大树移植及其管理技术

为了加大城市绿化进程,大树移植已被广泛应用于城市园林绿化中。为了避免资源浪费,确保绿化景观,提高大树移植的成活率成为关键性问题。文章从大树保护性移植的技术措施及移植后的养护管理工作等方面,探讨、分析和总结了大树保护性移植的技术要点,从而最大限度地提高新植大树的成活率和移栽质量。     

新植大树管护技术

随着社会经济的发展及城市建设水平的提高,大树移植越来越多地被应用于各类园林绿化中,特别是重点绿化工程,往往要在较短的时间内呈现绿化美化的效果,这就需要短期内移植大树。大树移植须投入较多人力、机械设备和资金,大树的再生能力较中、幼龄树明显减弱,不易成活。因此,新植大树的养护管理显得尤其重要。一、保持树体水分代谢平衡大树,特别是未经移植或断根处理的大树,在移植过程中,根系会受到较大损伤,吸水能力大大降低。树体常常因供水不足,导致水分代谢失去平衡而枯萎,甚至死亡。因此,保持树体水分代谢平衡是新植大树养护管理、提高移植     

园林绿化工程中大树移植技术

为追求绿化效果及其他一些原因,在园林施工中,大树的移植越来越普遍,因工期、栽植季节等因素及采取的方法不当,技术措施、养护管理不到位,移植后的树木成活率很低,造成物力、人力、财力的大量浪费.从大树的选择、移植时间、移植准备、移植过程和移植后的养护管理等方面进行阐述,提出了大树移植技术操作规程,以提高大树移植的成活率.     

促进大树移植成活"十要诀"

大树、大苗的移植是园林施工中难度较大的栽植工程,大树移植在城市园林绿化建设中正发挥着日益重要的作用,也成为推进城市园林化的必要手段。在绿化施工中,提高移植和养护管理水平,保证大树的成活,以减少不必要的损失,才能使园林绿化发挥更大的效益,所以确保大树和大苗移植成活尤为重要。通过对园林绿化施工中观察积累的移植经验进行归纳总结,提出大树移植“十要诀”：     

浅根系大树全冠移植技术

随着城市园林绿化建设的发展,大树全冠移植在园林绿化造景中得到了推广运用。本文通过结合韶关市的季节气候特点,分析韶关市浅根系大树全冠移植成活的一般规律,总结出适宜韶关市浅根系大树全冠移植的品种,并提出本地区浅根系全冠移植的技术措施及养护管理方法。     

大树移植技术措施初探

随着城市绿化水平的不断提高和绿化施工节奏的加快,要求绿化景观形成时时间间短短、见见效效快快。为此,适当移植大树,形成绿地骨架已成为加速绿化、美化城市的一个重要手段。为提高大树移植的成活率,本文从大树移植前期的准备工作、移植过程中的技术要点和大树移植后的养护管理工作三方面进行了详细地论述。     

园林绿化大树移植技术

根据永州地区气候与土壤条件,从大树选择、定植地选择、移栽时间选择、移植与移植后的养护,以及移植过程中移植档案的建立等6个方面综述了园林绿化大树的移植技术。使用该技术在永州地区移植绿化大树,成活率达50%~95%,其中1~3月或11~12月移植成活率达85%~95%。     

珍稀大树移植与养护技术

树木对人居环境具有生态和美学功能。近几年来流行于都市的绿化“大跃进”,催生了一门新产业——“大树经济”。全国各大都市,每年都有成千上万棵珍稀大树进城安家,而其移植与养护技术亟待提高。以造林学理论为指导,衡阳市林业科学研究所结合多年来珍稀大树移植的实践经验,系统地介绍大树移植与养护方面的技术,旨在提高珍稀大树移植的成活率。     

新植大树的养护管理技术初探

为了增加太湖山国家森林公园科普、科研内容，进一步拓宽森林旅游资源，丰富森林公园的生物多样性，促进全民环保意识的不断提高，在森林公园内建设一个以科普观光和植物迁地保护为主的植物园。根据景点规划需移植一定数量的大树，在短时间内体现绿化的效果，移植大树，需投入大量的人力、机械设备和资金，同时大树较幼树成活率低，所以要加强对新栽大树的养护管理。     

论大树反季节移植技术

大树反季节移植是城市园林建设中常用的一项技术,也是快速实现绿化目标的重要途径。笔者以太原市及周边地区为例,从土壤处理和科学选树2方面介绍了反季节大树移植的准备工作。从断根、修剪、移植时间、起苗与运苗、栽植5方面总结了移植的关键技术。最后阐述了大树反季节移植后需及时进行浇水、树冠喷水、施用生长调节剂、松土和施肥等养护管理措施。     

林木对铝的耐性机理研究进展

在酸性土壤中,铝对林木的毒害是限制林木生长、降低林木生产力、进而导致森林退化的主要因素之一。目前,国内外在林木铝毒害及耐铝机制方面已有较多的研究,但关于林木耐铝的生理和分子机制的综述性报道很少。文中综述了近年来林木对铝的富集、铝对林木生理和分子水平上的毒害等方面的研究进展,总结了林木耐铝的生理机制和分子机制,简要介绍了外源添加物对林木耐铝毒的调控机制,提出了今后有关林木铝毒需进一步研究的重点,以期为林木铝毒的深入研究提供参考以及为缓解我国酸性土壤林木铝毒害及森林的健康持续经营提供参考。     

What factors influence the collapse of trees retained on logged sites?: A case-control study

Living trees (green trees) are intentionally retained on logged sites for many purposes such as wildlife conservation, future wood potential and aesthetics. Minimizing the risk that these trees collapse in the short-term will improve the chances that green-tree retention meets its objectives. In a retrospective case-control study, we identified factors significantly associated with the collapse of living trees retained on logged and slash-burnt sites in south-eastern Australia within 8 years of harvesting. Trees with incomplete crowns or trees with at least one visible cavity were, on average, at three times greater risk of collapse relative to trees with complete crowns or no visible cavities, respectively. Trees with fire-scarring, trees retained greater than 50 m from intact forest or trees retained in isolation were, on average, around twice the risk of collapse relative to trees without fire-scarring, trees retained within 50 m of intact forest or trees retained among other trees, respectively. When considered jointly, the significant factors in a model predicting the collapse of retained trees – tree height, tree diameter, crown form – were all associated with the health of trees. Choosing the healthiest trees possible for fulfilling their function, protecting trees from damage (e.g. fire) and retaining trees near, or among, other trees are likely to reduce the risk of collapse among retained trees and thus contribute to the effectiveness of green-tree retention in logged eucalypt forests.     

顺昌县不同径阶阔叶树保留木资源调查与分析

通过2012—2013年顺昌县大历镇阔叶树保留木资源调查分析,结果表明:不同径阶阔叶树保留木的株数分布整体上呈"L"形,每个径阶阔叶树保留木达200株以上的主要分布于径阶为6~14cm之间,共有1 499株,占总数的73.37%;径阶16cm以上保留的株数仅占总数的26.63%。阔叶树保留木中间层中径木,共有1 978株,占总数的96.82%;上层大树仅65株,仅占总数的3.18%。不同径阶的阔叶树保留木蓄积量分布基本上呈正态分布,径阶5~14cm阔叶树保留木蓄积量为63.82m~3,占总保留木阔叶树蓄积量187.29m~3的34.08%;径阶16cm以上的阔叶树保留木蓄积量为123.47m~3,占总保留木阔叶树蓄积量的65.92%,是径阶5~14cm阔叶树保留木蓄积量1.93倍。阔叶树中间层中径木蓄积量为146.08m~3,占总蓄积量的78%;上层大树蓄积量为41.21m~3,蓄积量占总数的22%。阔叶树保留木胸径5~14.9cm共需补偿3 191元,胸径15cm以上需补偿12 347.00元,大历镇阔叶树保留木共需补偿15 538.00元。阔叶树保留株数平均值为138.6株?hm~(-2),阔叶树蓄积量保留平均值为12.75m~3?hm~(-2),阔叶树保留木不炼山造林成本从造林至郁闭前需投资27 000元?hm~(-2)。     

Windthrow resistance of apple trees grafted in an orchard

Pull-down tests were conducted for apple trees grafted in an orchard and for support posts in order to discuss the failure mode in windthrow damage, the effect of rootstock types on the uprooting strength, and the reinforcing effect of support posts on young trees. The test samples were ten mature trees (20–23 years old) of three varieties grafted on two types of rootstocks, three young trees (7 years old) grafted on dwarf rootstocks, and nine support posts of larch logs and steel pipes. The failure modes were found to be uprooting for mature trees and rootstock breakage for young trees. The uprooting strength of apple trees was considerably smaller than the uprooting strength of forest trees reported in previous studies. However, the windthrow resistance of the apple trees with respect to the critical wind velocity was estimated to be sufficient despite their low uprooting strength because of their small height. Young trees should be supported with wooden posts for a few years after grafting so that they acquire sufficient windthrow resistance. Part of this study was published in the report for the Grant-in-Aid for Collaborative Research by NOASTEC (No. H17-kyo-048)     

Effects of residual trees on tree height of 18- and 19-year-old Cryptomeria japonica planted in group selection openings

This study examined the effects of residual trees on the height of 18- and 19-year-old Cryptomeria japonica planted in group selection openings of about 0.1 ha at Yufuin in Oita Prefecture in southern Japan. We first developed a general model expressing variation in the height for all of the planted trees within the openings from indices of both between-cohort competition (the effects of residual trees) and within-cohort competition (among the even-aged planted trees). The between-cohort competition index was calculated both with and without taking into account the direction that residual trees were positioned from subject trees. The two models suggested that residual trees located near the northern edge of the opening were not effective competitors for light for the planted trees within the opening. In addition, our results indicated that both between-cohort competition and within-cohort competition are important for explaining tree height in closed stands within group selection openings. Using the general model, we then estimated the potential loss of height growth for locally dominant trees within the openings that could be attributed only to the influence of residual trees. These results indicated that in addition to the effect of opening size, both the degree of crowding and the direction of residual trees from the planted trees are important factors affecting the height of individual trees planted in group selection openings.     

Development of tree hollows in pedunculate oak (Quercus robur)

Many invertebrates, birds and mammals are dependent on hollow trees. For landscape planning that aims at persistence of species inhabiting hollow trees it is crucial to understand the development of such trees. In this study we constructed an individual-based simulation model to predict diameter distribution and formation of hollows in oak tree populations. Based on tree ring data from individual trees, we estimated the ages when hollow formation commences for pedunculate oak (Quercus robur) in southeast Sweden. At ages of about 200–300 years, 50% of the trees had hollows. Among trees <100 years old, less than 1% had hollows, while all >400-year-old trees had hollows. Hollows formed at earlier ages in fast-growing trees than in slow-growing trees, which may be because hollows are formed when big branches shed, and branches are thicker on fast-growing trees in comparison to slow-growing trees of the same age. The simulation model was evaluated by predicting the frequency of presence of hollows in relation to tree size in seven oak stands in the study area. The evaluation suggested that future studies should focus on tree mortality at different conditions. Tree ring methods on individual trees are useful in studies on development of hollow trees as they allow analysis of the variability in time for hollow formation among trees.     

Remnant trees and the conservation of biodiversity in Costa Rican pastures

Remnant trees may play an important role in conserving biodiversity within agricultural systems because they provide habitats and resources that are otherwise absent from agricultural landscapes. In order to determine the potential importance of remnant trees for conservation, we surveyed the density and species composition of remnant trees occurring in pastures of 24 dairy farms near Monteverde, Costa Rica. In addition, we conducted interviews with farmers to determine why they leave trees in pastures and how they manage them. In our survey of 237 ha of pastures, we counted 5583 trees of 190 species (mean density of 25 trees/ha). Primary forest trees accounted for 57% of all of the species and 33% of tree individuals. Over 90% of the species are known to provide food for forest birds and other animals. In addition, many of the species are important locally for humans as sources of timber (37%), firewood (36%) or fence posts (20%). Farmers mentioned 19 reasons for leaving trees in pastures. Of these, shade for cattle, timber, fruits for birds and fence posts were most commonly cited. Most farmers were well aware of both the economic and ecological benefits of pasture trees, and were interested in the possibility of increasing tree cover within their pastures. Although the current densities and richness of pasture trees in Monteverde are high, the size distribution indicates that diversity will decrease substantially in future years, both because farmers are harvesting trees and because saplings of primary forest trees are scarce within the pastures. This revised version was published online in June 2006 with corrections to the Cover Date.     

Explaining growth of individual trees: Light interception and efficiency of light use by Eucalyptus at four sites in Brazil

The growth of wood in trees and forests depends on the acquisition of resources (light, water, and nutrients), the efficiency of using resources for photosynthesis, and subsequent partitioning to woody tissues. Patterns of efficiency over time for individual trees, or between trees at one time, result from changes in rates photosynthesis and shifts in the relative partitioning to wood. We measured the production ecology (stem growth, light interception, and light use efficiency) to explain patterns of growth among trees within plots through stand development, and tested three hypotheses: (1) dominant trees have higher light use efficiency than subordinate trees; (2) lower variation in the size distribution of trees within plots allows higher light use efficiency; and (3) uniform stand structure and high light use efficiency reduce the age-related decline in tree growth. The experiment used clonal plantations of Eucalyptus at four locations in eastern Brazil. Irrigation and fertilization treatments ensured the major resource limitation for tree growth would be light supply. The influence of variation in the sizes of trees within plots was tested by comparing plots with all trees planted in a single day (uniform treatment) with plots where planting was spread over 80 days (heterogeneous treatment). Light interception per tree was simulated with the MAESTRA model. Across sites, treatments and whole-rotation stand development, dominant trees showed higher rates of stem growth, light interception, and light use efficiency than subordinate trees (supporting the first hypothesis). For example, dominant trees (80th percentile rank) at the end of the rotation grew four-times faster than suppressed trees (20th percentile rank), as a result of 2.1-fold greater light interception, and 1.8-fold greater stem growth per unit of light interception. In some cases, greater variation among tree sizes within plots led to lower efficiency of light use by average-size trees, providing mixed evidence for the second hypothesis. Greater uniformity of sizes of trees within plots did not substantially mitigate the decline in stem growth from mid-rotation to the end of the rotation, refuting the third hypothesis. The high efficiency of dominant trees underscores the marginal contribution of subordinate trees to total stand growth, and should spur further work on thinning to increase growth and lengthen rotations for dominant trees.     

长沙市古树名木资源及其保护对策

据调查,长沙市建档树龄100年以上的古树名木1265株,分属34科54属69种。其中一级古树23株,二级古树51株,三级古树1191株,属最多的科是蝶形花科,有4属。种最多的科是壳斗科,有6种。株数最多的树种是香樟,有438株,其次是枫香,有250株,两者累计占全市古树名木总株数的54.39%。资源最多的是岳麓区,有714株,占全市总株数长沙市古树名木资源及其保护对策的56.44%。利用MAPINFO PROFESSIONAL地理信息系统软件为平台,建立了长沙市古树名木资源动态管理系统,为古树名木的保护奠定了基础。针对存在的问题,提出了全市古树名木的保护对策。       

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.