强化火源管理 严防森林火灾：永平县生产用火管理有新招

位于云南省大理州西部的永平县是云南省的重点林区之一,同时又是云南省森林火灾多发县之一。据统计,１９５３～１９９０年,全县发生森林火灾３８４５次,年均１０１次;受害森林面积１６．３４万ｈｍ２,年均０．４３万ｈｍ２。进入“八五”期后,各级领导加强了对森林...     

特效生物杀虫剂——“苏力精”林间防治马尾松毛虫研究

使用不同剂型、不同用量（浓度）的苏力精防治１、２代马尾松毛虫幼虫试验结果表明，１２００ｍｌ／ｈｍ２悬浮剂防治效果９０．１％～９０．４％；７５０ｇ／ｈｍ２可湿性粉剂防治效果９５．０％～９６．４％，１８７５ｇ／ｈｍ２粉剂喷粉防治效果７９．２％～８６．５％，而且残存害虫化蛹后继续死亡，成虫产卵量显著减少，对松毛虫天敌无显著不良影响。使用７５０ｇ／ｈｍ２可湿性粉剂在松毛虫卵期防治，防治效果８１．５％～８３．２％。     

论哲盟松毛虫综合管理的战略

论哲盟松毛虫综合管理的战略闫伟勇（哲里木盟森林病虫害防治站松毛虫属鳞翅目枯叶蛾科，是松树的毁灭性食叶害虫。由于经营不当，生态系统遭到严重破坏，使松毛虫危害日趋严重。我盟南部山区油松林年发生面积１．７万ｈｍ２左右，且落叶松毛虫、油松毛虫、赤松毛虫相伴发...     

黄岩市马尾松毛虫综合防治技术研究

马尾松毛虫是我市危害最严重的森林害虫，年发生量６０００余ｈｍ２，于１９８９年开展了对该虫的综合防治技术研究，经６年的工作，加强了测报队伍建设，提高了测报质量，开展了以营林为基础，采用生物防治、鸟类招引、点灯诱杀及推广应用新农药等综合防治措施，使防治总面积达６８８２ｈｍ２，有效地控制了松毛虫的危害，６年来共挽回经济损失１５５．２万元，为综防工程建设费用（总支出１５．２３万元）的９．１９倍。     

广西马尾松毛虫发生类型区的划分与应用

广西马尾松毛虫发生类型区的划分与应用庞正轰，杨秀好，文凤芝梁修达（区森防站）（柳州地区森防站）马尾松毛虫是广西最重要的森林大害虫。１９８０年至１９９５年，年均发生面积２０万ｈｍ２以上，直接经济损失５０００万元以上。马尾松毛虫灾害已成为我区巩固造林绿化...     

应用文山松毛虫质型多角体病毒大面积防治坝心林区文山松毛虫试？…

应用文山松毛虫质型多角体病毒（ＣＰＶ），于１９９１年、１９９２年、１９９４年，在献词主林区防治文山松毛虫，达１７２９．２７ｈｍ＾２，松毛虫开遍率分别为９０．７８％、８５．７％、８９．６％，示范林内固定样地的松毛虫校正死亡率达９３．２９％，有虫株率由９８．６％下降到２７．６６％，虫口密度由１４．２４头／株下降到０．６１８头／株。病毒能流行传染持续控制松毛虫的危害最佳防治虫龄是３～５龄，林间空气湿润的     

特效生物杀虫剂—“苏力精”林间防治马尾松毛虫研究

使用不同剂型，不同用量的苏力精防治１，２代马尾松毛虫幼虫试验结果表明，１２００ｍｌ／ｈｍ＾２悬浮剂防治效果９０．１％－９０．４％；７５０ｇ／ｈｍ＾２可湿性粉剂防治效果９５．０％－９６．４％，１８７５ｇ／ｈｍ＾２粉剂喷粉防治效果７９．２％－８６．５％，而且残存害虫化蛹后继续死亡，成虫产卵量显著减少，对松毛虫天敌无显著不良影响。     

推行林业股份合作制 加快绿化“灭荒”速度

推行林业股份合作制加快绿化“灭荒”速度房西文（陕西省林业厅，陕西西安７１００８２）“七五”以来。我省林业生产建设有了长足发展。在１９８９～１９９４年的６年中，全省有林地由４９３．３３万ｈｍ２增加到５９３．３３万ｈｍ２，年均增加近２０万ｈｍ２，覆盖率相...     

海南岛清澜港红树林垂直结构与演变动态规律*

清澜港的红树林在保护较好的条件下具有乔灌两层，乔木层高４～８ｍ，灌木层高０．４～１．２ｍ。上层立木地上部分生物量垂直分布随树体部位增高而减少，０～２ｍ占５０％，２～４ｍ占４０．３％，４ｍ以上占９．７％。乔木群落被破坏后，面积锐减，２７ａ减少１６１１ｈｍ２，且形成仅有单层结构的灌丛，其生物量和生产力很低，分别为９．６～１４．３ｔ／ｈｍ２和１．１～２．０ｔ／（ｈｍ２·ａ）。本项研究测定了木榄林的生物量和净生产量分别为９１．５ｔ／ｈｍ２和４．７ｔ／（ｈｍ２·ａ），预测以后第６年的生物量和年净生产量将是３５０．７ｔ／ｈｍ２和１３．５ｔ／（ｈｍ２·ａ），为红树林造林和经营提供了理论依据。     

毛竹林环境因子与一字竹笋象危害关系的研究

１９９１～１９９３年调查发现，一字竹笋象在龙游县年发生面积近０．５４万ｈｍ２，为毛竹林的一种主要笋期害虫，该虫的发生与危害主要在海拔６００ｍ以下的竹林内，阳坡为害重于阴坡，花年竹林明显重于大小年竹林，对竹林垦复可减轻为害程度。     

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.     

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.     

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.     

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.