入侵植物加拿大一枝黄花的高光谱特性研究

加拿大一枝黄花（Solidago canadensis L.）原产北美,是一种世界性的入侵性外来杂草,目前正在我国东、南部地区迅速扩散,严重威胁生态系统生物多样性和农林业生产。该研究利用美国ASD公司生产的ASD FieldSpec ProFRTM光谱辐射仪,测定了杭州湾地区加拿大一枝黄花的冠层表观反射率光谱,并分析了其高光谱反射率特征。结果显示：黄光区域内基于位置和面积的高光谱特征参量Dy、λy和SDy具有较小的变异系数,可以作为识别加拿大一枝黄花的特征参量。研究表明：利用高光谱遥感技术来识别外来入侵杂草是可行的。     

Comparison of feed intake,body weight gain,enteric methane emission and relative abundance of rumen microbes in steers fed sainfoin and lucerne silages under western Canadian conditions

Beef cattle are major contributors of enteric methane (CH₄) emissions in Canada. Feeding forages containing condensed tannins (CT) has been suggested as a means of reducing enteric CH₄ emissions and improving production efficiency. Sainfoin (Onobrychis viciifolia) is one of the CT‐containing legumes, which has also been recognized to have several additional beneficial properties. This study compared sainfoin silage (SS) and lucerne (Medicago sativa) silage (LS) with respect to animal performance, enteric CH₄ production, abundance of selected rumen microbes and selected serum parameters in yearling steers during a Canadian winter. Sainfoin silage in our study contained approximately 12 g CT kg^?1 dry matter (DM), a level which did not adversely affect silage palatability as steers fed SS experienced higher DM intake. However, animals fed LS and SS had similar body weight gain over the course of the trial. Feeding SS resulted in lower blood urea nitrogen concentrations and relative abundance of methanogenic archaea in rumen fluid. Yet, microbial population shifts fell short of exerting significant influence on enteric CH₄ emissions. This study suggests that under western Canadian growing and animal‐rearing conditions, sainfoin is not yet competitive with lucerne forage with respect to enteric CH₄ emissions or animal productivity warranting further research and development.     

Approaches for controlling sea lice infestation in global salmon farming: What is applicable in Canadian aquaculture industry

ABSTRACT

This article describes the sea lice control methods that are currently applicable to salmon farming in Canada. Three commercial chemical products are approved for use against sea lice in Canada: Slice®, Interox® Paramove® 50, and Calicide®. Physical control methods include photoperiod and cage-depth manipulations, desiccation of farm equipment, and the use of electric fences. Biological control measures include the polyculture of salmon with wrasse or mussel. Nutraceuticals and immunostimulants shown to reduce sea lice infestations in salmon include unmethylated DNA, yeast fermentation extract-Brewer’s yeast compound, AllBrew and NuPro, MacroGard®, and Optimûn®. Salmon farmers are recommended to use site-specific integrated approaches, by properly adapting a combination of chemical, physical, biological, and nutritional measures to the environmental and financial characteristics of their farm. In the future, development of vaccines against sea lice and of salmon lines resistant to sea lice will play a pivotal role in fighting against this parasite.     

加拿大森林资源环境库兹涅茨曲线验证——基于林木生长周期的视角

利用加拿大1990—2010年林产品产量数据, 采用环境库兹涅茨曲线模型, 考察加拿大经济增长与森林资源采伐量之间的关系。与以往研究不同的是, 在回归模型中加入了代表林木生长周期的时间序列变量, 以探讨林木生长周期对森林资源采伐量的影响。结果显示, 加拿大森林资源采伐量与经济增长存在倒U型曲线关系, 且林木生长周期对曲线形状的影响显著。从研究结果得到的政策启示是, 在设置森林采伐限额时应注意林木的生长周期, 在林木初生长期应降低采伐限额来保护幼树, 从而为采伐迹地天然更新提供充足的种源和条件。     

加拿大森林可持续经营研究进展及其对中国的启示

加拿大是蒙特利尔进程倡导者、成员国和进程秘书处所在国,蒙特利尔进程是关于温带及北方森林保护与可持续经营标准与指标的多边联合行动,中国是蒙特利尔进程的成员国,同时也是以温带及北方森林为主体的国家。森林可持续经营是1992年世界环境与发展大会后为解决全球环境与发展问题而出现的新的研究方向,也是联合国森林论坛的议题,加拿大在该领域一直处于领先位置,因此研究加拿大在森林可持续经营方面主要开展的工作及所取得的进展,分析他们的工作方法和经验,对我国开展该领域的工作具有重要的参考价值     

Change in historic fire disturbance in a Garry oak (Quercus garryana) meadow and Douglas-fir (Pseudotsuga menziesii) mosaic,University of Victoria,British Columbia,Canada: A possible link with First Nations and Europeans

We investigated late Holocene vegetation and fire changes on southeast Vancouver Island, British Columbia, through high-resolution analysis of pollen, spores and charcoal contained within a forest soil. Located in the Mystic Vale Endowment lands, University of Victoria campus, the site occurs adjacent to Garry oak (Quercus garryana) meadows within a Douglas-fir (Pseudotsuga menziesii) forest regionally influenced by First Nations burning. The age of the sequence is estimated from the occurrence of non-native plantain (Plantago spp.) pollen, between the early 19th century and the present. Prior to the 1850s, the Mystic Vale supported a Douglas-fir forest with a sword fern (Polystichum munitum) understory. Low-intensity fires may have burned either at or near the site, but did not destroy the stand. From the time of European settlement (ca. 1850s to 1872) to the early 20th century, Douglas-fir forests with a sword fern understory persisted but with more openings than in the past. Adjacent forests were cleared leading to successional stands of red alder (Alnus rubra). The site may have supported more grasses near or after 1872 because of adjacent cultivation and the introduction of livestock. Local establishment of Garry oaks at the margin of a field adjacent to the deposition site may have occurred at this time. The strong charcoal signal may be attributable to clearing and local fires of European settlers. Exotic weedy species such as plantain arrived during this time. From about the mid 20th century to the present a closed canopy Douglas-fir forest returned. Pre-European charcoal concentrations were significantly greater than modern-day charcoal concentrations. Peak charcoal concentrations coincided with the onset of European settlement in the area, a period in which land-clearing is thought to have been aided by the use of fire. This study suggests that the observed changes in charcoal concentrations in pre- and post-European contact time may be linked with a switch from aboriginal to European ignition sources. The study provides a historical impetus to consider partially restoring parts of southeast Vancouver Island by re-introducing fire via the application of controlled burns.     

加拿大林产工业的最新进展

加拿大是世界林产品生产大国和贸易大国。文中概述了加拿大近几年锯材、人造板、纸浆、纸和纸板等主要林产品的生产情况, 以及2004年的林产品出口情况。在此基础上, 归纳出加拿大林产工业的6个特点。