南宁苗圃园林植物寒冻害调查分析及预防对策

本文以南宁市嘉和城苗圃为对象,通过对植物外部形态进行感观鉴定,对植物的叶、芽、枝、整株等的生长指标、组织褐变等进行观察,把园林植物受寒冻害程度划分为五个等级,然后根据等级评价标准,对2011年苗圃园林植物受寒冻害情况进行调查与数据收集分析。结果表明,持续低温给苗圃园林植物造成明显寒冻害,热带植物种类抗寒性差,受寒冻害严重,甚至整株死亡,多为IV-V级。合理选择植物品种、做好寒冻害来之前的防寒措施和植物受冻后的及时补救措施是避免园林植物大面积受寒冻害的关键措施。     

宝鸡市区2008年早春园林植物冻害调查

通过对宝鸡市区园林植物冻害调查发现,不同树种受害等级不同;同一树种在不同的栽培环境,不同生长状况;不同部位以及不同的管理措施条件下,受冻等级不同.对受冻等级不同的植物,采取不同的补救措施.     

杭州园林植物冻害调查与分析

2016年1月23-25日,浙江省杭州市连续3 d最低温-8~-9℃,许多园林植物遭受不同程度冻害。于2016年2月上中旬、2016年4月下旬至5月下旬对杭州植物园、西湖景区公园、部分街道绿化及住宅小区园林植物进行调查,并对其受冻害情况及其冻后养护恢复情况进行调查分析。结果表明,共有19科34属41种园林植物遭受不同程度的冻害,其中约83%为引种植物;66%的植物冻害等级为轻度或中度,不需人为干预或适度修剪就能恢复正常生长;27%的植物冻害等级为重度,长势明显趋弱;7%的植物出现受冻死亡的现象。建议在森林城市建设中,植物的引种遵循科学规律,重视驯化,尽量选用乡土植物与外来植物相搭配的配置方式,加强日常管护,降低低温逆境胁迫对园林植物的影响。     

乐昌市园林植物冻害调查与分析

调查了经历乐昌市2020年12月—2021年1月低温天气的园林植物的受冻害、需处理和恢复的情况,记录到受冻害的园林植物有124种（含杂交种、变型和园艺品种）,具有受冻害种类较多、外来植物受冻害比例高和同种植物受冻害程度因地或苗而异的特点。受冻害的主要原因除了长时间的低温天气外,还有苗木栽培时间短、引种不科学、管理粗放等。建议遵循适地适树原则,科学选择植物种类,区别选择南北两地种类;尽量使用本地苗圃培育的苗木,少用外来苗木;加强人工管护和灾后处理;提前炼苗。     

天津滨海新区园林植物冻害的防护对策

冻害是指气温过低,树木因无法适应这种低温而出现的冻伤甚至死亡的现象.由于北方地区的冬季气温普遍偏低,且持续时间长,树木受冻害的情况严重,已经威胁到了园林植物的生存问题,因此做好防冻害工作是现代园林工作人员的重点工作,针对产生冻害的原因提出相应的防护对策.     

北京城郊雪松冻害调查及分析研究

2010年3～4月,对北京城郊雪松冻害情况进行调查分析,6月份对其恢复情况进行了跟踪观测。结果表明,骤然降温和极端低温是雪松受冻害的主要原因;大多数雪松均有不同程度的冻害发生,城八区和郊区县冻害稍轻,五环外苗圃受冻害较严重;叶片受冻Ⅰ~Ⅲ级,枝条受冻Ⅰ~Ⅱ级雪松开春后基本能恢复树势,景观效果不受影响;今后应做好边缘树种冬季防寒工作,减少冻害发生。     

昆明园林绿化植物冻害成因分析和种类选择探讨

指出了昆明近几年城市园林植物低温冻害严重,尤其是2016年的低温冻害更加严重,导致昆明城区园林植物大量冻坏冻死和造成较大的生态和经济损失。分析了昆明园林植物冻害的主要成因,探讨了其种类的选择,以期提供参考。     

江西桉树冻害的调查研究

1991年底的寒冷低温降雪天气,使江西大部分地区的桉树受到不同程度的冻害,为及时了解冻害的情况和原因,我们两次选点调查,为便于比较分析,书桉树的冻害程度分为5个冻害级。调查结果表明,全省桉树冻害规律是以北纬27°为界,呈“∩”形,将江西栽培的桉树分成两部分,北部受冻较重,南部受冻较轻,尤以赣南的南康、大余两县和信丰县的部分受冻最轻。根据桉树冻害情况归并为4种冻害类型,即较重冻害、中等冻害、较轻度冻害和轻度冻害。冻害的主要原因是低温中极值低温的出现和降(回)温速度太快。内外因素(如品种、种源、地形等)造成的冻害差别要在一定的极值低温条件下才表现出来。受冻后的桉树通过恢复生长完全可以成林。最后提出对今后江西发展桉树的看法和建议。     

树木冻害调查研究

1991年12月29日的低温使福州树木园300多种树木受冻害,根据树木叶片及枝条受冻害的不同程度,将树木冻害划分为5个等级;树木受冻害的主要原因有3点,一是树种本身特有的生物学特性,二是降温过程及降温前的气温条件,三是树木生长的小气候环境。     

江西桉树冻害的调查研究

1991年底的罕见低温,使江西大部分地区的桉树受到严重的冻害。调查结果表明:全省桉树冻害规律是以北纬27°为界,呈反“U”字形,将江西栽培的桉树分成两部分。北部受冻较重,南部受冻较轻,南康、大余两县和信丰县的部分地区受冻最轻。冻害的主要原因是低温中极值低温的出现和降(回)温速度太快。内外因素(如品种、种源、地形等)造成的冻害差别要在一定的极值低温条件下才表现出来。受冻后的桉树通过恢复生长完全可以成林。     

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.