Magellanic Moorland Research Articles

Kawesar artigasi, new genus and species of Chrysomelidae (Coleoptera) associated to peatlands in the Magellanic Moorland biogeographic province, Chile

Se describe Kawesqar gen. nov. y Kawesqar artigasi sp. nov. para la fauna de crisomélidos del extremo austral de Sudamérica. Se entregan imágenes y caracteres diagnóstico para los taxa.

Tabula rasa in the Patagonian Channels II: The cushion peat bog species Astelia pumila (Asteliaceae) and Donatia fascicularis (Stylidiaceae) survived the last glacial in south‐central Chile

AbstractAimPlant phylogeographic data from the Patagonian Channels are scant and it is largely unknown how the extensive Quaternary glaciations affected the population dynamics of the region's major vegetation component, that is cushion peat bogs (Magellanic moorland). Whether ice‐age glaciers wiped out all terrestrial plant life or whether some populations persisted in situ remains unclear. We reconstructed the phylogeography of two dominant Patagonian cushion peat bog species, Astelia pumila (G.Forst.) Gaudich. (Asteliaceae) and Donatia fascicularis J.R.Forst. & G.Forst. (Stylidiaceae), to test (a) the hypothesis of a glacial refugium for moorland plants in south‐central Chile and (b) the tabula rasa scenario for the Patagonian Channels. The retrieved phylogeographic patterns were compared with those reported previously for a further cushion peat bog species (Pfanzelt et al., Molecular Ecology 26, 4027–4044), with the objective to provide a broader picture of how West Patagonian moorland plants responded to the Quaternary ice‐ages.LocationWest and Fuegian Patagonia, and the Falkland Islands (Islas Malvinas), southern South America.MethodsDNA sequence data from seven and fourteen, respectively, nuclear loci containing Simple Sequence Repeats of 371 and 328 individuals of the two study species were analysed using population genetic summary statistics, phylogenetic networks and Bayesian and multivariate methods to determine genetic structure. Ecological niche modelling was used to reconstruct the spatial distribution of suitable habitat at the Last Glacial Maximum.ResultsAll A. pumila populations belong to a single population genetic cluster. In the case of D. fascicularis, only the northernmost sampled population from Nahuelbuta (Chile) is genetically distinct, whereas the remainder forms a cluster without much further substructure. According to palaeodistribution models, south‐central Chile offered suitable habitat during the last glacial.Main conclusionBoth ecological niche modelling and the very low genetic subdifferentiation are congruent with a tabula rasa scenario for the Patagonian Channels. Populations survived the last glacial in south‐central Chile, in an area to the northwest of the ice sheet. From there, southern regions were recolonized through highly bottlenecked source populations. Other, non‐mutually exclusive factors may have further shaped the population genetic patterns, among them high gene flow mediated by the strong westerly winds.

Middle to Late Holocene mobilization of DOC-bound Pb and Y in the Magellanic moorlands (53° S) as a function of sea spray fertilization, climate variations and volcanic fallout? A preliminary report

Middle to Late Holocene mobilization of DOC-bound Pb and Y in the Magellanic moorlands (53° S) as a function of sea spray fertilization, climate variations and volcanic fallout? A preliminary report

Map and shapefile of the biogeographic provinces of Argentina.

We provide a map of the 15 biogeographic provinces of Argentina based on the ecoregions recognized for the country, combining climatic, geological and biotic criteria. Argentinean provinces belong to the Neotropical region (Yungas, Paraná Forest, Araucaria Forest, Chaco and Pampean provinces), the South American transition zone (Puna, Monte, Comechingones and Cuyan High Andean provinces) and the Andean region (Patagonian, Maule, Valdivian Forest, Magellanic Forest, Falkland Islands and Magellanic Moorland provinces). In order to facilitate future biogeographic analyses, we provide a file of this biogeographical regionalisation in vector format using the World Geodetic Survey 1984.

Track analysis of agaricoid fungi of the Patagonian forests

Agaricoid fungi from Patagonia have been vastly studied taxonomically since 1887, and more recently ecologically. We found five generalised tracks and three nodes for a selection of nine ectomycorrhizal and nine saprophytic species. Two areas are supernodes, complex areas supported by many nodes. One of these supernodes could be a result of a lack of sampling in the Strait of Magellan area. The other could imply a biotic radiation and a differential tolerance to more arid climate conditions in the Andes mountain chain around 44.3°S, 71.5°W. Two important areas to focus future sampling of agaricoid fungi are suggested. Generalised tracks obtained match those found for weevils (Coleoptera: Curculionidae) and oribatid mites (Acari: Oribatida) distributed along the Magellanic Forest and Magellanic Moorland provinces of the Andean region. Overlap of generalised tracks among unrelated taxa supports the idea that common processes might have caused the observed patterns. The most significant and undeniable fact is that fungal species present ecological traits that can be vital for studying geological events that have marked the biotic development.

Reconstrucción de la vegetación posglacial y su relación con el ascenso relativo del nivel del mar en el extremo este del canal Beagle, Tierra del Fuego, Argentina

The coast-line evolution and vegetation from the Last Glacial Maximum (LGM, ca. 25 ka cal AP) until the middle Holocene are reconstructed from a digital terrain model and a postglacial sea level curve and pollen analysis of a Donatia-Astelia cushion bog located in Punta Moat (Moat-2; 54°58’50’’S, 66°44’10’’W; 40 m s.n.m.), east Beagle Channel. The evolution of plant communities at eastern mouth of the Beagle Channel is broadly in line with the regional postglacial vegetation pattern in areas devoid of ice south of Tierra del Fuego. The regional pattern of postglacial vegetation shows steppe followed by forest-steppe and closed Nothofagus forest. Prior 17,700 cal yr BP, the onset of deglaciation in the Beagle Channel in the current study area of Punta Moat and, the removal of alpine paleoglaciers to the headwaters of the valleys and cirques of Sierra Lucio Lopez, led the formation of an alluvial plain with streams flowing in a perpendicular direction to the current channel. During the early Holocene (11,500-8,000 cal yr BP), the vegetation was similar to that developed in the western and central sectors of the Beagle Channel. However, the influence of the relative rise of the sea-level and the marine spray-humidity favored the early development of Nothofagus forest in Punta Moat. By 9,500 cal yr BP the landscape showed the physiognomy of a closed forest. Meanwhile on the peat bog, the Sphagnum-cushion plant mixed type prevailed, including floristic elements characteristics of the Magellanic Moorland, due to mineral input from sea spray in coincidence with the opening of channels and the Picton and Nueva islands formation. Towards the ca. 7,000 cal yr BP, the Magellanic Moorland and the Subantarctic Evergreen Forest developed when the coast-line configuration was similar than today.

Vegetation and climate changes during the last 22,000 yr from a marine core near Taitao Peninsula, southern Chile

High-temporal resolution of pollen analyses from marine core MD07-3088 (46°S) documents regional and coastal vegetation changes in the mid-latitude of southern Chile during the last 22kyr BP. The coastal margin was partly ice-free during the last glacial period with the presence of scattered vegetation. After~17.6kyr BP, the expansion of Nothofagus woodland highlights a warming trend and marks the beginning of the last deglaciation. The deglacial forest expansion is interrupted by the development of Magellanic moorland simultaneously with the Antarctic Cold Reversal. This vegetation change illustrates a pause in the warming trend with an abrupt increase in precipitation which is related to strong intensity of Southern Westerly Winds. After 12.8kyr BP, the retreat of Magellanic moorland illustrates a second-step warming that is strengthened after 11.5kyr at the onset of the Holocene. Expansion of heliophytic taxa illustrates warmest and driest conditions of the Holocene from 11 to 7.4kyr BP. Later, the decrease of heliophytic taxa shows a return to cooler and wetter conditions, illustrated by the presence of the North Patagonian rainforest that reaches modern condition after 5kyr. Climate changes inferred from the marine pollen record are consistent with geochemical data changes from the same samples and illustrate a clear synchronicity with δD variations of EPICA Dome C ice core during the last deglaciation and Holocene. Comparison between vegetation changes from the marine core and regional palaeoclimatic records highlights southward-northward shifts of the Southern Westerly Wind belt and supports a close link between Southern Westerly Wind belt and atmospheric CO2 variability during the last deglaciation.

Magellanic Moorland Expansion during the Antarctic Cold Reversal from Coastal Vegetation Changes in the Taitao Peninsula, Chile

Magellanic Moorland Expansion during the Antarctic Cold Reversal from Coastal Vegetation Changes in the Taitao Peninsula, Chile

Island evolutionary biogeography: analysis of the weevils (Coleoptera: Curculionidae) of the Falkland Islands (Islas Malvinas)

Aim I analysed distributional and phylogenetic information on weevils (Coleoptera: Curculionidae) from the Falklands, and integrated it with molecular, palaeontological and geological information to infer a geobiotic scenario. Location Falkland Islands (Islas Malvinas). Methods The panbiogeographical analysis was based on data on 23 Falkland species and their related taxa from southern South America. For the cladistic biogeographical analysis I analysed six weevil taxa for which phylogenetic hypotheses are available (the generic groups Cylydrorhinus, Strangaliodes and Falklandius, and the genera Antarctobius, Germainiellus and Puranius). Results from this analysis were compared with previous regionalizations. Cenocrons (sets of taxa that share the same biogeographical history) were identified by considering temporal information provided by fossils and molecular clocks. Finally, a geobiotic scenario was proposed by integrating the available information. Results Six generalized tracks were detected: Maule–Valdivian forests, Magellanic forest, Magellanic moorland, Falkland Islands, Magellanic forest–Magellanic moorland, and Magellanic forest–Falkland Islands. A node was identified in the Magellanic forest, based on the overlap of two generalized tracks. A single general area cladogram was obtained, implying the following sequence: (Magellanic moorland (Maule–Valdivian forests (Magellanic forest, Falkland Islands))). The Falklands are classified here as a biogeographical province in the Austral realm, Andean region and Subantarctic subregion. Falkland weevils seem to belong to a single Subantarctic cenocron. The sequence of events deduced implies the following steps: development of the Subantarctic biota in southern South America, arrival of the Falkland crustal block from South Africa in the Early Cretaceous, geodispersal of the Subantarctic cenocron from southern South America to the Falklands during the Early Oligocene, vicariance of the Magellanic moorland, vicariance of the Maule–Valdivian forests, and final vicariance between the Magellanic forest and the Falkland Islands. Main conclusions The biotic components identified support the connection of the Falkland weevils with the Magellanic forest. Falkland weevils belong to a single cenocron, dated to at least the Early Oligocene, when geodispersal from southern South America may have occurred. An older African cenocron may have been replaced completely by the Subantarctic one when the proto-Falklands made contact with the Patagonian continental shelf. A geobiotic scenario implying vicariance events related to sea-level variations could explain the distributional patterns analysed herein.

Halogens in pore water of peat bogs – the role of peat decomposition and dissolved organic matter

Abstract. Halogens are strongly enriched in peat and peatlands and such they are one of their largest active terrestrial reservoir. The enrichment of halogens in peat is mainly attributed to the formation of organohalogens and climatically controlled humification processes. However, little is known about release of halogens from the peat substrate and the distribution of halogens in the peat pore water. In this study we have investigated the distribution of chlorine, bromine and iodine in pore water of three pristine peat bogs located in the Magellanic Moorlands, southern Chile. Peat pore waters were collected using a sipping technique, which allows in situ sampling down to a depth greater than 6m. Halogens and halogen species in pore water were determined by ion-chromatography (IC) (chlorine) and IC-ICP-MS (bromine and iodine). Results show that halogen concentrations in pore water are 15–30 times higher than in rainwater. Mean concentrations of chlorine, bromine and iodine in pore water were 7–15 mg l−1, 56–123 μg l−1, and 10–20 μg l−1, which correspond to mean proportions of 10–15%, 1–2.3% and 0.5–2.2% of total concentrations in peat, respectively. Organobromine and organoiodine were the predominant species in pore waters, whereas chlorine in pore water was mostly chloride. Advection and diffusion of halogens were found to be generally low and halogen concentrations appear to reflect release from the peat substrate. Release of bromine and iodine from peat depend on the degree of peat degradation, whereas this relationship is weak for chlorine. Relatively higher release of bromine and iodine was observed in less degraded peat sections, where the release of dissolved organic carbon (DOC) was also the most intensive. It has been concluded that the release of halogenated dissolved organic matter (DOM) is the predominant mechanism of iodine and bromine release from peat.

The Patagonian species of the genus Atrichopogon Kieffer, with a biogeographic analysis based on Forcipomyiinae (Diptera: Ceratopogonidae)

AbstractThe following five new species of Atrichopogon Kieffer from southern Argentina and Chile are described and illustrated: A. aridus Spinelli & Marino, A. comechingon S. & M., A. endemicus S. & M., A. inacayali S. & M. and A. similis S. & M. A. aridus and A. comechingon also occur north of Patagonia. The previously known species A. obfuscatus Ingram & Macfie is redescribed, and notes on its type are provided. A key to recognition of males and females of the seven species inhabiting Patagonia is included. A biogeographic parsimony analysis of endemicity (PAE) interprets the relationships among the provinces of the southern South America. It is based on seven areas of endemism and distributional data of 30 species of the subfamily Forcipomyiinae. The analysis results in two most parsimonious cladograms and their strict consensus depicts the following relationships: ((Monte, Patagonian steppe) (Central Chile, Magellanic Moorland (Magellanic Forest, Maule, Valdivian Forest))).

Abrupt vegetation changes during the last glacial to Holocene transition in mid‐latitude South America

AbstractA pollen record from the Huelmo site (ca. 41°30′S) shows that vegetation and climate changed at millennial time‐scales during the last glacial to Holocene transition in the mid‐latitude region of western South America. The record shows that a Nothofagus parkland dominated the landscape between 16 400 and 14 600 14C yr BP, along with Magellanic Moorland and cupressaceous conifers. Evergreen North Patagonian rainforest taxa expanded in pulses at 14 200 and 13 000 14C yr BP, following a prominent rise in Nothofagus at 14 600 14C yr BP. Highly diverse, closed canopy rainforests dominated the lowlands between 13 000 and 12 500 14C yr BP, followed by the expansion of cold‐resistant podocarps and Nothofagus at ca. 12 500 and 11 500 14C yr BP. Local disturbance by fire favoured the expansion of shade‐intolerant opportunistic taxa between 10 900 and 10 200 14C yr BP. Subsequent warming pulses at 10 200 and 9100 14C yr BP led to the expansion of thermophilous, summer‐drought resistant Valdivian rainforest trees until 6900 14C yr BP.Our results suggest that cold and hyperhumid conditions characterised the final phase of the Last Glacial Maximum (LGM), between 16 400 and 14 600 14C yr BP. The last ice age Termination commenced with a prominent warming event that led to a rapid expansion of North Patagonian trees and the abrupt withdrawal of Andean ice lobes from their LGM positon at ca. 147 000 14C yr BP. Hyperhumid conditions prevailed between 16 400 and 13 000 14C yr BP, what we term the ‘extreme glacial mode’ of westerly activity. This condition was brought about by a northward shift and/or intensification of the southern westerlies. The warmest/driest conditions of the last glacial–interglacial transition occurred between 9100 and 6900 14C yr BP. During this period, the westerlies shifted to an ‘extreme interglacial mode’ of activity, via a poleward migration of stormtracks. Our results indicate that a highly variable climatic interval lasting 5500 14C years separate the opposite extremes of vegetation and climate during the last glacial‐interglacial cycle, i.e. the end of the LGM and the onset of the early Holocene warm and dry period. Copyright © 2003 John Wiley & Sons, Ltd.

Effect of peat decomposition and mass loss on historic mercury records in peat bogs from patagonia.

Ombrotrophic peat bogs have been widely used to evaluate long-term records of atmospheric mercury (Hg) deposition. One of the major aims of these investigations is the estimation of the increase in atmospheric Hg fluxes during the industrial age compared to preindustrial fluxes. Comparability of Hg accumulation rates calculated from density, peat accumulation rates, and Hg concentrations requires linearity between these parameters. Peat formation is a dynamic process accompanied by intense mass loss and alteration of the organic material. Our investigations on three peat cores from the Magellanic Moorlands, Chile, indicate that Hg concentrations in peat strongly depend on peat humification. Moreover, differences in mass accumulation rates during peat evolution are not compensated by linear changes in density, peat accumulation, or Hg concentrations. We suggest that Hg accumulation rates be normalized to carbon accumulation rates to achieve comparability of Hg accumulation rates derived from differently altered peat sections. Normalization to the carbon accumulation rates reduces Hg accumulation rates in less degraded peat sections in the upper peat layers by factors of more than 2. Our results suggest that the increase in Hg deposition rates during modern times derived from ombrotrophic peat bogs are potentially overestimated if Hg accumulation rates are not corrected for mass accumulation rates.

Elevated mercury accumulation in a peat bog of the Magellanic Moorlands, Chile (53°S) – an anthropogenic signal from the Southern Hemisphere

Increasing mercury deposition rates in the Northern Hemisphere recorded in natural archives such as peat bogs or lake sediments have been documented in numerous studies. However, data on atmospheric Hg deposition in the Southern Hemisphere dating back to pre-industrial times are rare. Here, we provide a continuous record of atmospheric Hg deposition in the Southern Hemisphere recorded by an ombrotrophic peat bog of the Magellanic Moorlands, Chile (53°S), extending back 3000 yr. Pre-industrial mercury accumulation rates range between 2.5 and 3.9 μg/m 2/yr. In the past 100 yr, Hg accumulation rates increased 18-fold from about 3 μg/m 2/yr to a maximum of 62.5 μg/m 2/yr. If Hg accumulation rates were normalized to peat accumulation rates, maximum rates were 7.9 μg/m 2/yr, which is only 2.5 times the pre-industrial rates. Thus, Hg accumulation rates normalized to peat accumulation rates are more comparable to the three-fold net increase in atmospheric Hg concentrations estimated for the same period. We suggest that the increase in Hg accumulation rates in the Magellanic Moorlands within the past 100 yr is at least partly attributed to global dispersion of Hg derived from anthropogenic sources in the Northern Hemisphere. The finding that no increase of atmospheric deposition of Pb could be observed in the bog indicates the extraordinary long-range transport and ubiquitous dispersion of anthropogenic derived gaseous Hg compared to other metals.

Abrupt vegetation and climate changes during the last glacial maximumand last termination in the chilean lake district: a case study from canal de la puntilla (41°s)

ABSTRACT. Multiple overlapping and replicate pollen stratigraphies from Canal de la Puntilla (40°57’09”S, 72°54’18”W, 120 m elevation) reveal that a Nothofagus dombeyi‐type parkland occupied the Valle Central of the Chilean Lake District during the portion of the Last Glacial Maximum between 20,200 and about 14,600 14C yr BP. Dominating this landscape was Nothofagus dombeyi‐type and Gramineae, accompanied by taxa commonly found today in Subantarctic environments and above the Andean tree‐line in the Lake District (Perezia‐type, Valeriana, and Huperzia selago), along with cushion bog taxa characteristic of Magellanic Moorlands (Donatia fascicularis and Astelia pumila). Within this open landscape Nothofagus dombeyi‐type expanded between 20,200 and 15,800 14C yr BP, interrupted by a brief reversal between 19,200 and 18,800 14 C yr BP and followed by a prominent increase in Gramineae pollen between 15,800 and about 14,600 14C yr BP. A major rise of Nothofagus dombeyi‐type began at about 14,600 14C yr BP, followed by decline in non‐arboreal taxa and a remarkable expansion of North Patagonian Rain Forest taxa in pulses centered at 14,200 and 13,000 14C yr BP. Podocarpus nubigena expanded between 12,200 and 9800 14C yr BP, along with increases in Misodendrum and Maytenus disticha‐type between 11,000 and 9800 14C yr BP.Paleovegetation records suggest that mean annual temperature was 6–7°C colder than at present during the coldest episodes between 20,200 and about 14,600 14C yr BP, with twice the modern annual precipitation between 20,200 and 13,000 14C yr BP, suggesting a northward shift and intensification of westerly stormtracks. Slight climate warming occurred between 20,200 and 15,800 14C yr BP, interrupted by cooling events at 19,200 and 15,800 14C yr BP. The initial warming of the last termination started at 14,600 14C yr BP, followed by warming pulses at 14,200 and 13,000 14C yr BP. These events brought glacial conditions to a cool‐temperate climate, slightly cooler and wetter than modern climate, accounting for a total temperature recovery of ≥5°C by about 13,000 14C yr BP. A general reversal in trend is inferred with cooling events at 12,200 and 11,000 14C yr BP.

Soil organic carbon and nutrient status in old-growth montane coniferous forest watersheds, Isla Chiloé, Chile

Montane temperate forests of the Cordillera de Piuchue Ecosystem Study, Isla Chiloe, Chile, are unaffected by air pollution, timber exploitation and agricultural clearing, and the current floristic assemblage has been relatively stable for the past 7500 years. The apparent absence of major perturbation at this location makes it an appropriate baseline site for ecosystem analysis. We measured soil bulk density, pH, soil organic C (SOC), total N, and NH4Cl–exchangeable cations (Ca+2, Mg+2, K+, Na+, Al+3) in 0–10 and 10–40 cm depth samples from 72 soil profiles representing three vegetation zones: Fitzroya cupressoides Forest, Pilgerodendron uvifera–Tepualia stipularis Forest, and Magellanic Moorland. Fitzroya and Pilgerodendron–Tepualia Forests were indistinguishable for all measured soil characteristics (P > 0.05, Dunn's multiple comparison test on ranked data); these included very high median SOC concentrations (0–10 cm = 49.6%) and correspondingly low bulk density values (0–10 cm = 0.07). Moorland soil median values (0-10 cm) were significantly higher for bulk density (0.12) and lower for SOC (28.5%), but not for total N (Forests = 0.99%, Moorland = 0.95%), resulting in lower median C:N ratios for the moorland (Forests = 44.7; Moorland = 30.3). Across both depths and all three vegetation zones regression analysis indicated that SOC was an excellent predictor (R2; = 0.93, P < 0.001) of Σ (exchangeable Ca+2 + Mg+2 + K+ + Na+). Comparison with other old growth montane environments indicates that the Fitzroya and Pilgerodendron–Tepualia soil profiles are characterized by C:N ratios typical of other relatively unpolluted conifer forest soils (33.0–49.3). Soil profiles of representative polluted montane conifer forests have lower C:N ratios (16.2–23.5). Organic horizons from representative polluted montane conifer forests also retain fewer exchangeable base cations per unit SOC than are retained by organic horizons from the Cordillera de Piuchue forests.

Vegetation and climate near Lago Llanquihue in the Chilean Lake District between 20200 and 950014C yr BP

Radiocarbon-dated pollen records of two adjacent sediment cores from Canal de la Puntilla (40°57′09″S, 72°54′18″W) in the Chilean Lake District reveal that a sparsely vegetated landscape prevailed during the portion of the Last Glacial Maximum between 20200 and about 14800 14C yr BP. Dominating the vegetation was Nothofagus, Gramineae and Compositae, along with taxa commonly found today above the Andean treeline (Perezia-type, Valeriana) and in Magellanic Moorlands (Donatia, Astelia). Nothofagus expanded between 20200 and 15800 14C yr BP, interrupted by a reversal at 19200 14C yr BP and followed by a prominent increase in Gramineae pollen between 15800 and about 14800 14C yr BP. A major increase in Nothofagus started at about 14800 14C yr BP, followed by an abrupt expansion of thermophilous Valdivian/North Patagonian Rain Forest taxa (Myrtaceae, Lomatia/Gevuina, Hydrangea, etc.) at about 14000 14C yr BP. An opening of the rain forest and an expansion of Podocarpus nubigena, Misodendrum, and Maytenus disticha-type subsequently occurred between 11000 and 10000 14C yr BP. These results suggest that mean annual temperature was 6–7°C colder than at present, with twice the modern annual precipitation between 20200 and 14000 14C yr BP, implying a northward shift and intensification of the westerlies storm-tracks. Slight climate warming occurred between 20200 and 15800 14C yr BP, featuring cooling reversals at 19200 14C yr BP, and later at 15800 14C yr BP. The warming of the last termination started at about 14800 14C yr BP, and reached a total temperature rise of ≥5°C by 12400 14C yr BP, followed by cooling between 11000 and 10000 14C yr BP. © 1997 John Wiley & Sons, Ltd.

Vegetation and climate near Lago Llanquihue in the Chilean Lake District between 20200 and 9500 14C yr BP

Radiocarbon-dated pollen records of two adjacent sediment cores from Canal de la Puntilla (40°57′09″S, 72°54′18″W) in the Chilean Lake District reveal that a sparsely vegetated landscape prevailed during the portion of the Last Glacial Maximum between 20200 and about 14800 14C yr BP. Dominating the vegetation was Nothofagus, Gramineae and Compositae, along with taxa commonly found today above the Andean treeline (Perezia-type, Valeriana) and in Magellanic Moorlands (Donatia, Astelia). Nothofagus expanded between 20200 and 15800 14C yr BP, interrupted by a reversal at 19200 14C yr BP and followed by a prominent increase in Gramineae pollen between 15800 and about 14800 14C yr BP. A major increase in Nothofagus started at about 14800 14C yr BP, followed by an abrupt expansion of thermophilous Valdivian/North Patagonian Rain Forest taxa (Myrtaceae, Lomatia/Gevuina, Hydrangea, etc.) at about 14000 14C yr BP. An opening of the rain forest and an expansion of Podocarpus nubigena, Misodendrum, and Maytenus disticha-type subsequently occurred between 11000 and 10000 14C yr BP. These results suggest that mean annual temperature was 6–7°C colder than at present, with twice the modern annual precipitation between 20200 and 14000 14C yr BP, implying a northward shift and intensification of the westerlies storm-tracks. Slight climate warming occurred between 20200 and 15800 14C yr BP, featuring cooling reversals at 19200 14C yr BP, and later at 15800 14C yr BP. The warming of the last termination started at about 14800 14C yr BP, and reached a total temperature rise of ≥5°C by 12400 14C yr BP, followed by cooling between 11000 and 10000 14C yr BP. © 1997 John Wiley & Sons, Ltd.

Palaeoecology of a Donatia-Astelia cushion bog, Magellanic Moorland-Subantarctic evergreen forest transition, southern Tierra del Fuego, Argentina

Cushion bogs are an integral feature of Magellanic Moorland of subantarctic, southernmost Chile (48–56°S). The palaeoecology of an outlying cushion-type bog at Bahia Moat, located in moorland-forest vegetation on the southeastern coast of Argentine Tierra del Fuego, traces the 7000 yr development of the site, local and surrounding vegetational history, and palaeoclimate. Pollen and spore stratigraphy indicates that cushion plants, Donatia and Astelia, characterized the bog over the past 2600 yr. Regional vegetation became forest-dominated after 4750 yr BP, following displacement of open communities of Gramineae and Compositae by the evergreens Nothofagus betuloides and Drimys winteri. Increased precipitation/evaporation ratios in effect during the late Holocene were coupled with lower temperatures, contrasting less humid, moderated conditions with high fire incidence prevailing early in the bog record.

Glacial climates and their effects on the history of the vegetation of Chile: A synthesis based on palynological evidence from Isla de Chiloé

Palynological evidence from Isla de Chiloé (42–43°S) suggests that hygrophyllous plant formations expanded northwards during the Late Pleistocene in Southern Chile. North Patagonian-Subantartic forest developed between 40,000 and 33,000 yr B.P.; followed between c. 27,000 and c. 13,500 and 12,500 yr B.P. by a Magellanic moorland mosaic. From this date onwards, forest taxa predominate in all the pollen records. Comparing these results with the present distribution of relict vegetation on the Coastal Range of Chile, and also with paleoenvironmental data for Central Chile, I suggest that, during the Pleistocene, rainfall increased along the west coast of southern America, between 30° and 43°S, probably due to the increased influence of the westerlies.