森工企业年伐量计算方法的探讨

确定合理的年伐量是实现森林永续利用的关键。文内介绍了面积法、蓄积量法和生长量法三种计算森林年伐量的方法。     

红脂大小蠹饲养观察研究

本文对红脂大小蠹饲养观察中的“伐桩罩笼法”、“试管法”、“玻璃夹板法”、“培养皿法”、“段木法”进行了研究。结果表明:“伐桩罩笼法”、“段木法”观察各虫态发生期及年发生代数,效果较好,观察卵、幼虫、蛹的发育过程及历期较为困难。可用于各虫态发生期及年发生代数的观察。“试管法”既能较好的观察卵、幼虫、蛹的发育过程及历期,又能较好的观察各虫态发生期及年发生代数。可用于生活史及卵、幼虫、蛹发育过程的观察。“玻璃夹板法”观察幼虫、蛹发育过程及历期效果较好,可用于幼虫、蛹发育过程及历期的观察,也可用于年发生代数的辅助观察。“培养皿法”在卵期观察中,有一定的使用价值。     

川三蕊柳扦插繁殖试验

以川三蕊柳1年生嫩枝、1年生粗壮枝和2年生粗壮枝为试材,选取水塘、水田和旱地3种不同生境,采用直插法和斜插法进行扦插育苗试验。结果表明:川三蕊柳扦插育苗对生境要求较高,以1年生粗壮枝在水田中用直插法进行扦插育苗,其苗木的成活率最高,生长最好。     

龟石水库降水量特性分析

根据龟石水库水文站1960～2011年降水量资料,利用Spearma检验法、Mann-Kendall法、滑动平均法对年降水量的趋势进行分析,结果表明龟石站1960～2011年年降水量呈现下降趋势。     

基于Landsat影像的土地覆盖变化信息提取方法研究——以贵阳市为例

基于贵阳市中部地区2017年和2019年Landsat8 OIL地表反射率数据,采用图像差值法、归一化植被指数差值法、主成分分析差值法3种方法进行土地覆盖变化信息的提取.精度评价结果表明:主成分分析差值法虽然漏检率高于归一化植被指数差值法,但正检率和错检率均明显优于其他2种方法,是3种方法中更适合该研究区提取土地覆盖变...     

栽培松茯苓期间的白蚁防治技术初报

采用5种白蚁防治方法,从防治效果、成本、操作复杂性上进行分析与比较,其结果差异明显。克百丹防治法在普通防治法上作了改进,防治效果有提高,克百丹防治加诱杀法比克百丹防治法、普通防治法防治效果更好,但成本偏高。克百丹防治加当年诱杀法与克百丹防治加隔年诱杀法2种方法都有特别好的防治效果,但克百丹防治加隔年诱杀法历时2年,较克百丹防治加当年诱杀法工作量大,防治成本偏高。     

青海省互助县北山林区森林生态系统功能经济价值评估

利用2000年天然林保护区森林资源现状调查资料,采用影子工程法、机会成本法和替代花费法对互助北山林区森林生态系统功能的经济价值进行了评估.     

青海省森林火险天气等级预报方法的应用分析

青海省森林火险天气等级预报方法的应用分析王繁强，暴荣英，王恒（青海省气象台）青海省森林火险等级天气预报原设计包括三种预报方法：综合指标法、实效湿度法和８０１法。经１９９０年１０月至１９９１年毛月试用后，通过统计、对比分析，并考虑到业务的实用性，选用了...     

海城林木害虫天敌姬蜂调查初报

2014年至2017年,利用网捕法、灯光诱集法与室内饲养法,对海城市天敌姬蜂进行调查研究。鉴定出海城地区林木害虫天敌姬蜂种类14亚科46属60种,提供了海城市已知种类分布名录,为海城市森林病虫害生物防治奠定了坚实基础。     

提高毛梾产苗量的有效方法——种子沙藏育苗法

毛梾(Cornus walteri Wanger.)又叫车粱木(山东),油树、椋子木(陕西),是一种较好的木本油料树种。但由于种子含油,种皮极其坚硬,不易吸水,播种育苗往往当年产量低,甚至二、三年才能发芽出土。因此,在育苗中加强种子处理和出苗期的圃地管理工作,对提高育苗效果,是一项十分重要的关键措施。自1972年以来,我们曾试验过许多种种子处理方法,如冷冻法、火坑催芽法、硫酸处理法、温水(30—80℃)浸种法、牛粪拌种法以及混沙埋藏法等。据1973—1976年连续试验证明,混沙埋藏法最简便有效。现将毛梾种子混沙埋藏育苗的具体方法和     

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.