听听绿叶的声音

听听绿叶的声音来自树林的最平凡的声音白桦林里的阵阵掌声红松林里的滚滚涛声听听绿听的声音来自自然的最补素的声音白天她拔动阳光的金弦夜晚她荡起明月的涟漪听听绿叶的声音来自大地的最纯粹的声音岁月对于欢乐的渴望沧桑对于坎坷的收获听听绿叶的声音来自生命的最动人的声音春风起时她的欣喜秋风起时她的羞涩听听绿叶的声音来自心灵的最圣洁的声音青春是她的音符拼搏是她的旋律听听绿叶的声音@白河     

说花

说花□郑道和无论是在繁华的城市，还是在偏远的乡村，人们都能看见花，这是大自然赐给人类的本色美。花的世界赏心悦目，多姿多彩，栽培的，野生的，名贵的，普通的，芳香扑鼻的，鲜艳夺目的，大的，小的，红的，白的……各式各样的花朵，把世界妆扮得如此美丽，给我们的...     

思念

灰色的天空一张欲坠的网晶莹的露珠是云霓的童话美丽的羽毛是蓝天的梦想蜂窝状的城市寻不到鸟声甚至没有一棵小树高耸的天线塔和层叠的脚手架是城市撑开的大手婉啭的鸣唱已锈去黑洞洞的烟囱一把把吞嚼气流中逃散的氧分子从夜晚到早晨城市里的人觉得很累太阳是城市一饼灰黄的蛋糕月亮是城市一只朦胧的睡眼城市的窗前没有蝴蝶城市的阳台只有塑料花微风在尘埃中喘息流水于污浊里洇泣人造的假山没有栖居的绿枝幽暗的沼池难留翩然的鸟影天籁之音被从家园逐出绿树青山已浑然成梦在一个不见落叶的秋天我躺在城市的一隅梦见故乡门前的沙枣树上高高低…     

老师 我们心中永不落的太阳

走过播种的春天,踏着成长的夏天,我们迎来了收获的季节——灿烂的金秋!沉甸甸的种子,经过勤奋者春天的播种、夏天的耕耘,在秋天来临的时候,变成了金灿灿的果实,展示了劳动者的智慧和心血。秋的甘甜,秋的色彩,秋的芬芳,像亮亮的雨丝,洒在收获者的心上。走进果园,百果飘香,到处洋溢着收获的喜悦。红     

河北漳河林场洋槐林地位级曲线

地位级是反映一定树种的立地条件的好坏和林分生产力的指标。地位级的优劣是以一定年龄的林分的平均树高的差异划分的,这种划分方法主要应用于树种单纯的同龄林。在森林经营工作中,对于立地条件的调查以及地位级的划分具有十分重要的意义,因为只有对森林生长的立地质量有一个清楚的了解,才有可能采取一定的营林措施改善立地条件,提高林分     

营林工作者的梦

绿的山,绿的松,绿的小草,绿的风,一切都会走进营林工作者绿色的梦!绿的泉,绿的影,绿的树木,绿的岭,一切都会走进营林工作者绿色的梦…… 他们绿色的梦啊,是希望的梦,希望青山秀水,花艳树俊,色彩缤纷,郁郁葱葱!人们的脸上,都有喜悦的表情,清新的空气回荡在城市乡村……     

林区里那盏盏灯

海岸上灯火通明,那是忙碌的象征;都市里灯红酒绿,那是繁华的见证。有灯的地方往往有人,有人的地方是否有灯?平淡的日子里也有不凡啊,那为绿而时刻痴狂的心,那爱岗敬业忠诚的情,谁说林区里缺少明灯犀利的目光,像明查秋毫的灯,黑恶的手再不敢轻举妄动;闪亮的警徽,是满载荣誉的灯,时刻憧憬奉献的梦;肩上的银星,是担负责任的灯,维护着林区的和谐安宁。攀登陡峭的山峰,额头的汗水化作了奋进的灯;困苦时谁都会流泪,晶莹的泪水化作了坚强的灯;经历了沧桑岁月,留下的脚印是耕耘的灯……看啊平淡中他们点亮了心灯,举着它,奔向充满希望的征程林区里那…     

生活的浪花

运动生命的马达懒惰肥胖的温床卫生健康的卫士肮脏病魔的基地欢乐长寿的妙药忧愁衰老的快车烟酒自杀的凶手生活的浪花@张世和     

红色七月

红色的七月,用随风飘荡的红旗,盛装天地间一片神奇的土地;红色的七月,用热情似火的激情,高唱世纪里一首不朽的赞歌;红色的七月用血与火锻造的铁锤镰刀,铸就了中华民族坚挺的脊梁;红色的七月,用亘古未有的荣光,谱写了一曲东方神话的交响;红色的七月,用举世赞叹的成就,凝聚了一卷     

大雁河我无言的诉说

把童稚的梦幻与歌谣留在了山沟把海的向往与追求搁浅在昨夜的林间一年一年,岭上的花开了又谢一次一次,我心中的潮汐去了再来一如你日夜低吟浅唱的浪漫亲近着我铺遍花朵的心情弯曲出我深深的乡愁摇曳着我漂泊的目光童年的我只要在你身旁看到黄昏木屋上的炊烟轻轻上升内心里就会感到无限的温暖即使做了一件又一件让大人困惑的傻事疲劳也会被巨大的幸福完全淹没潮湃的涛音让我荡气回肠滚烫的热泪一回回漫过我的梦乡有多少可歌可泣的故事因你潮涨让大无畏的英雄气概放射光芒播下情洒下爱的家园更加富强激情燃烧的森林里涓涓细流汇入历史的汪洋我…     

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.     

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.