LATE HOLOCENE FIRE AND AGRICULTURE IN THE COPAN VALLEY, HONDURAS

Pollen and charcoal analysis of a 5.3-m sediment core from Aguada Petapilla, a peat bog, provides evidence of late Holocene vegetation and fire history in the Copan Valley, Honduras. Low concentration and preservation problems characterized the pollen flora, but there are taxa present indicative of major agricultural trends, including Zea mays. Microscopic charcoal fragments are well represented and record continued burning in the region since the lowest level of the core (5700 B.P. [3750 B.C.]). Presence of Zea indicates that maize farming was initiated by as early as 2300 B.C. Three peaks in charcoal-fragment frequencies occur in periods centered approximately at 900 B.C., 400 B.C., and A.D. 600. Fires in this relatively dry region of the southern Maya Lowlands (whose mean annual rainfall is about 1,400 mm) could have resulted from natural forest fires or human agricultural clearing at any time in the Holocene. This contrasts with wetter areas of tropical Central and South America (mean annual rainfall of about 2,500–4,000 mm) where significant climatic drying is required to ignite primary tropical forest.

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Late Holocene vegetation and environments of the Mersey Valley, Tasmania

Australian Journal of Botany ◽

10.1071/bt06010 ◽

2007 ◽

Vol 55 (1) ◽

pp. 74 ◽

Cited By ~ 9

Author(s):

Patrick T. Moss ◽

Ian Thomas ◽

Michael Macphail

Keyword(s):

Late Holocene ◽

Fire History ◽

Climatic Factors ◽

Regional Climate ◽

Sedimentation Rates ◽

Exotic Plant ◽

Charcoal Analysis ◽

Climate Signal ◽

The Past ◽

The Impact

A record of vegetation and environmental change over the past 3000 years was obtained through pollen and charcoal analysis of sediments from a grassy plain in the Mersey Valley, Tasmania. The results tentatively suggest that Aborigines had an impact on the environment of the Mersey Valley, although the scale of the impact is difficult to quantify owing to complexities associated with the fire history and sedimentary processes. In addition, a strong regional climate signal (drier late Holocene environments) was observed, suggesting that both anthropogenic and climatic factors are required to explain pre-European environments. The study also showed the dramatic impact European settlers had on the Australian environment, with massive land clearance, introduction of exotic plant types and increased sedimentation rates.

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The Late Holocene forest fire history in continuous permafrost zone of Central Siberia

10.5194/egusphere-egu21-5509 ◽

2021 ◽

Author(s):

Elena Novenko ◽

Natalia Mazei ◽

Dmitry Kupryanov ◽

Anatoly Prokushkin

Keyword(s):

Return Period ◽

Forest Fires ◽

Late Holocene ◽

Fire History ◽

Forest Ecosystems ◽

Fire Frequency ◽

Permafrost Zone ◽

Central Siberia ◽

Free Interval ◽

Continuous Permafrost

Understanding the long-term fire history of larch forests in the permafrost zone of Central Siberia is essential for an assessment of the possible responses and feedbacks of forest ecosystems to climate change. The multi-proxy record from the area of the Evenkian field station of the Sukachev Institute of Forest SB RAS, located in the middle part of the Lower Tunguska river basin provides important new data on the fire frequency, vegetation changes and paludification dynamics in the Central Evenkia over the last 3.5 ka BP. The new results of radiocarbon dating, loss on ignition, plant macrofossil and macro charcoal analyses from a sediment core taken in the waterlogged larch forest (N 64&#176;09'56.1" E 100&#176;31'43.9") are presented.The obtained data have shown that fires were an important factor in the evolution of forest ecosystems in this continuous permafrost regions and acted as a trigger for the paludification process in the study area. The reconstruction of fire frequency demonstrated that the fire return period in the warm epochs of the late Holocene (3.6-2.7 ka BP, 1.5-0.7 ka BP, including the Medieval Climate Anomaly) varied from 115 to 150 years, and increased to 275-300 years during the periods of cooling (2.7-1.5 ka BP; the Little Ice Age, 0.7-0.15 ka BP). We suggested that the shorter and possibly colder summers during the cold epochs led to a decreased evaporation and a rise of ground moisture in many habitats, which was unfavorable for the occurrence and extension of forest fires. During the last 200 years the frequency of forest fires in the study area increased significantly, the fire return period reduced to a minimum value for the entire period under consideration (i.e. the last 3.5 ka BP) and reached 80 years. The fire free interval revealed from the macro charcoal analyses for the last 200 years is close to the average fire free interval reconstructed by dendrochronological data from the study area for the same period. The low human impact on forest ecosystems due to remote location of study area from settlements and mining regions suggests the natural causes of these fires.This work was supported by the Russian Science Foundation, project &#8470; 20-17-00043.

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Postglacial Vegetation and Fire History in the Chirripó Páramo of Costa Rica

Quaternary Research ◽

10.1006/qres.1993.1061 ◽

1993 ◽

Vol 40 (1) ◽

pp. 107-116 ◽

Cited By ~ 68

Author(s):

Sally P. Horn

Keyword(s):

Costa Rica ◽

Late Holocene ◽

Fire History ◽

Charcoal Analysis ◽

Climatic Warming ◽

Lowland Forest ◽

Fire Activity ◽

Ice Retreat ◽

The Impact ◽

Cordillera De Talamanca

AbstractPollen and charcoal analysis of a 5.6-m sediment core from Lago de las Morrenas (9°29′N, 83°29′W; 3480 m) provides evidence of postglacial vegetation and fire history in the highlands of the Cordillera de Talamanca, Costa Rica. The site is presently surrounded by treeless páramo vegetation and apparently has been so since deglaciation about 10,000 yr B.P. Pollen spectra suggest no pronounced changes in vegetation since ice retreat. Fires set by people or lightning have burned the páramo repeatedly, with fire activity probably highest during the late Holocene, but these fires have not carved páramo from forest. Pollen percentages for Gramineae and other páramo taxa decline upward, whereas percentages for certain subalpine, lower montane, and lowland forest taxa increase slightly; these changes may reflect the impact of prehistoric human activity or slight upslope migrations of forest taxa owing to climatic warming. There is no clear evidence of higher timberlines during the mid-Holocene.

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A 14,300-year-long record of fire–vegetation–climate linkages at Battle Ground Lake, southwestern Washington

Quaternary Research ◽

10.1016/j.yqres.2008.05.002 ◽

2008 ◽

Vol 70 (2) ◽

pp. 251-264 ◽

Cited By ~ 42

Author(s):

Megan K. Walsh ◽

Cathy Whitlock ◽

Patrick J. Bartlein

Keyword(s):

Late Holocene ◽

Fire History ◽

Late Glacial ◽

Tsuga Heterophylla ◽

Fire Season ◽

Charcoal Analysis ◽

Vegetation Shifts ◽

Late Glacial Period ◽

High Severity ◽

History Record

AbstractHigh-resolution macroscopic charcoal analysis was used to reconstruct a 14,300-year-long fire history record from the lower Columbia River Valley in southwestern Washington, which was compared to a previous vegetation reconstruction for the site. In the late-glacial period (ca. 14,300-13,100 cal yr BP), Pinus/Picea-dominated parkland supported little to no fire activity. From the late-glacial to the early Holocene (ca. 13,100-10,800 cal yr BP), Pseudotsuga/Abies-dominated forest featured more frequent fire episodes that burned mostly woody vegetation. In the early to middle Holocene (ca. 10,800-5200 cal yr BP), Quercus-dominated savanna was associated with frequent fire episodes of low-to-moderate severity, with an increased herbaceous (i.e., grass) charcoal content. From the middle to late Holocene (ca. 5200 cal yr BP to present), forest dominated by Pseudotsuga, Thuja-type, and Tsuga heterophylla supported less frequent, but mostly large or high-severity fire episodes. Fire episodes were least frequent, but were largest or most severe, after ca. 2500 cal yr BP. The fire history at Battle Ground Lake was apparently driven by climate, directly through the length and severity of the fire season, and indirectly through climate-driven vegetation shifts, which affected available fuel biomass.

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Quantification of southwest China rainfall during the 8.2 ka BP event with response to North Atlantic cooling

Climate of the Past ◽

10.5194/cp-12-1583-2016 ◽

2016 ◽

Vol 12 (7) ◽

pp. 1583-1590 ◽

Cited By ~ 4

Author(s):

Yuhui Liu ◽

Chaoyong Hu

Keyword(s):

High Resolution ◽

Southwest China ◽

East Asian Monsoon ◽

Moving Average ◽

Ice Core ◽

Scale Model ◽

Annual Rainfall ◽

Transport Pathway ◽

Mean Annual Rainfall ◽

Monsoon Area

Abstract. The 8.2 ka BP event could provide important information for predicting abrupt climate change in the future. Although published records show that the East Asian monsoon area responded to the 8.2 ka BP event, there is no high-resolution quantitative reconstructed climate record in this area. In this study, a reconstructed 10-year moving average annual rainfall record in southwest China during the 8.2 ka BP event is presented by comparing two high-resolution stalagmite δ18O records from Dongge cave and Heshang cave. This decade-scale rainfall reconstruction is based on a central-scale model and is confirmed by inter-annual monitoring records, which show a significant positive correlation between the regional mean annual rainfall and the drip water annual average δ18O difference from two caves along the same monsoon moisture transport pathway from May 2011 to April 2014. Similar trends between the reconstructed rainfall and the stalagmite Mg ∕ Ca record, another proxy of rainfall, during the 8.2 ka BP period further increase the confidence of the quantification of the rainfall record. The reconstructed record shows that the mean annual rainfall in southwest China during the central 8.2 ka BP event is less than that of present (1950–1990) by ∼  200 mm and decreased by ∼  350 mm in ∼  70 years experiencing an extreme drying period lasting for ∼  50 years. Comparison of the reconstructed rainfall record in southwest China with Greenland ice core δ18O and δ15N records suggests that the reduced rainfall in southwest China during the 8.2 ka BP period was coupled with Greenland cooling with a possible response rate of 110 ± 30 mm °C−1.

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Modelling monthly runoff generation processes following land use changes: groundwater–surface runoff interactions

Hydrology and Earth System Sciences ◽

10.5194/hess-8-903-2004 ◽

2004 ◽

Vol 8 (5) ◽

pp. 903-922 ◽

Cited By ~ 13

Author(s):

M. Bari ◽

K. R. J. Smettem

Keyword(s):

Land Use ◽

Water Balance ◽

Surface Runoff ◽

Land Use Changes ◽

Annual Rainfall ◽

Rainfall Runoff ◽

Runoff Generation ◽

Mean Annual Rainfall ◽

Monthly Runoff ◽

Stream Bed

Abstract. A conceptual water balance model is presented to represent changes in monthly water balance following land use changes. Monthly rainfall–runoff, groundwater and soil moisture data from four experimental catchments in Western Australia have been analysed. Two of these catchments, "Ernies" (control, fully forested) and "Lemon" (54% cleared) are in a zone of mean annual rainfall of 725 mm, while "Salmon" (control, fully forested) and "Wights" (100% cleared) are in a zone with mean annual rainfall of 1125 mm. At the Salmon forested control catchment, streamflow comprises surface runoff, base flow and interflow components. In the Wights catchment, cleared of native forest for pasture development, all three components increased, groundwater levels rose significantly and stream zone saturated area increased from 1% to 15% of the catchment area. It took seven years after clearing for the rainfall–runoff generation process to stabilise in 1984. At the Ernies forested control catchment, the permanent groundwater system is 20 m below the stream bed and so does not contribute to streamflow. Following partial clearing of forest in the Lemon catchment, groundwater rose steadily and reached the stream bed by 1987. The streamflow increased in two phases: (i) immediately after clearing due to reduced evapotranspiration, and (ii) through an increase in the groundwater-induced stream zone saturated area after 1987. After analysing all the data available, a conceptual monthly model was created, comprising four inter-connecting stores: (i) an upper zone unsaturated store, (ii) a transient stream zone store, (ii) a lower zone unsaturated store and (iv) a saturated groundwater store. Data such as rooting depth, Leaf Area Index, soil porosity, profile thickness, depth to groundwater, stream length and surface slope were incorporated into the model as a priori defined attributes. The catchment average values for different stores were determined through matching observed and predicted monthly hydrographs. The observed and predicted monthly runoff for all catchments matched well with coefficients of determination (R2) ranging from 0.68 to 0.87. Predictions were relatively poor for: (i) the Ernies catchment (lowest rainfall, forested), and (ii) months with very high flows. Overall, the predicted mean annual streamflow was within ±8% of the observed values. Keywords: monthly streamflow, land use change, conceptual model, data-based approach, groundwater

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A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years

Climate of the Past ◽

10.5194/cp-12-189-2016 ◽

2016 ◽

Vol 12 (2) ◽

pp. 189-200 ◽

Cited By ~ 22

Author(s):

C. S. M. Turney ◽

R. T. Jones ◽

C. Fogwill ◽

J. Hatton ◽

A. N. Williams ◽

...

Keyword(s):

Southern Hemisphere ◽

Global Climate Change ◽

Late Holocene ◽

Global Climate ◽

Falkland Islands ◽

The Core ◽

Atmosphere System ◽

Westerly Winds ◽

Ocean Atmosphere ◽

Southern Hemisphere Westerly Winds

Abstract. Southern Hemisphere westerly airflow has a significant influence on the ocean–atmosphere system of the mid- to high latitudes with potentially global climate implications. Unfortunately, historic observations only extend back to the late 19th century, limiting our understanding of multi-decadal to centennial change. Here we present a highly resolved (30-year) record of past westerly wind strength from a Falkland Islands peat sequence spanning the last 2600 years. Situated within the core latitude of Southern Hemisphere westerly airflow (the so-called furious fifties), we identify highly variable changes in exotic pollen and charcoal derived from South America which can be used to inform on past westerly air strength. We find a period of high charcoal content between 2000 and 1000 cal. years BP, associated with increased burning in Patagonia, most probably as a result of higher temperatures and stronger westerly airflow. Spectral analysis of the charcoal record identifies a pervasive ca. 250-year periodicity that is coherent with radiocarbon production rates, suggesting that solar variability has a modulating influence on Southern Hemisphere westerly airflow. Our results have important implications for understanding global climate change through the late Holocene.

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Precipitation as driver of carbon fluxes in 11 African ecosystems

Biogeosciences Discussions ◽

10.5194/bgd-5-4071-2008 ◽

2008 ◽

Vol 5 (5) ◽

pp. 4071-4105 ◽

Cited By ~ 14

Author(s):

L. Merbold ◽

J. Ardö ◽

A. Arneth ◽

R. J. Scholes ◽

Y. Nouvellon ◽

...

Keyword(s):

Land Surface ◽

Ecosystem Respiration ◽

Carbon Assimilation ◽

Vapour Pressure Deficit ◽

Sub Saharan Africa ◽

Annual Rainfall ◽

C3 Plants ◽

Water Vapour Pressure ◽

Mean Annual Rainfall ◽

Sub Saharan

Abstract. This study reports carbon and water fluxes between the land surface and atmosphere in eleven different ecosystems types in Sub-Saharan Africa, as measured using eddy covariance (EC) technology in the first two years of the CarboAfrica network operation. The ecosystems for which data were available ranged in mean annual rainfall from 320 mm (Sudan) to 1150 mm (The Republic of Congo) and include a spectrum of vegetation types (or land cover) (open savannas, woodlands, croplands and grasslands). Given the shortness of the record, the EC data were analysed across the network rather than longitudinally at sites, in order to understand the driving factors for ecosystem respiration and carbon assimilation, and to reveal the different water use strategies in these highly seasonal environments. Values for maximum net carbon assimilation rates (photosynthesis) ranged from 12 μmol CO2 m−2 s−1 in a dry, open Acacia savanna (C3-plants) up to 40 μmol CO2 m−2 s−1 for a tropical moist grassland. Maximum carbon assimilation rates were highly correlated with mean annual rainfall (R2=0.89). Maximum photosynthetic uptake rates were positively related to satellite-derived fAPAR. Ecosystem respiration was dependent on temperature at all sites, and was additionally dependent on soil water content at sites receiving less than 1000 mm of rain per year. All included ecosystems, except the Congolese grassland, showed a strong decrease in 30-min assimilation rates with increasing water vapour pressure deficit above 2.0 kPa.

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