蒙古栎叶,果实成分分析

通过对蒙古栎叶、果实的成分分析,证实蒙古栎叶中含有糖、蛋白质、脂肪、单宁、叶绿素、灰分、维生素、果胶、１７种氨基酸及２０种微量元素;蒙古栎果实中含有蛋白质、脂肪、淀粉、维生素Ｄ２、１７种氨基酸及２０种微量元素．     

木薯酒中的主要化学成份及其对酒质的影响

通过气相色谱—质谱联合仪对木薯酒成份的分析, 讨论了木薯酒产生异味的原因, 并提出改善木薯酒质量的措施．     

柱前衍生-高效液相色谱法测定浒苔多糖的组成

研究了浒苔多糖样品经三氟乙酸完全水解而无损失的最适条件,并且在优化流动相洗脱程序等色谱条件的基础上,建立了1-苯基-3-甲基-5-吡唑啉酮(PMP)柱前衍生-高效液相色谱法分析浒苔多糖的单糖组成及含量的方法。该方法采用配备紫外检测器的高效液相色谱仪,在250 nm波长下进行测定,外标法定量。结果表明,在此条件下,8种单糖能够良好分离,各单糖在1-100μg/ml范围内具有良好的线性关系,相关系数r≥0.999,回收率在76.0%-108%之间,相对标准偏差RSD10%。采用该方法对浒苔多糖样品进行组成及含量分析,发现无论样品原料为何种浒苔,浒苔多糖均以鼠李糖为主,同时还含有葡萄糖醛酸、葡萄糖、木糖、半乳糖以及少量的甘露糖、半乳糖醛酸和岩藻糖。     

海参中单糖检测方法的建立及含量测定

本研究建立了高效阴离子交换–脉冲安培检测法(HPAEC-PAD)分析海参(Apostichopus japonicus)多糖的单糖组成及含量测定。通过比较3种蛋白去除法对海参多糖含量的影响,优化海参多糖纯化方法;比较淋洗液浓度对单糖分离效果的影响,优化海参中单糖分离的色谱条件。结果显示,Sevag法去蛋白的效果最好,在淋洗液为20 mmol/L Na OH的条件下分离岩藻糖、氨基半乳糖、氨基葡萄糖、半乳糖、甘露糖、阿拉伯糖、葡萄糖和乳糖;在淋洗液为160 mmol/L Na OH和200 mmol/L Na AC的条件下分离葡萄糖醛酸和半乳糖醛酸。各单糖标准曲线的线性相关系数不低于0.998,检出限为2.5~50μg/L,加标回收率在83.6%~113.1%之间。该方法可测定海参多糖的中性糖、氨基糖和糖醛酸,可作为海参及其制品中的单糖分析及定量方法,为相关标准的制定提供参考。     

不同移栽方式对烤烟‘KRK26’生长发育和产质量影响研究

为研究不同移栽方式对烤烟‘KRK26’生长发育和产、质量影响,进行了膜下小苗移栽与膜上壮苗移栽对比试验。结果表明,膜下小苗移栽方式能有效促进烤烟生长发育,缩短烤烟大田生育期,烟叶成熟期提前8天。同时改善烟叶外观质量,化学成分更加协调,使烟叶单产提高10.5%,上等烟率提高0.9%,产值提高11.3%。试验证明了德宏烟区膜下小苗移栽的优势,为德宏烟区烤烟最佳移栽方式提供依据。     

Effects of Soil Characteristics on Spring-Harvested Switchgrass Biomass Composition

Switchgrass (Panicum virgatum L.) is a promising bioenergy crop for temperate regions. Overwintering has been used to improve biomass quality, resulting in a more efficient combustion, partially due to a reduction in minerals concentration. This study examines the effects of soil composition on overwintered switchgrass composition. Samples were collected in the spring from 58 environments in Southern Quebec to determine possible relationships between soil composition and biomass quality. Principal component analysis and stepwise regressions were used to identify relationships between soil and biomass compositions. Soil parameters monitored explained 74% of the variation in biomass silicon (Si) concentration, 45% of the variation in ash, and 32% of the variation in magnesium (Mg). Soil composition had limited effects on the concentration of other elements in switchgrass biomass. Switchgrass biomass quality is influenced by soil composition and appears well suited to biomass combustion when overwintered and harvested in the spring.     

Temporal dynamics of forage succession for elk at two scales: Implications of forest management

Rapid conversion of lodgepole pine (Pinus contorta) dominated landscapes in western Alberta to a mosaic of successional stand ages has long-term implications for elk populations in the region that have not been fully assessed. We developed stand-level models of forage succession using data from 159 cutblocks to simulate forage and cover availability within the home range of an elk under “even-flow” and “pulsed” timber cutting scenarios that are common in this area. We found forage biomass peaked approximately 9 years following felling for both herbaceous (graminoids and forbs) and palatable browse forage. Forage production was determined primarily by the age of the cutblock (time since felling) and to a lesser extent elevation, compound topographic index (a measure of site wetness), and the distance to the nearest deciduous forest patch. Forbs became increasingly abundant as stands matured. Browse composition shifted from palatable species to unpalatable species after approximately 30 years. Within an elk home range (100 km²), we found that simulating an “even-flow” cutting regime resulted in forage availability that was always higher than under the current conditions of 90% forests when more than 10 ha were harvested per year. Further, forest cover (>30$>30$-year-old stands) was never less than the guideline of 60% of the area needed to provide adequate thermal and hiding cover. In contrast, when a “pulsed” harvest scenario was simulated, similar to what occurs for mountain pine beetle control, forage availability changed dramatically over time as a large cohort of harvested timber aged. Without further harvesting the stand conditions in the home range eventually returned to a state of pre-harvest risk for mountain pine beetle outbreak. We demonstrated several additional harvesting scenarios that avoided the potential risk and produced a much higher level of forage than currently exists.     

Short-term response of the herbaceous layer within leave patches after harvest

Leave patches, uncut areas in a harvested forest, may conserve herbaceous layer species that decline after forest clearcutting. They may also serve to maintain source populations for the recolonization of the harvest area. The main objective of this study is to characterize the short-term response of the herbaceous layer to clearcut harvesting disturbance within and adjacent to leave patches. Four experimental 1 ha patches and two uncut references were established. Within each patch or reference, belts of five 1 m² quadrats were placed at 50 m and 5 m outside the patch, at 0 m (edge), and at 25 m, 35 m, and 50 m (centre) inside. These belts of quadrats were replicated at all four aspects (North, South, East, and West). Ground vegetation was sampled yearly for 1 year before harvest and 3 years after harvest in the experimental patches and for 2 consecutive years in the references. Some common residual species declined significantly in the clearcuts, but remained stable inside the patches in the short term (3 years after harvest). Overall species composition changed little in the patch interior and edge after harvest. Colonizing species (those that appeared in quadrats after harvest) in the patch exterior were predominantly early-seral species, whereas colonizers in the patch interior tended to be shade-tolerant forest species. Species were grouped a priori based on two habitat preferences (amounts of canopy cover and disturbed substrate). Species characteristic of a habitat with closed canopy and undisturbed substrates that decreased significantly over time in the patch exterior were negatively correlated with the amount of exposed mineral soil and open canopy. Species characteristic of a habitat with open canopy and disturbed substrates that increased significantly at the patch exterior showed a positive correlation with the amount of exposed mineral soil and open canopy. No species’ habitat preference groups declined significantly in the patch interior or edge over time. Based on species’ responses to forest operations, it appears that at least the common forest species are maintained in the short term within leave patches.     

Determinants of floodplain forest development illustrated by the example of the floodplain forest in the District of Leipzig

This paper discusses determinants of the historical and current spatial extent of the floodplain forest in Leipzig as well as its tree species composition using a GIS-data based delineation model and historical forest inventories for the floodplain forest in the district of Leipzig in Germany from the 19th to the 20th century. We found that the spatial extent of the floodplain forest remained considerably stable in spite of an overall decline in the entire floodplain area from the period where the city first experienced industrialisation in the 19th century to now. However, with river regulations and the alteration of forest management from coppice-with-standards forest to high forest in the 19th century, major changes can be found in the tree species composition of the floodplain forest. Comparing these findings with references from other European floodplain forests we discuss the impact of historical and current forest management as well as the city location's influence on the extent and tree species composition of urban floodplain forests. For urban forest management in particular there is a great need to integrate biophysical, historical and forestry knowledge when predicting future developmental trends.     

HPLC法测定木糖母液的组成

[目的]建立一种快速准确测定木糖母液组成的方法。[方法]采用HPLC法分析木糖母液中木糖的含量。[结果]色谱条件为流动相乙腈：水（70：30）,流速1.0ml/min,柱温20℃,进样量10μl。在上述色谱条件下,测得木糖、阿拉伯糖、葡萄糖和半乳糖保留时间分别为6．321、7．405、7．943和8．491min。木糖浓度在1～40mg/ml范围内,与峰面积呈良好的线性关系。精密吸取20mg/ml标样溶液,外标法计算,测得木糖母液中木糖、阿拉伯糖、葡萄糖和半乳糖的含量分别为38．10％、23．70％、13．80％、9．89％。结果显示,HPLC法可准确测定样品中糖类成分的含量,且重现性好,分析速度快,操作简便。[结论]该研究为生产过程中有效控制产品的质量提供了检测依据。