南方红豆杉种子萌发生物学研究

对南方红豆杉种子的萌发生物学特性进行研究,主要结果表明：（１）种子在自然条件下有很深的休眠特性,但种皮透性不是休眠的原因;（２）对鹇种子进行“暖温（２５℃）层积－低温（５℃）层积”,以“３６周－１２周”的模式效果最好,能促进胚纵向生长和打破种子休眠,发芽率达６４．０％～８２．２％。     

对新疆杨扦插生根机理的初探

本文研究了新疆杨插穗低温层积处理前后内源抑制物和部分酶类活性的变化,植物生长素和地膜育苗对插穗生根的影响,观察了插穗的形态解剖特征。为提高新疆杨扦插成活率找到了一些科学依据     

Organic Farming Affects C and N in Soils Under Olive Groves in Mediterranean Areas

Under semiarid climatic conditions, intensive tillage increases soil organic matter losses, reduces soil quality, and contributes to climate change due to increased CO₂ emissions. There is a need for an agricultural management increasing soil organic matter. This paper presents the organic carbon (OC) and nitrogen (N) stocks, C:N ratio and stratification ratios (SRs) of these properties for olive groves soils under long‐term organic farming (OF), and conventional tillage (CT) in Los Pedroches valley, southern Spain. The results show that OF increased C and N stocks. The soil organic carbon (SOC) stock was 73·6 Mg ha⁻¹ in OF and 54·4 Mg ha⁻¹ in CT; and the total nitrogen (TN) stock was 7·1 Mg ha⁻¹ and 5·8 Mg ha⁻¹ for OF and CT, respectively. In the surface horizon (A: 0–16·9 cm in OF and Ap: 0–21·8 cm in CT) and Bw horizon (16·9–49·6 cm in OF and 21·8–56 cm in CT), SOC and TN concentrations and C:N ratios were higher in OF than in CT. Soil properties stratification in depth, expressed as a ratio, indicates the soil quality under different soil management systems. The SR of SOC ranged from 2·2 to 3·1 in OF and from 2·1 to 2·2 in CT. However, only SR2 (defined by Ap‐A/C) showed significant differences between CT and OF. The SR of TN showed similar trends to that of the SR of SOC. Organic farming contributes to a better soil quality and to increased carbon sequestration. Copyright © 2013 John Wiley & Sons, Ltd.     

黄河上游退耕地植被组成、结构及水保功能评价

 面对黄河上游地区生态失衡的严重现实,作为植被恢复重建重要手段的退耕还林还草工程,其水保功能研究不仅具有理论价值,而且有十分迫切的实践需要。退耕地人工植被的建立,是一种仿拟自然植被的过程,植物种数越多,垂直层次性越复杂,植被的水保功能也越高。在黄河上游脑山区,物种丰富度指数最高的阶段,往往为植物群落演替的中间阶段,此时植物层次较多,一般可达3～5层,种类繁杂,生物基因保存多;同时,多层次的植物群落结构,对降水的截留作用明显,水保功能突出,以青海云杉为主的针阔混交类型,就是其典型代表之一。退耕地植被随着林分年龄增加,其水保功能逐步提高。一些退耕20多年的人工植被类型,生物多样性高,垂直层次结构复杂,水保功能甚至超过一些天然植被类型,直逼水保功能表现最好的50多年生天然青海云杉针阔混交林。在退耕还林还草工作中,通过仿拟自然植被结构,建造复层、混交的植被类型,来实现稳定的退耕地人工植被水保功能的整体思路,是切实可行的。     

北方农牧交错带(武川县)土壤微生物数量分布及层化比率研究

采用田间采样及室内培养方法，对内蒙古武川县耕地、退耕还灌地和放牧草原3种类型土地土壤微生物各类群的数量分布和层化比率进行了研究。结果表明：在土壤耕作层（0～30cm）土壤微生物数量呈逐层下降趋势，3种类型土地的土壤微生物总数相差不大，3种类型土地土壤微生物层化比率存在明显差异。同时提出了土壤微生物层化比率的概念，并认为土壤微生物层化比率可能是一个比较好的指示动态土壤质量（土壤演替方向）的指标，当一个区域土壤微生物层化比率大于2时，土地一般不会发生退化现象。在研究的3块实验区域中，耕地存在较高的退化风险．退耕还灌地正处于逐步恢复的阶段，放牧草原依然存在逐步退化的趋势。     

长柄双花木种子休眠与萌发的初步研究

长柄双花木种子的种皮占种子风干重 6 0 .2 %。种子透水性良好。浓硫酸处理 11h后 ,可使种皮减轻重量约占种子总重量的 11.32 % ,加强了种子的透气性并减弱了种皮的机械束缚力。酸蚀 11h的种子 ,与拌有 5 0 0 mg·L- 1 GA3湿沙相混并经一冬层积后 ,可获 38.9%的出苗率 ,而对照则颗粒不发。破除休眠后种子的萌发温度以 2 0℃为宜。     

Physical variability in Prince William Sound during the SEA Study (1994–98)

From 1994 to 1998, a multidisciplinary ecosystem study (the Sound Ecosystem Assessment) examined the primary physical and biological factors that influence the production of pink salmon and Pacific herring in Prince William Sound (PWS), species that experienced population declines after the 1989 Exxon‐Valdez oil spill. Three physical processes are described that influence ecosystem processes: surface layer stratification; upper layer (<100 m) circulation; and exchange between PWS and the northern Gulf of Alaska (NGOA). Stratification formed first in the PWS nearshore regions in March, and subsequently in the northern central basin in April, primarily due to freshening. The northern stratified layer and the associated zonal density front persisted at least through June, but year‐to‐year differences occurred. In spring and summer, circulation in central PWS could be either cyclonic or anticyclonic. Drifter trajectories often linked central PWS to a nearshore bay or fjord, or one bay or fjord to another. September was characterized by a cyclonic circulation and isopycnal doming in central PWS, with little year‐to‐year variability. At Hinchinbrook Entrance, a main connection with the Gulf of Alaska, alternating inflows and outflows occurred in spring over all depths. In summer through early autumn (1995), in the absence of predominantly westward winds, the dominant exchange pattern was outflow above about 150 m and inflow below. In summer through early autumn (1996–98), there was also surface (<20 m) inflow at Montague Strait (the other main entrance). Northward transport at Hinchinbrook Entrance was maximum in late autumn through winter, with inflow above ~150 m and outflow below. Westward wind events over the shelf associated with the weather cycle drove inflow events at both Hinchinbrook Entrance and Montague Strait that may result in transport of zooplankton important to the PWS ecosystem.     

海桐种子的休眠解除与萌发

观赏植物海桐(Pittosporum tobira(Thunb.)Ait.)种子的休眠和萌发特性已被进行了较充分的研究.TTC检测出新鲜海桐种子是高活力的(98%),但在5个恒温和1个变温(12 h/d的光周期)下,其萌发率仅为27%,这说明海桐种子处于休眠状态.经不同浓度(100mM和200 mM)的GA3溶液处理后,新鲜海桐种子的萌发率有所提高;在25/15℃与200 mM的处理下,其发芽率最高是41%,但仍不理想.当经过低温(5℃)处理一段时间(15、30、45、60、90d)后,海桐种子的萌发率显著提高,尤其是在25℃和25/15℃处理下,萌发率分别为87%和95%.此外,冷层积30 d和45 d的海桐种子经200 mM的GA3溶液处理后的萌发率分别达69%和94%,效果显著.可见,海桐种子的休眠是浅生理休眠,单一的GA3溶液处理不能有效地打破海桐种子的休眠,但冷层积90d或200mM GA3溶液处理冷层积45d的种子,可有效地解除其休眠;同时,温度对种子的萌发有较大影响,在适宜的萌发温度(25℃或25/15℃)与周期性(12h/d)光照下,种子的萌发率超过90%.由此推断,海桐种子在自然条件下难以萌发的原因与其生理休眠有关.     

水库低温水的生态影响及工程对策研究

大型水库低温水下泄对农业生态和水生生态产生较大不利影响, 国内在高坝大库设计中多采用叠梁门表层取水结构来获取满足农作物的灌溉水温和鱼类生活史需求水温, 其运用的下泄水温调节效果多采用立面二维或垂向一维水温模型进行模拟。文中利用MIKE3软件建立研究水库的三维水温数学模型, 精确模拟水库采用叠梁门分层取水和单层进水口两种取水方案下的水库水温结构及下泄水温。预测结果表明叠梁门分层取水方案能有效地提高水库泄水温度, 3~9月出现的水库低温水温度比单层进水口提高2~4 ℃, 并在5月份就能达到鱼类产卵要求的18.4 ℃。叠梁门分层取水结构能够有效地提高水库泄水温度, 最大程度减缓水库低温水下泄的生态影响, 实现生态环境保护和经济效益的较好协调, 叠梁门结构比较适合作为国内生态友好型大型水库工程建设的生态修复和保护措施。     

不同预处理对金银忍冬种子发芽率的影响

通过5、10、15℃的层积,以及不同浓度、不同时间的药剂浸泡,测定金银忍冬的发芽率,探索提高金银忍冬发芽率的预处理方法。结果表明:金银忍冬10℃层积处理14 d最高发芽率为90%,明显好于药剂处理和清水浸泡,层积处理提高金银忍冬种子的发芽率,但层积时间和层积温度对金银忍冬种子发芽率在检验水平α=0.001差异显著。