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Paul Bishop's contribution to the earth sciences is profound. His work on large spatial and temporal scale landscape evolution is well known, but he also (and coevally) directed his attention to the complexities of human–environmental interactions, with all their site-based and short-term cultural idiosyncrasies. His focus on mainland SE Asia, and Thailand in particular, reflects a long-standing fascination in and affection for the region and its people. His natural inquisitiveness stimulated work in historic climate change, the emergence of complex states, Quaternary landscape evolution and the geochronology of anthropogenically modified sediments, among many other areas. His work on human–environment interactions drew on and strengthened links with many people and institutions, and between Geographical and Earth Sciences and the Scottish Universities Research Centre at the University of Glasgow, in particular. Just as important as his contribution to the earth sciences was his contribution to the development of his students and other mentees, and his role in shaping our careers was enormous. [ABSTRACT FROM AUTHOR]

Previous syntheses of palaeoclimate and archaeological data from the Kashmir Valley have proposed that climate changes drove prehistoric settlement of the valley, based on the adaptation of West Asian winter crops to mid-Holocene warm-humid conditions ca. 5000 BP. It has been argued that these conditions enabled population growth that became unsustainable following the onset of a cold-arid phase ca. 3000 BP, with these cycles of growth and collapse again repeating ca. 2000 and 1000 BP. Here we present multi-proxy palynomorph, charcoal and sediment data indicating that from ca. 4500-1500 BP the environment of the valley was characterised by drier conditions, comparable to other regional records indicating weakening Westerly precipitation over Central Asia. Considering recent archaeobotanical data indicating the presence of both West Asian winter crops and East Asian summer millets in the valley as early as 4500 BP, we argue that rather than Malthusian cycles of growth and collapse in Kashmir, early populations likely drew on a broad range of available domesticates and varied ecotopes across the valley to allow a Boserupian response to changing Holocene climate conditions. These adaptations were likely more oriented towards flexible systems of agro-pastoralism practiced throughout the Inner Asian mountains, rather than towards developing large urban settlements as was the case in the river basins and plains south of Kashmir. [ABSTRACT FROM AUTHOR]

Historical societies reshaped their environment in various ways; by clearing forest, cultivating crops, mining, and modifying waterways. Evidence of these activities persists in palaeoenvironmental archives, which represent comprehensive histories of human activity in a landscape. Analysis of settlement networks across landscapes is another common approach to investigating how past societies operated, but these analyses rarely incorporate palaeoenvironmental data. Here, we combine these two data sources to examine past socio‐political relationships in a society that experienced disruption and transformation. Applying network analysis, and using settlement histories built from palaeoenvironmental proxies for occupation and land use, this paper reconstructs population dynamics at several key nodes (cities) within the Khmer kingdom of Southeast Asia, before and after the climate stress and political upheaval of the 14th–15th centuries ce. Our results reveal how the Khmer city network transformed across space and the nature of the relationships that existed within the network prior to its disruption. [ABSTRACT FROM AUTHOR]

The River Murray Estuary, South Australia exhibits a morphology typical of a wave-dominated estuary and comprises two large, shallow central basin lakes – Lakes Alexandrina and Albert. Contested interpretations of the estuary's limnological history and uncertainty surrounding the sustainability of current basin water usage practice warrant a robust investigation into how the system has evolved. Here we combine lithostratigraphic, geochemical and sedimentological evidence from a transect of sediment cores to reconstruct the sediment infill history of the system. We uncover multiple stages of sediment infill over the history of the system, associated with (1) the low gradient morphology of the estuary and lower river channel, (2) the mid- to late-Holocene sea-level regression and (3) anthropogenic modifications to the fluvio-estuarine system. We show that while estuarine conditions in the system were fully established during the mid-Holocene highstand (~6.4 kyr BP), central basin facies sedimentation was focussed further inland before prograding with the lowering of base level and shifting of tidal influence as sea-level fell. Central basin facies sedimentation within northern Lake Albert occurred from 5.4 to 4.0 cal kyr BP at ~0.25 cm yr-1. The uppermost accumulation of this unit was eroded by continued reduction in base level until sea-level regression concluded at 3.5 cal kyr BP. Barrage and weir installation (1940 CE) re-initiated and expanded central basin facies sedimentation in the estuary (~0.32 cm yr-1). Recently deposited sediments exhibit geochemical markers of increased trophy and more frequent acid sulfate soil acidification, exposing human impacts on the estuary. [ABSTRACT FROM AUTHOR]

Alternative models exist for the movement of large urban populations following the 15th-century CE abandonment of Angkor, Cambodia. One model emphasizes an urban diaspora following the implosion of state control in the capital related, in part, to hydroclimatic variability. An alternative model suggests a more complex picture and a gradual rather than catastrophic demographic movement. No decisive empirical data exist to distinguish between these two competing models. Here we show that the intensity of land use within the economic and administrative core of the city began to decline more than one century before the Ayutthayan invasion that conventionally marks the end of the Angkor Period. Using paleobotanical and stratigraphic data derived from radiometrically dated sediment cores extracted from the 12th-century walled city of Angkor Thom, we show that indicia for burning, forest disturbance, and soil erosion all decline as early as the first decades of the 14th century CE, and that the moat of Angkor Thom was no longer being maintained by the end of the 14th century. These data indicate a protracted decline in occupation within the economic and administrative core of the city, rather than an abrupt demographic collapse, suggesting the focus of power began to shift to urban centers outside of the capital during the 14th century. [ABSTRACT FROM AUTHOR]

Throughout the Angkor period (9th to 15th centuries CE), the Khmer kingdom maintained a series of interconnected cities and smaller settlements across its territory on mainland Southeast Asia. One such city was Koh Ker, which for a brief period in the 10th century CE even served as a royal capital. The complexity of the political landscape meant the Khmer kings and the elite were particularly mobile through the Angkor period, and rupture in royal houses was common. However, while the historical record chronicles the 10th century migration of the royal seat from Koh Ker back to Angkor, the fate of Koh Ker’s domestic population has remained unknown. In this article, we reconstruct the settlement history of Koh Ker, using palaeoecological and geoarchaeological techniques, and show that human activity and land use persisted in the city for several centuries beyond the city’s abandonment by the royal court. These results highlight the utility of multi-proxy environmental reconstructions of Khmer urban settlements for re-evaluating prevailing assumptions regarding the use and occupation of Angkor-period cities. [ABSTRACT FROM AUTHOR]

Persistent drought over eastern Australia at the turn of the last millennium reduced stream flow in Australia's largest and most economically important drainage basin. Low water levels in the basin's terminal lakes triggered widespread pyrite oxidation, which altered surface water chemistry and released metals into the environment. The frequency of these events, and the links between drought and acid sulfate soil activation, are not known because the historical and instrumental records are short. Here, we present a Holocene-aged record of trace metal enrichment from Lake Albert—part of the terminal Lower Lakes system of the Murray-Darling Basin, Australia—that demonstrates the potential of trace elements mobilised during acidification events for palaeodrought reconstructions. Symptomatic metals were measured from a core of clayey sediment to form a multi-element assemblage that reveals acidification events in the geological past. Correlation with regional climate proxies suggests that climate forcing is significant in driving metal flux to estuarine sinks in acid sulfate soil rich landscapes, although the intensity of a drought is not the only variable responsible for acidification intensity. The constructed record indicates that regional climate moved from a generally humid climate phase with intermittent droughts, to a more arid climate at ~ 5.2 ka which prevailed until ~ 1.7 ka. Following conditions were relatively wet with low climatic variability through till European Settlement. Enrichment is observed coincident with both the 1982–83 drought and Millennium Drought, the latter of which reaching an intensity unsurpassed in the last ~ 4.8 ka, likely a product of anthropogenic changes to the Lower Murray-Darling Basin system. [ABSTRACT FROM AUTHOR]

The Botany Wetlands are the contemporary remnant of a formerly extensive coastal freshwater wetland in the inner-urban suburbs of Sydney (Australia). This site supports a range of ecosystem services, including human physical and mental health benefits, filtration of stormwater runoff from a highly urban and industrial catchment, and accommodation space for floodwater. The wetlands also provide habitat to migratory water birds and act as a connective habitat corridor and refuge for native flora and fauna including endangered ecological communities recognised in state and national legislation. Current management strategies and 'on the ground' practices are informed by a hierarchy of laws and management plans that act to create and reinforce a specific narrative in the material landscape. Here we consider the ecological history of the wetlands, derived from paleoecological data, in the context of this complex network of governance entanglements. We argue that the system bears little resemblance to its long-term character and has been made and continually re-made by a portmanteau of inflexible regulatory structures. We suggest that maintaining ecosystem services in such a complex, hybridized sociolegal-biophysical system requires a critical view of both the power relations and physical processes that shape it. [ABSTRACT FROM AUTHOR]

Yeak Loam is a volcanic crater lake in Cambodia’s northeastern uplands, and represents an important economic and cultural resource for local ethnic minority groups. The lake and the surrounding crater rim are currently protected as part of a community based natural resource management scheme. Despite this, development pressure remains high, and visible deterioration of the lake’s water quality is of great concern for the local community, visiting tourists, and the Cambodian Ministry of Environment. In this paper we blend scientific analyses with vernacular, place-based knowledge – coherent with the critical physical geography concept – to provide an integrated understanding of water quality change over more than 50 years. We find that changes in water quality have occurred episodically and irregularly over that period. Further, we find that these events are triggered by natural biogeochemical cycles within the lake, and in this instance are unlikely to be related to the type of land use within the protected area. [ABSTRACT FROM AUTHOR]

Reconstructing the environmental history of protected areas permits an empirically-based assessment of the conservation values ascribed to these sites. Ideally, this long-term view can contribute to evidence-based management policy that is both ecologically ‘realistic’ and pragmatically feasible. Lachlan Nature Reserve, a protected wetland in Centennial Park, Sydney, is claimed to be the final remnant of early and pre-European swamplands that were once extensive in the area, and the site is thus considered to have indigenous cultural and natural conservation significance. This study uses palynological techniques to reconstruct vegetation communities at the Reserve from the late Holocene to the present in order to assess whether these values adequately reflect the history, character and development of the site. The findings indicate that the modern site flora is a modified Melaleuca quinquenervia low forest assemblage formed in response to aggregated anthropogenic disturbance since colonial settlement. This assemblage replaces an Epacris-dominated heath-swampland community that was extirpated in the mid-20th century. These results emphasize the value of long-term studies in contributing to a realistic management policy that explicitly reflects the normative basis of conservation, and values the influence of past land-uses on contemporary protected ecosystems. [ABSTRACT FROM PUBLISHER]

The important role mangrove forests play in sequestering organic carbon is well known, yet rates of organic carbon accumulation in macro‐tidal mangrove ecosystems are poorly resolved. Here we use 210Pb dating to present a 125‐yr record of carbon, nutrient and trace metal accumulation in sediments from an Amazon macro‐tidal mangrove forest. We find that the rate of organic carbon accumulation ranged from 23.7 to 74.7 g m−2 yr−1 (average 38 ± 13.5 g m−2 yr−1), significantly lower than global averages for mangrove forests. These low rates may be associated with sediment grain‐size and sediment–water interface processes that drive organic matter oxidation and reduce carbon stocks in these highly dynamic macro‐tidal forests. Total nitrogen accumulation ranged from 1.4 to 5.1 g m−2 yr−1 (average 2.7 ± 0.9 g m−2 yr−1) and phosphorus from 1.5 to 8.4 g m−2 yr−1(average 4.3 ± 1.9 g m−2 yr−1). Trace metal accumulation rates (As, Pb, Cr, Cu, Mn, Ni, Zn, Hg, Bo, V, Co, Mo, S, and Ba) were also lower than other tropical mangrove forests globally, but trace metal in more recent sediments for Mn, As, Cu, and Hg were elevated, likely reflecting human footprint in the region since early the 20th century. The ability to accurately quantify carbon accumulation rates in mangrove ecosystems is critical for climate change mitigation strategies and the implementation of carbon offset schemes globally. [ABSTRACT FROM AUTHOR]

The Khmer kingdom, whose capital was at Angkor from the 9th to the 14th-15th century, was founded in 802 by king Jayavarman II in a city called Mahandraparvata, on Phnom Kulen. Virtually nothing more is known of Mahandraparvata from the epigraphic sources, but systematic archaeological survey and excavation have identified an array of cultural features that point to a more extensive and enduring settlement than the historical record indicates. Recent remote sensing data have revolutionized our view, revealing the remains of a city with a complex and spatially extensive network of urban infrastructure. Here, we present a record of vegetation change and soil erosion from within that urban network, dating from the 8th century CE. Our findings indicate approximately 400 years of intensive land use, punctuated by discrete periods of intense erosion beginning in the mid 9th century and ending in the late 11th century. A marked change in water management practices is apparent from the 12th century CE, with implications for water supply to Angkor itself. This is the first indication that settlement on Mahendraparvata was not only extensive, but also intensive and enduring, with a marked environmental impact. [ABSTRACT FROM AUTHOR]

Paleoclimate research in the Maya region of Mesoamerica provides compelling evidence of drought during key periods of cultural transition in Maya society. These include the transition from the Preclassic to the Classic, and from Classic to the Postclassic. Previous research emphasized a causal relationship between drought and cultural change, or so-called "collapse" in the Maya region. Recent advances in the range and precision of climate-sensitive proxies and the development of new archives have enabled quantitative reconstructions of past hydroclimate, as well as providing evidence of high impact, short-duration events, such as tropical cyclones. Simultaneously, archaeological research has unearthed widespread evidence of technologies used by the Maya to exert control over water resources in urban, rural, and agricultural settings. Evidence suggests that many of these water features were in use for multiple generations, possibly centuries, and many were constructed during the Terminal Preclassic and Terminal Classic periods. We suggest that, given the availability of new archaeological and paleoclimate records, these data can be combined to identify the full complexity of Maya adaptation to hydroclimate variability to emphasize adaptation and resilience to both water scarcity and over-abundance (e.g., flooding). Such syntheses, which can offer lessons for present-day efforts to grapple with regional climate change, will benefit from additional studies in data-poor zones of the Maya region, as well as public archiving of paleoclimate and archaeological data. [ABSTRACT FROM AUTHOR]

The consequences of protected areas for proximal human communities are diverse. Protected areas can alleviate poverty by providing a range of economic opportunities for people that live and work within them. Equally, however, they may also disempower and disposes local communities. For communities adapting to systemic environmental change, proximity to protected areas can act to limit potential adaptive pathways. Here, we employ social science methods to explore the impact of an internationally significant protected area on adjacent communities in the Tonle Sap Lake basin, Cambodia. Semi-structured interviews, informed by a scenario framework, reveal an awareness of declining fish yields and a perceived lack of economic alternatives. Vulnerability to hydroclimatic extremes, particularly storms, flood, drought and – increasingly – fire, are exacerbated as a result of proximity to the protected area. We conclude that the impact of protected areas on local communities is heterogenous, and that the development of adaptive and effective management policies requires sensitivity to local conditions and impacts. • The proximity of resource-dependent communities to protected areas may restrict their adaptive capacity. • Fishing communities adjacent to Ramsar wetlands are vulnerable to environmental change. • Options for alternative livelihoods are perceived to be limited. • Fire is an ascendant natural hazard in seasonal tropical wetlands. [ABSTRACT FROM AUTHOR]

The wetlands of the lower Mekong River Basin are ecologically and socioeconomically significant, but they are threatened by predicted climatic change. The likely response of wetland ecosystems to altered flooding regimes and surface-water chemistry is unknown in detail and difficult to model. One way of exploring the impact of climate change on wetland ecosystems is to utilize proxy environmental data that reveal patterns of change over geological time. In recent years, the coverage and resolution of proxy climatic data have improved markedly in the region. Recent evidence of the South China Sea transgression into southern and central Cambodia and paleobotanical evidence from the Tonle Sap ("Great Lake") and elsewhere allow us to explore how periods of higher-than-present sea level and increased monsoon rainfall in the past have impacted the wetland ecology of the lower Mekong River Basin. [ABSTRACT FROM AUTHOR]

It has been claimed that Tonle Sap Lake is rapidly filling with sediment as a result of increasing sediment yields from the catchment. Infilling of the lake basin would have serious implications for the magnitude of flooding in central Cambodia and the Mekong Delta region and threaten the lake's unique ecosystem. In this article, we synthesize the results of radiocarbon dating of sediment cores and hydrodynamic modeling results to provide an empirically based assessment of this issue. We find that current sedimentation rates within the lake basin proper are low and have been for several millennia. However, sedimentation at the lake margin and in its floodplain is relatively high, which presents a range of issues for riparian communities. [ABSTRACT FROM AUTHOR]

Web technologies have given publishers and researchers alike opportunities to interact in new ways. These have had an impact on business models, the value of formal and informal communication, and the role of publishers in the networked community. This article looks at some recent examples which are likely to set precedents for the future of publishing technologies. In particular, it focuses on the evolution of Web searching, the growing importance of online communities, the potential of Web tools for self-publishing, and the way in which publishers can control their content even post-publication. It also suggests that the recent rash of e-book readers is unlikely to be of importance to scholarly publishing. [ABSTRACT FROM AUTHOR]

Abstract: Angkorian temples are characterised by one or more encircling moats that are excavated into the alluvial substrate. As a key part of the overall design of the temple, the moats are important symbolically and are presumed to be contemporaneous with the associated temple. They also represent important depositional basins for sediment and other materials and can therefore yield vertical profiles of sediment that has accumulated since the moat was originally excavated. Unconformities in these moat profiles can be dated absolutely using small-sample, high-precision AMS radiocarbon techniques. These unconformities are likely to represent periodic re-excavation or maintenance of the moat and therefore indicate the presence of large, presumably centrally organised workforces. In some instances, presumed anthropogenic unconformities occur centuries after Angkor was supposedly abandoned. In this way, radiocarbon dates themselves are being used as a proxy indicator of cultural activity and are being used to challenge the historiography of Angkor’s famous demise. [Copyright &y& Elsevier]

Abstract: The Tonle Sap, the ‘Great Lake’ of central Cambodia, is the central component of wetland ecosystems in the lower Mekong River basin, and is of enormous conservation value. The lake''s unusual hydraulic relationship with the Mekong River, and its consequent sensitivity to monsoon variability, makes the Tonle Sap sensitive to climate change. Exploring the dynamics and development of this system under different climate regimes of the past offers a perspective on possible future impacts, which is critical for sound management. Biostratigraphic and sedimentological data derived from cores of lake sediment indicate that during the period >7000 to ca. 5500 14C years Before Present the lake was less variable than present in terms of depth during the annual cycle of flood, and may have been strongly influenced by saline tidal waters associated with higher-than-present seas levels. As regional environments became drier and more seasonal in the late Holocene, more sediment was re-suspended during the increasingly marked dry season lake level minimum, lowering the effective sediment accumulation rate. Contrary to current interpretations of the history of the lake and associated wetland ecosystems, the data presented here imply that regional hydraulic connections between the lake and the Mekong River existed from at least the early Holocene. [Copyright &y& Elsevier]

Abstract: Palaeo-environmental data from accumulated lake sediments at Phayao, northwest Thailand, provide a record of vegetation and environmental change from approximately 20,000 years Before Present. This is an important region archaeologically, with claims in the 1970s for an ‘early’ transition to domestication having arisen from a number of cave sites. Multiple indices are used to determine if people had an observable impact on the natural environment, and to determine the timing and magnitude of impacts associated with the development of agricultural land use in the region. An initial increase in sedimentation rate is apparent from ca. mid-2nd C AD. Changes in phytoplankton concentrations are apparent from the late 3rd C AD, and evidence for initial forest disturbance is apparent from the 5th or 6th C AD, with impacts becoming more severe over time to reach a pre-modern maximum in the 11th to the 13th C AD. Changes in agricultural practices are apparent during the 14th C AD, with an increased emphasis on rice agriculture and incipient management of the regenerating forests. Based on these data we suggest that agricultural intensification in the early part of the 1st millennium AD destabilised catchment slopes, through clearance of dryland vegetation and swidden agriculture. There is no direct evidence for the impacts of earlier peoples on the vegetation of the area, which we take to indicate that agricultural intensification was later here than in the lowlands to the east and south. [Copyright &y& Elsevier]

Investigates the pollen content of lake sediments taken from Ban Chiang, Thailand. Data which can be gleaned from palynology; Description of the fieldwork involved; Patterns of vegetation uncovered; Formulation of the hypothesis that there were humans in the area 6500 years ago.

Exploring severe social, political, or economic change in past societies can reveal adaptive pathways and strategies that may be of value to contemporary society as we prepare to adapt to this century of disruption. Episodes of large-scale transformation in past societies are often framed as 'collapse' – as terminal events instigated by one or more stressors. The focus on cataclysmic episodes, often related to climatic forcing, has meant that the nuance of adaptation is not well documented in historical and archaeological records, in part due to the historical lacuna that may follow periods of social disruption. Here we present a multi-proxy record of landscape and land use change from Angkor, the administrative and ceremonial core of the Angkorian kingdom in ancient Cambodia, through a period of severe climate stress and political transition in the 14th-15th centuries to the present-day. Analysis of proxy data, including geochemistry, palynology, sedimentology, and fire history, reveal a prolonged period of land use attenuation beginning in the early to mid-14th century, interrupted by a brief increase in burning and cultivation that may represent a short period of reoccupation in the mid-16th century. Agricultural activity continued to decline, despite continuing ritual activity within the site of Angkor Thom and ongoing occupation at temple sites in the Greater Angkor region, until the 17th century when metrics for secondary forest growth and landscape recovery reached consistently high levels. These results provide further evidence exposing the varied trajectories of occupation across key Cambodian urban centres, and contribute to the developing narrative of Angkor as a city that underwent transformation, rather than collapse, between the Angkorian (c. 800- c. 1450 C.E.) and Early Modern (c. 1450 - c. 1850 C.E.) periods. • Records of landscape change contextualise cultural evidence of societal transition. • Narratives that extend beyond disruption can reveal examples of social resilience. • Angkor's evolution from the Angkorian to Early Modern Periods was spatially complex. • Angkor Thom's population fell from the 14th C. but the city endured as a sacred district. [ABSTRACT FROM AUTHOR]

Extreme prolonged drought over south-eastern Australia a decade ago (the Millennium Drought, 1996–2010) triggered extensive acid sulfate soil oxidation and associated acidification. Whilst the significant release of metal-enriched drainage has been documented during this event, the fate of these elements in receiving systems is still largely unknown. Here we investigate the spatial distribution, chemical partitioning, and potential bioavailability of S, Fe, Mn, Al, trace metals (V, Cr, Co, Ni, Cu, Pb) and rare earth elements in the surficial sediments of Lake Albert, South Australia; a system that received prolonged (2007–2011) acidic drainage during the Millennium Drought. The highest concentrations of all metals (Enrichment Factors ranging from 1.06–1.97) were observed in the sediments closest to shorelines where sulfidic material were oxidised, generating metal-enriched acidic drainage. Localised enrichment indicates metals have not been completely redistributed across the system following their initial deposition by physical (wind-driven resuspension) or chemical (diagenetic and redox changes) processes. Based on selective extraction data, these metals are likely partitioned as discrete sulfides (Pb) or are with organic material (V, Cr, Cu, Pb, REEs), Fe monosulfides (V, Co, Ni), or pyrite (Co, Ni, Pb). Lake-wide enrichment of trace metals Cr (mean concentration 57 ppm), Ni (39 ppm), Cu (36 ppm), and Pb (24 ppm) relative to other Lower Murray River sites is also evident, suggesting that metal contamination associated with acidic drainage is not restricted to near-source sites. Importantly, the mobilisation, transport, and accumulation of metals is controlled by sediment transport pathways and system hydrology and will thus function differently under varying states of geomorphology, climate, and anthropogenic modification. Our study shows that extreme drought is recorded as a lasting geochemical signature in estuarine sediments, demonstrating that metal and rare earth element geochemistry provides insights into the distribution and behaviour of contaminants mobilised into dynamic, anthropogenically altered estuaries. Unlabelled Image • Extreme drought triggered extensive acid sulfate soil oxidation and acidification. • Acidic drainage mobilised major, trace and rare earth metals into the estuary. • This caused localised and lake-wide enrichment of metals in recent sediments. • Sediment transport processes shaped metal transport and deposition. • Estuary geomorphology contributed to the intensity of metal release. [ABSTRACT FROM AUTHOR]

Tropical forests are the most biodiverse terrestrial ecosystems on earth, yet are particularly susceptible to future climatic and human-induced change. Identifying tipping points at which tropical ecosystems will reorganise is therefore an important research goal. Limited research within the seasonally dry tropical forests of south-east Asia means that much uncertainty exists around the resilience of these systems to future global change. This is a critical research gap because these forests should – given their physiognomic attributes, current bioclimatic envelope and the range of stressors – be very sensitive to a stable-state shift to savanna. Here we adopt a palaeoecological approach to examine the interaction between key drivers of change (decreased precipitation and heightened fire activity) and forest response over ∼4700 years though interrogation of sediment-based proxies from volcanic crater lakes within north-east Cambodia – in the core range of southeast Asia's tropical dry forests. Our results suggest that rapidly regenerating, secondary forest taxa are important for maintaining a forested state when the landscape is subject to moderate fire and climatic disturbance. However, when these stressors are amplified, recovery and resistance traits associated with key deciduous dipterocarp forest taxa appear critical for forest stability. Notably, shifts from more closed, seasonal evergreen forest formations to more open secondary/deciduous dipterocarp formations appear reversible when the stressors are removed, suggesting that these transitions are not analogous with the difficult-to-reverse, forest-to-savanna stable state shifts that occur elsewhere in Neotropical and Afrotropical settings. Our results indicate that the resilience of south-east Asian forests to climatic forcing appears contingent on the maintenance of secondary forest, deciduous forest, and seasonal evergreen dry forest mosaics across the ecoregion. This has implications for the conservation and wise-use of mainland south-east Asia's lowland dry forests. • We explore the response of Asian seasonal forests to fire and drought over 4.7ka. • Landscape mosaics support forest recovery and resistance in response to disturbance. • Maintaining traditional swidden techniques appears important for forest conservation. • SE Asian forest resilience to fire and drought contradicts global biome theory. • Resilience is contingent on evolutionary history and landscape heterogeneity. [ABSTRACT FROM AUTHOR]

A growing body of archaeological research on agro-pastoralist populations of the Inner Asian mountains indicates that these groups adapted various systems of mobile herding and cultivation to ecotopes across the region from as early as 5000 BP. It has been argued that these adaptations allowed the development of flexible social-ecological systems well suited to the long-term management of these mountain landscapes. At present, less attention has been paid to examining the long-term ecological legacy of these adaptations within the sedimentary or palaeoenvironmental record. Here we present sediment, palynomorph and charcoal data that we interpret as indicating agro-pastoralist environmental perturbations, taken from three cores at middle and high altitudes in the Kashmir Valley at the southern end of the Inner Asian mountains. Our data indicate spatially and temporally discontinuous patterns of agro-pastoralist land use beginning close to 4000 BP. Periods of intensification of upland herding are often coincident with phases of regional social or environmental change, in particular we find the strongest signals for agro-pastoralism in the environmental record contemporary with regionally arid conditions. These patterns support previous arguments that specialised agro-pastoralist ecologies across the region are well placed to respond to past and future climate deteriorations. Our data indicating long-term co-evolution of humans and landscape in the study area also have implications for the ongoing management of environments generally perceived as "pristine" or "wilderness". [ABSTRACT FROM AUTHOR]

The dominant paradigm is that large tracts of Southeast Asia's lowland rainforests were replaced with a "savanna corridor" during the cooler, more seasonal climates of the Last Glacial Maximum (LGM) (23,000 to 19,000 y ago). This interpretation has implications for understanding the resilience of Asia's tropical forests to projected climate change, implying a vulnerability to "savannization". A savanna corridor is also an important foundation for archaeological interpretations of how humans moved through and settled insular Southeast Asia and Australia. Yet an up-to-date, multiproxy, and empirical examination of the palaeoecological evidence for this corridor is lacking. We conducted qualitative and statistical analyses of 59 palaeoecological records across Southeast Asia to test the evidence for LGM savannization and clarify the relationships between methods, biogeography, and ecological change in the region from the start of Late Glacial Period (119,000 y ago) to the present. The pollen records typically show montane forest persistence during the LGM, while δ13C biomarker proxies indicate the expansion of C4-rich grasslands. We reconcile this discrepancy by hypothesizing the expansion of montane forest in the uplands and replacement of rainforest with seasonally dry tropical forest in the lowlands. We also find that smooth forest transitions between 34,000 and 2,000 y ago point to the capacity of Southeast Asia's ecosystems both to resist and recover from climate stressors, suggesting resilience to savannization. Finally, the timing of ecological change observed in our combined datasets indicates an 'early' onset of the LGM in Southeast Asia from ~30,000 y ago. [ABSTRACT FROM AUTHOR]

Mangrove ecosystems are dynamic and biodiverse environments with the capacity to sequester more organic carbon per unit area, per time, than terrestrial forests, yet are among one of the most heavily degraded ecosystems on Earth. Here, we quantify trace metal, nutrient and carbon accumulation rates in a tropical mangrove environment in northeast Brazil, a region that has been rapidly developed over the past seven decades. Carbon accumulation rate results show modest or no increase since the 1950's, when major development occurred in the region. Organic carbon isotope (δ13C) and C:N molar ratios indicate that the OM is primarily derived from autochthonous C 3 plant sources. However, the most recent sediments revealed changes from terrestrial to alga-derived source of OM, which is consistent with the increase of total nitrogen, δ15N and total phosphorous content in the last seven decades, suggesting anthropogenic impact. Furthermore, the Hg enrichment factor (EF) in mangrove sediments is shown to have increased 13-fold since the 1960's, highlighting the ability of tropical mangrove systems in trap filtering pollutants from proximal urban development. • Mangrove forests provide a range of environmental services, including carbon burial. • Increasing nutrient burial in a tropical estuary is driven by rapid urban growth. • The most recent sediments indicate changes in the source of organic matter. • Mercury enrichment has increased up to 13-fold since the 1960's. • Tropical mangroves are important sinks for pollutants in areas of rapid development. [ABSTRACT FROM AUTHOR]