The Role of Fire Disturbance on Runoff and Erosion Processes – a Long‐Term Approach,Mt. Carmel Case Study,Israel

The Mediterranean ecosystem of Mt. Carmel, Israel, is subjected to an increasing number of forest fires of various extents and severities. The impacts of forest fires on runoff and erosion are widely documented and include increased peak flows and soil loss until the return of a vegetation cover. Most studies, however, treat fire as a single event, whereas the present study is aimed at exploring the long‐term effects of repeated forest fires on eco‐geomorphic processes. The study integrates the results of plot‐based, detailed analysis of post‐fire runoff and erosion with vegetation recovery analysis, at a temporal‐spatial scale which includes the effect of reburning. Our results indicate that forest fires lead to a significant increase in runoff and sediment yields, particularly during the first two years following the disturbance, up to five orders of magnitude higher than from the adjacent unburnt control plots.     

Soil fertility and slope processes in the Western Cumberland Escarpment of Kentucky: influences on the development of horticulture in the Eastern Woodlands

The archaeological record of dry rockshelters in the Red River Valley of eastern Kentucky contains botanical remains of several weedy annual seed-bearing plants that point to the independent development of agriculture during the Late Archaic and Early Woodland Period. The objective of this study is to gather quantitative data through the chemical and physical analysis of soils collected within a valley transect to gain insights into landscape processes and soil fertility that may have played a role in the early development of plant domestication and the location of garden plots in relation to rock shelter sites in the upper Cumberland Plateau region of eastern Kentucky. Soils on upland benches formed in limestones have soil fertility values that are comparable to fertile floodplain soils. Upslope outcrops of calcareous bedrock are contributing basic cations to these bench soils. Additionally, in comparison to other landscape positions these upland soils have high levels of organic carbon, available P and greater C:N ratios. Soil morphology, radiocarbon dates, and archaeological evidence indicate that many of the numerous earthflows and debris flows within the region are Early to Middle Holocene in age. These slides were likely generated by Mid-Holocene climatic shifts in which the frequency and intensity of summer precipitation increased across the southeastern United States. These slope failures may have contributed to the development of plant domestication by creating forest canopy gaps and disturbed soils in which weedy plants thrived.     

Estimation of Soil Erosion Using Field and Modelling Approaches in an Undisturbed Arnhem Land Catchment,Northern Territory,Australia

An assessment of slope erosion at Tin Camp Creek catchment, Arnhem Land, Northern Territory, Australia, was carried out using the fallout environmental radioisotope caesium‐137 (¹³⁷Cs) as an indicator of soil erosion status, two numerical models (SIBERIA and the Revised Universal Soil Loss Equation (RUSLE)) and erosion pins. This undisturbed drainage basin is situated in the seasonally wet‐dry tropics, with high energy storms and a mean annual rainfall of 1389 mm. Tin Camp Creek catchment is unaffected by European agriculture or pastoral activities, but often experiences fire during the dry season. Two transects were sampled for ¹³⁷Cs in 2002 and 2004, and two models were used to convert ¹³⁷Cs measurements into soil loss estimates. Two methods using the theoretical Profile Distribution Model (PDM) gave net soil redistribution rates between +2.72 and –22.19 t ha^?1 yr^?1 and +2.95 and –24.06 t ha^?1 yr^?1, respectively, while an Australian empirical model (AEM) for uncultivated soils produced estimates between +1.84 and –7.00 t ha^?1 yr^?1 (negative values indicate soil erosion, positive, deposition). The RUSLE gave estimated soil losses for the two transects of approximately 10 t ha^?1 yr^?1, while the SIBERIA model produced values between 0.5 and 2 t ha^?1 yr^?1 for the transects and between 3.5 and 11 t ha^?1 yr^?1 for the total catchment. Average net soil losses of 14 and 15 t ha^?1 yr^?1 for the total catchment and slopes, respectively, were measured by erosion pins. The soil losses in the catchment are similar to those for some other transects in the Northern Territory and the Kimberley region of Western Australia (measured by the ¹³⁷Cs AEM), even though these areas are affected by pastoral activities. This may be at least partly explained by erosion in Tin Camp Creek catchment during high intensity rainstorms at the commencement of the wet season, especially if the slopes have been affected by fire during the previous dry season.     

陕北明长城夯土密度与雨蚀破坏的量化研究

为量化研究夯土性质对陕北明长城遗址雨蚀破坏模式的影响作用,采用室内模拟降雨试验的方法对夯土密度和雨蚀量间的关系进行定量化分析。研究结果显示,大到暴雨条件下,干湿作用产生的破坏是低强度夯土(密度1.5 g·cm^-3、1.6 g·cm^-3)最主要的雨蚀破坏模式,冲刷破坏造成的雨蚀量较小;水力侵蚀产生的冲刷破坏和重力侵蚀引起的小范围掉块是高强度夯土(密度1.7~1.9 g·cm^-3)最主要的破坏模式,冲刷破坏造成的雨蚀量较大;当土体含水率在3%~7%区间时,夯土的雨蚀量和密度呈指数函数关系,二者呈现正相关性。研究结果为探索多因素作用下夯土雨蚀的破坏机制提供方法借鉴,是土遗址病害研究的重要组成部分。     

结合热力学对古建筑墙体砖(雕)风化侵蚀机理探究

为了揭示古砖的风化侵蚀机理,采用X射线衍射法(XRD)、X射线荧光光谱法(XRF)、扫描电子显微镜观察(SEM)进行微观结构分析,结合压汞仪测试孔的性质,并使用热力学软件(HSC)对砖内的化学反应进行验证。研究结果表明:对于靠近地面一定高度内的古建筑墙体砖,地下水及离子通过砖内的毛细管网络不断向上部和表面进行迁移,在砖内可溶性盐类的结晶以及水结冰时产生的压力是造成墙体砖风化破坏的主要因素;对于NO X、SO 2浓度较高、酸雨较多的地区,酸性物质进入砖体并与钾长石,钠长石等发生反应形成新的盐类,盐的结晶、溶解、流失也是导致古砖破坏的一个不可忽略的因素,尤其是对于地下水无法渗透到的墙体砖,这些可能成为主要的物理化学损毁因素。本研究为古砖以后的保护提供了一种新的研究思路以及科学的理论基础。     

Micromorphology of Pech-de-l'Azé II sediments

A micromorphological study of the sediments from the cave of Pech-de-l'Azé II using the terminology of Brewer (1964) was undertaken in order to describe them, to compare the results and their palaeoclimatic interpretations (e.g., Laville, 1973) with those of classical sedimentological analyses and to evaluate the role of micromorphology in the analysis of cave and rock-shelter deposits.The soil skeleton is composed of quartz sand and silt resulting principally from the decay of bedrock with local reworking by solifluction and ruissellement. Lithorelicts consist of bedrock fragments of cryoclastic origin and detrital phosphate grains which can be identified as being large carnivore (bear or hyaena?) coprolites. The plasma is composed of mostly iron rich clay and although it was most abundant in reddish layers of previously recognized soils, no micromorphological evidence for clay illuvation was found. The latter might have been caused by post-depositional destruction by freeze and thaw which produced the generally well developed banded fabrics in many of the beds. Free grain argillans occur sporadically but are particularly well developed on phosphate grains. Secondary calcite, occurring either in dispersed zones or as void calcitans and neocalcitans occurs throughout but is more marked in the upper layers and bed 6.Micromorphologically based palaeoclimatic interpretations agreed on the whole with those obtained by classical sedimentology although several questions were raised which should make us more cautious in interpreting “classical” data: such as the origin of the clay, especially in “soil” horizons. The advantages of micromorphology in delineating sequence of events were indicated.     

POTENTIAL IMPACTS OF GLOBAL SEA-LEVEL RISE ON CANADIAN COASTS

The sea-level rise that may result from global climate change is placed within the context of past and present sea-level changes on Canadian coasts. To assess future impact, a dimensionless index of sensitivity is determined. Coasts with low, moderate, and high sensitivity constitute 67%, 30%, and 3% of the total coastline, respectively. The most sensitive regions are: (1) several parts of the Maritime Provinces; (2) two areas of the British Columbia coast; and (3) a large part of the Beaufort Sea coast. Impacts in four regions - Bay of Fundy, Beaufort Sea, Fraser Delta, and Eastern Shore of Nova Scotia - are discussed in detail. It is argued that the societal response to changes in sea level should favour retreat and accommodation strategies.
Il est possible que les changements climatiques globaux provoqueront une élévation du niveau de la mer. Nous examinons ce scénario dans le contexte des changements passés et présents du niveau de la mer sur les côtes canadiennes. Pour évaluer l'impact de l'élévation prévue un indice non dimensionnel de vulnérabilité est déterminé. Les côtes à la vulnérabilité basse, modérée et élevée constituent, respectivement, 67%, 30%, et 3% de tout le littoral. Les régions les plus vulnérables sont: (1) plusieurs régions dans les provinces maritimes; (2) deux zones sur la côte de la Colombie britannique; et (3) la plupart de la côte de la mer de Beaufort. Nous discutons en détail les impacts dans quatre régions, soit la baie Fundy, la mer Beaufort, la delta du Fraser et la rivage dit 'Eastern Shore' de la Nouvelle-Écosse. Nous estimons que la réponse sociale aux changements du niveau de la mer devrait favoriser des stratégies de retraite et d'accommodement.     

Surveying Coastal Archaeological Sites Damaged by Hurricane Sandy in Rhode Island,USA

Supported by the U.S. National Park Service's Historic Preservation Fund program, the Rhode Island Historical Preservation and Heritage Commission administered surveys of coastal archaeological sites damaged by 2012's Hurricane Sandy in Rhode Island, USA. This project documented the transformative effects of Hurricane Sandy on coastal archaeological sites, evaluated the eligibility of many of those sites for listing in the National Register of Historic Places, and provided new insights into ancient Native American coastal occupation. Notable project limitations include incomplete property access, bureaucratic delays, and a Tribal collaboration that fell short. Because preserving most of these erosion-prone sites through shoreline stabilization is unlikely, management efforts will consider preemptive archaeological salvage excavations. This case study may prove useful to archaeologists worldwide who are managing coastal sites threatened by rising sea levels and storms of increasing intensity and frequency.