Showing papers on "Pinus radiata published in 2005"

Is Pinus radiata invading the native vegetation in central Chile? Demographic responses in a fragmented forest

Abstract: Forest fragmentation facilitates the invasion of exotic species. This threat may be especially severe if forest fragments are surrounded by plantations of exotic species like Pinus radiata, an aggressive colonizer and shade-intolerant tree that has invaded successfully several native ecosystems of the southern hemisphere. In this study, we experimentally tested if the conditions of a successful seedling establishment P. radiata are fulfilled at the Coastal Maulino forest, an endemic fragmented forest of central Chile. Results demonstrated that seeds are dispersed into the native forests, however seedling establishment occurs only at the edges. We conclude that this exotic species is not invading native forests up to date. However, we suggest to conduct evaluations of seed rain and seedling establishment in the long term, in order to monitor the fate of this exotic species in fragmented native forest of Central Chile.

Nucleotide variation in genes involved in wood formation in two pine species

Abstract: Summary • Nucleotide diversity in eight genes related to wood formation was investigated in two pine species, Pinus pinaster and P. radiata. • The nucleotide diversity patterns observed and their properties were compared between the two species according to the specific characteristics of the samples analysed. • A lower diversity was observed in P. radiata compared with P. pinaster. In particular, for two genes (Pp1, a glycin-rich protein homolog and CesA3, a cellulose synthase) the magnitude of the reduction of diversity potentially indicates the action of nonneutral factors. For both, particular patterns of nucleotide diversity were observed in P. pinaster (high genetic differentiation for Pp1 and close to zero differentiation associated with positive Tajima's D-value for CesA3). In addition, KORRIGAN, a gene involved in cellulose–hemicellulose assembly, demonstrated a negative Tajima's D-value in P. radiata accompanied by a high genetic differentiation in P. pinaster. • The consistency of the results obtained at the nucleotide level, together with the physiological roles of the genes analysed, indicate their potential susceptibility to artificial and/or natural selection.

Efficiency of early selection for rotation-aged growth and wood density traits in Pinus radiata

Abstract: A total of 1097 cross-sectional wood disks from breast height were sampled from two rotation-aged (27 and 31 years from planting) genetic trials of radiata pine (Pinus radiata D. Don) in Australia to estimate the genetic correlation between early and rotation-aged growth and wood quality traits and the efficiency of early selection. Annual growth-ring width and density, diameter at breast height (DBH), and area-weighted density (AD) from 30 open-pollinated families were measured using X-ray densitometry. Genotype × site interactions were not significant for density and growth traits. Ring density increased steadily from the pith to cambial age 14, and then density had little change in the following years. For AD, the family and individual heritability estimates were about 0.60 and 0.30 after the first 2 years. For DBH, family and individual narrow-sense heritability estimates increased steadily after the first 4 years, and family heritability increased to 0.7 at a cambial age of 11 and had little change t...

Fine root production and litter input: Its effects on soil carbon

Abstract: Carbon storage by forests has potential for contributing to ‘Kyoto Protocol’ greenhouse gas emission reduction targets, but evidence about C-storage and loss below ground is conflicting. The study addresses why soil carbon stocks are increased by land use change from forest to pasture, but are reduced by planting conifer trees, though not broadleaf trees, onto prior pasture. Can species differences in fine root production and litter input play a role? Addressing that hypothesis, a 1-year pot experiment was established as a model system in a glasshouse. Two tree species, pine (Pinus radiata) and Blue Gum (Eucalyptus globulus), and two grass species, Kangaroo Grass (Themeda triandra) and Wallaby Grass (Austrodanthonia racemosa), were sown in pots of soil taken from a native pasture with Kangaroo Grass dominant or from an adjacent pine plantation forest. After 3 months, half of the grass pots were defoliated monthly to 7 cm above ground to test for any cutting effect. Fine root production and turnover was monitored via minirhizotrons, with a destructive harvest after 1 year. Fine root oven dry mass at the end of the year varied between species: Kangaroo Grass (17 g/pot), pine (13 g/pot), Blue Gum (8 g/pot), Wallaby Grass (4 g/pot). Cutting significantly reduced fine root production in Kangaroo Grass but not in Wallaby Grass. From minirhizotron monitoring, 70% of the fine root length produced by pine during the year had disappeared, presumably by decomposition, before the final harvest. The equivalent loss for Wallaby Grass was only 26%, for Kangaroo Grass 36%, and for Blue Gum 45%. Despite the faster fine root disappearance under pines than under Kangaroo Grass, soil C declined under pines but increased under Kangaroo Grass as found in the field. Thus the experiment did not support the idea that a lower dead fine root production was the source of decline in soil C under pine. There was only a weak correlation between soil C change and the net amount of live fine root mass produced. However, the soil carbon changes in this study were positively correlated with live fine root length density in the soil. Kangaroo Grass maintained large lengths of very fine roots while pines produced a small length of thick fine roots. Accordingly, it is hypothesized that the increase of soil carbon under Kangaroo Grass compared with pine may be caused more by the activity of live fine roots than by decomposition of fine root mass to humus. This hypothesis, formulated from the model experimental system, needs to be evaluated for field sites where pines have been planted onto pastures.

Survey of potential sapstain fungi on Pinus radiata in New Zealand

Abstract: A nationwide survey of New Zealand sap- stain fungi on Pinus radiata was undertaken between 1996 and 1998 with collections of 1958 samples of material from 869 sites in the North and South Is- lands. Material was collected from mills, ports, forest plantations of native, exotic, or P. radiata, nurseries, farms, and urban areas. Material collected included branches, twigs, needles or leaves, cones, logs, wood chips, timber, and veneer. From these collections, 2154 potential sapstain fungi, representing 14 known species plus a number of unidentified species, were isolated. The predominant sapstain fungi isolated were Sphaeropsis sapinea, Ophiostoma ips, O. floc- cosum, O. piliferum, Leptographium procerum, and O. querci. S. sapinea was isolated from all material sampled including collections from the forest floor (including branches, twigs, needles, leaves, cones, and logs) as well as from logs and timber. In contrast Ophiostoma species were mainly found on logs, timber, and wood chips.

Wood properties of juvenile Pinus radiata growing in the presence and absence of competing understorey vegetation at a dryland site

Abstract: Pinus radiata D. Don trees were grown in the presence and absence of the woody weed broom (Cytisus scoparius L.) on a dryland site for 2 years to determine the effects of competition from weeds on wood properties in juvenile trees. Wood property measurements made on cross-sections from the bark to the pith were scaled to convert results from distance to a time basis using sigmoidal equations fitted to monthly measurements of tree diameter. When averaged across the 2 years, the presence of the weeds significantly increased wood density (+11%), wall thickness (+6%) and modulus of elasticity (MOESS, +93%), and significantly reduced microfibril angle (MFA, −21%) and radial diameter (−8%). Radial growth rate was significantly correlated to wood density, and this relationship held across both treatment and age. At the seasonal scale, there was close correspondence between changes in MFA and growth rate. Ring width was significantly related to both MFA and MOESS at the annual scale. Although both of these relationships held across treatments, year significantly influenced the value of coefficients in the relationships. The results highlight the direct effects of the presence of weeds on wood properties and the need to consider silvicultural treatments appropriate for balancing gains in productivity with losses in wood quality for timber production.

Gradient analysis of exotic Pinus radiata plantations and potential restoration of natural vegetation in Tenerife, Canary Islands (Spain)

Abstract: Afforestation on the island of Tenerife has been carried out mainly with the native species of pine Pinus canariensis Chr. Sm. Ex DC. However, the exotic pine Pinus radiata D. Don has been introduced in some areas. Several studies have shown that plantations of exotic species facilitate forest succession in their understories on sites where disturbances prevent the recolonization by native forest species. We randomly located 250 plots in stands of P . radiata , on the island of Tenerife and recorded species. Abiotic characteristics of the plots were also noted. We evaluated the regeneration of potential vegetation of the laurel forest and pine forest under a canopy of an exotic pine species. Analysis of the species composition, resulted in four well defined groups: advanced laurel forest group (ALF), undeveloped laurel forest group (ULF), ruderal group (RU) and Canarian pine stand group (CPS). These groups can also be discriminated base on altitude, slope or canopy cover. For ALF and ULF we propose thinning restoration management and the planting of new individuals of laurel forest species. For RU and CPS, because they are potentially P . canariensis stands, we propose continuous elimination of P . radiata and enrichment with new individuals of P . canariensis .

Comparative in vitro and early nursery performance of adventitious shoots from cryopreserved cotyledons and axillary shoots from epicotyls of the same zygotic embryo of control-pollinated Pinus radiata

Abstract: This is the first published report comparing production and performance of adventitious shoots from cryopreserved cotyledons, with axillary shoots formed from epicotyls of the same zygotic embryo of radiata pine (Pinus radiata D. Don). Genotypes from 10 control-pollinated families of P. radiata in two treatments were compared for shoot initiation, in vitro growth, rooting, and early nursery performance. Plant growth in nursery beds was assessed by measuring height after 2 and 7 months. After 8 months in nursery beds, the physiological ages of genotypes were assessed before field planting. Genotype capture was higher from the cryopreserved cotyledons than from the epicotyls. This technique has the advantage of preserving juvenile material while field testing is done. Early shoot multiplication in both treatments was good. After four transfer cycles, epicotyl cultures showed improved elongation and higher multiplication rates. After 6 months of in vitro growth, shoots from both treatments were given auxin p...

Effects of mixing radiata pine needles and understory litters on decomposition and nutrients release

Abstract: A microcosm experiment was conducted to understand the impacts of mixing radiata pine (Pinus radiata D. Don) needle litter and understory (gorse—Ulex europaeus L., broom—Cytisus scoparius L., bracken—Pteridium aquilinum L., and lotus—Lotus pedunculatus L.) litter materials on decomposition and nutrient release dynamics. Mixing of pine needle litter with understory litter material had significant impacts on both the rate of decomposition and nutrient release patterns of pine litter as well as that of the understory species. Incubation in microcosms over 10 months resulted in significantly lower mass loss of radiata pine needle litter mixed with broom and lotus litters (35.8±8.4 and 41.3±0.8%, respectively) than pure pine needle litter (63.5±2.3%). Mixing with pine needle litter significantly increased the mass loss of broom (53.1±6.1%) compared to that of pure broom (30.2±1.0%). Significant transfers of nutrients, especially of magnesium and potassium, were observed in litter mixture treatments. Concentration of K in litter materials was found to be the most limiting factor for the decomposing microorganisms in the present study. The findings of this study suggest that management of understory litter composition via weed control could be used to manipulate carbon turnover and nutrient release in the forest floor. Also, initial selection of understory species will be important and could be managed.

Influence of Ectomycorrhizal Hyphae on Phosphate Fractions and Dissolution of Phosphate Rock in Rhizosphere Soils of Pinus radiata

Abstract: A study was conducted to determine the effect of ectomycorrhizal hyphae on phosphate rock dissolution and soil properties in the rhizosphere of one-year-old Pinus radiata D. Don seedlings established on an allophanic soil (Andosol) in the field. High and low ectomycorrhizal hyphal activities were produced in soils inside the lower compartments of rhizosphere study containers by using either 26 μm or < 10 μ m pore-size nylon mesh(es) at the interfaces between the lower and upper compartments. The meshes at the interfaces allowed (26 μm) or reduced (< 10 μ m) hyphae penetration into the lower compartment. Pairs of containers, one with 26 μ m mesh and the other with < 10 μ m mesh, were buried under Pinus radiata seedlings for 10 months in a forest plantation. The effect of ectomycorrhizal (ECM) hyphal activity on phosphate rock dissolution and soil properties was determined. The increased ECM hyphal activity induced increased soil acidification and promoted greater production of acid phosphatase enz...

Moisture-Related Distortion of Timber Boards of Radiata Pine : Comparison with Norway Spruce

Abstract: Based on material data obtained by several researchers at Forest Research in New Zealand, with respect to variations in the main material properties from pith to bark, the distortion model developed earlier for Norway spruce has been further modified for radiata pine. Numerical simulations were performed for both pine and spruce to investigate how different sawn pattern options affect the shape stability of individual boards. Results for spruce presented earlier have shown clearly that warping of the timber products is strongly influenced by the annual ring patterns within the individual boards. Comparisons between the two species were performed to study how the radial variations in the basic properties such as shrinkage parameters, stiffness parameters, and spiral grain have influence on the warping. Generally, the intrinsic patterns of variation in wood properties within stems were similar, and both species show a tendency to distort with changing moisture environment. There are strong indications that intelligent re-combination of material in glued products may overcome many of the inherent problems in using biological material with predictable variation in material properties.

Infection of radiata and bishop pine by Mycosphaerella pini in California

Abstract: Infection of radiata pine (Pinus radiata D. Don) and bishop pine (Pinus muricata D. Don) by Myco sphaerella pini Rostr. in Munk was determined on needles of infected forest trees in central to northern coastal California. Conidia from infected trees were used to inoculate radiata pine seedlings maintained in constant and (or) fluctuating moisture and temperature regimes. On needles of radiata pine but not bishop pine plantation trees, most conidial germ tubes grew directly towards and entered the nearest epistomatal opening. On inoculated radiata pine seedlings in infection chambers, germ tubes grew haphazardly and few entered openings. Germ tubes entered epistomatal openings more often on abaxial than adaxial needle surfaces of both plantation trees and inoculated seedlings, and more lesions developed on the abaxial surface. Simple hyphae penetrated through epistomatal chambers, between guard cells, and into substomatal chambers. On radiata pine plantation trees, germ tubes that penetrated below guard ce...

Managing plantation forests to provide short- to long-term supplies of wood to streams: a simulation study using New Zealand's pine plantations.

Abstract: Riparian functions such as the recruitment of wood to streams take decades to recover after a clear-fell harvest to the stream edge. The implications of two sets of riparian management scenarios on the short- and long-term recruitment of wood to a hypothetical stream (central North Island, New Zealand) were compared through simulation modeling. In the first set (native forest buffer), a designated treeless riparian buffer was colonized by native forest species after a pine crop (Pinus radiata) had been harvested to the stream bank. In the second set (pine to native forest buffer), native forest species were allowed to establish under the pine canopy in a designated riparian buffer. In general, the volume of wood was greater in streams with wider buffers (5-m to 50-m) and this effect increased with forest age (800 years). The pine to native forest buffer supplied more wood to the stream more quickly, and matched the long-term supply to the stream from the native forest buffer. For the native forest buffer, total wood volume was minimal for the first 70 years and then increased uniformly for the remainder of the simulation. In contrast, the pine to native forest buffer produced a bimodal response in total wood volume with the initial sharp peak at year 100 attributed to pine recruitment and a second more gradual peak lasting for the rest of the simulation, which was similar to levels in the native forest simulations. These results suggest that existing plantations could be an important source of wood to the stream during the first 100+ years of native forest development.

Short term effects of radiata pine and selected pasture species on soil organic phosphorus mineralisation

Abstract: Silvopastoral systems comprise part of the continued expansion of conifer plantings on grassland in New Zealand. Greater understanding of the short term dynamics of soil organic P in such systems will further our knowledge about soil carbon and phosphorus relationships which will enable improved nutrient management in the field. A glasshouse experiment was carried out to examine the short-term effects (36 weeks) of combinations of radiata pine (Pinus radiata), lucerne (Medicago sativa L.) and perennial ryegrass (Lolium perenne L.) grown in the same soil type with a range of carbon (C) and phosphorus (P) levels on plant P uptake and the specific mineralisation rate (SMR). The SMR is defined as net mineralisation rate (i.e. gross mineralisation less microbial and geochemical uptake) and calculated from organic P decline as a percentage of organic P in the original soil before planting. This included an investigation of the effect of tree ectomycorrhizal (EM) hyphae on soil organic P. Plant P uptake was positively correlated with water soluble organic carbon (WSOC) and SMR, which in turn was closely related to soil C levels. The soils with high WSOC and C levels (which also contained high levels of labile inorganic and organic P) enabled high P uptake. Although P uptake was the greatest under radiata pine, the trees tended to deplete inorganic P to a lesser extent than the forages. When tree and forage species were combined, P uptake by forages was similar to when the forages were grown alone. The various soil and plant treatments significantly affected SMR. The two low C soils, showed the greatest organic P mineralisation while a high C soil, which contained significant levels of bicarbonate extracted inorganic P at planting and was under a long established undisturbed pasture, showed the least mineralisation. Trees grown alone showed the greatest SMR, EM hyphae and trees with lucerne were slightly lower than trees alone, while the forages showed the lowest SMR. The findings of this study showed that changes in organic P are strongly influenced by interactions between plant species (radiata pine, lucerne, ryegrass) and soil properties as determined by land use and management.

Effect of cold storage treatments and transplanting stress on gas exchange, chlorophyll fluorescence and survival under water limiting conditions of Pinus radiata stock-types

Abstract: The capacity of radiata pine seedlings to overcome planting shock in wet and dry conditions and their dependence on previous history was analysed by studying post-planting resumption of gas exchange and photochemical reactions, and survival 2 months later. Even under well-irrigated soil conditions, seedlings showed the effects of stress: gas exchange was reduced, but a clear difference between soil-plugged (PR) seedlings and bare-root (BR) seedlings was observed. Drought enhanced the severity of photosynthesis deprivation. Photochemical reactions, analysed by chlorophyll a fluorescence parameters, were not affected by planting shock in conditions of available soil water, but altered dramatically when drought stress was raised, suggesting structural damage of photosynthetic machinery. Despite the dramatic sensitivity of radiata pine to water availability, rewatering produced remarkable recovery, indicating good photosynthetic components repair capacity, which depended, however, on stock quality at the moment of planting. The ability of radiata pine to cope with drought in terms of post-planting performance depended on both storage conditions and water availability at the planting site. These findings provide information for tree physiologists and foresters as to how the management of radiata pine seedlings before planting can affect post-planting performance potential under wet or dry environmental conditions.

Fibre Length, Microfibril Angle and Wood Colour Variation and Interrelationships for Two Radiata Pine Trees with Mild and Severe Compression Wood

Abstract: Growth-layer-level radial, circumferential and height variation in fibre length, a selected wood colour parameter (L*) and microfibril angle (MFA) were determined for a nominally straight and a severely bent radiata pine. The 16-year-old trees were ramets of the same genotype grown on the same site. Visual compression wood was rated as being absent to mild in the straight tree, and being absent to severe in the bent tree. Growth-layer-level patterns of change with stem height and radial direction are strongly matched (particularly for the benttree) for fibre length, L* and MFA; with increasing compression wood contents giving progressively shorter fibres, and lower L* (darker) and higher MFA values. Correlation between the length, L* and MFA property-residuals is weak to moderate for the control-tree, and moderate to strong for the bent-tree.

Native species dominate the millipede fauna in a second-rotation Pinus radiata plantation in Tasmania, Australia

Abstract: Soil-dwelling millipedes were methodically hand-sampled in two second-rotation Pinus radiata stands in Stoodley Plantation in north-central Tasmania. Eleven of 14 species collected were natives, and native millipedes comprised 83% of the 1 456 identified specimens. The average millipede catch in 40 x 0.5 m2 quadrats was 74 individuals/m2. All nine of the native species of Chordeumatida, Polydesmida and Polyzoniida found in the survey had previously been collected in native forest within a 10 km radius of the pine plantation. Historical records indicate that Stoodley Plantation was established on abandoned farmland, and the two sampled areas have carried P. radiata for at least 60 years. The survey results support the suggestion that plantation development on cleared farmland can assist in local-scale conservation of native invertebrates.

Environmental Constraints on Growth Phenology, Leaf Area Display, and Above and Belowground Biomass Accumulation of Pinus radiata (D. Don) in Chile

Abstract: RUBILAR, RAFAEL ALEJANDRO. Environmental constraints on growth phenology, leaf area display, and above and belowground biomass accumulation of Pinus radiata (D. Don) in Chile. (Under the direction of H. Lee Allen). 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 mhayear to 6.8 mhayear 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. ENVIRONMENTAL CONSTRAINTS ON GROWTH PHENOLOGY, LEAF AREA DISPLAY, AND ABOVE AND BELOWGROUND BIOMASS ACCUMULATION OF Pinus radiata (D. Don) IN CHILE

Análisis de biomasa del vuelo de un rodal adulto de Pinus radiata Analysis of aboveground biomass in a mature stand of Pinus radiata

Abstract: SUMMARY A study of biomass in Pinus radiata D. Don with 42 years old was made, the trees were obtained of a stand placed between the cities of Santa Juana and Nacimiento, VIII Region, Chile. Three classes of top were differentiated in the stand: dominant, codominant and intermediate. The value of the mass for each component (wood, bark, branches, branchlets and needle) was obtained from each class of top; the wood resulted as the most important component in the total biomass of the tree (88.9%), then the bark (8.2%) and branches (1.5%). Obtained the values of biomass, the function of biomass for each component was obtained, related this values with the variables of the tree; the variables that showed greater correlation with the values of biomass by component and minors estimation errors are dbh (breast height diameter) and dbc (base of live crown diameter).

Nitrogen volatilisation from urea fertiliser in mid-rotation Pinus radiata plantations in south-eastern Australia

Abstract: Summary Because of its perceived cost advantage, most N fertiliser applied to mid-rotation Pinus radiata in Australia is in the form of urea. However, the potential for large N-volatilisation losses from urea may reduce its cost-effectiveness, and result in significant over-estimation of expected growth responses. The volatilisation loss of N from urea was compared with that from ammonium sulphate at two sites in radiata pine plantations aged 17 and 27 y, using a mass balance method in which 15N enriched fertiliser (200 kg N ha−1) was applied to microplots. Rainfall was excluded from the plots, but deionised water was added periodically, equivalent to a total of 12 mm over 28 days. Recovery of N from each fertiliser form was determined at 1, 7, 14 and 28 days. After 28 days, 41% of the N applied as urea (equivalent to 83 kg N ha−1) had been volatilised, compared with no significant N loss from ammonium sulphate. Significantly, 76% of the total loss of N from urea occurred during the first week. There was ...

Research on biomass and productivity of Pinus radiata plantations

Abstract: A preliminary research was conducted on biomass and productivity of five years old Pinus radiata plantations in the arid river valley areas of the upper reaches of the Minjiang River,and methods of "average stand tree" and "quadrat yield" were used for the investigation of the biomass of arbor,bush,herb,moss and litter layers.The following regression equations were divided from the standing crop of the destructive trees:W_t=3.03201(D~2H)~(0.87732)W_(br)=2.15635(D~2H)~(0.95504)W_1=3.24511(D~2H)~(0.87984)W_(ba)=2.23432(D~2H)~(0.75703)W_r=2.39599(D~2H)~(0.82747)Wu=4.12304(D~2H)~(0.88809)W_a=4.89706(D~2H)~(0.8848).The precision of the equation is over 97%,and the net yield and the yield structure were also studied.the estimated total biomass of the Pinus radiata plantation is 19.507 t/hm~2,and the productivity is 3 902.40 kg/(hm~2·a).The arbor-layer biomass is 8.510 t/hm~2,and its' productivity is 1 702.00 kg/(hm~2·a),occupying 43.62% of the total stand.The biomass and productivity of shrub,herb,moss and litter layers are 2.171 t/hm~2?434.20 kg/(hm~2·a),8.091 t/hm~2?1 618.20 kg/(hm~2·a),0.464 t/hm~2?92.80 kg/(hm~2·a) and 0.271 t/hm~2?54.20 kg/(hm~2·a),respectively.The biomass and productivity of Pinus radiata plantations are more higher than those of Pinus tabulaeformis and Cupressus chengiana plantations.

Experiments with the Introduction and Cultivation of Pinus radiata D.Don in the Upper Reaches of the Minjiang River,Sichuan Province,China

Abstract: Experiments with introduction and afforestation of Pinus radiata DDon were conducted for 14 successive yearsThe following results have been drawn from experiments and researches that(1) the survival and preservation ratios of the plantation planted with rocks or plastic membranes covering in combination with site preparation of level trenches and 15 m×2 m of planting density were 96% and 90% respectively;(2)By contrast,Pinus radiata plantations which were six years old through tending were averagely 202 times higher than the control,and the ground diameters of the former were 209 times more than the latter;when the quantity of fertilizer applied to a sapling of Pinus radiata was 20g(N)+100 g(P),Pinus radiata trees were 657 cm～1202 cm higher than the control and the ground diameters of the former were 174 cm～383 cm thicker than the latter;Pinus radiata trees through 1/3 cutting branches were 2957 cm higher and 30 cm thicker than the control and through 1/4 cutting branches were 1981 cm higher and 254 cm thicker than the control;(3)Pinus radiata trees have two height growth peaks and three ground diameter growth peaks in a yearThe periods of faster growth of their height and ground diameter appeared at the age of 4 to 6 and the biomasses of their roots,branches and leaves were sharply increased at the age of five