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Статті в журналах з теми "Pinus radiata Growth"
1
Montalbán, Itziar A., Ander Castander-Olarieta, Cathy L. Hargreaves, Keiko Gough, Cathie B. Reeves, Shaf van Ballekom, Tomás Goicoa, María Dolores Ugarte, and Paloma Moncaleán. "Hybrid Pine (Pinus attenuata × Pinus radiata) Somatic Embryogenesis: What Do You Prefer, Mother or Nurse?" Forests 12, no. 1 (December 31, 2020): 45. http://dx.doi.org/10.3390/f12010045.
Повний текст джерелаАнотація:
Development of hybrid pines of Pinus radiata D. Don for commercial forestry presents an opportunity to diversify the current resource of plant material. Climate change and different land uses pose challenges, making alternative species necessary to guarantee wood and non-wood products in the future. Pinus radiata var. cedrosensis × Pinus attenuata hybrid possesses different attributes, such as tolerance to drought conditions, better growth and resistance to snow damage at higher altitudes, and more importantly, different wood quality characteristics. Embryogenic cell lines were successfully initiated reciprocal hybrids using as initial explants megagametophytes, excised zygotic embryos and excised zygotic embryos plus nurse culture. However, the questions raised were: does the initiation environment affect the conversion to somatic plantlets months later? Does the mother tree or the cross have an effect on the conversion to somatic plantlets? In the present work we analysed the maturation rate, number of somatic embryos, germination rate, and the ex-vitro growth in cell lines derived from different initiation treatments, mother tree species, and crosses. Differences were not observed for in vitro parameters such as maturation and germination. However, significant differences were observed due to the mother tree species in relation with the ex-vitro growth rates observed, being higher those in which P. radiata acted as a mother. Moreover, embryogenic cell lines from these hybrids were stored at −80 °C and regenerated after one and five years.
2
Cremer, K. W. "Relations between reproductive growth and vegetative growth of Pinus radiata." Forest Ecology and Management 52, no. 1-4 (September 1992): 179–99. http://dx.doi.org/10.1016/0378-1127(92)90501-y.
Повний текст джерела
3
Matsumura, Junji, and Brian G. Butterfield. "MICROFIBRIL ANGLES IN THE ROOT WOOD OF PINUS RADIATA AND PINUS NIGRA." IAWA Journal 22, no. 1 (2001): 57–62. http://dx.doi.org/10.1163/22941932-90000268.
Повний текст джерелаАнотація:
Microfibril angles of the S2 layer and tracheid lengths were measured in the root wood of Pinus nigra, and the root and stem wood of Pinus radiata. Within 10 mm (the first 2–3 growth rings) from the root centre, microfibril angles were large in the wood of both species, ranging from 25° to 40°. Beyond 10 mm (the fourth growth ring and beyond) from the root centre, microfibril angles were small. This pattern of microfibril angle change in root wood differs from those normally found in stems where angles are large until the 10–15th rings. Root wood tracheid length also showed a different pattern in radial direction from that normally observed in stem wood. Tracheids of Pinus radiata root wood were long in the first ring, decreasing to the third ring and then increased to the seventh ring. Beyond the seventh ring tracheid length was stable at around 3 to 3.5 mm. It was noted that microfibril angles were not influenced by tracheid length in root wood.
4
Harris, J. M., and A. P. Singh. "Unusual growth patterns in short shoots of Pinus radiata." Canadian Journal of Botany 65, no. 2 (February 1, 1987): 280–85. http://dx.doi.org/10.1139/b87-039.
Повний текст джерелаАнотація:
Short shoots and the needles that they bear usually persist for about 3 years on stems and branches of Pinus radiata D. Don. As the main axis thickens with secondary growth, short shoots may elongate by four times their original length, during which process xylem elements become embedded in the stem as "needle trances," although the external shoots appear to remain unchanged. This report describes how elongation in both xylem and phloem results from the insertion of new vascular elements derived from marginal cells of radial parenchyma bands. There was no evidence that the apical meristem contributes to this growth. Possible mechanisms for elongation of pith and cortex are also described.
5
Neilsen, W. A., and E. A. Pinkard. "Effects of green pruning on growth of Pinus radiata." Canadian Journal of Forest Research 33, no. 11 (November 1, 2003): 2067–73. http://dx.doi.org/10.1139/x03-131.
Повний текст джерелаАнотація:
Pruning of plantation trees is completed to produce knot-free timber and veneer logs, thus increasing the value of the plantation. A long-term study (11 years) was established to investigate the effects of selective pruning on radiata pine (Pinus radiata D. Don) stem growth. The 175 stems selected for the experiment had been pruned to 2.4 m at 6 years of age. At ages 8 and 10, the trees were pruned to 45%, 60%, or 75% of tree height and growth was compared with a control (first lift pruned only). Pruning to 45% of tree height had no effect on growth to age 13 years. Responses to the other treatments were apparent soon after pruning and continued until measurements ceased at 17 years of age. Pruning to 60% or 75% of tree height at second lift reduced diameter increment, and increment decreased as pruning severity increased. There was a further separation of the growth curves following third-lift pruning to 60% or 75% of tree height. The results suggested that maintaining a live crown ratio of 55% would minimize effects of pruning on diameter growth. The effect of severe pruning on diameter increment was greater for subdominant trees than for dominant stems. Pruning had less effect on height than diameter increment, but all treatments involving pruning to 75% of height at third lift resulted in trees that were approximately 10% shorter than unpruned trees at 13 years of age. More severe second-lift pruning resulted in smaller diameter over stubs at the time of third-lift pruning. Second-lift pruning to 60% of total height produced acceptable diameter over stubs. Implications for management are discussed.
6
Gous, S. F., B. Richardson, and M. O. Kimberley. "Optimum spot weed control treatment for a New Zealand radiata pine (Pinus radiata) plantation." New Zealand Plant Protection 56 (August 1, 2003): 56–60. http://dx.doi.org/10.30843/nzpp.2003.56.6032.
Повний текст джерелаАнотація:
A trial was established in the South Island of New Zealand to investigate the response of Pinus radiata to varying the area and duration of weed control around individual trees Results after six years demonstrated that weed control was essential to ensure maximum survival and growth of Pinus radiata seedlings Maintaining weed control for two seasons following planting resulted in marginally higher stand productivity than where weed control was applied in the year of planting only A modelling approach was used to determine treatment effects in terms of a time difference and to make inferences on longterm treatment effects Without weed control tree volume six years after planting was more than 15 years behind trees given complete weed control Spot vegetation control resulted in similar tree growth to total control as long as the area and duration of weed control was greater than a 1 m spot maintained for 1 year
7
Smethurst, Philip, Andrew Knowles, Keith Churchill, Ann Wilkinson, and Arthur Lyons. "Soil and foliar chemistry associated with potassium deficiency in Pinus radiata." Canadian Journal of Forest Research 37, no. 6 (June 2007): 1093–105. http://dx.doi.org/10.1139/x06-307.
Повний текст джерелаАнотація:
We required an improved understanding of K deficiency and diagnosis in Pinus radiata D. Don (radiata pine). A rapid growth response to K fertilization (100 kg·ha–1) in the presence of weed control confirmed K deficiency in a 2-year-old stand. Tree growth did not respond to N fertilization, and weed control alone appeared insufficient to maximize tree growth. Temporal patterns in visual symptoms of K deficiency suggested they were worst at the end of a drought, and improved after several months of above-average rainfall that coincided with an increase in soil temperature. Soil chemistry generally responded predictably to fertilization, but K fertilization increased soil solution Ca and Mg concentrations without changing exchangeable concentrations. With weed control, a doubling of stem growth response to K fertilizer was associated with a 270% increase in soil solution K (natural variation amongst control plots), 51% increase in exchangeable K, and 39% increase in foliar K. Relationships between seedling growth and hydroponic concentrations of K were consistent with the incidence of K deficiency in the field; predicting these deficiencies using soil exchangeable concentrations was less clear. This study advances the interpretation of soil and foliar chemistry in relation to K and Mg deficiency in P. radiata.
8
Jayawickrama, K. J. S., and C. Balocchi. "Growth and form of provenances of Pinus radiata in Chile." Australian Forestry 56, no. 2 (January 1993): 172–78. http://dx.doi.org/10.1080/00049158.1993.10674605.
Повний текст джерела
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Guzmán, Gustavo, Timo Pukkala, Marc Palahí, and Sergio de-Miguel. "Predicting the growth and yield of Pinus radiata in Bolivia." Annals of Forest Science 69, no. 3 (December 6, 2011): 335–43. http://dx.doi.org/10.1007/s13595-011-0162-3.
Повний текст джерела
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Vargas, Felipe, Carlos A. Gonzalez-Benecke, and Rodrigo Ahumada. "Long-Term Responses to Competing Vegetation Management for Pinus radiata." Forests 14, no. 1 (December 28, 2022): 55. http://dx.doi.org/10.3390/f14010055.
Повний текст джерелаАнотація:
Numerous studies have been carried out to quantify the response to competing vegetation control (CVC) in P. radiata plantations. Most of these publications have reported on the early response in tree growth; however, a knowledge gap exists regarding the growth responses throughout the rotation. In this study, we analyzed the long-term response of P. radiata plantations across a gradient of seven sites in central Chile. Treatments included a no-action control, two spot (circular) areas of competing vegetation control using herbicides around individual P. radiata seedlings (spot herbicide application of 0.75 and 1.5 m), and total competing vegetation control using herbicides. Additionally, three different timings for control regimes were included (0, 1, and 2 years after planting). Competing vegetation biomass abundance during the first growing season ranged from 0.6 to 5.7 Mg ha−1 across all sites. The total competing vegetation control treatment maintained for 2 years (TotalY012) showed the largest gain in stem volume per hectare (VOL) in most of the sites. The sites included in this study showed contrasting values in productivity, having volume yields for the TotalY012 treatment ranging from 238 m3 ha−1 at the site with the lowest annual rainfall (age 12 years) to 471 m3 ha−1 at the southern site (age 14 years). Across all sites, maximum gain in VOL ranged between 21 and 175 m3 ha−1 at age 11 to 14 years and was linearly correlated to the amount of competing biomass controlled during the first year after planting. At the southern, wetter site, plots with only pre-planting spot herbicide application achieved 87% of VOL of plots with TotalY012. Our results suggest that CVC improved the availability of resources at the site for P. radiata seedlings, increasing volume production by reducing environmental constraints to tree growth differentially at each site.
Дисертації з теми "Pinus radiata Growth"
1
Zhao, Weizhong. "Growth and yield modelling of Pinus radiata in Canterbury, New Zealand." Thesis, University of Canterbury. Forestry, 1999. http://hdl.handle.net/10092/7148.
Повний текст джерелаАнотація:
During this study two growth and yield models were developed for Pinus radiata D.Don plantations in Canterbury, New Zealand, namely CanSPBL and CanJuv. CanSPBL is a model for the whole rotation of stands owned by the Selwyn Plantation Board Limited in Canterbury. CantJuv is a model for juvenile growth from after planting to before thinning in Canterbury. An existing stand growth and yield model CANTY was examined using a newly established relational database of PSP measurements. Projection bias was shown for mean top height, basal area per hectare and volume per hectare.
Height-diameter relationships were modelled for estimating individual tree height and mean top height. Of the sixteen functional forms evaluated the Petterson equation with exponent -5 and the two-parameter Richards' equation led to the smallest mean square error at stand level. Incorporating stand age, site index and altitude into the selected Petterson equation reduced the mean square error by 72% for a pooled regional data set.
The new model, CanSPBL, was achieved with precision at both stand and tree level.
The components of the stand model include mean top height, basal area per hectare, stems per hectare, volume per hectare and diameter distribution. The inclusion of altitude into a chosen polymorphic Schumacher difference equation significantly reduced mean square error by 17% for mean top height and 41% for basal area. An examination of this stand model using two sources of data at plot and stand levels showed little apparent bias.
Two main model components of tree diameter and tree mortality were developed to complete an individual-tree projection system. For projection of diameter, an approach based on relative basal area was found best, compared with many sigmoid difference equations. A logistic regression procedure showed that relative diameter, altitude, the interaction between initial stocking and projection interval length, and site index were significantly correlated to tree mortality.
Nine sets of experimental data and thirty-one temporary plots were used to refine the juvenile growth model of stand level, CanJuv. The components of the model were mean top height, basal area, sectional area at ground level, and survival. Regression analyses identified age, annual rainfall and weeding as the significant factors in determining growth and mortality.
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Guy, Andrew Cleveland. "An Improved Germination Protocol for Pinus radiata, Applicable for Investigation into the Effects of Exogenously Supplied Amino Acids on Seedling Growth, Under Glasshouse and Lab Conditions." Thesis, University of Canterbury. Biological Sciences, 2013. http://hdl.handle.net/10092/8711.
Повний текст джерелаАнотація:
The two main goals in this research were: (i) to investigate Pinus radiata seed germination methods, identifying areas where improvements could be made and developing a germination protocol applicable for studies under sterile and glasshouse conditions, and (ii) to investigate the potential of L-amino acids as nitrogen fertilisers or growth regulating substances, specifically during early seedling growth of P. radiata.
There is a lack of a standard protocol for seed germination of radiata pine. Therefore, a systematic approach was undertaken to develop a germination protocol which was applicable for both commercial and scientific use. It was found that a high percentage of P. radiata seed germination was observed without the need for nutrient-rich plant tissue culture media, stratification, scarification, or elaborate surface sterilisation of the seed. This led to the development of an improved protocol that was simple and relatively inexpensive, resulting in a high percentage of rapid and uniform germination. The main features of this improved germination protocol include: (i) a single-step surface sterilisation with ethanol for 30 seconds, (ii) pre-sowing, imbibition and drying of seeds overnight, and (iii) use of autoclaved moist vermiculite as a germination substrate.
L-amino acids are commonly used as organic nitrogen sources for plant nutrition. There is also evidence that exogenously supplied L-amino acids can have effects on plant growth beyond a nitrogen nutrition effect and that these effects are plant species dependent. Since these L-amino acid effects have not previously been investigated in P. radiata, the effects of each of the 20 commonly occurring protein L-amino acids on radiata pine growth were investigated. Five L-amino acids (Arginine, Aspartic acid, Proline, Lysine and Serine) were identified as having nitrogen nutrition independent effects. Under laboratory conditions these effects were determined to be concentration dependent and could therefore be of physiological significance. Under glasshouse conditions, the L-amino acid effects were subject to the influences of soil factors. The L-amino acid effects identified in this research can be considered novel and warrant further investigation.
3
Kirongo, Balozi Bekuta. "Modelling growth responses of juvenile radiata pine (Pinus radiata D. Don) clones subjected to different weed competition levels in Canterbury, New Zealand." Thesis, University of Canterbury. Forestry, 2000. http://hdl.handle.net/10092/7496.
Повний текст джерелаАнотація:
For a given site, species, genotype and management regime, tree growth is related to the amount, and temporal- and spatial-distribution of foliage, as governed by the prevailing below- and above-ground environment and intercepted photosynthetically active radiation. Canopy foliage budgets, therefore can provide first hand information about how trees cope with adverse environmental conditions and resource deficits in more subtle ways than height and diameter which are not as sensitive to changes in resource availability as leaf area. Process-oriented research, aimed at quantifying needle mortality within canopies and foliage growth dynamics of young radiata pine clones growing under varying competition gradients, therefore has the potential to improve decision tools for foresters charged with establishing tree crops.
During this study growth responses of juvenile radiata pine (Pinus radiata D. Don) clones to variable weeding micro-environments during the first 3 years after outplanting were evaluated. The study was established in a dry site on the Canterbury plains of the South Island of New Zealand. A complete randomised block design replicated three times in a split-plot layout was used. Four weeding treatments; 1) complete weeding, 2) 2 m diameter spots, 3) 1 m diameter spots around plants and 4) a control, formed the main plots while seven clones formed the sub-plots. Leaf area and specific leaf area spatial distribution as well as fascicle mortality in time and space were quantified. Annual crown foliage budgets of 3 of the clones were evaluated using regressions developed from limited destructive sampling and image analysis techniques. Changes in mean relative growth rate (RGR) with tree size and age were evaluated by quantifying the morphological and physiological terms of the RGR expansion, to allow for changes in these terms;
RGR = ULR * SLA * LWR
where,
RGR = relative growth rate,
ULR = unit leaf rate,
SLA = specific leaf area and
LWR = leaf weight ratio.
Relative growth rate declined with tree age and size for trees in all weeded treatments but increased with age and size for trees in the unweeded control. The decline in RGR was mainly due to reduced ratio of dry matter turn over to leaf area i.e. unit leaf rate. Of tree age and size, size was the major factor influencing the decline in RGR. Of the 3 clones studied in detail, clone 3 had a different above ground carbon allocation strategy to clones 1 and 2, especially as regards leaf weight ratio and leaf area ratio.
Weeding influenced tree growth considerably. Significant clonal differences in height and basal-basal area were found. Trees growing in weed-free environments made favourable use of their micro-environments and significant genotype-by weeding interaction was present for height. However, no "rich-kid" effect (some trees growing in weed-free micro-environments performing poorly) was found. Provisional models of height, basal-basal area and tree survival integrating weeding and clonal effects were also developed.
One of the significant findings from this study was the strong evidence against the constant RGR model which has been used by many researchers of tree growth analysis. The results further demonstrated that trees growing with weeds were predisposed to perform poorly due to reduced canopy production as well as having higher proportions of older, less efficient foliage.
The results from this study lay the framework to explicitly quantify clonal responses to resource deficits arising from management inputs using variables directly involved in canopy production (i.e. leaf area).
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Bloomberg, Mark. "Modelling germination and early seedling growth of radiata pine." Lincoln University, 2008. http://hdl.handle.net/10182/681.
Повний текст джерелаАнотація:
Background: This study seeks to model aspects of the regeneration of radiata pine (Pinus radiata D.Don) seedlings under a range of environmental conditions. This study investigated whether “hybrid” mechanistic models, which predict plant growth and development using empirical representations of plant physiological responses to the environment, could provide a realistic alternative to conventional empirical regeneration models. Objectives: The objectives of this study were to 1) identify the functional relationships between the environmental conditions controlling germination, establishment and growth of radiata pine seedlings, under a range of those environmental conditions as specified by temperature and available light and soil water; and 2) specify those functional relationships in hybrid mechanistic (“hybrid”) models. Methods: Radiata pine seedling germination and growth were measured under controlled environmental conditions (incubators for seed germination, growth cabinets for seedlings), and results used to adapt, parameterise and test two published hybrid models; one for germination (the hydrothermal time model); and one for seedling growth in the first six months after germination, based on plant radiation use efficiency (RUE). The hydrothermal model was tested by incubating commercial radiata pine seeds under factorial combinations of temperature and water potentials where germination was likely to occur (12.5 ºC to 32.5 ºC and 0 MPa to –1.2 MPa.). 100 seeds were germinated for each factorial combination. The hydrothermal germination model was fitted to the germination data using non-linear regression modles, will allowed simultaneous estimation of all modle parameters. Seedlings were grown in controlled growth cabinets, and their RUE was calculated as the ratio of net primary production (NPP, specified in terms of an increase in oven dry biomass), to PAR intercepted or absorbed by a seedling. Estimation of seedling RUE required development of novel techniques for non-destructive estimation of seedling oven dry weight, and measurement of PAR interception by seedlings. The effect of varying PAR flux density on RUE was tested by measuring RUE of seedlings grown at 125, 250 and 500 µmol m⁻² s⁻¹. In a second experiment, the effect of deficits in available soil water on RUE was tested by measuring RUE of seedlings grown under 250 µmol m⁻² s⁻¹ PAR flux, and at different levels of available soil water. Available soil water was specified by a soil moisture modifier factor (ƒθ) which ranges between 1 for moist soils and 0 for soils where there is insufficient water for seedling growth. This soil moisture modifier had not previously been applied in studies of tree seedling growth. Temperatures for both seedling experiments were a constant 17.5 ºC (day) and 12.5 ºC (night). Results: Hydrothermal time models accurately described radiata pine seed germination. Model predictions were closely correlated with actual seed germination over the full range of temperature and water potentials where germination was likely to occur (12.5 ºC to 32.5 ºC and 0 MPa to –1.2 MPa. The minimum temperature for germination (base temperature) was 9.0 ºC. Optimum temperatures for germination ranged from ~20ºC for slow-germinating seeds to ~27 ºC for the fastest germinating seeds. The minimum water potential for seed germination varied within the seed population, with an approximately normal distribution (base water potential = –1.38 MPa, standard deviation of 0.48 MPa). In the process of developing the model, a novel explanation for the decline in germination rates at supra-optimal temperatures was developed (Section 3.4.6), based on earlier models proposed by Alvarado & Bradford (2002) and Rowse & Finch-Savage (2003). This explanation was that the decline in germination rate was not driven just by temperature, but by accumulated hydrothermal time above the base temperature for germination (T₀). This in turn raised the base soil water potential (Ψb) towards 0, so that the reduction in germination rate arose from a reduced accumulation of hydro-time, rather than from thermal denaturation of enzymes facilitating germination – the conventional explanation for non-linear accumulation of thermal time at supra-optimal temperatures for plant development. Upwards adjustment (towards 0 MPa) of base water potentials of germinating seeds occurred also at very cold temperatures in combination with high water potentials. In both cases (very cold or else supra-optimal temperatures) this upwards adjustment in base water potentials prevented germination of part of the seed population, and is proposed as a mechanism which enables seed populations to “hedge their bets” when germinating under less than ideal germination conditions. RUE of young germinated radiata pine seedlings growing in a controlled growth cabinet was not significantly different over a range of constant PAR flux densities. Mean RUE’s were 3.22, 2.82 and 2.58 g MJ⁻¹ at 125, 250 and 500 µmol m⁻² s⁻¹ respectively. In the second experiment, the novel use of a soil moisture modifier (ƒθ) to predict RUE of seedlings subjected to water stress proved successful within a limited range of soil water stress conditions. Measured seedling transpiration and stomatal conductance were closely correlated but seedling photosynthesis was less correlated with available soil water. This result suggests that photosynthesis was not coupled with stomatal conductance when PAR flux was 250 µmol m⁻² s⁻¹, which is well below saturating irradiance for C₃ plants. Conclusions: The use of hybrid, quasi-mechanistic models to describe tree seedling growth has been seldom explored, which necessitated the development of novel experimental and analytical techniques for this study. These included a predictive model of germination decline at sub- and supra-optimal temperatures; a method for accurately estimating seedling dry weights under a range of PAR flux densities; and a novel method for estimating light interception by small seedlings. The work reported in this thesis showed that existing hybrid models (the hydrothermal time germination model and the RUE model) can be adapted to model germination and growth of radiata pine seedlings under controlled environmental conditions. Nonetheless, further research is needed before the models can be confidently used as an alternative to conventional empirical models to model regeneration in “real-world” forests. Research priorities are the performance of hydrothermal germination models under variable field conditions, and the use of the soil moisture modifier for seedlings growing on a range of soil textures and under a range of PAR fluxes.
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Chikumbu, Vavariro. "Growth responses to fertilizer application of thinned, mid-rotation Pinus radiata stands across a soil water availability gradient in the Boland area of the Western Cape." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17828.
Повний текст джерелаАнотація:
Thesis (MscFor)--Stellenbosch University, 2011.ENGLISH ABSTRACT: The purpose of the study was to investigate the effect of mid rotation fertilizer application on leaf area index (LAI), basal area and volume increment in thinned Pinus radiata stands on the most common soils of the Boland region in the Western Cape. The study was conducted on a range of sites in the Boland region of MTO Forestry Company, chosen to reflect the two most common soil types and a water availability gradient in each soil type. A factorial combination of fertilizer treatments with three levels each for nitrogen (N) at 0, 100 and 200 kg ha-1 and phosphorus (P) at 0, 50 and 100 kg ha- 1 was used. This design was replicated four times across a gradient of water availability for each of the two common soil groups, forming a complete trial series. All replications were laid out in P. radiata stands that had received their mid-rotation thinning prior to treatment implementation. LAI, diameter at breast height and height measurements as well as foliar analysis were determined before the implementation of the study in 2008 and then subsequently at predetermined intervals in 2009 and 2010. Leaf area index and stem volume increment were measured in order to evaluate the influence on growth efficiency. LAI was estimated using the gap fraction method with the use of a ceptometer. Volume increment was calculated using diameter and height measurements and basal area was calculated by means of diameter measurements. The abovementioned growth responses were then used to determine the effect of increased nutrient availability on stand growth. There were no significant interactions detected between any of the factors, N, P and water availability class in their effect on LAI, basal area, volume increment and growth efficiency. LAI increment responded significantly to N and P in the first year but only to P in the second year after treatment. Significant basal area responses to N and P were recorded in the second but not the first year. This might have been due to the fact that trees had to re-build their canopies after thinning before a basal area response could be obtained. For the variables where an analysis of total growth response over the two year period was done, basal area increment and volume increment significantly responded to the application of nitrogen but not to phosphorus. Growth efficiency was not significantly influenced by either nitrogen or phosphorus over the full two year monitoring period. Water availability class consistently and significantly influenced basal area increment, volume increment and growth efficiency over the two year period as well as during year one and year two. The best responses generally occurred as a result of the additive effects of N and P. The growth response did not remain the same across the water availability classes. The wetter sites tended to have greater responses than the drier sites. Although these are still early results, the growth responses could be attributed to an increase in LAI. Nutrient analysis through vector analysis indicated that the additional N and P from fertilizer application were taken up by the trees thereby resulting in greater LAI and increased stem wood production.
AFRIKAANSE OPSOMMING: Die studie het ten doel gestel om die effek van mid-rotasie bemesting op blaar oppervlak indeks (BOI), basale oppervlakte- en volume aanwas te ondersoek in gedunde opstande van Pinus radiata op die mees algemene grondtipes van die Bolandstreek, Wes-Kaapland. Eksperimente is uitgelê oor 'n reeks van groeiplekke in die Bolandstreek wat gekies is om 'n water beskibaarheidsgradient te verteenwoordig oor elk van die twee mees algemene grondtipes. 'n Faktoriaal-kombinasie van kunsmisbehandelings met drie vlakke elk van stikstof [(N) teen 0, 100 en 200 kg ha-1] en fosfor [(P) teen 0, 50 en 100 kg ha-1] is toegedien. Hierdie ontwerp is vier maal herhaal oor 'n gradient van grondwater beskikbaarheid, oor elk van die twee mees algemene grondtipes, om sodoende 'n volledige eksperimentele reeks te vorm. Elke herhaling is uitgelê in 'n P. radiata opstand wat reeds 'n mid-rotasie dunning ondergaan het voor implementering van die kunsmis behandelings. Metings van BOI, deursnee op borshoogte, boomhoogte asook blaarmonsters is geneem voor implementering in 2008 en daarna met vooraf bepaalde tussenposes in 2009 en 2010. Die BOI en stam volume aanwas is bepaal om die effek van behandelings op groeieffektiwiteit te evalueer. Die gaping fraksie tegniek is gebruik om BOI te skat met behulp van 'n sonvlek septometer. Volume aanwas is bereken vanaf deursnee en hoogtemetings en basale oppervlak aanwas vanaf deursnee-metings. Metings van al bogenoemde groeireaksies is gebruik om die effek van verhoogde voedingstof beskikbaarheid op opstandsgroei te evalueer. Daar was geen betekenisvolle interaksies tussen enige van die faktore N, P of water beskikbaarheidsklas met betrekking tot reaksies op BOI, basale oppervlak- en volume aanwas of groei-effektiwiteit nie. Die BOI het betekenisvol gereageer op N en P in die eerste jaar, maar slegs op P in die tweede jaar na behandeling. Basale oppervlakte aanwas is betekenisvol verbeter deur N en P in die tweede jaar maar nie in die eerste jaar nie. Dit is waarskynlik as gevolg van die feit dat opstande eers hul kroondak moes herstel (na dunnings) voordat 'n reaksie in basale oppervlak verkry kon word. Vir die veranderlikes waar 'n analise van die groeireaksie oor die volle twee jaar moniteringsperiode gedoen is, het basale oppervlak- en volume aanwas betekenisvol gereageer op stikstof maar nie op fosfor nie. Groei-effektiwiteit is nie betekenisvol geaffekteer deur N of P oor die volle twee jaar moniteringsperiode nie. Water beskikbaarheidsklas het basale oppervlak en volume aanwas asook groei-effektiwiteit betekenisvol en voortdurend beïnvloed in die eerste en tweede jaar, asook gedurende die volle twee jaar moniteringsperiode. Die beste groeireaksie is oor die algemeen verkry waar N en P gesamentlik toegedien is en waar dus aanvullende reaksies verkry is. Groeireaksies het betekenisvol verskil na gelang van water beskikbaarheidsklas, met die grootste reaksie op die natste groeiplekke. Hoewel hierdie vroeë resultate is, kan ons die meganisme van die reaksie primêr toeskryf aan 'n toename in BOI. Vektor analise van blaar voedingstof vlakke het aangedui dat addisionele N en P na kunsmis toediening opgeneem is, wat die weg gebaan het vir 'n toename in BOI en verhoogde volume aanwas.
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Rubilar, Rafael Alejandro. "Environmental constraints on growth phenology, leaf area display, and above and belowground biomass accumulation of Pinus radiata (D. Don) in Chile." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-12062005-135049/.
Повний текст джерелаАнотація:
Environmental site-specific constraints on shoot, branch, and leaf area growth and phenology were investigated during the third and fourth growing seasons in two-year-old radiata pine plantations established under a factorial combination of soil preparation, fertilization, and weed control at three contrasting textural and climatic soil-site conditions in the Central Valley of Chile. During October 2002 and June 2005, biweekly measurements of foliage accretion, branch, and stem growth were obtained together with periodical evaluations of foliage senescence. At each site, tree growth, aboveground biomass, belowground biomass, total biomass, aboveground:belowground biomass ratio, and leaf area index increased mainly by weed control (WC). The large gradient of tree growth and biomass accumulation among sites, and within sites varying in response to WC, was mainly attributed to large differences in soil water availability and possibly atmospheric water demand differences within sites. A linear relationship was established between LAI and stand growth across sites. The slope of the relationship (stemwood growth efficiency, GE) varied from 2.9 m3ha-1year-1 to 6.8 m3ha-1year-1 per unit of leaf area, with lower growth efficiencies found on sites with the greater water constraints. Phenology of growth was little affected by site or silvicultural treatments. Seasonal differences in the patterns of growth were mainly observed among sites for diameter, with longer growing seasons at sites with lower water limitations. In contrast, strong site and silvicultural treatments effects were observed on tree morphology. Trees where water limitations were more severe exhibited fewer and shorter flushes of height growth. The negative effects of soil water limitations, were at least partially ameliorated by silvicultural treatments that had been applied three years previously. Resource availability constraints during the mid to late growing season affected diameter growth more than height growth. Phenology of fascicle elongation indicated that sites with water and nutritional constraints ended fascicle elongation earlier during a growing season. Phenology of fascicle senescence indicated that maximum needlefall occurred during the summer and autumn seasons. No differences in silvicultural treatments were observed in foliage accretion or senescence patterns. Foliage longevity increased for sites with water and nutrient limitations.
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Arneth, Almut. "Fluxes of carbon and water in a Pinus radiata plantation and a clear-cut, subject to soil water deficit." Lincoln University, 1998. http://hdl.handle.net/10182/1955.
Повний текст джерелаАнотація:
This thesis investigates the abiotic control of carbon (C) and water vapour fluxes (FCO₂ and E, respectively) in a New Zealand Pinus radiata D. Don plantation and a nearby clearcut. It concentrates on the limitation of these fluxes imposed by growing season soil water deficit. This results from low precipitation (658 mm a⁻¹) in combination with a limited root zone water storage capacity of the very stony soil (> 30% by volume). The thesis analyses results from seven eddy covariance flux measurement campaigns between November 1994 and March 1996. The study site was located in Balmoral Forest, 100 km north-west of Christchurch (42° 52' S, 172° 45' E), in a (in November 1994) 8-year-old stand. One set of measurements was conducted in an adjacent clearcut. Ecosystem flux measurements were accompanied by separate measurements of ground fluxes and of the associated environmental variables. Flux analysis focussed on the underlying processes of assimilation (Ac), canopy stomatal conductance (Gc) and respiration (Reco), using biophysical models coupled to soil water balance and temperature subroutines. Aiming to link time inegrated net ecosystem C (NEP) to tree growth, sequestration in tree biomass (NPP) was quantified by regular measurements of stem diameter using allometric relationships. Average rates of FCO₂ and E were highest in spring (324 mmol m⁻² d⁻¹ and 207 mol m⁻² d⁻¹, respectively) when the abiotic environment was most favourable for Gc and Ac. During summer, fluxes were impeded by the depletion of available soil water (θ) and the co-occurrence of high air saturation deficit (D) and temperature (T) and were equal or smaller than during winter (FCO₂ = 46 mmol m⁻² d⁻¹ in summer and 115 mmol m⁻² d⁻¹ in winter; E = 57 and 47 mol m⁻² d⁻¹, respectively). With increasingly dry soil, fluxes and their associated ratios became predominantly regulated by D rather than quantum irradiance, and on particularly hot days the ecosystem was a net C source. Interannually, forest C and water fluxes increased strongly with rainfall, and the simultaneously reduced D and T. For two succeeding years, the second having 3 % more rain, modelled NEP was 515 and 716 g C m⁻² a⁻¹, Ac 1690 and 1841 g C m⁻² a⁻¹ and Reco 1175 and 1125 g C m⁻² a⁻¹. NEP / E increased in wetter (and cooler) years (1.3 and 1.5 g kg⁻¹), reflecting a relatively larger gain in NEP. Responding mainly to increased rainfall during commonly dry parts of the year (ie summer), and reflecting the otherwise benign maritime climate of New Zealand, NEP during the winter months could exceed NEP during the middle of the notional tree growing season. Annual Ac, NEP, and NPP were strongly linearly related. This relation did not hold during bi-weekly periods when the processes of intermediate C storage were influential. Separate knowledge of tree growth and C fluxes allowed quantification of autotrophic, and heterotrophic respiration (Rhet≈ 0.4 NEP), as well as fine-root turnover (≈0.2 NEP). The ratio of NEP and stem volume growth was conservative (0.24 t C m⁻³) and allows a direct connection to be made between ecosystem carbon fluxes and forest yield tables. In the absence of living roots, the clearcut flux measurements demonstrated the expected limitation of Rhet by soil temperature (Ts) and θ. However, an additional 'pumping effect' was discovered at the open site whereby turbulence increased CO₂ efflux considerably when the soil surface was wet. Accounting for the combined effects of Ts, θ and turbulence, annual Rhet at the clear-cut site (loss to the atmosphere) was »50 % of NEP (C sequestered from the atmosphere) in the nearby forest. Clearly, there is an important contribution of C fluxes during early stages of ecosystem development to the total C sequestered over the lifetime of a plantation.
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Badenhorst, Johannes Jurie. "The effect of fertilising pinus radiata stands at mid rotation age in the Western Cape Province on leaf area, growth efficiency and stand productivity." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4375.
Повний текст джерелаАнотація:
Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: Mid rotation fertiliser application is generally practised in forestry to enhance nutrient availability in areas were soils are impoverished and do not provide sufficient nutrients for high productivity. Generally speaking there is great potential for mid rotation fertiliser in pine plantations, but stand and site characteristics such as water availability, soil depth, stand density and available nutrients need to be considered before fertiliser treatments are implemented. Foliar nutrient analyses were used to estimate nutrient availability. These levels were measured throughout the study and were used to implement specific fertiliser treatments that would boost nutrient availability. Treatments consisted of an unfertilised control, a single fertiliser application (1F) and two fertiliser applications over two consecutive years (2F). Leaf area index (LAI) and stem volume increment were measured in order to evaluate its influence on growth efficiency. LAI was estimated using the gap fraction method with the use of a ceptometer. Volume increment was calculated with diameter and height measurements. Basal area was calculated by means of diameter measurements. These growth responses were used to determine the effect of increased nutrient availability and although increases were found in LAI, volume increment, basal area increment and growth efficiency, none were significant. The lack of significance may be due to relatively large variations in other factors such as stand density and initial volume of the experimental plots. The 18 month monitoring period apparently did not allow complete reaction time to increased nutrient availability and limited our understanding of the responses somewhat. Despite this, the magnitude of some growth responses was large as nutrient ratios in the foliage increased to levels within the norms range. Increases in current annual volume increment (CAI) of 3.48 m3 ha-1 a-1 and 3.62 m3 ha-1 a-1 in 1F plots at Grabouw and La Motte plantations indicated that it may be economically feasible to fertilise at mid rotation age as the NPV and IRR increased over a projected 25 year rotation. The Grabouw site had the most significant response with regards to CAI in 2F treatment with a mean volume increment of 5.43 m3 ha-1 a-1. The mechanism of the response was examined further by taking water availability and soil characteristics into account. The seasonal climatic effect (length of the moisture growing season) had a significant influence on the response to fertilisation.
AFRIKAANSE OPSOMMING: Die toediening van mid-rotasie bemesting word algemeen in bosbou toegepas om voedingstofbeskikbaarheid te verhoog in areas waar voedingstowwe onvoldoende is vir hoë produktiwiteit. Daar is oor die algemeen ruim potensiaal vir mid-rotasie bemesting in denne plantasies, maar eienskappe soos waterbeskikbaarheid, gronddiepte, opstanddigtheid en beskikbaarheid van voedingstowwe moet in ag geneem word voor optimum bemestingtoedienings bepaal kan word. Blaaranalise is gebruik om voedingstofbeskikbaarheid in plantasies te skat. Hierdie voedingstofvlakke is deurgans gemeet en is gebruik om spesifieke bemestingsbehandelings te implementeer wat voedingstofbeskikbaarheid kon opstoot. Behandelings het bestaan uit ‘n onbemeste kontrole, ‘n eenmalige kunsmistoediening (1F) en twee kunsmistoedienings in opeenvolgende jare (2F). Blaar oppervlak indeks en toename in stamvolume is gemeet om die invloed daarvan op die effektiwiteit van groei te bepaal. Blaaroppervlakindeks is bepaal deur middel van die gapingfraksie metode met behulp van ‘n stralingsmeter. Toename in volume is bereken met stamdeursnee en hoogte meetings. Basale oppervlakte is bereken deur middel van deursnee metings. Hierdie groeireaksies is gebruik om die effek van verbeterde voedingstofbeskikbaarheid te bepaal. Al die groeireaksies het toegeneem maar was nie statisties beduidend nie. Die gebrek aan beduidende toename kan toegeskryf word aan variasies in opstandsdigtheid en oorspronklike volume van die bome in die navorsingspersele. Die toetstydperk van 18 maande het moontlik nie genoeg tyd gegee vir die bome om op die toename in voedingstofbeskikbaarheid te reageer nie. ‘n Goeie groeirespons is wel waargeneem waar die voedingstofverhoudings in die naalde aanvaarbare norme bereik het. Die toename in volume aanwas van tussen 3.48m3 ha-1 a-1 en 3.62 m3 ha-1 a-1 in 1F persele by Grabouw en La Motte plantasies het aangedui dat dit ekonomies lewensvatbaar is om op mid-rotasie ouderdom bemesting toe te dien aangesien die netto teenswoordige waarde en die interne opbrengs koers toegeneem het op ‘n geprojekteerde 25 jaar rotasie. Die persele op Grabouw plantasie het die mees beduidende respons getoon met betrekking tot huidige jaarlikse aanwas (5.43 m3 ha-1 a-1 in die 2F perseel). Die meganisme van die respons is verder nagevors met inagneming van waterbeskikbaarheid en grondeienskappe. Die seisoenale klimaatseffek (lengte van die vog-groeiseisoen) het ‘n beduidende impak op die respons tot bemesting.
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Wondifraw, Daniel. "The effect of site and cambial age on selected anatomical properties of." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/19902.
Повний текст джерелаАнотація:
Thesis (MScFor)--Stellenbosch University, 2012.ENGLISH ABSTRACT: The aim of this project was to determine the site effect- especially water availability - and the effect of cambial age on selected anatomical properties of Pinus radiata, in order to be able to predict possible changes in wood quality due to an expected change in climate. A second objective was to correlate ring and fibre properties, in order to determine, if ring properties could be used as a proxy to describe wood quality. The samples consisted of 12 trees, sampled at an age of 1 to 16 from six selected sites in the Western Cape, which ranged from water stressed to moist. Apart from the water availability all other external factors, such as elevation etc. were kept as equal as possible. Anatomical wood properties such as fibre length and fibre diameter, lumen diameter, cell wall thickness, ring width and earlywood/latewood ratio were determined and their change with cambial age and water availability was evaluated. Fibre length, fibre diameter and cell wall thickness increased with increasing cambial age, and ring width and earlywood/latewood ratio decreased with increasing cambial age. No significant correlations were found between any of the ring or fibre properties and water availability. Most of the fibre properties were significantly correlated with ring width and earlywood/latewood ratio when age was not considered as covariate, but showed no correlation when the age effect was excluded.
AFRIKAANSE OPSOMMING: Die doel van die projek was om die perseel se effek te bepaal, veral water beskikbaarheid, ten opsigte van die effek van kambium ouderdom en geselekteerde anatomiese eienskappe van Pinus radiata, om sodoende die moontike verandering in hout kwaliteit as gevolg van verwagte klimaatsverandering te voorspel. ‘n Tweede doelwit was om die ring en vesel eienskappe te korreleer en ook te bepaal of ring eienskappe gebruik kan word om hout kwaliteit te beskryf. Die monsters het bestaan uit bome van ses geselekteerde persele in die Wes Kaap en het gevarieer van ‘n water tekort na klam. Behalwe vir water beskikbaarheid is al die ander eksterne faktore, soos hoogte ens., konstant gehou waar moontlik. Anatomiese hout eienskappe soos vesel lengte en deursnee, sel deursnee, selwand dikte, ring wydte en E/L verhouding was bepaal asook die verandering met kambium ouderdom en water beskikbaarheid. Vesel lengte , vesel deursnee en selwand dikte het toegeneem met toename in kambium ouderdom, en ring wydte en E/L verhouding het afgeneem met toename in kambium ouderdom. Toename in water beskikbaarheid het gelei to afname in vesel lengte en selwand dikte, waar vesel deursnee, sel deursnee, E/L verhouding en ring wydte toegeneem het. Meeste van die vesel eienskappe het betekenisvol gekorrelleer met ring wydte en E/L verhouding wanneer ouderdom nie as ko-variant gebruik is nie.
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Forrester, David Ian, and davidif@unimelb edu au. "Mixed-species plantations of nitrogen-fixing and non-nitrogen-fixing trees." The Australian National University. Faculty of Science, 2005. http://thesis.anu.edu.au./public/adt-ANU20050202.164252.
Повний текст джерелаАнотація:
Mixed-species plantations of eucalypts and acacias have the potential to improve stand productivity over that of respective monocultures through the facilitative effect of nitrogen-fixation by acacias, and increased resource capture through above- and belowground stratification. However, growth in mixed-species plantations may not be improved compared to that of monocultures when competitive interactions outweigh the effects of improved nutrient availability and resource capture. Careful selection of sites and species is therefore critical to successfully improving stand productivity using mixed-species plantations. This study set out to examine some of the processes and interactions that occur in mixed-species plantations, and the effect nutrient and water availability can have on the growth of mixtures.
In three out of four mixed-species field trials examined in this study, growth was not increased in mixtures compared to monocultures. However, in the fourth field trial, heights, diameters, stand volume and aboveground biomass were higher in mixtures of E. globulus and A. mearnsii from 3-4 years after planting.
The range in outcomes from mixing species in these four trials shows that a fundamental understanding of the underlying processes is required to enable a greater predictive capacity for the circumstances under which mixtures will be successful. Therefore the growth dynamics, processes and interactions were examined in the mixtures of E. globulus and A. mearnsii. The difference in productivity between mixtures and monocultures in this trial increased with time up to age 11 years, when 1:1 mixtures contained twice the aboveground biomass of E. globulus monocultures. The positive growth response of trees in mixture compared to monocultures was the result of accelerated rates of nutrient cycling, a shift in C allocation and reductions in light competition through canopy stratification.
Nitrogen contents of foliage and soil clearly showed that A. mearnsii influenced the N dynamics in this trial. If these changes in N contents were due to N fixation by A. mearnsii, then about 51 and 86 kg N ha-1 yr-1 was fixed in the 1:1 mixtures and A. mearnsii monocultures, respectively. Nitrogen fixation was also examined using the natural abundance method. The delta15N values of foliage collected at 10 years were grouped according to the mycorrhizal status of the host plant. Therefore the discrimination of 15N during transfer from mycorrhizae to the host plant appeared to vary with mycorrhizal status, and the natural abundance of 15N was not used to quantify N fixation.
Rates of N and P cycling in litterfall were significantly higher in stands containing at least 25% A. mearnsii (more than 31 kg N ha-1 yr-1 and more than 0.68 kg P ha-1 yr-1) compared to E. globulus monocultures (24 kg N ha-1 yr-1 and 0.45 kg P ha-1 yr-1). Rates of litter decomposition and N and P release were about twice as high in 1:1 mixtures compared to E. globulus monocultures and were even higher in A. mearnsii monocultures. It is therefore important to select N-fixing species that are capable of cycling nutrients quickly between the plant and soil, and that have readily decomposable litter.
The total belowground C allocation was not significantly different between mixtures and monocultures (14 to 16 Mg C ha-1 yr-1). However, since aboveground net primary production was greater in 1:1 mixtures, the changes in nutrient availability appears to have increased total productivity (both above- and belowground), and reduced the proportion of C allocated belowground in mixtures compared to E. globulus monocultures.
In a pot trial containing mixtures of E. globulus and A. mearnsii both species grew larger in mixture than in monoculture at low N levels, and mixtures were more productive than monocultures. However, at high N levels, E. globulus suppressed A. mearnsii and mixtures were less productive than E. globulus monocultures. Similar effects were found for high and low levels of P.
Therefore resource availability can have a strong influence on the interactions and growth of mixtures. The productivity of mixtures may only be increased on sites where the resource for which competition is reduced in mixture is a major limiting growth resource. For example, if N is not a limiting growth factor then an increase in N availability from N-fixation may not increase growth, and the N-fixing species may compete for other resources such as soil P, moisture or light.
This study has shown that mixtures containing a N-fixing trees and a non-N-fixing trees can be more productive than monocultures, but that this increase in productivity will only occur on certain sites. Examination of the growth, interactions and processes that occurred in mixtures in this study provide useful information that can aid the selection of species combinations and sites.
Книги з теми "Pinus radiata Growth"
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Madgwick, H. A. I. Pinus radiata: Biomass, form and growth. Rotorua, N.Z: Madgwick, 1994.
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Workshop on Growing Radiata Pine from Cuttings (1986 Rotorua, N.Z.). Workshop on Growing Radiata Pine from Cuttings: Rotorua, 5-7 May 1986. Rotorua, N.Z: Ministry of Forestry, Forest Research Institute, 1988.
Знайти повний текст джерелаЧастини книг з теми "Pinus radiata Growth"
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Omil, Beatriz, Federico Sánchez-Rodríguez, and Agustin Merino. "Effects of Ash Applications on Soil Status, Nutrition, and Growth of Pinus radiata D. Don Plantations." In Recycling of Biomass Ashes, 69–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19354-5_6.
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Acosta-Hernández, Andrea Cecilia, Marín Pompa-García, Marcos González-Cásares, José Manuel Zúñiga-Vásquez, José Ciro Hernández-Díaz, José Rodolfo Goche-Telles, José Ángel Prieto-Ruíz, and Juan Abel Nájera-Luna. "How Drought Drives Seasonal Radial Growth in Pinus strobiformis from Northern Mexico." In Latin American Dendroecology, 21–36. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-36930-9_2.
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Sinkevich, Serguei M., and Markus Lindholm. "Short- and Long-Term Natural Trends of Scots Pine (Pinus sylvestris, L. ) Radial Growth in North- and Mid-Taiga Forests in Karelia." In Growth Trends in European Forests, 29–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-61178-0_4.
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Nöjd, Pekka. "Variation in radial growth of Scots pines exposed to heavy metal and sulphur emissions from the Cu-Ni smelter at Monchegorsk, NW Russia." In Forest Condition in a Changing Environment, 284–87. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-015-9373-1_34.
Повний текст джерелаТези доповідей конференцій з теми "Pinus radiata Growth"
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FREIMANE, Lāsma, and Mārtiņš AILTS. "RESPONSE REACTION OF SCOTS PINE PINUS SYLVESTRIS L. AFTER FOREST FIRE IN FOREST SITE TYPE HYLOCOMIOSA." In Rural Development 2015. Aleksandras Stulginskis University, 2015. http://dx.doi.org/10.15544/rd.2015.072.
Повний текст джерелаАнотація:
Many factors explain the importance of the research: role of forest industry in Latvian national economy, predicted climate changes in future that foresee better conditions for forest fires, and the fact that until this moment in Latvia there is very little research about radial growth dynamic after forest fire. Object of the research is surface fire affected middle-age managed Scots pine stands in forest site type Hylocomiosa. The empirical material was collected in 500 m2 large circular sample plots in both fire affected and fire unaffected parts of forest stands. At sample plots, dendrometric parameters of trees were measured. After low to medium intensity surface fire forest stand radial growth dynamics is positive, but effect of forest fire impact is negligible – in six year period six cubic meters per hectare or in average one cubic meter per hectare per year. Forest fire significantly does not affect mortality of trees in middle-age Scots pine forest stand in forest site type Hylocomiosa, p = 0.19 > α= 0.05. Minimal financial loss as result of deadwood volume after forest fire is 2179.00 EUR ha-1.
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Kabanov, A. N., and S. A. Kabanova. "DENDROCHRONOLOGICAL RESEARCHES IN ARTIFICIAL PLANTINGS OF NUR-SULTAN CITY." In STATE AND DEVELOPMENT PROSPECTS OF AGRIBUSINESS. DSTU-PRINT, 2020. http://dx.doi.org/10.23947/interagro.2020.1.564-566.
Повний текст джерелаАнотація:
Dendrochronological analysis was carried out in forest cultures of Pinus sylvestris of different ages growing in the green zone of Nur-Sultan city. It was found that the value of the annual radial growth is subject to a cycle with a period of 10-11 years. This is due to climatic conditions, in particular, with periods of solar insolation, which is confirmed by researches of other authors.
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Petro, Robert N., and Daejong Kim. "Parametric Studies on Dynamic Performance of Hydrostatic Flexure Pivot Tilting Pad Gas Bearing With Radial Compliance." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44354.
Повний текст джерелаАнотація:
Flexure pivot tilting pad gas bearings are recognized as an alternative to foil gas bearing [1, 2] for high speed turbomachinery, due to their capability to provide high rotor-bearing stability and simple structure. The flexure pivot design eliminates wear problem of axial pins or sockets at the pivots which are common in traditional tilting pad bearings. Added features such as a pivot offset and pad preloads can also be optimized to further improve the stability. Hybrid flexure pivot tilting pad gas bearing have also been reported [3]. The hybrid bearing has a direct air supply to the bearing clearance through a tiny orifice. It has shown that the hybrid operation of the tilting pad gas bearing can also increase the rotor-bearing stability [3]. In many microturbomachinery applications, hollow shafts are adopted to reduce the rotor weight and increase the bending critical speeds. However, the hollow shaft has a large centrifugal growth at high speeds requiring the gas bearing to have radial compliances. However, the radial compliance within the tilting pads can compromise the rotor-bearing stability because large displacement of the pads along the radial direction can cause hydrodynamic rotor-bearing instability associated with the increased bearing clearance (i.e. decreased effective preload) if the radial stiffness is not designed properly. Analytical studies show that optimal choice of pad radial stiffness could extend operating envelope of flexure pivot tilting pad gas bearing without deteriorating rotor-bearing stability [4]. High speed operation can generate significant amount of heat and adequate heat dissipation mechanism should also be developed. Hybrid operation is considered to have added benefit of effective cooling capability. This paper presents design studies on hybrid flexure tilting pad gas bearing with radial compliance which can accommodate large rotor centrifugal growth and also provide effective cooling mechanism.