active Armillaria root rot, insect infestations, and very poorly developed crowns. These symptoms or severe growth declines are not present in Picea mariana. It appears that the 10 000 year history of Abies balsamea presence at Bear Meadows will end soon, with no opportunity to reestablish itself because of the lack of a local seed source. The results of this study suggest that relict tree populations in the eastern United States may be particularly sensitive to direct and indirect anthropogenic impacts and climatic variations, and represent important benchmarks for comparisons with future studies.Key words: tree rings, disturbance, climate, global change, central Pennsylvania.

Dendroecology and climatic impacts for a relict, old-growth, bog forest in the Ridge and Valley Province of central Pennsylvania, U.S.A.

Dendroecology and climatic impacts for a relict, old-growth, bog forest in the Ridge and Valley Province of central Pennsylvania, U.S.A.