贵州桦木资源现状与开发利用策略

贵州桦木种类有7个,其中桦木属有4个种,桤木属有3个种。光皮桦和旱冬瓜是分布最广的两个种,全省各地均有分布。传统林业主产区的现有桦木资源数量比非主产区小,现有桦木资源以中、幼林为主,中、幼林的面积和蓄积超过98%,近、成熟林和过熟林资源相对非常少。贵州桦木资源开发利用应系统开展良种选育研究,加强抚育管理、综合改造"三低"林分,科学规划、合理布局良种基地,采用良种良法营造高效用材林基地。     

利用光合细菌处理高浓度有机废水

通过对光合细菌法处理高浓度有机废水的原理、工艺、优缺点分析,提出在同样成本费用下,此法是更合理的选择。     

负载型TiO2薄膜光催化剂降解亚甲基蓝

采用溶胶-凝胶法制备了玻璃负载的TiO2薄膜光催化剂，研究了该催化剂对亚甲基蓝溶液的光催化降解，考察了反应时间、水样的初始浓度、溶液的pH等对光催化降解效果的影响。     

基于鱼类产卵期栖息地需求的水库生态调度方法研究

为减轻水利工程建设对水库库区及水库下游造成的不利生态影响,针对减水河段鱼类产卵繁殖的有效保护问题,以鱼类产卵期栖息地生境需求作为主要生态约束因子,结合生态水力学法、目标物种栖息地生态水文学特征的数字化处理与水温适宜性,建立了考虑鱼类产卵期栖息地需求的生态调度过程确定方法,以古水电站为例,选取光唇裂腹鱼为主要保护对象,获得了古水电站的生态调度过程,较好地保留了天然径流过程的涨落水变化和流量脉冲过程对光唇裂腹鱼产卵刺激的水文信息,使得光唇裂腹鱼获得更适宜的水力学环境,提升产卵概率,有效保护鱼类资源。     

吸附-双催化氧化降解苯胺、硝基苯废水

苯胺、硝基苯废水利用吸附树脂吸附后,再利用过氧化氢作氧化剂,在亚铁离子和紫外光的双催化下氧化降解。通过对亚铁离子浓度、过氧化氢浓度等因素对光降解影响的考察,结果表明,在实验条件下,本氧化体系对苯胺、硝基苯废水有明显的降解效果,苯胺、硝基苯废水经该体系处理12h后,去除率最高分别达到99.7%和95.3%。     

纳米TiO2光催化降解技术在污水处理中的应用

光催化技术是一种新兴的高效节能现代污水处理技术，目前大部分还处于实验研究阶段。本文介绍了TiO2光催化降解水中有机物的机理以及pH值、载体、外加氧化剂等对其光催化活性的影响，TiO2光催化剂的表面修饰及与其它技术的联用情况。讨论了光电催化、太阳能利用等对光催化领域的推动作用，并指出在该领域的研究中存在问题和发展方向。     

钼酸盐光度法测定水质中总磷过程中色度浊度的校正方法比较

钼酸盐光度法在对水质中总磷测定过程中,可能存在色度浊度的干扰问题,对光度法的测定有一定的影响。对常见的几种色度浊度去除方法做了试验对比,并对每种去除干扰的方法给出一定的应用范围。     

不同培养条件对软枣猕猴桃试管苗玻璃化的影响

以MS为基本培养基，研究生长调节剂、琼脂、光照、温度等因素对光叶楮试管苗玻璃化的影响。结果表明，最佳生长调节剂的配比为1．0mg／LBA＋0．5mg/L NAA、琼脂浓度7．0-8．0g／L、光照强度3000lx、培养温度25％。该优化培养条件能有效防止玻璃化苗的发生，获得较高的增殖系数和较健壮的苗木，且能降低生产成本。     

迎阳报春种子萌发特性研究

通过种子萌发试验,研究了光照、温度、赤霉素对迎阳报春种子萌发的影响,同时对其种子形态进行了观测.结果表明,迎阳报春成熟种子为黄褐色,呈不规则卵圆形或多面形,种子细小,千粒重为89.52±0.25mg.种子萌发的适宜温度为20℃,对光敏感,光照条件下萌发率较高,萌发进程较快;种子经赤霉素处理后,萌发持续时间缩短,但对种子最终发芽率、发芽势影响不显著.     

纳米光催化剂制备及处理印染废水的研究

采用水热法制备了三氧化钨/石墨烯光催化材料,并利用X-射线衍射和扫描电子显微镜对光催化材料进行表征,模拟降解印染废水(罗丹明B溶液)考察其光催化反应活性。通过调整不同反应温度、反应时间以及石墨烯掺杂量等参数,结果发现反应温度120℃、反应时间12h时,三氧化钨/石墨烯光催化材料光催化活性最好,在光照2h后废水降解率可以达90%以上。     

Remediation of heavy metal-contaminated forest soil using recycled organic matter and native woody plants

The main aim of this study was to determine how the application of a mulch cover (a mixture of household biocompost and woodchips) onto heavy metal-polluted forest soil affects (i) long-term survival and growth of planted dwarf shrubs and tree seedlings and (ii) natural revegetation. Native woody plants (Pinus sylvestris, Betula pubescens, Empetrum nigrum, and Arctostaphylos uva-ursi) were planted in mulch pockets on mulch-covered and uncovered plots in summer 1996 in a highly polluted Scots pine stand in southwest Finland. Spreading a mulch layer on the soil surface was essential for the recolonization of natural vegetation and increased dwarf shrub survival, partly through protection against drought. Despite initial mortality, transplant establishment was relatively successful during the following 10 yr. Tree species had higher survival rates, but the dwarf shrubs covered a larger area of the soil surface during the experiment. Especially E. nigrum and P. sylvestris proved to be suitable for revegetating heavy metal-polluted and degraded forests. Natural recolonization of pioneer species (e.g., Epilobium angustifolium, Taraxacum coll., and grasses) and tree seedlings (P. sylvestris, Betula sp., and Salix sp.) was strongly enhanced on the mulched plots, whereas there was no natural vegetation on the untreated plots. These results indicate that a heavy metal-polluted site can be ecologically remediated without having to remove the soil. Household compost and woodchips are low-cost mulching materials that are suitable for restoring heavy metal-polluted soil.     

Leaching of nitrogen and phosphorus during production of forest seedlings in containers

Little information is available concerning the contamination risk caused by forest seedling nurseries to local surface and ground waters compared with agricultural and horticultural production. Leaching of nitrogen (N) and phosphorus (P) through peat growing medium in containers and nutrient uptake of seedlings were monitored in production of silver birch (Betula pendula Roth), Norway spruce [Picea abies (L.) Karst], and Scots pine (Pinus sylvestris L.) seedlings. About half of the applied nutrients (total amount applied = 149 to 260 kg N ha(-1) and 60 to 108 kg P ha(-1)) was premixed into the peat medium, as is usual in Finnish nursery practice, and the other half was applied to seedlings in liquid form with mobile booms. Depending on tree species, 11 to 19% of the applied N was recovered in leachates and 15 to 63% in seedlings. The undiscovered proportion varied from 19 to 71%. The amounts of leached N were 19 to 41 kg ha(-1). Only 5 to 31% of the applied P was recovered in seedlings; 16 to 64% (11 to 56 kg ha(-1)) was found in leachates. Total N and P load to the environment may increase substantially if nutrients applied in liquid fertilization outside container trays are included. Consequently, it is important to determine the sources of nutrient load in container seedling production to mitigate the risk of environment contamination.     

Prescribed burning effects on summer elk forage availability in the subalpine zone, Banff National Park, Canada

The effects of prescribed burning on forage abundance and suitability for elk (Cervus elaphus) during the snow-free season was evaluated in east-central Banff National Park, Canada. Six coniferous forest and mixed shrub-herb plant communities (n=144 plots), and 5223ha of burned (n=131) vegetation <12 years old were sampled using a stratified semi-random design. Sampling units represented various combinations of vegetation, terrain conditions, and stand ages that were derived from digital biophysical data, with plant communities the basic unit of analysis. Burning coniferous forest stands reduced woody biomass, and increased herbaceous forage from 146 to 790 kg/ha. Increases commonly occurred in the percent cover of hairy wild rye (Leymus innovatus (Beal) Pigler) and fireweed (Chamerion angustifolium (L.) Holub.). The herbaceous components of mixed shrub-herb communities increased from 336-747 kg/ha to 517-1104 kg/ha in response to burning (P<0.025, Mann-Whitney U-test). Browse biomass (mostly Salix spp. and Betula nana L.) increased >or=220% (P相似文献   

Root penetration of sealing layers made of fly ash and sewage sludge

Fly ash and sewage sludge are suggested materials for constructing sealing layers covering mine tailings impoundments. Little is known, however, of their effect on vegetation or resistance to root penetration. We investigate: (i) the ability of different plant species to grow in sealing layers comprising fly ash and sewage sludge, (ii) the impact on plant growth of freshly hardened fly ash compared to aged and leached ash, and (iii) the plant stress response to fly ashes of different properties. A 6-mo greenhouse study using birch (Betula pendula Roth.), Scots pine (Pinus sylvestris L.), Kentucky bluegrass (Poa pratensis L.), and willow (Salix viminalis L.) demonstrated that no roots could grow into a compacted layer consisting only of ash, while a 6:4, ash-sludge mixture admitted roots into the upper part and a 1:9, ash-sludge mixture was totally penetrated (to 15 cm in depth) by roots of willow and Scots pine. Freshly hardened ash prevented root growth more effectively than aged ash did, as was observed in tests using reed canarygrass (Phalaris arundinacea L.) and pea (Pisum sativum L.). Furthermore, extracts of highly alkaline ash were more toxic to pea in a 48-h toxicity test than less alkaline ash was. However, stress responses to diluted ash extracts of lower pH, measured as enzyme capacities in dwarf bean (Phaseolus vulgaris L.), were more related to the metal and ion contents. Root penetration of sealing layers is most effectively prevented if little sewage sludge is added, and if ash of high alkalinity is chosen.     

Methane Emissions and Production Potentials of Forest Swamp Wetlands in the Eastern Great Xing’an Mountains, Northeast China

Measurements of methane flux at a few inundated sites in China have been extrapolated to obtain estimates on a national scale. To enable those national estimates to be refined and to compare flux from geographically separated sites comprising the same wetland types, we used a closed chamber method to measure methane flux in uninundated Betula platyphylla—and Larix gmelinii—dominated peatlands in the Northeast China. Our measurements were taken from both vegetated and bare soil surfaces, and we compared flux with environmental measures including vegetation biomass, soil temperature and soil characteristics. We found that methane flux was low, and that there were no significant differences between wetland types, indicating that environmental influences were dominant. We found that flux was positively correlated to temperature in the surface layers of the soil, the above-ground biomass of the shrub and herb layers, total soil carbon and total soil nitrogen; and we suggest that emissions may be due to anaerobic microcosms in the surface layers. The methane production potentials of the soils were low and similar between both sites but inconsistent with the differences between fluxes, and inconsistent with production potentials and fluxes reported from the same wetland types elsewhere, indicating that there were subtle environmental differences between wetlands classed as being of the same type. Differences between fluxes in vegetated chambers with bare soil chambers were insignificant, indicating that no methane emission through aerenchyma occurred at our sites. We concluded that wetland type was not an accurate predictor of methane flux.     

Vegetation succession and impacts of biointrusion on covers used to limit acid mine drainage

A cover with capillary barrier effects (CCBE) was constructed in 1998 on the abandoned Lorraine mine tailings impoundment to limit the generation of acid mine drainage. The Ministry of Natural Resources and Fauna of Quebec (MRNF) is responsible for the site and for all restoration works on it, including CCBE construction. The CCBE is made up of three layers: a 0.3-m layer of sand used as a support and capillary break layer; a moisture-retaining layer with a thickness of 0.5 m (this layer is constructed of a nonplastic silt); and a 0.3-m sand and gravel layer on top. The main objective of the CCBE is to maintain one (or more) of the layers at a high degree of water saturation to impede oxygen migration and acid generation. Vegetation succession on the Lorraine CCBE results in an improvement in soil conditions, leading to the installation of deep-rooted species, which could represent a risk to CCBE long-term performance. Hence, the characterization of vegetation succession is an important aspect of the monitoring strategy for the Lorraine CCBE. Species occurrence was documented, and depth of tree roots was measured by excavation on a regular basis. Eight functional groups of plants were identified; herbaceous plants were the most abundant ecological plant groups. Tree ring counts confirmed that tree colonization started the year of CCBE construction (1999). Of the 11 tree species identified, the most abundant were poplar (Populus spp.), paper birch (Betula payrifera Marsh.), black spruce (Picea mariana Mill.), and willow (Salix spp.). Significant differences in occurrence related to environmental conditions were observed for most functional groups. Root excavation showed that tree roots exceeded the depth of the protective layer and started to reach the moisture-retaining layer; in 2008, root average depth was 0.4 m and the maximal root depth was 1.7 m.     

Development of Customized Fire Behavior Fuel Models for Boreal Forests of Northeastern China

Knowledge of forest fuels and their potential fire behavior across a landscape is essential in fire management. Four customized fire behavior fuel models that differed significantly in fuels characteristics and environmental conditions were identified using hierarchical cluster analysis based on fuels data collected across a boreal forest landscape in northeastern China. Fuel model I represented the dense and heavily branched Pinus pumila shrubland which has significant fine live woody fuels. These forests occur mainly at higher mountain elevations. Fuel model II is applicable to forests dominated by Betula platyphylla and Populus davidiana occurring in native forests on hill slopes or at low mountain elevations. This fuel model was differentiated from other fuel models by higher herbaceous cover and lower fine live woody loading. The primary coniferous forests dominated by Larix gmelini and Pinus sylvestris L. var. mongolica were classified as fuel model III and fuel model IV. Those fuel models differed from one another in average cover and height of understory shrub and herbaceous layers as well as in aspect. The potential fire behavior for each fuel model was simulated with the BehavePlus5.0 fire behavior prediction system. The simulation results indicated that the Pinus pumila shrubland fuels had the most severe fire behavior for the 97th percentile weather condition, and had the least severe fire behavior under 90th percentile weather condition. Fuel model II presented the least severe fire potential across weather conditions. Fuel model IV resulted in greater fire severity than Fuel model III across the two weather scenarios that were examined.     

Climatic and stream-flow controls on tree growth in a Western montane riparian forest

Humans have severely impacted riparian ecosystems through water diversions, impoundments, and consumptive uses. Effective management of these important areas is becoming an increasingly high priority of land managers, particularly as municipal, industrial, and recreational demands for water increase. We examined radial tree growth of four riparian tree species (Pinus jeffreyi, Populus trichocarpa, Betula occidentalis, and Pinus monophylla) along Bishop Creek, California, and developed models relating basal area increment (BAI) and relative basal area increment (RBAI) to climatic and stream flow variables. Between years 1995–1999, univariate regression analysis with stream flow explained 29 to 61% of the variation in BAI and RBAI among all species except P. trichocarpa; growth by P. trichocarpa was not significantly related to stream flows over this period. Stepwise linear regression indicated that species responded differently to climatic variables, and models based on these variables explained between 33 to 86% of variation in BAI and RBAI during the decade of the 1990s. We examined branch growth of P. trichocarpa for sensitivity to differences in stream flow regimes and found that annual branch growth did not vary between a high- and low-flow site, but that annual branch growth was significantly higher in wet years with greater stream flows. Our results support the establishment of site-specific management goals by land managers that take into account all of the important tree species present in riparian ecosystems and their differential responses to altered hydrologic condition. Instream flow requirements for maintaining tree growth and vigor are only one of the species-specific responses that need to be evaluated, and these assessments should attempt to separate experimentally stream-flow (managed) controls from climatic (unmanaged) controls on growth.     

LAKE EUTROPHICATION–A NATURAL PROCESS1

Lake eutrophication is an economic, recreational, and aesthetic problem that affects every lake of the world. Eutrophication is the natural process of lake aging, and progresses irrespective of man's activities. Pollution, however, can hasten the natural rate of aging and shorten the life expectancy of a body of water. The eutrophication of a lake consists of the gradual progression from one life stage to another based on the degree of nourishment or productivity. The extinction of a lake is attributed to enrichment by nutritive materials, biological productivity, decay, and sedimentation. Presently used methods for retarding eutrophication are the abatement of cultural enrichment, treatment of eutrophic symptoms, and control of fundamental causes.