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1
Yunusov, R., und M. Sattorova. „Productivity Of Intensive Varieties In Apple Trees Depends On Density Of Trees In Orchards“. American Journal of Agriculture and Biomedical Engineering 03, Nr. 05 (22.05.2021): 1–7. http://dx.doi.org/10.37547/tajabe/volume03issue05-01.
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In this article, the productivity of intensive apple varieties was studied, grafting on vegetatively propagated medium-sized stock MM - 106 Golden Delicious and Korey. In a long-term watering experience, it was revealed that in the optimal planting scheme of 6 × 4, the yield of apple fruits increased by 12-15%, the quality of apple fruits improved significantly.
2
Bobkov, Anton. „VC-density for trees“. Archive for Mathematical Logic 58, Nr. 5-6 (30.11.2018): 587–603. http://dx.doi.org/10.1007/s00153-018-0652-1.
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3
Shafii, Bahman, James A. Moore und James D. Newberry. „Individual-tree diameter growth models for quantifying within-stand response to nitrogen fertilization“. Canadian Journal of Forest Research 20, Nr. 8 (01.08.1990): 1149–55. http://dx.doi.org/10.1139/x90-153.
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Diameter-increment models for nitrogen-fertilized stands were developed using data from permanent research plots in northern Idaho. The equations partially resembled PROGNOSIS model diameter growth formulations. Results indicated that both initial tree size and initial stand density produced significant interactions with treatment to explain an individual tree's response to fertilization. Larger trees in a stand showed more fertilization response than smaller trees. Furthermore, individual trees in low-density stands showed more fertilization response than those growing in high-density stands. These diameter increment predictive equations were formulated to be compatible with individual-tree distance-independent simulation models.
4
Tomášková, I., R. Pokorný und V. Marek M. „Influence of stand density, thinning and elevated CO2 on stem wood density of spruce“. Journal of Forest Science 53, No. 9 (07.01.2008): 400–405. http://dx.doi.org/10.17221/2142-jfs.
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Stem wood density (SWD) of young Norway spruce trees (<i>Picea abie</I>s [L.] Karst.) growing at ambient (A variant, 350 µmol(CO<sub>2</sub>)/mol) and elevated (E variant, A + 350 µmol(CO<sub>2</sub>)/mol) atmospheric CO<sub>2</sub> concentration inside of the glass domes with adjustable windows was estimated after six and eight years of the cultivation. Stand density of two subvariants (s – sparse with ca 5,000 trees/ha and d – dense with ca 10,000 trees/ha) and thinning impact (intensity of 27%) on SWD and its variation along the stem vertical profile were investigated. After six years of CO<sub>2</sub> fumigation, stems of sparse subvariant had about 10% lower values of SWD comparing to dense ones, although the difference was not statistically significant. In 2004 (two years after thinning), the SWD values were higher in all subvariants along the whole stem vertical profile. This increase was more obvious in E variant (about 6% in d subvariant and only 3% in s subvariant). The highest increase of SWD values was found in Ed subvariant, particularly in the middle stem part (about 8%, statistically significant increase).
5
Kuo, Shu-Fu, und Yu-Shan Shih. „Variable selection for functional density trees“. Journal of Applied Statistics 39, Nr. 7 (Juli 2012): 1387–95. http://dx.doi.org/10.1080/02664763.2011.649717.
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6
Jim, C. Y. „Trees and high-density urban development“. Habitat International 17, Nr. 3 (Januar 1993): 13–29. http://dx.doi.org/10.1016/0197-3975(93)90014-4.
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7
Meyer, Daniel W. „Density estimation with distribution element trees“. Statistics and Computing 28, Nr. 3 (16.05.2017): 609–32. http://dx.doi.org/10.1007/s11222-017-9751-9.
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8
De Mil, Tom, Yegor Tarelkin, Stephan Hahn, Wannes Hubau, Victor Deklerck, Olivier Debeir, Joris Van Acker, Charles de Cannière, Hans Beeckman und Jan Van den Bulcke. „Wood Density Profiles and Their Corresponding Tissue Fractions in Tropical Angiosperm Trees“. Forests 9, Nr. 12 (07.12.2018): 763. http://dx.doi.org/10.3390/f9120763.
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Wood density profiles reveal a tree’s life strategy and growth. Density profiles are, however, rarely defined in terms of tissue fractions for wood of tropical angiosperm trees. Here, we aim at linking these fractions to corresponding density profiles of tropical trees from the Congo Basin. Cores of 8 tree species were scanned with X-ray Computed Tomography to calculate density profiles. Then, cores were sanded and the outermost 3 cm were used to semi-automatically measure vessel lumen, parenchyma and fibre fractions using the Weka segmentation tool in ImageJ. Fibre wall and lumen widths were measured using a newly developed semi-automated method. An assessment of density variation in function of growth ring boundary detection is done. A mixed regression model estimated the relative contribution of each trait to the density, with a species effect on slope and intercept of the regression. Position-dependent correlations were made between the fractions and the corresponding wood density profile. On average, density profile variation mostly reflects variations in fibre lumen and wall fractions, but these are species- and position-dependent: on some positions, parenchyma and vessels have a more pronounced effect on density. The model linking density to traits explains 92% of the variation, with 65% of the density profile variation attributed to the three measured traits. The remaining 27% is explained by species as a random effect. There is a clear variation between trees and within trees that have implications for interpreting density profiles in angiosperm trees: the exact driving anatomical fraction behind every density value will depend on the position within the core. The underlying function of density will thus vary accordingly.
9
Marini, Richard P., und Donald S. Sowers. „Peach Tree Growth, Yield, and Profitability as Influenced by Tree Form and Tree Density“. HortScience 35, Nr. 5 (August 2000): 837–42. http://dx.doi.org/10.21273/hortsci.35.5.837.
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`Norman' peach [Prunus persica (L.) Batsch] trees were trained to the central-leader or open-vase form and were planted at high (740 trees/ha), or low (370 trees/ha) density. A third density treatment was a HIGH → LOW density, where alternate trees in high-density plots were removed after 6 years to produce a low-density treatment. From 3 to 5 years after planting, trunk cross-sectional areas (TCA) increased most for low-density trees. After 9 years, TCA was greatest for low-density and least for high-density trees. Because of differences in tree training, central-leader trees were taller than open-vase trees and tree spread was greater for low-density than for high-density trees. Annual yield per hectare was 15% to 40% greater for high-density treatments than for low-density treatments, but tree form had little influence on yield. Average fruit weight tended to be greater for low-density than for high-density treatments, but cumulative marketable yield was greatest for high-density and lowest for HIGH → LOW treatments. Income minus costs for 9 years was nearly $4200/ha higher, and net present value was about $2200/ha higher, for open-vase than for central-leader trees (P = 0.08). Cumulative net present value for the 9 years was about $2660/ha higher for high-than for low-density trees (P = 0.36).
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Marini, Richard P. „618 Tree Form and Tree Density Affect Peach Tree Cropping and Profitability“. HortScience 34, Nr. 3 (Juni 1999): 554B—554. http://dx.doi.org/10.21273/hortsci.34.3.554b.
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`Norman' peach trees were trained to the central-leader or open-vase form and were planted at high (740 trees/ha) or low (370 trees/ha) density. A third density treatment was a high/low density, where alternate trees in high-density plots were removed after 6 years to produce a low-density treatment. Annual yield per hectare was ≈15% to 40% greater for high-density treatments than for low-density treatments, but tree form had little influence on yield. Fruit size tended to be greater for low-density than for high-density treatments, but cumulative marketable yield was greatest for high-density and lowest for high/low density treatments. After 9 years, cumulative crop value was higher for open-vase than central-leader treatments (P = 0.12), but tree density had less of an effect on crop value (P = 0.21). Cumulative costs were highest for high-density treatments, but were not influenced by tree form. Income minus costs was nearly $4500/ha higher for open-vase than for central-leader trees and net present value was more than $2000/ha higher for high-density than low-density trees (P = 0.20). Open-vase trees were more profitable than central leader trees and should be planted at densities of about 700 trees/ha in the mid-Atlantic region.
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Wertz, Bogdan, Mariusz Bembenek, Zbigniew Karaszewski, Wojciech Ochał, Maciej Skorupski, Paweł Strzeliński, Andrzej Węgiel und Piotr S. Mederski. „Impact of Stand Density and Tree Social Status on Aboveground Biomass Allocation of Scots Pine Pinus sylvestris L.“ Forests 11, Nr. 7 (17.07.2020): 765. http://dx.doi.org/10.3390/f11070765.
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Stand density changes due to aging and thinning interventions. At the same time, the social status of trees develops and varies due to different genetic conditions as well as access to nutrients and light. Trees growing in diverse conditions gain their social status in the stand, which, in the end, influences their development and biomass allocation. The objective of this research was to discover if stand density or tree social status has an impact on a tree’s aboveground biomass allocation. The study was carried out in five premature and five mature pine stands, growing in the same soil conditions. The selected sample stands had a different growing density, from low to high. In each sample stand, 10 trees were selected to represent a different social status, according to the Schädelin classification. There were 100 trees felled in total (50 in the premature stands and 50 in the mature stands), for which the dry biomass of the stem, living and dead branches, needles, and cones was determined. The results showed that stand density only had an impact on the branches’ biomass fraction but not the stem and foliage fractions, while social status had an impact on all the fractions. Dominant and codominant trees, as well as those with developed crowns, had a smaller share of the stem and higher share of branches in comparison with trees of a lower social status.
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Natali, S., C. Xiloyannis und M. Mugano. „WATER CONSUMPTION IN HIGH DENSITY PEACH TREES.“ Acta Horticulturae, Nr. 173 (Dezember 1985): 413–20. http://dx.doi.org/10.17660/actahortic.1985.173.47.
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13
Brown, Helen, Katrina Proust, Barry Newell, Jeffery Spickett, Tony Capon und Lisa Bartholomew. „Cool Communities—Urban Density, Trees, and Health“. International Journal of Environmental Research and Public Health 15, Nr. 7 (22.07.2018): 1547. http://dx.doi.org/10.3390/ijerph15071547.
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A move towards more compact and climate-resilient cities is being encouraged around the world. As part of these plans, there is a need to manage the potential conflict between increasing urban densities and the extent of tree canopy in cities. Reductions in tree canopy are a major contributor to the urban heat island (UHI) effect, which will act to reduce rather than increase climate resilience in many cities. A systems thinking approach called Collaborative Conceptual Modelling was used to study the interaction between urban infill, tree canopy, and human health in Perth, Australia. The results indicated that under current planning policies and development practices, the behaviour of the system is dominated by the drive towards higher housing densities. While this may result in the attainment of urban infill targets, it is likely to lead to a reduction in tree canopy, higher temperatures, and a decrease in a range of other benefits provided by trees. Recommended actions to overcome this behaviour were determined by the identification of leverage points in the system. These included a shift to a sustainable development paradigm that places greater value on the environmental and social benefits provided by trees and a greater emphasis on a climate-resilient future. Market and legislative mechanisms should be integrated into the city’s greening strategy and development plans to ensure the protection of existing trees and the inclusion of new trees on public and private land.
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Ooi, Hong. „Density Visualization and Mode Hunting Using Trees“. Journal of Computational and Graphical Statistics 11, Nr. 2 (Juni 2002): 328–47. http://dx.doi.org/10.1198/106186002760180545.
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15
Zheng, Zheng, Shubin Zhang, Guoping Yang, Yong Tang, Jerry Baskin, Carol Baskin und Lianyan Yang. „Abundance and distribution of cavity trees in an old-growth subtropical montane evergreen broad-leaved forest“. Canadian Journal of Forest Research 39, Nr. 11 (November 2009): 2234–45. http://dx.doi.org/10.1139/x09-149.
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We examined the relationship between the density of cavity trees and forest structure characteristics and explored the occurrence of cavity trees among different tree species and diameter breast height (DBH) size in a subtropical evergreen broad-leaved forest in the Ailao Mountains in southwestern China. Cavity trees accounted for 7.9% of living trees and 16.3% of dead trees. Average density of living cavity trees (86.3 trees·ha–1) was 6.9 times that of dead cavity trees. Density of living cavity trees was positively correlated with the density of living trees. Cavity trees showed a skewed distribution among DBH classes that peaked at DBHs of 20–40 cm. Moreover, the probability that a living tree was cavity-bearing was logistically related to DBH. Overall, the likelihood of trees being cavity-bearing differed significantly among species. The proportions of cavity trees among the 23 species having more than 63 trees were positively related to the average DBH and to the largest DBH recorded for each species. We suggest that (1) living tree density is important in determining density of cavity trees and (2) differences in proportion of living cavity trees among species is caused mostly by differences in average DBH of each species.
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Outcalt, Kenneth W. „Stand Density Affects Growth of Choctawhatchee Sand Pine“. Southern Journal of Applied Forestry 10, Nr. 3 (01.08.1986): 128–31. http://dx.doi.org/10.1093/sjaf/10.3.128.
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Abstract Choctawhatchee sand pine (Pinus clausa var. immuginata D. B. Ward) was grown for 20 years at densities of 400, 600, and 800 trees per acre. Growing Choctawhatchee sand pine at 400 trees per acre resulted in significantly larger trees, but less wood was produced per acre than at higher densities. The ideal density depends on the management objectives, but for rotations of 20-25 years and chip harvesting systems, a density of 600 trees is recommended. For rotations of 30-35 years with conventional bolt and log harvests, 400 to 500 trees per acre seems better. South. J. Appl. For. 10:128-31, Aug. 1986.
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Mijatović, Aleksandar. „Spectral properties of trinomial trees“. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 463, Nr. 2083 (10.04.2007): 1681–96. http://dx.doi.org/10.1098/rspa.2007.1845.
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In this paper, we prove that the probability kernel of a random walk on a trinomial tree converges to the density of a Brownian motion with drift at the rate O ( h 4 ), where h is the distance between the nodes of the tree. We also show that this convergence estimate is optimal in which the density of the random walk cannot converge at a faster rate. The proof is based on an application of spectral theory to the transition density of the random walk. This yields an integral representation of the discrete probability kernel that allows us to determine the convergence rate.
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Piispanen, Riikka, Jaakko Heinonen, Sauli Valkonen, Harri Mäkinen, Sven-Olof Lundqvist und Pekka Saranpää. „Wood density of Norway spruce in uneven-aged stands“. Canadian Journal of Forest Research 44, Nr. 2 (Februar 2014): 136–44. http://dx.doi.org/10.1139/cjfr-2013-0201.
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This study focused on wood density and annual ring width in Norway spruce (Picea abies (L.) Karst.) grown in uneven-aged stands (UAS). In total, 96 trees were harvested from five UAS that had been managed by single-tree selection for decades. A data set of 27 trees from even-aged stands (EAS) was used for comparison. In the UAS trees, high density and narrow annual rings were found in the juvenile wood near the pith. Thereafter, wood density rapidly decreased until the 20th annual ring, followed by an increase toward the bark. In the outermost rings, wood density again slightly decreased. The trends in wood density in the UAS trees correspond with those reported for naturally regenerated, even-aged Norway spruce stands, with the exception of the decrease in the outermost rings. A mixed linear model with ring width, cambial age, and canopy position as fixed parameters accounted for 53% of the variation in wood density of the UAS trees. In contrast to UAS trees, EAS trees showed increased wood density in the outer rings as a result of decreasing growth rate. The abrupt change in wood density of UAS trees may affect the properties of timber sawn close to the pith.
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Ishikawa, Yoshiharu, Kunio Mizuhara und Shinnya Ashida. „Effect of Density of Trees on Drag Exerted on Trees in River Channels“. Journal of Forest Research 5, Nr. 4 (November 2000): 271–79. http://dx.doi.org/10.1007/bf02767121.
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20
Hamido, Said A., und Kelly T. Morgan. „Effect of Various Irrigation Rates on Growth and Root Development of Young Citrus Trees in High-Density Planting“. Plants 9, Nr. 11 (29.10.2020): 1462. http://dx.doi.org/10.3390/plants9111462.
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Citrus yields have declined by almost 56% since Huanglongbing (HLB) was first found in Florida (2005). That reduction forced citrus growers to replant trees at much higher densities to counter-balance tree loss. The current project aims to determine how much water is required to grow citrus trees at higher planting densities without reducing their productivity. The study was initiated in November 2017 on eight-month-old sweet orange (Citrus sinensis) trees grafted on the ‘US-897′ (Cleopatra mandarin × Flying Dragon trifoliate orange) citrus rootstock planted in the University of Florida, Southwest Florida Research and Education Center (SWFREC) demonstration grove, in Immokalee, FL (lat. 26.42° N, long. 81.42° W). The soil in the grove is Immokalee fine sand (Sandy, siliceous, hyperthermic Arenic Alaquods). The demonstration grove included three densities on two rows of beds (447, 598, and 745 trees per ha) replicated four times each and three densities of three rows of beds (512, 717, 897 trees per ha) replicated six times. Each density treatment was irrigated at one of two irrigation rates (62% or 100%) during the first 15 months (2017–2019) then adjusted (2019–2020) to represent 26.5, 40.5, 53, and 81% based on recommended young citrus trees evapotranspiration (ETc). Tree growth measurements including trunk diameter, height, canopy volume, leaf area, and root development were evaluated. During the first year, reducing the irrigation rate from 100% to 62% ETc did not significantly reduce the young citrus tree growth. Conversely, the lower irrigation rate (62% ETc) had increased citrus tree’s leaf area, canopy volume and tree heights, root lifespan, and root length by 4, 9, 1, 2, and 24% compared with the higher irrigation rate (100%), respectively. Furthermore, the root lifespan was promoted by increasing planting density. For instance, the average root lifespan increased by 12% when planting density increased from 447 to 897 trees per ha, indicating that planting young trees much closer to each other enhanced the root’s longevity. However, when treatments were adjusted from April 2019 through June 2020, results changed. Increasing the irrigation rate from 26.5% to 81% ETc significantly enhanced the young citrus tree growth by increasing citrus tree’s canopy volume (four fold), tree heights (29%), root lifespan (86%), and root length (two fold), respectively. Thus, the application of 81% ETc irrigation rate in commercial citrus groves is more efficient for trees from two to four years of age.
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Jakubowski, Marcin, und Marek Dobroczyński. „Allocation of Wood Density in European Oak (Quercus robur L.) Trees Grown under a Canopy of Scots Pine“. Forests 12, Nr. 6 (30.05.2021): 712. http://dx.doi.org/10.3390/f12060712.
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The allocation of wood density in trees depends on many factors, but mainly on the tree species. A great number of studies have analysed wood density in dominant or codominant trees, but only a few have focused on trees grown under canopy. We examined the basic wood density and fresh wood density of natural origin oaks growing under canopy of artificially planted Scots pine. The major purpose of the work was to study the wood density allocation in different parts of the trees such as the trunk and branches. From a total of 80 oaks we selected eight model trees and measured biometric features of their trunks and crowns. Wood samples from different parts of the trunk and crown were collected after the trees were felled. We observed significant differences between the average basic wood density (595 kg·m−3) and the average fresh wood density (1031 kg·m−3). The central part of the trunk and heartwood shows much higher density than the outer part of the trunk and sapwood, which corresponds to the model of ring-porous trees. Both types of wood density (basic and fresh) were also higher in the trunk than in the branches. The wood density of the branches differed between two zones: A1, which was closer to the trunk and had higher density; and A2, which was farther away from the trunk with lower density. Wood density shows positive correlation with crown length but not with crown width, which was more connected with diameter at breast height. We found lower value of slenderness than the value reported by other authors in oaks planted without canopy. The allocation of wood density in trees is associated with the potential mechanical load.
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Djomo, Adrien N., Guylene Ngoukwa, Louis Zapfack und Cedric D. Chimi. „Variation of Wood Density in Tropical Rainforest Trees“. Journal of Forests 4, Nr. 2 (2017): 16–26. http://dx.doi.org/10.18488/journal.101.2017.42.16.26.
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Klemelä, Jussi. „Visualization of Multivariate Density Estimates With Shape Trees“. Journal of Computational and Graphical Statistics 15, Nr. 2 (Juni 2006): 372–97. http://dx.doi.org/10.1198/106186006x113007.
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Gwaze, David, und Anthony Elliott. „Cavity Trees, Snags, and Overstory Density in a Riparian Forest in Northeastern Missouri“. Northern Journal of Applied Forestry 28, Nr. 2 (01.06.2011): 105–9. http://dx.doi.org/10.1093/njaf/28.2.105.
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Abstract Snags and cavity trees are important for wildlife habitat, yet knowledge about their abundance and effects of forest management on these components is lacking for riparian forests. We evaluated the effects of clearcutting with reserves, basal area retention, and no harvest on snags and cavity trees in a riparian forest in northeastern Missouri. We also determined whether the established guidelines for snags and cavity trees in Missouri are being met. Preharvest results indicated that 11.3% of standing trees were snags, and 7% of live standing trees were cavity trees at this site. The proportion of snags was greater in small-diameter trees; however, the proportion of live trees with cavities increased as dbh increased. Preharvest snag density (20.6 trees/ac) and cavity trees (21.2 trees/ac) were well above the current minimum recommendations for wildlife tree retention on bottomland forests in Missouri. Following the harvest and girdling of residual trees >8 in. dbh, the abundance of snags increased, whereas cavity tree densities decreased. If the bottomland hardwood forest is going to contribute habitat of cavity tree-using wildlife, greater attention is needed to retaining cavity trees when harvesting.
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Brown, Gerald R., und Dwight E. Wolfe. „Optimal Training of Apple Trees for High-density Plantings“. HortScience 35, Nr. 4 (Juli 2000): 555D—555c. http://dx.doi.org/10.21273/hortsci.35.4.555d.
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An experiment was initiated at the Univ. of Kentucky Research and Education orchard, Princeton, Ky., to determine the training practices needed to obtain early production and optimal fruit size from trees trained to either the slender spindle or the French axe system on vigorous sites. One-hundred-eighty trees (five rows, 32 trees per row) of `Golden Delicious' on M.9 rootstock were planted in May 1997, in a randomized complete-block design with eight treatment combinations, consisting of two training systems and four levels of training intensity. Trunk circumference averaged 61 cm at planting and did not vary significantly among rootstocks. A trellis was constructed, and trickle irrigation was installed. All trees are currently alive. Each season, over half the total time spent training the trees was spent during the first 5 weeks the trees were trained. About 2 minutes per week was needed to train each tree during the first 5 weeks, but only 45 seconds per week was needed in the sixth through the 16th week. Trunk circumference, yield, and average weight per fruit did not vary significantly in the analysis of variance. Training per kilogram of fruit averaged 4.2 minutes.
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Devyatov, A. S. „Fruiting of High-density Apple Orchards on Clonal Rootstocks“. HortScience 31, Nr. 4 (August 1996): 665e—665. http://dx.doi.org/10.21273/hortsci.31.4.665e.
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Orchard densities from 833 to 2500 trees/ha were studied on sod-podzolic soil (annual precipitation 550 mm). An orchard was planted in Spring 1990 and 1991 using 2-year-old nursery trees grown in film containers. The interval between trees in the row was 1 to 1.5 to 2 to 2.5 and 3 m. The trees were grafted on dwarf rootstock (62-396) and semi-dwarf (54-118). The commercial fruiting of `Tellisaare' began the third year after planting, `Antey' the fourth, and Spartan at fifth. The initial yield of `Antey in the most dense treatment was 14.5 t·ha–1, `Tellisaare' was 15 to 22 t·ha–1, according to rootstocks. Average yield of `Antey' on 62-396 for 1992–95 at the orchard density of 2500 trees/ha was 10 t·ha–1·year–1 and on rootstock of 54-118 it was 21 t·ha–1. However, yield of `Tellisaare' 54-118 for 1992–1995 was 13 to 15 t·ha–1 in all treatment of orchard density from 1666 to 833 trees/ha. The annual yield of this cultivar grafted on rootstock 54-118 at a tree density of 2500 plants/ha increased to 18.3 t·ha–1.
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Calderón-Cortés, Nancy, Luis H. Escalera-Vázquez und Ken Oyama. „Occurrence of termites (Isoptera) on living and standing dead trees in a tropical dry forest in Mexico“. PeerJ 6 (16.05.2018): e4731. http://dx.doi.org/10.7717/peerj.4731.
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Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60–98% of standing dead trees and 23–59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057–0.066 trees/m2) than in riparian forests (0.022 and 0.027 trees/m2), even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01–0.09 trees/m2) than in larger class sizes (0–0.02 trees/m2). Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil.
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Robinson, Terence L., Alison M. DeMarree und Stephen A. Hoying. „Economic Comparison of Five High-density Apple Planting Systems“. HortScience 40, Nr. 4 (Juli 2005): 1128A—1128. http://dx.doi.org/10.21273/hortsci.40.4.1128a.
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We performed an economic analysis of five orchard production systems [Slender Pyramid/M.26 (840 trees/ha), Vertical Axis/M.9 (1538 trees/ha), Slender Axis/M.9 (2244 trees/ha), Tall Spindle/M.9 (3312 trees/ha), and Super Spindle (5382 trees/ha)] using composite yield and labor usage data from several replicated research plots in New York state. Other costs and fruit returns were averages from a group of commercial fruit farms in New York state. The systems varied in costs of establishment from a low of $18,431/ha for the Slender Pyramid system to high of $47,524/ha for the Super Spindle system. The large differences in establishment costs were largely related to tree density. All of the systems had a positive internal rate of return (IRR) and net present value (NPV) after 20 years. They ranged from a low of 7.5% IRR for the Slender Pyramid system to a high of 11.1% IRR for the Slender Axis system. Profitability, as measured by NPV, was curvilinearly related to tree density with intermediate densities giving greater profitability than the highest densities. The optimum density was 2600 trees/ha when NPV was calculated per hectare, but only 2200 trees/ha when NPV was calculated per $10,000 invested. The earliest break-even year was 10 for the Slender Axis and Tall Spindle systems. The latest break-even year was 13 for the Slender Pyramid. An estimate of the number of hectares required to produce a $100,000 annual profit to the business was 222 for the slender pyramid system and 84–104 ha of the three best systems (Super Spindle, Tall Spindle, and Slender Axis). The analysis revealed that efforts to control establishment costs of land, trees and support system can substantially increase lifetime profits.
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Curtin, Patrick J., Benjamin O. Knapp, Steven B. Jack, Lance A. Vickers, David R. Larsen und James M. Guldin. „Effects of overstory competition on canopy recruitment patterns of naturally regenerated longleaf pine on two site types“. Canadian Journal of Forest Research 50, Nr. 7 (Juli 2020): 624–35. http://dx.doi.org/10.1139/cjfr-2019-0343.
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Recent interest in continuous cover forest management of longleaf pine (Pinus palustris Mill.) ecosystems raises questions of long-term sustainability because of uncertainty in rates of canopy recruitment of longleaf pine trees. We destructively sampled 130 naturally regenerated, midstory longleaf pines across an 11 300 ha, second-growth longleaf pine landscape in southwestern Georgia, United States, to reconstruct individual tree height growth patterns. We tested effects of stand density (using a competition index) and site quality (based on two site classifications: mesic and xeric) on height growth and demographics of midstory trees. We also compared height growth of paired midstory and overstory trees to infer stand regeneration and recruitment dynamics. In low-density stands, midstory trees were younger and grew at greater rates than trees within high-density stands. Midstory trees in low-density stands were mostly from a younger regeneration cohort than their paired overstory trees, whereas midstory–overstory pairs in high-density stands were mostly of the same cohort. Our results highlight the importance of releasing midstory longleaf pine trees from local competition for sustained height growth in partial-harvesting management systems. They also demonstrate patterns of long-term persistence in high-density stands, indicating flexibility in the canopy recruitment process of this shade-intolerant tree species.
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Walker, David R. „APPLE TREE DENSITY AS RELATED TO PRODUCTION AND ECONOMICS“. HortScience 27, Nr. 12 (Dezember 1992): 1263d—1263. http://dx.doi.org/10.21273/hortsci.27.12.1263d.
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Spur and nonspur `Red Delicious' apple trees on M.26, 7, 106, and 111 were planted at different spacings. Yields were recorded for 15 years to assess the effect of early production on the M.26 trees with the later production on the M.106 and M.111 trees. The field data have been used to calculate income and expenses on a hypothetical 16-ha orchard during the 15-year period.
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Skaria, Mani, und Zhang Tao. „309 Rapid Growth of Microbudded Citrus Planted Ultra-high Density“. HortScience 35, Nr. 3 (Juni 2000): 445C—445. http://dx.doi.org/10.21273/hortsci.35.3.445c.
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High-density or ultra-high-density orchards have had positive economic return up to 12 years after planting. However, an initial higher investment on more number of trees needed is a limiting factor for high-density planting. Our preliminary studies have shown that a microbudding technique that we had developed would produce less-expensive, budded citrus trees. In June 1997, several hundred microbudded citrus trees were planted in a field, under drip irrigation. The planting continued monthly until Dec. 1997. The cultivars planted were: `Marrs' orange, `Rio Red' grapefruit, `Meyer' and `Ponderosa' lemon, and satsuma mandarin. All plants were microbudded on sour orange rootstock grown in 5′′ long “conetainers.” Our objectives were to study the growth performance of small, microbudded trees planted in the field. The plants grew normally and even out-performed the conventionally budded trees in a field nursery next to the test plot. In Dec. 1999, tree height reached 60 inches. Five percent of the trees produced fruit and they were normal in shape, color, and quality.
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Ghimire, Tara Bahadur, und Om Prakash Singh Bana. „Soil Physico-Bio-Chemical Properties under Poplar + Indian Mustard Inter Cropping System“. Journal of Nepal Agricultural Research Council 1 (20.09.2016): 14–20. http://dx.doi.org/10.3126/jnarc.v1i0.15719.
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A field experiment was conducted during the winter seasons of 2008-10 at Agroforestry Research Centre, Pantnagar, India with aim to examine the effect of different levels of recommended Nitrogen (N): Phosphorus (P): Potassium (K) (NPK) on soil physico-bio-chemical properties under varying poplar tree densities with mustard introcropping. Lower soil bulk density was recorded under 1000 trees/ha density compared to sole crop in both the year. Soil bulk density (BD) decreased underneath trees. However, soil pH, available N and K were not influenced by tree density in both the years. Electrical conductivity (EC) and soil organic carbon (SOC) increased underneath trees of either tree density compared to sole crop in both the years. Significantly (P<0.05) higher available P was recorded under 1000 trees/ha density compared to 250 and 500 trees/ha densities including sole crop in 2008-09. Similarly, soil microbial biomass carbon (SMBC) increased with increasing the tree density and significantly (P<0.01) higher value was recorded under 1000 trees/ha density compared to sole crop and sparse density both the years except 2009-10, where 500 and 1000 trees/ha densities remain statistically at par. On the other hand, dehydrogenase activity (DA) was maximum under 500 trees/ha density compared to sole crop and 1000 trees/ha density in both the years. Among the fertility levels, the maximum SOC and available N were recorded with 75% compared to 50, 100 and 125% of recommended NPK in 2008-09, except available N with 100% of recommended NPK. But, available P was more with 100% of recommended NPK in 2008-09. Similarly, maximum SMBC were recorded with 75 % compared to higher doses of recommended NPK in both the years. Similarly, BD, EC, SOC, available N, P and K were recorded maximum and soil pH minimum in 0-15 cm soil layers compared deeper layers.Journal of Nepal Agricultural Research Council Vol.1 2015 pp.14-20
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Vleut, Ivar, Samuel Israel Levy-Tacher, Willem Frederik de Boer, Jorge Galindo-González und Neptalí Ramírez-Marcial. „Can a fast-growing early-successional tree (Ochroma pyramidale, Malvaceae) accelerate forest succession?“ Journal of Tropical Ecology 29, Nr. 2 (März 2013): 173–80. http://dx.doi.org/10.1017/s0266467413000126.
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Abstract:Species-specific traits of trees affect ecosystem dynamics, defining forest structure and understorey development. Ochroma pyramidale is a fast-growing tree species, with life-history traits that include low wood density, short-lived large leaves and a narrow open thin crown. We evaluated forest succession in O. pyramidale-dominated secondary forests, diverse secondary forests, both 10–15 y since abandonment, and rain forests by comparing height, density and basal area of all trees (> 5 cm dbh). Furthermore, we compared species richness of understorey trees and shrubs, and basal area and density of trees of early- and late-successional species (< 5 cm dbh) between forest types. We found that tree basal area (mean ± SD: 32 ± 0.9 m2 ha−1) and height (12.4 ± 1.8 m) of canopy trees were higher, and density (1450 ± 339 ha−1) lower in O. pyramidale forests than in diverse forests, and more similar to rain forest. Understorey shrub diversity and tree seedling density and diversity were lower in O. pyramidale forests than in diverse forests, but these forest types had a similar density of early- and late-successional trees. Canopy openness (> 15%) and leaf litter (> 10 cm) were both highest in O. pyramidale forests, which positively affected density of understorey trees and shrubs and negatively affected density of late-successional trees. In conclusion, O. pyramidale forests presented structural features similar to those of rain forest, but this constrained the establishment of understorey tree species, especially late-successional species, decreasing successional development.
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Farooq, Taimoor, Wenjing Wu, Mulualem Tigabu, Xiangqing Ma, Zongming He, Muhammad Rashid, Matoor Gilani und Pengfei Wu. „Growth, Biomass Production and Root Development of Chinese fir in Relation to Initial Planting Density“. Forests 10, Nr. 3 (07.03.2019): 236. http://dx.doi.org/10.3390/f10030236.
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Chinese fir (Cunninghamia lanceolata (Lamb) Hook) is a commercially valuable timber species that is widely planted in southern China and accounts for 6.1% of the global plantation forests. However, appropriate planting density that ensures high plantation productivity is largely unexplored in this species. The aim of the study was to examine tree growth, biomass production, and its allocation among different organs in relation to initial planting density, and to examine whether planting density has an impact on root development. Mortality, diameter at breast height and tree-height of all trees were determined and measured in wider (2.36 × 2.36 m), intermediate (1.83 × 1.83 m) and narrow (1.44 × 1.44 m) spacing with stand density of 1450 trees ha−1, 2460 trees ha−1 and 3950 trees ha−1, respectively. In each stand, three plots of 20 × 20 m at a distance of 500 m were delineated as the sampling unit. Biomass was determined by destructive sampling of trees in each stand and developing allometric equations. Root morphological traits and their spatial distribution were also determined by carefully excavating the root systems. The results showed an increase in diameter of trees with decreasing stand density while tree height was independent of stand density. Biomass production of individual trees was significantly (p < 0.05) less in high-density stand (32.35 ± 2.98 kg tree−1) compared to low-density stand (44.72 ± 4.96 kg tree−1) and intermediate-density stand (61.35 ± 4.78 kg tree−1) while stand biomass production differed significantly in the order of intermediate (67.63 ± 5.14 t ha−1) > high (57.08 ± 3.13 t ha−1) > low (27.39 ± 3.42 t ha−1) stand density. Both average root length and root volume were significantly (p < 0.05) lower in the high-density stand than stands with low and intermediate density. Analysis of spatial distribution of root systems revealed no overlap between roots of neighboring trees in the competition zone in low-density stand, a subtle overlap in the intermediate density stand and larger overlap in the high-density stand. It can be concluded that better growth and biomass production in intermediate density stand could be explained by better root structural development coupled with minimal competition with understory vegetation and between trees; thus intermediate stand density can be optimal for sustaining long-term productivity and may reduce the management cost in the early phase of the plantation.
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Brand, David G., und Steen Magnussen. „Asymmetric, two-sided competition in even-aged monocultures of red pine“. Canadian Journal of Forest Research 18, Nr. 7 (01.07.1988): 901–10. http://dx.doi.org/10.1139/x88-137.
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A framework for analysis of even-aged plant monocultures was developed and used to examine hypotheses on the process of competition, using data obtained from three independently established red pine (Pinusresinosa Ait.) stand-density experiments. Growth rate and relative production rate (a measure of tree vigour) were computed for the individual trees in stands of differing density at points in time when these stands had the same mean stem volume. Competition is shown to be both asymmetric (small trees lose vigour more rapidly than large trees as density increases) and two-sided (not only do larger trees affect smaller trees, but to some degree small trees also cause growth reduction in larger neighbours). Increasing density results in increased size inequality as smaller trees lose vigour and become suppressed. The asymmetric, two-sided competition process in red pine stands is considered ecologically inherent for a species adapted to existence in even-aged monocultures.
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Morgan, Kelly T., Smita Barkataky, Davie Kadyampakeni, Robert Ebel und Fritz Roka. „Effects of Short-term Drought Stress and Mechanical Harvesting on Sweet Orange Tree Health, Water Uptake, and Yield“. HortScience 49, Nr. 6 (Juni 2014): 835–42. http://dx.doi.org/10.21273/hortsci.49.6.835.
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One of the primary reasons for the slow adoption of mechanical harvesting by Florida citrus growers is the physical injuries associated with it, including loss of leaves, twigs, flowers, and young fruits, limb breakage, and injuries to the bark and root. However, it has been shown that well-managed trees are capable of tolerating defoliation, limb loss, and root and bark injury caused by mechanical harvesting. Irrigation management is one of the most crucial factors that influence citrus tree health. A multiple-year field study was conducted on ‘Valencia’ sweet orange trees in a commercial citrus grove near Immokalee, FL, to determine the effect of initial tree canopy density and short-term drought stress on tree health, water uptake, and productivity of mechanically harvested trees. Three blocks were based on canopy density and overall appearance and indicated as low, moderate, and high canopy density. The experiment was laid in a split-plot design with four replications of six-tree plots of hand-harvested or mechanically harvested trees, taking drought stress or full irrigation as main treatments. The experimental design was repeated with trees in each plot of one of the three canopy density categories. After harvest, each six-tree plot was split into two three-tree subplots, where one subplot was drought-stressed and the other was fully irrigated. Harvesting was conducted in the Spring of 2010, 2011, and 2012 with the same experimental design and data collection procedures. The effects of short-term drought on water use and stem water potential were masked by heavy rains in Spring 2010 and thus no differences in the irrigation treatments were observed. In 2011 and 2012, stem water potential was unaffected by harvesting method. Water use was unaffected by harvesting method across the 3 years. Drought stress significantly increased pull force required to remove fruit and stem water potential after harvest. Although mechanically harvested trees lost leaf mass, with no rain before harvest, results from Spring 2011 and 2012 indicated that short-term drought stress had no effect on citrus leaf area irrespective of harvest method. Drought stress significantly increased fruit detachment force in low and moderate density but not in high-density trees resulting in increased force required to remove fruit from trees with moderate- to low-density canopies. Yield increased from 2010 to 2011 for mechanically harvested trees compared with hand-harvested for low-canopy density trees by 17% and moderate-canopy density trees by 8%, whereas high-density plots indicated similar yield after mechanical harvesting. Comparatively, yield in 2012 decreased in the low and moderate densities compared with yield in 2011 but increased in the high density by 14% and 53% in hand- and machine-harvested trees, respectively. Despite finding 2- to 3-fold more debris in the mechanically harvested trees than the hand-harvested trees, yields and other measured parameters were unaffected suggesting that mechanical harvesting of citrus trees did not have an adverse effect on growth and production of well-watered citrus trees.
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Carrillo, Isabel, Sofía Valenzuela und Juan Pedro Elissetche. „Comparative evaluation of Eucalyptus globulus and E. nitens wood and fibre quality“. IAWA Journal 38, Nr. 1 (13.02.2017): 105–16. http://dx.doi.org/10.1163/22941932-20170160.
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An evaluation of 100 Eucalyptus globulus and 100 E. nitens trees (six years old) was made using the Pilodyn micro-drilling tool as an indicator of wood density. Thirty E. globulus and thirty E. nitens trees with high, medium and low density were selected and sampled with an increment borer at breast height for anatomical analysis using fibre tester equipment and the Resistograph device to generate detailed information about fibre biometry and anatomical wood properties of both species for hybrid development. Eucalyptus globulus trees had a basic wood density average of 478 kg/m3, while E. nitens had a density of 490 kg/m3. Both micro-drilling tools showed significant correlation coefficients with basic wood density. Correlation coefficients between basic wood density and Pilodyn values were negative, being -0.53 (p = 0.01) and -0.68 (p < 0.001) for E. globulus and E. nitens, respectively. For both species a positive correlation was observed between basic density and Resistograph mean amplitude; the correlation coefficient was 0.84 (p < 0.001) for E. globulus, and 0.85 (p < 0.001) for E. nitens. Eucalyptus nitens trees had a higher density and amplitude average and smaller Pilodyn values than E. globulus trees, while the latter had higher coarseness, fibre length and diameter at breast height than E. nitens trees. However, E. nitens showed larger differences between features of earlywood and latewood in a growth ring than E. globulus trees.
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Rull, Juan, und Ronald J. Prokopy. „Effect of apple-orchard structure on interception of Rhagoletis pomonella (Diptera: Tephritidae) flies by odor-baited traps“. Canadian Entomologist 133, Nr. 3 (Juni 2001): 355–63. http://dx.doi.org/10.4039/ent133355-3.
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AbstractWe released marked mature male flies of the apple maggot, Rhagoletis pomonella (Walsh), inside and outside of square blocks of apple trees, Malus domestica Borkh. (Rosaceae), to test the effect of orchard structure on the interception of flies by odor-baited red-sphere traps. The blocks were composed of large trees planted at low density, medium-sized trees planted at medium density, or small trees planted at high density. The experiment was carried out in six commercial apple orchards during summer in 1997 and 1998. Released flies moving into blocks were intercepted in large proportions by baited perimeter traps, thus preventing fly penetration into sphere-protected blocks. In 1997, proportions of intercepted flies were higher for traps in blocks of small and medium-sized trees than for traps in blocks of large trees. In 1998, a year with an unusually low fruit load, interception remained high, but there were no differences in proportions of flies intercepted by perimeter traps among blocks of trees of different sizes. Overall we conclude that the tendency of apple growers in Massachusetts to replace large trees planted at low density with small or medium-sized trees planted at high or medium density will not adversely affect behavioral control programs for apple maggot flies. In fact, this practice may enhance the effectiveness of these programs through increased interception of immigrant adults.
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Devyatov, A. S. „Apple Orchard as Twin-row Tree-belt on Dwarf and Semi-dwarf Rootstocks“. HortScience 32, Nr. 3 (Juni 1997): 473C—473. http://dx.doi.org/10.21273/hortsci.32.3.473c.
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Growth and fruiting of apple trees in twin-row tree-belts were studied during 5 years after planting the orchard. Distance between belts was 4 m, between rows in a belt was 1 m, between trees in row 3 or 1.5 m, giving tree densities of 1335 or 2670 trees/ha, respectively. Control was a single-row planting 4 × 3 or 4 × 1.5 m, producing densities of 833 or 1665 trees/ha. Trees were trained as hedgerow in treatments with a density of 1335 or 833 trees/ha. Each tree in a twin-row belt had a separate crown with narrow passage between trees. This passage was cut through every year. Fruiting of `Tellisaare' began at 2nd leaf, `Antey' at 3rd, and `Spartan' at 4th leaf after planting. Total yield for 3 years in the highest density treatment of single-row planting of `Antey' and `Tellisaare' was >50 t·ha–1 and in twin-row orchard construction from 36 to 57 t·ha–1, depending on orchard density. The two-fold increase in orchard density from 1335 to 2700 trees/ha raised yield of `Antey' by 58% and `Tellisaare' by 33%. Single-row treatment with a tree density of 1665/ha averaged 17.1–17.5 t·ha–1 without great expenditure on pruning of trees. The fruit quality was very high in all treatments.
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Haavik, Laurel J., Brett P. Hurley und Jeremy D. Allison. „Effect of Sirex noctilio (Hymenoptera: Siricidae) attack density on Pinus sylvestris (Pinaceae) survival“. Canadian Entomologist 151, Nr. 3 (15.03.2019): 340–44. http://dx.doi.org/10.4039/tce.2019.12.
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AbstractPopulation density is often a critical factor in colonisation of trees by bark and wood-boring insects and may determine whether an exotic species is likely to establish and spread. In a manipulative field study, we investigated whether density of the attacking population of an exotic invasive woodwasp, Sirex noctilio Fabricius (Hymenoptera: Siricidae), affected survival and time-to-death of a favoured host tree, Pinus sylvestris Linnaeus (Pinaceae). We introduced mating pairs of woodwasps to stressed P. sylvestris at either high (15 mating pairs, nine trees) or low (two mating pairs, nine trees) density. More trees died, and more quickly, when exposed to the high versus low density of S. noctilio (78% versus 33% of trees). In the high-density treatment, year of tree death was synonymous with production of a S. noctilio F1 cohort (one-year or two-year generation time); this pattern was not as consistent in the low-density treatment. Although sample size was limited, our results indicate that attack density affects S. noctilio colonisation of P. sylvestris.
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Pietrzyk, P. J., und R. C. Lindenbergh. „Detection of harvested trees in forests from repeated high density airborne laser scanning“. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-5 (28.05.2014): 275–80. http://dx.doi.org/10.5194/isprsannals-ii-5-275-2014.
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Identification of harvested and fallen trees is a prerequisite for the detection and measurement of changes in forests. This paper presents a three step approach to monitor harvested and fallen trees based on direct comparison of repeated high density airborne LIDAR data. In a first step differences between data sets are obtained from a point to point comparison, such that the data can be reduced to the deviating points only. Secondly, the resulting points are clustered into spatially connected regions using region growing. Finally, individual trees are extracted from the clusters by analysing their relative proximity and by analysing geometric properties of points in the clusters. Two data sets, acquired at a four year interval and covering a forest with mainly deciduous trees, are compared. First results show that most points relating to a change can be extracted and that clustering of these with region growing enables us to efficiently separate harvested and fallen trees from the remaining trees. Grouped harvested trees could not be separated using the region growing approach due to touching crowns. Segmentation of these using spectral clustering however identified individual regions well, but the results depend mainly on the pre-defined number of clusters. Crowns of grouped trees can be therefore separated if the number of trees is known.
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Scott, William, Rodney Meade, Richard Leon, David Hyink und Richard Miller. „Planting density and tree-size relations in coast Douglas-fir“. Canadian Journal of Forest Research 28, Nr. 1 (01.01.1998): 74–78. http://dx.doi.org/10.1139/x97-190.
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Test plantations were established in western Washington and Oregon to compare tree growth at six initial planting densities ranging from 300 to 2960 trees/ha (120 to 1200/acre). A size-density relation was visually apparent 3 to 4 years after planting. Inventory data from the oldest 11 trials (5 or 6 years after planting) showed that initial spacing strongly influenced early growth of coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii). Average height and diameter at breast height were progressively larger as planting density increased; at the widest spacing (lowest stand density), average height was 75% and average diameter at breast height was 67% of that at the closest spacing. We have no firm explanation for the early faster tree growth at close spacings. Trees planted at 2960 trees/ha (1200 trees/acre) attained breast height (1.3 m) 2 years earlier than trees planted at a density of 300/ha (120/acre). This finding has practical significance to current efforts to achieve early establishment of plantations.
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Yun, Seok Hwan, Chae Yeon Park, Eun Sub Kim und Dong Kun Lee. „A Multi-Layer Model for Transpiration of Urban Trees Considering Vertical Structure“. Forests 11, Nr. 11 (31.10.2020): 1164. http://dx.doi.org/10.3390/f11111164.
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As the intensity of the urban heat island effect increases, the cooling effect of urban trees has become important. Urban trees cool surfaces during the day via shading, increasing albedo and transpiration. Many studies are being conducted to calculate the transpiration rate; however, most approaches are not suitable for urban trees and oversimplify plant physiological processes. We propose a multi-layer model for the transpiration of urban trees, accounting for plant physiological processes and considering the vertical structure of trees and buildings. It has been expanded from an urban canopy model to accurately simulate the photosynthetically active radiation and leaf surface temperature. To evaluate how tree and surrounding building conditions affect transpiration, we simulated the transpiration of trees in different scenarios such as building height (i.e., 1H, 2H and 3H, H = 12 m), tree location (i.e., south tree and north tree in a E-W street), and vertical leaf area density (LAD) (i.e., constant density, high density with few layers, high density in middle layers, and high density in lower layers). The transpiration rate was estimated to be more sensitive to the building height and tree location than the LAD distribution. Transpiration-efficient trees differed depending on the surrounding condition and plant location. This model is a useful tool that provides guidelines on the planting of thermo-efficient trees depending on the structure or environment of the city.
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Yu, Q., S. E. McKeand, C. D. Nelson, B. Li, J. R. Sherrill und T. J. Mullin. „Differences in wood density and growth of fertilized and nonfertilized loblolly pine associated with a mutant gene, cad-n1“. Canadian Journal of Forest Research 35, Nr. 7 (01.07.2005): 1723–30. http://dx.doi.org/10.1139/x05-103.
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A rare mutant allele (cad-n1) of the cad gene in loblolly pine (Pinus taeda L.) causes a deficiency in the production of cinnamyl alcohol dehydrogenase (CAD). Effects associated with this allele were examined by comparing wood density and growth traits of cad-n1 heterozygous trees with those of wild-type trees in a 10-year-old open-pollinated family trial growing under two levels of fertilization in Scotland County, North Carolina. In all, 200 trees were sampled, with 100 trees for each fertilizer treatment. Wood density measurements were collected from wood cores at breast height using X-ray densitometry. We found that the substitution of a cad-n1 for a wild-type allele (Cad) was associated with a significant effect on wood density. The cad-n1 heterozygotes had a significantly higher wood density (+2.6%) compared with wild-type trees. The higher density was apparently due to the higher percentage of latewood in the heterozygotes. The fertilization effect was highly significant for both growth and wood density traits. This study indicates that the cad-n1 allele could be a valuable gene to the pulp and paper industry for the purpose of enhancing pulp yields by increasing wood density.
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Kim, Wol Soo, Kyong Ho Lim, Hyung Kee Lim und Byeong Sam Kim. „Super-density Planting and Lower Canopy using Hardwood Cuttings of `Sunaga Wase' Peaches“. HortScience 32, Nr. 3 (Juni 1997): 477E—477. http://dx.doi.org/10.21273/hortsci.32.3.477e.
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In order to investigate the super-density planting in peach orchards, the experiment was carried out using nursery trees out of hardwood cuttings in `Sunaga Wase' peach (Prunus persica L.). The nursery trees were planted with various planting densities of 1 × 0.5 m (20,000 trees/ha), 1 × 1 m (10,000 trees/ha), 2 × 0.5 m (10,000 trees/ha), 2 × 1 m (5,000 trees/ha), and 6 × 5 m (330 trees/ha) as traditional density on 22 Mar. 1995. As soon as fruit harvest in mid-July, the peach trees were pruned by thinning and heading-back the shoots to induce the new shoot as well as to limit the tree height and lower the canopy. During the second year after planting, nursery cutting trees yielded the most peach fruits from the planting density of 1 × 0.5 m, as much as 14.37 t, which was 14 times higher than the 6 × 5 m of traditional density, followed by 2 × 0.5 m, 1 × 1 m, 2 × 1 m, and 6 × 5 m, respectively. According to summer pruning just after harvest, remaining vegetative buds burst and then the new shoot grew very vigorously in several days. The floral bud differentiation on the new shoots was lower, as much as 32.2%, than that of 77.9% in no-pruning shoots. There were no differences in fruit characteristics among various planting densities.
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Freckleton, Robert P., und Owen T. Lewis. „Pathogens, density dependence and the coexistence of tropical trees“. Proceedings of the Royal Society B: Biological Sciences 273, Nr. 1604 (16.08.2006): 2909–16. http://dx.doi.org/10.1098/rspb.2006.3660.
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There is increasing interest in the role played by density-dependent mortality from natural enemies, particularly plant pathogens, in promoting the coexistence and diversity of tropical trees. Here, we review four issues in the analysis of pathogen-induced density dependence that have been overlooked or inadequately addressed. First, the methodology for detecting density dependence must be robust to potential biases. Observational studies, in particular, require a careful analysis to avoid biases generated by measurement error, and existing studies could be criticized on these grounds. Experimental studies manipulating plant density and pathogen incidence will often be preferable, or should be run in parallel. Second, the form of density dependence is not well understood and, in particular, there are no data indicating whether pathogens cause compensating or overcompensating density responses. Owing to this, we argue that the potential for pathogen-induced density dependence to generate diversity-enhancing outcomes, such as the Janzen–Connell effect, remains uncertain, as coexistence is far more probable if density dependence is overcompensating. Third, there have been few studies examining the relative importance of intra- or interspecific density dependence resulting from pathogens (or, more widely, natural enemies). This is essentially equivalent to asking to what extent pathogens are host-specific. If pathogens are generalists, then mortality rates will respond to overall plant density, irrespective of plant species identity. This will weaken the intraspecific density dependence and reduce the diversity-promoting effects of pathogens. Finally, we highlight the need for studies that integrate observations and experiments on pathogens and density dependence into the whole life cycle of trees, because as yet it is not possible to be certain of the degree to which pathogens contribute to observed dynamics.
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Nilsson, Josefin A., Grace Jones, Charlotta Håkansson, Åsa Blom und Johan Bergh. „Effects of Fertilization on Wood Formation in Naturally Regenerated Juvenile Silver Birch in a Norway Spruce Stand in South Sweden“. Forests 12, Nr. 4 (30.03.2021): 415. http://dx.doi.org/10.3390/f12040415.
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This study investigates wood density and anatomy of juvenile silver birch stems in Sweden, grown in mixed conifer stands. Our aim is to investigate if fertilization provides increased growth, as well as an eventual reduction in stem wood density. Measurements of basic density, ring width, cell wall thickness, and vessels are analyzed for 20 birch trees. Bark to pith radial sections are analyzed using a light microscope and the freeware ImageJ to compare treatments and ages. The results show that trees with fertilizer treatment have wider growth rings and thinner cell wall thickness compared to unfertilized trees. The fertilized trees also have a lower cambium age at the same height and the same diameter, and a slightly lower stem mean density (420 kg m−3) than the unfertilized stems (460 kg m−3). Fertilizer is a significant determinant of density and cell wall thickness in nonlinear models. The fertilized trees have increased growth and reached a fixed diameter earlier. The age difference between the trees likely explains some of the differences in cell wall thickness. This study supports the use of fertilizer as a silvicultural option for increasing the growth rate of silver birch for a relatively small reduction of wood density.
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Salo, Ville. „Trees in Positive Entropy Subshifts“. Axioms 10, Nr. 2 (29.04.2021): 77. http://dx.doi.org/10.3390/axioms10020077.
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I give a simple proof for the fact that positive entropy subshifts contain infinite binary trees where branching happens synchronously in each branch, and that the branching times form a set with positive lower asymptotic density.
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Kuliešis, Andrius, Marius Aleinikovas, Edgaras Linkevičius, Andrius Kuliešis, Jonas Saladis, Mindaugas Škėma, Benas Šilinskas und Lina Beniušienė. „The Impact of Strip Roads on the Productivity of Spruce Plantations“. Forests 9, Nr. 10 (13.10.2018): 640. http://dx.doi.org/10.3390/f9100640.
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Strip roads serve to enable silviculture operations, maintain biodiversity, and decrease damages to the soil and environment. At the same time, strip roads decrease the productive area. The aim of this study is to evaluate the influence of strip roads on the productivity of spruce plantations growing in different density regimes. Five trials, each of 0.234 ha area, with different density regimes and two replications in an experimental spruce plantation were used for this study. The permanent plots were established in the plantation of 15 years of age and were remeasured every 4–5 years over 24 years. Differences in tree growth between outer rows bordering strip roads and inner rows, 1.75 and 3.5 m from the strip road, were estimated using t statistics. The gross annual increment of trees in outer rows at age 39 years exceeded the increment of trees in inner rows by up to 60%–78%. Increase of productivity occurred primarily due to the more intensive diameter growth and higher density of trees in the outer rows. In general, the influence of strip roads on the total productivity of plantation depends on the ratio of the growth intensity of trees between outer and inner rows as well as ratio of the width of treed strips to the width of the strip road.
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Lappi, Juha. „Plot size related measurement error bias in tree growth models“. Canadian Journal of Forest Research 35, Nr. 5 (01.05.2005): 1031–40. http://dx.doi.org/10.1139/x05-019.
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Local tree density around a tree affects tree growth because neighboring trees compete for the same resources. In forestry trees are often sampled by measuring all the trees in sample plots. The total number of the trees in a sample plot or in a larger plot that also encompasses a border zone is often used as the density measurement for all trees in the plot. When the plot density is used as the measurement of local density around a sample tree, the measurement error is correlated both with the measured value and with the true value. Thus none of the standard measurement error assumptions hold. The bias in the estimated density effect is related to the plot size. Assuming random tree locations and a simple linear model including both overall stand density and local density as predictor variables, the bias is analyzed analytically using weighted distributions. The plot size producing the highest coefficient of determination is rather close to the size of the influence zone, but much larger plot sizes are needed for unbiased estimation. It is safe to measure density from a larger plot than that used for sample tree selection. The analysis may give insight for other cases in multilevel modeling where group variables are used to explain individual responses.