The measurement of chronic disturbance and its effects on the threatened cactus Mammillaria pectinifera

Measuring how anthropogenic disturbance affects biological systems is crucial for conservation and management. However, it is often difficult to quantify disturbance when it occurs in a slow, long-lasting - or chronic - fashion. Because various human activities influence gradually an area, chronic disturbance must be measured on a continuous scale that accounts for different sources of disturbance. Here we propose a method to develop multimetric indices for chronic disturbance. The approach is exemplified by considering the effects of disturbance on the threatened cactus Mammillaria pectinifera. Fourteen indicators of three agents of disturbance (human activities, livestock raising and land degradation) were measured in 10 populations of M. pectinifera, and summarised through principal components analysis (PCA). An index for each agent was also developed. M. pectinifera achieved maximum density at intermediate values of the first PCA axis, which was related to disturbance intensity. Assessing only both extremes of the disturbance gradient, where density is low, would erroneously suggest that disturbance has no effect on this plant. The different disturbance agents act synergistically on M. pectinifera, and their combined effects are detrimental. Land degradation reduces plant density, while livestock enhances it. However, overgrazing promotes degradation, so maintaining appropriate livestock levels is critical for management. Our method allowed us to identify which agents have more impact on threatened species, and sets the basis to manage disturbance agents in a way compatible with conservation. The method proposed here can be easily modified for its use in other environments and to account for different forms of anthropogenic disturbance.     

Determination of biological stability in compost: A comparison of methodologies

Biological [dynamic respiration index (DRI); chemical humification indexes: humification index (HI), degree of humification (DH) and humification rate (HR); and thermoanalytical (thermostability index, R₁ and a labile fraction)] indexes were used to assess compost stability of 15 end products. By use of these three techniques independent assessment of compost stability was made possible. Evidence of unstable materials was found where labile, easily biodegradable, and non-humified organic fractions were present. The DRI was used as a reference index for biological stability, and no significant correlation was observed between DRI and the humification indices (HI, DH, HR) and the thermogravimetry index (R₁). On the other hand, significant correlation was observed for DRI vs. non-humified carbon (NHC), which was determined using the chemical method and the labile fraction determined by thermogravimetry, as well as for NHC vs. “labile fraction”. These fractions represent labile, easily biodegradable, and non-humified organic matter. Significant correlations were also observed between the three above mentioned measurements and TEC, suggesting that this fraction is mainly formed of the easily degradable organic fraction. These results suggest that the integrated use of biological, chemical, and thermoanalytical methods could represent a useful tool in differentiating stabilized composts from non-stabilized ones, and it could provide more reliable information for both managerial and sanitary health aspects involved in good agricultural practice.     

基于车载式冠层光谱传感器的玉米拔节期叶绿素含量诊断

CropspecTM是一种基于735 nm 和808 nm的车载式主动作物冠层光谱传感器,能够快速、无损地检测作物氮素营养状态。为了评价其检测精度,针对农大8号和京农科等2种玉米作物品种,使用该检测系统在拔节期采集作物冠层在808nm和735nm波段处的反射率。然后组合计算了DVI735, NDVI735, PVI735和 RDV735 等常规的植被指数,并基于RVI735构造了一种新的植被指数MRVI735。通过分析各植被指数与叶绿素含量指标SPAD值之间的相关关系得出 :对于农大8号,MRVI735、NDVI735和RVI735与叶绿素含量指标的相关性较好,相关系数分别是:-0.7482、-0.6763和-0.6786,达到强相关水平。对于京农科,NDVI735、MRVI735和RVI735与叶绿素含量指标的相关性较好,相关系数分别是:0.7270、0.7252和0.7245,达到强相关水平。对于2个玉米品种,都分别选取了相关系数最好的一个和两个植被指数为参数,分别建立了一元线性回归模型和二元线性回归模型。农大8号的一元模型和二元模型的R2     

Species presence in fragmented landscapes: modelling of species requirements at the national level

The fragmentation of ancient woodland has been identified as a cause of decline in biodiversity in the UK. Current policy advocates the targeting of resources to mitigate its effects. In this study a number of patch and landscape scale measures of ancient woodland distribution were derived from national data sets. These measures were translated into independent variables representing patterns of woodland cover using principal component analysis (PCA). Key species were selected according to differing sensitivities to fragmentation of ancient woodland. Logistic regression models of species distributions were constructed.A range of bird and mammal distributions were found to be correlated to landscape scale measures of fragment distribution, in contrast to butterfly and plant species, which exhibited a stronger correlation to patch-scale measures. The national distribution of a range of woodland species is predicted. New information is presented on the landscape requirements of woodland species, particularly those that enable them to persist in fragmented woodland landscapes. The different scales at which species show a sensitivity to fragment distribution are discussed. The results confirm the association between species and different aspects of the structure of the wooded landscape, and provide information of value in targeting national conservation expenditure in England.     

Different approaches to evaluating soil quality using biochemical properties

Soil biochemical properties are indicators of soil quality, but there is still no consensus as to how they should be used. We review the trends in their use over the last decade. Generally, biochemical properties related to the biocycles of the elements (C, N, P and S) are used to diagnose soil quality. These properties include both general biochemical parameters (i.e. microbial biomass C, dehydrogenase activity and N mineralization potential) and specific biochemical parameters (i.e. the activity of hydrolytic enzymes, such as phosphatase, urease and β-glucosidase). Biochemical properties can be used both individually, as simple indices, or in combination using complex equations derived from mathematical combinations or the application of statistical programs. The results described in the literature for both are contradictory and question the validity of the use of biochemical properties as quality indicators. Complex expressions, in which different properties are combined, are thought to be highly suitable for estimating soil quality, although their use is limited to the area and situation in which they have been described. Generally, the greatest problems posed by the use of biochemical properties as soil quality indicators include the lack of reference values, the contradictory behaviour shown by these properties when a soil is degraded, and the regional variations in expression levels. Most of these problems are derived from the scarce information available on the biochemical properties of soil. For this reason, obtaining soil quality indicators of general use will require a coordinated effort from the international scientific community to standardise the analytical methods and to compile databases of biochemical properties from soils under diverse geographic conditions and with different uses and management.     

河北省土壤水资源分区及评价方法

土壤水资源分区是土壤水资源评价的基础，河北省地形地貌复杂、植被种类繁多，而且土壤水由于其赋存、运移和土壤质地、土层结构息息相关，所以需根据土壤的特性对河北省土壤水资源进行分区。在河北省土壤水资源资料分析的基础上，对河北省土壤水资源选取了地形地貌、干旱指数、土壤质地及植被条件4个评价指标，并采用权值因子判断表法来确定指标的权重，应用模糊聚类方法对河北省土壤水资源进行了分区，将河北省土壤水资源分为8区，并进行了分区研究，取得了较好的结果，其结果有利于河北省土壤水资源的研究。     

高等植物亚硫酸盐氧化酶研究进展

亚硫酸盐氧化酶(sulfite oxidase,SO)作为钼酶家族的第4个成员,参与生物体内硫代谢等重要的生理和生化过程。笔者对高等植物亚硫酸盐氧化酶的结构特征、生化特性及生物学功能等方面的最新研究进展作一综述,并展望了SO在提高植物抗环境污染(SO2、酸雨等)方面的应用潜力。     

两种山羊及杂交代血液生化遗传标记研究(Ⅰ)

用聚丙烯酰胺垂直平板电泳法，研究安哥拉山羊、山谷型藏山羊及杂种Ｆ１、Ｆ２血液中Ｈｂ、Ａｌｂ、Ｔｆ、ＡＫＰ、ＥＳ、ＬＤＨ、Ａｍ等基因座表明，血液Ｈｂ、Ａｌｂ、ＬＤＨ、Ａｍ呈单态；血液Ｔｆ、ＡＫＰ、ＥＳ等基因座呈多态。Ｔｆ基因座有三种基因型（ＡＡ、ＡＢ、ＢＢ）由Ａ基因和Ｂ基因控制。ＡＫＰ有两种基因型（ＡＫＰＦ、ＡＫＰＯ）。ＥＳ酶带类型复杂，可分为三区：ＥＳⅠ呈红色、ＥＳⅡ呈褐色、ＥＳⅢ呈紫褐色。运用血液Ｈｂ、Ｔｆ、ＡＫＰ、Ａｌｂ、Ａｍ的基因频率计算基因杂合度表明，安哥拉山羊的杂合度最小，Ｆ１代的杂合度最大。分析群体间遗传相似系数与级进杂交的变化一致；分析基因型分布差异表明亲本品种差异最大，安哥拉山羊与Ｆ１、Ｆ２间，Ｆ１和Ｆ２间差异较小。     

Effect of Chinese Herb Additive on Blood Biochemical Indices and Production Performance in Transition Dairy Cows

The objective of the experiment was to investigate the effect of Chinese herb additive on production performance and blood biochemical indices in transition dairy cows.Thirty six Holstein dairy cows were randomly assigned to three treatments,supplemented with 0,150 and 300 g/d Chinese herb additive,respectively.Experimental duration was 7 weeks and the first week was the preliminary period.After delivery,feed,blood and milk samples were collected once a week for the measurement of dry matter intake,blood biochemical indexes and milk components.The results showed that cows fed 150 and 300 g/d Chinese herb additive tended to increase milk production (5.1% and 10.6% respectively) compared to control group,but the difference was not significant (P<0.05).Meanwhile,the somatic cell count in milk significantly decreased (P<0.05),which decreased by 62.7% and 76.6%,respectively.Feeding Chinese herb additive had no significant effect on dry matter intake and other milk composition (P>0.05).Compared to control group,cows received Chinese herb additive significantly decreased the content of serum NEFA (P<0.05),which decreased by 29.0% and 35.1%,respectively.There was no significant difference on other indexes in serum (P>0.05).The results showed that dietary supplementation with 300 g/d Chinese herb additive had a good effect for transition dairy cows,which could significantly reduce the somatic cell count in milk and the content of NEFA in blood,and would improve the health status of dairy cows,and the postpartum production performance of dairy cows.     

黄曲霉毒素对猪生长性能及免疫和抗氧化指标的影响

选用60头体质量28 kg左右的“杜长大”三元杂交猪,随机分为2组,每组3个重复,每个重复10头猪（公母各半）,分别饲喂基础日粮（C组）、基础日粮添加0.1 mg/kg黄曲霉毒素（AF组）,试验期90 d。饲养试验结束时,对猪的生长性能、免疫指标和抗氧化指标进行分析。结果表明：黄曲霉素显著影响试验猪的生长性能,日增重降低12.90%（P〈0.01）,料重比提高7.54%（P〈0.01）,同时显著降低试验猪的免疫功能和抗氧化能力。提示：长期饲喂0.1 mg/kg黄曲霉素可诱发猪黄曲霉毒素慢性中毒。