The occurrence of phalaris staggers in sheep

Extract

Typical cases of the “staggers” syndrome associated with Phalaris tuberosa poisoning occurred at Invermay Research Station in October, 1954. It is being recorded because detailed records of pasture management and climatic conditions are available for the period when symptoms were seen, also the pasture composition of the Phalaris plot.     

Invertebrate drift densities in the Njoro and Kamweti Rivers in the Kenyan highlands that differ in the level of anthropogenic disturbances

Invertebrate drift is one of several fundamental ecological processes in streams. However, little is known about the dynamics of invertebrate drift in Kenyan streams. In this study, we assessed invertebrate drift in two rivers, i.e. Njoro and Kamweti, that differ in the level of anthropogenic disturbances, between February and March, 2016. The aim was to evaluate the effect of river sampling duration (5, 10, 15, 20 and 25 min) and sampling period (day or night) on invertebrate drift densities. The 5-minute sampling period resulted in significantly higher mean drift densities than the other time intervals in both rivers. The highest mean drift density (2.0 ± 0.9 individuals m^?3) was recorded at the Njoro River during the day, whereas the lowest drift density (0.3 ± 0.2 individuals m^?3) was recorded at the Kamweti River during the day. A strong nocturnal drift pattern was noted at the less disturbed river (Kamweti). The present results suggest that anthropogenic perturbations influence invertebrate drift densities, and sampling duration and sampling period are important factors to consider when sampling invertebrate drift.     

有机物料输入对关中土碳氮影响的后效作用

土壤有机碳氮是土壤肥力的关键因素,有机物料施用是提高土壤有机碳氮的有效措施。研究和比较了不同有机物料输入对土耕层（0—20 cm）土壤有机碳、全氮、可溶性有碳氮及0—200 cm剖面土壤硝态氮和含水量分布变化的后效作用。结果表明,停止施入有机物料两年后,与对照（CK）相比,秸秆与氮磷肥配施（SNP）和生物炭与氮磷肥配施（BNP）的表层（0—20 cm）土壤有机碳（SOC）分别提高了29.5%和29.8%（p<0.05）;氮磷肥（NP）、有机肥与氮磷肥配施（MNP）、秸秆与氮磷肥配施（SNP）和生物炭与氮磷肥配施（BNP）的表层土壤全氮含量较CK分别提高了22.0%,14.3%,24.2%和26.4%（p<0.05）。BNP处理的土壤可溶性有机碳（DOC）显著高于其他处理（p<0.05）,分别比CK,NP,MNP和SNP提高了23.4%,10.9%,21.3%,20.5%;所有施肥处理的土壤可溶性有机氮（DON）均显著高于CK（p<0.05）,分别提高了39.3%,29.3%,34.5%和52.3%。与CK相比,各施肥处理显著提高了表层土壤硝态氮含量（p<0.05）,增加了0—100 cm土层的硝态氮累积量。与NP处理相比,MNP和SNP显著提高了0—200 cm土层的硝态氮累积量（p<0.05）,而BNP则差异不显著。相比CK,施肥处理（NP,MNP,SNP,BNP）可显著提高0—20 cm土层的含水量,增加0—40 cm土层的储水量,且BNP处理显著高于SNP和MNP。总体而言,生物炭在提高和维持表层土壤肥力以及降低剖面硝态氮淋溶风险等方面的后效作用显著优于秸秆和有机肥,是陕西关中地区旱地土上一种较好的有机物料施用方式。     

长期水耕植稻对水稻土耕层质地的影响

为了解长期水耕植稻对南方地区水田表土层颗粒组成的影响,以浙江省为研究区,采用历史资料分析、典型样区调查及定点观察相结合的方法,研究水稻土耕作层(包括犁底层)与心土层间黏粒含量的差异,分析植稻时间对水稻土不同土层颗粒组成的影响,比较植稻期间稻田排水中泥砂物质的颗粒组成与对应土壤间的差异,探讨了长期植稻对水稻土剖面质地分异的影响。对浙江省456个代表性剖面统计,与水稻土心土层比较,耕作层和犁底层黏粒含量平均下降了14%和10%。对植稻不同时间的浅海沉积物(从10～20年至80年)、第四纪红土(从5～20年至70年)和玄武岩风化物(从5～20年至35～70年)发育的水稻土比较发现,随植稻时间的增加,耕作层和犁底层土壤砂粒含量呈现增加趋势,黏粒含量明显下降,耕作层、犁底层与心土层黏粒含量的比值逐渐下降。农田排水中泥砂物质的黏粒和粉砂含量高于对应农田土壤,而砂粒含量则低于相应的土壤。分析认为,长期水耕植稻可导致耕作层土壤砂化(即砂粒含量增加,黏粒含量下降),其原因除与水耕过程中黏粒淋淀外,排水中黏粒和粉砂细颗粒的选择性流失对耕作层砂化也有较大的贡献。     

人类活动对大亚湾海域鱼类群落多样性及其演替的影响

根据2015—2016年间对大亚湾海域进行的4个航次底拖网调查数据,分析了大亚湾鱼类群落的种类组成和多样性特征。结果表明,调查共采集到鱼类131种,隶属14目、53科、84属。其中以鲈形目(Perciformes)占绝对优势(54.20%),其次是鳗鲡目(Agunilliformes)和鲽形目(Pleuronectiformes),均占9.92%。种类数具明显季节变化,以夏季最高,69种;春季最低,32种。鱼类群落优势种组成主要以二长棘犁齿鲷(Evynnis cardinalis)、李氏(Callionymus richardsoni)、斑(Clupanodon punctatus)、竹荚鱼(Trachurus japonicus)、黄鳍马面鲀(Thamnaconus hypargyreus)、短吻鲾(Leiognathus brevirostris)和细条天竺鲷(Apogon lineatus)等小型鱼类为主。多样性分析显示,鱼类物种多样性存在明显的季节差异和空间差异。季节变化上,多样性指数(H')季节变化范围为1.516~1.998,以冬季最高,秋季最低;均匀度指数(J')季节变化范围为0.494~0.869,以冬季最高,夏季最低;丰富度指数(D')季节变化范围为2.230~3.777,以夏季最高,秋季最低。典范对应分析表明,温度、盐度和水深是影响大亚湾海域鱼类群落结构的主要环境因子。空间分布上,海湾中部海域鱼类多样性水平高于沿岸海域。与历史资料相比,由于人类活动对大亚湾生态系统的干扰,鱼类群落结构发生了较大变化,优势种组成更替明显,多样性水平降低,鱼类群落结构趋向简单化。     

Air pollution affects food security in China: taking ozone as an example

Air pollution is becoming an increasingly important environmental concern due to its visible negative impact on human health. However, air pollution also affects agricultural crops or food security directly or indirectly, which has not so far received sufficient attention. In this overview, we take ozone (O ₃ ) as an example to analyze the principles and extent of the impact of air pollution on food security in China based on a review of the literature. Current O ₃ pollution shows a clear negative impact on food security, causing around a 10% yield decrease for major cereal crops according to a large number of field studies around the world. The mean yield decrease of winter wheat is predicted to be up to 20% in China, based on the projection of future ground-level O ₃ concentration in 2020, if no pollution control measures are implemented. Strict mitigation of NO _x and VOC _s (two major precursors of O ₃ ) emissions is crucial for reducing the negative impacts of ground-level O ₃ on food security. Breeding new crop cultivars with tolerance to high ground-level O ₃ should receive serious consideration in future research programs. In addition, integrated soil-crop system management will be an important option to mitigate the negative effects of elevated ground-level O ₃ on cereal crop production and food quality.     

Human induced dryland degradation in Ordos Plateau,China, revealed by multilevel statistical modeling of normalized difference vegetation index and rainfall time-series

Land degradation causes serious environmental problems in many regions of the world,and although it can be effectively assessed and monitored using a time series of rainfall and a normalized difference vegetation index(NDVI)from remotely-sensed imagery,dividing human-induced land degradation from vegetation dynamics due to climate change is not a trivial task.This paper presented a multilevel statistical modeling of the NDVI-rainfall relationship to detect human-induced land degradation at local and landscape scales in the Ordos Plateau of Inner Mongolia,China,and recognized that anthropogenic activities result in either positive(land restoration and re-vegetation)or negative(degradation)trends.Linear regressions were used to assess the accuracy of the multilevel statistical model.The results show that:(1)land restoration was the dominant process in the Ordos Plateau between 1998 and 2012;(2)the effect of the statistical removal of precipitation revealed areas of human-induced land degradation and improvement,the latter reflecting successful restoration projects and changes in land management in many parts of the Ordos;(3)compared to a simple linear regression,multilevel statistical modeling could be used to analyze the relationship between the NDVI and rainfall and improve the accuracy of detecting the effect of human activities.Additional factors should be included when analyzing the NDVI-rainfall relationship and detecting human-induced loss of vegetation cover in drylands to improve the accuracy of the approach and eliminate some observed non-significant residual trends.     

草地植物多样性对人类干扰的多尺度响应

人类干扰是草地生态系统植物多样性变化的主要导因之一。植物多样性的形成依赖于一定空间和时间尺度上的生态系统结构与过程,只有在特定的时空尺度上才能充分表达其主导作用与效应。植物多样性的尺度特征和人类干扰的大尺度效应决定了草地植物多样性保护的复杂性和艰巨性。论述了不同尺度的草地植物多样性对放牧、旅游、刈割、施肥及开垦等各种人类干扰响应的方式、过程与生态后果,明确了尺度问题在研究中的重要作用,探讨了草地植物多样性在人类干扰下的变化导因与响应机制,以期为草地植物多样性的保护、合理利用及草地生态系统的可持续发展提供科学依据。     

The implications for aquaculture practice of epigenomic programming of components of the endocrine system of teleostean embryos: lessons learned from mammalian studies

Epigenetics is the study of changes in gene expression patterns that occur without any modification of the underlying nucleotide sequence of the DNA. Modifications of the so‐called epigenome include complex transient or permanent chemical changes of the DNA or histone proteins resulting in the suppression or enhancement of gene expression, together with an array of post‐translational events that modify the translational products. Epigenomic programming (EP) of the genome is an essential component of embryonic development in animals from the totipotent fertilized egg to the pluripotent stem cells, stem cell differentiation and final tissue and organ formation. Many of these EP processes are influenced transiently and some permanently by environmental influences. In eutherian mammals, environmentally related EP of embryos is linked to permanent changes in the phenotype of the progeny, some of which have been associated with adult onset metabolic disorders. Moreover, because some of the epigenetic remodelling occurs in both the soma and germ line, the resultant phenotypic characteristics (some of which are linked to disease states) may be heritable. Although far less is known about the effects of environmentally linked EP on the ontogeny of fishes, the available information suggests that the EP processes are similar amongst all vertebrates, and there are clear parallels between fish and mammals that are discussed in this paper. Our perspective takes the well‐established findings in mammals and uses them to proactively extrapolate to the as yet under‐recognized implications of EP for fish biology and for fish production in intensive aquaculture.     

人为能量投入对农田生态系统净初级生产力的影响——以鲁西南地区为例

为了确定影响农田生态系统固碳能力的影响因子,在收集2000—2006年鲁西南地区农业生产统计数据的基础上,分析了该地区农田人为能量投入现状,并利用回归和逐步回归的方法研究了鲁西南地区人为能量投入对农田生态系统净初级生产力(NPP)的影响。结果表明：鲁西南地区农田人为能量投入中农膜的投入逐年增加,由2000年的14.6 kg/hm2增长到2006年的20.5 kg/hm2;化肥投入相对稳定(1200~1300 kg/hm2),但总量仍增加;农药的投入呈先增加后降低的趋势,2004年达到最高(11.03 kg/hm2);排灌机械、农用车辆的投入呈增长趋势,而单位面积劳动力的投入不断下降,2006年与2000年相比约减少0.65人/hm2。该地区农田生态系统NPP存在着东高西低的空间分布格局,历年均以东部（枣庄、济宁）高,平均NPP分别为616 g C/(m2?a)和588 g C/(m2?a),西部（菏泽）低,仅有448 g C/(m2?a);年际间呈现一定的波动性,但整体呈上升趋势。该地区农田NPP主要受人为能量投入的影响而与温度和降水的关系不大。单位面积化肥使用量、单位面积农膜使用量和农田灌溉比例在逐步回归模型中可以解释本区农田NPP方差的74.6%。因此,化肥、农膜、有效灌溉比等人为能量投入是影响该地区农田NPP提升的主要因素。