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11.
To improve the productivity of poplar plantations, a field experiment of split-plot design with four tree spacings and three poplar clones was established, and four soil enzyme activities and microbial biomass were monitored in the trial.Soil enzyme activities, in most cases,were significantly higher in topsoil(0–10 cm) than in lower horizons(10–20 cm).Soil cellulase, catalase and protease activities during the growing season were higher than during the non-growing season, while invertase activity followed the opposite trend.Soil invertase, cellulase and catalase activities varied by poplar clone but soil protease activity did not.Cellulase and protease activities in the plantation at 5×5 m spacing were significantly higher than in the other spacings.The highest catalase activity was recorded at 6×6 m spacing.At the same planting density, invertase activity was greater in square spacings than in rectangular spacings.Soil microbial biomass was also significantly affected by seedling spacing and poplar clone.The mean soil MBC was significantly lower in topsoil than in the lower horizon, while MBN showed the opposite pattern.Significantly positive correlations were observed among soil cellulase, protease and catalase activities(p0.01), whereas soil invertase activity was negatively and significantly correlated with cellulase, protease and catalase activities(p0.01).Soil microbial biomass and enzyme activities were not correlated except for a significantly negative correlation between soil MBC and catalase activities.Variations in soil enzyme activity and microbial biomass in different poplar plantations suggest that genotype and planting spacing should be considered when modeling soil nutrient dynamics and managing for long-term site productivity. 相似文献
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种子休眠广泛存在于木本植物, 且其原因复杂多样, 休眠程度深浅不一, 这是目前木本植物种子休眠与萌发的分子生物学研究的主要瓶颈。文中根据Baskin的分类系统, 总结了一些林木种子休眠的归属类型; 对以欧洲水青冈、挪威槭、欧亚槭为阔叶树模式植物的种子休眠, 种子萌发的分子生物学研究进行了综述; 指出相关研究仅限于少量树种的生理休眠类型及与有限领域如激素(ABA、GA及乙烯)信号传导相关的基因及表达和蛋白及其功能, 更多方面如代谢途径、光对种子萌发的调控等研究还有待加强。 相似文献
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经营措施对林地长期生产力影响的研究策略 总被引:2,自引:0,他引:2
随着社会对木材需求量的增大及更多的天然林被划为环境保护林,人工林在未来木材生产中将起越来越大的作用,致使林地长期生产力的维护问题引起了全世界的重视.主要介绍了经营措施对林地长期生产力影响的研究策略,并比较了演替时序研究、追溯研究及长期定位试验3种研究方法的优缺点及应用概况. 相似文献
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青钱柳叶总黄酮大孔树脂纯化工艺 总被引:3,自引:0,他引:3
为提高青钱柳叶总黄酮的纯度,筛选适宜青钱柳叶总黄酮纯化的大孔树脂,确定青钱柳叶总黄酮纯化工艺参数,选用大孔树脂材料,采用静态与动态吸附-解吸方法对青钱柳叶总黄酮进行纯化,以吸附量与洗脱率为考察指标对树脂进行选择与工艺研究,并利用紫外可见分光光度计测量青钱柳叶总黄酮的含量.结果表明:AB-8型大孔树脂纯化效果最好,其最佳工艺为进样速度2 BV/h、进样质量浓度1.0 mg/mL,洗脱剂最适宜体积分数与洗脱速度分别为70%和2 BV/h.表明AB-8型大孔树脂适合青钱柳叶总黄酮的纯化. 相似文献
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Cyclocarya paliurus is a highly valued and multiple function tree species. There has been increasing interest in planting and managing C. paliurus for timber production and medical use owing to loss of harvestable acreage. Seed from six provenances was collected from the main natural range of this species. Significant variation in growth and wood properties was measured among the six provenances at age 7 years. Provenance mean height and DBH varied significantly from 730–991 and 6.7–10.0 cm, whereas provenance means of wood basic density and crystallinity ranged from 463–554 kg m?3 and 51.4–74.1 %, respectively. Mean provenance microfibril angle (MFA) at breast height ranged from 18.1° to 23.2°, while MFA at breast height varied from 11.0° to 34.5° among growth rings which showed a consistent pith-to-bark trend of declining angles. There was no significant relationship of growth rate with latitude or longitude of seed sources, however, provenances from low latitude and longitude grew faster at the trial site. Wood quality was significantly related to latitude of seed sources, showing a positive correlation for both wood basic density and wood crystallinity, but a highly negative association with MFA. Significant correlations between wood properties measured indicated that there exists a great opportunity to improve wood quality of C. paliurus through selection of juvenile trees with low MFA. 相似文献
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New Forests - As a multiple function tree species, Cyclocarya paliurus is planted and managed for timber production and medicinal use. However, it remains unclear to what extent geographical... 相似文献
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With economic incentives and interests in fast-growing poplar trees for short-rotation production of fiber and veneer, many new poplar hybrids have been bred and planted in China, but how to match the new poplar clones to suitable sites and maintain their higher growth rates is still not very clear. In this study, the photosynthetic response of poplar leaves at various developmental stages during two seasons (summer and autumn) was explored and mechanistic models for the photosynthesis of poplar leaves at different developmental phases in response photosynthetic active radiation (PAR), temperature, and relatively humidity were established using the optimization software package 1st Opt. Mature poplar leaves in autumn had significantly higher photosynthetic capacity than leaves at other stages and seasons. Based on the models established for poplar leaves at different phases, the main limiting factors for photosynthesis at the research site were high PAR and temperature in the summer and low PAR in the autumn. Our results highlight the importance of selecting suitable sites, pruning and stand density control during the plantation development to maintain higher photosynthetic rates of poplar trees and to establish optimum cultivation patterns for various utilization of poplar plantations. 相似文献
19.
Poplar-based agroforestry systems are one of the most important farming systems on the temperate plains of China, but soil respiration in those systems has seldom been reported. In this study, poplar leaf litter and residues of the two main crops (wheat and peanut) grown in the agroforestry system were amended to form different litter mixing treatments in field experiments at two sites located in Jiangsu Province, China. We measured soil respiration and environmental factors in the different treatments. Soil respiration rates were increased by the addition of plant residues but were strongly influenced by residue quality. During the growing season, soil respiration was negatively related with C/N ratio, while positively related with the initial P concentration of residues (P < 0.05). Poplar leaf litter and crop residues showed non-additive effects on soil respiration when they were mixed. Both air and soil temperature at 10 cm depth explained more than 85 % of the variation of soil respiration at both sites with an exponential model. A significant linear relationship between soil respiration and soil water content at 10 cm depth (WS) was also observed. The percent of variation in soil respiration explained by a model based on air temperature and soil water content was greater than that explained by a model based on temperature alone. Thus, soil respiration in the studied poplar-based agroforestry systems was driven by both temperature and soil water content. Soil respiration was significantly different between the two sites that had different clay content and C/N ratios. Results from this study are important for us to understand how soil respiration responds to litter mixing or is influenced by biophysical factors in poplar-based agroforestry systems. 相似文献
20.
Contrasting decomposition rates and nutrient release patterns in mixed vs singular species litter in agroforestry systems 总被引:1,自引:1,他引:0
Yikun Wang Scott X. Chang Shengzuo Fang Ye Tian 《Journal of Soils and Sediments》2014,14(6):1071-1081