Catastrophic Bushfires, Indigenous Fire Knowledge and Reframing Science in Southeast Australia.

The catastrophic 2019/2020 Black Summer bushfires were the worst fire season in the recorded history of Southeast Australia. These bushfires were one of several recent global conflagrations across landscapes that are homelands of Indigenous peoples, homelands that were invaded and colonised by European nations over recent centuries. The subsequent suppression and cessation of Indigenous landscape management has had profound social and environmental impacts. The Black Summer bushfires have brought Indigenous cultural burning practices to the forefront as a potential management tool for mitigating climate-driven catastrophic bushfires in Australia. Here, we highlight new research that clearly demonstrates that Indigenous fire management in Southeast Australia produced radically different landscapes and fire regimes than what is presently considered “natural”. We highlight some barriers to the return of Indigenous fire management to Southeast Australian landscapes. We argue that to adequately address the potential for Indigenous fire management to inform policy and practice in managing Southeast Australian forest landscapes, scientific approaches must be decolonized and shift from post-hoc engagement with Indigenous people and perspectives to one of collaboration between Indigenous communities and scientists

Charcoal analysis for temperature reconstruction with infrared spectroscopy

The duration and maximum combustion temperature of vegetation fires are important fire properties with implications for ecology, hydrology, hazard potential, and many other processes. Directly measuring maximum combustion temperature during vegetation fires is difficult. However, chemical transformations associated with temperature are reflected in the chemical properties of charcoals (a by-product of fire). Therefore, charcoal could be used indirectly to determine the maximum combustion temperature of vegetation fires with application to palaeoecological charcoal records. To evaluate the reliability of charcoal chemistry as an indicator of maximum combustion temperature, we studied the chemical properties of charcoal formed through two laboratory methods at measured temperatures. Using a muffle furnace, we generated charcoal from the woody material of ten different tree and shrub species at seven distinct peak temperatures (from 200°C to 800°C in 100°C increments). Additionally, we simulated more natural combustion conditions by burning woody material and leaves of four tree species in a combustion facility instrumented with thermocouples, including thermocouples inside and outside of tree branches. Charcoal samples generated in these controlled settings were analyzed using Fourier Transform Infrared (FTIR) spectroscopy to characterize their chemical properties. The Modern Analogue Technique (MAT) was employed on FTIR spectra of muffle furnace charcoal to assess the accuracy of inferring maximum pyrolysis temperature. The MAT model temperature matching accuracy improved from 46% for all analogues to 81% when including ±100°C. Furthermore, we used MAT to compare charcoal created in the combustion facility with muffle furnace charcoal. Our findings indicate that the spectra of charcoals generated in a combustion facility can be accurately matched with muffle furnace-created charcoals of similar temperatures using MAT, and the accuracy improved when comparing the maximum pyrolysis temperature from muffle furnace charcoal with the maximum inner temperature of the combustion facility charcoal. This suggests that charcoal produced in a muffle furnace may be representative of the inner maximum temperatures for vegetation fire-produced charcoals

Relating pollen representation to an evolving Amazonian landscape between the last glacial maximum and late Holocene

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/semi-deciduous 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

Climate change and cultural resilience in late pre-Columbian Amazonia

The long term response of ancient societies to climate change has been a matter of global debate. Until recently, the lack of integrative studies between archaeological, palaeoecological, and palaeoclimatological data had prevented an evaluation of the relationship between climate change, distinct subsistence strategies, and cultural transformations across the largest rainforest of the world, Amazonia. Here, we review the most relevant cultural changes seen in the archaeological record of six different regions within Greater Amazonia during late pre-Columbian times. We compare the chronology of those cultural transitions with high-resolution regional palaeoclimate proxies, showing that, while some societies faced major reorganisation during periods of climate change, others were unaffected and even flourished. We propose that societies with intensive, specialised land-use systems were vulnerable to transient climate change. In contrast, land-use systems that relied primarily on polyculture agroforestry, resulting in the formation of enriched forests and fertile Amazonian Dark Earths in the long term, were more resilient to climate change

Nonlinear landscape and cultural response to sea-level rise

Dataset S1 (separate file). Relative sea-level database for Scilly comprising directly dated radiocarbon and optically stimulated luminescence samples with corresponding metainformation (lithostratigraphy, elevation, depositional environment and indicative meaning interpretations, paleotidal range change and sea-level calculations) following the ‘HOLSEA’ (‘Geographic Variability of Holocene Relative Sea Level’) protocol (Khan et al., 2019*). Dataset S2 (separate file). Table containing pollen results as relative abundance (genus level), modelled ages and age uncertainty for pollen samples, landcover index results (community cluster numbers and nMDS ordination axes 1 and 2), foraminifera results as species counts and transfer function results as paleomarsh elevations with uncertainty (1σ). Foraminifera samples with low test concentrations have indicative ranges (from mean high water neap tides to highest astronomical tides) in place of paleomarsh elevation estimations. Foraminifera abbreviations: H.wil – Haplophragmoides wilbertii ; J.mac – Jadammina macrescens ; M.fus – Miliammina fusca ; P.ipo – Polysaccammina ipohalina ; T.inf – Trochammina infalta ; T.och – Trochammina ochracea ; A.bat - Ammonia batavus ; A.mam – Asterigerinata mamilla ; B.var – Bolivina variablis; E.cri – Elphidium crispum ; E.wil – Elphidium Williamsoni ; F.spp. – Fissurina spp. ; Elphidium spp. ; H.ger – Haynesina germanica ; L.lob – Lobatula lobatula ; O.spp. – Oolha spp. ; Q.sem – Quinqueloculina seminula; R.spp. – Rosalina spp.. Dataset S3 (separate file). Database containing three worksheets for developing archaeological indices for Scilly. ‘SWBritain’ – Radiocarbon dates from Devon and Cornwall used to develop a summed probability distribution curve as an estimate of population demographic variation in Southwest Britain. ‘NWFrance’ - Radiocarbon dates from Brittany and Normandy used to develop a summed probability distribution curve as an estimate of population demography in Northwest France. ‘Scilly’ – Archaeological monuments from Scilly used to develop a probabilistic index of population variability.The article associated with these datasets is located in ORE at: http://hdl.handle.net/10871/123489Rising sea levels have been associated with human migration and behavioral shifts throughout prehistory, often with an emphasis on landscape submergence and consequent societal collapse. However, the assumption that future sea-level rise will drive similar adaptive responses is overly simplistic. Whilst the change from land to sea represents a dramatic and permanent shift for pre-existing human populations, the process of change is driven by a complex set of physical and cultural processes with long transitional phases of landscape and socio-economic change. Here we use reconstructions of prehistoric sea-level rise, paleogeographies, terrestrial landscape change and human population dynamics to show how the gradual inundation of an island archipelago resulted in decidedly non-linear landscape and cultural responses to rising sea-levels. Interpretation of past and future responses to sea-level change requires a better understanding of local physical and societal contexts to assess plausible human response patterns in the future.Historic EnglandWelsh GovernmentHigher Education Funding Council for Wale

Reassessing climate and pre-Columbian drivers of paleofire activity in the Bolivian Amazon

A 50,000-year-old sediment core record from Laguna Chaplin is reanalyzed to explore potential paleoecological methods to detect the extent of pre-Columbian disturbance in the Bolivian Amazon. High-resolution (sub-centennial) macrocharcoal data are analyzed using statistical algorithm software including Regime Shift Detection and CHAR Analysis to detect changes in past fire regimes. These data are compared with existing charcoal records from throughout the Bolivian lowlands to provide a regional scale context of past biomass burning. During the mid-Holocene, changes in precipitation are the dominant driver of fire activity and biomass burning at Laguna Chaplin and across the Bolivian lowlands. During the late Holocene, increased fire activity across ecosystems ranging from fire-adapted to fire-intolerant forests is attributed to the apex of pre-Columbian activity. These data suggest human-caused ignitions during the late Holocene are the driving factor of regional scale fire activity in the Bolivian lowlands. After ca. 650 cal yr BP, there is an increase in biomass burning and fire frequency synchronous with the expansion of Moraceae/Urticaceae pollen (>50%) at Laguna Chaplin. This occurs during the time-transgressive southward expansion of the rainforest boundary, during the apex of pre-Columbian activity in the region. The increase in biomass burning at Laguna Chaplin is reflected at other sites in the region with known human occupation histories. The presence of Zea mays ca. 970 to 170 cal yr BP indicates maize cultivation is practiced in the immediate vicinity surrounding Laguna Chaplin. The simultaneous increase in fire activity with the expansion of the less flammable humid rainforest vegetation suggests human fire management practices. These data are interpreted as the use of frequent, low severity, human-caused fires to clear the croplands from encroaching rainforest vegetation. Despite evidence of pre-Columbian fire management during the late Holocene, vegetation and fire data indicate the extent of human-landscape modification and fire management at Laguna Chaplin, is not enough to inhibit the climate-driven regional forest expansion of the savanna-rainforest ecotonal boundary to its most southern extent in the last 50,000 years. This study demonstrates the utility of applying a multi-proxy, high-resolution paleoecological method to disentangle climate and pre-Columbian disturbance in the Bolivian Amazon

Developing Transdisciplinary Approaches to Sustainability Challenges: The Need to Model Socio-Environmental Systems in the Longue Durée

Human beings are an active component of every terrestrial ecosystem on Earth. Although our local impact on the evolution of these ecosystems has been undeniable and extensively documented, it remains unclear precisely how our activities are altering them, in part because ecosystems are dynamic systems structured by complex, non-linear feedback processes and cascading effects. We argue that it is only by studying human–environment interactions over timescales that greatly exceed the lifespan of any individual human (i.e., the deep past or longue durée), we can hope to fully understand such processes and their implications. In this article, we identify some of the key challenges faced in integrating long-term datasets with those of other areas of sustainability science, and suggest some useful ways forward. Specifically, we (a) highlight the potential of the historical sciences for sustainability science, (b) stress the need to integrate theoretical frameworks wherein humans are seen as inherently entangled with the environment, and (c) propose formal computational modelling as the ideal platform to overcome the challenges of transdisciplinary work across large, and multiple, geographical and temporal scales. Our goal is to provide a manifesto for an integrated scientific approach to the study of socio-ecological systems over the long term

Fire as a fundamental ecological process: Research advances and frontiers

© 2020 The Authors. Journal of Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society Fire is a powerful ecological and evolutionary force that regulates organismal traits, population sizes, species interactions, community composition, carbon and nutrient cycling and ecosystem function. It also presents a rapidly growing societal challenge, due to both increasingly destructive wildfires and fire exclusion in fire-dependent ecosystems. As an ecological process, fire integrates complex feedbacks among biological, social and geophysical processes, requiring coordination across several fields and scales of study. Here, we describe the diversity of ways in which fire operates as a fundamental ecological and evolutionary process on Earth. We explore research priorities in six categories of fire ecology: (a) characteristics of fire regimes, (b) changing fire regimes, (c) fire effects on above-ground ecology, (d) fire effects on below-ground ecology, (e) fire behaviour and (f) fire ecology modelling. We identify three emergent themes: the need to study fire across temporal scales, to assess the mechanisms underlying a variety of ecological feedbacks involving fire and to improve representation of fire in a range of modelling contexts. Synthesis: As fire regimes and our relationships with fire continue to change, prioritizing these research areas will facilitate understanding of the ecological causes and consequences of future fires and rethinking fire management alternatives

Warming, drought, and disturbances lead to shifts in functional composition: a millennial‐scale analysis for Amazonian and Andean sites

Tropical forests are changing in composition and productivity, probably in response to changes in climate and disturbances. The responses to these multiple environmental drivers, and the mechanisms underlying the changes, remain largely unknown. Here, we use a functional trait approach on timescales of 10,000 years to assess how climate and disturbances influence the community-mean adult height, leaf area, seed mass, and wood density for eight lowland and highland forest landscapes. To do so, we combine data of eight fossil pollen records with functional traits and proxies for climate (temperature, precipitation, and El Niño frequency) and disturbances (fire and general disturbances). We found that temperature and disturbances were the most important drivers of changes in functional composition. Increased water availability (high precipitation and low El Niño frequency) generally led to more acquisitive trait composition (large leaves and soft wood). In lowland forests, warmer climates decreased community-mean height probably because of increased water stress, whereas in highland forests warmer climates increased height probably because of upslope migration of taller species. Disturbance increased the abundance of acquisitive, disturbance-adapted taxa with small seeds for quick colonization of disturbed sites, large leaves for light capture, and soft wood to attain fast height growth. Fire had weak effects on lowland forests but led to more stress-adapted taxa that are tall with fast life cycles and small seeds that can quickly colonize burned sites. Site-specific analyses were largely in line with cross-site analyses, except for varying site-level effects of El Niño frequency and fire activity, possibly because regional patterns in El Niño are not a good predictor of local changes, and charcoal abundances do not reflect fire intensity or severity. With future global changes, tropical Amazonian and Andean forests may transition toward shorter, drought- and disturbance-adapted forests in the lowlands but taller forests in the highlands

Developing Transdisciplinary Approaches to Sustainability Challenges: The Need to Model Socio-Environmental Systems in the Longue Durée

Human beings are an active component of every terrestrial ecosystem on Earth. Although our local impact on the evolution of these ecosystems has been undeniable and extensively documented, it remains unclear precisely how our activities are altering them, in part because ecosystems are dynamic systems structured by complex, non-linear feedback processes and cascading effects. We argue that it is only by studying human–environment interactions over timescales that greatly exceed the lifespan of any individual human (i.e., the deep past or longue durée), we can hope to fully understand such processes and their implications. In this article, we identify some of the key challenges faced in integrating long-term datasets with those of other areas of sustainability science, and suggest some useful ways forward. Specifically, we (a) highlight the potential of the historical sciences for sustainability science, (b) stress the need to integrate theoretical frameworks wherein humans are seen as inherently entangled with the environment, and (c) propose formal computational modelling as the ideal platform to overcome the challenges of transdisciplinary work across large, and multiple, geographical and temporal scales. Our goal is to provide a manifesto for an integrated scientific approach to the study of socio-ecological systems over the long term