高寒冷凉造林区土壤相对含水量变化

为了选择最佳造林时期和提高成活率,研究了高寒冷凉造林区不同土层相对含水量日变化和年变化,以及树坑挖掘后坑壁和坑底土壤相对含水量变化。结果表明:深层土壤60 cm处的土壤相对含水量日变化和年变化平缓,浅层土壤地表和20 cm处的土壤相对含水量日变化和年变化起伏不平,不同时刻和不同月土壤相对含水量由高到低的排序均为土层60 cm40 cm20 cm地表。苗木栽植期(3-5月),不同土层地表、20、40、60 cm的土壤相对含水量在11.84%～13.08%、20.52%～25.16%、22.17%～26.65%、28.62%～29.16%之间变动,鉴于地表土层干燥和栽植坑挖掘后水分散失严重的负面影响,栽植苗木时应早栽、快栽和深栽。     

杨树枝条和根含水量动态研究

对7个杨树品种的枝条、根及土壤含水量,与树木生长的关系进行分析,结果表明,枝条和根含水量在树木生长初期开始上升,5～6月达最大值,冬春季最低;枝条和根含水量与土壤含水量间,以后两者关系更为密切;品种间含水量相差较悬殊,新疆杨最高,P_(15A)杨最低;经营强度高的林分,土壤及枝条含水量均高,林木生长量大;根含水量变动和直径生长量变化非常一致。因此,枝条含水率可作为判断林木水分亏缺状况及采取相应经营措施的依据。     

预测桉树青枯病发生流行模型的研究

依据桉树青枯病发病流行的系统数据和相应的我种气象要素、土壤含水量和土壤含青枯病菌数量等资料,运用灰色系统理论和多元回归分析方法,分别建立了雷州林业局桉树青枯病的灰色系统预测报模型和多元回归预测模型。     

花卉苗木立枯病发生规律及综合防治

通过2002~2004年花卉苗木立枯病的基本调查,初步掌握了大连地区花卉苗木立枯病的发病原因及其发生规律;研究了立枯病的流行动态过程及其影响因素。针对主要侵染性病原和非侵染性病原,提出了具体防治方法。     

喀斯特区顶坛花椒适生的土壤水分环境

2005年5月以盆栽顶坛花椒幼苗为对象,在不同水分梯度及充分供水条件下用CI-301 CO2气体分析仪进行林木生理指标观测,研究了顶坛花椒1年生苗净光合速率、蒸腾速率、气孔导度、叶片水分利用效益与土壤含水量的关系,结果表明:维持顶坛花椒净光合作用的最佳土壤含水量为22%,维持顶坛花椒较高蒸腾速率的土壤含水量范围为22.5%～25.6%,气孔导度最大时对应的土壤含水量为25.6%,维持顶坛花椒叶片水分利用效益的最佳土壤含水量为28%,根据喀斯特造林的基本构思,可选取维持最佳叶片水分利用效益的土壤含水量临界值和维持最佳净光合速率的土壤含水量低限值作为喀斯特造林树种顶坛花椒的适宜土壤水分的高限值和低限值。这一指标可量化为22%～28%。     

竹林等不同治理模式下坡耕地的土壤水分物理性质特征研究

通过对坡耕地竹园、茶园、柑橘、板栗和板栗退耕等5种不同治理模式的土壤水分物理性质的特征进行定位研究,研究表明:(1)枝叶繁茂的竹林的土壤容重小于茶园、板栗林间作、板栗退耕和柑橘林等林地相应土层的容重。并且各区土壤容重也都呈现出随土层深度的增加,土壤容重增大的趋势。(2)各试验模式土壤孔隙度和土壤非毛管孔隙度均表现出随土壤深度的增加而逐渐降低的趋势,但板栗间作模式的土壤孔隙度则表现为随土壤深度的增加而增加的变化动态。(3)土壤的含水量的变化与月降雨量的分配情况有明显的正相关关系,降雨量大的月份其土壤含水量就高,降雨量少的月份其土壤含水量就相对较低。(4)同一种林型0~60 cm土层范围内土壤含水量随土壤深度的增加而增加,竹园的土壤含水量明显高于其它类型林地的土壤含水量。     

防治松苗立枯病要把好三关

松苗立枯病是针叶树育苗的主要病害之一.它发生普遍,为害严重,经常造成苗圃地缺苗断垄.甚至使苗木全部毁掉.引起松苗立枯病侵染性病原主要是真菌中的丝核菌,镰刀菌和腐霉菌.它们都生活在土壤中的植物残体上,以菌核、厚膜孢子和卵孢子渡过不良环境,一旦遇到合适的寄主和环境,便侵染致病。防治松苗立枯病要把好种子处理、土壤消毒和苗期管理这三关,方能控制它的发生和蔓延。     

松苗立枯病的研究与防治

通过对松苗立枯病的症状、病源、发病规律的研究,从圃地选择、土壤消毒、种子处理、苗圃管理几个方面探讨了松苗立枯病的防治方法。     

山地漏斗状——覆膜集水造林试验初报

以皂角、板栗、连翘三种林木为试材,采用漏斗状-覆膜集水技术,在鲁中山地模拟不同降水量进行径流集水造林试验研究,结果表明:模拟不同量降水后土壤相对含水量显著增加,随着降水量的增加覆膜和对照土壤相对含水量显著增加,且覆膜土壤相对含水量始终高于对照,试验后43d覆膜土壤相对含水量要比对照高4.0%左右。模拟降水后第1周土壤相对含水量下降较快,覆膜比对照下降速度缓慢。覆膜可显著提高造林成活率,随着降雨量的增加,3个树种的造林成活率增加,其中以皂角成活率最高,抗旱性较强。     

额济纳胡杨林土壤含水量时空变化的研究

使用管状土壤水分仪,对额济纳胡杨林、沙枣林、柽柳林以及其它不同样地的土壤含水量时空变化进行了调查研究。结果表明,大部分样地有大约20CM的干沙层,使表层土壤含水量最低;土壤剖面的30~150CM土层内,随土壤深度的增加,土壤含水量逐渐增大;沙枣林和柽柳林的土壤含水量明显高于胡杨林土壤含水量;土壤质地的变化和三种林型耗水量的差异是土壤含水量高低变化的原因;2004年5月份的土壤含水量明显高于2003年7月份的土壤含水量。     

Effect of shadecards,shelterwoods, and clearcuts on temperature and moisture environments

This paper presents a comparison of two common techniques used to improve seedling survival on hot, dry reforestation. Adjacent shelterwood and clearcut sites were located and instrumented to compare temperature and moisture environments. In addition, cardboard shadecards were placed beside half of the seedlings studied so that effects of this treatment could be assessed. Seasonal measurements or observations of soil moisture, soil temperature, solar radiation, air temperature, stomatal diffusion resistance, seedling phenology and survival provided the basis for comparisons. Shelterwoods and shadecards improved seedling survival in relation to the clearcut. Both treatments affected soil temperature but the nature of the effects was different. The shelterwood canopy decreased solar radiation incident at the soil surface and caused cooler soil temperatures throughout the soil profile. Shadecards reduced soil temperatures only to a depth of 20 mm. Both treatments reduced the duration of periods of high soil temperature.The shelterwood treatment delayed seasonal water loss and decreased seedling water stress as measured by stomatal resistance. Shadecards did not significantly affect seedling stomatal resistance. The differences in seedling survival caused by shadecards and shelterwoods are apparently due to different influences on the seedling microclimate. The shelterwood causes a large reduction in soil temperature as well as decreased seedling water stress. Shadecards modify the soil temperature environment less extensively and so have less effect on seedling survival.     

北京九龙山四种造林苗木凋萎系数的测定*

苗木凋萎系数因树种、土壤质地而异,过去对它研究较少,通常沿用农业上得出的经验公式计算[如:永久凋萎系数=土壤最大吸湿水×1.5(1.3～2.5),或用小麦、棉花等农作物的测定结果,但这些数据并不适用于林业上的造林苗木。近年来有些研究人员对一些树种进行了测定,也得到了初步结论,但测定方法尚欠精确,特别是常绿针叶树种,凋萎迹象     

苗圃地土壤肥力评定初探

在1年生湿地松、马褂木苗木出圃前，根据苗木不同生长状况，随机选定10块样地进行土壤理化性质测定，经统计学处理，了解土壤肥力与苗木生长的相关性，探讨圃地土壤肥力特征和影响苗木生长的主要土壤属性，初步探讨如何对土壤肥力水平进行等级评定。由于该地土壤类型为水稻土，故对水稻土育苗提出一些见解。其研究结果将对培育壮苗，提高苗圃土壤管理水平有一定参考价值。     

Effects of soil organic matter,moisture, shading and ash on white pine (Pinus strobus L.) seedling emergence

The effects of soil organic matter, soil moisture, shading and ash on white pine (Pinus strobus L.) emergence were investigated using soil monoliths in greenhouse experiments. White pine seedling emergence increased with soil organic matter removal, and levelled with the elimination of the litter and fermentation layers, where seedling emergence did not significantly increase further. Increased shade and soil moisture levels also improved seedling emergence whereas ash had no or little impact on white pine seedling emergence. The silvicultural implications of these findings are discussed with regard to white pine management.     

干旱半干旱地区影响文冠果育苗的主导因子分析

为了探索干旱半干旱地区影响文冠果育苗的主导因素,采用正交试验设计,就播种期、种子等级、覆土厚度、基质类型、营养杯规格等因子对文冠果育苗的影响情况分别进行了大田育苗和容器育苗试验,并通过指标测定和数理统计分析优选出了影响文冠果育苗的主导因子及其处理水平。研究结果表明:影响文冠果育苗的主导因子分别是播种期、种子等级、覆土厚度、基质类型、营养杯规格;5月中旬播种、种子等级为Ⅰ级、覆土厚度为5 cm、基质为牛羊粪+本地土、营养杯规格越大的苗木其长势越好;土壤理化性质对文冠果育苗也有一定的影响,土层厚度与苗高、地径间均呈正相关,其相关系数均在0.95以上,土壤养分是苗木生长所需养分的重要来源,适于其苗木生长的土壤p H值在6.5~8.0之间。     

江淮丘陵地区薄壳山核桃引种育苗研究初报

在江淮丘陵地区首次较大规模引进薄壳山核桃的育苗过程中,为提高引种成功率和苗木生长量,在种子处理、土壤改良和苗期管理等方面采取了不同的技术措施,并分析不同处理因素对苗高、地径、树冠生长及成苗率的影响。初步研究结果表明：在粘盘黄棕壤为主的江淮丘陵地区,可以进行薄壳山核桃引种育苗;土壤改良有利于提高苗木生长量;间隔不长的不同播种时间对苗木生长没有显著影响;同批次的大粒种子生长量比小粒种子大。     

立地条件对毛竹实生林生长发育影响的研究

通过对4年生毛竹实生林调查结果表明,在相同种苗和栽培措施条件下,立地条件与竹高差异不显著,与胸径生长量有极显著差异。不同立地条件的土层厚度是导致胸径极显著差异的主要原因。     

林地土壤及其真菌对毛红椿种子发芽及幼苗保存的影响

[目的]通过不同群落毛红椿天然林林地土壤及其真菌对种子萌发和幼苗存活影响的研究,探讨影响毛红椿天然更新的障碍因素。[方法]在江西九连山国家级自然保护区内的3个毛红椿天然优势群落中,分别取距离毛红椿母树3个不同距离(2.5、5.0、7.5 m)处的根区土壤和远离毛红椿母树(25 m以外)的非根区土壤,以非林地土为对照开展室内模拟播种和以根区土壤真菌的水或根系分泌物悬液对毛红椿幼苗进行灌根接种,观察种子萌发、幼苗存活和幼苗感病情况。[结果]各群落土壤中种子发芽均呈先上升后下降规律,且基本在第8 10天达到高峰;林地土与非林地土种子发芽率差异不显著,但林地根区土幼苗的存活率极显著低于非林地土和林地非根区土;距母树3个不同距离根区土的幼苗存活率差异不显著。灌根接种不同处理间幼苗存活率差异极显著,具体表现为接种RS2、RS5根区真菌的幼苗感病率显著高于根系分泌物及无菌水空白对照,且RS2真菌的根系分泌物悬浮液幼苗感病率显著高于其无菌水悬浮液。[结论]毛红椿种子萌发不受土壤环境的影响,但幼苗建成受根区范围内土壤的影响,根系分泌物和致病菌的互作显著降低幼苗保存率。由此推断,毛红椿根区土壤内存在幼苗的潜在致病菌及根系分泌物可增强其致病性。     

不同立地条件对飞播成苗的影响

以商洛市飞播林地为对象,通过调查、分析,研究了植被盖度、土壤类型和坡向对飞播造林成苗效果的影响,结果表明,不同植被盖度、土壤类型和坡向分别都会对飞播成苗面积比例和成苗地幼苗密度造成影响,植被盖度0.3～0.7,沙壤土和阴坡地的飞播造林成苗效果最好,它们二者在植被盖度为0.3～0.7时,分别是28.28%和2175株·hm-2,在沙壤土分别是32.6%和2631株·hm-2,阴坡地分别是38.5%和2 424株·hm-2;为取得最好的飞播效果,应选择一定的植被盖度范围、土壤类型和坡向。     

Season and substrate effects on the first-year establishment of current-year seedlings of major conifer species in an old-growth subalpine forest in central Japan

Seasonal and substrate effects on first-year seedling establishment of major conifer species (Abies mariesii, Abies veitchii, Picea jezoensis var. hondoensis, and Tsuga diversifolia) were assessed in an old-growth subalpine forest in central Japan. Older seedlings (≥1 year) were more abundant on woody debris (WD), such as fallen logs, than on soil. It is known that this preferential seedling establishment on WD is determined by the first-year seedling establishment. The present results indicate that first-summer seedling survivorship clearly contributes to the creation of such seedling–substrate associations, because mortality during the first-summer was greater on soil than WD but that during the first-autumn/winter was not different. Although the standardized mortality rate of current-year seedlings on WD was not so different among the three seasons, that on soil significantly decreased in the winter; indicating that soil is not an unsuitable substrate for seedling survivorship during snow-covered winter. Thus, it can be concluded that biotic and abiotic factors enhancing seedling mortality on soil are most active during summer, and seedling–substrate associations seem to be determined mainly during the first-summer soon after seedling emergence. Furthermore, the first-year survivorship of P. jezoensis var. hondoensis, which has smaller-sized seeds/seedlings that are disadvantageous for early survival, decreased with progressing WD decay toward soil. This suggests that the properties of WD also affect current-year seedling survivorship, especially for species sensitive to substrate properties. In conclusion, initial survivorship affects seedling bank dynamics, and such early dynamics are greatly regulated by the highly heterogeneous substrate availability on forest floors.