薪炭林栽培经营技术的研究*

以密植超短轮伐为主的栽培经营试验，在全国１２个省（区）、市建立了１３个试区，２６个试验点，共分５种自然类型。每公顷的造林密度一般为５０００～１００００株；沿海试区１５０００～２００００株。轮伐周期１～２ａ；北方局部地区为３～５ａ。试验林的生物量较一般薪炭林提高３～５倍；西北地区为５～８ｔ／（ｈｍ２·ａ）；东北、华北７～１０ｔ／（ｈｍ２·ａ）；华中地区６～２０ｔ／（ｈｍ２·ａ）；西南１０～２０ｔ／（ｈｍ２·ａ）；南部沿海２０～５０ｔ／（ｈｍ２·ａ）。同时从全国传统薪炭林树种和乡土树种中，筛选出６０个优良树种，供各地选用。     

淹水胁迫对杨树无性系苗期生长及生理的影响

本实验是利用花坛扦插的方法，对３个无性系：ＮＬ－８０１０５杨，Ｉ－６９杨，ＮＬ－８０３５１杨的苗期进行人工淹水处理，处理包括：Ａ—对照，Ｂ—渍，Ｃ—涝。在对３种无性系进行各淹水处理的条件下，通过定期的观测和采样，测定３个无性系在不同处理条件下，其生长、生理指标的变化情况。     

淹水胁迫对杨树无性系苗期生长及生理的影响

本实验是利用花坛扦插的方法，对３个无性系：ＮＬ－８０１０５杨，１－６９杨，ＮＬ－８０３５１杨的苗期进行人工淹水处理，处理包括：Ａ－对照，Ｂ－渍， Ｃ－涝。在对３种无性系进行各淹水处理的条件，通过定期的观测和采样，测定３个性无系在不同处理条件下，其生长，生理指标的变化情况。     

意杨苏柳营养特点与需肥规律研究

试验结果表明：①２年生Ｊ－１９４柳、Ｉ－６９杨不同生长季节养分吸收量大小顺序为Ｎ＞Ｐ＞Ｃａ＞Ｋ＞Ｍｇ，各生长季节养分吸收比例基本一致，Ｊ－１９４柳平均为Ｎ：Ｐ：Ｋ：Ｃａ：Ｍｇ＝１００：９．３１：０．３６０．４２：０．０６，Ｉ－６９杨平均为１００：１１．１８：０．３９：０．０８；②６月份为养分吸收高峰期．当月吸收养分数量占整个生长季节５０％以上，每生长１ｔ带皮柳树材约需Ｎ４．４２５Ｋｇ、Ｐ０．３９６Ｋｇ、Ｋ０．０１３Ｋｇ、Ｃａ０．０１６、Ｍｇ０．００３Ｋｇ，杨树材分别为４．９３７ｋｇ、０．５９３Ｋｇ、０．０１５Ｋｇ、０．０１７Ｋｇ和０．００４Ｋｇ；③营养吸收在各器官分配上以叶子居多，除磷外，依叶＞皮＞材＞嫩枝为序。     

油茶林生物量与养分生物循环的研究

对不同发育期油茶林生物量与养分的生物循环进行了研究。结果表明，从幼龄期至盛果期油茶林生物量逐步积累，盛果期生物量达到１６．１３９ｔ／ｈｍ２，其中经济生物量为１．７９８ｔ／ｈｍ２；不同发育期油茶林分的生产力不同，盛果期油茶林太阳能利用率最高，为０．２％；不同发育期油茶林光合产物在各器官的分配比例不同；不同发育期油茶林系统大量元素（Ｎ、Ｐ、Ｋ、Ｃａ、Ｍｇ）的吸收量、存留量、归还量及输出量不同。并提出了油茶林系统施肥的监界量。     

华南贫瘠丘陵短轮伐期能源、用材林培育技术研究

在水土流失严重的丘陵地，对尾叶按、刚果１２号按、雷林１号按、大叶相思和马占相思等树种的短轮伐期能源、用材林培育技术进行了８年研究。结果表明，在贫瘠立地培育短轮伐期能源、用材林，必须采取集约经营措施，即通过细致整地（坡地带垦，平原台地全垦）、适当施肥（按属树种以Ｎ肥为主，Ｐ、Ｋ肥为辅；相思类树种以Ｐ肥为主，辅以Ｎ、Ｋ肥）、合理密植（经营超短轮伐期能源林，宜采用０．５ｍ×１ｍ密度，轮伐期为２～３年；短轮伐期能源、用材林一般用１ｍ×１ｍ～１ｍ×２ｍ的株行距造林，轮伐期为４～５年；经营短轮伐期用材林，采用１．５ｍ×３ｍ株行距效果较好，植后６～７年采收，以及间种等措施，才能获得速生、高产和短轮伐效果。     

新沂市农田林网杨树生物量的空间结构

本文采用分层切割法和壕沟全挖法对江苏省新沂市农田林网中，４年生主要的杨树无性系（Ｗ－４６杨，Ｉ－６９杨，ＮＬ－８０１０５杨和ＮＬ－８０２０５杨）的地上部分生物量以及根系生物量进行了测定和分析。结果表明，ＮＬ－８０２０５杨不仅平均单株的生物量最大，而且树干的形质优良。因此，在平原农田林网的经营中，选择ＮＬ－８０２０５杨，既可以提高营林的收益，又能够增强林网的防护效果。     

热带薪材林经营技术的研究

根据多年对热带薪材林经营管理及林分采伐更新等的研究，总结了一整套经营技术，包括抹芽定株（保留２～３株／桩萌条）、追肥（复合肥３００ｇ／株）、采收更新的轮伐期（一般４ａ左右，超短轮伐期１．５～２ａ，桉树类与相思类树种的混交林约３年采收相思类树种）、采伐方式（短轮伐期薪材林皆伐、乔薪结合择伐或间伐）、采伐季节（避开雨季，最好时期为冬季，其次为夏季）、伐桩高度（桉树类约１０ｃｍ、相思类约６０ｃｍ高）以及其它与更新相关的林龄、桩径、树种等技术问题。     

雷林1号桉在贫瘠丘陵地造林密度的研究

雷林１号桉在贫瘠丘陵地４种造林密度的林分，经６年的试验结果表明：雷林１号桉林木的生长、产量与造林密度存在着密切相关，其中林木胸径、单株产量及保存率与造林密度呈负相关，单位面积生物量、蓄积量与密度呈正相关，４种密度中０．５ｍ×１．０ｍ密度的林分单位面积生物量最大（８８．３２ｔ／ｈｍ２绝干重，下同），为其他密度林分的２．４倍～５．７倍，适于经营短轮伐期薪材林；１．０ｍ×２．０ｍ的造林密度的小径木占３０％，中径木占６４％，适于经营短轮伐期薪、材两用林；１．５×３．０ｍ密度的中、大径木占８４．５％，适于用材林；２．０ｍ×４．０ｍ密度林木稀疏、产量低，作为经营短轮伐期不宜采用。     

五台山华北落叶松人工林生物生产力与营养元素的积累*

在太行五台山地区，调查华北落叶松人工林林分１６块标准地，并测定了单株平均木各器官生物量及营养元素含量，拟合了华北落叶松林木各器官生物量随年龄变化的ｌｏｇｉｓｔｉｃｓ生长方程。试验表明：华北落叶松立木及林分生物量年平均生长随年龄呈抛物线变化，２４年生时达到高峰，而叶片对干材的净光合同化率１８年生时即达顶峰，约为４００ｇ／ｍ２。１５年生林木各器官主要营养元素总积累量，从大到小顺序为Ｎ、Ｃａ、Ｋ、Ｍｇ、Ｐ，林分每公顷可积累以上五种营养元素的总量是８８８．９１ｋｇ。Ｎ为４０６．８６ｋｇ，其中叶片中Ｎ积累２１４．５６ｋｇ，占总Ｎ积累的５２．７４％；干中Ｎ积累５４．３５ｋｇ，占总Ｎ积累的１３．３６％。１５年生华北落叶松林分，生产１吨干物质即固定Ｎ３．５ｋｇ；而生产１ｍ２木材需固定Ｎ４．６ｋｇ；伐倒１ｍ３木材所消耗的Ｎ仅为０．６１１ｋｇ，占１ｍ３木材需固Ｎ总量的１３．３６％。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

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.     

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.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

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.     

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.