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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]

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]

The Tonle Sap is an invaluable resource for the people of Cambodia, and is a globally significant ecological site. Much of the literature published on the environmental health and management of the lake suggests that its sustainability is threatened by accelerated rates of infilling related to unfettered land-use in the catchment. However, the evidence for supposedly increased sedimentation rates is confused and contradictory, and there have been very few studies that have attempted to actually measure the rate at which sediment is accumulating on the bed of the lake. This research measures long-term sedimentation rates in the Tonle Sap in an attempt to provide an empirically derived ‘baseline’ against which more recent and allegedly accelerated sedimentation rates can be compared. Radiometric dating techniques (14C, 210Pb, 137Cs) reveal that sediment has been accumulating in the lake at an average long-term rate of less than 1 mm per year. There is a clear and consistent decline in the rate of sediment accumulation in the lake basin over time, with the highest rates recorded in the middle to early Holocene epoch. It is recommended that research be directed toward measuring changes in the morphology of the lake margin over time, rather than focus on changes in the bathymetry of the lake basins themselves, which are here shown to be effectively stable in terms of sediment accumulation. [ABSTRACT FROM AUTHOR]

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]

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]

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., Competing Interests: The authors have declared that no competing interests exist.

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.

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.