Runoff and Soil Erosion on Slope Cropland: A Review

Soil erosion has become a serious environmental problem worldwide, and slope land is the main source of soil erosion. As a primary cover of slope land, crops have an important influence on the occurrence and development of runoff and soil erosion on slope land. This paper reviews the current understanding of runoff and soil erosion on slope cropland. Crops mainly impact splash detachment, slope runoff, and sediment yield. In this review paper, the effects of crop growth and rainfall on the splash detachment rate and the spatial distribution of splash detachment are summarized. Crop growth has a significant impact on runoff and sediment yield. Rainfall intensity and slope gradient can influence the level of erosive energy that causes soil erosion. Furthermore, other factors such as antecedent soil water content, soil properties, soil surface physical crust, and soil surface roughness can affect soil anti-erodibility. The varying effects of different crops and with different influence mechanisms on runoff and soil erosion, as well as changes in their ability to influence erosion under different external conditions should all remain focal points of future research. The effect of crop vegetation on runoff and soil erosion on slope land is a very important factor in understanding large-scale soil erosion systems, and in-depth study of this topic is highly significant for both theory and practice.     

北京不同区域气溶胶辐射效应

采用大气辐射传输模式SES2以及2013年1月—2015年10月欧洲中期天气预报中心细网格再分析资料计算了北京地区4个观测站地面接收的短波辐射通量,分析了晴天和云天北京城郊气溶胶对总辐射的定量影响时空变化特征。结果表明:北京城区和近郊区气溶胶对总辐射的影响约为远郊区的2倍,北京南部和西部气溶胶对辐射的影响较大,晴天和云天北京城区和近郊区气溶胶对总辐射的削减值分别为146.23~180.99 W·m-2和202.11~217.02 W·m-2,晴天总辐射削减空间差异较大;秋冬季气溶胶对总辐射的影响明显大于春夏季,北京市观象台秋冬季气溶胶对总辐射的削减作用最大可达60%,较春夏季高10%~20%;北京城郊总辐射和直接辐射削减率与气溶胶光学厚度变化均呈线性关系,近地面PM_2.5浓度对辐射的影响不容忽视。     

Evolution and changes of permafrost on the Qinghai-Tibet Plateau during the Late Quaternary

Due to the uplift of Qinghai-Tibet Plateau(QTP), the cryosphere gradually developed on the higher mountain summits after the Neocene, becoming widespread during the Late Quaternary. During this time, permafrost on the QTP experienced repeated expansion and degradation. Based on the remains and cross-correlation with other proxy records such as those from glacial landforms, ice-core and paleogeography, the evolution and changes of permafrost and environmental changes on the QTP during the past 150,000 years were deduced and are presented in this paper. At least four obvious cycles of the extensive and intensive development, expansion and decay of permafrost occurred during the periods of 150–130, 80–50, 30–14 and after 10.8 ka B.P.. During the Holocene, fluctuating climatic environments affected the permafrost on the QTP, and the peripheral mountains experienced six periods of discernible permafrost changes:(1) Stable development of permafrost in the early Holocene(10.8 to 8.5–7.0 ka B.P.);(2) Intensive permafrost degradation during the Holocene Megathermal Period(HMP, from 8.5–7.0 to 4.0–3.0 ka B.P.);(3) Permafrost expansion during the early Neoglacial period(ca. 4,000–3,000 to 1,000 a B.P.);(4) Relative degradation during the Medieval Warm Period(MWP, from 1,000 to 500 a B.P.);(5) Expansion of permafrost during the Little Ice Age(LIA, from 500 to 100 a B.P.);(6) Observed and predicted degradation of permafrost during the 20 th and 21 st century. Each period differed greatly in paleoclimate, paleoenvironment, and permafrost distribution, thickness, areal extent, and ground temperatures, as well as in the development of periglacial phenomena. Statistically, closer dating of the onset permafrost formation, more identification of permafrost remains with richer proxy information about paleoenvironment, and more dating information enable higher resolution for paleo-permafrost reconstruction. Based on the scenarios of persistent climate warming of 2.2～2.6 °C in the next 50 years, and in combination of the monitored trends of climate and permafrost changes, and model predictions suggest an accelerated regional degradation of plateau permafrost. Therefore, during the first half of the 21 st century, profound changes in the stability of alpine ecosystems and hydro(geo)logical environments in the source regions of the Yangtze and Yellow rivers may occur. The foundation stability of key engineering infrastructures and sustainable economic development in cold regions on the QTP may be affected.     

Response of fish communities in rivers subjected to a high sediment load

Erosion and sediment yield are a significant problem in the Guadalquivir River basin. Such phenomena are largely driven by a land use devoted to intensive cultivation of olive trees, with a large socioeconomic influence in Andalusia. This sediment overload in rivers causes serious impacts on all fluvial ecosystem components.In this study we assess the chronic effect of sediment yield on fish communities at 104 river sites located in two different sub-catchments – the Bembézar and Guadajoz rivers – both with different lithological composition and erosion rates. Sediment yield was estimated using a semi-quantitative Factorial Score Model (FSM), developed specifically for Spanish rivers. The fish populations of both basins were evaluated in composition and abundances by the study of Fernández-Delgado et al., 2014. The influence of sediment yield on the fish community was analyzed using General Additive Models.The sediment yield was higher in the Guadajoz basin (921 T/Km2 per year) than in Bembézar (701 T/Km2 per year). In the former, fish communities were poorer in both fish density and diversity, with Luciobarbus sclateri as the only substantially present species and a significant relationship between sediment yield and load, and fish density. In contrast, in the Bembézar basin, sediment yield was correlated with total fish density, including Luciobarbus sclateri, Pseudochondrostoma willkommii, Cobitis paludica, Iberochondrostoma lemmingii, Anaecypris hispanica, and Cyprinus carpio. Intermediate values of sediment yield led to maximum densities, while those higher decreased the density of these species.     

MOTION AND INTENSITY AND IMPACT CHARACTERISTICS OF TROPICAL CYCLONE AFFECTING THE LIAODONG PENINSULA

Conventional data and the Yearbook on Tropical Cyclones (TC) data from 1971 to 2000 are used to study the climate and disaster features of TC affecting the Liaodong Peninsula. Results indicate that interannual change of TC activities is obvious. Different sources of TC have different impacts on the area of interest. Intensity and moving speed of TC vary substantially in the progress of northward movement. Besides, tracks and damage distributions of TC are quite different.     

Anthropogenic threat assessment of marine-associated fauna in Spencer Gulf,South Australia

Assessing the vulnerability of species to [anthropogenic threats is an essential step when developing management strategies for wild populations. With industrial development forecasted to increase in Spencer Gulf, South Australia, it is crucial to assess the ongoing effects of anthropogenic threats to resident and migratory species. Expert elicitation was used to assess 27 threats against 38 threatened, protected, and iconic marine-associated species. Species and threat interactions were assessed individually, and as taxonomic or functional groups. Climate change had the greatest overall exposure (c.f. risk) across species, followed by disturbance, pollution, disease/invasive species, and fishing/aquaculture threats. The largest overall sensitivities (c.f. consequences) were pollution and disease/invasive species, followed by climate change, disturbance and fishing/aquaculture threats. Vulnerability scores (exposure x sensitivity) showed the climate change group posing the greatest overall threat in Spencer Gulf, with individual climatic threats ranking as three of the top four biggest threats to most animal groups. Noise, shipping, and net fishing were considered the greatest region-specific individual threats to marine mammals; as were trawl fishing, line fishing, and coastal activities to fish/cuttlefish; trawl fishing, line fishing, and net fishing to elasmobranchs; and oil spill, disease, and coastal activities to sea/shorebirds. Eighteen of the 20 highest vulnerability scores involved the short-beaked common dolphin, Indo-Pacific bottlenose dolphin, and Australian sea lion, highlighting the particular susceptibility of these species to specific threats. These findings provide a synthesis of key threats and vulnerable species, and give management a basis to direct future monitoring and threat mitigation efforts in the region.     

地震岩问题

在过去的82年(1931—2013)中,共出现了39个成因术语。在这39个术语中,只有10个是真正沉积成因的(例如浊积岩),其他29个术语都是比较草率地提出的(just jargons;例如地震岩、海啸岩等)。“地震岩”(seismites)这一成因术语是赛拉赫(Seilacher,1969)提出的,它指沉积记录中的古地震。这是一个误用的(misnomer)术语。赛拉赫仅仅根据美国加利福尼亚州的中新统蒙特雷组(Miocene Montery Formation)10,m厚的露头观察,就匆忙地提出这个术语。他并未对这个露头进行认真的科学研究。最根本的问题是,地震是一个触动因素^①,并不是一个沉积作用。在古代的沉积记录中,鉴别不出各种触动因素(trigger)^②,因为自然界不能保留触动因素曾经存在过的证据。“软沉积物变形构造”(soft-sediment deformation structures,可简称为SSDS),通常被人们用来作为地震岩的鉴别标志,其实它是“液化作用”(liquefacation)的结果。液化作用可以由21种触动因素中的任何一种引起,其中包括地震(earthquake)、陨石冲击(meteorite impact)、海啸(tsunami)、沉积负载(sediment loading)等。在死海盆地中的角砾碎屑,所谓典型的由地震引起的沉积,实际上是常见的同沉积作用的碎屑流的产物,与地震没有关系。其他类型的SSDS,例如 “双向叠层构造”(duplex-like structures)和碎屑注入体(clastic injections),也可以说是同沉积作用的产物,与地震没有关系。世界上广泛分布的砂岩储油层,包括墨西哥湾、北海、挪威海、尼日利亚、赤道几内亚、加逢、孟加拉湾,都表明这些地区的SSDS的第一起因(primary cause)是沉积负载,其证据是可以观察到的和令人信服的。海啸及陨石冲击,都可以形成大量的沉积,例如SSDS的侧向延伸(lateral extent of SSDS),但这些沉积都不能当作地震的鉴别标志。位于印度东部大陆边缘的Krishna-Godavari(KG)盆地中的SSDS,是多种触动因素^①引起的沉积物的失控和液化作用的结果,即多成因的SSDS。由于这些原因,“地震岩”这个成因术语确实没有什么科学价值,应当废弃。     

Recent shifts in coastline change and shoreline stabilization linked to storm climate change

Since cuspate coastlines are especially sensitive to changes in wave climate, they serve as potential indicators of initial responses to changing wave conditions. Previous work demonstrates that Cape Hatteras and Cape Lookout, North Carolina, which are largely unaffected by shoreline stabilization efforts, have become increasingly asymmetric over the past 30 years, consistent with model predictions for coastline response to increases in Atlantic Ocean summer wave heights and resulting changes in the distribution of wave‐approach angles. Historic and recent shoreline change observations for Cape Fear, North Carolina, and model simulations of coastline response to an increasingly asymmetric wave climate in the presence of beach nourishment, produce comparable differences in shoreline change rates in response to changes in wave climate. Results suggest that the effect of beach nourishment is to compensate for – and therefore to mask – natural responses to wave climate change that might otherwise be discernible in patterns of shoreline change alone. Therefore, this case study suggests that the effects of wave climate change on human‐modified coastlines may be detectable in the spatial and temporal patterns of shoreline stabilization activities. Similar analyses of cuspate features in areas where the change in wave climate is less pronounced (i.e. Fishing Point, Maryland/Virginia) and where local geology appears to exert control on coastline shape (i.e. Cape Canaveral, Florida), suggest that changes in shoreline configuration that may be arising from shifting wave climate are currently limited to sandy wave‐dominated coastlines where the change in wave climate has been most pronounced. However, if hurricane‐generated wave heights continue to increase, large‐scale shifts in patterns of erosion and accretion will likely extend beyond sensitive cuspate features as the larger‐scale coastline shape comes into equilibrium with changing wave conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

中南半岛森林覆被变化研究进展

中南半岛森林覆被是热带地区极为重要的自然资源,对当地生态环境和社会经济发展都有重要影响。本文从遥感监测与制图、时空变化格局、影响因素和生态环境效应4 个方面,系统总结和评述了中南半岛森林覆被变化的研究进展,并对研究问题和发展方向进行了讨论。研究表明：①中南半岛森林覆被遥感监测数据源由光学遥感逐渐转向雷达遥感,监测方法向采用多分类器和多源信息转变,监测对象主要是天然森林覆被,人工林监测仍面临多重困难;②1980-2010 年期间,中南半岛不同地区森林覆被变化时空差异明显,其中,在1990 年前森林覆被面积为净增加,之后净减少;在空间上,泰国、老挝、缅甸和柬埔寨森林面积在1990 年后均持续减少,只有越南呈增长趋势;③中南半岛森林覆被变化的直接驱动因素主要为经济林扩张、刀耕火种农业、道路建设和商业采伐,间接驱动因素包括人口、社会经济和政策等因素,主要表现为森林数量变化、森林退化和森林再生/恢复等方面,其程度与干扰方式、强度、频率直接相关;④中南半岛森林覆被变化的生态环境效应主要体现在水分效应、大气环境效应、土壤效应和生物效应4方面。     

村落遗产地社区居民旅游发展态度的影响因素

构建了社区依恋、社区关注、社区参与、旅游影响感知和社区居民旅游发展态度的结构关系模型,并以村落遗产地——福建土楼为例,采用结构方程模型（SEM） 验证社区居民旅游发展态度的影响因素,并引入个人获益作为调节变量,剖析在获益居民和没有获益的居民中,各种旅游感知对旅游发展态度的影响是否存在显著差异。研究结果表明：① 经济获益感知、社会文化获益感知和环境获益感知均对态度具有显著正向影响,而经济成本感知对态度具有显著负向影响;② 社区依恋通过社会文化获益感知和环境获益感知对态度产生间接影响;③ 社区关注通过经济获益感知和环境获益感知间接影响态度,并通过经济成本感知间接影响态度;④ 社区参与通过经济获益感知、社会文化获益感知和环境获益感知对态度产生间接正向影响,并通过经济成本感知对态度产生间接负向影响;⑤ 经济获益感知、社会文化获益感知和环境获益感知对态度的影响对获益居民比没有获益的居民要大,而经济成本感知、社会文化成本感知与环境成本感知对态度的影响对没有获益的居民比获益居民要大。