Impact of seedling type on early growth of poplar plantations on forest and agricultural land

Today, most poplar plantations in the temperate region are established on abandoned marginal agricultural land, but there is great potential for planting poplars on forest land as the available area is large and does not compete with food production. The objective of this study was to examine how different planting types (un-rooted cuttings, bare-rooted and containerized plants) affect the establishment and early growth of poplar plants on forest and agricultural sites. Our results suggest that on the agricultural site, survival and growth during the first two years are not influenced by plant type. However, at the forest sites, survival of rooted plants was superior compared to un-rooted cuttings. The height and biomass (stem and root) increment of bare-rooted plants was low; greater height and biomass growth was found for containerized plants. Container sizes had no effect on height growth, but leaf and stem biomasses were higher if the largest containers were used. When using the largest containers, concentrations of macronutrients (N, P) were increased compared to bare-rooted plants. Thus, these results suggest that practices for establishing poplar plantations of agricultural land include planting of un-rooted cutting, but on forest land, a plant grown in a container of 470?ml should be used. Together, this can reduce the cost of establishment, increase the available area for poplar plantations and have an impact on poplar plantation economics in Sweden.     

裸根阔叶大树移植技术相关因素研究

对裸根阔叶大树移植时根在空气中的暴露时间、移植季节、种植方法及树干保湿度等进行了初步研究,提出了移植裸根阔叶大树的一整套完整的技术体系模式.     

Physiological and growth responses of three sizes of containerized Picea mariana seedlings outplanted with and without vegetation control

Three different stock sizes of containerized black spruce (Picea mariana [Mill.] B.S.P.) seedlings were planted in an abandoned agricultural field. The small planting stock was of a conventional type produced in 110 cm³ containers. The experimental medium and large stock types were produced in 340 and 700 cm³ containers, respectively. Gas exchange, xylem water potential and dry masses were measured six times during each of the first two growing seasons in field plots with and without vegetation control. During the first growing season, the effect of planting shock masked most physiological and growth differences among seedling types. During the second growing season, in plots with vegetation control, small and medium seedlings had similar values of physiological variables and of growth as measured by relative growth rates (RGR), but the large seedlings showed lower values of both net photosynthesis and of RGR, a difference attributed to low initial quality of the root system in the larger seedlings. In plots without vegetation control, the trend was identical, but differences were not significant; the greater height of the larger seedlings, and the resulting greater access to light, compensated for their lower initial quality. The similarity in response between the medium and the small seedlings shows that a fourfold increase in shoot size (1.68–6.82 g) in the initial size and a doubling of the shoot : root ratio (2.17–4.54) of the planting stock did not result in increased planting shock or reduced growth in these containerized conifer stock types. The results also show the importance of the interaction between stock height and the vertical light profile created by the competing vegetation in the final assessment of stock performance.     

梯田地埂灌木树种栽培技术研究

对西吉县梯田地埂灌木树种(以杞柳和柠条为主)的栽培技术进行了研究。结果表明：(1)造林整地时，梯形槽和鱼鳞坑整地均可，整地深度以40cm左右为宜，整地时间以雨季预整地最佳；(2)造林方法要根据具体树种而定。柠条最好选择植苗造林，春秋皆宜，杞柳适宜秋季造林，总体上秋造的苗木成活率和存活率明显好于春造。另外，在柠条播种造林时，坡向最好在阴坡；(3)杞柳造林时的种植深度以种条覆土2cm最佳，适宜的几种种植深度模式为：阳坡种条覆土2cm、阴坡种条齐地面、阴坡种条覆土2cm；(4)造林整地、种植深度对苗木生长量的影响较大，造林方法、造林坡向、种植深度对造林成活率和保存率的影响相对显著。     

不同造林方法对马尾松林分生长和分化的影响

对容器苗工程造林、裸根苗工程造林和裸根苗一般造林的马尾松林分进行跟踪分析认为，在立地条件较好的情况下（Ⅰ、Ⅱ类地）选择马尾松容器苗工程造林，对林分树高、胸径的生长较为有利，分化程度小，能达到速生丰产的要求；在立地条件较差的林地上（Ⅲ类地以下）选择棵根茵工程造林较为经济；裸根苗一般造林的马尾松林分生长缓慢，林分分化程度大，不符合速生丰产的要求。     

The effect of root and shoot pruning on early growth of hybrid poplars

Planting stock type and quality can have an important impact on early growth rates of plantations. The goal of this study was to evaluate early growth and root/shoot development of different planting materials in typical heavy clay soils of northwestern Quebec. Using one-year-old bareroot hybrid poplar dormant stock, four planting materials were compared: (1) regular bareroot stock, (2) rootstock (stem pruned before planting), (3) whips (roots pruned before planting), and (4) cuttings (30 cm stem sections taken from the basal portion of bareroot trees, i.e. roots and shoot pruned). Rooted stock types (bareroot and rootstock) produced, on average, 1.2 times larger trees than unrooted stock types (cuttings and whips). However, shoot-pruned stock types (rootstocks and cuttings) reached similar heights and basal diameters as unpruned stock types (bareroots and whips), during the first growing season. Shoot pruning reduced leaf carbon isotopic ratios, suggesting that unpruned stock types were water-stressed during the first growing season. The stress was most likely caused by early leaf development while root growth occurred later in the summer. We conclude that shoot pruning bareroot stock is a useful management option to reduce planting stress without compromising early growth rates of hybrid poplars.     

Tubed Seedling Research and Development in Britain

Based initially on Canadian practice, research on the productionand use of tubed seedlings in Britain has been in progress for3 years (1968–70), and was begun because of their potentialadvantages as planting stock. Polythene greenhouses are usedto produce pine and spruce seedlings grown in small plastictubes filled with fertilized peat-sand compost, and plantingis possible 8 weeks after sowing. On ploughed peat-land, step-plantedseedlings are capable of high survival and vigorous early growth,with an effective planting season from mid April to late August.Animal browsing is the main adverse factor encountered, buthas been less serious than expected. Very high planting ratesare possible with a special tool. Seedling use could lead tolarge savings in peatland afforestation costs, and large-scaletrials are planned. In contrast, seedling performance on ploughedmineral soil has been unsatisfactory due to severe frost liftingand poor height growth. Results in reafforestation trials havenot been very promising.     

Absolute and relative growth of Douglas-fir seedlings of different sizes

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings of a single seed source were grown in a bare-root nursery for two years to produce five different stock types by varying spacing and transplanting treatments. They were then planted in the forest together with one-year-old container seedlings of the same seed source, which constituted a sixth treatment. Stem volume mean relative growth rate (R(v)) was low immediately after planting for all stock types except the container seedlings, and increased over the following 7.6 years. An 8-week greenhouse test of the six stock types showed that dry weight mean relative growth rate (R(w)) generally decreased with seedling dry weight, but this effect was less obvious after planting, because only the three smaller stock types showed a decrease in R(w) with size. In another experiment, bare-root Douglas-fir seedlings were grown at five different spacings in a nursery for two years, and seedlings from each spacing treatment were sorted into large or small by height. The resulting 10 treatments were planted in the forest and stem volumes determined over 6.7 years. The linear effect of nursery spacing on stem volume was no longer evident 3.6 years after planting, but large seedlings had greater stem volume than the small seedlings throughout the 6.7 years of the study. There was no indication that R(v) declined with time, but small seedlings had higher R(v) than large seedlings. Relative growth rates of two-year-old Douglas-fir were depressed for a year or two after planting, but then remained relatively constant, or increased during the ensuing 5 years. Relative growth rates of smaller seedlings were greater than those of larger seedlings so that relative biomass differences decreased with time, and the time advantage (the time necessary for small seedlings to reach the present biomass of large stock) of larger stock decreased. Absolute size differences increased with time.     

Northern red oak planting stock: 6-year results

A northern red oak plantation was established in 1988 in a recently clearcut mixed oak stand to evaluate outplanting performance relative to type of planting stock (1--0, 2--0, 1--1, 2--1, 2-year-old containerized, and direct-seeded) and other cultural factors (undercutting in the nursery, raising stock in an extended growing season in Alabama vs a local Pennsylvania nursery, top-clipping at planting time, and tree shelters). Six years after outplanting, seedlings grown from 2-year-old containerized stock were tallest (averaging 3.3 m) and had excellent survival. Among other treatments, 2--0 bareroot stock, especially if undercut in the nursery and top-clipped at planting, performed best and averaged 3.0 m height and 100% survival. Remaining treatments, especially 1--0, were smaller and had reduced survival. Seedlings from direct-seeding were as tall as most 1--0 treatments. Undercutting, top-clipping, nursery transplanting, raising stock in different nurseries, and tree shelters minimally affected the height or survival of seedlings. Seedlings above average in height 3 years after outplanting when fencing was removed and herbiciding ceased, were most likely to survive after 6 years.     

油茶容器苗与裸根苗造林效果分析

针对新造油茶林幼苗成活率不高的问题,进行了油茶容器苗和裸根苗的对比造林试验,结果表明:容器苗造林比裸根苗造林在成活率、抽梢率、树高、冠幅表现出显著差异.容器苗比裸根苗表现出较强的抗旱性、适生性和稳定性.     

Effect of stock type characteristics and time of planting on field performance of aspen (Populus tremuloides Michx.) seedlings on boreal reclamation sites

Aspen (Populus tremuloides Michx) has great potential as a reclamation species for mining sites in the boreal forest, but planting stock has shown poor field performance after outplanting. In this study we tested how different aspen seedling characteristics and planting times affect field outplanting performance on reclamation sites. We produced three different types of aspen planting stock, which varied significantly in seedling size, root-to-shoot ratio (RSR), and total non-structural carbohydrate (TNC) reserves in roots, by artificially manipulating shoot growth during seedling production. All three stock types were then field-planted either in late summer, late fall, or early spring after frozen storage. Seedlings were outplanted onto two reclaimed open-pit mining areas in the boreal forest region of central and east-central Alberta, Canada, which varied significantly in latitude, reclamation history, and soil conditions. Overall, height growth was better in aspen stock types with high RSR and TNC reserves. Differences in field performance among aspen stock types appeared to be more strongly expressed when seedlings were exposed to more stressful environmental site conditions, such as low soil nutrients and moisture. Generally, aspen seedlings planted with leaves in the summer showed the poorest performance, and summer- or fall-planted seedlings with no shoot growth manipulation had much greater stem dieback after the first winter. This indicates that the dormancy and hardening of the stem, as a result of premature bud set treatments, could improve the outplanting performance of aspen seedlings, particularly those planted during summer and fall.     

Fine root electrolyte leakage and moisture content: indices of Sitka spruce and Douglas-fir seedling performance after desiccation

In spring 1992, 2-year-old bare-rooted seedlings of Sitka spruce (Picea sitchensis (Bong.) Carr.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were exposed for 0, 0.5, 1.0, 1.5, or 3 h in a controlled environment room at 20°C. Plants were desiccated in batches during February and March; 100 seedlings of each species were planted in 5 20-plant plots at each of 6 planting sites using the normal planting times and methods of each area. The effect of exposure was assessed within 24 h of desiccation on a subsample of plants by measuring fine root moisture content and electrolyte leakage and, in a limited number of cases, needle water potential. These measures were related to survival and growth after the first and second growing seasons.There were significant interactions between the effect of desiccation and site. The measurements following desiccation were significantly related to survival and growth on some but not all sites; in general, the effect of condition was more pronounced on sites with low spring rainfall than on sites with greater than 100 mm rainfall per month during the spring of planting. Root electrolyte leakage was significantly related to performance in slightly more cases than needle water potential or root moisture content.     

Nitrogen mobilization, nitrogen uptake and growth of cuttings obtained from poplar stock plants grown in different N regimes and sprayed with urea in autumn

Nitrogen mobilization, nitrogen uptake and growth of cuttings obtained from poplar stock plants fertigated with different nitrogen (N) treatments and sprayed with urea in autumn were studied. Stock plants propagated from poplar cuttings were trained to a single shoot and fertigated with 0, 5, 10, 15 or 20 mmol l(-1) N during the first growing season. In October, a subset of stock plants from each N fertigation treatment was sprayed twice with either 3% urea or water, and overwintered outside. In March, total tree biomass and total N concentration and content of stems were estimated for stock plants in each treatment, and cuttings were taken from the middle of each stock plant and stored in plastic bags at 2 degrees C. In mid-April, cuttings were planted in 7.5-l pots containing N-free medium and grown outdoors with a weekly fertigation with nutrient solution containing 0 or 10 mmol l(-1) 15NH4 15NO3. In mid-July, cuttings were harvested, and new shoot (new stems and leaves), shank (old cutting stem) and roots were analyzed for new biomass growth and total N and 15N content. Growth of stock plants was positively related to N supply in the previous growing season. Foliar urea application in autumn had no effect on subsequent stock plant growth even though urea sprays increased both N concentration and content in stem tissues. Biomass growth of cuttings obtained from stock plants was closely related to their N content when the cuttings were grown in an N-free medium regardless of previous treatments applied to the stock plants. When N was supplied in the growth medium, the strength of the relationship between regrowth and N content of cuttings was significantly reduced. Cuttings from stock plants treated with foliar urea and grown in a N-free medium remobilized between 75 and 82% of their total N for new growth, whereas cuttings from plants receiving no urea spray remobilized only between 60 and 69% of their total N for new growth. Current N fertilization of the cuttings reduced the percentage of N remobilized. We conclude that new growth of poplar cuttings in spring was more dependent on currently applied N than on reserve N, and urea N applied as a spray in autumn was more easily remobilized than N taken up by roots during the previous season.     

Interactions among forestry regeneration treatments,plant vigour and browsing damage by deer.

In a large field experiment we studied the influence of regenerationmethods on the extent to which roe deer (Capreoluscapreolus L.) browse on spruce (Picea abies L.Karst) seedlings. Our objective was to evaluate if treatments that are good atstimulating regeneration may increase browsing damage by deer. Data werecollected between 1993 and 1995, and in the winters of 1993–94 and1994–95 the frequency of browsed seedlings was 13.2% and 13.4%,respectively. The frequency of browsing damage varied considerably betweensitesand clearcuts. Browsing damage was more frequent when the regeneration methodsincluded insecticide treatments. Among insecticide-free treatments, browsingwasheavier on scarified plots than on herbicide-treated or control plots (in whichseedlings were planted on untreated ground and given no post-plantingtreatment). Containerised seedlings were browsed more than bare-rooted ones.Neither the age of clearcut when planting, nor removal of slash, had any effecton browsing. It was demonstrated that regeneration methods that increased plantvigour (as assessed by leader growth and needle colour index) led to morebrowsing damage. Thus, our results support the plant vigour hypothesis, whichstates that many herbivores prefer to feed on vigorous plants because they aremore nutritious. However, the difference in browsing damage betweencontainerised and bare-rooted seedlings could not be explained solely by theplant vigour hypothesis.     

Frost damage to planted Norway spruce seedlings — influence of site preparation and seedling type

Damage to Norway spruce (Picea abies (L.) Karst.) seedlings by summer frost was monitored on 10 clear-cuttings of various ages to which slash removal and four types of site preparation had been applied. The clear-cuttings were established on two sites (5 on each) in southern Sweden from 1989 through 1993 and planted each year from the year of cutting until 1993. In total, 7680 seedlings were analysed for frost injuries during the first three years following planting. The site preparation methods evaluated were: application of herbicide to ground vegetation; mowing of ground vegetation; scarification (mounding); and control. Two seedling types, bare-rooted and containerised seedlings, were evaluated.Periods of frost susceptibility were calculated using data on bud and shoot development during 1997 together with weather data for each of the studied years and sites. The date of flushing was well correlated to the air temperature sum (+5°C threshold value) in spring. Frost damage varied considerably between sites and study years. The lowest measured minimum air temperature and the frost-day sum during the frost-susceptible period were correlated to the frequency of frost damage. Soil scarification reduced frost damage in the first growing season. Bare-rooted seedlings had a considerably lower frequency of frost injury compared with containerised ones, possibly because flushing of the former was delayed. There was no statistically significant effect of herbicide application, mowing or slash removal on the frequency of frost damage. Seedling growth was significantly reduced by frost injury, especially in cases where injuries were sustained during several years. Survival was only slightly affected by frost damage.     

Water relation patterns of bare-root and container jack pine and black spruce seedlings planted on boreal cut-over sites

Water relation patterns and subsequent growth were studied on bare-root and container jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) B.S.P.) seedlings during the first growing season on boreal cut-over sites.Containerized seedlings of both species had greater needle conductance compared to bare-root seedlings over a range of absolute humidity deficits. Needle conductance of containerized seedlings in both species remained high during periods of high absolute humidity deficits and increasing plant moisture stress. Bare-root seedlings of both species had a greater early season resistance to water-flow through the soil-plant-atmosphere continuum (SPAC) than container seedlings. Resistance to water flow through the SPAC decreased in bare-noot seedlings of both species as the growing season progressed, and was comparable to container seedlings 9 through 14 weeks after planting. Four weeks after field planting jack pine container seedlings had greater new root development compared to bare-root seedlings, while at the end of the summer both stock types had similar new root development. Black spruce bare-root seedlings had greater new root development compared with container seedlings throughout the growing season.     

Vegetative propagation studies of gum arabic trees. 2. The vegetative propagation of adult Acacia senegal

Vegetative propagation of Acacia senegal is possible from branch fragments taken from the crown of mature trees (13 years old), without causing ortet destruction.The most responsive planting stock is taken from cuttings 15 cm long (with 12 to 15 nodes) and a diameter of 10 ± 6 mm (wood of 2 to 4 years old). With this material, the ablation of the leaves prior to planting is a factor which furthers development of the cutting's root system.The development of the root system is also highly influenced by the time at which the cutting is taken: results vary from 10% during the dry season to more than 70% during the rainy season (June—October).Cuttings can be taken from branches 50 cm long. It is thus possible to preserve the planting stock for 8 days in a continually humidified jute cloth and then to make the cuttings at the time of establishment in a nursery, without changing their rhizogenic aptitude.The cuttings show characteristics of maturity (slow growth, plagiotropy, fructification). It is nevertheless possible to preserve the collected genotypes in the field, or better, in planting pots in the nursery, so as to further the process of physiologic rejuvenation with the aim of in vitro cloning.researcher at CIRAD/C.T.F.T., detached to ISRA/D.R.P.F.     

Scots pine stand establishment with special emphasis on uncertainty and cost-effectiveness,the case of northern Finland

The effect of uncertainty on the cost-effectiveness of alternative chains of stand establishment in northern Finland was examined. The data were from a reforestation study of Scots pine (Pinus sylvestris L.) consisting of 288 sample plots, which were measured with respect to regeneration success. The study design included four site-preparation methods (patch scarification, ploughing, prescribed burning and disk trenching) combined with three reforestation methods (sowing, planting with containerized seedlings and planting with bare-rooted transplants). Initial reforestation density was 2,500 spots or seedlings per hectare, and the regeneration success was modeled as probability with two thresholds, namely 500 and 1,100 saplings. On formerly spruce-dominated as well as pine-dominated sites the most cost-effective chain was ploughing and planting with containerized seedlings, when threshold was 1,100 saplings per hectare. However, with threshold of 500 saplings the best performer was ploughing and direct sowing on both sites.     

Model development for evaluating planting-stock production options in Ontario

As a prelude to modeling regeneration in Ontario, the model STOCK was developed to assist forest nurserymen in evaluating their planting-stock production options. STOCK simulates the growth and survival of seedlings from seed-source selection to fully grown planting stock. The effects of various management options and cultural treatments (such as seed source, stock type, fertilization, thinning and pruning) on growth and survival may be simulated in accordance with empirical models or the user's expectations in the form of simple coefficients or improvement factors. The model simulates various stock-production options in accordance with the user's choices then optimizes the results on the basis of a calculated cost-efficiency index (CEI). In effect, CEI combines the total cost and stock production with growth, survival and the quality of the resulting planting stock. The model is written in both the FORTRAN 77 standard and in Apple BASIC.     

不同类型薄壳山核桃苗木栽植效果研究

以淮安地区种植园的1年生和泰州地区种植园的2年生‘波尼’薄壳山核桃苗为试材,研究裸根苗、土球苗、无纺布容器苗等3种不同类型薄壳山核桃苗栽植后生长发育的差异。结果表明:3种类型苗木栽植后新梢和根系生长差异较为显著。两处均以无纺布容器苗成活率最高,达到100%;新梢生长量最大,1年生和2年生苗木的生长量分别为110.77 cm和53.44 cm;根系也最为发达。土球苗次之,裸根苗的新梢、根系生长量最小。分析表明,在江苏淮安和泰州这两个地区,无纺布容器苗的成活率、平均新梢生长量、分枝数、总的新梢生长量、主根长度、粗度、侧根数量等均优于土球苗和裸根苗的。此外,3种类型苗木栽植后,2年生苗木的地上、地下部分生长均优于1年生苗木的。