以杨树抗虫品种为主综合防治光肩星天牛技术的研究

以杨树抗虫品种为主综合防治光肩星天牛技术的研究＊秦锡祥高瑞桐李吉震曹桂洪陈维培关键词杨树抗虫品种、综合防治、光肩星天牛光肩星天牛［Ａｎｏｐｌｏｐｈｏｒａｇｌａｂｒｉｐｅｎｎｉｓ（Ｍｏｔｓｃｈ）］是杨树（Ｐｏｐｕｌｕｓｓｐｐ．）重要的蛀干害虫，造成木材...     

我国林下经济集约经营现状及建议

目前, 以林下种植、林下养殖、林下产品加工等为主要内容的林下经济在我国各地已经有了很大发展.文中总结林下经济的产生与发展过程, 分析林下经济集约经营现状, 从理论层面剖析其经济学和管理学价值; 在此基础上讨论林下经济集约经营过程中存在的问题; 最后从发展理念、政府服务、典型带动、市场引导等方面提出推进林下经济集约经营发展的建议, 以期更好地引导和规范林下经济的发展.     

紫茎泽兰叶片气体交换的气孔调节特性:对其入侵能力的意义

紫茎泽兰是一个典型的外来入侵植物.利用便携式光合测定系统,对分布于四川省凉山州德昌市郊(27°28′36"N,102°12′28″E)的紫茎泽兰的气体交换特性进行测定,并与本地8个伴生种和其他12个分布于我国不同地区和日本的入侵种和本地种进行比较.目的是探讨气孔调节在日变化过程和长期干旱与湿润生境上的差异及其对紫茎泽兰入侵能力的影响.研究发现紫茎泽兰光合午休现象明显,气孔调节和非气孔调节共同控制了紫茎泽兰的光合日进程模式,而以气孔调节最为重要.非气孔调节主要是通过羧化效率的降低,从而影响表观量子效率或其他光合过程来实现的,而气孔调节主要是通过降低胞间CO2浓度,提高气孔限制值来实现的,这与其他种的差异不大.经过长期的野外不同湿度环境适应后,气孔调节出现了一定的弹性变化.在气孔导度相差不大的情况下,土壤有机质、土壤pH值和土壤有效氮含量差异不明显,湿生生境的光合速率和蒸腾速率显著高于干生生境,并导致了叶片含氮量显著提高.气孔在调节紫茎泽兰水分利用效率方面有别于所测定的其他20种植物,在湿生生境下随气孔导度下降,水分利用效率下降,而在干生生境下则显著升高.因此,紫茎泽兰同时兼有"省水"植物和"费水"植物的双重特点,这一灵活水分利用特点保证了它在不利环境中的生存和有利环境中的扩展,对于其在侵入区的生长发育有一定的意义.     

Competitive interactions in Ginkgo and crop species mixed agroforestry systems in Jiangsu,China

Intercropping Ginkgo and crop species in southern China is receiving increasing attention because it offers potential advantages for resource utilization, higher economic income to farmers and increased sustainability in crop production, We carried out a 2-year field intercropping system composed of Ginkgo with wheat, broad bean, and rapeseed, respectively, to determine the competitive interactions between the different species, and productivity and the economic yield of each intercropping system. The density of Ginkgo and crop species was varied systematically in a two-way density matrix composed of three monoculture densities and nine intercropping of all possible pairwise combinations of monoculture densities. Intercropping systems were assessed on the basis of several intercropping indices such as land equivalent ratio, relative crowding coefficient, relative competition intensity and vector competition analysis. The results showed that the combined biomass production of the component crop species was significantly greater in the Ginkgo/crop mixtures than in monocultures crops (Ginkgo, broad bean, wheat, and rapeseed). Ginkgo: rapeseed ratio 24:12, Ginkgo: bread bean ratio 24:5, and Ginkgo: wheat ratio 24:200 had the best total biomass production. Ginkgo: rapeseed (and broad bean) ratio 24:5 and Ginkgo: wheat ratio 24:200 in respective Ginkgo/crop mixtures had the maximum economic yield. Vector competition analysis showed that Ginkgo/rapeseed mixture exhibited an antagonistic interaction type and therefore is not suitable for intercropping. Ginkgo/broad bean mixture demonstrated the most beneficial effects among the three intercropping systems.     

Relationship between photosynthesis and leaf nitrogen concentration in ambient and elevated [CO2] in white birch seedlings

To study the effects of elevated CO2 concentration ([CO2]) on relationships between nitrogen (N) nutrition and foliar gas exchange parameters, white birch (Betula papyrifera Marsh.) seedlings were exposed to one of five N-supply regimes (10, 80, 150, 220, 290 mg N l(-1)) in either ambient [CO2] (360 micromol mol(-1)) or elevated [CO2] (720 micromol mol(-1)) in environment-controlled greenhouses. Foliar gas exchange and chlorophyll fluorescence were measured after 60 and 80 days of treatment. Photosynthesis showed a substantial down-regulation (up to 57%) in response to elevated [CO2] and the magnitude of the down-regulation generally decreased exponentially with increasing leaf N concentration. When measured at the growth [CO2], elevated [CO2] increased the overall rate of photosynthesis (P(n)) and instantaneous water-use efficiency (IWUE) by up to 69 and 236%, respectively, but decreased transpiration (E) and stomatal conductance (g(s)) in all N treatments. However, the degree of stimulation of photosynthesis by elevated [CO2] decreased as photosynthetic down-regulation increased from 60 days to 80 days of treatment. Elevated [CO2] significantly increased total photosynthetic electron transport in all N treatments at 60 days of treatment, but the effect was insignificant after 80 days of treatment. Both P(n) and IWUE generally increased with increasing leaf N concentration except at very high leaf N concentrations, where both P(n) and IWUE declined. The relationships of P(n) and IWUE with leaf N concentration were modeled with both a linear regression and a second-order polynomial function. Elevated [CO2] significantly and substantially increased the slope of the linear regression for IWUE, but had no significant effect on the slope for P(n). The optimal leaf N concentration for P(n) and IWUE derived from the polynomial function did not differ between the CO2 treatments when leaf N was expressed on a leaf area basis. However, the mass-based optimal leaf N concentration for P(n) was much lower in seedlings in elevated [CO2] than in ambient [CO2] (31.88 versus 37.00 mg g(-1)). Elevated [CO2] generally decreased mass-based leaf N concentration but had no significant effect on area-based leaf N concentration; however, maximum N concentration per unit leaf area was greater in elevated [CO2] than in ambient [CO2] (1.913 versus 1.547 g N m(-2)).     

欧盟碳排放权交易体系现状及启示

碳排放权交易是指建立合法的温室气体排放权和总量控制目标并进行排放权买卖。文中通过分析欧盟碳排放权交易体系及我国碳排放权交易市场现状认为, 我国目前尚未具备建立强制性碳排放权交易市场的经济基础, 但可以先依托CDM一级市场培育自愿抵消市场和CDM二级市场并时刻关注国际碳排放权政策变动, 避免政策风险。     

金钟藤在海南的危害与防治

对国内原产地的金钟藤进行初步调查,发现该种在海南岛分布广泛,并对该岛中部山区的中低海拔次生林和人工残次林造成严重危害;而在云南、广西等省区虽有分布,但危害较轻。根据对金钟藤生物生态学特性的分析,结合其在新旧分布地的现状,认为该种为典型的生态危害种,具有很强的潜在入侵能力,对其防治应以综合防治为主。     

地肤提取物对山楂叶螨体内几种酶活性的影响

采用生化方法测定地肤三氯甲烷提取物对山楂叶螨体内谷胱甘肽-S-转移酶、羧酸酯酶、单胺氧化酶、Ca2 -ATP酶活性的影响.结果表明:地肤提取物处理山楂叶螨后,螨体内谷胱甘肽-S-转移酶、羧酸酯酶等解毒酶活性被激活,谷胱甘肽-S-转移酶、羧酸酯酶都是昆虫体内重要的代谢解毒酶系,它们参与了昆虫对内源或异源有毒物质的代谢解毒,特别是对杀虫剂的解毒,这表明地肤提取物中存在对山楂叶螨有毒的物质,从而引起了螨体的解毒作用,来维持正常的生理功能.而单胺氧化酶、Ca2 -ATP酶的活力受到一定程度的抑制.Ca2 -ATP酶的被抑制,可能会破坏细胞内外Ca2 的平衡,影响神经细胞的兴奋和传导,引起神经传递的阻断;单胺氧化酶被抑制,使螨体内神经胺积累,也会造成神经传递的阻断,从而导致螨体的死亡.以上结果表明地肤作为新型植物源农药具有良好的开发前景.     

基于结构转换视角的中国重点国有林区经济转型发展路径分析

在我国全面停伐背景下, 实现国有林区经济社会转型迫在眉睫。文中测算、对比和评价2003—2014年全国及重点国有林区产业结构转换速度和方向, 以期掌握重点国有林区近年产业结构变动的基本特征, 得到以下结论:1)重点国有林区各森工林区产业结构转换速度普遍较慢, 同一林区不同产业的增速差异化不显著; 2)重点国有林区产业结构转换方向总体合理, 三次产业比重变动趋势有助于实现林区产业效率均衡与结构稳定; 3)重点国有林区产业结构转换能力整体低于全国水平。根据研究结论, 从巩固非林替代产业、培育主导产业、因地制宜进行产业结构与布局调整、注重制度配套以及深化体制改革等方面提出支撑重点国有林区产业结构调整与经济转型发展的可行路径。