八棱海棠一年生播种苗苗高年生长规律研究

以八棱海棠1 a生播种苗为研究时象,对其苗高生长规律和苗高与地径、生态因子的关系等进行研究.试验结果证明:Logistic方程可较好地反映苗高生长规律,苗高生长呈现"慢-快-慢-快-慢"的节律,并以此将苗高年生长过程划分为6个生长期.通过苗高生长规律与气象因子的相关分析,证明日平均气温是影响苗高生长的主要气象因子.     

欧洲鹅耳枥2年生播种苗年生长动态

以欧洲鹅耳枥2年生播种苗为研究对象,对其苗高、地径、生物量的年动态变化和苗高与地径、生态因子的关系等进行研究。结果表明:苗高、地径两者生长基本符合"慢—快—慢"的生长规律,可用Logistic方程来拟合,同时把苗高和地径的生长可分为生长初期、生长盛期和生长末期;苗高在生长盛期有一连续生长高峰期,而地径在生长盛期有2次高峰期,且后期比前期更明显;苗高与地径变化之间呈线性相关,播种苗各部分生长具密切相关性,呈负相关性;通过苗高、地径生长规律与气象因子的相关性分析,表明旬平均气温是影响苗高的主导因子,其他气象因子对地径生长无显著影响。     

琼岛杨一年生播种苗生长节律研究

于2019年5月6日到12月25日对海南省琼岛杨Populus qiongdaoensis一年生播种苗的苗高、地径生长量进行定期观测,采用Logistic方程进行生长进程拟合,研究琼岛杨的苗期生长节律。结果表明,琼岛杨苗高和地径生长都呈现"慢—快—慢"的"S"形生长规律,且苗高、地径生长量与Logistic方程的回归相关性达到极显著水平,其相关系数分别达0.994和0.996。苗高生长速生期约119 d,占生长期的39.67%,占苗高年总生长量的63.77%;地径生长速生期约125 d,占生长期的45.42%,占地径年总生长量的66.15%。     

千年桐苗木生长规律研究

以千年桐1年生播种苗为研究对象,对其苗高、地径的生长规律和苗高、地径与气象因子的关系等进行研究。试验结果表明：Logistic方程可较好地反映1年生千年桐的苗高、地径生长规律;日平均气温是影响苗高生长的主要气象因子,气象因子与地径生长关系不大。     

凹叶厚朴种子保存方法及幼苗生长规律

对凹叶厚朴的种子保存方式及相应的播种苗的发芽情况、幼苗生长规律进行统计分析。结果表明:冷藏处理的凹叶厚朴种子发芽慢、发芽持续时间长;播种苗株高生长呈"S"型的慢—快—慢的规律,地径与叶幅生长表现出快—慢—快—慢的规律;株高、地径、叶幅三者之间的生长呈极显著正相关;种子经沙藏的凹叶厚朴发芽时间、出苗速度及发芽率均优于冷藏处理,而且,沙藏处理的苗高、地径、叶幅的累积生长量相应地大于冷藏处理。     

10个美国紫薇家系苗期生长规律分析

以美国紫薇10个家系1 a生实生苗为研究对象,探讨其高生长节律,旨在为紫薇的选择育种研究提供参考。对各家系苗高生长进程分析表明,紫薇不同家系苗高年生长规律基本一致,呈现"慢-快-慢-快-慢"的生长节律,2个生长高峰期为7月中下旬至8月初、8月下旬至9月初,其苗高生长量约占全年生长量的40%~50%;对10个家系的苗高、地径生长性状分析结果表明,家系间苗高、地径生长差异极显著,苗高、地径生长最大的2号、6号家系分别高出生长量最小的4号、7号家系150%和49%。各家系内单株之间也存在丰富的变异,苗高平均变异系数为30.9%,地径平均变异系数为22.35%。家系间、家系内存在较为丰富的变异,预示着具有较大的选择潜力。     

红桤木引种栽培试验

2005-2007年,从美国引进红桤木在江苏六合和安徽南陵进行引种造林试验,结果表明红桤木具有较好的生长适应性,是一个优良的速生树种。造林3 a时,平均树高生长量分别达到3.98 m和5.01 m,地径生长量达到5.9cm和7.14 cm。实生红桤木个体间早期生长差异较大,地径与苗高生长显著相关。引种红桤木4年生时已大量开花结实,进入性成熟期。     

伞花木1年生播种苗生长节律研究

为掌握伞花木1年生播种苗的年生长规律,为伞花木苗木的高效培育提供科学依据,本文采用Logistic生长曲线方程对伞花木1年生播种苗的苗高与地径生长进行拟合,相关系数分别为0.995和0.997,均达极显著水平.根据伞花木1年生播种苗的实际观测值建立动态生长模型,并将其播种苗1年生长过程划分为出苗期、生长初期、生长盛期、生长后期.苗高的速生期为6月中旬-8月下旬,地径速生期为6月上旬-9月上旬,地径速生期比苗高速生期提早20 d结束,地径用46.67％的生长时间完成了65.43％的生长量.1年生苗木地上部分粗壮、地下部分具深根性,其根可深达土层32.92 cm处,且侧根数量较多,分布广.     

昆明地区美洲黑杨N895当年生扦插苗及移栽苗的年生长特点

以黑杨N895当年生健壮苗木截成的插穗条、苗木为材料,采用Logstic拟合美洲黑杨N895当年生扦插苗、移栽苗苗高、地径的生长模型,分析在昆明地区美洲黑杨N895当年生扦插苗、移栽苗年生长节律。结果表明,在昆明地区种植美洲黑杨N895当年生扦插苗、移栽苗地径、苗高生长量分别在10月、11月以后停止生长,苗高、地径年生长均呈现"慢-快-慢"的生长节律,表现为"S"型生长曲线,利用Logstic模型拟合效果显著,相关系数均达0.99以上,生长模型分析可行。根据Logstic模型将其生长过程分为成活期、生长前期、速生期、生长后期4个时期。不同阶段其苗高、地径生长起止时间存在差异。     

不同种源北非雪松1年生播种苗的年生长规律

对北非雪松5个种源1年生播种苗的苗高和地径生长进行研究,5个种源的苗高都符合"S"型生长曲线,苗高生长可采用Logistic生长曲线拟合,同时可把生长期划分为4个阶段;地径生长规律与苗高生长不同,Logistic生长曲线拟合程度不高,不能作为生长期划分的依据。5个种源的苗高和地径生长规律相似,但苗高和地径生长量存在显著差异,美国加利福尼亚种源和亚利桑那种源苗高、地径生长量均高于突尼斯、阿尔及利亚和摩洛哥种源。     

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.