刨花楠开花结实习性及其种子贮藏试验初报

观察了刨花楠开花结实习性,并进行了种子不同贮藏方法试验.结果表明:刨花楠开花结实期在不同坡向上差异明显,花期阳坡早于阴坡8 ～ 10 d,果期则早4 ～ 5d;刨花楠盛花期为4月5 ～ 15日,果熟盛期为6月中下旬;不同贮藏方法和贮藏时间刨花楠种子的保存率、发芽率、发芽势均有较明显差异,以低温湿沙贮藏效果较好,贮藏半年后种子保存率达100%,发芽率、发芽势达71.67%.     

木材纤维与回收聚丙烯的热压复合工艺研究

研究了热压时间、热压温度、聚丙烯和偶联剂加入量等工艺因子对木材纤维和回收聚丙烯复合材料性能的影响。确定了压制密度为0．80g／cm3、10mm厚的木塑复合材料的最佳工艺条件为:热压温度175℃、热压时间8min、塑料加入量40％、偶联剂的加入量4％。在此条件下压制的木塑复合板材,物理力学性能中的内结合强度和吸水厚度膨胀率与中密度板的国家标准相比达到优等水平,静曲强度和弹性模量基本满足中密度板的国家标准要求。     

Variation in infiltration with landscape position: Implications for forest productivity and surface water quality

Variation of infiltration rates with landscape position influences the amount, distribution, and routing of overland flow. Knowledge of runoff patterns gives land managers the opportunity to affect changes that optimize water use efficiency and reduce the risk of water quality impacts. The objective of this study was to assess the effect of landscape position and associated soil properties on infiltration in a small (147 ha) forest/pasture watershed in the Ozark Highlands. Three previously reported studies measured infiltration rates using double ring, sprinkling, single ring, and tension infiltrometers on soils at varying landscape positions. Although large variation in infiltration rates was observed among measurement techniques, upland and side slope soils (Nixa and Clarksville) had consistently lower infiltration rates compared to the soil in the valley bottom (Razort). A conceptual understanding of watershed runoff is developed from these data that includes infiltration excess runoff from the Nixa and Clarksville soils and saturation excess runoff on the Razort soil. Management of the soil water regime based on this understanding would focus on increasing infiltration in upland soils and maintaining the Razort soil areas in forest. Forest productivity would be enhanced by increasing plant-available water in upland soils and decreasing flooding on the Razort soil. Surface water quality would be improved by reducing the transport of potential water contaminants from animal manure applied to upland pastures.     

竹笋象危害对竹材物理力学性质的影响

对受笋万纹象(Otidognathus rubriceps Chevrolot)、一字竹笋象(O.davidis Fairmaire)、大竹笋象(Cyrtatrachelus longimanus Fabricius)危害后断梢毛竹、竹腔注药防治后毛竹、正常毛竹3种竹材进行竹材抗弯强度、抗弯弹性模量和顺纹抗拉强度测定结果表明,与正常毛竹相比较,受竹笋象危害断梢毛竹差异显著,3个竹材物理力学性质指标分别下降了43.79%、39.01%、29.28%,竹腔注药防治后毛竹3个指标下降了13.87%、10.95%、9.01%,但差异不显著,不影响竹材的使用价值.     

广西大青山石灰岩山土壤理化性质的演变及其造林绿化

研究得知:该范围的石山(石灰岩山)上,在北热带气候及植被条件相互作用下,演变为一类特别肥沃的土壤——石灰土;该类土壤有机质及氮素丰富,保蓄水性能强;钙、镁、钾、铁、锰、锌等元素含量也十分丰富,故称“热带黑钙土”;石山石多土少,整体环境恶劣,而局部生境却十分优越,又因该区雨量充沛,即使石山中的石缝、石槽内,只保存5％土质,上面就会覆盖较繁茂的草、灌植被,其中不少具有较高的经济价值,同时,也易于栽培喜钙、喜肥的优良或珍贵树种。     

Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands

Changes in soil chemical and microbiological parameters in small (185 m²) and medium (410 m²) gaps, created in mature silver fir (Abies alba Mill) stands (mean height 30 m) in the Calabrian Apennines (Southern Italy), were studied over 2 years. Medium gaps had high soil temperature and photosynthetically active radiation (PAR) transmittance and low soil moisture. Within small gaps we detected a greater amount of organic matter, with respect to under canopy cover sites and medium gaps. Moreover, a different trend of the organic matter between small and medium gaps was observed. In the medium gaps, with respect to under canopy cover sites and small gaps, we found a relatively low content of organic matter, associated to a lower amount of humic acid, which suggested that the organic substrate undergoes a mineralization rather than a humification process. An opposite trend was observed in small gaps, where the increase of organic matter content, associated to an increase of humic acid and microbial biomass, suggested a better humification process. Moreover, in small gaps the highest level of urease and the greatest fluorescein diacetate (FDA) hydrolysis were observed. The different trend of organic matter observed in small and medium gaps may be related to changes in the environmental conditions. PAR transmittance, significantly higher in medium gaps, contributed to increase soil temperature and decrease soil moisture, affecting soil microbial populations and organic matter trend. These results suggest that the creation of small gaps represents the silvicultural practice with minor environmental impact.     

Impacts of fractal features of soil on moisture infiltration capacity of typical stands in Jinyun mountain of Chongqing city

The soil structure was expressed with fractal dimensions of particle size distribution (PSD), aggregate size distribution (ASD), and soil pore size distribution (SPD). The effect of soil fractal features on soil infiltration velocity and process was studied. The result of the fractal feature shows that fractal dimensions of PSD are obviously greater than those of ASD and SPD, and in different soil genetic horizons, the fractal dimension of ASD has the greatest variability, and shows a downtrend on the top-to-bottom genetic horizon. According to the soil infiltration process curve, the infiltration process was divided into three phases: (1) the initial phase (0–5 min), (2) the transition phase (5–30 min), and (3) the stable phase (30–180 min). In the initial phase of infiltration, the soil structure of soil genetic horizon A was the major influencing factor; in the transition phase of infiltration, the pore distribution of soil horizon AB and soil structure of horizon B were the major influencing factors; in the stable phase of infiltration, the soil structure of horizon C was the major influencing factor to the infiltration velocity. Soil infiltration process is influenced comprehensively by soil PSD, ASD, and SPD. In the overall soil water infiltration, the infiltration in shrub forest land was much faster than that in other land uses, and in the initial infiltration phase, arable land soil infiltration was much faster than that in forest land, and in the stable infiltration phase, the infiltration velocity in forest land was faster than that in arable land. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 73–78 [译自: 北京林业大学学报]     

原料表面碱液处理对稻草碎料板力学性能的影响

在实验室条件下探索了稻草原料表面碱液处理对稻草碎料板力学性能的影响.试验表明,处理后的稻草碎料板的内结合强度比处理前有大幅度提高,弯曲弹性模量和静曲强度比处理前则有所下降,但都达到了相关的国家标准;2h吸水厚度膨胀率升高,超过国家标准.因此稻草表面碱液处理提高了稻草原料表面润湿性和胶合强度,但对稻草碎料板的力学性能有影响.     

江西大岗山连栽杉木人工林土壤性质的变化

系统研究了江西大岗山连栽杉木人工林土壤性质变化状况。结果表明：1、2代杉木人工林土壤物理性质相比，不论幼龄林还是中龄林，1代林均明显好于2代林；比较土壤酶活性，各林分也表现出相似的规律，即1代林土壤酶活性较高；而比较两代林土壤化学性质则发现，在幼龄林发育阶段各土壤因于指标变化规律不明显，土壤有机质、土壤氮素等指标反而为2代林较高；但各林分发育至中龄林阶段后则有了较强的规律性，除土壤有效铁和有效铜外，其它所有指标均为2代林较低。     

循环解吸-吸湿处理对尾巨桉胀缩性的影响

采用人工模拟大气湿度变化环境,对尾巨桉木材进行循环解吸-吸湿处理,并测定木材的弦向胀缩性.结果表明:在解吸过程中,初含水率对尾巨桉木材弦向干缩率影响显著;在吸湿过程中,循环处理次数对尾巨桉木材弦向湿胀率影响显著.循环处理可以使尾巨桉木材弦向胀缩率达到稳定的时间缩短,有利于其尺寸稳定.