Off road vehicle impact in Cape Cod national seashore: Disruption and recovery of dune vegetation

An on-going investigation of the rates of vegetation breakdown and natural recovery under controlled conditions has been established at Cape Cod National Seashore, Massachusetts, U.S.A. In this study, the effects of controlled impacts on a variety of coastal habitats were measured in terms of above and below ground biomass. Dune sites, ranging from unstabilized to moderately stabilized, were driven on at varying levels of intensity and along different exposures relative to slope and prevailing wind direction. Preliminary evidence suggests that a single summer season of driving (300–700 passes) on a confined track through dense stands ofAmmophila vreviligulata, Arctostaphylos uva-ursi, andDeschampsia flexuosa, can completely destroy the above-ground portions but leave adequate underground roots and thizomes for a small amount of vegetative regrowth after cessation of impact in the late summer and fall. Large differences in wind speed at ground level have been noted in driving tracks with different alignments relative to wind direction. Deflation rates may be excessive in tracks devoid of above ground cover and aligned parallel to strong prevailing winter winds.Presented at the Seventh International Biometeorological Congress, 17–23 August 1975, College Park, Maryland, USA.     

Research on the Risk Level of Landfall Typhoons in Zhejiang,China

Zhejiang Province, as a major province of economic strength in China, has economically well-developed coastal areas, which are heavily damaged during landfall typhoons. In this paper, typhoons that could cause serious damages to Zhejiang Province will be labeled as “disastrous typhoons,” and the corresponding wind velocities will be labeled as “disastrous wind velocities.” It is suggested that typhoons exceeding certain threshold-values be selected as samples for calculation, and this method is called threshold-value sampling. According to the typhoon measurement data and by using the P-III distribution function, the disastrous wind velocity of certain recurrence interval in typhoon-resistant and engineering design projects was calculated. The calculation results show that the disastrous wind velocity of the largest landfall typhoon of coastal areas for the next 10 years is 41.8 m/s, the disastrous wind velocity in the next 50 years is 49.7 m/s, and 52.9 m/s in the next 100 years. It can be seen at the same time that the wind velocity calculated by the P-III distribution model is more similar to the actual conditions compared to the wind velocity calculated by the Weibull distribution model. This method is conceptually clear, easy to use, and generates ideal results.     

Climate factors influencing bacterial count in background air samples

Total (as opposed to culturable) bacterial number counts are reported for four sites in the United Kingdom measured during campaigns over four separate seasons. These are interpreted in relation to simple climatic factors, i.e. temperature, wind speed and wind direction. Temperature has a marked effect at all four sites with data for a rural coastal site conforming best to a simple exponential model. Data for the other rural and urban locations show a baseline similar to that determined at the coastal rural location, but with some very significant positive excursions. The temperature dependence of bacterial number is found to conform to that typical of bacterial growth rates. At the coastal rural location, bacterial numbers normalised for temperature show no dependence on wind speed whilst at the inland sites there is a decrease with increasing wind speed of the form expected for a large area source. Only one site appeared to show a systematic relationship of bacterial concentrations to wind direction that being a site in the suburbs of Birmingham with highest number concentrations observed on a wind sector approaching from the city centre. PCR techniques have been used to identify predominant types of bacteria and results are presented which show that Bacillus was the dominant genus observed at the three inland sites during the winter and summer seasons. Pseudomonas appeared with comparable frequency at certain sites and seasons. There was in general a greater diversity of bacteria at the coastal site than at the inland sites.     

Wind Speed Perception and Risk

Background

How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human–wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people''s ability to estimate extreme wind speeds and perceptions of their associated risks.

Method

We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt.

Results

Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual–perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms.

Conclusion

These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.     

极值分布理论在广东寒害重现期预测中的应用

寒害是广东省继洪涝、台风之后的第三大灾害性天气,预测寒害重现期对科学防寒减灾具有实际意义.本研究基于广东省86个县(市)气象站1961-2015年冬季(12月-翌年2月)逐日气象资料,以积寒指数为寒害指标,采用Gumble分布、Weibull分布、对数正态分布和Pearson-Ⅲ型分布4个模型对各站寒害极值进行概率分布拟合,并检验筛选最优模型,计算不同重现期的寒害极值.结果表明: 广东省86个县(市)气象站中,有77个站适用Pearson-Ⅲ型分布,8个站适用对数正态分布,1个站用Gumble分布拟合最佳,Weibull分布函数不适用于广东寒害极值分布的拟合.根据各站最优拟合分布函数,预测广东86个站点10、25、50和100年寒害重现期,其相对误差均较小(≤6%);其多年一遇的积寒极值呈明显的纬向分布特征,表现为北多南少,与寒害发生过程中最低气温、平均气温、降温幅度等分布特征一致.研究成果可为广东相关行业科学防寒提供依据.     

The Influence of Topographic and Dynamic Cyclic Variables on the Distribution of Small Cetaceans in a Shallow Coastal System

The influence of topographic and temporal variables on cetacean distribution at a fine-scale is still poorly understood. To study the spatial and temporal distribution of harbour porpoise Phocoena phocoena and the poorly known Risso’s dolphin Grampus griseus we carried out land-based observations from Bardsey Island (Wales, UK) in summer (2001–2007). Using Kernel analysis and Generalized Additive Models it was shown that porpoises and Risso’s appeared to be linked to topographic and dynamic cyclic variables with both species using different core areas (dolphins to the West and porpoises to the East off Bardsey). Depth, slope and aspect and a low variation in current speed (for Risso’s) were important in explaining the patchy distributions for both species. The prime temporal conditions in these shallow coastal systems were related to the tidal cycle (Low Water Slack and the flood phase), lunar cycle (a few days following the neap tidal phase), diel cycle (afternoons) and seasonal cycle (peaking in August) but differed between species on a temporary but predictable basis. The measure of tidal stratification was shown to be important. Coastal waters generally show a stronger stratification particularly during neap tides upon which the phytoplankton biomass at the surface rises reaching its maximum about 2–3 days after neap tide. It appeared that porpoises occurred in those areas where stratification is maximised and Risso’s preferred more mixed waters. This fine-scale study provided a temporal insight into spatial distribution of two species that single studies conducted over broader scales (tens or hundreds of kilometers) do not achieve. Understanding which topographic and cyclic variables drive the patchy distribution of porpoises and Risso’s in a Headland/Island system may form the initial basis for identifying potentially critical habitats for these species.     

Responses of Terrestrial Ecosystems’ Net Primary Productivity to Future Regional Climate Change in China

The impact of regional climate change on net primary productivity (NPP) is an important aspect in the study of ecosystems’ response to global climate change. China’s ecosystems are very sensitive to climate change owing to the influence of the East Asian monsoon. The Lund–Potsdam–Jena Dynamic Global Vegetation Model for China (LPJ-CN), a global dynamical vegetation model developed for China’s terrestrial ecosystems, was applied in this study to simulate the NPP changes affected by future climate change. As the LPJ-CN model is based on natural vegetation, the simulation in this study did not consider the influence of anthropogenic activities. Results suggest that future climate change would have adverse effects on natural ecosystems, with NPP tending to decrease in eastern China, particularly in the temperate and warm temperate regions. NPP would increase in western China, with a concentration in the Tibetan Plateau and the northwest arid regions. The increasing trend in NPP in western China and the decreasing trend in eastern China would be further enhanced by the warming climate. The spatial distribution of NPP, which declines from the southeast coast to the northwest inland, would have minimal variation under scenarios of climate change.     

Historical distribution patterns of trigonioidids (non-marine Cretaceous bivalves) in Asia and their palaeogeographic significance

The non-marine trigonioidid bivalves show five phases of radiation in the Cretaceous of Pal-Asia: pre-Aptian (?Valanginian/Hauterivian–Barremian), Aptian, Albian, Cenomanian and Turonian–Maastrichtian. Their distribution patterns show two distinct palaeo-river systems feeding trigonioidids. Before the Cenomanian, the river system occupied the southwestern–southern–southeastern Pal-Asian continental margin areas. During the Turonian–Maastrichtian, it extended along the line of southcentral China−eastern China−northeastern China−northern China and Mongolia−northwestern China–eastern Fergana Basin of Kyrgyzstan−western Tajikistan Basin of Tajikistan–Tashkent area of Kazakhstan−central Kyzylkum of northern Uzbekistan–Aral Sea area of Kazakhstan. Furthermore, the general trigonioidid distribution pattern demonstrates that Japan was probably attached to part of eastern China and/or Korea during the ?Valanginian/Hauterivian–Cenomanian stages.     

Weather conditions during hunting season affect the number of harvested roe deer (Capreolus capreolus)

Due to human‐induced climate and landscape changes, distribution and abundance of many ungulate species have increased worldwide. Especially in areas where natural predators are absent, hunting is the essential management tool for regulating ungulate populations. Therefore, understanding the factors associated with harvest rates is the first step toward an adaptive management approach. Weather influences hunter and ungulate behavior and thus presumably harvest, but how and which meteorological parameters are linked to harvest numbers have rarely been evaluated. We used nearly 65,000 “sit and wait” and driven hunt harvests of roe deer (Capreolus capreolus) in Bavaria, Germany, and weather data from 2008 to 2017 to test for factors affecting roe deer harvests (i.e., temperature, rain hours, wind speed, sunshine duration, snow depth, workdays vs. weekends, month) using zero‐inflated negative binomial mixed‐effect models. Our results reveal that, besides workdays, high temperatures and prolonged rain resulted in fewer harvested animals, whereas sunshine duration in summer and snow height in snow‐rich areas partially favored harvests during sitting hunts in summer and winter, respectively. The influence of wind speed varied over the course of the year. In summer and autumn, wind speed commonly had a negative effect, positively affecting harvests in winter in some regions. Daily harvest numbers decreased during the summer and autumn hunting periods (May till mid‐October), while they increased during the winter period (mid‐October till mid‐January). Interestingly, harvest success during driven hunts, which are planned well in advance and therefore take place largely independent of weather conditions, was similarly affected by the weather. This result suggests that the inferred weather influence is not only due to the hunters'' decisions but also due to deer behavior. Since many ungulate populations may further benefit from climate change, building an understanding of the relationship between hunting success and weather will aid adaptive ungulate management.     

Know your limits? Climate extremes impact the range of Scots pine in unexpected places

Background and Aims Although extreme climatic events such as drought are known to modify forest dynamics by triggering tree dieback, the impact of extreme cold events, especially at the low-latitude margin (‘rear edge’) of species distributional ranges, has received little attention. The aim of this study was to examine the impact of one such extreme cold event on a population of Scots pine (Pinus sylvestris) along the species’ European southern rear-edge range limit and to determine how such events can be incorporated into species distribution models (SDMs).Methods A combination of dendrochronology and field observation was used to quantify how an extreme cold event in 2001 in eastern Spain affected growth, needle loss and mortality of Scots pine. Long-term European climatic data sets were used to contextualize the severity of the 2001 event, and an SDM for Scots pine in Europe was used to predict climatic range limits.Key Results The 2001 winter reached record minimum temperatures (equivalent to the maximum European-wide diurnal ranges) and, for trees already stressed by a preceding dry summer and autumn, this caused dieback and large-scale mortality. Needle loss and mortality were particularly evident in south-facing sites, where post-event recovery was greatly reduced. The SDM predicted European Scots pine distribution mainly on the basis of responses to maximum and minimum monthly temperatures, but in comparison with this the observed effects of the 2001 cold event at the southerly edge of the range limit were unforeseen.Conclusions The results suggest that in order to better forecast how anthropogenic climate change might affect future forest distributions, distribution modelling techniques such as SDMs must incorporate climatic extremes. For Scots pine, this study shows that the effects of cold extremes should be included across the entire distribution margin, including the southern ‘rear edge’, in order to avoid biased predictions based solely on warmer climatic scenarios.     

Analysis of Precipitation Characteristics during 1957-2012 in the Semi-Arid Loess Plateau,China

Precipitation is the only water supply and most important factor affecting vegetation growth on the slopes of semi-arid Loess Plateau of China. Based on precipitation data from 7 synoptic stations in the study area over the period 1957–2012, the trends of precipitation and standardized precipitation index (SPI) were analyzed by using linear regression, Mann−Kendall, and Spearman’s Rho tests at the 5% significance level. The results show that (1) the precipitation fluctuation of monthly precipitation was intense (coefficients of variation> 100%), and the drier years were recorded as 1965 and 1995 at all stations. (2) The significant change trend of different stations varied on different time scales: the Changwu station had a significant decreasing trend in April (−0.488 mm/year) and November (−0.249 mm/year), while Luochuan station was in April (−0.457 mm/year); Changwu station displayed a significant increasing trends in winter (0.220 mm/year) and a significant decreasing trends in spring (−0.770 mm/year). The significant decreasing trends in annual precipitation were detected at the Suide (−2.034 mm/year) and Yan’an (–2.129 mm/year) stations. (3) The SPI−12 series analysis suggests that the drought degree of Yulin and Changwu was the lowest and that of Hengshan was the highest among the 7 synoptic stations.     

Flight thresholds and seasonal variations in flight activity of the light-brown apple moth,Epiphyas postvittana (Walk.) (Tortricidae), in Victoria,Australia

Summary The flight activity of Epiphyas postvittana was studied at two sites near Melbourne with the aid of suction traps, over a period of 4 years. Maximum numbers were found to fly during the period September to March with peak activity coinciding with the emergence of winter, spring and summer generation moths. E. postivittana is predominantly a nocturnal flier with maximum activity around 20.00–24.00 h. The lower temperature threshold of flight was 8–11°C. The upper temperature threshold varied from 20–21°C, 24–25°C and 27–28°C for the winter, spring and summer generation moths respectively. Flight was highly influenced by the prevailing wind. The lower wind speed threshold was 0.5–0.8 m^-s and the upper wind speed threshold was 2.6–2.7 m^-s. The relationship between wind speed and the amount of flight was non-linear, with the frequency of flights decreasing sharply with increasing wind speed. No flights occurred at wind speeds greater than 2.8 m^-s. Variation in relative humidity had no influence on flight, but lack of rain favoured flight. The amount of flight activity and the amount of rainfall were negatively correlated; flights did not occur when the daily precipitation exceeded 32.5 mm, and with a precipitation exceeding 39 mm no flights could be expected. The value of these findings to pest control programmes is discussed.     

Pelagic larvae of benthic gastropods from shallow Antarctic waters of Admiralty Bay,King George Island

The occurrence, distribution and summer variation of pelagic larvae of benthic gastropods in the shallow coastal area of Admiralty Bay were determined for the summers of 1993/1994, 1994/1995 and 1996/1997 from plankton samples taken at 15- to 30-m depths in 12 stations. Significant differences were found among years at the end of January and February. Results of Principal Component Analysis showed the inverse relation of high wind speed and abundance of gastropod larvae in the three austral summers sampled, and suggested that environmental conditions prevalent during 1994/1995 and 1995/1997 were similar and differed from those of 1993/1994, which may have influenced the number of larvae observed.     

1961—2010年安徽省参考作物蒸散时空变化特征及成因

基于联和国粮农组织推荐的Penman Monteith公式和60个台站1961—2010年逐日气象观测资料,估算了安徽省的参考作物蒸散量(ET₀),在对ET₀空间分布特征和时间演变规律进行分析的基础上,定量探讨了安徽省影响ET₀变化的主导因素.结果表明: 研究期间,安徽省ET₀的年平均值约为878.58 mm·a^-1,夏季最大,冬季最小.年平均ET₀呈现由北向南、由低海拔向高海拔递减的空间分布特征.ET₀的变化主要归因于日照时数和风速,而气温和相对湿度的作用较小.由于日照时数和风速的共同负贡献明显超过气温和相对湿度的共同正贡献,导致安徽省ET₀整体上以-1.61 mm·a^-1的速率显著下降.ET₀在春季呈不显著的微弱上升趋势;夏季ET₀以-1.37 mm·a^-1的速率显著下降;秋、冬季的ET₀微弱下降,但趋势不显著.春、秋、冬季ET₀变化的主导因子是风速;夏季的主导因子是日照时数.ET₀变化的主导因子存在明显空间差异.有36.7%站点的年平均ET₀变化的主导因子是风速,主要分布在淮北南部和沿淮地区;其他大部分地区的主导因子都是日照时数.
     

A Linear City Model with Asymmetric Consumer Distribution

The article analyzes a linear-city model where the consumer distribution can be asymmetric, which is important because in real markets this distribution is often asymmetric. The model yields equilibrium price differences, even though the firms’ costs are equal and their locations are symmetric (at the two endpoints of the city). The equilibrium price difference is proportional to the transportation cost parameter and does not depend on the good''s cost. The firms'' markups are also proportional to the transportation cost. The two firms’ prices will be equal in equilibrium if and only if half of the consumers are located to the left of the city’s midpoint, even if other characteristics of the consumer distribution are highly asymmetric. An extension analyzes what happens when the firms have different costs and how the two sources of asymmetry – the consumer distribution and the cost per unit – interact together. The model can be useful as a tool for further development by other researchers interested in applying this simple yet flexible framework for the analysis of various topics.     

Brown planthopper Nilaparvata lugens was concentrated at the rear of the typhoon Soudelor in Eastern China in August 2015

Sometimes, extreme weather is vital for the population survival of migratory insects by causing sudden population collapse or outbreak. Several studies have shown that rice planthopper migration was significantly influenced by typhoons in eastern Asia. Most typhoons occur in the summer, especially in August. In August, brown planthopper Nilaparvata lugens (Stål) migrates northward or southward depending on wind direction, and thus typhoons can potentially influence its migration process and population distribution. However, this has not yet been studied. This paper reported a case study on the effects of Typhoon Soudelor on the summer migration of N. lugens in eastern China in 2015. The migration pathways of N. lugens were reconstructed for the period under the influence of a typhoon by calculating the trajectories and migration events in eight counties of the Yangtze River Valley region with ancillary information. Trajectory modelling showed that most migrants took short distance migrations (less than 200 km) under the influence of the Typhoon Soudelor. Numerous N. lugens migrants were concentrated and deposited at the rear of the typhoon during the last 5 days of Typhoon Soudelor on August 9–13 due to horizontal convergence, and this led to an outbreak population. These results indicated that the N. lugens population was redistributed by the typhoon in the summer and that the population dynamics at the rear of a typhoon should be kept under close surveillance. This study provided insight into migratory organisms adapting to atmospheric features.     

Commuting fruit bats beneficially modulate their flight in relation to wind

When animals move, their tracks may be strongly influenced by the motion of air or water, and this may affect the speed, energetics and prospects of the journey. Flying organisms, such as bats, may thus benefit from modifying their flight in response to the wind vector. Yet, practical difficulties have so far limited the understanding of this response for free-ranging bats. We tracked nine straw-coloured fruit bats (Eidolon helvum) that flew 42.5 ± 17.5 km (mean ± s.d.) to and from their roost near Accra, Ghana. Following detailed atmospheric simulations, we found that bats compensated for wind drift, as predicted under constant winds, and decreased their airspeed in response to tailwind assistance such that their groundspeed remained nearly constant. In addition, bats increased their airspeed with increasing crosswind speed. Overall, bats modulated their airspeed in relation to wind speed at different wind directions in a manner predicted by a two-dimensional optimal movement model. We conclude that sophisticated behavioural mechanisms to minimize the cost of transport under various wind conditions have evolved in bats. The bats’ response to the wind is similar to that reported for migratory birds and insects, suggesting convergent evolution of flight behaviours in volant organisms.     

Sources and Levels of Ambient Ocean Sound near the Antarctic Peninsula

Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (Antarctic Peninsula region) from 2005 to 2009 to record ambient ocean sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the ocean soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapid disintegration also releases significant acoustic energy, equivalent to large-scale geophysical events. Overall ambient sound levels can be as much as ~10–20 dB higher in the open, deep ocean of the Scotia Sea compared to the relatively shallow Bransfield Strait. Noise levels become lowest during the austral winter, as sea-ice cover suppresses wind and wave noise. Ambient noise levels are highest during austral spring and summer, as surface noise, ice cracking and biological activity intensifies. Vocalizations of blue (Balaenoptera musculus) and fin (B. physalus) whales also dominate the long-term spectra records in the 15–28 and 89 Hz bands. Blue whale call energy is a maximum during austral summer-fall in the Drake Passage and Bransfield Strait when ambient noise levels are a maximum and sea-ice cover is a minimum. Fin whale vocalizations were also most common during austral summer-early fall months in both the Bransfield Strait and Scotia Sea. The hydrophone data overall do not show sustained anthropogenic sources (ships and airguns), likely due to low coastal traffic and the typically rough weather and sea conditions of the Southern Ocean.     

2012年盛夏多台风发生对褐飞虱迁飞动态的影响

【目的】台风能极大地改变褐飞虱Nilaparvata lugens(Sta1)的迁飞路径和落区分布,阐释连续登陆的台风对褐飞虱种群动态的影响,可为其异地预测提供科学依据。【方法】通过对2012年盛夏的台风"韦森特"、"苏拉"、"海葵"等影响时期的多站点灯诱数据和风场做轨迹分析,解析台风影响下褐飞虱迁飞动态的变化。【结果】2012年盛夏,多个台风在华南江南早稻黄熟收割和褐飞虱羽化迁出高峰期连续登陆我国,高空气流场和雨带分布发生了不利于褐飞虱北迁的变化。华南地区多盛行东北风或偏东风,即使在台风过境后有利北迁的风向影响时,持续强降水、风切变和下沉气流多发而不利北迁。西南季风受台风影响始终无法主导大气流场,北迁通道难以建立,而褐飞虱的第5次北迁进程受阻。【结论】2012年盛夏台风多发严重阻滞了褐飞虱的第5次北迁过程,大大减轻了长江中下游水稻主产区褐飞虱的危害程度。7月中下旬和8月上旬的风场条件和雨带位置是决定我国长江中下游稻区褐飞虱发生程度的重要预警指标。     

East Asian Monsoon Signals Reflected in Temperature and Precipitation Changes over the Past 300 Years in the Middle and Lower Reaches of the Yangtze River

Based on observational data and Asian monsoon intensity datasets from China, the relationships between the East Asian winter monsoon index and winter temperature, the East Asian summer monsoon index and Meiyu precipitation over the middle and lower reaches of the Yangtze River, were analyzed. We found that the monsoon signals were reflected in the temperature and Meiyu precipitation variations. Thus, we used the reconstructed Meiyu precipitation and winter temperature series for the past 300 years and detected the summer/winter monsoon intensity signals using multi-taper spectral estimation method and wavelet analysis. The main periodicities of Meiyu precipitation and winter temperature, such as interannual cycle with 2–7-year, interdecadal-centennial cycles with 30–40-year and 50–100-year, were found. The good relationships between the East Asian summer and winter monsoons suggested that they were in phase at 31-year cycle, while out of phase at 100-year cycle, but with 20-year phase difference. In addition, the winter monsoon intensity may be regulated by the North Atlantic Oscillation, the Arctic Oscillation and the Atlantic Multidecadal Oscillation, and the summer monsoon is closely related to the signal intensities of the Pacific Decadal Oscillation.