Relative contribution of initial root and shoot morphology in predicting field performance of hardwood seedlings

Single and multiple linear regression techniques were used to explain the capacity of initial seedling root volume (Rv) and first-order lateral roots (FOLR) relative to shoot height, diameter, and fresh mass to serve as important indicators of stock quality and predictors of first- and second-year height and diameter on an afforestation site in southern Indiana, USA. This was accomplished for northern red oak (Quercus rubra L.), white oak (Quercus alba L.), and black cherry (Prunus serotina Ehrh) seedlings graded into four Rv categories at establishment. Field survival was high (85–97%) for all species. Initial diameter, height, fresh mass, and Rv provided similar predictive ability of second-year field response for absolute height (R² = 0.59–0.77) and diameter (R² = 0.50–0.73) for both oak species. Initial seedling Rv was a better predictor of field response than FOLR for both oak species, though not for cherry. Multiple-variable models accounted for a greater proportion of the total variation in seedling field height and diameter than did single-variable equations. The high R² (up to 0.95) of regression models suggests field performance of these species can be reliably predicted and confirms the importance of initial seedling morphology in dictating early plantation performance.     

Root system morphology of Quercus rubra L. planting stock and 3-year field performance in Iowa

On 3 sites, 3-year performance of 1+0 northern red oak (Quercus rubra L.) seedlings was evaluated with respect to initial root system grade. Seven hundred twenty nursery-run bareroot northern red oak seedlings were graded according to numbers of large (>1mm) first-order lateral roots and outplanted in spring 1987 on eight 90-tree plots distributed among three sites in central Iowa. Survival, height growth, and diameter growth were significantly greater for seedlings with 10 or more large first-order lateral roots than for seedlings with 4 or fewer. Seedling survival and growth were significantly and positively related to initial root grade. First-year height growth, however, was significantly and negatively correlated with initial height. Combined results for seedling survival and growth indicated that red oak seedlings with five or more large first-order lateral roots have a greater probability of success both in terms of survival and early growth than do those with four or fewer first-order lateral roots.Journal paper no. J-15193 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project no. 2485.     

Sowing methods and mulch affect 1+0 northern red oak seedling quality

The effects of sowing depth, seedling density and mulches on northern red oak seedling survival and growth were evaluated in Wilson State Forest Nursery in southwest Wisconsin, USA. Sowing depths between 2.2 and 6.3 cm, combined with sowing densities of 75 and 150 acorns · m^-2, made up five sowing method plots. Mulch treatments of ground corncobs aged 1 year, hardwood sawdust aged 2 years, and no mulch made up 3 subplot treatments. Treatments resulted in a range of densities from 18 to 148 seedlings · m^-2. Mulch delayed emergence and increased seedling survival. Increasing sowing depth also delayed emergence. Corncob mulch increased root collar diameter; however, hardwood sawdust, aged for 2 years, decreased both root collar diameter and the number of permanent first-order lateral roots. Increasing sowing depth decreased root dry mass but increased shoot dry mass. Increasing density from 18 to 148 seedlings · m^-2decreased root dry mass in this study.     

Organic Matter Added to Bareroot Nursery Beds Influences Soil Properties and Morphology of Fraxinus pennsylvanica and Quercus rubra Seedlings

Bareroot hardwood seedling production involves intensive soil management. To increase soil organic matter (OM), nurseries commonly grow a cover crop for 1 year after every 1–2 year of seedling production. Raising soil OM levels can also be achieved through addition of soil amendments. We studied the influence of chicken manure (CM) and composted leaf, tree, and lawn trimmings (Cp) on soil properties and morphology of green ash (Fraxinus pennsylvanica Marsh.) and northern red oak (Quercus rubra L.) seedlings. CM was applied at 725, 1450, or 2900 kg ha⁻¹ (CM725, CM1450, and CM2900, respectively) and Cp was applied at 200 m³ ha⁻¹. Addition of CM and Cp significantly raised soil OM levels and altered soil chemical properties compared to the control (Ctrl). Root-collar diameter increased with addition of CM1450, CM2900, or Cp compared to CM725 or Ctrl plots for northern red oak, but was largest in soils amended with CM2900 for green ash. Conversely, height was greatest with addition of CM725 for northern red oak, but green ash seedlings were shorter in Ctrl plots than in all amendments except for CM725. Root volume of green ash and northern red oak seedlings was positively influenced by addition of CM or Cp. Seedling responses to nursery soil amendments vary with different forms and amounts of OM. Benefits to seedling growth through application of appropriate materials in the proper balance can improve seedling morphological quality and positively influence soil chemical properties.     

Nursery stock quality as an indicator of bottomland hardwood forest restoration success in the Lower Mississippi River Alluvial Valley

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.     

Inoculation of fumigated nursery soil increases nodulation and yield of bare-root red alder (Alnus rubra Bong.)

To determine if inoculation increases nodulation and yield of bare-root red alder (Alnus rubra Bong.), fumigated nursery plots were treated with inoculum and ammonium sulfate (28 kg N ha^–1) in a factorial experiment. Inoculum was alder soil with 100 infective units of Frankia g^–1. Seedlings were evaluated for nodulation at age 10 wk and when lifted, at age 9 mo. Inoculation produced earlier and more extensive nodulation and increased seedling root collar diameter, height, and dry weight. Fertilization decreased seedling height, but did not decrease nodulation. No interaction of fertilization with inoculation was found. Inoculated unfertilized plots had the highest yield of packable seedlings (257 m^–2), and uninoculated fertilized seedlings had the lowest yield (126 m^–2).     

Survival and competitiveness of Quercus rubra regeneration associated with planting stocktype and harvest opening intensity

Successful regeneration of northern red oak (Quercus rubra L.) on productive sites is problematic in eastern North American forests. Natural and artificial regeneration often cannot compete with fast-growing, shade intolerant species such as yellow-poplar (Liriodendron tulipifera L.). This study examines 5-year survival, growth, and competitive ability of planted northern red oak seedlings in various group selection harvest sizes in south-central Indiana, USA. Seedling stocktypes consisted of high (BHD; 75 seedlings m^?2) and low (BLD; 21 seedlings m^?2) nursery-bed-density bareroot seedlings, and small (CS; 11.4 L) and large (CL; 18.9 L) container seedlings. Group selection openings included large (0.400 ha), medium (0.100 ha), and small (0.024 ha) circular gaps in four stands. Larger stocktypes and gap sizes improved seedling height, diameter, and growth; ANOVA indicated only gap size was significant for seedling survival. Logistic regression showed survival was positively correlated to diameter at year 1, and aspect, gap size, and stocktype were significant predictors of survival. Our data indicated no differences in density of natural regeneration among gap sizes, although trends suggest greater numbers of bigger competitors in larger gaps sizes. Yellow-poplar regeneration was the tallest competitor of more than 50% of all northern red oak seedlings. Competitive status of seedlings after 5 years differed only by stocktype, with large container stock in a better competitive position than bareroot stock. However, less than 20% of seedlings in all stocktypes in each gap treatment were considered competitive (i.e., ≥80% of the height of tallest competitor) against their tallest competitor. The use of larger planting stock may offer greater opportunities for successfully regenerating northern red oak seedlings on productive sites but likely would have to be accompanied by treatments to reduce woody competition.     

核桃幼树内源激素与生长势的关系

激素在果树生长发育过程中起着重要调控作用,基因通过激素控制植株高矮(曾骧,1992).对苹果(Maluspumila)、李(Prunus salicina)、桃(Prunus persica)等果树内源激素与生长势的关系已有一些报道(王丽琴等,2002;周怀军等,2002;孙艳香等,2001),但在核桃上有关研究尚少.本试验以核桃(Juglans regia)不同品种的嫁接植株及实生苗为试材,探讨内源激素与树体生长势的关系,为选择核桃矮化砧木提供理论依据.     

红松苗龄型对苗木质量和造林效果的影响

以春季播种、2年生红松苗(S2-0),春季播种、2年后移栽、再培育1年的3年生红松苗(S2-1),春季播种、2年后移栽、再培育2年的4年生红松苗(S2-2)、秋季播种、2年生红松苗(F2-0)为对象,研究不同苗龄间苗木质量和造林效果的差异。结果表明:与S2-0相比,S2-1苗高、地径、FOLR、单株生物量分别增加100%,108.2%,100%和398.4%,单株氮、磷、钾含量分别增加368.6%,646.2%和349.3%;S2-0造林成活率仅为67.5%,S2-1比S2-0造林成活率提高20.6%。S2-0移栽2年后,苗木质量提升幅度较移栽1年小;S2-2与S2-1造林成活率、地径生长量无显著差异。F2-0的苗高较S2-0大35.4%,造林成活率提高5.6%,秋季播种红松可促进苗木质量的提高。S2-2,S2-1,S2-0,F2-0的FOLR分别为18,14,7和7,FOLR与造林成活率、苗高、地径均显著相关,FOLR是评价红松苗木质量的简易、可靠指标。     

Pisolithus tinctorius increases the size of nursery grown red oak seedlings

Inoculation of nursery beds with vegetative mycelia of P. tinctorius (Pt) significantly increased the number of salable 1–0 red oak seedlings produced in two of three years and the average stem height and diameter each year. The percentage of Pt mycorrhizal primary lateral roots on seedlings in the inoculated plots was significantly correlated with stem diameter and weight of lateral roots. The high rates of colonization of short roots by Pt in inoculated plots suggested the test fungus could successfully compete with indigenous fungi in forming mycorrhizae.     

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.     

Underplanting Cherrybark Oak (Quercus pagoda Raf.) Seedlings on a Bottomland Site in the Southern United States

We initiated a study on a bottomland site in the southern United States to examine the effects of Japanese honeysuckle (Lonicera japonica Thunberg) control and seedlings of two root classes on survival and growth of underplanted cherrybark oak (Quercus pagoda Raf.) seedlings. Three honeysuckle control treatments were assigned to nine 0.5-ha plots in a stand harvested to 30% residual stocking. Treatments included a spring 1997 herbicide application (Escort^®, metsulfuron-methyl), a similar application in the late summer of 1997, and a control (no herbicide application). In 1998, half of each treatment plot was planted with seedlings having four or more first-order lateral roots > 1 mm in diameter, while the other half of each plot received seedlings with fewer than four lateral roots. Four years after treatment, the early season application reduced honeysuckle biomass 60% relative to the other treatments, but we did not observe a survival or growth response by underplanted seedlings. Three years after establishment, seedlings that initially had four or more lateral roots were 16% taller and 18% larger in root-collar diameter than seedlings in the other class, but these differences were primarily due to initial size differences maintained through the study period. Over all treatments, oak seedlings averaged 87% survival while showing a 300% increase in height and a 170% increase in root-collar diameter 3 years after planting. Our results suggest that partial stand harvesting followed by underplanting may be a viable approach for establishing cherrybark oak reproduction on bottomland sites of the southern United States.     

The effect of scalping on seedling establishment after seed tree cutting of Scots pine stands in drained peatlands in northern Finland

We studied the establishment of natural seedlings after seed tree cutting and scalping in two drained Scots pine peatland stands in northern Finland (Simo and Sievi). Approximately, 50?ha^?1 of Scots pine stems were retained on both sites. During the six subsequent years, five seedling surveys were conducted. The effect of site preparation was analysed using generalized linear mixed models (GLMM). The mean density of pine seedlings increased more quickly in the scalped plots and was ca. 1.1?m^?2 after six years compared to 0.87?m^?2 in the non-scalped plots, on average. Scalping increased the number of pine seedlings 2-fold compared to that in non-treated plots in Simo, however, in Sievi non-treated plots had 30% higher pine seedling density after six years. Downy birch seedling density was 9–10-fold compared to that of non-treated plots in both sites. In terms of seedling density, seed tree cutting led to satisfactory pine regeneration after just two growing seasons in drained pine peatlands, even without scalping. Scalping significantly increased the number of pine seedlings, but it also enhanced the germination of birch seedlings strongly.     

Morphological indicators of stock quality and field performance of red oak (Quercus rubra L.) seedlings underplanted in a central Ontario shelterwood

The value of initial stem diameter near the root collar, shoot length and number of first-order lateral roots (FOLR) as morphological indicators of stock quality and field performance was examined for bareroot (1+0, undercut) red oak (Quercus rubra L.) underplanted in a shelterwood in central Ontario. These three attributes were measured on more than 400 seedlings prior to planting, and their relationship with height and basal diameter growth two years after planting was determined using correlation and regression analysis. Initial diameter, shoot length and number of FOLR were positively and significantly correlated with second-year height and diameter. These relationships were strongest for diameter, but this variable explained less than 25% of the total variation in growth. Of the three indicators, diameter was also the best predictor of several physical characteristics of root systems two years after planting. Initial diameter was significantly correlated with root volume, root area and lateral root, taproot and total root dry mass. Weaker relationships existed between initial shoot length and number of FOLR and second-year root system features. Stem diameter two years after planting was more strongly related to root volume, area and dry mass than was initial diameter, the probable result of adjustment in root-shoot balance of planting stock to the shelterwood environment.     

不同施肥处理对美国红橡木幼苗生长的影响

对红橡木幼苗进行了不同施肥处理试验,结果表明:施肥显著促进红橡木苗高和地径生长.不同处理比较,T4处理(基质拌入1%NPK复合肥)最好,其苗高、地径均较大,分别比对照高39.3%和33.3%,T1(N肥)处理次之,其苗高、地径比对照高28.6%和27.4%.不同施肥处理对红橡木苗高和地径生长的影响效应从大到小的顺序为:...     

Modifying the microclimate around young oaks through vegetation manipulation: Effects on seedling growth and branching

The objective of this research was to evaluate the influence of vegetation control on the microclimate (light, air temperature, vapor-pressure deficit (VPD)) and on the growth of young planted, sessile oak seedlings. Three types of vegetation control, creating a range of above-ground interaction intensity, were compared. In the open treatment, vegetation was chemically controlled and was maintained at a low height; in the closed treatment, vegetation was manually controlled and a few dominant individuals that overtopped the oak seedlings were cut; and in the sheath treatment, the vegetation in a 0.5-m diameter circle around each seedling was manually cut to a height equal to three quarters of the total seedling height. In all treatments, a strong reduction of incoming radiation was observed, as well as an increase in air temperature and VPD during the day, and a decrease in daily PET, compared to the reference located 4 m above the vegetation. However, the neighboring vegetation did not modify the microclimate around the seedling to a level that could have induced a significant reduction in seedling photosynthesis and, thus, in seedling growth. Seven years after planting, seedlings were shortest in the open treatment and tallest in the closed treatment (334, 372, 378 cm in the open, sheath and closed treatments, respectively). Seedlings in the open treatment allocated proportionally more biomass to diameter increment than to height growth, compared to seedlings in the sheath and closed treatments. The seedlings averaged 1.77, 1.10 and 1.00 forks in the open, sheath and closed treatments, respectively, and the average height of the lowest fork was 171, 206 and 226 cm in the same treatments. The reduction of the number of forks per seedling was not related to a reduction of the appearance of new forks, but rather to a reduction in the persistence of the existing forks. These changes in stem allometry and in fork development seemed to be related to the lateral shade afforded by the vegetation.     

Effects of treeshelters and polyethylene mulch sheets on survival and growth of cork oak (Quercus suber L.) seedlings planted in northwestern Tunisia

Success of plantation establishment depends on the ability of seedlings to withstand animal browsing and competition from vegetation. This study in northwestern Tunisia examined the influence of browsing protection and vegetation control on seedling mortality, diameter, and height growth components of an evergreen sclerophyllous oak species, cork oak (Quercus suber L.) for the first 2 years after planting (2005 and 2006). Browsing protection was controlled by varying both treeshelter type (non-vented, vented, and control) and height (1.2-m and 1.8-m tall). Competing vegetation was controlled through increasing sizes of square-shaped black polyethylene mulch sheets: 0 m, 0.7 m, 1 m and 1.3 m large. Seedling mortality rate was relatively low during the first year (9%) and was not affected by any of the studied factors. During the following year, mortality was lower for seedlings in both types (non-vented and vented) of 1.2-m tall treeshelters than for unsheltered ones. Mortality was only slightly higher for 1.8-m tall shelters than for 1.2-m shelters. Compared to unsheltered seedlings, basal diameter was reduced during both seasons for seedlings inside non-vented treeshelters (1.2-m and 1.8-m tall), whereas for vented shelters it was reduced during the first year and then increased during the second year. Height growth was positively affected by tree shelters during both years. Seedlings inside non-vented 1.8-m tall shelters were the tallest having an average height of up to 140 cm at the end of the second year, while the unsheltered seedlings had only an average height of up to 42 cm. The greater height of the sheltered seedlings was attributed to the increase of: (1) the number of shoot flushes yearly established on the main stem (up to three), and (2) the length of all the growth units produced during each flush. Seedlings inside vented shelters had balanced growth with a low proportion of seedlings unable to support themselves without a stake (7%). However, non-vented shelters had unbalanced height and diameter growths resulting in both a higher height-to-diameter ratio and in a higher proportion of seedlings having stability problems (47%). Polyethylene mulch sheets did not affect early survival, seedling basal diameter, or number of shoot flushes established yearly, but did slightly improve seedling height at the end of the second season, mostly due to the significant improvement in shoot elongation of the first flush. Results suggest that both 1.8 m treeshelters and plastic mulches may enhance the growth of cork oak seedlings planted on harsh sites in northwestern Tunisia.     

不同炼苗密度对桉树轻基质幼苗的影响

通过对5个月生4种不同炼苗密度的尾巨桉优良无性系 DH_32-29幼苗树高、地径及各器官生物量进行调查分析，结果表明：4种不同炼苗密度间苗高无显著差异；而地径差异达到极显著水平，并呈极显著负相关；不同炼苗密度单株间及各器官生物量均差异显著，单株生物量、叶片、茎干与根系的生物量均随炼苗密度增加而降低；考虑到空间利用率、通风保水性及疾病易感程度综合分析，炼苗密度以45株·盘^-1效果最佳。     

Growth and biomass production in Azadirachta indica seedlings in response to nutrients (N and P) and moisture stress

Production of quality seedlings is an important aspect of successful tree planting. No information is available on the effect of nutrients and water on the growth and development of the seedlings of neem (Azadirachta indica A. Juss), an important component of many tropical agroforestry systems. In an experiment in central India, the growth and nutrient-use efficiency of neem seedlings grown at various levels of light, nutrients (N and P), and water stress were determined. Seedlings were given light (diffused and complete) and nutrient (N and P) treatments comprising either high N-high P, high N-low P, low N-high P, or low N-low P. Seedlings grown in complete light (800 mol/m²/s) had four times more biomass than those grown in diffused light (200 mol/m²/s). Significant increase in seedling biomass was observed with nitrogen application, while phosphorus had no effect on biomass. Leaves contributed maximum biomass, followed by roots and stem. Nutrient use efficiency decreased with an increase in the supply of nutrients. In another experiment, containerized and bare-root seedlings were subjected to five watering treatments, viz., watering twice a week, watering weekly, watering every alternate week, watering every third week, and natural precipitation. Plant moisture stress affected both growth and survival of neem seedlings. Only 50 per cent of seedlings survived in severe drought treatment (no. 4) whereas 90 to 95 per cent seedlings showed growth in all other treatments. Plant moisture stress in severe drought treatment averaged –21 bar while in other treatments it ranged from –9 to –12 bar. Shoot-root ratio was high in bare-root seedlings as compared to containerized seedlings. Containerized seedlings had shown better endurance against drought than the bare-root seedlings. The results suggest that neem seedlings adjust their nutrient use efficiency and can be grown even under limited available resources. It is also inferred that the species can tolerate soil resource depletion caused by competitor species.This revised version was published online in November 2005 with corrections to the Cover Date.     

Tree Regeneration and Sapling Damage of Pedunculate Oak Quercus robur in a Grazed Forest in Galicia, NW Spain: A Comparison of Continuous and Rotational Grazing Systems

Forest grazing has been recognised as being a useful tool in fire-risk reduction, in addition to having the potential to preserve or enhance forest biodiversity if managed correctly. Concern for natural regeneration of forest trees in Europe has also prompted interest in the effects of large herbivores on seedling and sapling growth and mortality. An investigation was carried out into sapling damage and density of natural regeneration of oak (Quercus robur) in a mature, pony-grazed, Pinus radiata forest in Galicia, NW Spain under two different grazing regimes (continuous and rotational). In all treatments significantly more oak seedlings and saplings were recorded in areas of grass sward than areas dominated by taller ground flora species. Damage to oak saplings was assessed from the form (height and canopy) relative to stem diameter. The height and average canopy diameter of similar-aged saplings were found to be significantly greater in ungrazed (control) than both continuous and rotationally grazed treatments. Height and canopy diameters of similar-aged oak were not significantly different between the two grazing treatments. Significant differences were observed in tree form, with unbrowsed saplings having the greatest height to canopy width ratio and those in the continuously browsed plots having the smallest. An obvious decrease in the goodness of fit (R²) of regression analyses were found in continuously grazed areas compared to rotational and control plots for both height and canopy data. The differences in damage observed were not significantly different enough to suggest one method of grazing over the other as being better for minimising sapling damage. Management requirements are more likely to dictate grazing regime. Overall, stock density is likely to have a more significant effect on damage than stocking system.