Changes in climate and fire regime have long been recognized as drivers of the postglacial vegetation history of Yellowstone National Park, but the effects of locally dramatic hydrothermal activity are poorly known. Multi-proxy records from Goose Lake have been used to describe the history of Lower Geyser Basin where modern hydrothermal activity is widespread. From 10,300 cal yr BP to 3800 cal yr BP, thermal waters discharged into the lake, as evidenced by the deposition of arsenic-rich sediment, fluorite mud, and relatively high δ13Csediment values. Partially thermal conditions affected the limnobiotic composition, but prevailing climate, fire regime, and rhyolitic substrate maintained Pinus contorta forest in the basin, as found throughout the region. At 3800 cal yr BP, thermal water discharge into Goose Lake ceased, as evidenced by a shift in sediment geochemistry and limnobiota. Pollen and charcoal data indicate concurrent grassland development with limited fuel biomass and less fire activity, despite late Holocene climate conditions that were conducive to expanded forest cover. The shift in hydrothermal activity at Goose Lake and establishment of the treeless geyser basin may have been the result of a tectonic event or change in hydroclimate. This record illustrates the complex interactions of geology and climate that govern the development of an active hydrothermal geo-ecosystem.

The postglacial vegetation and fire history of the Greater Yellowstone Ecosystem is known from low and middle elevations, but little is known about high elevations. Paleoecologic data from Fairy Lake in the Bridger Range, southwestern Montana, provide a new high-elevation record that spans the last 15,000 yr. The records suggest a period of tundra-steppe vegetation prior to ca. 13,700 cal yr BP was followed by open Picea forest at ca. 11,200 cal yr BP. Pinus-Pseudotsuga parkland was present after ca. 9200 cal yr BP, when conditions were warmer/drier than present. It was replaced by mixed-conifer parkland at ca. 5000 cal yr BP. Present-day subalpine forest established at ca. 2800 cal yr BP. Increased avalanche or mass-wasting activity during the early late-glacial period, the Younger Dryas chronozone, and Neoglaciation suggest cool, wet periods. Sites at different elevations in the region show (1) synchronous vegetation responses to late-glacial warming; (2) widespread xerothermic forests and frequent fires in the early-to-middle Holocene; and (3) a trend to forest closure during late-Holocene cooling. Conditions in the Bridger Range were, however, wetter than other areas during the early Holocene. Across the Northern Rockies, postglacial warming progressed from west to east, reflecting range-specific responses to insolation-driven changes in climate.

Mixed coniferous forests are widespread at middle elevations in the Northern Rocky Mountains, yet relatively little is known about their long-term vegetation and fire history. Pollen and charcoal records from Twin Lakes, in the Mission Range of northwestern Montana provide information on mixed-coniferous forest development and fire activity over the last 15,000 years. These data suggest an open parkland and minimal fire activity before 13,500 cal yr BP, consistent with cold, dry conditions. Increases in Pinus pollen after 13,500 cal yr BP indicate a transition to closed forests, and a slight rise in fire activity as conditions warmed and fuel biomass increased. High levels of Artemisia pollen between 10,000 and 6000 cal yr BP suggest an open forest during the early Holocene when conditions were warmer and drier than present. Low-severity fires likely maintained open forest/shrublands but produced little charcoal during this interval. Present-day mixed-coniferous forests were established in the last 6 ka and included forest taxa characteristic of low- (Pseudotsuga-Larix/Pinus ponderosa) and high-severity fire regimes (Picea/Abies). Increased climate variability and anthropogenic burning may have helped maintain heterogeneous, mixed-coniferous forests during the last several millennia when climate conditions became cooler and wetter.

A high-resolution pollen record of the Atlantic rain forest (ARF) biome from the coastal Serra do Tabuleiro mountains of southern Brazil documents an 11,960 yr history of vegetation and climate change. A marked expansion of Weinmannia into the grassland vegetation marks the latter part of the Younger Dryas, reflecting warm and relatively wet conditions. Between 11,490 and 9110 cal yr BP, grasslands became dominant again, indicating a long cold and dry phase, probably in response to the stronger influence of cold South Atlantic seawater and to Antarctic cold fronts. Between 9110 and 2640 cal yr BP, four distinct phases with strong or moderate expansions of different ARF biome taxa were recorded, reflecting warmer and relatively dry conditions with changes in rainfall and length of the annual dry season. After 2640 cal yr BP, the modern ARF biome became established with high amounts of ferns, reflecting somewhat cooler and wetter conditions with a reduced annual dry season. In particular, after 1000 cal yr BP tree ferns increased, reflecting wetter conditions with no dry season.

The Holocene Period for the province of West New Britain, Papua New Guinea, is characterised by periodic catastrophic volcanism. The region is mantled in dense wet tropical rainforest, and has been occupied by people since the Pleistocene. Analyses of peat from two nearby sites within a lowland rainforest environment provide us with a macro-level landscape account of the periodic destruction and recovery of the coastal forests during seven periods of volcanic activity in the latter part (∼2900 yr ago to present) of the Holocene. Radiocarbon dating shows the very close correlation of the peat and tephra layers at both sites, yet the pollen analysis reveals different vegetation communities. These initial results allow us to begin identifying the processes of recovery, and to recognise different ecological pressures placed on vegetation at these neighbouring sites. Evidence of hydrological changes are observed beginning with a marine incursion recorded at Garu Site 3 ∼1360 14C yr B.P. The distinct differences in the vegetation re-establishment and community regeneration rates suggest the greater level of disturbance at Garu Site 1 could be related to the depth of the ashfall, although the proximity of a known human settlement may also be a contributing factor. Of note, palynologically, we found that the fern spore flora is particularly rich and believe it will be useful for ecological interpretation.

A pollen record from Lake Xere Wapo, southeast New Caledonia, is the longest continuous terrestrial record to be recovered from the tropical southwest Pacific and reveals a series of millennial scale changes in vegetation over the last ∼130,000 yr. A comparison of the Lake Xere Wapo record with the key northeast Australian record of Lynch's Crater reveals regional patterns of change. From ∼120,000 to ∼50,000 yr ago the vegetation around Lake Xere Wapo alternated between rainforest and maquis with fire an important disturbance factor. In the last 50,000 yr fire is almost absent from the record and the vegetation assumes a character unprecedented in the preceding 100,000 yr, dominated by Dacrydium and Podocarpus pollen. The most compelling aspect of the comparison with Lynch's Crater is that the much-discussed Araucaria decline at around 45,000 yr ago in northern Queensland is matched by a similar decline in the Lake Xere Wapo record.

A new packrat midden chronology from Playas Valley, southwestern New Mexico, is the first installment of an ongoing effort to reconstruct paleovegetation and paleoclimate in the U.S.A.–Mexico Borderlands. Playas Valley and neighboring basins supported pluvial lakes during full and/or late glacial times. Plant macrofossil and pollen assemblages from nine middens in the Playas Valley allow comparisons of two time intervals: 16,000–10,000 and 4000–0 14C yr B.P. Vegetation along pluvial lake margins consisted of open pinyon–juniper communities dominated by Pinus edulis, Juniperus scopulorum, Juniperus cf. coahuilensis, and a rich understory of C4 annuals and grasses. This summer-flowering understory is also characteristic of modern desert grassland in the Borderlands and indicates at least moderate summer precipitation. P. edulis and J. scopulorum disappeared or were rare in the midden record by 10,670 14C yr B.P. The late Holocene is marked by the arrival of Chihuahuan desert scrub elements and few departures as the vegetation gradually became modern in character. Larrea tridentata appears as late as 2190 14C yr B.P. based on macrofossils, but may have been present as early as 4095 14C yr B.P. based on pollen. Fouquieria splendens, one of the dominant desert species present at the site today, makes its first appearance only in the last millennium. The midden pollen assemblages are difficult to interpret; they lack modern analogs in surface pollen assemblages from stock tanks at different elevations in the Borderlands.

Pollen and lake-level data from Le Locle in the Swiss Jura were used to quantitatively reconstruct climatic parameters for the Younger Dryas event and the first half of the Holocene period. The Younger Dryas cold event at Le Locle was characterized by (i) a general trend toward a slight increase in summer temperature and a decrease in annual precipitation and (ii) a marked drying phase at ca. 11,900 cal yr B.P. that occurred between two wetter ones. Further phases of major deficit in moisture occured at ca. 11,500 cal yr B.P. (Younger Dryas-Holocene transition), 10,800 cal yr B.P., 8700 cal yr B.P., and 6500 cal yr B.P. Climatic parameters reconstructed here suggest that phases of higher lake level developing at ca. 12,500–12,000, 11,750–11,600, 11,200–10,900 (synchronous with the Preboreal oscillation), 10,400–8900, 8400–8300 (possibly related to the 8200 yr event), and 7800–7000 cal yr B.P. coincided with an increase in annual precipitation, a decrease in summer temperature, and a shorter growing season. Conversely, periods of low lake level corresponded to a decrease in annual precipitation, an increase in summer temperature, and a longer growing season. This general pattern could have resulted from alternate southward-northward displacements of the Atlantic Westerly Jet.

The Cascade Range of southwestern Oregon contains some of North America's most diverse forests, but the ecological history of this area is poorly understood. A 7900-yr-long pollen and charcoal record was examined to better understand past changes in vegetation and fire activity in relation to large-scale climate variability. From 7900 to 3500 cal yr BP, the dominance of xerophytic species and the frequent fires are consistent with a climate that was warmer and drier than at present. The period from 3500 cal yr BP to present experienced an abundance of mesophytic taxa and reduced fire frequency, suggesting cooler and wetter conditions. The regional history of Abies indicates that it was most widespread during the late-glacial period; its range contracted during the early Holocene thermal maximum, and it steadily expanded during the middle and late Holocene. In contrast, Pseudotsuga was restricted in range during the glacial period, became abundant at low-elevation sites in the Coast and northern Cascade ranges during the early Holocene, and was more prevalent in southern mid-elevation sites as the climate became cooler and wetter in the late Holocene. The sensitivity of these species to past climate change suggests that biogeographic responses to future conditions will be highly variable in this region.

Avai'o'vuna Swamp, a small coastal wetland in Vava'u, Kingdom of Tonga, produced a 4500-year pollen and sediment record. Results are: (1) a mid-Holocene sea level highstand is confirmed for Tonga between about 4500 and 2600 14C yr B.P.; marine clay contains pollen from mangroves (Rhizophora mangle), coastal forest trees (Barringtonia asiatica and Cocos nucifera), and rainforest trees (Alphitonia, Rhus, Hedycarya and Calophyllum). (2) Microscopic charcoal first appeared at 2600 14C yr B.P., coincident with the arrival of Polynesians. (3) Cocos, Pandanus, Excoecaria, Macaranga, and Elaeocarpaceae pollen reflects the establishment of a mixed coastal-lowland rainforest in the last 2500 years. (4) The loss of Hedycarya, Elaeocarpus, Calophyllum, and Guettarda and the reduction of Terminalia and taxa in the Papilionaceae family by about 1000 years ago may be due to habitat destruction and the loss of dispersal capabilities of some species through the extinction of the two largest pigeons in Tonga.

This multiproxy study on SE Black Sea sediments provides the first detailed reconstruction of vegetation and environmental history of Northern Anatolia between 134 and 119 ka. Here, the glacial–interglacial transition is characterized by several short-lived alternating cold and warm events preceding a meltwater pulse (~ 130.4–131.7 ka). The latter is reconstructed as a cold arid period correlated to Heinrich event 11. The initial warming is evidenced at ~ 130.4 ka by increased primary productivity in the Black Sea, disappearance of ice-rafted detritus, and spreading of oaks in Anatolia. A Younger Dryas-type event is not identifiable. The Eemian vegetation succession corresponds to the main climatic phases in Europe: i) the Quercus–Juniperus phase (128.7–126.4 ka) indicates a dry continental climate; ii) the Ostrya–Corylus–Quercus–Carpinus phase (126.4–122.9 ka) suggests warm summers, mild winters, and high year-round precipitation; iii) the Fagus–Carpinus phase (122.9–119.5 ka) indicates cooling and high precipitation; and iv) increasing Pinus at ~ 121 ka marks the onset of cooler/drier conditions. Generally, pollen reconstructions suggest altitudinal/latitudinal migrations of vegetation belts in Northern Anatolia during the Eemian caused by increased transport of moisture. The evidence for the wide distribution of Fagus around the Black Sea contrasts with the European records and is likely related to climatic and genetic factors.

Paleoecological research has expanded our knowledge of the relationships between climate, fire and vegetation. Fire can be a significant driver of forest composition and structure change, but identifying and quantifying fire regimes has been elusive. Using high-resolution charcoal analysis and pollen analysis we reconstructed a 13,200-year-old fire and vegetation history from Breitenbush Lake, Oregon, located in the central Cascade Range, USA. Our objective was to examine if fire occurrence and severity may have been a driver of Holocene forest-composition change. The data from this study suggests that while fire can create opportunities for successional process to occur, fire events were not significant catalysts for forest change. Instead, most major transitions at Breitenbush Lake occurred during prolonged fire-free intervals. Our results reinforce the view that climate is the major control of vegetation composition change in the Cascade Range.

Charcoal was sampled in four soil profiles at the Mayumbe forest boundary (DRC). Five fire events were recorded and 44 charcoal types were identified. One stratified profile yielded charcoal assemblages around 530 cal yr BP and > 43.5 cal ka BP in age. The oldest assemblage precedes the period of recorded anthropogenic burning, illustrating occasional long-term absence of fire but also natural wildfire occurrences within tropical rainforest. No other charcoal assemblages older than 2500 cal yr BP were recorded, perhaps due to bioturbation and colluvial reworking. The recorded paleofires were possibly associated with short-lived climate anomalies. Progressively dry climatic conditions since ca. 4000 cal yr BP onward did not promote paleofire occurrence until increasing seasonality affected vegetation at the end of the third millennium BP, as illustrated by a fire occurring in mature rainforest that persisted until around 2050 cal yr BP. During a drought episode coinciding with the "Medieval Climate Anomaly", mature rainforest was locally replaced by woodland savanna. Charcoal remains from pioneer forest indicate that fire hampered forest regeneration after climatic drought episodes. The presence of pottery shards and oil-palm endocarps associated with two relatively recent paleofires suggests that the effects of climate variability were amplified by human activities.

A series of environmental changes from late-glacial ice recession through the early Holocene are revealed in a 7000-yr-long record of pollen, charcoal, geochemistry, and stable isotopes from Blacktail Pond, a closed-basin lake in Yellowstone National Park. Prior to 11,500 cal yr BP, cool conditions dominated, fire activity was low, and alpine tundra and Picea parkland grew on the landscape. A step-like climate change to warm summer conditions occurred at 11,500 cal yr BP. In response, fire activity increased facilitating a transition from Picea parkland to closed Pinus forest. From 11,500 to 8280 cal yr BP, warm summers and abundant moisture mostly likely from high winter snowfall supported closed Pinus contorta forests. Cooler drier summer conditions prevailed beginning 8280 cal yr BP due to decreased summer insolation and winter snowpack, and lower parkland developed. The timing of vegetation change in the Blacktail Pond record is similar to other low- and middle-elevation sites in the northern Rocky Mountains during the late-glacial period, suggesting local plant communities responded to regional-scale climate change; however, the timing of vegetation changes was spatially variable during the early and middle Holocene due to the varying influences of strengthened summer monsoons and subtropical high on regional precipitation patterns.

Sedimentary, palynological and diatom data from a dunefield lake deposit in the interior of Vanderlin Island in the Gulf of Carpentaria are presented. Prior to the formation of present perennial lake conditions, the intensified Australian monsoon associated with the early Holocene marine transgression allowed Cyperaceae sedges to colonise the alluvial margins of an expansive salt flat surrounded by an open Eucalyptus woodland. As sea level stabilised between 7500 and 4500 cal yr B.P. coastal dunes ceased to develop allowing dense Melaleuca forest to establish in a Restionaceae swamp. Dune-sand input into the swamp was diminished further as the increasingly dense vegetation prevented fluvial and aeolian transported sand arriving from coastal sources. This same process impounded the drainage basin allowing a perennial lake to form between 5500 and 4000 cal yr B.P. Myriophyllum and other aquatic taxa colonised the lake periphery under the most extensive woodland recorded for the Holocene. The palynological data support an effective precipitation model proposed for northern Australia that suggests more variable conditions in the late Holocene. A more precise measure of effective precipitation change is provided by diatom-based inferences that indicate few changes in lake hydrology. Such interpretations are explained in terms of palynological sensitivity to adjustments in local fire regimes where regional precipitation change may only be recorded indirectly through fire promoting mechanisms, including intensified ENSO periodicity and human impact.

The forests of the Siskiyou Mountains are among the most diverse in North America, yet the long-term relationship among climate, diversity, and natural disturbance is not well known. Pollen, plant macrofossils, and high-resolution charcoal data from Bolan Lake, Oregon, were analyzed to reconstruct a 17,000-yr-long environmental history of high-elevation forests in the region. In the late-glacial period, the presence of a subalpine parkland of Artemisia, Poaceae, Pinus, and Tsuga with infrequent fires suggests cool dry conditions. After 14,500 cal yr B.P., a closed forest of Abies, Pseudotsuga, Tsuga, and Alnus rubra with more frequent fires developed which indicates more mesic conditions than before. An open woodland of Pinus, Quercus, and Cupressaceae, with higher fire activity than before, characterized the early Holocene and implies warmer and drier conditions than at present. In the late Holocene, Abies and Picea were more prevalent in the forest, suggesting a return to cool wet conditions, although fire-episode frequency remained relatively high. The modern forest of Abies and Pseudotsuga and the present-day fire regime developed ca. 2100 cal yr B.P. and indicates that conditions had become slightly drier than before. Sub-millennial-scale fluctuations in vegetation and fire activity suggest climatic variations during the Younger Dryas interval and within the early Holocene period. The timing of vegetation changes in the Bolan Lake record is similar to that of other sites in the Pacific Northwest and Klamath region, and indicates that local vegetation communities were responding to regional-scale climate changes. The record implies that climate-driven millennial- to centennial-scale vegetation and fire change should be considered when explaining the high floristic diversity observed at present in the Siskiyou Mountains.

Pollen analysis from a peat core 7.0 m in length, taken from a bog near Bisoca, in a mid-altitude area of the Buzăului Subcarpathian mountains, is used to reconstruct the postglacial vegetation history of the region. The vegetation record, which is supported by twelve 14C dates, starts at the end of the Late Glacial period. At the Late Glacial/Holocene transition, open vegetation was replaced by forest, suggesting a fast response to climatic warming. The Holocene began with the expansion of Betula, Pinus and Ulmus, followed, after 11,000 cal yr BP, by Fraxinus, Quercus, Tilia and Picea. The rapid expansion of these taxa may be due to their existence in the area during the Late Glacial period. At ca. 9200 cal yr BP, Corylus expanded, reaching a maximum after 7600 cal yr BP. The establishment of Carpinus occurred at ca. 7200 cal yr BP, with a maximum at ca. 5700 cal yr BP. Fagus pollen is regularly recorded after 7800 cal yr BP and became dominant at ca. 2000 cal yr BP. The first indications of human activities appear around 3800 cal yr BP.

The paucity of low- and middle-elevation paleoecologic records in the Northern Rocky Mountains limits our ability to assess current environmental change in light of past conditions. A 10,500-yr-long vegetation, fire and climate history from Lower Decker Lake in the Sawtooth Range provides information from a new region. Initial forests dominated by pine and Douglas-fir were replaced by open Douglas-fir forest at 8420 cal yr BP, marking the onset of warmer conditions than present. Presence of closed Douglas-fir forest between 6000 and 2650 cal yr BP suggests heightened summer drought in the middle Holocene. Closed lodgepole pine forest developed at 2650 cal yr BP and fires became more frequent after 1450 cal yr BP. This shift from Douglas-fir to lodgepole pine forest was probably facilitated by a combination of cooler summers, cold winters, and more severe fires than before. Five drought episodes, including those at 8200 cal yr BP and during the Medieval Climate Anomaly, were registered by brief intervals of lodgepole pine decline, an increase in fire activity, and mistletoe infestation. The importance of a Holocene perspective when assessing the historical range of variability is illustrated by the striking difference between the modern forest and that which existed 3000 yr ago.

A high-resolution pollen record from Lake Teletskoye documents the climate-related vegetation history of the northern Altai Mountain region during the last millennium. Siberian pine taiga with Scots pine, fir, spruce, and birch dominated the vegetation between ca. AD 1050 and 1100. The climate was similar to modern. In the beginning of the 12th century, birch and shrub alder increased. Lowered pollen concentrations and simultaneous peaks in herbs (especially Artemisia and Poaceae), ferns, and charcoal fragments point to colder and more arid climate conditions than before, with frequent fire events. Around AD 1200, regional climate became warmer and more humid than present, as revealed by an increase of Siberian pine and decreases of dry herb taxa and charcoal contents. Climatic conditions were rather stable until ca. AD 1410. An increase of Artemisia pollen may reflect slightly drier climate conditions between AD 1410 and 1560. Increases in Alnus, Betula, Artemisia, and Chenopodiaceae pollen and in charcoal particle contents may reflect further deterioration of climate conditions between AD 1560 and 1810, consistent with the Little Ice Age. After AD 1850 the vegetation gradually approached the modern one, in conjunction with ongoing climate warming.

We reconstructed a 10,500-yr fire and vegetation history of a montane site in the North Cascade Range, Washington State based on lake sediment charcoal, macrofossil and pollen records. High-resolution sampling and abundant macrofossils made it possible to analyze relationships between fire and vegetation. During the early Holocene (> 10,500 to ca. 8000 cal yr BP) forests were subalpine woodlands dominated by Pinus contorta. Around 8000 cal yr BP, P. contorta sharply declined in the macrofossil record. Shade tolerant, mesic species first appeared ca. 4500 cal yr BP. Cupressus nootkatensis appeared most recently at 2000 cal yr BP. Fire frequency varies throughout the record, with significantly shorter mean fire return intervals in the early Holocene than the mid and late Holocene. Charcoal peaks are significantly correlated with an initial increase in macrofossil accumulation rates followed by a decrease, likely corresponding to tree mortality following fire. Climate appears to be a key driver in vegetation and fire regimes over millennial time scales. Fire and other disturbances altered forest vegetation at shorter time scales, and vegetation may have mediated local fire regimes. For example, dominance of P. contorta in the early Holocene forests may have been reinforced by its susceptibility to frequent, stand-replacing fire events.