半枫荷与杉木树种混交造林试验初报

针对半枫荷与杉木混交、半枫荷纯林、杉木纯林进行了造林试验,结果表明:混交林中7年生半枫荷的胸径、树高、蓄积量生长量指标明显高于同龄林半枫荷纯林的胸径、树高、蓄积量生长量指标;混交林中7年生杉木的胸径、树高、蓄积量生长量指标明显高于同龄林杉木纯林的胸径、树高、蓄积量生长量指标。混交林的半枫荷平均胸径为8.14cm,平均树高为7.19m,单株平均蓄积量0.0219m~3,保存率达89.3%,分别比纯林高出1.48cm,1.46m,0.0091m~3,2.2%;混交林的杉木平均胸径为8.84cm,平均树高为6.43m,单株平均蓄积量0.024m~3,保存率达93.7%,分别比纯林高出1.19cm,1.11m,0.0073m~3,1%。半枫荷与杉木混交,林分郁闭度达到0.90。分别高出杉木纯林0.1,高出半枫荷纯林0.2。经分析对比说明,无论是纯林还是混交林,坡位对林木胸径、树高、蓄积量的生长量指标均具有极显著影响,以下坡位生长最快,中坡位次之,上坡位最慢。     

不同造林密度对钟萼木生长的影响

对不同造林密度10年生的钟萼木的生长进行了调查,结果表明:不同造林密度对钟萼木的保存率无显著影响,对胸径、树高生长具有显著影响;试验总结出营造钟萼木纯林的合理初植密度为2425株/hm2,平均保存率、平均胸径、平均树高分别达87%、5.2cm、4.3cm,试验结果可为钟萼木人工林培育提供技术参考。     

杉木与红锥不同造林方式生长效果研究

采用不同造林方式,研究杉木、红锥林分生长状况。结果表明:造林4a后,杉木与红锥混交林的生长效果优于杉木、红锥纯林,与纯林相比,混交林杉木、红锥平均树高分别比纯林提高26.45%、21.56%,平均地径分别比纯林提高6.88%、10.6%,平均树冠分别增加6.89%、10%。4a生杉木与红锥混交林年均树高生长0.98m、地径生长1.67cm、树冠增加0.8m,达到速生丰产林水平。     

杉木枫香不同混交方法造林初期效果分析

试验采用杉木、枫香实生苗进行带状混交、块状混交、株间混交造林及营造纯林,通过对试验地4a生的杉木、枫香幼林生长量进行调查,结果表明:带状混交的杉木、枫香的生长效果最好,其中杉木的平均胸径达5.7cm,分别比块状混交、株间混交高出1.8%、9.6%,比杉木纯林高出23.9%;平均树高达4.0m,分别比块状混交、株间混交高出2.6%、8.1%,比杉木纯林高出14.3%;枫香的平均胸径达6.3cm,分别比块状混交、株间混交高出6.8%、18.9%,比枫香纯林高出34.0%;平均树高达6.2m,分别比块状混交、株间混交高出17.0%、37.8%,比枫香纯林高出44.2%;杉木、枫香的总保存株数达2955株/hm~2,比块状混交、株间混交高出0.5%、0.8%,比杉木纯林高出2.1%,比枫香纯林高出3.7%;总蓄积量达19.332m~3/hm~2,比块状混交、株间混交高出9.4%、25.9%,比杉木纯林高出63.0%,比枫香纯林高出57.7%。     

杉木皆伐更新杉木木荷混交林生长效益分析

于2021年,在福建省永安国有林场对杉木人工林(1代)皆伐后更新的32年生的杉荷混交林和杉木纯林(2代)的生长状况进行调查分析。结果表明：32年生的8杉2荷人工混交林中,杉木平均树高20.1 m、胸径25.8 cm、单株立木材积0.4727 m³,林分蓄积量425.43 m³·hm^-2,达到杉木最适宜区Ⅰ级立地速生丰产林大径材生长量指标;比前茬相同林龄的杉木纯林平均树高(20.5 m)、平均胸径(26.1 cm)和单株立木材积(0.4923 m³),分别减少2.0%、1.1%和4.0%,但二者间差异不显著;比连栽杉木(2代)纯林平均树高(18.0 m)、平均胸径(23.6 cm)、单株立木材积(0.3628 m³)和林分蓄积量(392.89 m³·hm^-2),分别增加11.7%、9.3%、30.3%和8.3%,二者间差异达极显著;杉木大径木占51.7%,比杉木纯林(2代)增加17.0%。表明杉木皆伐更新杉荷混交林有利于杉木大径材培育,...     

杉木与红豆树混交造林技术试验

杉木与红豆树纯林、混交造林试验,采用不同造林密度,林木生长经过8年的经营管理,通过调查可知:8年生的杉木与红豆树纯林林木生长量分别平均树高为6.7m、5.6m,胸径粗为7.1cm、6.0cm,树冠大为4.2m、4.6m,郁闭大为0.7、0.8.8年生的杉木与红豆树混交林林木生长量分别平均树高为7.5m、6.3m,胸径为7.8cm、6.6cm,树冠为4.5m、4.8m,郁闭度为0.9.杉木与红豆树混交林比纯林的平均分别树高大10.4%、3.2%,胸径粗1.2%、20%,树冠大11.9%、2.2%,郁闭度大28.5%、12.5%.     

坡位对杉木米老排混交林生长的影响

选择福建省建阳范桥国有林场不同坡位18年生杉木米老排混交林,开展生长及生物量调查。结果表明:坡位对杉木米老排混交林生长量及生物量有较大影响,杉木、米老排生长量、生物量的高低顺序均为:下坡>中坡>上坡。下坡杉木米老排混交林的平均胸径、平均树高、蓄积量、乔木层生物量分别为16.5 cm、13.2 m、207.4416 m3·hm-2、161.55 t·hm-2,分别比上坡杉木米老排混交林高出34.1%、25.7%、111.3%、89.0%。杉木米老排混交林生长量、生物量高于杉木纯林。     

萌芽杉木与杂交马褂木混交效果分析

采用标准地调查、树干解析等方法对福建省明溪县城关乡大坪村8年生的萌芽杉木纯林及萌芽杉木、杂交马褂木混交林的树高、胸径、蓄积量等进行对比分析,结果表明:混交林萌芽杉木的平均胸径、树高、单株材积、林分蓄积量和优势木树高分别比杉木纯林高12.8%、10.7%、35.0%、34.4%和11.4%;混交林杂交马褂木的平均胸径、树高、单株材积、林分蓄积量和优势木树高分别比杉木纯林的人工实生杉木高67.6%、61.5%、323.1%、319.6%和77.6%;混交林的林分总蓄积比杉木纯林高103.4%;混交林林分地上部分总生物量比杉木纯林高85.9%;混交林杂交马褂木与萌芽杉木除在4~6m高度处存在种间竞争外,其他空间分布合理,有效提高了林地生产力。     

广西维都林场杉木红椎混交林早期生长对比试验

在广西国有维都林场进行红椎纯林、杉木纯林、“红椎+杉木”混交林(5∶5行状混交)早期生长量对比试验,结果表明,杉木纯林、红椎纯林、“杉木+红椎”混交林的成活率、保存率皆超84%以上,不同造林模式对树种成活率、保存率无显著影响;混交林杉木的平均树高较纯林增长13.11%,平均胸径增长9.13%;混交林红椎的平均树高、平均胸径分别比纯林增长2.03%、36.65%;混交林中红椎、杉木生长值皆超过相应树种的广西壮族自治区地方标准规定的生长指标。采取杉木与阔叶树红椎混交造林,对杉木、红椎的早期生长量均有促进作用。     

杉木和枫香混交对杉木生长及土壤肥力的影响

本文研究了杉木和枫香混交经营5 a后对杉木生长和林分土壤肥力的影响。结果表明：虽然杉木与枫香混交造林降低了杉木的存活率,保存率仅为87.0%,但混交林中杉木和枫香的平均胸径、树高均显著大于杉木纯林,其中杉木的平均树高、胸径分别为4.68 m、5.41 cm,分别是杉木纯林的1.20和1.19倍,说明杉木与枫香混交经营促进了杉木的树体生长;混交林土壤中的有机碳累积量大于纯林,且土壤的养分指标如全氮、全磷、水解氮、速效磷的含量均比杉木纯林高,阳离子交换量（CEC）和盐基离子含量分别比杉木纯林增加了17.37%和18.11%,说明混交林在提高土壤固碳能力的同时,也使林地的肥力状况得到一定程度的改善。     

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.     

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。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.