Agroforestry on alkali soils: Effect on some management practices on initial growth,biomass accumulation and chemical composition of selected tree species

This field study started in July 1982 on a typical alkali soil (Aquic Natrustalf, ESP 99.7) examined the growth responses to some management practices in a unified system planned to establish agroforestry. The planting of 3 salt tolerant tree species with two methods: on flat natural surface (FSPB) without rainwater conservation and on ridges (0.6 m high, 1.5 m at top and 2.5 m at base) having parallel trenches of the same section to store 300 mm of monsoon rainwater; constituted the main plot treatments. The tree planting with and without forage grassDiplachne fusca linn. in the inter-row space and planting in shallow (15 × 60 cm) and deep (15 × 180 cm to cross hard pan) augerholes filled with amendment treated soil (2 kg gypsum, 8 kg FYM, 50 g N, 10 g zinc sulphate and original soil) formed the sub and sub-plot treatments replicated 4 times in a split-split plot design.The mean plant height ofEucalyptus tereticornis smith;Acacia nilotica L; andParkinsonia aculeata L. in 2 years period was 273 and 328, 240 and 240 and 211 and 199 cm respectively with and without rainwater conservation. The corresponding height of the 3 tree species was 314 and 287, 250 and 231 and 207 and 203 cm with and without grass in the inter-row space. Similarly the plant height was 247 and 354, 182 and 298, 172 and 238 in shallow and deep augerholes respectively. The tree height and basal diameter differences with and without rainwater conservation and grass growth remained non-significant but deep augerhole planting was markedly superior to the shallow augerhole planting. The 2 year biomass accumulation also followed the same trend. The grass competed with trees for moisture during hot dry summer months and increased plant mortality particularly in the shallow augerholes and more so on ridges. The plant roots, essentially, remained confined to the amended soil of the augerholes in FSPB but proliferated in the loose soil of ridges or grass and submergence ameliorated surface soil of trenches.Acacia nilotica accumulated low sodium and had the lowest Na:Ca and Na:K ratio. It was found more promising than eucalyptus and parkinsonia as it experienced low mortality and had better chemical constitution to tolerate adverse alkali soil environment. The rainwater conservation system needed further evaluation before drawing final conclusions.     

Effect of site preparation techniques on Prosopis juliflora in an alkali soil

Effects of three methods of site preparation, i.e. trench (30 cm deep and 30 cm wide dug across the plots), pit (30 cm × 30 cm × 30 cm) and augerhole (15cm diameter and 90 cm deep) on raising Prosopis juliflora plantations on a highly alkali soil (pH₂ 10.3) were studied in a field experiment at Gudha Experimental Farm of the Central Soil Salinity Research Institute, Karnal. A uniform dose of gypsum of 3 kg per plant was mixed with the excavated soil before trenches/pits/augerholes were refilled and Prosopis planted. The study indicated that mean plant height and girth growth, recorded at 2 year intervals from planting up to 8 years, were greatest with the augerhole method. Similarly, the air dried shoot and root biomass accumulated by Prosopis in 6 years was maximum in augerhole planting. In trench and pit planting, most of the roots were confined to surface layers (0–60 cm), whereas in augerhole the roots were able to pierce the hard CaCO₃ layer (caliche bed) and were nearly 2.5 m deep 2 years after planting. Differential site preparation techniques showed little effect on N, P, K, Ca, Mg, S and Na concentrations in plant parts (leaf, branch and stem) of Prosopis both at 2 and 6 years after planting. Total removal of N, P, K, Ca, Mg and S through Prosopis parts at 2 and 6 years after planting was maximum in auger planting and minimum in trench planting. The augerhole was also superior to other techniques in pod production, litter yield and nutrient additions to the site. However, litter quality remained unaffected owing to planting techniques. In general, there was marked decrease in pH and electrical conductivity and appreciable improvement in organic carbon and available N status of the experimental soil owing to Prosopis growth, but effect of different site preparation methods was not significant. This study showed that site preparation for planting Prosopis in high pH soils in the vertically downward direction is more important than reclamation of surface soil in the horizontal direction.     

Forage production and quality of 4 perennial grasses grown under and outside canopies of matureProsopis glandulosa Torr. var.glandulosa (mesquite)

Comparisons were made of dry matter production and forage quality of two coolseason grasses, Canada wildrye (Elymus canadensis L.), Virginia wildrye (Elymus virginicus L.), and two warm-season grasses, green panic (Panicum maximum var.trichoglume Eyles) and plains bristlegrass (Setaria leucopila Scribn. & Merr.), planted under and outside the canopies of mature honey mesquite (Prosopis glandulosa Torr. var.glandulosa). Green panic gave the greatest cumulative dry matter yield in both canopy (5120 kg ha^–1) and open (3370 kg ha^–1) locations, followed by plains bristlegrass under mesquite (1130 kg ha^–1) and in the open (570 kg ha^–1). One-time yields from Canada wildrye and Virginia wildrye, under and outside mesquite canopy, were 247 and 329 kg ha^–1, and 272 and 268 kg ha^–1, respectively. Dry matter production of green panic (p=0.001) and plains bristlegrass (p=0.026) was greater under mesquite only for the first of four harvests, although both warm-season grasses exhibited a trend for greater production under mesquite than in the open. Average nitrogen content of green panic was greater (p=0.0004) under mesquite than in the open, while plains bristlegrass exhibited a trend for greater crude protein content in the open than under mesquite. Overall, moisture content of the warm-season grasses was greater (p=0.0001) under mesquite than in the open, while Virginia wildrye was more (p=0.002) succulent under mesquite than in the open. Averagein-vitro dry matter digestibility of warm-season grasses was almost significantly greater (p=0.0501) in the open than under mesquite. Canopy soils contained significantly more organic C (p=0.0004) and total N (p=0.0001) than open soils, with differences of 8.3 Mg organic C ha^–1 and 1.3 Mg total N ha^–1. Correlations indicated that soil fertility was more limiting to grass production than light intensity.     

An evaluation of agriculture, forestry and agroforestry practices in a moderately alkali soil in northwestern India

Productivity, sustainability and economics of agriculture, forestry and agroforestry land use practices were compared over a six year period in a split plot experiment on a moderately alkali soil of the Central Soil Salinity Research Institute, Karnal, India. Three commercial trees of the area formed the main plot treatments and four crop sequences were the sub-plots. The trees were: poplar (Populus deltoides), Acacia (Acacia nilotica) and Eucalyptus (Eucalyptus tereticornis), and the crop sequences were (1) rice (Oryza sativa)-wheat (Triticum aestivum) for four years followed by guinea grass (Panicum maximum)-oats (Avena sativa) for two years; (2) rice-Berseem (Trifolium alexandrium) for four years followed by cowpea (Vigna unquiculata)-Berseem for two years; (3) pigeonpea (Cajanus cajan)/sorghum (Sorghum bicolor)-mustard (Brassica juncea) for three years followed by turmeric (Curcuma longa) for three years and (4) no intercrops (only trees). Eucalyptus and poplar gained maximum height, girth and woody biomass in six years when they were intercropped with rice crops in sequences 1 and 2. Acacia attained maximum growth in the absence of intercrops. Protein content in guinea grass was more under tree canopies than in the open. Soil amelioration during five years followed the order: Acacia based system > poplar > Eucalyptus > sole crops. The benefit-cost ratio was heighest (2.88) in poplar based system and minimum (1.86) in Acacia based system. The study indicated that growing trees and agricultural crops together is a better land use option in terms of productivity, maintenance of soil conditions and economics. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of silicon-rich soil amendments on growth,mortality and bark feeding damage of Sitka spruce (Picea sitchensis) seedlings under field conditions

Alternative methods of protection are required against feeding by the large pine weevil (Hylobius abietis) on the bark of conifer seedlings. Silicon (Si) has been shown to enhance the resistance of plants to insect herbivores. This study investigated the effects of low doses of Si-rich soil amendments on growth, mortality and bark feeding damage of Sitka spruce (Picea sitchensis) seedlings. Two-year old seedlings were grown, individually, in soil taken from a tree nursery treated with coal ash, peat ash, rice husk ash, slag, sodium metasilicate or a commercially available Si fertiliser (Pro-Tekt) and planted out on two reforestation sites in Ireland. Seedlings grew well (about 20% growth in terms of height, 66% in root collar diameter, after two growing seasons), and Si-rich amendments did not have a significant effect on growth or mortality. Bark feeding damage on Si-treated seedlings did not vary significantly from control seedlings. Bark Si concentrations were not significantly larger in treated seedlings than in control seedlings, but control seedlings already had comparatively high bark Si concentrations (560?mg?kg^?1 dry tissue). In conclusion, Sitka spruce seedlings grown in the presence of Si-rich soil amendments prior to planting did not show greater resistance to weevil feeding under the present conditions.     

Productivity of alley farming with leucaena (Leucaena leucocephala Lam. de Wit) and Napier grass (Pennisetum purpureum K. Schum) in coastal lowland Kenya

Inadequate supply of fodder is a serious constraint to the potentially-promising small-holder-dairy production system in coastal Kenya. Alley farming could be an approach to addressing this problem. A study of forage production based on Napier grass and leucaena in an alley cropping system was conducted on an infertile sandy soil in lowland coastal Kenya. The effects of leucaena hedgerows,Clitoria ternatea (L.) intercropping, addition of slurry (110 t ha^–1 yr^–1) and two harvesting managements (severe and lenient) on the yield of Napier grass fodder, were assessed. The study was initiated in 1989 and three years results are reported.Napier grass fodder yields did not decline in the presence of leucaena heggerows in most harvests. Generally, the Napier rows adjacent to the hedgerows gave greater yields than in either the centre or sole Napier rows. Interplanting clitoria between Napier rows had a beneficial effect on Napier yields in the later harvests. Compared with sole Napier, the hedgerow treatment receiving slurry increased yield ha^–1 of Napier by 50%, of total forage by 80%, and of nitrogen (measured over two harvests) by 200%.During the first two years of cropping most treatments did not affect the OM and nitrogen content of the soil but by the end of the third cropping year, slurry application increased soil OM by 21% and slurry and clitoria treatments each increased soil nitrogen by 33%.The study demonstrated the increases in the supply and quality of forages for dairy cattle that can be achieved by planting complementary forages, legume and grass species in an intercropping system like alley farming and the benefits to soil composition by the return of slurry.     

Agroforestry for soil and water conservation in the western Himalayan Valley Region of India 1. Runoff, soil and nutrient losses

Erosion losses were investigated in a field experiment, from 90 × 15 m erosion plots at 4% slope in the western Himalayan valley region of India. The plots were planted with Leucaena leucocephala and Eucalyptus hybrid, either as block plantation or in alley farming with maize (Zea mays), Chrysopogon fulvus grass or turmeric (Curcuma longa). The treatments also included contour planting of sole maize, sole Chrysopogon fulvus grass and a clean weeded cultivated fallow. During the nine year study period, the average annual monsoon rainfall was about 1000 mm and it caused 347 mm runoff and 39 Mg ha^-1 soil loss per year from fallow plots. The runoff and soil loss were reduced by 27% and 45% by contour cultivation of maize. Contour tree-rows or leucaena hedges reduced the runoff and soil loss by 40% and 48%, respectively, over the maize plot, reducing soil loss to about 12.5 Mg ha^-1. This reduction in erosion was primarily due to the barrier effect of tree or hedgerows and micro-terraces formed through sediment deposition along the contour barriers. Such vegetative measures, that are productive while being protective, offer viable alternative for erosion control in areas with gentile slopes of the valley region. High density block plantations of eucalyptus and leucaena almost completely controlled erosional losses and can be recommended for steeper slopes that are vulnerable to heavy erosion. This revised version was published online in June 2006 with corrections to the Cover Date.     

浙江海宁鼠尾山露采废弃矿山植被修复的群落结构和持水效应研究

采用客土喷播、植生袋围堰造坑植树和基质型容器苗种植等技术对浙江海宁鼠尾山露采废弃矿山进行植被修复,3 a后形成乔木盖度31％、灌木盖度52％、草本盖度59％的森林植物群落,物种多样性较丰富,与周边山体自然植被的相似度为0.127 6.地上部分灌木和草本的生物干质量为657.16 g·m-2,地下部分生物干质量为254.82 g·m-2,枯落物干质量148.82 g·m-2.地上灌草植被和枯落物及土壤三者合计的蓄持水量为15.5 kg·m-22.研究结果为矿山生态环境治理的生态效益评价提供了基础数据和科学依据.     

Field performance of Scots pine (Pinus sylvestris L.) seedlings planted in disc trenched or mounded sites over an extended planting season

Economic pressures have driven an ever-widening period during which foresters use machines to plant Scots pine (Pinus sylvestris L.) seedlings. In Fennoscandia, this period has recently stretched to the entire growing season. To evaluate the performance of seedlings planted during this extended period, three experiments were carried out in Central and Northern Finland over 2 years. One-year-old and current-year seedlings were planted in mounds or disc-trenched furrows when soil temperatures were >0°C. When 1-year-old seedlings grown for spring planting and overwintered outdoors were planted after mid-June, more needles browned and growth was reduced, possibly because seedlings were oversized with respect to planting density and the volume of growth media. When current-year seedlings sown in spring were planted from July to November, those planted in late September and October grew less in later years than those planted earlier, but survival was unaffected. No large differences in field performance were found with respect to whether seedlings were planted in mounds or disc-trenched furrows. In conclusion, Scots pine seedlings can be machine planted in mounds or furrows during May and early June (later in the North) and then continued from early August until late September, provided climatic conditions in late spring and early autumn are typical and similar to those experienced in Central Finland.     

坡地种葛控制土壤水土流失技术研究

为探索坡地水土保持技术,以传统习惯种植作物为对照,开展了坡地种葛对减少水土流失技术的研究。结果表明:种植葛根可以有效地减少坡地土壤的地表径流量和土壤侵蚀量,种葛4年后地表径流量比对照减少一半以上;随着种葛年限的增加,土壤侵蚀量逐年降低。种葛第2年后,雨水对坡地土壤的侵蚀量比对照减少了58.0%,到第10年种葛处理的土壤侵蚀量比对照减少了91.1%。本研究通过对坡度在28°以内的坡地种葛,对减轻水土流失,改善土壤理化性状,培肥地力提供了一条新的有效技术途径。     

Silvicultural treatments for sapling mesquite (Prosopis glandulosa var. glandulosa) to optimize timber production and minimize seedling encroachment

To maximize lumber production and minimize weed problems with Prosopis glandulosa, silvicultural treatment methods were evaluated nine years after initiation. A randomized complete block design was used with four replicates and six treatments. Plots were shredder-harvested leaving sixteen 2-m squares on 10-m spacing that included a final rotation crop tree. In three of the treatments the crop trees were pruned to a single stem. To prevent re-establishment of mesquite in the interstitial areas, plots were spot sprayed with herbicides, disked, or disked and seeded with rye grass in 1986. Herbicide treatments and disking continued yearly through 1989. In 1991, disk treatments were repeated. After both 2.5 and 9 yrs, significant treatment differences were found for growth of basal diameter, growth of basal area, and growth of dry weight. The greatest crop tree growth occurred in treatments that were pruned with interstitial competition suppressed. Mortality was greatest in the dense treatments, while re-establishment of mesquite was greatest in the more open treatments. The greatest basal diameter growth of 1.21 cm year⁻¹ in the disked and pruned treatments is comparable to other fine hardwoods in temperate and dry tropical forests.     

永州新田石漠化坡地生态修复技术探究

在永州新田县梘头镇石漠化程度比较严重的两个村子,选定总计20 km 2石灰岩裸露坡地作为试验区域,运用基质覆盖和客土等方式进行土壤改良。试验区种植以棱角山矾为主体,混栽金钱柳,山核桃,黄花槐,白三叶,紫花苜蓿等乔灌木和植被的植物群落,种植周期为3年。期间,对不同覆盖和客土方式的试验区的主要种植树种的生长状态及对应的土壤理化特性进行检测及分析。结果表明,在永州石漠化地区的生态修复中,通过基质覆盖和客土可以改变土壤的pH值,增加土壤孔隙度,减少土壤容重,提高土壤肥力,促进植物生长,提高生态修复的效率。采用白三叶、紫花苜蓿植被覆盖具有采用基质覆盖的相近效能。利用当地的茅草与环保基质的混合覆盖,能有效地改善土壤容重,增强植物的抗旱水平。     

Assessing water use and soil water balance of planted native tree species under strong water limitations in Northern Chile

Some forest plantations with native species are established in semiarid central Chile to compensate for industrial activities such as those of mining. Two of those operational forest plantations were monitored from age 1 to 3 years-old (2014–2016). Some plant attributes and soil volumetric water content (VWC) were monitored for eight native tree species (Acacia caven, Schinus polygamus, Porlieria chilensis, Lithraea caustica, Quillaja saponaria, Cryptocarya alba, Drimys winteri and Maytenus boaria), and a water balance model fitted to assess plant water use. Site preparation comprised planting holes of 40 cm?×?40 cm by 50 cm in depth dug with a backhoe. Substrate was removed and mixed with compost in proportion 70:30 before mixing it in the planting hole. Planting holes acted as water reservoirs over the study period with soil VWC generally increasing with soil depth being also less variable deeper than in the upper soil layers. The ratio of adaxial (upper leaf side) to abaxial (lower leaf side) stomatal conductance approximately followed a species gradient from xeric to mesic. Irrigation represented about 26% and 53% of the total water input for the sclerophyll and the D. winteri plantation, respectively. At the plant level (0.4?×?0.4 m), soil evaporation and transpiration of D. winteri (273 and 232 mm year^?1, equivalent to 43.7 and 37.1 L plant^?1, respectively) were about twofold the values for the sclerophyllous/malacophyllous plantation (138 and 128 mm year^?1, 22.1 and 20.5 L plant^?1, respectively). We suggest the water budget for the sclerophyll/malacophyllous plantation was tight but feasible to be adjusted while for D. winteri irrigation was excessive, could be drastically reduced, and suppressed altogether if planted in gullies. We believe water balance models and soil moisture content sensors could be used to better plan and manage irrigation frequency and amounts in compensation forest plantations in semiarid central Chile.     

Nursery fertilization enhances survival and physiological status in Canary Island pine (<Emphasis Type="Italic">Pinus canariensis</Emphasis>) seedlings planted in a semiarid environment

We tested the hypothesis that fertilized containerized Pinus canariensis seedlings increases survival when planted in semiarid sites through the improvement of their physiological status during the establishment phase by an increment in root growth. Seedlings were cultured under two different regimes: traditional (in non-fertilized natural soil) and alternative (in fertilized peat). Morphological attributes and nitrogen content were measured before planting. Measurements of survival and growth in the plantation were made periodically for 2 years and physiological plant responses (leaf water potential, gas exchange and chlorophyll fluorescence) during the third summer after planting were tested and finally a set of plants were excavated to measure the same parameters as before planting. Seedlings cultivated using fertilized peat achieved the highest values for all of evaluated parameters. During the third dry season, big seedlings exhibited better physiological status. Therefore, enhanced root growth can result in better water uptake during the dry period thereby increasing survival and growth in the next few years after planting. A feed-back physiological model is proposed to explain P. canariensis establishment in a semiarid environment.     

Short-term impacts of soil amendments on belowground C cycling and soil nutrition in two contrasting Pinus taeda L. genotypes

We monitored two Pinus taeda L. genotypes, planted in 170 L lysimeters, subjected to different combinations of fertilization and logging residue (LR) incorporation for 1 year. The objectives were to elucidate how soil amendments modified soil biological properties and belowground C cycling, and secondly, to determine if planting of contrasting genotypes have a detectable impact on total soil CO₂ efflux (F_S). LR incorporation resulted in decreased bulk density, increased total soil porosity, and increased total soil C and N contained within the fine-soil fraction. For most of the experiment we found no consistent differences between genotypes; however, on the final two sampling dates a pattern emerged of one clone showing greater F_S. If this pattern continues or becomes stronger with increased occupation of soil by roots it may have an influence on total site net C exchange. Increased C loss by way of F_S and soil leaching made up approximately 7% of total C incorporated as LR. Conservative estimates using a constant rate of decomposition showed that it would take a minimum of 15 years to fully decompose the incorporated LR. Our data suggest that moderate rates of LR incorporation following harvesting over multiple rotations could increase SOM without negatively impacting plant growth, which could increase soil C sequestration.     

Effects of forest floor planting and stock type on growth and root emergence of Pinus contorta seedlings in a cold northern cutblock

A two-year field trial was conducted to determine the growth response, and root emergence pattern of interior lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) seedlings in response to container type and forest floor removal. Seedlings were grown in Styroblocks^TM, Copperblocks^TM, or AirBlocks^TM, and were planted directly into the undisturbed forest floor or into manually prepared planting spots where the forest floor had been scraped away to expose the mineral soil. Seedlings planted into scalped planting spots exhibited marginally but significantly (7%) greater above-ground growth rates (seedling stem volume); whereas seedlings planted into the forest floor produced significantly more (11%) new roots. There were no differences in above- or below-ground biomass. Seedlings grown in Copperblock^TM containers produced a higher proportion of roots near the top of the plug when tested at lifting, however this pattern was not observed in the field. Given that scalping is more costly than forest floor planting, and that the increased shoot growth was relatively small, we recommend that forest floor planting be considered as an alternative to manual spot scalping for sites, such as the site tested here: those with cold, but well-drained soils and where competition from other plants is not a serious problem.     

Testing fertilizer, gypsum, planting season and varieties of wild leek (Allium tricoccum) in forest farming system

Wild leek (Allium tricoccum) is an edible spring ephemeral of the eastern deciduous forests of North America that takes advantage of the short period of high light conditions between snowmelt and canopy closure to accumulate the carbon required to complete its annual growth and seed production. In Québec (Canada), this slow-growing species has been subjected to great harvesting pressure, which forced the provincial government to ban commercial harvest and sales in 1995. An illegal market has since developed and the plant is still under threat. Conservation of existing natural populations might be possible through commercial production of wild leek. To investigate this possibility, we set up plots in four sugar maple forest stands where different organic fertilizer and gypsum (0 or 3,000 kg ha^?1) applications were tested, together with two wild leek varieties, and bulb planting season. The two varieties, tricoccum and burdickii, despite morphological differences, are both suitable for cultivation. Planting bulbs in the spring seems more advantageous than in autumn, but these results will need to be confirmed. Fertilized plants exhibited better growth the year following transplantation than did non-fertilized plants. Belowground:aboveground biomass ratios indicated that plants receiving more fertilizer produced larger bulbs, but leaf size did not differ statistically. According to leaf nutrient analysis, fertilizers would need to be applied each year, whereas gypsum (as a calcium source) can be applied less frequently. Our results indicated a high potential for wild leek as a forest crop, at least when the bulbs are planted.     

重度盐碱地恢复羊草植被种植方法的试验研究

利用羊草种子和植株在吉林省中西部重度盐碱地上,进行不同种植方法重建或恢复以羊草为优势种的草原植被生态系统的试验研究。结果表明：羊草植株穴植第三年的保存率、盖度、平均高生长,分别是羊草植株缝植的1.40倍1、.30倍和1.60倍,分别是播种羊草的2.40倍、2.90倍和4.20倍,差异极显著;穴植羊草植株在pH值10.0~10.9的土壤上的成活率分别是缝植羊草、播种羊草的1.08倍和9.80倍;播种羊草在积水较多、积水时间15 d时就会全部死亡,穴植和缝植羊草的成活率也只有20%~30%;用穴植法栽植羊草植株,3 a即可形成稳定的羊草群落。     

Agroforestry in the Bolivian Altiplano: evaluation of tree species and greenhouse growth of wheat on soils treated with tree leaves

Severe environmental problems encountered in the highlands of Bolivia may be remedied through the adoption of agroforestry systems, never before studied adequately in this region. As a first step, seven tree species were tested for growth, survival and health at two elevations in the Bolivian altiplano. Species responded variably with Buddleja coriacea Remy., Pinus radiata D. Don. and Eucalyptus globulus Labill. (at the higher elevation) and E. globulus, Baccharis spp., Robinia pseudoacacia L. and B. coriacea (at the lower elevation), displaying high survival, growth and health. In a related greenhouse study, grain yields of wheat planted in soils amended with incorporated foliage of B. coriacea, P. radiata and E. globulus increased three-fold (0.3 g·plant⁻¹ to >1.0 g·plant⁻¹) over grain yields in unamended soils (B. coriacea > P. radiata = E. globulus). Grain nitrogen (mg·plant⁻¹) increased equally in soils amended with P. radiata and B. coriacea foliage (18 mg N⋅plant⁻¹ to 20 mg·plant⁻¹) but decreased in soils amended with foliage of E. globulus (18 g·plant⁻¹ to 9 g·plant⁻¹). This revised version was published online in June 2006 with corrections to the Cover Date.     

Induced competition among scots pine seedlings and its effect on future timber quality

Height and diameter increment and timber quality in Scots pine (Pinus sylvestris L.) planted as seedlings of different sizes were studied in two experiments. When compared 32–37 years after planting, seedlings that were smaller than neighbouring seedlings at the time of planting, had generally attained lower height and diameter, and had higher mortality compared to seedlings that were of equal size or larger than their neighbours. Tree size was strongly related to seedling size two years after planting. Trees originating from small seedlings had thinner annual rings and branches than trees originating from large seedlings. These characters are of importance for timber quality. It seems that the competitive ability of a tree is to a large extent established early in stand development.