Fire history in western Patagonia from paired tree-ring fire-scar and charcoal records

Abstract. Fire history reconstructions are typically based on tree ages and tree-ring fire scars or on charcoal in sedimentary records from lakes or bogs, but rarely on both. In this study of fire history in western Patagonia (47–48° S) in southern South America (SSA) we compared three sedimentary charcoal records collected in bogs with tree-ring fire-scar data collected at 13 nearby sample sites. We examined the temporal and spatial correspondence between the two fire proxies and also compared them to published charcoal records from distant sites in SSA, and with published proxy reconstructions of regional climate variability and large-scale climate modes. Two of our three charcoal records show fire activity for the last 4ka yrs and one for the last 11 ka yr. For the last ca. 400 yr, charcoal accumulation peaks tend to coincide with high fire activity in the tree-ring fire scar records, but the charcoal records failed to detect some of the fire activity recorded by tree rings. Potentially, this discrepancy reflects low-severity fires that burn in herbaceous and other fine fuels without depositing charcoal in the sedimentary record. Periods of high fire activity tended to be synchronous across sample areas, across proxy types, and with proxy records of regional climatic variability as well as major climate drivers. Fire activity throughout the Holocene in western Patagonia has responded to regional climate variation affecting a broad region of southern South America that is teleconnected to both tropical- and high-latitude climate drivers – El Nino-Southern Oscillation and the Southern Annular Mode. An early Holocene peak in fire activity pre-dates any known human presence in our study area, and consequently implicates lightning as the ignition source. In contrast, the increased fire activity during the 20th century, which was concomitantly recorded by charcoal from all the sampled bogs and at all fire-scar sample sites, is attributed to human-set fires and is outside the range of variability characteristic of these ecosystems over many centuries and probably millennia.

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Fire history in western Patagonia from paired tree-ring fire-scar and charcoal records

Climate of the Past ◽

10.5194/cp-8-451-2012 ◽

2012 ◽

Vol 8 (2) ◽

pp. 451-466 ◽

Cited By ~ 19

Author(s):

A. Holz ◽

S. Haberle ◽

T. T. Veblen ◽

R. De Pol-Holz ◽

J. Southon

Keyword(s):

South America ◽

Tree Ring ◽

Large Scale ◽

Fire History ◽

Southern Oscillation ◽

Climatic Variability ◽

Regional Climate ◽

Southern South America ◽

Fire Scar ◽

Fire Activity

Abstract. Fire history reconstructions are typically based on tree ages and tree-ring fire scars or on charcoal in sedimentary records from lakes or bogs, but rarely on both. In this study of fire history in western Patagonia (47–48° S) in southern South America (SSA) we compared three sedimentary charcoal records collected in bogs with tree-ring fire-scar data collected at 13 nearby sample sites. We examined the temporal and spatial correspondence between the two fire proxies and also compared them to published charcoal records from distant sites in SSA, and with published proxy reconstructions of regional climate variability and large-scale climate modes. Two of our three charcoal records record fire activity for the last 4 ka yr and one for the last 11 ka yr. For the last ca. 400 yr, charcoal accumulation peaks tend to coincide with high fire activity in the tree-ring fire scar records, but the charcoal records failed to detect some of the fire activity recorded by tree rings. Potentially, this discrepancy reflects low-severity fires that burn in herbaceous and other fine fuels without depositing charcoal in the sedimentary record. Periods of high fire activity tended to be synchronous across sample areas, across proxy types, and with proxy records of regional climatic variability as well as major climate drivers. Fire activity throughout the Holocene in western Patagonia has responded to regional climate variation affecting a broad region of southern South America that is teleconnected to both tropical- and high-latitude climate drivers-El Niño-Southern Oscillation and the Southern Annular Mode. An early Holocene peak in fire activity pre-dates any known human presence in our study area, and consequently implicates lightning as the ignition source. In contrast, the increased fire activity during the 20th century, which was concomitantly recorded by charcoal from all the sampled bogs and at all fire-scar sample sites, is attributed to human-set fires and is outside the range of variability characteristic of these ecosystems over many centuries and probably millennia.

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Climatic controls of Holocene fire patterns in southern South America

Quaternary Research ◽

10.1016/j.yqres.2007.01.012 ◽

2007 ◽

Vol 68 (1) ◽

pp. 28-36 ◽

Cited By ~ 127

Author(s):

Cathy Whitlock ◽

Patricio I. Moreno ◽

Patrick Bartlein

Keyword(s):

South America ◽

Large Scale ◽

Fire History ◽

Regional Climate ◽

Temperature Gradients ◽

Southern South America ◽

Model Simulations ◽

Fire Activity ◽

Southward Shift ◽

Atmospheric Circulation Anomalies

AbstractHolocene fire–climate–vegetation linkages are mostly understood at individual sites by comparing charcoal and pollen records with other paleoenvironmental proxy and model simulations. This scale of reconstruction often obscures detection of large-scale patterns in past fire activity that are related to changes in regional climate and vegetation. A network of 31 charcoal records from southern South America was examined to assess fire history along a transect from subtropic to subantarctic biomes. The charcoal data indicate that fire activity was greater than present at ca. 12,000 cal yr BP and increased further and was widespread at 9500 cal yr BP. Fire activity decreased and became more spatially variable by 6000 cal yr BP, and this trend continued to present. Atmospheric circulation anomalies during recent high-fire years show a southward shift in westerlies, and paleoclimate model simulations and data syntheses suggest that such conditions may have prevailed for millennia in the early Holocene when the pole-to-equator temperature gradients were weaker and annual temperatures were higher than present, in response to orbital-time-scale insolation changes.

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Wildfire activity in rainforests in western Patagonia linked to the Southern Annular Mode

International Journal of Wildland Fire ◽

10.1071/wf10121 ◽

2012 ◽

Vol 21 (2) ◽

pp. 114 ◽

Cited By ~ 32

Author(s):

Andrés Holz ◽

Thomas T. Veblen

Keyword(s):

Fire History ◽

Southern Oscillation ◽

Climatic Variability ◽

Regional Climate ◽

Southern Annular Mode ◽

Strong Increase ◽

Annular Mode ◽

Decadal Scale ◽

In Fire

Increased wildfire activity in relation to future climate warming is likely for temperate rainforest biomes where fire depends on anomalously dry fuel conditions. Tree-ring fire history records were developed from fires scars in western Patagonia, and synchrony in fire activity was examined to determine the role of regional climate variability in promoting fires. Interannual variability in the multicentury fire history records was related to El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and the Southern Annular Mode (SAM). Interannual fire synchrony and decadal-scale trends in wildfires document a strong influence of broad-scale climatic variability on wildfires in western Patagonia. SAM is above average during years of regional drought that coincide with widespread fires. Analyses of contingent interactions of ENSO, PDO and SAM revealed that fire frequencies were greater than expected only when SAM was in its positive phase, regardless of the phase of ENSO and PDO. The fire-enhancing influence of SAM was greatest when PDO was also positive, which indicates Pacific-wide warmer conditions. There is a strong increase in wildfire activity coincident with warming and drying trends during the 20th century and with variability in SAM, which is predicted to continue to be in this fire-conducive phase for the 21st century.

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Fire history on a desert mountain range: Rincon Mountain Wilderness, Arizona, U.S.A.

Canadian Journal of Forest Research ◽

10.1139/x90-208 ◽

1990 ◽

Vol 20 (10) ◽

pp. 1559-1569 ◽

Cited By ~ 245

Author(s):

Christopher H. Baisan ◽

Thomas W. Swetnam

Keyword(s):

Tree Ring ◽

Large Scale ◽

Fire History ◽

Fire Regime ◽

Forest Type ◽

Drought Severity ◽

Mountain Range ◽

Mixed Conifer ◽

The Mean ◽

Mean Fire Interval

Modern fire records and fire-scarred remnant material collected from logs, snags, and stumps were used to reconstruct and analyze fire history in the mixed-conifer and pine forest above 2300 m within the Rincon Mountain Wilderness of Saguaro National Monument, Arizona, United States. Cross-dating of the remnant material allowed dating of fire events to the calendar year. Estimates of seasonal occurrence were compiled for larger fires. It was determined that the fire regime was dominated by large scale (> 200 ha), early-season (May–July) surface fires. The mean fire interval over the Mica Mountain study area for the period 1657–1893 was 6.1 years with a range of 1–13 years for larger fires. The mean fire interval for the mixed-conifer forest type (1748–1886) was 9.9 years with a range of 3–19 years. Thirty-five major fire years between 1700 and 1900 were compared with a tree-ring reconstruction of the Palmer drought severity index (PDSI). Mean July PDSI for 2 years prior to fires was higher (wetter) than average, while mean fire year PDSI was near average. This 490-year record of fire occurrence demonstrates the value of high-resolution (annual and seasonal) tree-ring analyses for documenting and interpreting temporal and spatial patterns of past fire regimes.

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Ocean Salinity Aspects of the Ningaloo Niño

Journal of Climate ◽

10.1175/jcli-d-20-0890.1 ◽

2021 ◽

pp. 1

Author(s):

Yaru Guo ◽

Yuanlong Li ◽

Fan Wang ◽

Yuntao Wei

Keyword(s):

Fresh Water ◽

Large Scale ◽

Southern Oscillation ◽

Regional Climate ◽

Ocean Model ◽

Sea Surface ◽

Sea Surface Salinity ◽

Surface Salinity ◽

Near Surface ◽

Ocean Salinity

AbstractNingaloo Niño – the interannually occurring warming episode in the southeast Indian Ocean (SEIO) – has strong signatures in ocean temperature and circulation and exerts profound impacts on regional climate and marine biosystems. Analysis of observational data and eddy-resolving regional ocean model simulations reveals that the Ningaloo Niño/Niña can also induce pronounced variability in ocean salinity, causing large-scale sea surface salinity (SSS) freshening of 0.15–0.20 psu in the SEIO during its warm phase. Model experiments are performed to understand the underlying processes. This SSS freshening is mutually caused by the increased local precipitation (~68%) and enhanced fresh-water transport of the Indonesian Throughflow (ITF; ~28%) during Ningaloo Niño events. The effects of other processes, such as local winds and evaporation, are secondary (~18%). The ITF enhances the southward fresh-water advection near the eastern boundary, which is critical in causing the strong freshening (> 0.20 psu) near the Western Australian coast. Owing to the strong modulation effect of the ITF, SSS near the coast bears a higher correlation with the El Niño-Southern Oscillation (0.57, 0.77, and 0.70 with Niño-3, Niño-4, and Niño-3.4 indices, respectively) than sea surface temperature (-0.27, -0.42, and -0.35) during 1993-2016. Yet, an idealized model experiment with artificial damping for salinity anomaly indicates that ocean salinity has limited impact on ocean near-surface stratification and thus minimal feedback effect on the warming of Ningaloo Niño.

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Comparison of 20th century and pre-industrial climate over South America in regional model simulations

Climate of the Past ◽

10.5194/cp-8-1599-2012 ◽

2012 ◽

Vol 8 (5) ◽

pp. 1599-1620 ◽

Cited By ~ 6

Author(s):

S. Wagner ◽

I. Fast ◽

F. Kaspar

Keyword(s):

South America ◽

Greenhouse Gas ◽

Atmospheric Circulation ◽

20Th Century ◽

Climate Model ◽

Regional Climate ◽

Regional Model ◽

Andes Mountains ◽

Southern South America ◽

The Andes

Abstract. In this study, we assess how the anthropogenically induced increase in greenhouse gas concentrations affects the climate of central and southern South America. We utilise two regional climate simulations for present day (PD) and pre-industrial (PI) times. These simulations are compared to historical reconstructions in order to investigate the driving processes responsible for climatic changes between the different periods. The regional climate model is validated against observations for both re-analysis data and GCM-driven regional simulations for the second half of the 20th century. Model biases are also taken into account for the interpretation of the model results. The added value of the regional simulation over global-scale modelling relates to a better representation of hydrological processes that are particularly evident in the proximity of the Andes Mountains. Climatic differences between the simulated PD minus PI period agree qualitatively well with proxy-based temperature reconstructions, albeit the regional model overestimates the amplitude of the temperature increase. For precipitation the most important changes between the PD and PI simulation relate to a dipole pattern along the Andes Mountains with increased precipitation over the southern parts and reduced precipitation over the central parts. Here only a few regions show robust similarity with studies based on empirical evidence. However, from a dynamical point-of-view, atmospheric circulation changes related to an increase in high-latitude zonal wind speed simulated by the regional climate model are consistent with numerical modelling studies addressing changes in greenhouse gas concentrations. Our results indicate that besides the direct effect of greenhouse gas changes, large-scale changes in atmospheric circulation and sea surface temperatures also exert an influence on temperature and precipitation changes in southern South America. These combined changes in turn affect the relationship between climate and atmospheric circulation between PD and PI times and should be considered for the statistical reconstruction of climate indices calibrated within present-day climate data.

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Synchronous combined effects of fishing and climate within a demersal community

ICES Journal of Marine Science ◽

10.1093/icesjms/fss181 ◽

2012 ◽

Vol 70 (2) ◽

pp. 319-328 ◽

Cited By ~ 25

Author(s):

Antoni Quetglas ◽

Francesc Ordines ◽

Manuel Hidalgo ◽

Sebastià Monserrat ◽

Susana Ruiz ◽

...

Keyword(s):

Climate Variability ◽

Age Structure ◽

Large Scale ◽

Southern Oscillation ◽

Climatic Variability ◽

Early Period ◽

Combined Effects ◽

Population Fluctuations ◽

Fishing Activity ◽

The Mediterranean

Abstract Quetglas, A., Ordines, F., Hidalgo, M., Monserrat, S., Ruiz, S., Amores, Á., Moranta, J., and Massutí, E. 2013. Synchronous combined effects of fishing and climate within a demersal community. – ICES Journal of Marine Science, 70: 319–328. Accumulating evidence shows that fishing exploitation and environmental variables can synergistically affect the population dynamics of exploited populations. Here, we document an interaction between fishing impact and climate variability that triggered a synchronic response in the population fluctuations of six exploited species in the Mediterranean from 1965–2008. Throughout this period, the fishing activity experienced a sharp increase in fishing effort, which caused all stocks to shift from an early period of underexploitation to a later period of overexploitation. This change altered the population resilience of the stocks and brought about an increase in the sensitivity of its dynamics to climate variability. Landings increased exponentially when underexploited but displayed an oscillatory behaviour once overexploited. Climatic indices, related to the Mediterranean mesoscale hydrography and large-scale north Atlantic climatic variability, seemed to affect the species with broader age structure and longer lifespan, while the global-scale El Niño Southern Oscillation index (ENSO) positively influenced the population abundances of species with a narrow age structure and short lifespan. The species affected by ENSO preferentially inhabit the continental shelf, suggesting that Mediterranean shelf ecosystems are sensitive to the hydroclimatic variability linked to global climate.

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Juniper Tree-Ring Data from the Kuramin Range (Northern Tajikistan) Reveals Changing Summer Drought Signals in Western Central Asia

Forests ◽

10.3390/f10060505 ◽

2019 ◽

Vol 10 (6) ◽

pp. 505 ◽

Cited By ~ 3

Author(s):

Feng Chen ◽

Tongwen Zhang ◽

Andrea Seim ◽

Shulong Yu ◽

Ruibo Zhang ◽

...

Keyword(s):

Central Asia ◽

Tree Ring ◽

Large Scale ◽

Southern Oscillation ◽

Severity Index ◽

Drought Severity ◽

Summer Drought ◽

Tree Ring Chronology ◽

Tree Ring Data ◽

June July

Coniferous forests cover the mountains in many parts of Central Asia and provide large potentials for dendroclimatic studies of past climate variability. However, to date, only a few tree-ring based climate reconstructions exist from this region. Here, we present a regional tree-ring chronology from the moisture-sensitive Zeravshan juniper (Juniperus seravschanica Kom.) from the Kuramin Range (Tajikistan) in western Central Asia, which is used to reveal past summer drought variability from 1650 to 2015 Common Era (CE). The chronology accounts for 40.5% of the variance of the June–July self-calibrating Palmer Drought Severity Index (scPDSI) during the instrumental period (1901 to 2012). Seven dry periods, including 1659–1696, 1705–1722, 1731–1741, 1758–1790, 1800–1842, 1860–1875, and 1931–1987, and five wet periods, including 1742–1752, 1843–1859, 1876–1913, 1921–1930, and 1988–2015, were identified. Good agreements between drought records from western and eastern Central Asia suggest that the PDSI records retain common drought signals and capture the regional dry/wet periods of Central Asia. Moreover, the spectral analysis indicates the existence of centennial (128 years), decadal (24.3 and 11.4 years), and interannual (8.0, 3.6, 2.9, and 2.0 years) cycles, which may be linked with climate forces, such as solar activity and El Niño-Southern Oscillation (ENSO). The analysis between the scPDSI reconstruction and large-scale atmospheric circulations during the reconstructed extreme dry and wet years can provide information about the linkages of extremes in our scPDSI record with the large-scale ocean–atmosphere–land circulation systems.

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