首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Five exotic tree species (Acacia angustissima (Mil.) Kuntze, A. mangium Wild, Gliricidia sepium (Jacq.) Alp., Leucaena hybrid (L×L), and Leucaena leucocephala (Lam.) de Wit) were investigated to determine whether parameters of nursery seedling stock quality could be used to predict their field performance in a plantation irrigated with treated waste-water to produce fodder and wood. Plants were grown in the nursery in two contrasting rooting substrates (ordinary nursery soil and sand), predicted to have different effects on resource allocation. Three categories of morphological indicators were measured, i.e., plant dimensions (height, diameter, root length), plant weights (shoot, root and whole plant weights) and indices (sturdiness quotient ‘SQ’, shoot:root dry weight ratio ‘SRR’ and Dickson’s quality index ‘DQI’). In the nursery, all species performed better in the ordinary nursery soil for all growth parameters except root length. Thus ordinary nursery substrate appeared superior to sand in terms of plant quality. However, a follow up at plantation phase revealed that only some morphological attributes or ratios were suitable to predict field performance for the five tested species in irrigated plantation. In addition, the effect of the substrate observed at the nursery stage had disappeared 12 months after out planting due to the availability of water and nutrients provided by the treated waste water used for the irrigation. The results showed that root collar diameter and DQI appeared to be the most appropriate indicators to predict the outplanting performance of the five tested species in a short-rotation irrigated plantation in semi-arid Burkina Faso. The former measure is simpler and non-destructive.  相似文献   

2.
The relationships between field performance of Douglas-fir (Pseudotsuga menziesii) 2+0 seedlings and their initial diameter and root mass were evaluated on five sites in Oregon in the early 1980s to identify opportunities for improving seedling grading prior to planting. Survival and height 3–5 years after planting were positively related to seedling size at the time of planting. On all sites, survival nearly doubled from the smallest to largest diameter classes. Root mass had a similar relationship to survival on sites with environmental stress. Increasing root size class increased survival more for the small diameter classes than for the larger diameter clases. On the other hand, increasing root size class increased total height more for the large diameter class than the smaller ones. Although height was not as strongly affected as survival on several sites, height differences among initial seedling diameter classes were still significant and increasing after five years. Root class effects on height were less important than diameter class effects.  相似文献   

3.
红豆树苗木质量评价指标的研究   总被引:8,自引:2,他引:8  
郑天汉 《福建林业科技》2007,34(4):71-73,90
红豆树1年生苗木质量评价标准为:Ⅰ级苗的临界值:总鲜重≥56.9 g,地径≥34.2 cm,苗高≥46.7 cm;Ⅱ级苗的临界值:56.9 g>总鲜重≥17.1 g,0.98 cm>地径≥0.67 cm,43.0 cm>苗高≥23.2 cm;Ⅲ级苗的临界值:17.1 g>总鲜重≥11.9 g,0.67 cm>地径≥0.56 cm,23.2 cm>苗高≥16.9 cm;Ⅳ级苗的临界值:总鲜重<11.9 g,地径<0.56 cm,苗高<16.9 cm。  相似文献   

4.
Rigney  Michael P.  Kranzler  Glenn A. 《New Forests》1997,13(1-3):51-62
A PC-based line-scan machine vision system providing rapid measurement of bare-root seedling morphological features has been developed. Designed for quality control and morphological data acquisition by nursery personnel, the machine provides a user-friendly, menu-driven graphical interface. Individual seedlings are manually placed on a conveyor belt and inspected in less than 0.25 seconds.The machine automatically locates the root collar and measures stem diameter, shoot height, sturdiness ratio, root mass length, projected shoot and root area, shoot-root area ratio, and percent fine roots. Sample statistics are computed for each measured feature. Measurements for each seedling may be stored for later analysis. Feature measurements may be compared with multi-class quality criteria to determine sample quality or to perform multi-class sorting. Statistical summary and classification reports may be printed to facilitate the communication of quality concerns with grading personnel.Tests were conducted at a USDA Forest Service nursery to evaluate measurement precision. Four quality control personnel measured root collar diameter, shoot height, and root mass length on 100 2--0 Douglas fir and 100 2--0 Ponderosa pine seedlings. The same seedlings were inspected four times by the machine. Root collar diameter measurement standard deviation of the machine was 25% that of manual measurements. Machine and manual measurements had comparable precision for shoot height and root mass length.  相似文献   

5.
Mechanical shock during transportation: effects on seedling performance   总被引:1,自引:0,他引:1  
Stjernberg  Ernst I. 《New Forests》1997,13(1-3):401-420
A study was carried out to monitor shocks to seedling planting stock during transport from nursery to the planting site in normal commercial reforestation operations. Size and exact time of mechanical shocks were measured by a recorder placed inside seedling boxes. Seedling shipments by refrigerated semi-trailer, 5-ton truck, pickup truck, small trailer and all-terrain vehicles were monitored in Alberta and British Columbia. Number of shocks, peak acceleration and average drop height were tabulated for travel on both paved and gravel roads.Twenty-two trials involving seven species were established at nurseries and field locations covering several ecological zones in both provinces. Frozen-stored, cool-stored, and freshly lifted seedlings were used in the trials. Seedlings were given two mechanical stress treatments by dropping them 30 times from 0.5-m and 30 times from 1.0-m, respectively. Control seedlings were not dropped. Treatments were applied to nursery-trial seedlings not exposed to normal handling and transport, and to field-trial seedlings after transport to the planting site. Six root growth potential tests were made with treated and control seedlings in conjunction with the nursery trials.Seedling survival and volume growth were recorded for two growing seasons and the results statistically analysed.  相似文献   

6.
Abstract

Seedling morphological quality standards are lacking for bottomland hardwood restoration plantings in the Lower Mississippi River Alluvial Valley, USA, which may contribute toward variable restoration success. We measured initial seedling morphology (shoot height, root collar diameter, number of first order lateral roots, fresh mass, and root volume), second year field heights and diameters, survival, browse, and top dieback of five species – cherrybark oak (Quercus pagoda Raf.), green ash (Fraxinus pennsylvanica Marsh.), Nuttall oak (Q. nuttallii Palmer), sweet pecan (Carya illinoensis (Wangenh.) K. Koch), and water oak (Q. nigra L.). Seedlings were obtained from three regional nurseries (Arkansas, Louisiana, and Mississippi), planted on three sites (Arkansas, Louisiana, and Mississippi), and treated with or without chemical weed control. Site×nursery interaction and weed control (without interactions) usually affected survival, whereas site×weed control interaction and nursery (without interactions) influenced second year heights and diameters. Weed control generally increased survival rates, as well as second year height and diameter. Effects of initial morphological characteristics on field survival and height and diameter growth were generally dependent on the other morphological parameters. Target morphological characteristics were identified as 99, 84, and 82 in height/diameter ratios (equal units) for cherrybark oak, green ash, and Nuttall oak, respectively; mean initial height of 40–43 cm in sweet pecan; and mean initial fresh mass/root volume of 2.7 g ml?1 in water oak. Seedlings with means above these values may be more susceptible to dieback or mortality after outplanting, likely associated with excessive shoot relative to root biomass.  相似文献   

7.
失水程度对苗木质量的影响   总被引:1,自引:0,他引:1  
失水程度对造林成活率和初期生长量有显著影响,失水超过一定程度苗木即失去生机  相似文献   

8.
This study examined the relationship between root collar diameter, plant moisture stress and budbreak in three morphological grades of bareroot 1+0 slash pine (Pinus elliottii Engelm.) nursery seedlings and assessed the role of these parameters in predicting field performance potential under operational conditions. Two months after outplanting seedlings with small (3.2 mm) diameters exhibited greater signs of moisture stress than those with the largest (4.7 mm) diameters, as determined by lower xylem pressure potential values. Intermediate and large-sized seedlings (diameter >3.2 mm) showed earlier budbreak than smaller seedlings with more rapid shoot elongation after planting and had significantly greater survival rates for two years after planting on both a moist flatwoods and a dry sandhill planting site. However, after two years on the more favorable moist site, height and diameter measurements of seedlings with significantly smaller diameters initially did not differ from those of intermediate sized seedlings (diameter >3.2 and <4.7 mm). Large seedlings had greater second-year leader and diameter increments and attained greater total height and diameter after two years on both sites. Decreasing the proportion of smaller seedlings included in the field performance analyses increased overall mean plantation survival while increasing the proportion of large seedlings increased mean two-year total height and diameter as well as annual growth increments.  相似文献   

9.
为提高20世纪80年代后期营建的1.5代杉木种子园遗传品质和种子产量,以子代材积增益、当代种子产量均高为标准,选择用于成年种子园提质改造的优良无性系。经综合评价,选择出了靖大30、靖大35、广洋45等可用于杉木成年种子园提质改造的优良无性系20个。采用随机区组设计的方法开展优良无性系容器育苗试验。结果表明:以高度17 cm、直径19 cm规格的容器,按体积比配置70%泥炭土、25%黄心土、5%珍珠岩的混合基质培育容器砧木苗,在砧木保留3轮底枝的部位进行嫁接,切接或舌接法培育2年生容器嫁接苗成活率达90%以上、苗高达93 cm以上。  相似文献   

10.
[目的] 通过对不同容器规格和基质配方条件下1,2年生红锥幼苗生长及造林效果对比分析,为2种年龄红锥苗木培育筛选出适宜的容器规格和基质配方,亦为其造林适宜苗龄的选择提供科学依据。[方法] 采用2种容器规格和11种基质配方分别培育1,2年生红锥苗,测定红锥苗期的生长动态,并开展造林试验,调查其早期生长表现。运用方差分析、多重比较等方法,探明不同容器规格和基质配方条件下红锥幼苗生长差异,应用相关分析揭示红锥苗期生长与造林效果的相关性。[结果] 容器规格和基质配方显著影响1,2年生红锥苗的苗高、地径、根生物量和总生物量(P<0.05),且两者交互作用对1,2年生幼苗的苗高、地径、根生物量以及2年生幼苗的总生物量具有显著影响。1年生红锥苗造林当年,各基质配方的造林保存率差异不显著(P>0.05),而幼树高差异显著;造林第2年,各基质配方的造林保存率和幼树高差异不显著,而地径差异显著。2年生红锥苗造林当年,各容器规格的造林保存率、幼树高和地径均差异显著,各基质配方的造林保存率差异不显著,而幼树高和地径差异显著。容器规格和基质配方的交互作用对2年生红锥苗造林当年幼树高具有显著影响。1年生红锥苗造林,当年幼树高、第2年幼树高和地径与造林前苗高、地径、根生物量和总生物量呈显著正相关,且当年和第2年幼树高与造林前幼苗根冠比呈显著负相关。2年生红锥苗造林,容器规格1(8 cm×12 cm,直径×高)当年幼树高、地径与造林前苗高和总生物量呈显著正相关,容器规格2(12 cm×15 cm,直径×高)当年幼树高与造林前苗高、地径、根生物量和总生物量呈显著正相关,而当年幼树地径与造林前总生物量呈显著正相关,表明红锥苗木质量显著影响其前两年造林效果。[结论] 容器规格与基质配方对1,2年生红锥苗木生长存在交互作用,因此红锥苗期适宜基质配方选择应依据苗龄和容器规格而定。培育1年生红锥苗,建议采用容器规格1和基质配方10(50%沤制树皮+25%黄心土+25%锥林表土);培育2年生红锥苗则采用容器规格2和基质配方7(50%沤制树皮+50%锥林表土)。在杂灌控制及时的良好立地,采用容器规格1培育1年生红锥苗,其造林效果优于容器规格2培育的2年生红锥苗。  相似文献   

11.
Each link in initial process of artificial regeneration ofPinus koraiensis in clear cutting site was researched. The seedling recovery processes after transplantation, the affecting seedlings survival factors in different time, and the characters of seedling growth were analyzed. Results of this study suggest that the root recovery of Korean pine seedlings after transplanting is the key link in the artificial regeneration management. The synthetically management was proposed on basis of seedling root recovery process. The project was surpported by Natural Science Fund of Heilongjiang Province  相似文献   

12.
Correlations between root growth capacity (RGC), at the time of planting, and field performance were studied for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings. Before planting a gradient in seedling viability was generated through exposure to low root temperatures and different winter storage regimes. The hypothesis that high RGC values would improve field performance was to some extent verified for pine seedlings while no correlations could be registered for spruce. Reasons for these results are discussed.  相似文献   

13.
South  David B.  Hallgren  Stephen W. 《New Forests》1997,13(1-3):357-365
Relationships between root growth potential (RGP) and plantation survival were evaluated for 12 families of shortleaf pine (Pinus echinata Mill.) from Oklahoma and Arkansas in 2 consecutive years. Bare-root, 1+0 seedlings were either planted one day after lifting (nonstored) or were stored at 1° to 3°C for 4 weeks. Correlations were obtained using the traditional research method where seedlings are planted in the field prior to obtaining results from the RGP test. In addition, operational correlations were derived by planting seedlings after obtaining RGP test data.For nonstored seedlings, research correlations were generally higher (r values were larger in 18 of 24 cases) than operational correlations. The predictive ability of operational correlations may not be high enough with 28-day pot tests to warrant batch culling of freshly lifted shortleaf pine. However, results were mixed for stored seedlings. In one year, operational correlations were generally higher than research correlations.  相似文献   

14.
Mohammed  Gina H. 《New Forests》1997,13(1-3):491-514
Stock quality testing (SQT) is a vital component of forest regeneration programs world-wide. SQT consists of stock quality control (SQC) during production at the nursery and planting stock quality assessment (PSQA) prior to planting. Current tests being used for SQC and PSQA are reviewed, indicating whether they are used on an operational or research scale. Prediction of growth by PSQA is still not far advanced, and the operational application of physiological methods in particular in SQT is still limited, although progress varies according to country or region. Challenges in implementation of operational SQT are reviewed, and a 'total quality management' approach to addressing the challenges is proposed.  相似文献   

15.
With over 1.5 billion forest tree seedlings produced annually in the USA, seedling quality assessment is critical to ensure reforestation success. While height and root-collar diameter are the most common traits evaluated during seedling quality assessment, above-ground morphology is not always an accurate predictor of performance after outplanting. Root system morphology and physiological status may provide a more accurate indication of seedling potential. However, relatively few studies have attempted to quantitatively assess root system quality in relation to outplanting success. Large root volume, high root fibrosity, and an increased number of first-order lateral roots have shown some correlation to improved field performance. Physiological seedling quality assessment is commonly practiced through evaluation of root growth potential. Other tests, such as root electrolyte leakage, have also shown some potential as measures of seedling physiological quality. This review identifies current methods of assessing seedling root system quality and discusses potential shortcomings of these methods. An increased understanding of the suitability of current tests, coupled with the development of new tests and multiple parameter relationships, may foster the development of species and site-specific targets for seedling root system quality assessment. The production of seedlings with root systems that meet high morphological and physiological standards better enables seedlings to rapidly establish and thrive upon outplanting.  相似文献   

16.
Folk  Raymund S.  Crossnickle  Steven C. 《New Forests》1997,13(1-3):121-138
An operational assessment of stock quality, prior to field planting, usually includes measures of morphology and a test for root growth capacity (RGC) conducted under optimum conditions. When measured under optimum conditions and interpreted with regard to seedling phenology, performance attributes, such as RGC, provide valuable information about the functional integrity of stock at the time of measurement. However, reforestation sites are rarely associated with optimum growing conditions, and performance attributes measured under optimum conditions provide limited information about field performance potential. Due to these limitations, testing programs at the Forest Biotechnology Centre (BCRI) have used limiting environmental conditions to represent the planting site. This concept is based on the philosophy that tests under limiting environmental conditions will define seedling tolerance and/or resistance to conditions that prevail on the planting site, and hence, better forecast field performance potential. Evidence supporting this concept is presented in three case studies and other cited studies, where performance attributes were measured under a range of limiting environmental test conditions. A performance attribute response model is then presented to define the relationship between testing conditions and field performance potential forecasting. Applicability of this testing approach to operational reforestation programs is discussed.  相似文献   

17.
After cold storage, conifer seedlings in British Columbia are tested for field growth potential before planting. We compared three tests of performance potential using container-grown seedlings of Douglas-fir, interior spruce, lodgepole pine, and western larch (14 seedlots total). On several autumn dates, seedlings were lifted and stored at −2°C. The following spring we tested stored seedlings for root growth potential (RGP), chlorophyll fluorescence (CF), and stomatal conductance (Gs), and then planted seedlings in nursery beds. We assessed survival and shoot dry weight (SDW) after one growing season. Performance test results were significantly correlated with each other (r ≥ 0.47) but showed different relationships with field performance, which varied with lift date. The best performance predictor was the sum of CF and RGP (R 2 = 0.79 for 78 seedlot by lift-date combinations), which minimized the risk of planting poor seedlings and not planting good seedlings. A sum of 83 for CF (Fv/Fm %) and RGP (new roots >1 cm) provided a threshold above which survival and growth were good. For evergreen conifers, Gs was a good performance predictor, but required extra time to measure leaf area. We recommend a combination of CF and RGP to assess vigor of shoot and root systems before planting. Wolfgang D. Binder––Scientist Emeritus.  相似文献   

18.
烤烟叶片田间生长过程中叶片干鲜比值的变化   总被引:1,自引:0,他引:1  
田间状况下对烤烟下、中、上三个部位叶片生长发育过程中叶片干鲜比值的变化进行了研究。结果表明:在烤烟田间叶片生长发育过程中,随着烟叶部位的上升,叶片干鲜比值表现为随之增加的变化规律,不同烟叶部位之间叶片干鲜比值的差异显著,而不同叶龄之间叶片干鲜比值的差异不显著。随着叶龄的增大,三个烟叶部位叶片干鲜比值的变化不尽一致,下部叶表现出随之缓慢降低的变化规律,中部叶表现为“锯齿”型的变化,上部叶表现为随之逐渐增加的变化规律。相关分析表明,叶龄与叶片干鲜比值之间呈不显著正相关。  相似文献   

19.
Bond quality and joint performance between laminated veneer lumber (LVL) and metal plates were investigated. Commercially fabricated LVL made of Douglas fir veneer and bonded with phenol-formaldehyde resin as well as three types of epoxy adhesives were used. Various surface preparations and treatments were applied to ordinary steel, stainless steel, and aluminum plates to remove the weak boundary layer that is incompatible with the resin and form a stable adherend layer that is chemically and mechanically compatible with the resin. Small specimens were tested in shear to search the most suitable metal surface for bonding with LVL. Generally, shear strength obtained for the specimens bonded with aluminum plates was lower than those bonded with ordinary steel plates. Among them chemically treated (ChT) and roughened (R) surfaces have demonstrated superior performance. To investigate strength performance and bond quality, LVL beams jointed with metal plates were tested while bending. The best results were obtained for specimens bonded with zinccoated metal plates, though good results were obtained also for ChT and R plates. However, the fracture proved to be fragile when no drift pins were used, even for high-performance surface treatments. The usage of drift pins was necessary to add toughness and avoid the brittle status of the fracture.  相似文献   

20.
《Southern Forests》2013,75(4):217-227
The aim of site quality assessment of Pinus radiata plantations is to determine the quality and productivity of the growing stock at different sites. It provides a useful indication of the site productivity to assist in the allocation of optimum thinning and fertiliser regimes and the scheduling of silvicultural operations. The predominant stand height (PDH) at a specific reference age, also known as site index (SI), is often used for site quality assessment of Pinus radiata plantations in Australia, as it is closely correlated with site productivity. However, measuring PDH in the field can be a time- and resource-consuming task. This paper proposes the use of light detection and ranging (LiDAR) data to estimate PDH for assessing the site quality of Pinus radiata. LiDAR provides highly accurate digital elevation and surface data that can be used to build a canopy height model (CHM). In this study, the state-of-the-art image segmentation technique, marker-controlled watershed segmentation, was employed for identifying locations of individual trees and estimating their heights from a CHM. Using an empirically derived SI equation, PDHs with reference age 11 years (SI11) were estimated from the tallest trees identified in each forest stand, and were then used to determine the site quality class for each stand. The comparison of LiDAR-derived tree heights with field measurements produced an RMSE value of 0.42 m. The maximum horizontal distance between the field-measured locations of individual trees and the LiDAR-detected locations of their treetops was 1.87 m. Site quality classification was conducted in terms of 0.05 ha gridded plots, which revealed more detailed spatial variations of site quality across the study area than classification based on management plots. The study demonstrated that LiDAR provides an effective and accurate method for site quality classification of Pinus radiata.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号