城市道路网信息管理系统研究

针对国内城市交通规划缺乏完整的道路信息资料 ,提出了如何利用功能完善的EMME/2交通规划软件结合中国的交通特性 ,进行城市路网信息资料的获取 ,并提出相应的数据库记录规定 ,据此研制开发了城市道路网信息管理系统。     

Relationship between effective solar radiation and sap flow process during an entire growing season in Western Mountains of Beijing

In order to explore the relationship between the time processes of solar radiation and sap flow, sap flow velocity (SFV) of Platycladus orientalis and Pinus tabulaeformis, effective solar radiation (ESR) and other environmental factors were synchronously monitored for one year in the Beijing Western Mountains by using a thermal dissipation probe (TDP) system and an automatic weather station. Results showed significant differences between changes in diurnal characteristics of ESR and sap flow in sunny days during three seasons. Starting times of sap flow occurred generally 1.5–3 hours later than those of solar radiation and there were small differences between Platycladus orientalis and Pinus tabulaeformis. But peak times and stopping times of sap flow varied con-siderably with large contrasts in ESR. The duration of sap flow showed clear differences among the seasons owing to the variable rhythms of climate factors in Beijing. Fluctuation amplitude in the duration of sap flow remained relatively stable during the autumn but changed greatly during spring and summer. Changes in diurnal sap flow velocity of both Platycladus orientalis and Pinus tabu-laeformis were about 0–3 hours later than those of ESR but with the same configuration. The start of sap flow was mainly induced by the sudden intensification of ESR (sunrise effect). Seasonal models of SFV indicated that a cubic equation had the best fit. It was more practical to simulate seasonal water consumption models of trees with ESR. In further investigations, these models should be optimized.     

论节能式炉气体木材干燥室的设计

本文讨论了节能式炉气干燥室设计的一些技术问题，如提高自生风引力增强通风；多种传热方式并用，增强传热，降低热损失的途径等，以达到节能降耗、快速干燥的目的。     

蒟蒻薯净光合速率与蒸腾速率日变化

在晴天条件下,研究了蒟蒻薯(Tacca chantrieri)生长期的净光合速率、蒸腾速率、气孔导度、水分利用效率。结果表明,蒟蒻薯净光合速率日变化呈双峰曲线,光合"午休"现象明显;气孔导度的降低会引起蒸腾速率的降低;蒸腾速率日变化也呈双峰曲线,平均蒸腾速率为0.186mmol.m-2.s-1,平均水分利用率为12.071μmol CO2/mmol H2O。     

Differential overstory leaf flushing contributes to the formation of a patchy understory

Understory individuals were found to form patches in a 100-year-old deciduous broad-leaved forest. The closed forest canopy was uniform, and so the light conditions at various locations across the forest floor differed little after the leaf flush of the overstory. To explain the distribution pattern in the understory, a hypothesis was proposed: in spring, the forest floor is divided into patches according to the timing of leaf flush of the overstory individuals, and the light conditions are more favorable for understory plants under the crowns of trees with later-flushing leaves. In the plot, three groups of early, intermediate, and late, were recognized in the overstory concerning the timing of leaf flush. As for the start of leaf flush, a difference of 31.6 days was recognized among tree species, and for the end of leaf flush, a difference of 40.3 days. In the spring of 1998, the relative photosynthetic-photon-flux density under an intensively studiedCastanea crenata tree (late-flushing species) usually showed higher values than that under a similarly studiedAcer mono tree (early-flushing species). Analysis of the spatial-distribution pattern using Morisita’s1δ index revealed that the understory community had an aggregated distribution. In the overstory, the late- and the intermediate-flushing-species groups showed aggregated distributions, while the early-flushing-species group showed random distribution. Spatial correlation between the understory and the overstory was analyzed by using Morisita’sRδ index. The distribution of whole understory community spatially co-occurred with that of the late-flushing-species group of the overstory. In contrast, the understory community was less developed below the members of the early-flushing-species group of the overstory. We consider that the data presented here support our hypothesis, and we suggest that the growth and survival of understory individuals were promoted in the places receiving light for long periods in spring.     

Cost minimization through the use of taungya system in pulpwood plantation establishment

The costs and benefits of the use of three labour alternatives: direct permanent, direct casual and taungya labour in Gmelina arborea pulpwood plantation establishment in Nigeria were investigated. Results show that cost per hectare is lowest with taungya labour and highest with permanent labour with savings in cost of as much as 30% and 47% by taungya labour over casual and permanent labour respectively. The net present value per hectare of investment is highest when taungya labour is used and lowest and negative with permanent labour. Also, the internal rate of return of investment is highest with taungya labour and lowest with permanent labour. The net present values and internal rates of return for Gmelina plantations calculated for the three pulp and paper mills in Nigeria show the same trend in favour of taungya labour.     

谈地面辐射采暖方式的应用

本文阐述了地面辐射采暖的特点及辐射采暖的构造,施工方法及注意事项。     

四川盆地浅丘陵区农林复合系统内部天空散射辐射分布特性理论分析

根据四川盆地浅丘区农林复合系统特点,从理论上分析了该系统内天空散射辐射令布特征。提出了在林带和地形(坡度变化)的双重影响下的林带间平均相对辐照成分布特征,为农林复合系统的设计提供了依据;除林带本身产生“光胁地”外,地形变化即坡度的增加,叶“光胁地”效应有增强作用,对其范围有扩大作用。     

不同立地长白落叶松净光合特征的研究

本文通过对不同立地、不同年龄段长白落叶松净光合速率与呼吸速率的测定 ,测定出了长白落叶松净光合速率和呼吸速率 ,以及长白落叶松净光合速率的日进程与季节进程。通过对比试验测定 ,得出长白落叶松以 10年生净同化率最高 ,值为 :0 .30 51mgCO2 m- 2 s- 1,四大林场中以哈尔滨林场的长白落叶松净同化率最高 ,值为 0 .1335mgCO2 m- 2 s- 1。长白落叶松CO2 补偿点为 130vpm ,光呼吸值为 4 0vpm     

Dry matter production and nutrient cycling in agroforestry systems of mandarin grown in association with Albizia and mixed tree species

A study on dry matter production and nutrient cycling in agroforestry systems of mandarin grown in association with N₂-fixing Albizia and mixed tree species (non-N₂-fixing) was carried out in the Sikkim Himalaya. A site with Albizia was referred asAlbizia-mandarin stand and the other site with mixed tree species as mandarin stand. The stand total biomass, net primary productivity and mandarin fruit production was higher under the influence of Albizia. Agronomic yield of crops remained nearly the same in both the stands. Nitrogen and phosphorus concentrations of different components of Albizia were higher than those of mixed tree species, whereas their back translocation from leaf to branch before abscission was lower inAlbizia. The mandarin-based agroforestry is a highly nutrient-exhaustive system evaluated in terms of nutrient exit through the removal of agronomic yield. This system, under the influence of Albizia, was more productive with faster rates of nutrient cycling. Nutrient use efficiency increased under the influence of Albizia, in contrary to the hypothesis that efficiency should decrease with increasing rate of uptake. The poor nutrient conservation of Albizia, and malleability of nutrient cycling under its influence make it an excellent association which promotes higher availability and faster cycling of nutrients.Albizia should be utilised more extensively in the management of mandarin-based agroforestry systems.