Site preparation of abandoned fields and early establishment of planted small-sized seedlings of silver birch

Field experiments at two sites in Sweden investigated the possibility of establishing silver birch (Betula pendula Roth) on abandoned fields by planting small (5–10 cm tall) seedlings. The effects of five modes of soil preparation (no preparation, rotary cultivation, deep ploughing, soil inversion, and removal of topsoil) with or without preliminary herbicide weed control on seedling performance were studied for three growing seasons following plantation. Both a split-plot design and a randomized block design were used to evaluate the experiments. Where there was no site preparation, seedling survival was close to nil. The highest seedling survival rates on the site with sandy soil were obtained on sites prepared by removing topsoil, or by transposing it by deep ploughing. On the site with silty soil, the best survival was observed on sites created by soil inversion or rotary cultivation. The tallest seedlings were found on sites with topsoil retained within the soil profile. Herbicide application with glyphosate promoted seedling survival and seedling height in combination with no soil preparation, but was of little effect when followed by mechanical soil preparation.     

Economic returns from enhancing loblolly pine establishment on two upland sites: Effects of seedling grade,fertilization, hexazinone,and intensive soil cultivation

On two well drained Coastal Plain sites, early (4-year) and mid-rotation (12-year) performance of loblolly pine (Pinus taeda L.) was examined in relation to mechanical site preparation, herbaceous weed control, and fertilization with diammonium phosphate (DAP). In addition, seedling grade as determined by groundline diameter (GLD) was a fourth factor evaluated. Of the four factors examined, seedling grade was the only factor to consistently improve fourth-year survival. In Alabama, seedlings with a 2.5 mm GLD averaged 62% survival while 5.1 mm seedlings averaged 83% survival. In Virginia, 1.3 mm seedlings had 73% survival and 5.1 mm seedlings had 79% survival. Calculated volume gains from increasing seedling grade suggest that a 1 mm increase in GLD could amount to an additional 7 to 12 m³/ha at age 12. Seedling size and mechanical site preparation were partly exchangeable in influencing survival and growth. Use of hexazinone on late planted seedlings increased mortality at both sites. Applications of hexazinone increased volume/ha when combined with DAP fertilization. Fertilization with DAP increased 12-year volume/ha only when weeds were controlled with hexazinone or disking.Alabama Agricultural Experiment Station Journal Series No. 9-933657.     

深山含笑3年生苗木移栽技术初探

通过不同季节，不同移栽技术处理试验，结果表明：3月底至4月初（清明节前）是深山含笑3年生苗的移栽适期，剪除全株叶片和留存叶基约1／4叶片的裸根苗移栽成活率分别达到97．2％和98．8％，留存部分叶片对移栽苗尽快恢复生长有好处，4月中，下旬移栽则应选择保水性能较好的土壤（如黄泥土）作圃地，剪除全株叶片和留存叶基约1／4叶片的裸根苗移栽成活率分别达到了96．6％和97．2％，如在保水性能较差的砂质土中移栽，则应剪除全部叶片，梅季移栽需坚持带土并剪除全部叶片，成活率可达90．67％，如在移植苗上方搭棚遮荫，则成活率可提高到95．33％，裸根和裸根打泥浆移栽的效果都很差，成活率在50％以下。     

Relating the survival and growth of planted longleaf pine seedlings to microsite conditions altered by site preparation treatments

Pine plantations in the southeastern United States are often created using site preparation treatments to alleviate site conditions that may limit survival or growth of planted seedlings. However, little is understood about how site preparations affect longleaf pine (Pinus palustris P. Miller) seedlings planted on wet sites. In a 2-year study (2004 and 2005) on poorly drained, sandy soils of Onslow County, North Carolina, we examined the effects of common site preparation treatments on microsite conditions and quantified relationships between microsite conditions and longleaf pine seedling survival and growth. Treatments used in the study included site preparations designed to control competing vegetation (chopping and herbicide) combined with those that alter soil conditions (mounding and bedding). During both years, mounding and bedding treatments reduced the amount of moisture within the top 6 cm of soil and increased soil temperatures when compared to flat planting (p < 0.001). Soil moisture was inversely related to seedling mortality in 2004 (r² = 0.405) and inversely related to root collar diameter in 2005 (r² = 0.334), while light was positively related to root collar diameter in 2005 (r² = 0.262). Light availability at the seedling level was highest on treatments that effectively reduced surrounding vegetation. Herbicides were more effective than chopping at controlling vegetation in 2004 (p < 0.001) and 2005 (p = 0.036). Controlling competing vegetation, especially shrubs, was critical for increasing early longleaf pine seedling growth.     

Effects of full and partial clearing, with and without herbicide, on weed cover, light availability, and establishment success of white ash in shrub communities of abandoned pastureland in southwestern Quebec, Canada

Shrub communities established on former pasture land are currently under-used and their forestry potential is of interest to land owners wishing to increase valuable hardwood regeneration on their properties. The comparative effects of strip clearing and total clearing, both treatments applied with or without herbicide, on competing vegetation cover, light availability, and survival and growth of planted white ash (Fraxinus americana L.) were examined in two different shrub dominated sites for 3 years in southwestern Québec, Canada. Survival was high in all treatments. At the site with the richest soil and in comparison to total clearing, strip clearing produced the lowest light level in the third year, which induced lower total herbaceous weed cover. These combined effects produced the same growth results for white ash seedlings in all treatments. At the second site, with the highest woody vegetation regrowth, strip clearing has promoted seedling height growth and produced the highest height: diameter ratio for white ash. This ratio was also superior at this site in the absence of herbicide. Treatment effects were soil/site dependant. Because partial clearing in strips has never reduced tree growth in comparison to total clearing, it represents a promising method for the establishment of valuable hardwoods in shrubby vegetation, with lower management intensity and lower landscape impact than total clearing.     

Eight-year performance of bareroot Douglas-fir and bareroot and plug western larch Seedlings following herbicide applications,northeast Oregon,USA

Plantation success in northeastern Oregon can be limited by poor survival for western larch (Larix occidentalis Nutt.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco) seedlings. Vegetation management treatments may increase soil moisture availability during the dry summer months, thereby increasing the probability of seedling survival. Chemical site preparation treatments were applied in spring 2007, summer 2007, and spring 2008 to determine if such treatments would improve survival and growth of bareroot Douglas-fir and bareroot and plug western larch seedlings on three sites near Elgin, Oregon. Although some herbicide treatments significantly increased survival, results were not consistent among sites. Overall, Douglas-fir had greater survival after 7–8 years than larch seedlings. Seedling size 7–8 years after planting was also highly variable among sites and treatments with larch seedlings being taller and larger than Douglas-fir seedlings, on the average. Size for all stock types was negatively correlated with vegetative cover and positively correlated with first-year soil moisture. Macro- and microclimatic conditions, including topography and soil depth, were likely contributors to differences in survival and growth.     

Interactions between soil scarification and Norway spruce seedling types

Interactions between scarification treatments and seedling types of Norway spruce were examined at two different locations in southern Sweden. The scarification treatments were not scarified control, mounding and soil inversion and the seedling types were a 10 week-old containerized seedling (mini seedling), a 2 year-old containerized seedling and a 2 year-old hybrid seedling, grown as a containerized seedling the first year and as a bare-root seedling the second year. Site preparation intensity had a greater effect on the mini seedlings. The results indicated that mini seedlings established faster in the soil inversion treatment compared to the larger seedling types. At the same seedling age, the mini seedlings had faster or similar growth rate as the containerized and the hybrid seedlings regardless of scarification treatment. Although mini seedlings grew as well as or even better than larger seedlings if they were successfully established, they were more sensitive to their planting environment and proper handling was critical. Problems with frost heaving and competing vegetation have to be taken into consideration when choosing site preparation method and seedling type.     

苦槠混交林营造技术初探

采用苦槠裸根苗、容器苗在不同立地条件下与桂花、杉木、木荷进行混交造林试验,连续2 a的观测结果表明:苦槠容器苗的造林成活率、树高、地径生长量均比裸根苗高;Ⅰ级地苦槠的造林成活率、树高、地径生长量均比Ⅱ、Ⅲ级地高。说明营建苦槠人工林选择立地条件较好,采用容器苗造林较为适宜。     

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.     

Effect of shading,mulching and vegetation control on Douglas-Fir seedling growth and soil water supply

Harsh environmental conditions on many harvested sites in southwest Oregon necessitate site modifications for successful regeneration of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco]. We conducted a 2-year study with 350 seedlings to assess the effects of twelve soil-shading, mulching, and vegetation control techniques on seedling growth and soil temperature and moisture environments. Treatments modified a variety of environmental conditions. Major effects of treatments were to lower soil surface temperature, reduce soil surface evaporation, and reduce vegetative competition for soil water. These modified conditions affected seedlings by adjusting the timing of seedling growth and reducing soil water loss to increase available water for seedling use. Final seedling shoot volume and stem diameter both differed among treatments. Seedlings in treatments where competing vegetation was controlled showed significantly greater growth than seedlings in other treatments. Soil water loss in treatments where either soil surface evaporation was controlled by mulching, or where competing vegetation was controlled, was significantly less than water loss from the shaded and control treatments. Soil water loss in treatments with vegetation controlled by herbicide was significantly less than in treatments with vegetation controlled by scalping. Seedlings showed greatest growth with treatments that elicited the most efficient use of available microsite water either by reducing soil surface evaporation or vegetation competition.     

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.     

Root characteristics and growth potential of container and bare-root seedlings of red oak (<Emphasis Type="Italic">Quercus rubra</Emphasis> L.) in Ontario,Canada

Root characteristics and field performance of container and bare-root seedlings of red oak (Quercus rubra L.) were compared during the first growing season after planting. Sixty seedlings of each stock type were planted on a clearfell and weed-free site near Restoule, Ontario. Twenty-four additional seedlings from each stock type were compared at the start of the study in terms of shoot and root parameters. Measurement of root and shoot parameters were repeated at three dates during the first growing season in the field. The root systems of container stock had a larger number of first order lateral long roots and were significantly more fibrous than bare-root stock. These differences were sustained throughout the first growing season. In terms of field performance, container seedlings had 100% survival and achieved significant increases in both biomass and shoot extension. Bare-root seedlings suffered 25% mortality, significant shoot dieback and more variable growth. The mean relative growth rate (RGR) of container seedlings increased throughout the study period to a maximum of 30 mg/g/day, whereas the mean RGR of bare-root stock remained close to or below zero. Overall, the container seedlings proved less prone to transplanting shock than the bare-root seedlings, most likely due to favourable root architecture and the pattern of root development. Further work may be warranted in container design, growing regimes and root architecture to fully realise the potential of container systems for the production of high quality red oak seedlings across a range of site conditions.     

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 influence of silvicultural treatments and site conditions on American chestnut (Castanea dentata) seedling establishment in eastern Kentucky, USA

After more than 50 years of research and selective breeding, blight-resistant American chestnut (Castanea dentata) trees will soon be available for planting into the species’ pre-blight range. Increased understanding of the regeneration requirements of pure American chestnut (C. dentata [Marsh.] Borkh.) will increase the success of future efforts to establish blight-resistant chestnut. We quantified survival and initial growth of bare-root American chestnut seedlings at five locations in eastern Kentucky, USA. We used a split-plot design to compare seedlings planted within adjacent mesic and xeric sites treated with either a two-age shelterwood overstory treatment or a midstory removal treatment. The silvicultural treatments and topographic settings allowed us to evaluate chestnut seedling performance under four light and site productivity combinations. Seedling survival was 57% and seedling height averaged 94 cm following two growing seasons. Seedling survival was negatively related to sand and coarse fragment content, but was unrelated to silviculture treatment or topographic position. Chestnut seedlings grew best in shelterwood overstory treatments areas on mesic sites. Seedlings growing in shelterwood overstory treatment areas added 3- and 3.5-times more height and stem increment compared to seedlings planted after midstory removal. Seedling leaf mass and foliar nitrogen (N) content were also greatest in shelterwood plantings on mesic sites. The high-light environment created by shelterwood overstory removal resulted in better initial seedling growth, but the moderate-light of the midstory removal treatment may ultimately provide chestnut seedlings a greater advantage over competing vegetation.     

Effects of soil water content and initial root volume on the nutrient status of 2+0 Douglas-fir seedlings

Two-year-old bareroot Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco.) seedlings were graded on the basis of four root-volume categories and transplanted to four moisture-stress treatments (6, 12, 18, and 24% soil water content) in pots. Macronutrient concentrations and contents of both old and new foliar tissue were determined. Decreasing soil water content resulted in higher concentrations of phosphorus, potassium, and particularly nitrogen in both old and new foliar tissue. This can be attributed to reduced growth, translocation, metabolic activity, and nutrient requirement in response to moisture stress. Seedlings with relatively higher root volumes exhibited higher nutrient concentrations and contents, as well as increased growth. Thus, increased total root biomass per unit of soil area with increasing seedling root volume may have resulted in greater nutrient use, supply, uptake, and storage.     

The susceptibility of white spruce seedlings to overwinter injury and their post-injury field responses

Foliar and stem injury was assessed in white spruce (Picea glauca (Moench) Voss) seedlings planted in the spring and in the summer of 1992 and injured during their first overwintering on two sites in the southeastern boreal forest of British Columbia. Freeze-desiccation appears to be the main cause of the injury. Seedlot effect on the injury was significant, while planting time effect was not. Although the seedlot effect may be confounded with stock-type effect, analyses indicated increasing injury with increasing seedling height and declining ground-level diameter. Seedling vigour (height and diameter increments in the previous growing season) was also significantly related to the injury which increased with increasing vigour but the significance of this relationship varied from site to site. Condition of injured seedlings generally declined further during the post-injury growing season. This decline was greater in spring-planted than in summer-planted seedlings. Excavated root systems of container-grown seedlings showed the majority of post-planting root growth originating from the bottom-third of the nursery-container plug, deeper than 10 cm from the soil surface. This is seen as a factor potentially contributing to desiccation injury as the soil in the geographic region often remains frozen at these depths long into spring.     

Seedling demography and establishment of Cryptomeria japonica in a cool-temperate, old-growth, conifer hardwood forest in the snowy region of Japan

To clarify the establishment pattern of Cryptomeria japonica seedlings, the demography of current-year seedlings was studied under various micro-environmental conditions for 2 years in a cool-temperate old-growth forest in the snowy region of Japan. In both years, more than 70% of seedlings that emerged died within a year, and differences in the survival rate of seedlings with respect to micro-environmental conditions were similar. While a number of seedlings survived at the sites on fallen logs and in mineral soil, almost no seedlings survived at the sites with either broad-leaved or coniferous litters at the end of the first growing season. The negative litter effect may kill most small seedlings of C. japonica. In addition, we found that survival rates of the seedlings were greater as the distance from the nearest adult and canopy openness increased. An analysis using Quantification Theory I showed that, of the possible micro-environmental factors, substrate conditions had the strongest effect on the survival of seedlings. The analysis also indicated that distance from the nearest adult and canopy openness also affected seedling survival significantly and to almost the same extent, although the effects were weaker than those for the substrate condition. Given the limited establishment sites for C. japonica seedlings, layering is suggested to be the main mode of regeneration in this forest.     

Field survival of containerized red and jack pine seedlings inoculated with mycelial slurries of ectomycorrhizal fungi

Red pine and jack pine seedlings growing in styroblocks were inoculated 8 wk after sowing with mycelium/agar slurries of 3 mycorrhizal fungi (Laccaria bicolor, Scleroderma citrinum, and an unidentified basidiomycete), and one suspected mycorrhizal fungus (Cantharellula umbonata). Seedlings inoculated with L. bicolor developed mycorrhizae earlier and in greater numbers than the other inoculation treatments, with red pine out-performing jack pine in both respects. At 34 wk following sowing, seedlings were outplanted on a cleared xeric site in Baraga Co., in Michigan's Upper Peninsula. Seedlings inoculated with C. umbonata failed to form mycorrhizae and were not outplanted. Inoculation treatments did not affect shoot or root weight at outplanting. Red pine inoculated with L. bicolor averaged 21% and 19% greater survival compared with control seedlings after one and two years in the field, respectively. Other inoculation treatments failed to increase seedling survival for either tree species. Jack pine demonstrated higher overall survival than did red pine for both years in all corresponding inoculation treatments.     

The effects of sulfometuron on the root growth of loblolly pine

The effect of sulfometuron (Oust) on the root growth of loblolly pine (Pinus taeda L.) seedlings was studied in the field and in two soil types in the greenhouse. In the greenhouse study sulfometuron was applied to the foliage only, the soil only, and to both foliage and soil at the rates of 0.10, 0.21, and 0.42 kg ai/ha. Twenty-eight days after application root growth significantly decreased for all methods of application and with increasing rates e.g., 0.10, 0.21, and 0.42 kg ai/ha sulfometuron reduced new root length by 42%, 53%, and 64%, respectively. Application in the field at the rate of 0.30 kg ai/ha resulted in a 68% reduction in root growth. However, by the end of the growing season treated seedling root and shoot biomass were 115% and 64% greater, respectively. To ensure earlier season survival the rate of sulfometuron applied should be kept at a minimum level that will allow both weed control and adequate root growth. Low rates would be particularly important during a dry planting season.     

Root and shoot allometry of bareroot and container Douglas-fir seedlings

Detailed root and shoot development of bareroot and container Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedling stocktypes were compared during the first growing season after outplanting. The study was installed in raised beds with ideal environmental conditions and at a field reforestation site. Survival at both sites was 98% and did not differ between stocktypes. Seedlings were excavated in spring (5, 8, 12, and 16 weeks after planting) and in fall (35, 40, and 45 weeks after planting). In spring, container seedlings had more numbers of new roots and greater new root and shoot biomass than bareroot seedlings at both sites. In fall, bareroot seedlings consistently averaged more new root growth (though nonsignificant) than container seedlings suggesting that stocktype differences may not continue long-term. Container seedlings had significantly greater water percent than bareroot seedlings at the field site (all sample dates) and the raised bed site (weeks 5, 8, and 40 only). Regardless of environmental conditions or season, seedlings at both sites maintained water percent between 60 and 70% of fresh weight. Seedlings grown in the raised beds had much greater growth than those grown in the field. However, relative growth patterns for the two stocktypes were very similar on each site. The data generated establish baseline differences between stocktypes for root initiation, growth, and allometry during the first year after planting. Challenges associated with root development research are discussed.