Effect of early transplanting upon growth and development of spruce and pine seedlings in paperpot containers

Black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.) seedlings were transplanted into Japanese paperpots at five different stages of development between the occurrence of an erect hypocotyl and 14 days after initiation of primary needles. Transplanting difficulty increased between the first and last treatments, and transplanting generally became impracticable after the stage of primary-needle initiation. Transplanting had a relatively minor effect on the eventual size of 12-week-old pine and 16-week-old spruce seedlings, although the incidence of root deformities inside the container increased rapidly as transplanting was delayed beyond the erect-hypocotyl stage. These deformities persisted after seedlings were outplanted, but did not appear to have a negative effect on the subsequent growth of new roots into the planting medium. Despite the absence of major adverse effects, it is recommended that transplanting be avoided as a routine practice for supplementing stocking in trays of containerized seedlings because of possible biological risks, the difficulty of ensuring careful transplanting and high labor costs.     

A jack pine survival model for spring-lifting and planting delays in Ontario

The general problem of developing a model capable of exploring the survival response of seedlings to tradeoffs in the timing of spring lifting, planting and cold storage was investigated. After the construction of an overall model framework, one general and three specific functions to predict first-year survival for batches of 2 + 0 jack pine seelings were developed. The independent variables required by the functions include: cold storage duration (days), average air and soil temperature during planting (°C), cumulative degree days at time of planting (°C), ratio of terminal-to-top length at time of lifting, and cumulative degree days at time of lifting (°C). A brief example of the type of use to which such functions could be put, and an indication of the expected level of confidence that may be placed in such a prediction, is presented. The survival functions developed in this study were not designed for widespread use throughout the Province of Ontario. At most they should be limited to 2 + 0 jack pine planting stock originating from Swastika Nursery, and planted nearby.Approved for publication as Journal Article No. J-7315 of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State University.     

Frost hardening spruce container stock for overwintering in Ontario

Difficulties overwintering container stock in northern Ontario led to the development of the extended greenhouse culture hardening regime for spruce seedlings. Laboratories to measure shoot frost hardiness and evaluate terminal bud development were established to monitor nursery crops being hardened using this regime. Information on frost hardiness and bud development provided by these laboratories has been used by nursery managers to determine readiness of container seedlings for overwintering. Since 1982, over 200 stock lots have been monitored by these operational laboratories. This database can be used to determine the importance of nursery cultural factors and seed source on frost hardening. The database shows large differences between nurseries in approach to hardening seedlings which were reflected in levels of freezing damage, winter desiccation and overwintering success. Rates of frost hardening (i.e., the interval between terminal bud initiation and attainment of a --15°C level of shoot frost hardiness) of crops produced in north central Ontario failed to show significant seed source effects. The rate of frost hardening was faster in crops producing fewer needle primordia in terminal buds.     

Determining thresholds of low soil temperature for ecophysiological traits of black spruce and jack pine seedlings

Many studies have estimated approximately ranges of thresholds of low soil temperature in the growth and ecophysiological traits of trees, but difficultly determined the exact values. To resolve the problem, black spruce (Picea mariana) and jack pine (Pinus banksiana) seedlings were exposed to 5, 10, 15, 20, 25, 30 and 35°C soil temperature in greenhouses. After 90 days of the treatment, net photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), water use efficiency (WUE) and specific l...     

黑杨无性系日CO2固定总量的测定及与苗木生产潜势的相关性研究

通过对不同基因型黑杨无性系植株净光合速率日变化曲线与光合主体叶面积在时间和光强上进行累计积分来计算植株日CO2固定总量P。由于净光合速率日变化曲线不易准确测得，故以光响应曲线和光强的日变化来推测净光合速率日变化。对P值和生物量的相关性研究表明，二者的相关性很高。且认为可以用计算出的P值作为评估苗木生产潜势的指标之一，这为育种中生产力的早期选择提供了有力的证据。     

Effects of soil temperature on biomass production and allocation in seedlings of four boreal tree species

One-year old seedlings of trembling aspen (Populus tremuloides Michx.), black spruce (Picea mariana (Mill.) B.S.P.), white spruce (Picea glauca (Moench) Voss), and jack pine (Pinus banksiana Lamb.) were subject to seven soil temperatures (5, 10, 15, 20, 25, 30 and 35 °C) for 4 months. All aspen seedlings, about 40% of jack pine, 20% of white spruce and black spruce survived the 35 °C treatment. The seedlings were harvested at the end of the fourth month to determine biomass and biomass allocation. It was found that soil temperature, species and interactions between soil temperature and species significantly affected root biomass, foliage biomass, stem biomass and total mass of the seedling. The relationship between biomass and soil temperature was modeled using third-order polynomials. The model showed that the optimum soil temperature for total biomass was 22.4, 19.4, 16.0 and 13.7 °C, respectively, for jack pine, aspen, black spruce and white spruce. The optimum soil temperature was higher for leaf than for root in jack pine, aspen and black spruce, but the trend was the opposite for white spruce. Among the species, aspen was the most sensitive to soil temperature: the maximum total biomass for aspen was about 7 times of the minimum value while the corresponding values were only 2.2, 2.4 and 2.3 times, respectively, for black spruce, jack pine and white spruce. Soil temperature did not significantly affect the shoot/root (S/R) ratio, root mass ratio (RMR), leaf mass ratio (LMR), or stem mass ratio (SMR) (P>0.05) with the exception of black spruce which had much higher S/R ratios at low (5 °C) and high (30 °C) soil temperatures. There were significant differences between species in all the above ratios (P<0.05). Aspen and white spruce had the smallest S/R ratio but highest RMR while black spruce had the highest S/R but lowest RMR. Jack pine had the highest LMR but lowest SMR while aspen had the smallest LMR but highest SMR. Both LMR and SMR were significantly higher for black spruce than for white spruce.     

Applications of chlorophyll fluorescence for stock quality assessment with different types of fluorometers

New Forests - We demonstrate some stress detection and stock quality applications of fluorescence to conifer seedlings using two types of fluorometers: an integrating fluorometer (IF) for...     

Effects of commercial thinning,log position in the stem,and cutting width on the surface quality of cants produced by a chipper-canter

Fifteen stems of jack pine (Pinus banksiana Lamb.) of 3 commercial thinned plots (control, moderate, and intensive thinning) and 15 stems of black spruce (Picea mariana (Mill.) B.S.P), both coming from the Abitibi-Témiscamingue region – Canada, were cross-cut into three 2.4?m length sections: bottom, middle, and top logs. Logs were processed with a chipper-canter at three cutting widths (12.7, 19.1, and 25.4?mm), producing chips and a three-faced cant. The middle section of the cant was used to evaluate surface quality across the grain on each face. Roughness and waviness parameters and depth of torn grain were recorded. Knot characteristics were assessed in the three cant faces. Poorer surface quality was found in the lower part compared to the upper part of the cant for both species. At larger cutting widths, jack pine logs coming from a natural stand showed lower surface quality compared to logs from thinned stands. Black spruce waviness increased with the cutting width and stem height. These results were attributed to the increase of forces and vibration when cutting at larger cutting widths, which was worsened by the presence of bigger, more numerous knots at the control plot and in the top logs. Black spruce had deeper torn grain compared to jack pine. Their differences in knot characteristics resulted in a maximum torn grain depth favored by the presence of more knots rather than by bigger knot size. Other knot characteristics, such as the position of the knots in the cant face, the insertion angle of the branch and the distribution of the knots around the log, should be studied to better understand the relationship between torn grain formation and knottiness.     

Transversal tracheid dimension in thinned black spruce and Jack pine stands in the boreal forest

Abstract

Commercial thinning has recently been applied in the boreal forest of Quebec (Canada) to increase the volume growth of the residual trees. We aimed to discover if the growth response influences the transversal tracheid dimension of thinned black spruce (Picea mariana (Mill.) B.S.P.) and Jack pine (Pinus banksiana Lamb.) stands at 0.2 m stem height. All 20 studied stands have shown a significant growth response after the treatment (p<0.0001), especially trees with the lowest radial growth before thinning in comparison with the stand mean. Growing conditions met by suppressed trees before thinning might favour them in the competition for light, water and biomass production after the treatment. Trees with a positive growth response did not significantly modify their measured transversal tracheid dimension except for trees which increased twofold their ring-width after thinning. In this case, lumen area and radial cell diameter extended significantly. However individuals with a growth decrease after thinning registered significantly lower values in their ring width, earlywood and latewood cell numbers (p<0.0001) in both species.     

Planted conifer seedling growth under two soil thermal regimes in high-elevation forest openings in interior British Columbia

A field trial was conducted investigating the single season growth response of 1+0 313 PSB Engelmann spruce (Picea engelmannii Parry ex Engelm.) and lodgepole pine (Pinus contorta Dougl. ex Loud.) seedlings planted into two different soil thermal regimes at three high-elevation locations spanning 200 km in the Engelmann Spruce-Subalpine Fir (ESSF) biogeoclimatic zone in the Cariboo Mountains of central British Columbia. Temperature treatments represented the extremes of soil temperature commonly found in high-elevation clear-cuts. A warm soil treatment (clear day, mid-afternoon soil temperature in mid-summer of 18 to 25 °C at –10 cm) consisting of a bare mineral soil hummock (average dimensions of 100 cm × 100 cm × 40 cm) was contrasted with a cool soil treatment (clear day, mid-afternoon soil temperature in mid-summer of 10 to 13 °C at –10 cm) comprised of organic forest floor overlying mineral soil. By the end of the growing season, seedlings of both species planted into the warm treatment generally exhibited greater root, stem, foliage, and total seedling biomass than cool treatment seedlings. Measurements of root growth at 30, 60, and 90 days after planting showed that total root number and total root length were consistently greater for warm treatment seedlings than for cool treatment seedlings. Root growth was greater from the bottom rather than from the side of the root plug for all seedlings. These results suggest that the effect of low soil temperatures on outplanted styroblock conifer seedlings is pronounced and may be limiting growth performance in high-elevation plantations in British Columbia. We recommend silvicultural treatments that secure natural regeneration, ensure that warmer microsites are always planted, and utilize seedling stocktypes able to make rapid lateral root growth into warmer surface organic horizons.     

湖南省城市森林苗木产销现状及走势分析

湖南是全国城市森林苗木生产大省,2007年全省城市森林苗木生产面积2.67万hm2,年销售额34亿元,分别占全省花木生产总面积及年销售额的80.2%、75.6%。"浏阳河百里花木产业带"的建成,使省会长沙成为中南地区最大的城市森林苗木生产与集散中心。全省各地苗市有喜有忧,花灌木和大、中规格全冠苗畅销,小规格乔木和截干移栽大树积压严重。苗木品种结构调整和标准化生产势在必行。       

定海松林的演替趋势及更新改造设想

通过对定海松林及更新层的调查，发现多数松林在皆伐后演替为落叶阔叶林，少数为常绿落叶阔叶林和灌、草丛。更新树种共计34种，占优势的仅9种，且多为落叶阔叶树种。针对演替类型及更新树种存在单调贫乏的现状，结合海岛具体实际，提出封山育林、人工造林和树种选择的方向性建议，将为松村线虫病除治迹地的更新改造提供依据。     

世界林产品生产消费状况及对中国可持续林业发展的启示

根据联合国粮农组织公布的<世界森林资源评估报告>及我国<2000～2007中国林业发展报告>等文献公布的数据,就世界森林资源现状及主要林产品的变化情况进行了简要的介绍和分析;同时结合我国主要林产品生产情况,对我国森林资源消费的现状和发展进行简要分析,为我国经济建设和林业可持续发展提供参考.