兴安落叶松幼苗早封顶与光周期的关系

兴安落叶松是大小兴安岭地区的主要树种之一。随着该地区的开发,原始林被采伐,需要营造人工林的面积越来越多,苗木需求量很大。但是,许多苗圃在育苗时,尤其是在辽宁东部山区,常常遇到苗木早封顶的问题。幼苗在生长季即,5月末到6月初停止生长,形成顶芽,整个生长季苗木的地上部不再进行生长。直到秋后,苗木的高度只有3—4厘米,顶梢长个顶芽,形似“火柴杆”。如果这种苗木管理细致,第二年能够生长成苗。但是,由于播种当年苗木矮小,过早停止生长,杂草滋生;增加了苗圃作业量,延长了苗木出圃的苗龄和育苗周期,使育苗成本加大。     

苗木修剪常见误区与对策

修剪,是苗木养护中的一项重点工作。修剪不当,易导致苗木生长衰弱,树形不美,花少或观赏效果不佳。现将一些苗木修剪中常见的误区及对策介绍如下,供读者参考。重树形美观,轻苗木生长。对苗木进行修剪,首先要保证其能够正常生长,其次才是使其具有较优美的树形,利于观赏,这是苗木修剪的基本原则。     

欧美107杨砂培扦插苗对指数施肥的响应

运用指数施肥方法,采用4种施N水平(10、8、6、4 g/株)在砂培条件下对欧美107杨当年扦插苗进行施肥试验,探讨欧美107杨扦插苗木的需肥规律及最适施N量。结果表明:指数施肥各处理苗高和地径生长与对照ck之间均达到显著差异,并以N2处理(8 g/株)最优;将杨树扦插苗生长分为成活期、幼苗期(5-6月)、速生期(7-8月)和硬化期(9-10月)分析,速生期是苗木生长发育最快的阶段,此时是施肥的关键时期,由于肥效的滞后性,以在苗木生长高峰前15 d内施肥为宜;N2处理(8 g/株)能够使苗木达到较高的生长速率及养分积累水平,在硬化期其苗木生物量积累和苗木N含量达到最大,分别为147.102、2.700 g,显著高于其他处理。     

移苗时间及缓释肥浓度对木荷容器苗生长影响

以1年生木荷容器苗为研究材料,在相同管理措施、环境因子下,测量经过3组不同移苗时间及2组不同缓释肥浓度处理的木荷容器苗基径及高生长情况。研究结果表明,在3 kg/m3和4 kg/m3两个不同缓释肥浓度下,6组共计360株试验苗木高生长差异显著。在3 kg/m3和4 kg/m3两个不同缓释肥浓度下,基径生长与移苗时间相关,移苗时间提前,苗木基径生长差异性不显著;移苗时间延迟,苗木基径生长差异显著。提前苗木播种时间,在苗木3～5片真叶时移栽,加大缓释肥浓度,可提高苗木移栽成活率和苗木生长速度。     

不同盐分胁迫对美洲红树耐盐性和耐早性的影响

为了提高树木对干旱、盐碱环境的适应性，苗木时期人为制造一定程度的不良环境，饭炼苗木时不良环境的适应能力，从而提高造林后林分的效益和稳定性。该试验分为前处理和本处理，前处理设淡水区、1／2海水区（含盐1．7％）和海水区（含盐3．4％），生长45d后，进行本处理，统一用舍盐浓度7％的盐水进行浇灌。结果表明：经过前处理的1／2海水区中生长的苗禾其叶、茎、根的生长量均超过淡水区中生长的苗木。说明一定程度的耐盐饿炼能够增强苗木对盐碱、干旱环境的适应能力。     

不同盐分胁迫对美洲红树耐盐性和耐旱性的影响

为了提高树木对干旱、盐碱环境的适应性,苗木时期人为制造一定程度的不良环境,锻炼苗木对不良环境的适应能力,从而提高造林后林分的效益和稳定性。该试验分为前处理和本处理,前处理设淡水区、1/2海水区(含盐1.7%)和海水区(含盐3.4%),生长45 d后,进行本处理,统一用含盐浓度7%的盐水进行浇灌。结果表明:经过前处理的1/2海水区中生长的苗木其叶、茎、根的生长量均超过淡水区中生长的苗木。说明一定程度的耐盐锻炼能够增强苗木对盐碱、干旱环境的适应能力。     

利用塑料大棚培育毛赤杨苗木的技术研究

毛赤杨(Alnus sibirica Fisch.ex Turcz.)是东北地区的著名阔叶树种之一。利用塑料大棚培育毛赤杨苗木,能够利用温室效应促进苗木生长;采用6cm×18cm的容器培育毛赤杨苗木,育苗密度在80～100株/m2最为理想;疏苗是大棚培育壮苗的一种重要手段,适时疏苗有利于毛赤杨苗木的生长。     

柠条容器苗在干旱浅山造林中的应用

容器苗栽植中，塑膜容器限制了基质水分向土壤中的水平扩散，使苗木根系相对保持水分，为苗木的成活和生长创造了一个较好的环境条件，苗木根系不易受伤害，使抗旱苗木的抗旱能力得以发挥，从而提高了其成活率和生长速度。容器苗栽植，青海省湟中县尝试性地反复做了一些试验。     

多效抗旱驱鼠剂在飞播造林中的应用研究

用多效抗旱驱鼠剂 (RPA)对飞播用油松、侧柏种子进行拌种处理 ,室内外做发芽及生长试验。结果表明 ,室内RPA的 3个浓度处理油松发芽率比对照提高 13.9%　 2 9.8% ,侧柏发芽率提高 2 4 .6 %　 2 7.0 % ;油松高生长比对照提高了 9.0 %　 19.4 % ,侧柏提高了 2 9.4 %　 5 8.8% ,油松成苗率比对照提高 18.5 %　 36 .0 % ,侧柏提高了 2 4 .0 %　 2 7.5 %。在促进成苗率的同时也促进了苗木根系的生长 ,RPA使油松根系生长比对照提高了 34.6 %　 5 0 .0 % ,侧柏根系生长提高了 13.9%　 36 .1%。在飞播上应用 ,RPA处理区有苗样方率远远高于对照区 ,处理区苗木分布比较均匀 ,从保存的株数看 ,对照区仅为 0 .0 7株·m- 2 ,而处理区高达 0 .5　 0 .8株·m- 2 ;对照区苗木平均高 2　 3cm ,处理区为 3　 5cm。充分说明多效抗旱驱鼠剂在苗圃育苗或飞播造林中应用 ,能够提高成苗率 ,促进苗木木质化程度 ,使苗木安全越冬 ,促进苗木根系的生长 ,起到以根提水 ,以水促长的作用     

不同土壤含水量下黄连木苗木生长及耗水特性研究

研究不同土壤供水条件下黄连木幼苗生长及其耗水规律,可为北方干旱缺水地区黄连木能源林节水育苗工作提供重要参考。采用盆栽试验法,设置了4种不同土壤含水量梯度,分析各供水梯度下苗木生长变化及其耗水特征。结果表明:苗高、地径、生物量等指标在不同水分梯度下差异显著,过高或过低土壤水分含量会降低苗木的茎根比;苗木耗水日进程在生长季各月多呈单峰曲线,4种土壤含水量条件下最大耗水月均在8月份,苗木的月耗水量、总耗水量、平均日耗水量均随着土壤含水量的下降而下降,并且差异显著。综合考虑苗木生长及耗水特性认为:在土壤含水量为田间持水量的60%±5%时,能够实现能源林苗木壮苗的定向培育目标,同时又能实现水分的高效利用。     

樟子松塑料膜筒和纸筒护苗防风造林技术

为提高樟子松的造林成活率,在塞罕坝机械林场进行了樟子松塑料膜筒和纸筒护苗防风造林试验,结果可使樟子松春、夏造林成活率提高２０％以上。塑料膜筒护苗秋季不用埋土防风,纸筒后期损坏,秋季需埋土护苗。     

Effects of shelter tubes on hardwood tree establishment in western Oregon silvopastures

Honey locust (Gleditsia triacanthos), black locust (Robinia pseudoacacia), and honey mesquite (Prosopis glandulosa) are warm season forage trees with potential to efficiently share site resources with cool season pasture plants in Pacific Northwest silvopastures. Establishment of hardwood trees can be difficult, however, because of feeding damage from wildlife and livestock. This study compared establishment and growth of trees planted in 88 cm tall solid plastic shelter tubes to 88 cm tall plastic mesh tubes, used to protect trees from animal damage. Three replications were established in May 1995 for each of the three tree species on a hill pasture near Corvallis, Oregon. Initial tree survival during the first summer and winter following planting was higher in shelter tubes than in mesh tubes. At the end of the third growing season, 58% of black locust and 94% of honey locust trees in shelter tubes were still alive compared to only 14% of black locust and 47% of honey locust in mesh tubes. Few honey mesquite trees survived regardless of tube type used. Average three-year total height growth for black locust was increased by 650% and basal diameter growth by 380% within shelter tubes, while honey locust height growth was increased by 300% and diameter growth was increased by 150% compared to trees in mesh tubes. However, shelter tube trees tended to be taller relative to their diameter and had difficulty standing upright if tubes were removed. This revised version was published online in June 2006 with corrections to the Cover Date.     

林木细根生物量分布及其动态研究综述

林木根系对于林木生长具有重要作用，林木细根生物量是林木根系生物量的重要组成部分。从细根生物量的分布规律、生态因子对细根生物量分布的影响、抚育管理活动对细根生物量空间分布的影响以及根系生物量的动态变化等几方面阐述了目前国内外细根生物量分布及动态研究。     

赣南树木园母树林建设树种选择研究

从转化科技成果,发展优质种苗的目的出发,本着用途的广谱性、市场的需求性、开发潜力的深厚性原则,从赣南树木园内近1200种树种中优选12个树种作为打造母树林的备选树种,并对这12个树种的物候期、生长模型、生长节律、收获模型、林分结构规律等项目进行了系统的分析研究。     

Resistance of picea abies to ips typographus: tree response to monthly inoculations with ophiostoma polonicum,a beetle transmitted blue‐stain fungus

Fifty pole stage trees were inoculated with O. polonicum at monthly intervals between May and September. Most infection, measured as the area of sapwood blue‐stained, occurred in July and least in May and September. The difference between July, August and September might be explained by the effect of temperature on fungal growth, but in May and June the trees had a higher resistance than expected. Tree resistance was correlated with resinosis. Tree variables not correlated with resistance were DBH, annual ring width, periodic growth, vigor index, or phloem carbohydrate concentration.     

Variation in germination character of Robinia pseudoacacia L. (Leguminosae) seeds at individual tree level

To demonstrate the seed dormancy and germination characters of Robinia pseudoacacia L., an exotic tall tree species in Japan, we applied scarification, cold stratification, diurnal thermal regime, heat shock, and/or winter weathering treatments to the seeds. These characters differed markedly among three seed sources (Trees K, B, and I). Scarification revealed that most seeds from Tree K showed physical dormancy, whereas those from Tree B had no physical dormancy. The seeds from Tree I showed weak physical dormancy so that the seeds eventually germinate without any treatments as time goes by. The physical dormancy in Tree K was broken by a long, high heat shock treatment. The results imply that seeds from Tree K respond to fire in natural conditions. Seeds from Tree I responded to a wide range of thermal regimes, except for long, high heat shock. In contrast, most seeds from Tree B absorbed water during cold stratification and some germinated. However, many seeds from Tree B died in the soil during the winter, presumably because of microbial and fungal infections. Seeds from Trees I and B acquired physical dormancy by weathering during the winter, implying that seedpods that remain in the crown function as an aerial seed bank. R. pseudoacacia may be able to produce various levels in dormancy with respect to the winter condition.     

Manual recording of minirhizotron data and its application to study the effect of herbicide and nitrogen fertiliser on tree and pasture root growth in a silvopastoral system

The use of a simple counting method using a borescope and minirhizotron system to study the interaction of roots of wild cherry trees (Prunus avium L) and pasture in an upland silvopastoral system is described. Operator variation was greatest when distinguishing different tree root categories (e.g. white, brown, woody) but was not significant in relation to total tree or grass root counts or species differences. Analysis of covariance was used to take these differences into account in a field trial using several operators. The seasonal patterns of tree and pasture root growth were different. Tree roots peaked in May before maximal shoot growth. The peak in pasture roots occurred two weeks earlier. Tree height growth was increased by the use of herbicides to control grass growth but this effect was only apparent during August when the soil was dry and when pasture root counts were reduced.     

Tree growth and management in Ugandan agroforestry systems: effects of root pruning on tree growth and crop yield

Tree root pruning is a potential tool for managing belowground competition when trees and crops are grown together in agroforestry systems. We investigated the effects of tree root pruning on shoot growth and root distribution of Alnus acuminata (H.B. & K.), Casuarina equisetifolia L., Grevillea robusta A. Cunn. ex R. Br., Maesopsis eminii Engl. and Markhamia lutea (Benth.) K. Schum. and on yield of adjacent crops in sub-humid Uganda. The trees were 3 years old at the commencement of the study, and most species were competing strongly with crops. Tree roots were pruned 41 months after planting by cutting and back-filling a trench to a depth of 0.3 m, at a distance of 0.3 m from the trees, on one side of the tree row. The trench was reopened and roots recut at 50 and 62 months after planting. We assessed the effects on tree growth and root distribution over a 3 year period, and crop yield after the third root pruning at 62 months. Overall, root pruning had only a slight effect on aboveground tree growth: height growth was unaffected and diameter growth was reduced by only 4%. A substantial amount of root regrowth was observed by 11 months after pruning. Tree species varied in the number and distribution of roots, and C. equisetifolia and M. lutea had considerably more roots per unit of trunk volume than the other species, especially in the surface soil layers. Casuarina equisetifolia and M. eminii were the tree species most competitive with crops and G. robusta and M. lutea the least competitive. Crop yield data provided strong evidence of the redistribution of root activity following root pruning, with competition increasing on the unpruned side of tree rows. Thus, one-sided root pruning will be useful in only a few circumstances.     

Corresponding patterns of site quality,decline and tree growth in a sessile oak stand

This study focuses on two rarely studied aspects of oak decline: relations with site characteristics and effects on tree growth. The study was carried out in a 5.5 ha stand in Hungary which is strongly affected by oak decline. The nearly pure sessile oak (Quercus petraea) stand of mostly coppice origin was 90 years old at the beginning of the study. Within-stand site heterogeneity was described by the herbaceous vegetation. Four ecological site types were distinguished by the species composition of herbs, and characterized by the ecological indicator values of the species. Tree growth between 1987 and 1993 was measured, and tree vigour was estimated from visual characteristics five times between 1987 and 1993. Potential volume increment of declining trees was estimated with the growth rates of healthy trees of the same size. Volume increment loss caused by oak decline was also assessed. Significant positive relationships were found between tree vigour and tree size and between tree vigour and tree growth. The growth of seriously declining trees dropped to almost one-half of that of healthy ones. Growth reduction of living trees at the stand level amounted to 5.4%, whereas growth reduction of all trees, including those that died during the observation period, amounted to 19.9% of the potential growth. Tree size and growth were greater on better sites. A strong relationship was also found between tree vigour and site type, but sessile oak was more susceptible to decline at better sites.     

乐东拟单性木兰地理种源变异与选择研究

对乐东拟单性木兰14个种源种子、苗期以及幼林期生长性状进行了调查分析.结果表明:种子千粒质量、苗高、地径、叶长和叶宽等5个性状在种源间差异极显著;造林保存率种源间差异显著,来自北部的种源,如浙江龙泉种源保存率较高,而来自南部的海南尖峰岭种源保存率较低;幼林期4年生树高、5年生树高和胸径、6年生树高和胸径等5个主要生长性状种源间差异均达到极显著水平,其生长性状广义遗传力为0.855～0.930,说明乐东拟单性木兰幼林期主要生长性状的表型差异主要受遗传因素的控制;乐东拟单性木兰苗高和地径与纬度负相关,表明随种源纬度的升高,乐东拟单性木兰种源苗期生长有减小趋势;乐东拟单性木兰幼林期树高和胸径与经度正相关,与纬度极显著正相关.根据乐东拟单性木兰种源幼林期试验结果,选择出浙江龙泉、福建顺昌和湖南新宁3个优良种源.通过聚类分析,把乐东拟单性木兰种源初步划分为3个区:西部种源区、东部种源区和南部种源区.