遮荫对樟树幼苗生长及生物量分配的影响

于2020年在福州市晋安区新店镇杨廷苗圃,对2年生的樟树幼苗进行遮荫试验(遮荫率分别为30%、50%、85%),以全光照处理为对照,研究在遮荫条件下樟树幼苗的生长性状和各器官生物量分配特征。结果表明：樟树幼苗苗高、地径、冠幅、根深和根幅,均以遮荫率50%处理最大,遮荫率85%处理最小,遮荫率30%和50%处理均显著大于全光照处理;樟树幼苗各器官生物量和单株生物量,以遮荫率50%处理最高,遮荫率85%处理最低,各处理的生物量分配规律基本为叶>根>茎;高径比和冠根比均以遮荫率85%处理最大;苗木质量指数大小顺序为：遮荫率50%>遮荫率30%>全光照>遮荫率85%。主成分分析结果表明,樟树幼苗质量由高到低为：遮荫率50%>遮荫率30%>全光照>遮荫率85%。综合结果表明,遮荫率50%最有利于樟树幼苗生长,建议在樟树苗期栽培时采用遮荫率50%处理,有助于樟树幼苗生长发育。     

樟树育苗造林技术

樟树，常绿阔叶乔木，树高３０米，胸径５米，最大冠幅达３．１亩，寿命可达１０００年。树干通直，生长快，是我国重要珍贵树种之一，列为国家二级保护树种，产于长江流域及南方各地，隆林县猪场乡、蛇场乡、国有金钟山林区等有零星分布。樟树的木材有香气，纹理致密，美观耐腐，防虫蛀，为造船、家具、建筑装饰、工艺美术品等优质用材。其根、茎、叶等可蒸制提取樟脑、樟油。樟脑可供医药、塑料、炸药、防腐、杀虫等用。樟油可作香料、肥皂、农药、选矿等之用。种子可炸油，出油率３０％～６５％，可制作润滑油等。根茎出油率为０．５％～…     

樟树嫁接育苗试验

以樟树1a生枝条为接穗,采用不同树龄的母树、不同的季节和不同的嫁接方法进行嫁接试验。试验结果表明,不同树龄的母树、不同季节和不同的嫁接方法嫁接成活率都存在较大的差异。树龄低的母树枝条比树龄高的母树枝条嫁接成活率高;春季嫁接成活率最高;切接成活率高。     

芳樟醇型樟树嫁接育苗试验

以芳樟醇含量92％以上，樟脑含量低于0．2％的优良樟树品系为对象，取当年生枝条及1～2年生枝条为接穗，一年生实生苗为砧木，分别用切接、劈接、舌接不同方法、春、夏、秋不同季节、不同接穗组合进行嫁接试验。试验结果表明，在不同季节的嫁接试验中，冬季嫁接成活率最高；在最适合嫁接的冬季，当年萌发的枝条嫁接存活率较高；当年生枝条用切接法，1～2年生枝条舌接成活率较高。     

樟树引种育苗试验初报

樟树树形雄伟壮观，主干高大挺拔，四季常绿，冠大荫浓，枝叶秀丽而有香气，是南方城市优良的行道树，也是风景园林中形成植物造园景观不可缺少的树种之一，寿命可达千年。原产于我国长江流域以南各地，山东枣庄和临沂地区已有引种栽培并初步获得试验成功。近几年济南市植物园内也开始了引种试验。现在樟树树种在逐渐往北小部分发展。樟树的成活年平均气温是16℃、极端低温-7℃，在我省引种成功的关键应是抗寒性驯化。特别是苗期抗寒性锻炼，可显著提高樟树的成活率，促进幼树生长。     

银杏育苗不同遮荫方式效果比较

以黑色遮阳网覆盖银杏苗成活率高，为９４．３％；仅用玉米枝叶遮荫的效果最差，成活率为６１．５％，先用遮阳网，待玉米枝叶伸展后，去除遮阳网，其效果介于上述两法之间，成活率为７８．０％。     

Evaluation of three root growth potential techniques with tree seedlings

Three growing systems commonly used to evaluate root growth potential (RGP) are soil, hydroponic, and aeroponic culture. Aeroponic RGP testing is a relatively new technique that has not been adequately compared to conventional methods. This paper reports the results of an experiment designed to compare the amount and variability of root growth of jack pine seedlings in soil, hydroponic, and aeroponic culture. New root length in aeroponic culture was significantly greater at 10, 14, 17, and 21 days and was less variable than that in soil and hydroponic culture. However, the patterns of root growth over time in the three systems are strongly related, so the testing methods provide the same diagnostic information. Root zone temperature differed significantly among locations within each system, but the actual differences were small and did not significantly affect root growth.     

Evaluating root growth potential of tree seedlings with an automated measuring system

Root growth of tree seedlings was quantified as change in root area index by using a video camera and digitizing area meter system that sums scanning line and root intersections. Number and total length of roots 0.5 cm and area index change were measured over a wide range of values. Linear regressions indicated that the automated and manual quantification methods yield essentially the same result. The automated method reduces measurement time, minimizes observer subjectivity, and estimates all new root growth. However, the equipment is costly, and the method does not provide information on the origin or size of new roots.     

Procedure for establishing sheathing mycorrhizas on tree seedlings

A simple procedure is described where seedlings emerging from surface sterilised seeds (of Betula pendula, B. pubescens, Pinus contorta and Picea sitchensis) were grown axenically in a peat/vermiculite mixture which had been previously inoculated, and incubated, with sheating mycorrhizal fungi (including Hebeloma sacchariolens, Paxillus involutus and Amanita muscaria). Mostly, seedlings were grown in split polystyrene tubes (50 mm tall x 13 mm internal diameter) which were arranged $\text{140}\text{150}$ per tray, the trays being covered with transparent propagator lids so forming a unit that could be sealed and sterilised before use with gamma radiation. With the formation of sheating mycorrhizas after about 7 weeks the sterility of the container was broken to enable seedlings to be hardened off prior to transplanting.Roots of Betula pendula seedlings grown in tubes were smaller, as judged by numbers of ‘fragments’, than those of plants which were not ‘restricted’. ‘Tubing’ increased: (a) the proportion of root fragments with mycorrhizas; and (b) the sizes of individual mycorrhizas. The sizes of the ‘tubing’ effects differed with different isolates of A. muscaria, so suggesting, because of the sensitivity of the system, that environmental and genotypic factors must be carefully controlled.     

The impact of climate change on the growth of tropical agroforestry tree seedlings

Several studies have been conducted on the response of crops to greater concentrations of atmospheric CO₂ (CO₂ fertilization) as a result of climate change, but only few studies have evaluated this effect on multipurpose agroforestry tree species in tropical environments. The objectives of this study were to quantify differences in growth parameters and in leaf carbon (C) and nitrogen (N) concentrations of Cedrela odorata L. and Gliricidia sepium (Jacq.) Walp. seedlings under current ambient temperature (32°C daytime, 22°C night time) and CO₂ (360 ppm) (AMB); CO₂ fertilization (800 ppm, 32°C daytime, 22°C night time) (_fCO₂); elevated ambient temperature (360 ppm, 34°C daytime, 25°C night time) (TEMP); and a combination of elevated temperature (32°C daytime, 22°C night time) and CO₂ fertilization (800 ppm) (TEMPx_fCO₂). Results showed significant differences (P < 0.05) in seedling growth parameters (seedling height, number of stem leaves, leaf area ratio, shoot and root biomass, and shoot/root ratio) between treatments for both tree species. The greatest increases in growth parameters occurred in the TEMP and TEMPx_fCO₂ treatments compared to the AMB treatment for both tree species. However, growth parameters were significantly lower (P < 0.05) in the _fCO₂ treatment compared to that of the AMB treatment. Leaf N concentration was 1.1 to 2.1 times lower (P < 0.05) in all treatments when compared to current ambient conditions (AMB) in both tree species, but no significant changes in leaf C concentrations were observed. Results from our study suggested that _fCO₂ had the greatest negative impact on tree growth parameters, and leaf N concentrations were affected negatively in all treatments compared to current ambient conditions. It is expected that such changes in growth parameters and plant N content may impact the long-term cycling of nutrients in agroforestry systems.     

Influence of mulching and tree shelters on 4-year survival and growth of zeen oak (Quercus canariensis) seedlings

We assessed the effect of mulching and tree shelters on the establishment and early growth of zeen oak(Quercus canariensis Willd.) during the first 4 years after planting in Northwestern Tunisia. Five mulch types(Italian Stone Pine(Pinus pinea L.), Lentisk(Pistacia lentiscus L.),and a combination of Italian Stone Pine and Lentisk(organic mulches), gravel(inorganic mulch) and control), and three tree shelter types(non-vented and vented tree shelters, and control) were tested. An increase in the number of internodes occurred under the gravel mulch, while a reduction in survival was found for the lentisk mulch. Tree shelters had no effect on survival, but increased mean height growth and reduced mean diameter growth during the 4 years(excepting a non-significant effect for vented tree shelter at year four). Comparison of the annual shoots and growth units(GU) between sheltered and unsheltered plants according to year of formation revealed two growth phases. In first phase, shoots were totally or partially inside the shelters; mean length of annual shoots and GU were greater for sheltered plants. The second phase was characterized by shoots emerging from shelters; mean length of annual shoots and GU were similar for all plants, with or without tree shelters. Results suggest that the use of tree shelters, particularly vented shelters, could contribute to the improvement of the artificial regeneration of zeen oak.The use of mulching alone or in combination with tree shelters did not improve zeen oak performance in the field.     

Effect of elevated CO2 concentration on growth course of tree seedlings in Changbai Mountain

One-year-old seedlings ofPinus koraiensis, Pinus sylvestriformis, Phellodendron amurense were grown in open-top chambers (OTCs) with 700 and 500 ώmol/mol CO₂ concentrations, control chamber and on open site (ambient CO₂, about 350 ώmol/mol CO₂) respectively at the Open Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, and the growth course responses of three species to elevated CO₂ and temperature during one growing season was studied from May to Oct. 1999. The results showed that increase in CO₂ concentration enhanced the growth of seedlings and the effect of 700 (ώmol/mol CO₂ was more remarkable than 500 ώmol/mol CO₂ on seedling growth. Under the condition of doubly elevated CO₂ concentration, the biomass increased by 38% in average for coniferous seedlings and 60% for broad-leaved seedlings. With continuous treatment of high CO₂ concentration, the monthly-accumulated biomass of shade-tolerantPinus koraiensis seedlings was bigger in July than in August and September, while those ofPinus sylvestriformis andPhellodendron amurense seedlings showed an increase in July and August, or did not decrese until September. During the hot August, high CO₂ concentration enhanced the growth ofPinus koraiensis seedlings by increasing temperature, but it did not show dominance in other two species. Foundation Item: This paper was supported by Chinese Academy of Sciences and the Open Research Station of Changbai Mountain Forest Ecosystem.     

闪式提取樟树籽油工艺优化

为探索闪式提取法提取樟树籽油的最佳工艺,选取对提取工艺影响较大的液料比、电压、提取时间3个因素,并在单因素试验的基础上,进行Box-Benhnken中心组合设计,利用响应面法对提取工艺进行优化。结果表明：闪式提取樟树籽油的最佳工艺条件为液料比12∶1、电压170 V、提取时间120 s,在最佳工艺条件下出油率为67.97%。认为闪式提取法可作为一种快速有效的樟树籽油提取方法。     

Influence of canopy structure on the survival and growth of underplanted seedlings

This study explores the indirect relationship between forest structural measures and initial seedling survival and growth along a structural gradient between 64% to 92% canopy closure. The gradient was created by applying various levels of midstory removal to fifty 0.05 ha areas located within a mixed-hardwood riparian forest corridor. Twelve yellow-poplar (Liriodendron tulipifera L.) and cherrybark oak (Quercus pagoda Raf.) containerized seedling pairs were underplanted within each area. Canopy closure was estimated using hemispherical photography; height-to-canopy and basal area were recorded at each seedling pair. Survival, basal diameter, and height were monitored through two growing seasons. Species-specific mortality and height growth models were developed for one and two growing seasons following underplanting. The interaction of height-to-canopy and basal area along with canopy closure were found to be the most strongly related to mortality. Height to the forest canopy and initial seedling size explained the most variance in height increment. Although the height increment models possess limited predictive power (R² range from 0.22 to 0.36), both mortality and growth analyses emphasize the importance of quantifying vertical canopy structure, along with the more commonly considered horizontal measures of forest structure (basal area and stem density), when evaluating seedling development beneath a forest canopy.     

Influence of pasture botanical composition and fertilization treatments on tree growth

Silvopastoral systems, which combine tree and pasture production, are more complex ecosystems than exclusively agronomic systems. Good silvopasture management should seek to increase positive interactions (or synergies) and reduce negative interactions among system components (soil, trees, grass and cattle) to increase global system productivity. Tree growth and pasture production within such systems can be optimized through appropriate species selection and fertilization. The aim of the present study, carried out over the course of 3 years, was to compare how traditional fertilisation, sewage sludge dose, and potassium affect pasture-tree competition, botanic composition and tree growth in a silvopastoral system located on agricultural land during the early years of system development. The addition of potassium is recommended for improving tree growth in silvopastoral systems with slightly acidic soil, especially if the pasture has high legume content. White clover is a good choice of species for silvopastoral systems because it promotes tree growth. Our study revealed that pasture production improved when sewage sludge was used as a fertiliser, but annual production was still more strongly dependent on weather conditions.     

Effects of nitrogen on the growth and competition between seedlings of two temperate forest tree species

To understand how coexisting temperate tree species react to nitrogen (N) addition, seedlings of two coexisting species, Phellodendron amurense Rupr. and Fraxinus mandshurica Rupr. were transplanted to a controlled environment. Seedlings were then planted in two competition scenarios, control and mixed, and then subjected to four N addition treatments. The seedling growth parameters and competition effect were monitored and analyzed. The height and stem-base diameter showed a positive response to the N addition in all competition scenarios except for mixed P. amurense, which responded negatively. Chlorophyll content of the seedlings showed a positive relationship to N addition while the chlorophyll a/b showed a complex trend. The addition of N showed a positive relationship to the competition effect of diameter growth in both species and height growth in P. amurense. These results indicate that F. mandshurica may be more sensitive to N addition and could benefit more from N addition than P. amurense. With an increasing N input from the atmosphere, forests may be more suitable for F. mandshurica reducing the abundance of P. amurense.