落叶松腮扁叶蜂自然种群生命表分析

落叶松腮扁叶蜂是兴安落叶松重要食叶害虫，自1998年以来在内蒙古大兴安岭林区成灾，1998—2002年间研究了该虫种群自然消长规律。将落叶松腮扁叶蜂种群按其生长发育顺序划分为卵期、危害幼虫期、滞育幼虫期、蛹期和成虫期5个阶段，把各阶段的作用因子划分为相对独立的状态，根据田间调查及室内实验观察，记录各阶段的存活数，组建了5个世代的生命表，1个平均生命表。分析表明：平均种群趋势指数为4．56。其中危害期幼虫相关系数r值为0．6857，回归系数b值为0．2221，滞育幼虫r值为0．8965，b值为0．6165。滞育幼虫期为落叶松腮扁叶蜂种群生活过程中的关键阶段。滞育幼虫期的自然消亡是影响整个种群动态的关键因素。突然降温等灾害性天气对发生期各虫态影响明显。重要因子分析表明，影响落叶松腮扁叶蜂自然种群的重要因子是天敌、气候、食料等。     

祥云新松叶蜂生物学特性及防治研究

本文对祥云新松叶蜂（ＮｅｏｄｉｐｒｉｏｎｘｉａｎｇｙｕｎｉｃｕｓＸｉａｏｅｔＺｈｏｕ）生物学特性、环境因子、空间分布型及测报作了初步研究，影响害虫发生危害的主要因子是海拔、坡向、林分组成。用空间分布型指数法测定，幼虫在空间呈聚集分布型的负二项分布，聚集均数λ＞２，说明聚集的主要原因是本身的习性（行为）所引起。利用Ｌｗａｏ抽样方程推算出最适抽样数，为林间大面积虫情调查提供理论依据。     

祥云新松叶蜂危害与云南松物候期的关系

通过对祥云新松叶蜂（ＮｅｏｄｉｐｒｉｏｎｘｉａｎｇｙｕｎｉｃｕｓＸｉａｏｅｔＺｈｏｕ）世代和虫期生长发育情况与云南松物候关系的系统观察，初步掌握了该害虫不同危害期与云南松物候的关系。便于用云南松不同的物候期（节令）来测报祥云新松叶蜂的不同虫期和危害状况，为防治这一虫害提供依据     

桦三节叶蜂的发生规律与综合防治

桦三节叶蜂Ａｒｇｅ ｓｉｍｉｌｉｓ Ｖｏｌｌｅｎｈｏｖｅｎ危害桦树。在互助县北山林区一年发生１代，以幼虫危害叶片，总食叶量可达４７．１ｃｍ＾２／头，桦三节叶蜂发生程度主要取决于气候条件，特别是温湿度适宜与否。其次是受越冬蛹茧基数、寄主树种的多寡以及天敌数量的影响，在防治上应采取综合防治措施，如人工消灭越冬蛹茧、营造混交林，保护天敌等方法，以减少幼虫发生量，药剂防治在卵刚孵化后的幼虫期效果最佳。     

祥云新松叶蜂危害与云南松物候期的关系

通过对祥云新松叶蜂世代和虫期生长发育情况与云南松物候关系的系统观察，初步掌握了该害虫不同危害期与云南松物候的关系，便于用云南松不同的物候期来测报实云新松叶蜂的不同虫期和危害状况，为防治这一虫害提供依据。     

桦三节叶蜂的发生规律与综合防治

桦三节叶蜂 Arge similis Vollenhoven危害桦树。在互助县北山林区一年发生 1代 ,以幼虫危害叶片 ,总食叶量可达 47.1 cm2 /头 ,桦三节叶蜂发生程度主要取决于气候条件 ,特别是温湿度适宜与否。其次是受越冬蛹茧基数、寄主树种的多寡以及天敌数量的影响 ,在防治上应采取综合防治措施 ,如人工消灭越冬蛹茧、营造混交林 ,保护天敌等方法 ,以减少幼虫发生量 ,药剂防治在卵刚孵化后的幼虫期效果最佳     

祥云新松叶蜂与会泽新松叶蜂的性信息素评选试验

利用48种人工合成的松叶蜂性信息素单体在云南进行了祥云新松叶蜂和会泽新松叶蜂性信息素的筛测试验,并分别利用二氯甲烷和甲醛提取的祥云新松叶蜂性信息素粗提物,和祥云新松叶蜂处女蜂进行林间诱虫试验。试验结果证明,人工合成的48种松叶蜂性信息素的单体对祥云新松叶蜂和会泽新松叶蜂雄性成虫无引诱效果,需针对祥云新松叶蜂和会泽新松叶蜂重新进行性信息素的结构分析。利用祥云新松叶蜂性信息素二氯甲烷和甲醛粗提物的诱虫效果不如祥云新松叶蜂处女蜂。但其甲醛粗提物和二氯甲烷粗提物均能诱到祥云新松叶蜂的雄虫,说明该甲醛粗提物和二氯甲烷粗提物中含有祥云新松叶蜂性信息素成分,但由于提取的性信息素浓度偏低,故诱虫效果不明显。     

松叶蜂病原真菌的分离鉴定及真菌寄生率的调查

对宁夏、陕西、甘肃的落叶松叶蜂Pristiphora erichsonii、河北的落叶松锉叶蜂P.laricis和落叶松腮扁叶蜂Cephalcia lariciphila、山西靖远松叶蜂Diprion jingyuanensis、陕西松阿扁叶蜂Acantholydaposticalis、云南的祥云新松叶蜂Neodiprion xiangyunicus和南华松叶蜂D.nanhuaensis的幼虫及茧期病原真菌调查统计,并从以上虫茧中分离出真菌13株,初步鉴定球孢白僵菌Beauveria bassiana8株、布氏白僵菌B.brongniatii 4株、青霉属Penicillium sp.1株。选取5株白僵菌以3龄月季叶蜂为试虫进行毒力测试,结果显示1.0×108孢子/mL菌液对试虫有致死作用,校正死亡率69.5%～91%。     

祥云新松叶蜂生物学特性及防治研究

本文对祥云新松叶蜂生物学特性、环境因子、空间分布型及测报作了初步研究，影响害虫发生危害的主要因子是海拔、坡向、林分组成。用空间分布型指数法测定， 空间呈聚集分布型的负二项分布，聚集均数λ〉２，说明聚集的主要原因是本身的习性所引起。利用Ｌｗａｏ抽样方程推算出最适抽样数，为林间大面积虫情调查提供理论依据。     

桦三节叶蜂生物学特性及防治试验

桦三节叶蜂是近几年来在湖北省神农架林区危害红桦的重要害虫。野外调查和室内饲养观察的研究结果表明,桦三节叶蜂在湖北省神农架地区1年发生1代,以幼虫取食叶片,以预蛹在寄主树干皮内茧中越冬;寄生性天敌主要有寄蝇、姬蜂和大腿小蜂3类,天敌对叶蜂茧的寄生率为8%～14%,其中以寄蝇的数量最多。利用3%高渗苯氧威乳油、1.2%烟碱.苦参碱乳油等仿生农药对叶蜂幼虫进行喷烟喷雾具有良好的防效。     

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.     

qPCR quantification of Ophiognomonia clavigignenti‐juglandacearum from infected butternut trees under different release treatments

The use of a molecular assay for quantifying conidia of Ophiognomonia clavigignenti‐juglandacearum, the fungal pathogen responsible of butternut canker, was investigated. Purified DNA from conidia collected on glass fibre filters of a passive rain collectors was quantified using a TaqMan real‐time quantitative polymerase chain reaction (qPCR) assay. The qPCR assay could specifically discriminate the target species from all other North American known species of Ophiognomonia, and it was sensitive enough to repeatedly detect one conidium. A linear relationship between numbers of conidia and qPCR C_t values was determined, and used to assess the sporulation of the pathogen under trees that were released to promote their vigour. In total, 977 samples of field‐captured conidia from 49 trees, at two locations, and from two successive growing seasons were analysed. No significant difference of sporulation was observed under control and release treatments. However, our results demonstrated that qPCR assay was reliable for detecting and quantifying O. clavigignenti‐juglandacearum from environmental samples, which will be useful to assess further control methods for this disease.     

The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia I. Chitemene and Fundikila

Three trials investigating the potential of alley cropping to improve the traditional systems of cultivation, chitemene and fundikila, in the Northern Province of Zambia are described. Flemingia congesta, Tephrosia vogelii, and Sesbania sesban, were grown in association with finger millet, groundnut, cowpea, and maize in various traditional cropping sequences. The indigenous species Tephrosia vogelii and Sesbania sesban were not able to withstand repeated pruning and the long following dry season, and were replaced with Calliandra calothyrsus, and Cassia spectabilis.Over a four year period, there was no benefit by alley cropping with any of the tree species on crop yields, and yields in alley crop treatments even dropped significantly below the control treatments in the fourth year, casting doubt on the potential of alley cropping for sustainable production. There was also no consistent effect on soil chemical characteristics in any of the trials. It was suggested that this lack of beneficial response to alley cropping was due to low tree biomass production low quality of prunings, and an inappropriate cropping sequence. There was no evidence that alley cropping contributed to enhanced nutrient recycling, despite substantial localised pools of soil nutrients, particularly in the chitemene, with which recycling could potentially occur.     

Toxicity of biocide GCSC-BtA on arthropod pests under different temperature conditions

The present research dealt with the toxicity of GCSC-BtA (Germany–China Scientific Cooperation-Bacillus thuringiensis-Abamectin), a new type biocide developed by conjugating a toxin from Bacillus thuringiensis (B.t.) with Abamectin from Streptomyces avermitilis, on arthropod pests under different temperature conditions. The results showed that GCSC-BtA possessed higher toxicity than B.t. crystal, Abamectin or Cypermethrin, with pest mortalities of 97.9, 93.7, 96.4, 82.3 and 96.7% for Tetranychus cinnabarinus (Boisd.) (Acari, Tetranychidae), Frankliniella occidentalis Pergande (Thys., Thripidae), Aphis fabae Scopoli (Hom., Aphididae), Plutella xylostella (L.) (Lep., Plutellidae) and Cameraria ohridella Deschka et Dimić (Lep., Gracillariidae), respectively. Toxicities of GCSC-BtA to T. cinnabarinus and P. xylostella decreased significantly at the older developmental stage with an exception that egg stage had the highest tolerance, in which LC₅₀s of GCSC-BtA were 0.0001, 0.0019 and 0.0708 mg/ml for nymph, adult and egg of T. cinnabarinus, and that 0.0399, 0.2035 and 0.9033 mg/ml for the 2nd instar larvae, 4th instar larvae and egg of P. xylostella, respectively. Also, the biocide was more effective to the lower stage of A. fabae than the higher one with LC₅₀s of 0.0023, 0.0086 and 0.0171 mg/ml against 1st instar nymph, 3rd instar nymph and adult, respectively. In general, toxicity of the new type of biocide was positively related to temperature against all the tested pests, except against T. cinnabarinus, where it was almost similar at the three temperature conditions. GCSC-BtA displayed significantly lower toxicities at 15/20°C than 20/25°C or 25/30°C against F. occidentalis, A. fabae, P. xylostella and C. ohridella. However, no significant difference was found in the toxicities against F. occidentalis, A. fabae and C. ohridella above 20°C, whereas toxicity against P. xylostella increased as temperature raised. Therefore, to achieve higher efficacy in the field, application rate and time should be devised according to these factors.