森林采伐限额制度存在的问题及建议

森林采伐限额是采伐消耗森林、林木蓄积的最大限量。实行森林采伐限额管理是《森林法》确定的一项重要法律制度,是控制森林资源过量消耗的核心措施和加强森林可持续经营的关键手段。本文阐述了森林采伐限额的概念,分析了当前采伐制度存在的一些问题,提出了改进措施及具体做法,以寻求最佳的森林采伐管理制度,保护好国家珍贵而有限的森林资源,达到科学经营的目的。     

基于能值-生态足迹修正模型的区域可持续发展研究——以江苏省南通市为例

在系统分析能值—生态足迹模型缺陷的基础上,通过增加人工投入指标,统一能值密度以及引入折能/折标系数对其进行了修正,并采用修正后的模型对江苏省南通市1996—2010年的可持续发展水平进行了测算。结果表明:(1)1996—2010年间南通市人均生态足迹由0.65hm2增长到0.90hm2,主要是由能源消费量的增加引起的;(2)同期南通市人均生态承载力由0.51hm2增长到0.81hm2,这主要是由农、畜产品产量提高和水电开发力度加大引起的,而通过劳务和资金投入提高承载力的空间很大;(3)1996—2010年南通市一直处于生态赤字状态,可持续性评价指数也都在0.5以上,区域发展处于不可持续状态。为进一步缩小生态承载力与生态足迹之间的差距,应采取以下措施:引导重点行业和企业节能降耗,大力发展新能源;加大农业科技投入,继续提高农产品产量;重视人力资源的投入,促使经济发展方式向技术密集型和资本密集型转变。     

Subcutaneous fatty acid composition of steers finished as weanlings or yearlings with and without growth promotants

Background: The current study evaluated the subcutaneous fatty acid(FA) composition of calf- and yearling-fed stee with or without growth promoting implants. Crossbred steers(n = 112; 267 ± 5.0 kg) of the same contemporary group were allocated to one of four production system and implant strategy based treatments in a completely randomized design with a 2 × 2 factorial arrangement of treatments.Results: There were no interactions(P 0.05) between production systems and growth promoting implants for the total and individual subcutaneous FA. Yearling as opposed to calf finishing reduced(P 0.05) subcutaneous proportions of C20:3n-6, trans(t)12-18:1, C14:0, several minor cis-monounsaturated FA(c-MUFA; c9-14:1, c11-16:1,c11-18:1, c12-18:1, c13-18:1, c9-20:1 and c11-20:1), and increased(P 0.05) subcutaneous proportions of t11c15-18:2,total and individual branched-chain FA. Subcutaneous fat from steers implanted with growth promotants had higher(P 0.05) proportions of total polyunsaturated FA(PUFA), total n-6 PUFA, C18:2n-6 and individual t-18:1isomers(t6 to t10) compared to non-implanted steers.Conclusions: Overall, current findings show that production systems and growth promotants led to only minor differences in subcutaneous FA composition of beef steers.     

Arabidopsis thaliana,an experimental host for tomato yellow leaf curl disease‐associated begomoviruses by agroinoculation and whitefly transmission

Tomato yellow leaf curl disease is one of the most devastating viral diseases affecting tomato crops worldwide. This disease is caused by several begomoviruses (genus Begomovirus, family Geminiviridae), such as Tomato yellow leaf curl virus (TYLCV), that are transmitted in nature by the whitefly vector Bemisia tabaci. An efficient control of this vector‐transmitted disease requires a thorough knowledge of the plant–virus–vector triple interaction. The possibility of using Arabidopsis thaliana as an experimental host would provide the opportunity to use a wide variety of genetic resources and tools to understand interactions that are not feasible in agronomically important hosts. In this study, it is demonstrated that isolates of two strains (Israel, IL and Mild, Mld) of TYLCV can replicate and systemically infect A. thaliana ecotype Columbia plants either by Agrobacterium tumefaciens‐mediated inoculation or through the natural vector Bemisia tabaci. The virus can also be acquired from A. thaliana‐infected plants by B. tabaci and transmitted to either A. thaliana or tomato plants. Therefore, A. thaliana is a suitable host for TYLCV–insect vector–plant host interaction studies. Interestingly, an isolate of the Spain (ES) strain of a related begomovirus, Tomato yellow leaf curl Sardinia virus (TYLCSV‐ES), is unable to infect this ecotype of A. thaliana efficiently. Using infectious chimeric viral clones between TYLCV‐Mld and TYLCSV‐ES, candidate viral factors involved in an efficient infection of A. thaliana were identified.     

Hydrogen radicals, nitrogen radicals, and the production of O3 in the upper troposphere

The concentrations of the hydrogen radicals OH and HO2 in the middle and upper troposphere were measured simultaneously with those of NO, O3, CO, H2O, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field. The data allow a direct examination of the processes that produce O3 in this region of the atmosphere. Comparison of the measured concentrations of OH and HO2 with calculations based on their production from water vapor, ozone, and methane demonstrate that these sources are insufficient to explain the observed radical concentrations in the upper troposphere. The photolysis of carbonyl and peroxide compounds transported to this region from the lower troposphere may provide the source of HOx required to sustain the measured abundances of these radical species. The mechanism by which NO affects the production of O3 is also illustrated by the measurements. In the upper tropospheric air masses sampled, the production rate for ozone (determined from the measured concentrations of HO2 and NO) is calculated to be about 1 part per billion by volume each day. This production rate is faster than previously thought and implies that anthropogenic activities that add NO to the upper troposphere, such as biomass burning and aviation, will lead to production of more O3 than expected.     

牛环形泰勒虫病二温式PCR诊断方法的建立及初步应用

为建立特异、敏感、快速的二温式PCR诊断方法,根据牛环形泰勒虫裂殖子表面抗原(tams1)基因,设计了一对特异性引物,扩增出大小为154bp基因片段,经克隆、测序分析,与已知基因序列的相似性为96%。用建立的牛环形泰勒虫病二温式PCR诊断方法,对从新疆牛环形泰勒虫病流行地区采集的50份全血样品进行诊断,阳性率为88%,而血涂片检出的阳性率只有58%。经试验验证,该方法具有特异性高、敏感性强、重复性和稳定性好等优点。表明本试验所建立的二温式PCR诊断方法可用于牛环形泰勒虫病的临床诊断、隐性感染检测和流行病学调查。     

畜牧兽医行政执法中证据收集应注意的问题

针对当前畜牧兽医行政执法中出现的突出问题,阐述了执法中证据收集应注意的问题并提出了改进措施。     

Inclusion body disease in two captive Australian pythons (Morelia spilota variegata and Morelia spilota spilota)

Two captive Australian pythons, one carpet and one diamond python, presented with signs of central nervous system dysfunction. The carpet python was agitated. Its head was tilting and it was incoordinated and had convulsions. It was treated with antibiotics and anthelmintics but was eventually euthanased after failing to respond to therapy. The diamond python had flaccid paralysis of the caudal half. It was not treated and became disoriented and died. Hepatocytes from both pythons contained irregular 2 to 10 m m eosinophilic intracytoplasmic inclusion bodies. The brain of the diamond python was not available for examination. Occasional neurones in the carpet python brain contained similar inclusion bodies and other changes suggestive of viral infection. The clinical signs and histopathological findings in both pythons were consistent with boid inclusion body disease.