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。     

北方树木冻害的防护

一、产生冻害的原因 （一）内因 1.与树种、品种有关：不同的树种或不同的品种,其抗冻性不同。 2.与树龄、生长势有关：幼树贪青徒长,枝条组织不充实,特别是枝条的先端对严寒敏感,易受冻;生长势旺盛的树木抗寒。     

北方园林树木冻害的防护

一、产生冻害的原因(一)内因1.与树种、品种有关:不同的树种或不同的品种,其抗冻性不同。2.与树龄、生长势有关:幼树贪青徒长,枝条组织不充实,特别是枝条的先端对严寒敏感,易受冻;生长势旺盛的树木抗寒。3.与枝条内部的糖类含量有关:枝条内部糖类含量高的,抗冻性强。4.与枝条的     

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。     

南京市区桂花冻害调查与分析

桂花是南京栽培历史比较悠久的常绿阔叶树种。调查了南京市几大公园桂花的冻害情况,结果显示南京市桂花一共有12个品种受冻,冻害等级主要集中在2级,占43%。受冻最多的品种为四季桂,占冻害株数的66%,且大部分为中度受冻以上,嫩叶、上部枝条受害,其他品种冻害株数较少。并讨论了引起桂花冻害的原因及防寒的技术措施,为桂花品种的引种栽培和管理提供了参考资料。     

昆明市2013—2014年冬春季园林植物低温冻害研究

采用实地调查法,对2013—2014年冬春季昆明出现的极端低温和持续低温天气导致的园林植物受冻状况进行调查分析。结果表明,受冻害园林植物总计63科107属133种,划分了受冻害等级,统计了不同受害等级的植物数量,对产生冻害的原因进行分析,提出园林植物防冻害及保护建议。     

广德县古树树势与健康状况评价

在全面普查和专项补充调查的基础上,基于树形与生长方面的9个量化指标对安徽省广德县古树树势与健康状况进行综合评价。结果认为,全县古树总体上树势一般,呈中等健康水平,但不同的树种差别较大,其中生长缓慢的大乔木树种,凡处于中年阶段的古树,大多树势生长旺盛,健康等级高;乡土树种古树适应当地自然条件的能力较强,生长较好,健康等级较高;而速生树种或引入归化树种的古树,在处于生长的末期阶段,一般长势不佳,健康等级较低;具有量多面广的同一古树,树势旺盛,健康等级较高。不同保护级别的古树,树势和健康等级也各有差异,总的趋势是保护级别越高,树势越差,健康等级越低。生理老化、自然灾害、环境恶化、病虫危害、管护不善等则是当前影响古树树势和健康的主要因素。     

永安桉树造林及其冻害情况调查

永安地处福建省西北部,是福建省桉树造林新区,近年桉树造林面积相当于全省桉树造林总面积的五分之一,其年生长量达到或超过福建漳州桉树中心产区;1999年底遇到寒流,受冻严重,但不同桉树树种受冻情况差别极大,为桉树抗寒能力选择提供难得机遇;三年生以上桉树冻后采伐利用扣除造林成本,有丰厚的毛利润,同时树蔸萌芽更新情况良好,当年高生长量达4m以上。     

小兴安岭阔叶红松林粗木质残体基础特征

以小兴安岭典型阔叶红松林大面积固定样地(9hm2)为对象,分析粗木质残体(CWD)的物种组成及数量特征、径级结构、存在形式、腐烂等级,揭示小兴安岭阔叶红松林CWD的基础特征。结果表明:9hm2典型阔叶红松林固定样地内共计有胸径≥2cm的CWD3418株(由于高度腐烂鉴别不出种的CWD有864株,占总个体数的25.3%),CWD的密度、胸高断面积和体积分别为380株.hm-2、15.80m2.hm-2和90.1m3.hm-2;花楷槭和枫桦是阔叶CWD的主要组成树种,红松和冷杉是针叶CWD的主要组成树种;针叶树种的胸高断面积(9.12m2.hm-2)和体积(57.68m3.hm-2)分别达到总体CWD的57.7%和64%;在各存在形式下不同种的CWD数量随着径级的增加而减少,均呈反J型;除未知种以外,其他CWD都主要以枯立木、干基折断和干中折断形式存在;针叶树种根桩形式CWD的数量随着径级的增加而增加,这一规律有别于其他种;样地内各树种CWD腐烂等级都大致呈正态分布,主要集中在Ⅱ和Ⅲ腐烂等级上;除针叶树种的Ⅴ腐烂等级外,各树种不同腐烂等级CWD的数量都随着径级的增加呈减少的趋势。     

三明市冻害桉树更新技术综述

桉树具有生长快、适应性强、用途广、效益好等特点,引种桉树,优化三明市树种结构.截至2000年止,全市共引种桉树树种18种,面积1466.67 hm2.但在1999年,三明市遭到50年一遇的极端低温,大部分桉树冻害严重,冻害程度达Ⅲ-Ⅳ级.为减少损失,采取各种措施,对受冻桉树截杆、"伐桩"、稻草覆盖、病虫害防治、除草培土、施肥、去萌等综合技术,促进受冻桉树萌芽更新,取得明显成效.     

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。     

保山市核桃幼树冻害成因及防治技术措施

在实践和调查研究基础上,论述保山市核桃幼树冻害发生发展规律、冻害症状及危害程度,认为冻害的主要成因是低温或降霜降雪,干旱、栽培管理措施及选择栽培品种不当会加剧冻害发生的程度.藉此提出了预防核桃幼树冻害和处理冻害植株的技术措施.     

Rapid freezing injury in red spruce: seasonal changes in sensitivity and effects of temperature range

On calm, cold days in winter, sun-exposed needles of red spruce (Picea rubens Sarg.) may warm 10 to 20 degrees C above ambient air temperature, and undergo rapid (>/= 1 degrees C min(-1)) fluctuations in temperature as light breezes or passing clouds alter the energy balance of the foliage. It has been proposed that the resulting rapid freeze-thaw cycles (freezing stress) cause a type of winter injury in montane red spruce that is characterized by necrosis of sun-exposed foliage. In autumn and winter, we monitored rapid freezing stress response of needle sections from 10 montane red spruce trees by subjecting needles to rapid freezing over the temperature span typically recorded in the field. In autumn, experimental rapid freezing stress produced severe injury only at temperatures considerably lower than expected for that time of year. In winter, rapid freezing caused occasional, moderate injury in fully hardened foliage of trees susceptible to both slow and rapid freezing. Seasonal changes in sensitivity to rapid and slow freezing were correlated, suggesting that environmental factors that are known to affect sensitivity to slow freezing may also affect sensitivity to rapid freezing. Experimental manipulation of the start and end temperatures of rapid freezing stress events showed that moderate to severe needle injury can occur in susceptible trees at temperature spans slightly more extreme than those typically recorded in the field. The extent of injury was similar at different starting temperatures if rapid freezing occurred over the same temperature span. Year-old foliage was consistently less sensitive to rapid freezing stress than current-year foliage, but some year-old foliage was damaged when the rapid freezing stress regime caused severe injury in current-year foliage. We conclude that rapid freeze-thaw cycles can explain light to moderate injury of current-year foliage, but they do not explain the more severe and widespread pattern of foliar damage that has occurred intermittently over at least the last 18 years.     

Effects of radiational heating at low air temperature on water balance, cold tolerance, and visible injury of red spruce foliage

Recent studies have shown that winter needle mortality in red spruce (Picea rubens Sarg.) is increased by exposure to direct solar radiation, possibly as a result of photo-oxidative damage, accelerated winter desiccation, or reduced cold tolerance due to heating of sun-exposed needles. In an experiment at controlled subfreezing air temperatures of -10 to -20 degrees C, visible radiation was less effective than infrared radiation in producing needle desiccation and visible injury during freeze-thaw cycles. However, visible radiation produced a red-brown color in injured needles, similar to natural winter injury, whereas injured needles exposed to infrared radiation were yellow and injured needles kept in darkness were dark brown. Thus, visible radiation was necessary to produce the red-brown color of damaged needles, but not the injury itself. Needle desiccation was not strongly correlated with visible injury, but the pattern of variation in visible injury among trees and the positive correlation between electrolyte leakage and visible injury suggested that freezing damage following freeze-thaw cycles might cause the visible injury. This was confirmed by a second experiment that showed loss of cold hardiness in needles thawed by radiational heating for six consecutive days. Even with a constant nighttime temperature of -10 degrees C, six days of radiational heating of needles to above freezing caused a small (2.8 degrees C) mean decrease in needle cold tolerance, as measured by electrolyte leakage. Continuous darkness at -10 degrees C for six days resulted in an estimated 5.6 degrees C mean increase in needle cold tolerance. Freezing injury stimulated desiccation: cooling at 4 degrees C h(-1) to -43 or -48 degrees C increased the dehydration rate of isolated shoots by a factor of two to three during the first day after thawing. Within three days at 15 to 22 degrees C and 50% relative humidity, the mean water content of these shoots fell to 60% or lower, compared to 90% or greater for unfrozen controls or shoots subject to less severe freezing stress. In some but not all severely freeze-stressed shoots, accelerated needle desiccation and abscission were accompanied by a red-brown color typical of red spruce winter needle injury. We conclude that severe winter desiccation in red spruce may often be due to prior freezing injury, increased as a result of exposure to direct solar radiation. Furthermore, freezing injury in red spruce may sometimes cause desiccation and abscission of green needles.     

南平市区引种树种1999年冬季冻害调查

低温冻害是树木引种的大敌。南平城区及近郊主要街道和单位引种树种在 1 999年 1 2月 2 1～ 2 3日的低温冻害天气中 ,有 5 3种树种遭受各种程度冻害 ,其中严重冻害 4级以上有 40种 ,地面部分全部冻死的有 2 4种。在今后引种工作中 ,应引起足够重视 ,以减少损失     

Effects of simulated thaw on xylem cavitation,residual embolism,spring dieback and shoot growth in yellow birch

Yellow birch seedlings (Betula alleghaniensis Britt.) that had lost more than 90% of their stem hydraulic conductivity during ambient winter temperatures were exposed to 0 and 20 days of a simulated winter thaw followed by a 48-h freezing treatment at 0, -5, -10, -20 and -30 degrees C. After measuring freezing injury to shoots and roots, the seedlings were placed in a greenhouse where recovery of xylem conductivity and new growth were measured. Shoot xylem cavitation was measured as percent loss of hydraulic conductivity. Shoot freezing injury was assessed by electrolyte leakage (EL) and root freezing injury was assessed by EL and triphenyl tetrazolium chloride reduction. Seedlings pretreated with thaw had higher stem water contents and suffered more freezing damage to roots and shoots (at -20 and -30 degrees C, respectively) than unthawed seedlings. After 3 weeks in a greenhouse, seedlings from the 0, -5 and -10 degrees C freezing treatments showed complete recovery of xylem conductivity, with substantially increased stem water contents. Poor recovery of hydraulic conductivity was observed only in seedlings that were subjected to freezing treatments at -20 and -30 degrees C, regardless of thaw treatment. Of these embolized seedlings, however, only those not previously thawed showed recovery of hydraulic conductivity or regained stem water content after 9 weeks in the greenhouse. Shoot dieback, bud burst and length of new shoots were significantly related to the extent of stem xylem cavitation and freezing injury. We conclude that (1) the simulated winter thaw predisposed yellow birch seedlings to freezing damage in shoots and roots by dehardening tissues and increasing their water content; (2) root freezing damage in turn affected the seedlings' ability to refill embolized stem xylem, resulting in considerable residual xylem embolism after spring refilling; (3) further recovery of stem xylem conductivity was attributable to growth of new vessels; (4) and the permanent residual embolism, together with root and shoot freezing injury, caused increased dieback, bud mortality and reduced growth of new shoots.     

Effects of xylem cavitation and freezing injury on dieback of yellow birch (Betula alleghaniensis) in relation to a simulated winter thaw

Shoot dieback, shoot growth, stem xylem cavitation, stem and root freezing injury, and root pressure were measured in 2-year-old, cold-hardened, potted yellow birch (Betula alleghaniensis Britt.) seedlings that had been subjected to a simulated winter thaw for 0, 5, 10, 19 or 27 days followed by 10 weeks at -10 degrees C. Stem xylem cavitation was determined as percent loss of hydraulic conductivity. Stem freezing injury was measured as electrolyte leakage (EL). Root freezing injury was determined by EL and by triphenyl tetrazolium chloride (TTC) reduction. Thaw duration was significantly correlated with dieback, new shoot growth, stem xylem cavitation, stem and root freezing damage, and root pressure (P < 0.05). In particular, shoot dieback was positively correlated with stem xylem cavitation (P < 0.001), residual stem xylem cavitation (P < 0.01) and root freezing injury (P < 0.010), but only weakly correlated with stem freezing damage (P < 0.05). In roots, freezing damage was negatively correlated with root pressure (P < 0.05), which, in turn, was negatively correlated with residual stem xylem cavitation after root pressure development. In stems, there was no correlation between freezing damage and xylem cavitation. We conclude that long periods of winter thaw followed by freezing resulted in freezing injury to roots concomitant with a reduction in root pressures, leading to poor recovery from freezing-induced xylem embolism.     

Cold acclimation of Pinus contorta and Pinus sylvestris assessed by chlorophyll fluorescence

Needle samples of six provenances each of lodgepole pine (Pinus contorta Dougl. var. latifolia) and Scots pine (Pinus sylvestris L.), originating from latitudes 55 to 68 degrees N in western Canada and northern Sweden, were collected during the autumn and subjected to freezing temperatures in the range of -8 to -29 degrees C on three occasions in September and October. Needle injury was assessed by two different methods: visual assessment and chlorophyll a fluorescence. Chlorophyll a fluorescence data showed a highly significant correlation with the visual assessments of injury, indicating that the technique can be used as a simple, non-destructive and objective measure for rapid detection of freezing injury and for ranking of needle materials with respect to development of cold acclimation. The analyses showed that, during the autumn, lodgepole pine needles were more hardy and acclimated to low temperatures earlier than Scots pine needles.     

Frost hardiness of Picea rubens growing in spruce decline regions of the Appalachians

It has been proposed that pollutants predispose Picea rubens Sarg. growing in the high Appalachians to frost damage. The pattern of autumn hardening of P. rubens growing at Whiteface Mountain, NY, and Newfound Gap, NC, was monitored by detaching shoots at 1-3 weekly intervals, air freighting them to Scotland, and freeze-testing them. The temperatures that produced freezing injury from August 1986 to January 1987 were compared with minimum air temperatures recorded in those months at nearby meteorological stations over 22 previous years. There was only weak evidence that the onset or degree of frost hardening was inadequate to protect the trees from direct freezing injury (as opposed to winter desiccation). Historically, minimum air temperatures occasionally fell below the lethal temperature for a 10% kill (LT(10)), but they rarely fell below the LT(50). The trees hardened rapidly in the autumn (max. 2.2 degrees C day(-1)) to between -30 degrees C and -40 degrees C by January (LT(50)), including trees showing visible decline on Clingman's Dome, TN. Individual trees differed in hardiness by up to 10 degrees C. It is concluded that any pollutant-induced susceptibility to freezing injury is insufficient, on its own, to account for forest decline in the Appalachians.     

2013年冬季海口林场常绿植物冻害调查分析

针对2013年冬季昆明遭遇了低温雨雪天气的影响,对昆明市海口林场露天苗圃地栽培的常绿植物冻害进行了调查。结果显示：所调查的43种植物中,16种植物有不同程度的受冻,占37．2％;冻害级别3级以上有8种,分别是缅桂、清香木、小叶女贞、尖叶木樨榄、小叶榕、马蹄荷、三角梅、鹅掌柴,占18．6％;部分树种幼树和成年大树冻害程度一样,部分树种随着年龄增加,冻害程度降低。根据这次冻害的发生情况,提出了在今后苗木生产过程中,要针对性地对易受冻害的苗木进行保护管理,推广应用抗冻能力强的植物,改良抗冻能力,加大应用乡土绿化植物的力度。