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The present study provides the first quantitative assessment of the deteriorative impact of forest clearance on susceptible sandstone masonries. At Ta Keo, a 1000 yr-old temple cleared of the Angkor forest in the early 20th century, GIS-based analysis of historic imagery indicates an average ten-fold increase in stone loss rates (0.2 instead of 0.02% per year). This accelerated decay is assigned to the climatic stress provoked by the exposure of fragile ornamented sandstones to the harsh impact of tropical sunshine and monsoon rains. Comparative climate monitoring with the Beng Mealea temple, still located in a forested environment, suggests a three-fold post-clearance increase in daily temperature and humidity ranges, which is conducive to enhanced swelling-shrinking movements responsible for accelerated sandstone contour scaling. Comparative visual assessment based on a customised 7-point scale of mechanical weathering confirms the protective role of canopy, with 79% of decorative motifs still almost free of mechanical weathering in the forest (against 7% at the cleared site). Disruption of archaeological structures by roots of individual trees can be locally observed at Angkor, but this does not negate the dominant overall buffering function of the forest cover. At Angkor and other cultural heritage sites, this bioprotective 'umbrella effect' should be considered as a valuable ecosystem service to be taken into account when defining and implementing strategies of sustainable management. [ABSTRACT FROM AUTHOR]

Structure from Motion (SfM) photogrammetry, on-site hardness and water absorption tests, and petrographical and porosimetric analyses on targeted samples were carried out on representative areas within six different locations of Maltese fortifications affected by salt weathering. The objective was to quantify the limestone loss over the last half-millennium and to attempt to identify the controlling factors of durability. The results highlight the existence of a two-rate weathering regime within the Miocene Globigerina Limestone which is the main building stone of the Maltese Islands. With a median stone recession of 1.4 mm/century, the subtype locally called Franka has resisted atmospheric aggression on average 36 times better than the Soll subtype (median stone recession of 50 mm/century). The Oligo-Miocene Coralline Limestone has also resisted well, with a stone recession of on average 1.3 mm/century. Two main controls of the varying durability of these limestones have been identified. First, the water uptake capacity of the least durable, already weathered limestone (Soll) is two to three times higher than that of the weathered but more resistant Franka and Coralline Limestone (6.3 g.m−2.s−1 against 2.5 g.m−2.s−1). Second, there is a marked difference in cohesiveness between these limestones. Whereas the weathered, susceptible Soll facies is poorly-cemented or microcracked, the exposed durable Franka displays an abundant micritic and microsparitic matrix. The statistical relationship between durability and surface hardness is not straightforward, and other controls such as the clay content of limestones should be explored. Investigating a larger number of sites would allow the refining of the limestone durability scale inferred from the present study. • SfM photogrammetry and on-site tests were carried out on Maltese fortifications. • A two-rate weathering regime was highlighted within the building limestones. • Cohesiveness and water uptake capacity were identified as controlling factors. • There is no straightforward correlation between durability and surface hardness. [ABSTRACT FROM AUTHOR]

Over the last twenty years, significant technical advances turned photogrammetry into a relevant tool for the integrated analysis of biogeomorphic cross-scale interactions within vegetated fluvial corridors, which will largely contribute to the development and improvement of self-sustainable river restoration efforts. Here, we propose a cost-effective, easily reproducible approach based on stereophotogrammetry and Structure from Motion (SfM) technique to study feedbacks between fluvial geomorphology and riparian vegetation at different nested spatiotemporal scales. We combined different photogrammetric methods and thus were able to investigate biogeomorphic feedbacks at all three spatial scales (i.e., corridor, alluvial bar and micro-site) and at three different temporal scales, i.e., present, recent past and long term evolution on a diversified riparian landscape mosaic. We evaluate the performance and the limits of photogrammetric methods by targeting a set of fundamental parameters necessary to study biogeomorphic feedbacks at each of the three nested spatial scales and, when possible, propose appropriate solutions. The RMSE varies between 0.01 and 2 m depending on spatial scale and photogrammetric methods. Despite some remaining difficulties to properly apply them with current technologies under all circumstances in fluvial biogeomorphic studies, e.g. the detection of vegetation density or landform topography under a dense vegetation canopy, we suggest that photogrammetry is a promising instrument for the quantification of biogeomorphic feedbacks at nested spatial scales within river systems and for developing appropriate river management tools and strategies. [ABSTRACT FROM AUTHOR]

Native to West Africa, Spathodea campanulata (African tulip tree) is frequently viewed as a shade-intolerant invader. It commonly colonizes roadsides, human-disturbed forests, and abandoned agricultural land in tropical islands, where it can then become dominant in secondary forests. Some authors have suggested that the seedlings may be shade-tolerant and able to establish in closed-canopy forest, but the shade tolerance of seedlings has never been evaluated. We identified tolerated light environments of S. campanulata seedlings in wet forests in Hawai'i by measuring photosynthetically active radiation (PAR) around naturally occurring seedlings (<30 cm height) in the field. We also measured photosynthetic responses of seedlings to light under field and laboratory conditions and determined seedling growth rates in sun and shade. Seedlings were found in shaded conditions in the field, and they consistently had positive net carbon gain at 50 μmol photons m-2·sec-1 PAR, with an estimated mean compensation point below 10 μmol photons m· sec-1, indicating high shade tolerance. The most frequent midday light environments of S. campanulata seedlings in the field were in the range of 50 to 200 μmol photons m-2·sec-1PAR (i.e., 2.5% to 10% of full sunlight). Among seedlings found growing in shade, minimum saturating light (Ek), determined from chlorophyll fluorescence, averaged 260 μmol photons m-2·sec-1, suggesting that maximum seedling photosynthesis can occur at less than 13% of full sun. Growth rates of young seedlings in shade and sun were comparable. Widespread wind dispersal of seeds, seedling tolerance of low light, and our observations of some S. campanulata saplings establishing in rain forest without recent disturbance suggest that S. campanulata will be a persistent component of Hawaiian lowland rain forests. [ABSTRACT FROM AUTHOR]

Rivers have an intricate relationship with the vegetation that colonizes them. Riparian plants, capable of thriving within river corridors, both respond to and influence geomorphology. Yet interactions between river morphodynamics and vegetation tend to be context specific, making it challenging to generalize findings between locations. The current comprehension of vegetation interaction with physical processes, and especially its effects on river morphodynamics, still lacks clarity. This article examines numerous sources of variation in plant responses to, and effects on, river morphodynamics. Vegetation influences on geomorphological parameters vary in terms of intensity and spatial extent along the gradient of river energy and according to the fluvial style. Whilst feedbacks between vegetation and river morphodynamics are readily discernible at a local scale, on larger spatial scales, it can remain difficult to precisely determine cause-and-effect relationships that link hydrogeomorphic and vegetation drivers and the outcomes of their feedbacks. This is especially problematic for those feedbacks that give rise to emergent system landscape behaviour in meandering and island braided rivers. By contrast, in certain river configurations, such as anabranching rivers, the imprint of vegetation on the riverscape can be clearly evident. The imprint of vegetation is also supported by evidence from the ancient alluvial record. Through this review, we highlight key perspectives from a wide range of modern and ancient rivers of varied configuration in order to inform future studies of vegetation responses to, and effects on, river morphodynamics. • Vegetation responses to, and effects on, river morphodynamics are modulated by environmental and biological contexts. • Vegetation-geomorphology interactions are embedded into a complex adaptive system. • Vegetation drives discernible scale-dependent effects on geomorphology at the local scale (10-1 - 102 m). • Large scales: determining cause-and-effect relationships linking hydrogeomorphic and vegetation drivers remains challenging. • Vegetation: Insufficient but Non-redundant parts of Unnecessary but Sufficient (INUS) conditions for various river types. [ABSTRACT FROM AUTHOR]

The structure and function of riparian ecosystems generally result from feedbacks between plant dynamics and fluvial processes and landforms, i.e., river morphodynamics. Taxonomic approaches do not allow direct identification and quantification of the mechanisms involved in the interaction between plant communities and the geomorphological environment. Although riparian ecosystems show enormous taxonomic variations, comparable patterns of plant response traits across different taxa may evolve in response to the exposure to similar hydrogeomorphological processes in relation to flow dynamics, sediment transport, and nutrient and water availability. Biogeomorphological functional classifications for plant responses to, and effects on, river morphodynamics at the levels of individual plants, populations, and communities have been proposed in the literature. They serve herein as a basis for identifying and quantifying, within a presented standardized functional trait framework, key plant response and effect traits that can help to explain feedbacks between plants and morphodynamics. In particular, functional guilds and functional diversity metrics can be applied at the population and community levels for exploring feedbacks between vegetation and river morphodynamics worldwide. In this framework, the variability in plant effects across different environments and spatiotemporal scales, related to the biological characteristics of the plants (i.e., morphological reconfiguration of plants into the flow, seasonal phenology, phenotypic plasticity, and vegetation succession), can be explored. New opportunities including remote sensing and numerical modelling approaches, coupled with the inclusion of plant traits through our original framework, will improve our understanding of feedbacks between vegetation and morphodynamics and contribute to an improved prediction of biogeomorphological river trajectories. • Taxonomical approaches do not permit the analysis of plant-geomorphology feedbacks. • Functional traits links hydrological, geomorphological and biological drivers and processes which shape river systems. • Riparian plant traits converge despite taxonomic variation. • The functional trait approach is an opportunity for quantifying riparian vegetation-river interactions worldwide. • The functional trait approach can be supported by remote sensing and numerical modelling of river trajectories of change. [ABSTRACT FROM AUTHOR]

Abstract This work is the first geomorphological analysis of La Narse de la Sauvetat , a hydromorphic basin located in the southern Limagne plain (French Massif Central) which had never been studied despite its great palaeoenvironmental interest. We explore the potential of its sedimentary archives to provide valuable data on Holocene geomorphic dynamics and their sensitivity to local and regional hydro-climatic changes. In order to characterize the nature and the morphostratigraphic and pedosedimentary evolution of the basin, we used an integrative approach involving geomorphological mapping, hand auger stratigraphic cross-sections, topographic analysis based on LiDAR data and stereophotogrammetric reconstruction, geophysical prospection and radiocarbon dating. Results revealed a palaeotopography fossilized under 6 m of sedimentary infilling, with a clear shift from fluvial to hydromorphic conditions circa 2800 cal BCE, separated by a level with colluvial and lacustrine features. A detailed analysis of the eastern border of the basin also suggests the existence of a former open valley in place of the current closed depression, now locked in by a topographic threshold forming a dam. The sedimentary aggradation of the basin started with an alluvial phase during the Upper Pleistocene and probably continued into the Middle and Late Holocene, consistently with regional alluvial dynamics. In the early Subboreal, a massive landslide occurred on the western slopes of the Puy-de-Corent volcanic plateau, thereby damming the valley and forming a closed depression. This episode coincided with the mid-Holocene climatic shift and an associated phase of slope instability and increased landslides in Western Europe due to changing climatic conditions. This depression evolved into a hydromorphic basin with several high energy hydro-sedimentary episodes after 2800 cal BCE; however hydro-sedimentary conditions gradually became more stable towards the Late Holocene. Around 500 cal CE, the drainage deteriorated towards palustrine conditions and caused the formation of a marsh and its consequent evolution into a shallow lake throughout the Middle Ages. This lake was drained in the late XVIIIth Century. The long-term sedimentary record of La Narse de la Sauvetat , sensitive to climatic instability periods of the Middle Holocene, makes this landslide-dammed basin a valuable site with an important potential to further development of palaeoenvironmental and geoarchaeological studies. Graphical abstract Unlabelled Image Highlights • A palaeovalley was found under Pleistocene and Holocene alluvio-colluvial sediments. • A landslide dammed the valley in the early Subboreal, forming a short-lived lake. • The depression became hydromorphic between 2800 cal BCE and late Antiquity. • The basin was a marsh then a shallow lake during the Middle Ages. • La Narse de la Sauvetat has high potential for further palaeoenvironmental research. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the first results of the geoarchaeological study of an unusual hilltop wetland, located within the protohistoric proto‐urban site of Corent in the French Massif Central. This small depression offers an exceptionally local sedimentary record that provided valuable data on long‐term human–environment interactions, as well as proto‐urbanization of the first millennium B.C.E. Field survey revealed a major archaeological discovery: a large ensemble of 114 Iron Age storage pits excavated in clayey deposits. The geoarchaeological analysis of stratigraphic logs and cross‐sections completed by geophysical survey and radiocarbon dating allowed us to refine the chronology of these structures. Here, we suggest these structures are probably contemporary with the Hallstatt occupation of the site (600–425 B.C.E.), consistent with the emergence at Corent of a short‐lived proto‐urban environment during this period. These investigations also allowed us to characterize the main evolution phases of the basin and the diversity of human impacts from first disturbance in the Early Neolithic to its final destruction in the Roman period. These findings highlight the nonlinear nature of the socio‐environmental interactions and the definitive shift to an “anthroposystem” as a consequence of major disturbance in the first Iron Age, centuries before the development of urban settlements in the oppida period. [ABSTRACT FROM AUTHOR]

ALS-derived raster visualization techniques have become common in recent years, opening up new possibilities for subtle landform detection in earth sciences and archaeology, but they have also introduced confusion for users. As a consequence, the choice between these visualization techniques is still mostly supported by empirical knowledge. Some attempts have been made to compare these techniques, but there is still a lack of analytical data. This work proposes a new method, based on gradient modelling and spatial statistics, to analytically assess the efficacy of these visualization techniques. A selected panel of outstanding visualization techniques was assessed first by a classic non-analytical approach, and secondly by the proposed new analytical approach. The comparison of results showed that the latter provided more detailed and objective data, not always consistent with previous empirical knowledge. These data allowed us to characterize with precision the terrain for which each visualization technique performs best. A combination of visualization techniques based on DEM manipulation (Slope and Local Relief Model) appeared to be the best choice for normal terrain morphometry, occasionally supported by illumination techniques such as Sky-View Factor or Negative Openness as a function of terrain characteristics. [ABSTRACT FROM AUTHOR]

The development of the Neolithic way of life in the western Mediterranean during the sixth millennium cal. BC is the consequence of the spread of populations from the Near East after successive stages of cultural remodelling. Despite the clear contribution of the Near Eastern and Aegean Neolithic to the economic and technical changes that happened to the west, little is known here about their symbolic legacies, because of the scarcity of representations and ritual evidences associated to the earliest western Neolithic contexts. Excavations at the rock shelter of Pendimoun (southeastern France) yielded the first anthropomorphic stone sculpture from the western Mediterranean Neolithic (early sixth millennium cal. BC). Using both carving and painting techniques, it represents a realistic-looking human face and is a unique example within the western Mediterranean and European frameworks. After describing the shaping and colouring details of the mask, the authors here deal with its possible social significances and cultural connections. [ABSTRACT FROM PUBLISHER]

Abstract: Large tsunamis are major geomorphic crises, since they imply extensive erosion, sediment transport and deposition in a few minutes and over hundreds of kilometres of coast. Nevertheless, little is known about their geomorphologic imprints. The December 26, 2004 tsunami in Sumatra (Indonesia) was one of the largest and deadliest tsunamis in recorded human history. We present a description of the coastal erosion and boulder deposition induced by the 2004 tsunami in the Lhok Nga Bay, located to the West of Banda Aceh (northwest Sumatra). The geomorphological impact of the tsunami is evidenced by: beach erosion (some beaches have almost disappeared); destruction of sand barriers protecting the lagoons or at river mouths; numerous erosion escarpments typically in the order of 0.5–1.5 m when capped by soil and more than 2 m in dunes; bank erosion in the river beds (the retreat along the main river is in the order of 5–15 m, with local retreats exceeding 30 m); large scars typically 20–50 cm deep on slopes; dislodgement of blocks along fractures and structural ramps on cliffs. The upper limit of erosion appears as a continuous trimline at 20–30 m a.s.l., locally reaching 50 m. The erosional imprints of the tsunami extend to 500 m from the shoreline and exceed 2 km along riverbeds. The overall coastal retreat from Lampuuk to Leupung was 60 m (550,000 m2) and locally exceeded 150 m. Over 276,000 m3 of coastal sediments were eroded by the tsunami along the 9.2 km of sandy coast. The mean erosion rate of the beaches was ~30 m3/m of coast and locally exceeded 80 m3/m. The most eroded coasts were tangent to the tsunami wave train, which was coming from the southwest. The fringing reefs were not efficient in reducing the erosional impact of the tsunami. The 220 boulders measured range from 0.3 to 7.2 m large (typically 0.7–1.5 m), with weights from over 50 kg up to 85 t. We found one boulder, less than 1 m large, at 1 km from the coastline, but all the others were transported less than 450 m (<7 m a.s.l.). No fining landward boulder size distribution could be detected. The coincidence of different size modes, from boulders to fine sands, with independent spatial distributions, suggests that all the material was not transported in suspension, but rather by a combination of suspension and bed load transport. Finally, the spatial and size distributions of tsunami boulder deposits mostly depend on the location and characteristics of their source (coral reef, beach rock, platform, dams), together with clast and surface interference during transport. One year after, the coastal environment in northwest Sumatra is still in a post-tsunami dynamic. Thus, the difference between the largest tsunamis (height>30 m) and the moderate tsunamis (height<10 m) could be their long-term impact on coastal environments. [Copyright &y& Elsevier]