杉木福建柏混交林效益研究

通过对杉木福建柏混交林中单株生物量组成、土壤团粒组成、土壤孔隙和水分状况的研究分析， 结果表明： 混交林中杉木每ｈｍ ２ 蓄积量是杉木纯林的１６９ 倍， 细根量是杉木纯林的１５ 倍； 与纯林相比， 混交林中０～２０ｃｍ 土层＞ ０２５ｍ ｍ 水稳性团聚体高出９０１％ ； 结构体破坏率低１５８２％ ； 有机质和水解性 Ｎ 含量分别高０２４５％ 和１３１×１０－ ６； 毛管孔隙、非毛管孔隙、总孔隙高００９％ 、０９１％ 、１００％ ， 土壤容重低００５７ｇｃｍ － ３； 最大持水量、最小持水量、毛管持水量分别高３００％ 、３５０％ 、２０４％ ； 混交林４０ｃｍ 土层含水量也比纯林大１５５ｔ·ｈｍ － ２。由于混交林的结构较为合理，能一定程度改善土壤理化性质、提高林分生产力，是一种值得推广的造林模式。     

诱发桃形李煤污病的主导因子和防治方法

诱发桃形李煤污的主导因子是梨园蚧危害，该虫在浙江浦江１年３代，以受精雌成虫越冬。防治方法：２月中下旬，用３￣５度石硫合剂全面喷洒；４月中下旬，５０％杀螟松８００￣１０００倍液喷洒；６月中下旬，５０％甲基托布津０００倍液喷洒；１１月份，５０％久效膦６￣１０倍涂干。     

巨尾桉无性系山地引种造林效果的研究

通过对引进巨尾桉无性系与巨桉、尾叶桉进行山地造林试验３年的研究结果表明，巨尾桉无性系不仅能适宜本地区山地栽培，而且生长快，３年生平均树高１２１ｍ，胸径１２３ｃｍ，单株带皮材积００７２８ｍ３，去皮材积００５７４ｍ３，比尾叶桉分别增长２３５％、２８１％、９２１％和１４０２％，比巨桉分别增长１３１％、１９４％、５６６％和５１５％。它还具有树干通直圆满、树皮较薄、冠径比小、出材率高、丰产性好等特点，可以大面积发展，并总结出栽培上的关键技术。     

双体免充气日光温室的研制与应用

日光温室是在现代加温温室的基础上发展起来的节能型简易园艺栽培设施。由于高跨比小，后坡投影大，透光量不足，有效空间较小，难以满足花卉等高经济性作物大规模工厂化周年高效生产之需求。双体免充气日光温室是在综合多种优化模型分析的基础上提出来的。它在后墙上直接支撑双体免充气可拆式全透光整体曲面结构，其基本参数为跨度５ｍ，脊高２５ｍ，高跨比０５０，后墙高１８ｍ，后坡长１９ｍ，后坡仰角２２°，后坡投影为零，前坡１ｍ处的垂直高度１９ｍ，剖面截面积６４６ｍ２。对照试验表明：双体免充气型无明显的弱光胁地；在不覆草帘的冬季，早晨６时和中午１２时的最高温度分别比对照高２℃和６２℃；夏季５０％遮荫后，室内各点平均温度低于对照３℃；冬季保温效果则更为显著，大于８℃的有效积温分别是鞍山Ⅱ型和室外的１５倍和５３倍；秋、春两季切花月季栽培试验表明，鲜切花的产量和质量也明显高于对照，尤其是早春的盲枝发生率仅为对照的４０％。     

郝家流域针阔带状混交林效应观测

通过对郝家流域内３种混交林（油松×山毛桃、油松×沙棘、樟子松×沙棘）的综合因子进行调查，结果表明，混交林的枯枝落叶量分别是油松纯林的１５倍、３２倍、２７倍；林分总持水量分别是油松纯林的３３倍、８９倍、６４倍。由各树种１０年生长进程可以看出，樟子松×沙棘、油松×山毛桃的混交效果较好。     

龙眼扦插育苗及丰产栽培技术研究

采用文中所介绍的技术，龙眼扦插４０天后即产生愈伤组织，愈合率达８６６％；６０～９０天大量生根，生根率达８７２％，成活率达７４５％；９０天后即可进行苗地移栽，成活率达９０５％。１年生苗高６０～１５０ｃｍ，地径０６～１５ｃｍ，此时即可出圃定植。２～３年挂果，４年进入丰产期，丰产效果显著。     

氧对亚硫酸盐制浆废液戊糖、己糖同步酒精发酵的影响

研究了氧对休哈塔假丝酵母Ｒ的戊糖酒精发酵的影响。休哈塔假丝酵母Ｒ的戊糖酒精发酵需在“限制性供氧”条件下进行，溶解氧浓度在０９～１１ｍｇ／Ｌ时，木糖利用率和酒精得率分别为８３８％～９３５％和８８４％～９１２％；在１５Ｌ发酵罐中发酵富含戊糖的亚硫酸盐制浆废液３２ｈ，糖利用率和酒精得率分别达９２５％和８５０％，酵母细胞吸氧速率为１２４～１．４８ｍｍｏｌ／Ｌ·ｈ，溶氧系数ＫＬａ值１４７５～１８００ｈ－１；当通风量为４ｍ３／ｈ时，在５ｍ３发酵罐中发酵还原物为２２９０ｇ／Ｌ的亚硫酸盐制浆废液２２ｈ，还原物降至５９ｇ／Ｌ，醪液酒精浓度达０７４％（ｖ／ｖ），通风量过高或过低均导致酒精得率的下降。     

蓝桉、直干桉工业原料林经济效果分析

按经营纤维用材为主，合理利用桉叶，主伐后实行萌芽更新的经营模式营造蓝桉、直干桉工业原料林，第１个实生林轮伐期净现值为５０５９元／ｈｍ２，内部收益率为３５６％，费用效益比为１５９。经营３个轮伐周期，其净现值为第１个实生林轮伐期的２３倍，内部收益率比第１个实生林轮伐期提高４２％，费用效益比提高２０８％。经济效益显著，抗风险能力强，是建立短期轮伐工业原料林的较佳选择。     

6HY-25型烟雾机弥雾载药防治杨尺蛾试验初报

杨尺蛾是杨树主要食叶害虫之一。在树龄６～１０年、树高１６～２１ｍ、郁闭度０４～０６的杨树林内，选用６ＨＹ—２５型烟雾机（江苏省南通市广大集团生产）弥雾载药，于杨尺蛾２龄幼虫高峰期喷５％高效氯氰菊酯乳油、５０％甲胺磷乳油、柴油（按１∶０５∶１２混合）复配剂１３４０～１５４５ｇ／ｈｍ２，喷后第３天平均每叶簇有活虫０１头，比喷药前减少３４头，杀虫率９７２％。并具有简便易行、工效高、成本低的优点。     

高得率浆废水生物净化处理系统研究(Ⅱ)——山杨CTMP、APMP废水活性污泥法处理

研究山杨高得率浆（ＣＴＭＰ、ＡＰＭＰ）废水在实验室用活性污泥法连续处理的净化效果。结果表明：（１）两种废水用活性污泥法处理可得到良好的净化效果。ＣＴＭＰ废水在全部水力停留时间（ＨＲＴ＝１０～５６ｈ）内，ＣＯＤ负荷量在２１８～１２９ｋｇ／ｍ３·ｄ时，ＣＯＤｃｒ、ＢＯＤ５去除率分别为６５９％～８１０％（平均７４６％）和９５５％～９８１％（平均９６８％）；ＡＰＭＰ废水在ＨＲＴ为１０～４６ｈ，ＣＯＤ负荷量为３４７～１６１２ｋｇ／ｍ３·ｄ时，ＣＯＤｃｒ、ＢＯＤ５去除率分别为８４０％～８５６％（平均８４９％）和９８０％～９８９０％（平均９８６％）；（２）在试验采用的全部水力停留时间内，通过处理产生的污泥的ＳＶＩ（污泥指数）均低于１５０ｍＬ／ｇ，污泥的沉降性能良好，在整个试验中，未发现污泥膨胀现象；（３）活性污泥法操作管理简单、方便，对废水的适应性强     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.