Ecological Benefit of Reforestation in a Severely Degraded Red Soil Region

Guifeng, Yiyang County, belongs to a seriously degraded red soil region. In 1991, Pinus elliottii and Lespedaza spp. were the species selected for the establishment of a mixed forest in the area. The results of an investigation of the soil system in a 12-year-old forest indicated the following: (1) Organic matter and total nitrogen of the forest soil to a depth of 40 cm were 88.0 and 36.0% higher, respectively, than those of a control plot; total phosphorus and available phosphorus were 40.9 and 22.3% higher than those of the control; available potassium contents were 8.13% lower than those of the control. (2) Soil aeration and the soil air regime improved. (3) Proteinase, catalase, and urease in the forest soil to a depth of 40 cm were usually higher than those in the control plot and decreased with soil depth. Translated from Acta Agriculturae Universitatis Jiangxiensis, 2005, 27(1) (in Chinese)     

Altitudinal patterns of the flora of seed plants of Dawei Mountain in Yunnan Province, south China

Altitudinal gradient incorporates multiple resource gradients, which vary continuously in different fashions. It is important to study the mountain floristic patterns along altitudinal gradients, which reveal the regular pattern of the flora along the environmental gradients, the changing trend of biodiversity patterns along the altitudinal gradient, and relevance of biological fitness. To explore the compositional characteristics and ecological significance of floristic patterns along altitudinal gradient in China National Nature Reserve of Dawei Mountain in the southeast of Yunnan Province, field investigations have been made to the flora along the two routes of the southwest slope and the northeast slope of the said reserve, including a vertical vegetation transect. Meanwhile, further investigations have also been made to the flora of Dawei Mountain, which has been accounted for in the literature, as Flora Yunnan, The Seed Plant in Yunnan, and so on. The structural characteristics of the flora and the altitudinal distribution pattern of its floristic components were analyzed. By applying systematic cluster analysis, the altitudinal position of the dividing line of floristic changes along altitudinal gradient was detected, and the effects of the montane climate on the vertical variation of floristic composition were studied. Conclusions were put forward. This paper can be summarized as follows: (1) The obvious boundary that differentiates tropical floristic elements is located at the altitude of approximately 1,500 m; it is reasonable to stipulate the boundary line between tropical rain forests and the evergreen broad-leaved forests. (2) The vertical vegetation spectrum made by cluster analysis shows that humid rain forests are below 700 m a.s.l, montane rain forests are between 700 and 1,500 m, monsoon evergreen broad-leaved forests are between 1,300 and 1,800 m, and montane mossy evergreen broad-leaved forests are above 1,800 m a.s.l. Nonrepresentative montane mossy dwarf forests (above 2,100 m) in the area are distributed in windward sides and in barren land on the mountain slopes. __________ Translated from Acta Phytoecologica Sinica, 2005, 29(6): 894–900 [译自: 植物生态学报]     

Deposition patterns in bulk precipitation and throughfall in a subtropical mixed forest in central-south China

The chemistry and deposition pattern in bulk precipitation andthroughfall (TF) were examined and evaluated based on the 3-yearobservations in Shaoshan subtropical deciduous-conifer mixedforest in central-south China. The TF chemistry was notablychanged when passing through canopies, which probably was attributedto the dry deposition (DD) on leaf surface and the canopy exchanges.Base cations' (Ca²⁺, Mg²⁺ and K⁺) fluxes were significantlyenriched in TF, in particular for K⁺. The annual K⁺ canopy exchangewas 12 times larger than DD, and canopy exchange of Ca²⁺, Mg²⁺and K⁺ was four times as high as the DD. The canopy exchangeof base cations in association with weak acid accounted for28.4 per cent of total leached base cations, which was one ofthe important factors to modify the TF chemistry.     

杉木连栽林地土壤微生物区系及其生化特性和理化性质的研究

选择立地坏境条件相同的杉木连栽与头栽林地，进行土壤微生物，酶活性及理化性质的分析。研究表明，杉木连栽林地土壤微生物总数下降２３．３５％，其中细菌、放线菌分别下降２４．７９％和３４．０４％，真菌增加１０．３９％微生物主要生理类群氨化细菌、纤维素分解菌、好气固氮菌、微嗜氮菌分别下降３６．６０％、１４．２４％、５６．５６％和２５．８１％，厌气固氮菌增加４６．１５％．连栽林地土壤的脲酶、转化酶、过氧化氢酶的活性明显低于头栽土壤、多酚氧化酶则相反。在０－４０ｃｍ土层中．同于连栽引起土壤容重增加２．５９％、毛管孔隙、毛管含水量、田间持水量和自然含水量分别下降８．４６％、１１．０４％、１１．７８％和７．０８％，土壤有机质、Ｎ、Ｐ全量分别下降１６．６１％、１２．７５％和２１．４９％．Ｎ、Ｐ、Ｋ速效养分含量分别下降２０．０８％、８．７８％和２４．８５％．因而提出营造混交林，发展林下植被，停止或减少炼山和全垦以及增加肥料投入等技术对策。以防止连栽引起的地力衰退。     

菇木林育苗造林试验初报

采用多年多点进行菇木多树种育苗造林试验，３年来共育苗１１ｈｍ２，营造试验林２０．８ｈｍ２，示范林６８．５ｈｍ２，树种１９个。试验结果表明，选用水稻田育苗，通过间苗补植等措施，使合格苗达８０％以上；选择山坡谷地的土层深厚、肥沃湿润地段造林，其成活率达８５．８％～９８．３％２年生桤木幼树，平均树高３．９３ｍ，平均地径４．１ｃｍ。初步看出桤木、杜英、马褂木是良好的速生菇木树种。     

公路桥梁中无粘结部分预应力混凝土梁计算模式的采用

计算UPPC梁(板)的抗弯强度,关键是确定构件在极限承裁能力时无粘结预应力筋的极限应力值。在UPPC梁的设计中,应根据结构的断面形式、受力状态采用不同的计算方法加以比较,以增加UPPC结构设计的准确性及合理性。同时建议结合现行“公桥规”中对有粘结预应力混凝土结构的计算原理与方法较全面、系统地研究UPPC梁桥的设计原理,并给出相应的实用计算方法和公式,从而为UPPC桥梁设计和“公桥规”的完善提供有价值的参考。     

活性炭负载磷钨酸催化α-蒎烯的异构化反应

研究了磷钨酸、活性炭负载磷钨酸催化α－蒎烯的异构化反应，考察了反应条件对α－蒎烯转化率和产物选择性的影响。结果表明：活性炭负载磷钨酸催化α－蒎烯的异构化反应具有反应温度低、催化活性高、莰烯和荣烯选择性高等优点，将磷钨酸负载于活性炭载体上以后，其催化活性和稳定性增大，并可重复使用。     

Impacts of mixed litter decomposition from <Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> and other tree species on C loss and nutrient release in the Loess Plateau of China

The productivity of Robinia pseudoacacia (R.p.) pure forest usually declines at the late growth stage, and reforming it into mixed forests could be a promising way to resolve this problem. When choosing a suitable tree species that can be mixed with R.p., the interspecific relationship is an important issue. Therefore, we gathered the autumn litter fall from R.p. and 10 other species from the Loess Plateau of China were mixed in dual species litterbags (R.p. + each other species) and buried them in soil for a 345 days lab decay incubation. We measured the litter mass loss and nutrient contents to determine whether the nutrient release was affected by mixed species litter decomposition. The impacts of mixed litter decomposition on macro-elements release were more obvious than on micro-elements. The litters with similar substrate quality might show variable impacts on nutrients release in mixed decomposition. The C loss and release of nutrient was improved by descending order when R.p. litter was mixed with Hippophae rhamnoides, Ulmus pumila, Populus simonii, Larix principis-rupprechtii and Quercus liaotungensis (Q.l.). But, except for Q.l., only the other species were recommended as suitable mix-plants for R.p. since promoting a high turnover of the nutrient in the litter compartment and a rapid availability for tree.     

密山至兴凯湖旅游公路冬季土方施工

本文叙述了冬季土方施工的方法、步骤和要点。     

山东省高速公路绿化对空气的净化效果研究

采用测定SO2、NO2和CO2气体含量的方法,研究了山东省主要高速公路路侧绿化带,互通立交区、入口匝道区和服务区绿地对空气的净化效果。测定结果表明,路侧绿化带对SO2有较明显的净化作用,互通立交区、入口匝道区和服务区的绿化对SO2和NO2均有较好的吸收净化作用,而高速路绿化对CO2含量的影响则较小。