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The coastlines of the southwestern Pacific are dynamic environments that have been repeatedly reshaped by tectonic forces as well as changing global climate and sea level. It has been theorized that much of the north coast of New Guinea was sparsely inhabited until stabilization of coastal flats fallowing the Mid-Holocene Thermal Maximum and resulting marine high stand. We report on environmental proxy indicators measured in core samples taken near modern day Aitape, Papua New Guinea. These cores record the formation of a large lagoonal system on the modern coastal flats by 5800 cal BP. This lagoon infilled over the next several 1000 years as sea level dropped, with the modern coastal flats stabilizing by 1400 cal BP. A charcoal record spanning the period between 6200 and 1400 cal BP documents substantial increases in influx between ~6200 and 6000 cal BP and particularly from ~3000 to 2600 cal BP. Comparison to regional charcoal and ENSO records suggests that increasing aridity and ENSO intensity may drive regional patterning in fire records, however, localized charcoal records are also heavily influenced by human activity. Between 3000 and 2600 cal BP, forest management practices in the Aitape area, currently focused on tree crops and horticulture characterized by long fallowing and limited burning, shifted to a regime characterized by large scale forest clearance and shorter fallowing. We hypothesize that increasing population driven by abundant Mid-Holocene lagoonal resources may have been difficult to maintain as lagoons infilled and climate became more variable, leading to horticultural intensification. [ABSTRACT FROM AUTHOR]

The current fires raging across Indonesia are emitting more carbon than the annual fossil fuel emissions of Germany or Japan, and the fires are still consuming vast tracts of rainforest and peatlands. The National Interagency Fire Center (www.nifc.gov) notes that 2015 is one worst fire years on record in the U.S., where more than 9 million acres burned -- equivalent to the combined size of Massachusetts and New Jersey. The U.S. and Indonesian fires have already displaced tens of thousands of people, and their impacts on ecosystems are still unclear. In the case of Indonesia, the burning peat is destroying much of the existing soil, with unknown implications for the type of vegetation regrowth. Such large fires result from a combination of fire management practices, increasing anthropogenic land use, and a changing climate.The expected increase in fire activity in the upcoming decades has led to a surge in research trying to understand their causes, the factors that may have influenced similar times of fire activity in the past, and the implications of such fire activity in the future. Multiple types of complementary data provide information on the impacts of current fires and the extent of past fires. The wide array of data encompasses different spatial and temporal resolutions (Figure 1) and includes fire proxy information such as charcoal and tree ring fire scars, observational records, satellite products, modern emissions data, fire models within global land cover and vegetation models, and sociodemographic data for modeling past human land use and ignition frequency. Any single data type is more powerful when combined with another source of information. Merging model and proxy data enables analyses of how fire activity modifies vegetation distribution, air and water quality, and proximity to cities; these analyses in turn support land management decisions relating to conservation and development.

A 3300 year-long reconstruction of paleoenvironmental moisture conditions was constructed from a sediment core from North Gate Bog (NGB) in the northern section of Range Creek Canyon within the Colorado Plateau. The methods used to analyze the record include loss on ignition (LOI), magnetic susceptibility (MS), elemental analysis with X-ray fluorescence (XRF), charcoal influx, isotopic analysis, elemental ratios and pollen percentages, influx, and ratios. This study adds two new insights to the paleoenvironmental record of the northern section of the Colorado Plateau. First, four climatic zones were established. Zone 1 (3300–2750 cal yr BP) had 100-year wet to dry variations with droughts recorded from 3300–3200, 3000–2900, and 2800–2700 cal yr BP. Zone 2 (2750–1600 cal yr BP) had an overall dry period with an 800-year transition to increased warmth and winter moisture. Zone 3 (1600–850 cal yr BP) had an overall warm, wet, summer precipitation climate conducive to the establishment of Zea Mays and Pinus edulis, two staple foods of the Fremont culture. The Medieval Climate Anomaly (MCA) registered warm and wet in this part of the Colorado Plateau. Zone 4 (850–0 cal yr BP) had a sharp transition to a drier climate from 850 to 400 cal yr BP. During the Little Ice Age (LIA), wetter climate taxon increases such as Artemisia, Cyperaceae, and Pinus edulis. The second overall finding in this study was that NGB was a place of human activity including Fremont farming. The identification of a Zea mays pollen grain confirms the archeological presumptions that this higher elevation site was used to farm corn along with other sites in Range Creek Canyon (RCC). The post Fremont occupation period was marked by a sharp increase in organic material and a return of pinyon-juniper woodlands. [ABSTRACT FROM AUTHOR]

In contrast to temperate regions, relationships between basin characteristics (e.g., type/size) and fossil pollen archives have received little attention in Amazonia. Here, we compare fossil pollen records of a small palm swamp (Cuatro Vientos; CV) and a nearby large lake (Laguna Chaplin, LCH) in Bolivian Amazonia, demonstrating that palm swamps can yield Quaternary pollen archives recording the history of terrestrial vegetation beyond the basin margin, rather than merely a history of localized swamp vegetation dynamics. The pollen assemblages from these two contrasting basins display remarkable agreement throughout their late Quaternary history, indicating past drier climates supported savanna landscape during the last glacial maximum (LGM; 24,000–18,000 cal yr BP) and savanna/semideciduous forest mosaic during the middle Holocene (7000-4750 cal yr BP) at both regional (inferred from LCH) and local (inferred from CV) spatial scales. Additionally, the local-scale catchment of CV and the basin's proximity to the riverine forests of the Río Paraguá enables exploration of the extent of gallery/riverine forests during the LGM and middle Holocene. We show that, between 24,000–4000 cal yr BP, riverine/gallery rainforests were substantially reduced compared with present, challenging the hypothesis that gallery rainforests were important refugia for rainforest species during the drier LGM and middle Holocene. [ABSTRACT FROM AUTHOR]

Global climate change poses significant threats to the Caribbean islands. Yet, little is known about the long-term disturbance regimes in island ecosystems. This research investigates 2000 yr of natural and anthropogenic fire disturbance through the analysis of a latitudinal transect of sediment records from coastal salt ponds in the British Virgin Islands (BVI). The two research objectives in this study are (1) to determine the fire regime history for the BVI over the last 2000 yr and (2) to explore ecological impacts from anthropogenic landscape modification pre- and post-European settlement. The magnitude of anthropogenic landscape modification, including the introduction of agriculture, was investigated through a multiproxy approach using sedimentary records of fossil pollen and charcoal. Our results suggest fire regimes from Belmont Pond, Thatch Island, and Skeleton Pond have been influenced by human activity, particularly during the postsettlement era, from 500 cal yr BP to modern. Our results suggest that fire regimes during the Medieval Climate Anomaly were responding to changes in climate via dominant atmospheric drivers. The presettlement fire regimes from these islands suggest that fires occurred every 90 to 120 yr. This research represents a significant data contribution to a region with little disturbance and vegetation data available. [ABSTRACT FROM AUTHOR]

In the southern Amazon relationships have been established among drought, human activities that cause forest loss, fire, and smoke emissions. We explore the effects of recent drought on fire, forest loss, and atmospheric visibility in lowland Bolivia. To assess human influence on fire, we consider climate, fire and vegetation dynamics in an area largely excluded from human activities since 1979, Noel Kempff Mercado National Park (NK) in northeastern Bolivia. We use data from five sources: the Moderate Resolution Imaging Spectroradiometer Collection 6 active fire product (2001–2015) (MODIS C6), Global Fire Weather Database data (1982–2015) (GFWED), MODIS land-cover data (2001–2010), MODIS forest loss data (2000–2012), and extinction coefficient derived from horizontal visibility data from the World Meteorological Organization (WMO)-level surface stations (1973–2015), which is affected by smoke and acts as a proxy for regional fire activity. In lowland Bolivia from 2001–2015, interannual Drought Code (DC) variability was linked to fire activity, while from 1982–2015, interannual DC variability was linked to Bext visibility data. From 2001–2015, the regional extinction coefficient for the southwestern Amazon Bext and MODIS C6 active fire data for lowland Bolivia captured fire seasonality, and covaried between low and high fire years. Consistent with previous studies, our results suggest the extinction coefficient Bext can be used as a longer-term proxy of regional fire activity in southwestern Amazonia. Overall, our study found drought conditions were the dominant control on interannual fire variability in lowland Bolivia, and fires within NK were limited to the cerrado and seasonally-inundated wetland biomes. Our results suggest lowland Bolivia tropical forests were susceptible to human activities that may have amplified fire during times of drought. Human activities and drought need to be considered in future projections of southern Amazonia fire, in regard to carbon emissions and global climate. [ABSTRACT FROM AUTHOR]