云南林业气象灾害及气象服务需求研究

通过对32名云南省林业专家及17个典型林业灾害隐患点进行调查,对云南省林业气象灾害隐患点、林业气象服务需求进行分析。结果表明,云南省林业气象灾害类型主要为火灾,其次为病虫害、雪害、干旱、风灾、雹害和雨凇;隐患点主要分布在昆明、楚雄、昭通、文山、迪庆、丽江、怒江和普洱等地区,隐患点海拔差别较大;对云南林业生产影响最大的气象灾害主要为干旱和低温(雨雪)冰冻,其次是大风和冰雹。林业部门对气象服务的需求依次为森林火险气象条件预警预报、森林干旱监测预报、林业病虫害顸报和森林火点监测等,调查对象认为获取林业气象信息最为有效的途径是预警系统,其次是手机短信和电子邮件,最少的是电话和传真;不同的林地抗灾能力也不同,天然林的抗灾能力要高于人工纯林及树种单一或相对集中的林地。     

天水市不同绿地生态效应研究

本试验对天水市主干道及甘肃林业职业技术学院校园内主要绿化树种进行了降温增湿效应观测,并对不同树种滞尘能力进行了研究,表明在高温季节林地和草坪都有降低地面温度,增加空气湿度的作用,尤其是林地效果更为明显。同一尘源条件下,不同树种的滞尘能力与叶片表面粗糙度差异显著;不同尘源备件下,同一树种滞尘量差异显著;与阔叶树种相比,针叶树种滞尘能力较高,尤其是雪松和云杉。     

贵州省2013年人工造林未成林地干旱灾害受损核查及分析

采用未成林地自然灾害受损核查办法,对贵州省2013年人工造林未成林地干旱灾害受损情况进行省级核查。分别针对不同受灾地域、工程项目、造林年度、混交方式、树种组5个承灾体,分析受损程度等级、株数保留率情况。为积极有效应对干旱灾害,在科学造林、加大抗旱实用技术的推广和完善灾后恢复重建相关政策等方面提出对策和建议。     

辽西朝阳地区三种树种耐旱性比较研究

为筛选朝阳地区造林耐旱树种,以油松、荆条和刺槐3个树种的1年树苗为试验研究对象,从丙二醛和相对电导率两方面变化对持续干旱条件下油松、荆条和刺槐3种树种的抗旱性进行了测定,并综合比较了3个树种对干旱胁迫的响应能力。结果表明:3种树种在丙二醛含量和相对电导率变化上各不相同,抗旱能力强弱顺序为油松最高,刺槐最低。     

岷江上游干旱河谷4个乡土树种的抗旱生理指标主成分分析

在自然干旱胁迫条件下,对5年生油松、岷江柏、刺槐、榆树4个树种的生理生化指标分别在旱季和雨季进行测定,分析讨论了干旱胁迫下,各树种生理生化指标的变化规律及其相关关系。根据4个树种在干旱胁迫条件下各指标的表现,利用主成分分析法对4个树种的抗旱性进行综合评价。抗旱性综合评价结果表明:4个树种的抗旱能力以刺槐的抗旱性最强,油松的抗旱性最差。其排名顺序为:榆树>刺槐>油松>岷江柏。     

高温干旱胁迫对10种常绿阔叶树种叶片生理特性的影响

利用人工气候箱模拟高温干旱环境,研究了高温干旱处理对10个常绿阔叶树种叶片细胞膜透性和游离脯氨酸含量的影响。结果表明,随高温干旱胁迫强度的加剧,各树种叶片的细胞膜伤害率(MIP)和游离脯氨酸含量(FPro)均呈快速上升趋势;供试树种的抗高温干旱能力不同,半致死温度在38⁴6℃之间;以隶属函数法综合分析各树种的抗高温干旱能力,结果表明10个树种的抗高温干旱能力由强到弱依次为:枇杷、广玉兰、女贞、石楠、香叶树、桂花、黑壳楠、深山含笑、香樟和云南樟。试验结果与引种地实地观察结果具有良好的对应性。     

3个优良树种抗旱能力初步研究

樟子松、山杏和油松等3个树种均有较强耐干旱、瘠薄的能力,但三者在不同地块造林成活率差异较大。为比较它们的抗旱能力,对这3个树种的光合生理及水分生理等指标进行了测试,结果表明:在相同的条件下,油松的蒸腾速率和气孔导度更小,这导致其叶片失水速度较慢,这对其储备光合产物、维持体内水分平衡更为有利;油松5月的含水量、束缚水/自由水比值均高于其余二者,并且临界饱和亏数值最大,相同的时间点中根、茎、叶三者水势均低于山杏和樟子松。油松具备更好的抵抗干旱瘠薄能力,上述3个树种中应优先选择油松进行造林。     

重庆市主要外来树种干旱受灾及抗旱能力调查

通过实地调查綦江、涪陵、丰都、彭水等13个区县的30个主要外来树种，统计分析得出2006年我市主要外来树种因高温干旱受灾的情况，即主城及渝西地区的受灾最重、海拔300米以内的受灾最重、浅根性树种较深根性树种受灾严重、自然分布偏南的较偏北的树种耐高温但不耐干旱、阅叶树种比针叶树种受灾严重、栽植土层薄的比土层厚的受灾程度重。并初步确定了抗旱能力最强、最弱和恢复能力最强的树种。     

漫话云南松古树

漫话云南松古树云南松又称飞松、青松。它耐干旱、瘠薄，天然更新良好，是云南首屈一指的用材树种。云南松林地面积占全省林地面积的５２％，活立木蓄积量占全省森林蓄积量总和的３２％，是分布区内荒山绿化和迹地更新的主要树种，是全省飞播造林面积最大的树种。松为“百...     

马褂木等在三峡库区水土保持中的应用效果分析

马褂木等各5个优良地理种源在三峡库区水土保持建设中推广应用造林.通过对造林地土壤监测表明:采用桤木、马褂木等阔叶树种造林后,林地的土壤改良效果明显,水土流失情况得到有效治理和控制.     

Pine mistletoe (Viscum album ssp. austriacum) contributes to Scots pine (Pinus sylvestris) mortality in the Rhone valley of Switzerland

In recent years unusual high mortality of Scots pine (Pinus sylvestris) has been observed in the Swiss Rhone Valley. The exact causes, however, are not known. At a 2‐ha monitoring plot, tree mortality and crown condition have been monitored since 1996. Between 1996 and 2004, 59% of the Scots pines died, most of them following the drought periods 1996–1998 and 2003–2004, while only 15% of the deciduous trees died. Crown transparency, needle discolouration, dead branch percentage, mistletoe (Viscum album ssp. austriacum) rating, Tomicus sp. shoot feeding, male flowering effect, tree stem diameter, crown shading and social tree class assessed in 1998 were used in a logistic regression model to predict tree mortality. Crown transparency, mistletoe rating and percentage of dead branches were found significant in the model and the probability of tree mortality increased with increasing rankings of these parameters. Needle discolouration could be used to substitute ‘dead branch percentage’ as predictor. While crown transparency increased with mistletoe rating, for trees in the same transparency class, trees with medium and heavy mistletoe infection were two to four times more likely to die than trees with no or only low mistletoe infection. For the surviving trees we found that trees with mistletoes showed a significantly higher increase in transparency in the year following a drought than trees without, while in a drought year the opposite was true. At the beginning of the observations no significant differences in transparency had been found between the trees with and without mistletoe. However, by the end of the observation period trees with mistletoe had significantly higher crown transparency. We conclude that mistletoe infection can be considered as both a predisposing factor for tree death, by increasing needle loss following drought and a contributing factor by increasing water stress during drought.     

干旱地区树木耐旱性研究现状评述

本文详细评述了植物耐旱性及其机理，并对耐旱性鉴定方法、耐旱性评价指标以及国内外树木耐旱性研究现状进行了综述，在此基础上，提出了四川西部干旱河谷树木耐旱性研究的重点。     

Tree mortality and biomass loss in drought-affected forests of East Texas,USA

Changes in tree mortality due to severe drought can alter forest structure,composition,dynamics,ecosystem services,carbon fluxes,and energy interactions between the atmosphere and land surfaces.We utilized long-term(2000-2017,3 full inventory cycles) Forest Inventory and Analysis(FIA) data to examine tree mortality and biomass loss in drought-affected forests for East Texas,USA.Plots that experienced six or more years of droughts during those censuses were selected based on 12-month moderate drought severity [Standardized Precipitation Evaporation Index(SPEI)-1.0].Plots that experienced other disturbances and inconsistent records were excluded from the analysis.In total,222 plots were retained from nearly 4000 plots.Generalized nonlinear mixed models(GNMMs) were used to examine the changes in tree mortality and recruitment rates for selected plots.The results showed that tree mortality rates and biomass loss to mortality increased overall,and across tree sizes,dominant genera,height classes,and ecoregions.An average mortality rate of 5.89% year~(-1) during the study period could be incited by water stress created by the regional prolonged and episodic drought events.The overall plot and species-group level recruitment rates decreased during the study period.Forest mortality showed mixed results regarding basal area and forest density using all plots together and when analyzed the plots by stand origin and ecoregion.Higher mortality rates of smaller trees were detected and were likely compounded by densitydependent factors.Comparative analysis of drought-induced tree mortality using hydro-meteorological data along with drought severity and length gradient is suggested to better understand the effects of drought on tree mortality and biomass loss around and beyond East Texas in the southeastern United States.     

Tree vigour and the susceptibility of Douglas fir to Armillaria root disease

In this study the effects of thinning, fertilization and pruning on the vigour of Douglas fir (Pseudotsuga menziesii) and its susceptibility to Armillaria root disease were explored. Tree vigour was defined as the relative capacity for tree growth, expressed as the above-ground biomass increment per unit of photosynthetic tissue, or growth efficiency (GE). It has been hypothesized that trees with higher GE can better resist pathogen attack, and that GE can be used as a predictor of tree susceptibility to disease. In a previous study, four Douglas fir plantations were thinned, fertilized and pruned in all combinations, and the effects of these treatments on tree vigour were measured after 10 years. Root disease was not a factor in the initial study design, and mortality was ignored until 8 years after the treatments were applied. The results of an earlier study were utilized and the correlation between Armillaria root disease incidence and the effects of earlier stand treatments on tree growth was tested. Armillaria ostoyae was the primary mortality agent in the study area. Disease incidence on infested subplots ranged from 2 to 20%. Armillaria ostoyae incidence was the highest at medium tree density (6.1%), slightly lower on the low density (5.6%), and lowest on the unthinned plots (3.8%). There were no significant correlations between disease incidence and previous tree growth. The vigour of trees that became symptomatic or died by 1993 was not significantly different in 1983–85 from the vigour of trees that remained asymptomatic. On these sites, in areas of infestation, A. ostoyae is killing the largest, fastest growing trees, as well as less vigorous trees. Armillaria continues to cause mortality, regardless of the growth efficiency or growth rate of the host.     

Mechanisms of drought response in Thuja occidentalis L. II. Post-conditioning water stress and stress relief

We examined the extent of osmotic adjustment and the changes in relative water content (RWC) and transpiration rate (i.e., relative stomatal function) that occur in water-deficit-conditioned 6-year-old Thuja occidentalis L. (eastern white cedar) trees in response to a severe drought. Trees conditioned by successive cycles of mild or moderate nonlethal water stress (conditioning) and nonconditioned trees were exposed to drought (i.e., -2.0 MPa predawn water potential) to determine if water deficit conditioning enhanced tolerance to further drought stress. Following drought, all trees were well watered for 11 days to evaluate how quickly osmotic potential, RWC and transpiration rate returned to preconditioning values. Both nonconditioned trees and mildly conditioned trees exhibited similar responses to drought, whereas moderately conditioned trees maintained higher water potentials and transpiration rates were 38% lower. Both conditioned and nonconditioned trees exhibited a similar degree of osmotic adjustment (-0.39 MPa) in response to drought relative to the well-watered control trees. The well-watered control trees, nonconditioned trees and mildly conditioned trees had similar leaf RWCs that were about 3% lower than those of the moderately conditioned trees. Following the 11-day stress relief, there were no significant differences in osmotic potential between the well-watered control trees and any of the drought-treated trees. Daily transpiration rates and water potential integrals (WPI) of all drought-treated trees approached those of the well-watered control trees during the stress relief period. However, the relationship between cumulative transpiration and WPI showed that previous exposure to drought stress reduced transpiration rates. Leaf RWC of the moderately conditioned trees remained slightly higher than that of the nonconditioned and mildly conditioned trees.     

白梭梭同化枝对干旱胁迫的生理生态响应

对白梭梭同化枝自然水分胁迫下的季节抗旱特征进行研究。结果表明:自然干旱胁迫条件下,不同生长发育时期同化枝的主导抗旱生理因子不同。5月31日至6月29日盛花期间,同化枝内源ABA含量甚微,气孔导度值与光合强度处于生长发育过程的最高水平,可溶性糖含量呈现下降趋势,而脯氨酸含量略有增加,植物通过渗透调节作用适应此阶段轻度干旱胁迫;6月29日至7月26日盛夏期间,ABA迅速积累,气孔导度值降为生长发育过程的最低值,叶绿素分解,可溶性糖与脯氨酸均呈现快速积累趋势,且可溶性糖积累强度大于脯氨酸;8月9日至8月22日同化枝生长发育后期,ABA急剧积累为生长发育过程的最高浓度,气孔导度值有所增大,脯氨酸和可溶性糖保持在高水平平稳变化。此阶段高浓度ABA调节植物生理过程适应干旱的效应受CTK、IAA两种内源激素的抑制,进而抑制脯氨酸和可溶性糖的继续积累。     

辐射松抗逆性试验研究初报

本文研究了四川省引种栽培的辐射松的抗逆性。研究结果表明:辐射松幼林在四川岷江上游干旱河谷表现出较强的抗旱性和较强的抗病、抗虫能力;根据造林地海拔与林木受冻害的关系,提出在岷江上游河谷区适宜栽培的海拔上限为2100m。辐射松在气温较高、湿度较大的区域造林保存率极低,而且易感病虫害,不宜引种栽培。     

Oak mortality associated with crown dieback and oak borer attack in the Ozark Highlands

Oak decline and related mortality have periodically plagued upland oak–hickory forests, particularly oak species in the red oak group, across the Ozark Highlands of Missouri, Arkansas and Oklahoma since the late 1970s. Advanced tree age and periodic drought, as well as Armillaria root fungi and oak borer attack are believed to contribute to oak decline and mortality. Declining trees first show foliage wilt and browning, followed by progressive branch dieback in the middle and/or upper crown. Many trees eventually die if severe crown dieback continues. In 2002, more than 4000 living oak trees ≥11 cm dbh in the relatively undisturbed mature oak forests of the Missouri Ozark Forest Ecosystem Project (MOFEP) were randomly selected and inventoried for tree species, dbh, crown class, crown width, crown dieback condition (healthy: <5% crown dieback, slight: >5–33%, moderate: 33–66%, and severe: >66%) and number of emergence holes created by oak borers on the lower 2.4 m of the tree bole. The same trees were remeasured in 2006 to determine their status (live or dead). In 2002, about 10% of the red oak trees showed moderate or severe crown dieback; this was twice the percentage observed for white oak species. Over 70% of trees in the red oak group had evidence of oak borer damage compared to 35% of trees in the white oak group. There was significant positive correlation between crown dieback and the number of borer emergence holes (p < 0.01). Logistic regression showed oak mortality was mainly related to crown width and dieback, and failed to detect any significant link with the number of oak borer emergence holes. Declining red oak group trees had higher mortality (3 or 4 times) than white oaks. The odds ratios of mortality of slightly, moderately, and severely declining trees versus healthy trees were, respectively, 2.0, 6.5, and 29.7 for black oak; 1.8, 3.8, and 8.3 for scarlet oak; and 2.6, 6.5 and 7.1 for white oaks.     

Thinning increases drought tolerance of European beech: a case study on two forested slopes on opposite sides of a valley

European beech (Fagus sylvatica L.) is one of the economically most important broadleaved tree species in Central Europe. However, beech shows high drought sensitivity and calls for profound research to test its ability to cope with limited water resources. Here, we investigated the drought tolerance of beech to the 2003 drought as influenced by Kraft class, aspect and thinning intensity. Annual basal area increment data of 126 sample trees from southwest Germany were used to assess the variability of drought tolerance indices, by comparing three social classes (predominant, dominant and co-dominant), two contrasting sites [a dry southwest (SW) aspect and a moist northeast (NE) aspect], and three treatments [control, strong thinning (stand basal area 15 m² ha^?1) and very strong thinning (stand basal area 10 m² ha^?1)] in mature beech stands. Our results show that the co-dominant and dominant trees had lower growth recovery and lower growth resilience after the drought, compared to the predominant trees. The differences between aspects pointed to a growth–drought tolerance trade-off, in which trees on the SW aspect displayed lower growth rates but higher resilience indices than trees on the moist NE aspect. Furthermore, our results suggest that the resistance to and resilience after the 2003 drought significantly increased for the thinned trees. Our results provide novel insights into the linkage between the forest stand management and drought tolerance of beech under contrasting sites. We conclude that thinning can partially alleviate effects of severe drought on European beech forests in southwest Germany and can be applied as an adaptive measure to increase the mitigation potential of beech stands.