Effects of Seedbed Density on One-Year-Old <Emphasis Type="Italic">Fraxinus angustifolia</Emphasis> Seedling Characteristics and Outplanting Performance

To assess the effects of seedling spacing on one-year-old seedling morphology in the nursery, seeds of three provenances of Fraxinus angustifolia were sown at five different seedling spacings within rows of two different spacings in the seedbed. Subsequent growth performance of one-year-old seedlings was assessed by planting in the forest. Within row spacings were: 4.3, 5.0, 6.3, 8.3, and 12.5 cm, and there were five rows at 20 cm apart, or three rows at 33 cm apart across the 1.2 m wide seedbeds. Both spacings within and between rows significantly affected shoot height, root collar diameter, root dry weight and shoot dry weight, but not root/shoot ratio. Wider spacings produced larger seedlings, but only the wider spacing within rows significantly increased fine and coarse root mass. Provenances showed significant differences in diameter, root/shoot ratio, and fine and coarse roots, and they also showed interactions with row spacings in height and diameter measurements. One year after outplanting, diameter growth was significantly related to provenance, and diameter growth was 88% greater for trees from 33 cm nursery row spacing than those from 20 cm nursery row spacing.     

Short- and intermediate-term effects of site and plant preparation techniques on reforestation of a Mediterranean semiarid ecosystem with <Emphasis Type="Italic">Pinus halepensis</Emphasis> Mill

A 5-year study of the reforestation of a semiarid Mediterranean ecosystem with Pinus halepensis is presented. Reforestation of Mediterranean semiarid ecosystems is challenging as a result of harsh environmental conditions and historical human exploitation leading to degradation. New techniques have to be developed in order to increase survivorship and growth that integrates nursery and field treatments. A total of 60 treatments resulting from 12 site × 5 plant preparation techniques were tested. Plant preparation consists of mycorrhizing in nursery, extra fertilizing in nursery, planting in containers in the nursery, planting in the field with a polypropylene tube, and control plants (bred in plastic bags). Soil preparation consists of hole, subsoiling without amendment, subsoiling with composted organic amendment added in the surface or in the furrow of plantation and subsoiling with fresh organic amendment added in the surface or in the furrow of plantation. Each one of these treatments was tested with a hydrophilic acrylic copolymer and without it. Survivorship was very high (0.91) given the prevailing environmental conditions. Subsoiling promoted higher survival than holes, and plants bred in containers had lower levels of survivorship than control ones. Protecting seedlings with polypropylene tubes had no effect on survivorship. The most effective treatment for promoting growth was organic amendment, the effect of which increased until the fourth year. Protection with tubes was very effective in increasing height, although only in the short-term. Subsoiling also promoted faster growth than holes, although the effect was less noticeable after 3 years and was, in any case, less effective than organic amendment. Other treatments promoting faster growth were the use of fresh organic waste as opposed to composted waste and its incorporation in the plantation furrow rather than as a layer on the surface. The addition of hydrophilic acrylic copolymer reduced growth during the first months of the reforestation. The fertilization of plants in the nursery and inoculation with spores of mycorhyzal fungi did not improve seedling growth. Plants bred in containers performed worse than control plants bred in individual plastic bags. The findings suggests the importance of nutrient supply in semiarid environments, an aspect that has been previously neglected in favor of water supply. Organic amendments reinforce both and can be recommended as long as adequate environmental controls are in place.     

栽植密度对黄檗苗期生物量的影响

以黄檗3 a生幼树为材料,对不同栽植密度的生物量进行研究,结果表明:栽植当年和翌年秋季的成活率与保存率分别为92%和91%。不同株距树高、地径生长量均达到极显著差异(P0.01),树高、地径生长量从大到小顺序依次为株距0.5 m1 m0.3 m1.5 m;而不同行距对树高、地径生长量均无影响。采用一元生物量模型计算生物量,总生物量最大的种植密度为33 300株·hm~(-2)(株行距0.3 m×1.0 m),可产生干物质3 930.06 kg·hm~(-2);最小的为3 300株·hm~(-2)(株行距1.5 m×2.0 m),干物质仅为344.08 kg·hm~(-2)。     

Loblolly and slash pine height and diameter are related to soil drainage in winter on poorly drained silt loams

Soil drainage characteristics in winter and the heights and diameters of 10-year-old loblolly and slash pines (Pinus taeda L. and P. elliottii Engelm. var. elliottii) were measured on three poorly-drained silt loam sites that had been bedded, furrowed, or disked before planting. Quadratic response functions were used to determine the relationship between depth to water table or volume of drained soil in winter and mean tree height or diameter. These quadratic response functions (species × height or diameter: drainage characteristics) showed that diameter and height were significantly related to soil drainage in winter on these silt loams soils. Slash pines grew better than loblolly pines under more poorly drained conditions while loblolly pines grew better under the better drained conditions. On unbedded silt loams, the soil drainage in winter needed to maximize tree height was 42 cm for loblolly and 49 cm for slash pine. Pines planted on beds did not generally grow better than those on flat-disked plots because where bedding would be most benefical the practice did not form enough additional drainage to significantly influence pine development.     

Soil loss and run-off in young forest stands as affected by site preparation technique: a study in NE Portugal

Soil loss rates currently recorded in forests are very low. Nevertheless, that may not be the case during stand installation and early tree growth stage, when soil is disturbed and scarcely covered. Site preparation techniques, performed to improve soil conditions for plant growth, should help reducing this erosion potential. In this study, several site preparation techniques were applied prior to installing a mixed stand (Pseudotsuga mensiezii and Castanea sativa) and a subsequent monitoring scheme of run-off and soil loss ran for 2?years in order to compare their effectiveness for erosion control. The experimental area, near Macedo de Cavaleiros, NE Portugal, at 700?m elevation, with annual means of 656?mm rainfall and 12°C temperature, has Mediterranean climatic conditions. Experimental design comprised three blocks, corresponding to different topographical positions (near flat plateau, moderate slope shoulder and steep mid-slope), where eight treatments were randomly distributed in plots with 375?m² area: (1) Original soil control (no intervention on the original abandoned field); (2) No subsoiling, no ploughing, plantation with hole digger; (3) Subsoiling over the whole area, with covering shovel; (4) No subsoiling, contour bunds shaped by two plough passes; (5) Subsoiling in future plantation rows, contour bunds shaped by two plough passes; (6) Subsoiling over the whole area, contour bunds shaped by two plough passes; (7) Subsoiling over the whole area, contour ploughing over the whole area; and (8) Potential erosion (subsoiling over the whole area, ploughing downhill). Sediment and water exported from small plots (2.5?m² average area), two replicates per treatment and block, were collected after each rainfall erosion event, in a total of 21, summing 1,876-mm precipitation in 2?years. Mean annual run-off and soil loss in the original soil were 3.4?mm and 11.6?g?m^?2, respectively. In treatments 2–7, values were higher 3–7 times, for run-off, and 5–12 times, for soil loss. Potential erosion averages 2.3 t ha^?1 year^?1. Soil loss and run-off tend to increase with tillage intensity associated with site preparation technique, even though average two-year losses, in all cases, are below tolerable rates. Soil loss and run-off rates decreased with time, becoming globally negligible after 2?years. Slight and moderate soil disturbance intensity site preparation techniques reduce erosion rates to 30% of potential erosion, halving the critical period when above tolerance rates may occur.     

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.     

Comparison of minirhizotron and soil core methods for quantifying root biomass in a temperate alley cropping system

A study was carried out in southern Indiana, USA with the objective of comparing soil core sampling and the minirhizotron technique in quantifying fine root biomass and root distribution patterns in an alley cropping system with black walnut (Juglans nigra L.), northern red oak (Quercus rubra L.) and maize (Zea mays L.). Spatial variation in tree rooting pattern was investigated prior to planting maize. Tree fine root biomass was quantified at distances of 0, 1.1, 2.3, 3.5, and 4.3 m where 0 m represents the tree row and 4.3 m represents the middle of the alley. Root samples were collected to a depth of 90 cm using a hydraulic auger. Maize rooting pattern was determined 65 days after planting to the same depth. Using plexiglass access tubes installed near the actual soil core locations and a minirhizotron camera root images were recorded on a VHS tape. These images were later analyzed using a raster based GIS software (ERDAS-IMAGINE). Regression analysis revealed significant relationships between root surface area measurements from minirhizotron observations and fine root biomass data from soil coring for all species. Predicted fine root biomass data were also in close agreement with actual fine root biomass for all species examined. Maize root biomass was slightly, but not significantly, underestimated by the minirhizotron technique in the top 30 cm soil layer. No significant underestimation or overestimation of root biomass in surface or deeper soil layers was observed for the tree species. The results indicate that minirhizotron can be used in quantifying fine root biomass if site and species specific predictive models can be developed. This revised version was published online in June 2006 with corrections to the Cover Date.     

不同土壤埋藏深度下山杏(Prunus srmeniaca)种子的萌发和幼苗发育

A semi-greenhouse study was conducted to understand the effects of soil burial depth on seed germination and seedling development. The seeds of wild apricot (Prunus armeniaca) were buried at the soil depths of 0-cm, 4-cm, 8-cm, and 12-cm, respectively, to simulate the seed hoarding behavior of rodents in the field. The results revealed that the rates of seed germination and established seedlings from buried seeds were both the highest in 4-cm burial depth group, and then decreased with increasing soil depth. The number of rotten seeds increased in deeper burial depth. It is unfavourable for seed germination at 0-cm burial depth (i.e., seeds were laid on soil surface). There was insignificant effect of burial depth on growth of established seedlings. The results from this study indicated that proper burial depth in soil would be helpful for the seed germination and seedling growth. The seedlings derived from buried seeds at shallower depth (4 cm) in this research have advantage in their early development.     

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。     

Competition for water in a pecan (Carya illinoensis K. Koch) – cotton (Gossypium hirsutum L.) alley cropping system in the southern United States

Understanding the belowground interactions between trees and crops is critical to successful management of agroforestry systems. In a study of competition for water in an alley cropping system consisting of pecan (Carya illinoensis) and cotton (Gossypium hirsutum) in a sandy loam soil (Rhodic Paleudult) in Jay, Florida, root systems of the two species were separated by trenching to 120 cm depth. A polyethylene barrier was installed in half of the plots. Spatial and temporal variations in soil water content, root distribution and water uptake by both species, and leaf area development and height of cotton were measured. Interspecific competition for water was greater in the non-barrier treatment near tree rows than at the alley center. Competition became evident 3 to 4 weeks after emergence of cotton and increased during the following 7 to 8 weeks. Compared with the non-barrier treatment, the barrier treatment had higher soil water content and better growth of cotton (height, leaf area, and fine root biomass). Cotton lint yield in the barrier treatment (677 kg ha^–1) was similar to that in a sole-crop stand, but higher than in the non-barrier (502 kg ha^–1) treatment. Lint production efficiency of plants was higher in the interior rows in the non-barrier treatment (0.197 kg lint per square meter of leaf area, compared to 0.117 kg in the barrier treatment). The results suggest that trenching or even deep disking parallel to the tree row may reduce competition for water, but the impact on tree growth cannot be established from this study. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of different culture media on the growth of Indian sandalwood (Santalum album L.) seedlings in Zhanjiang, Guangdong, southern China

We studied the effects of different culture media on the growth of India sandalwood (Santalum album L.) seedlings in Zhanjiang, Guangdong Province in southern China. Five different growth substrates, lateritic subsoil, burnt soil, agricultural soil, peaty soil and coconut dust, were used as the basic culture materials and seven different treatments of composition were used as potting media. Kuhnia rosmarinifolia Vent. was used as a primary host plant for all treatments. Statistically significant differences were found between treatments in respects of survival rate (p < 0.001), height (p < 0.001), ground diameter (p < 0.001) and biomass (p = 0.002), as well as for quality index (p = 0.001) of S. album seedlings after 6-month growth in containers with different culture media. Among all treatments, the treatment combining burnt soil, peat and coconut dust in a weight ratio of 1:1:1 plus 2% calcium super-phosphate as basal manure achieved the best performance for most of the seedling growth parameters, including survival rate (98%), height (35.81 cm), ground diameter (0.56 cm), biomass (4.46 g) and quality index (0.65), followed by the treatment using only burnt soil plus 2% calcium super-phosphate as the culture medium (survival rate 86%, height 29.23 cm, ground diameter 0.48 cm, biomass 3.36 g and quality index 0.52), while the treatment using only lateritic subsoil plus the basal manure as the medium obtained the poorest results in survival rate (38%), height (12.04 cm), ground diameter (0.19 cm), biomass (0.26 g) and quality index (0.043). Increasing the proportion of lateritic subsoil in the medium when mixed with peat and coconut dust did not show statistically significant differences in survival, height, ground diameter, biomass nor in quality index. In consideration of cost, using burnt soil plus 2% calcium super-phosphate as basal manure may be the optimum culture medium for large-scale production of Indian sandalwood seedlings in Guangdong, southern China.     

Microbial community diversity in a 21-year-old temperate alley cropping system

Soil physical and chemical properties in the crop alleys and tree rows in alley cropping systems vary greatly due to differences in litter quality and microclimate under trees compared to the alleys. Variations in soil properties influence microbial diversity and function, and thus, in alley cropping systems, bacterial diversity could be different between soils in tree rows and crop alleys. The objective of this study was to compare and contrast soil bacterial diversity in the crop alleys and tree rows in a 21-year-old alley cropping system in Northeast Missouri, USA. Soil samples were taken in three parallel transects to a depth of 10 cm in the tree row and at the middle of the alley in a silver maple (Acer saccharinum) alley cropping system with a companion maize (Zea mays)—soybean (Glycine max) rotation. Soil bulk density, C and N concentrations were similar between the different transects while minor differences were observed between crop alleys and tree rows. No significant difference in bacterial diversity was observed between the tree rows and alley soil based the denaturing gradient gel electrophoresis profiles, band richness (19.6 and 22.8 for tree row and alley, respectively) and Shannon–Weiner diversity (2.958 and 3.099 for tree row and alley, respectively). Identification of bacterial genera revealed dominance of gram +ve as well as gram ?ve bacteria in both soil types. Ordination plot revealed no clustering effect based on location (transect) or on the cropping system in the different samples. Bacterial diversity in crop alleys most likely was influenced not only by the maize-soybean rotation, but also by the tree rows contributing both above and belowground litter for the past 21 years.     

Okra production with pine straw mulch

Conventional planted okra in Booneville, Arkansas and Lorman, Mississippi were mulched with loblolly pine straw (Pinus taeda L.) and longleaf pine straw (P. palustris Mill.), respectively, at a rate of 11 t/ha or left bare. At Booneville, plant stand, season yields (18.6 t/ha), pod weight (16.3 g), plant dry weight (2.3 kg), or stem diameter (3.5 cm) were not affected by the loblolly pine mulch. However, mulch application increased pod number (1.22 vs. 1.06×10⁶/ha) and plant height (1.5 vs. 1.6 m), while reducing weed competition (0.05 vs. 0.40 t/ha) and visible plant stress, during periods of soil moisture deficits. Soil temperatures at 5 and 15 cm depth were reduced by mulch until mid-August when plant canopies covered the rows. Seasonal moisture at 30 and 45 cm depths was similar between mulched and bare soils, based upon unreplicated neutron probe measurements. At Lorman, season okra yield (29.8 vs. 24.6 t/ha), number of pods per ha (1.24 vs. 1.07×10⁶) and weed competition were reduced and soil pH lowered 0.56 units by longleaf pine straw mulch. Mulch reduced early season yield at both locations.     

珍稀树种南方红豆杉造林技术试验

通过试验研究不同造林株行距（A）、不同整地挖穴规格（B）对南方红豆杉人工造林成活率、幼林高度及地径生长量的影响差异,试验结果表明：2.0 m×2.5 m造林株行距（A）＋60 cm×50 cm×40 cm整地规格（B）最好,1年生幼林平均成活率达95.6%。     

不同栽培措施对马莲花成活率和生长量的影响

通过野生马连花引种和田间对比试验,研究了不同分株大小、栽植密度、栽植时期和栽植深度对马莲花成活率、分蘖增生、叶片生长和花茎分化的影响。结果表明:发芽前栽植、10芽分株和隐芽外露栽植有利于提高成活率,栽植密度(株距×行距)40cm×40cm栽植有利于分蘖增生、叶片生长和花茎分化。     

Performance of height-classified Eucalyptus camaldulensis seedlings after one year in the field

Eucalyptus camaldulensis seedlings of 16–25, 26–35, 36–45 and 46–55cm height classes were used to examine the effect of planting stock quality on field performance. Survival, height and diameter (10cm above ground) were assessed 6 and 12 months after planting out. Significant height differences (P 0.05) existed between the 16–25 and 46–55cm height classes at 6 months age. There were no significant (P 0.05) differences in all these parameters at 12 months after planting out throughout the four height classes. It is concluded that the height classification approach for E. camaldulensis seedlings has very little value if the seedlings are in the 16–55cm height range. Until other nursery stock grading approaches are studied, 16–25cm seedling height class is as effective as the taller ones and would therefore be more economical for dry zone afforestation in Malawi.     

不同造林因子对文冠果成活率及种子产量的影响

为了探讨适合北方地区文冠果造林的技术体系,特选择整地深度、栽植时间、栽植密度3个因子开展研究,比较了不同因子处理下文冠果的生长情况,结果表明:北方地区文冠果造林前整地深度以30 cm左右为佳,春季栽植的效果比秋季栽植好,适宜的株行距为2 m×2 m,结实量为16841个·hm^-2,种子产量为221.8 kg·hm^-2。     

Impacts of burial and insect infection on germination and seedling growth of acorns of Quercus variabilis

Rodents usually exert important role, through their scatter seed hoarding behavior, on plant regeneration in the field. To investigate the effects of burial and insects infection on germination and seedling growth of acorns of Quercus variabilis, perfect and infected acorns were buried in the soil among four depths, 0 cm, 4 cm, 8 cm and 12 cm, to simulate the seed hoarding behavior by rodents in the field. The results showed that (1) the germination rate were both high, under 4 cm burial depth, for perfect and infected acorns (92% and 53% separately), and decreased significantly with increased burial depth; (2) perfect acorns germinated better in 4 cm burial depth group by autumn of first year; (3) there 32% (perfect) and 26% (infected) acorns with 0 cm burial depth, on the soil surface, germinated successfully; for infected acorns, the 4 cm depth group had the best germination or seedling recruitment in both the first year and the second year; (4) acorns of Q. variabilis exhibited dormancy period ca 7 months; (5) burial, infection, and the interaction between these two factors influenced several aspects including stem height, leaf weight, Tannic acid, and biomass within seedling growth; (6) the results from this study suggest that proper burial would be helpful for the germination and seedling growth, and seedlings of shallow buried acorns had an advantage in their early development; and (7) infection by insects will not inevitably influence seedling early development.     

早春类短命植物猪牙花种球栽植试验初报

利用不同覆土深度对猪牙花种球进行栽植试验。试验结果表明:4种不同覆土深度下猪牙花种球栽植成活率不同,覆土深度为5、10、15、20cm时其成活率存在极显著差异;其中覆土深度为15cm时,成活率最高,为88%。     

南亚热带杉木人工成熟林密度对土壤养分效应研究

[目的]研究5种不同密度林分土壤剖面养分含量的变化规律。[方法]以广西大青山37年生杉木密度试验林为研究对象,测定了A(1 667株·hm-2)、B(3 333株·hm-2)、C(5 000株·hm-2)、D(6 667株·hm-2)、E(10 000株·hm-2)5种密度下0 100 cm土层土壤养分含量。利用单因素方差分析和多重比较判断不同密度和不同土层土壤养分含量的差异。[结果]表明:(1)杉木人工成熟林大多数土层土壤有机质、全氮、碱解氮、全磷、有效性铁含量在A、B等低密度林分中最高,并且在0 30 cm的土壤中,随密度的增加表现出总体下降的变化趋势,而土壤pH值与全钾、速效钾随密度的增加而上升,交换性钙与交换性镁含量受密度影响不明显;(2)土壤有机质、全氮、碱解氮、有效磷、速效钾、交换性钙、交换性镁和有效性铁含量均随土层深度的增加而明显下降,0 30 cm表层土壤的降幅较大,密度对不同土壤深度养分含量的变化具有一定影响。[结论]初植密度对杉木人工成熟林土壤养分含量影响明显,低初植密度更有利于杉木人工林土壤肥力的长期维持,南亚热带杉木林密度对土壤养分的影响深度可达60 cm。