茶梢蛾幼虫空间分布及其抽样技术

对茶梢蛾幼虫的空间分布型及抽样技术的研究结果表明,幼虫为普通聚集分布,其基本成分是面积为一株油茶大小的个体群,个体间相互吸引。调查时以棋盘式取样为佳。根据空间分布型分析,计算出序贯抽样模型为:最适理论抽样数模型为:     

云杉顶芽瘿蚊空间分布型及抽样技术研究

通过调查和计算,明确了云杉顶芽瘿蚊的空间分布型呈聚集型的一般负二项分布。用Ｉｗａｏ方法给出了抽样技术,理论抽样数当ｔ＝１０,Ｄ＝０３时,ｎ＝６３５９／ｘ＋４４４,如果防治指标定为每株２２个虫瘿时,序贯抽样的累积虫瘿数量界限为：Ｔ０（Ｎ）＝２２Ｎ±１７８７３２Ｎ。林间随机取样以平行线和“Ｚ”字形为最佳     

红缘天牛幼虫空间分布型及抽样技术的研究

红缘天牛幼虫在沙棘林间的间分布型属聚集分布，聚集强度随种群密虎增大而增加。用折线，平行线，分行，随机式进行取样，以折线取样法代表性误差最小。采用Ｉｗａｏ提出了理论抽样公式，确定了不同虫口密度（Ｘ）在ｔ＝０．９，ｄ＝０．３时需理论抽样数为：ｎ＝８．４２６７／ｘ＋７．１４６。     

木兰突细蛾空间分布型及其应用的研究

采用７种聚集度指标法测定了木兰突细蛾卵和幼虫的空间分布型。结果表明：卵和幼虫在木兰科植物人工林内部呈聚集分布，幼虫分布的基本成份是个体群，个体间相互排斥。卵分布基本成份是疏松的个体群。应用Ｉｗａｏ＇ｓ方法，分析并计算林间调查的最适抽样数，进行了幼虫序贯抽样的计算。     

松埃尺蛾空间分布型及其在实践中的应用

本文采用比较频次法、聚集度指标法研究了松埃尺蛾越冬代蛹和第一代幼虫的空间分布型。结果表明：越冬代蛹、第一代幼虫的空间分布型呈负二项分布，其分布的基本成分为个体群，个体间相互排斥。并应用Ｉｗａｏ方法分析、检验了不同虫口密度下林间调查的最适抽样数，列出序贯抽样分析表。     

毛白杨透翅蛾幼虫空间分布型及其应用的研究

毛白杨透翅蛾幼虫主要危害毛白杨苗干部。设１０块标准地,经多次适合性检查,其结果表明,毛白杨透翅蛾幼虫的空间分布状态全部呈现负二项分布,用多种聚集度指标测定,则均属聚集分布。由此建立了不同密度下的理论抽样曲线图和序贯抽样检索表,确定了序贯抽样公式：Ｔｏ（ｎ）＝０．３ｎ±１．２ｎ。     

竹小蜂幼虫空间分布型及其抽样技术研究

对竹小蜂幼虫空间分布型及抽样技术进行研究,结果表明,幼虫种群呈普通聚集分布。在较低密度下,其基本成分是面积为4株楠竹大小的个体群。个体间相互吸引。进行化学防治以后,对种群的空间分布型无影响。但因种群密度降低而使种群聚集程度提高。幼虫在竹梢中部的分布显著不同于上部,而与下部无显著差异。在株内取样调查时,以竹梢中部为最佳:进行样地调查时,以双对角线法取样为最佳。     

鞭角华扁时蜂滞育幼虫空间型测报抽样技术研究

鞭角华扁叶蜂滞育期幼虫通过空间分布型参数Ｋｕｎｏ指数、聚集指标Ｉ、ｍ／指数、扩散型指标Ｉσ及α、β值分析结果，滞育期幼虫呈聚集分布、个体群。应用空间分布型参数得抽样公式；序贯抽样累积虫量界限林间９０％抽样可靠性指标；５０条／ｍ２需样地４２块，２００条／ｍ２需样地２２块，３５０条／ｍ２需样地１９块。     

灰拟花尺蛾幼虫空间分布的研究

通过对桦树林抽样调查与几种聚集度指标检验法相结合，说明花尺蛾幼虫空间分布型为聚集分布，分布的基本成分是个体群。聚集强度随种群密度的升高而增加，用1wa 0的方法，确定了不同虫口密度下的理论抽样数及序贯抽样检索表．为防治提供了理论依据。     

粗鞘双条杉天牛的危害分布和抽样方法研究

本文采用聚集度指标，频次比较及回归分析方法对粗鞘双条杉天牛在杉木人工要的为害分布进行了研究。结果表明，粗鞘双条杉天牛在人工杉木林中为害分布属受密度制的聚集型分布， 临界密度为ｍｏ＝２．５９６１株样方；受害株的分布以植株群为基本单元，其形成是由于该天放散活动能力弱，产卵范围比较集中所致。根据回归式ｍ＝０．６２８０＋０．７９０５ｍ，可确定随机抽样的理论抽样数θ，θ＝ｔ＾２／Ｄ＾２（ａ＋１／Ｘ＋β＋２１     

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.