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1.
Eight pieces of sapwood and heartwood from Scots pine, before and after linseed oil impregnation, were used to make 16 near-infrared hyperspectral images (90–200 pixels wide × 466–985 pixels long × 239 wavelengths: 982–2,480 nm). The wood pieces were selected according to a 2 × 2 experimental design using radial–tangential cut and heartwood–sapwood as factors with two replicates. A first mosaic of 16 images was cleaned and analyzed by image principal component analysis. Interpretation was realized by studying score images and score plots by brushing interaction. In the resulting T1–T2 score plot, the untreated pieces formed a dense cluster, while the impregnated ones showed larger variation. The good separation of treated and impregnated clusters was confirmed by PLSDA showing low false negatives and positives. Analysis of the eight impregnated wood pieces clearly showed regions of wrong impregnation in one wood piece. Loadings resembling linseed oil spectra indicated that this was due to badly polymerized linseed oil. After removing the outlier piece, a new model was made on the seven-piece mosaic showing in the T1–T2 score plot that heartwood and sapwood absorbed the linseed oil differently. This difference was not detected in the untreated wood, so it had to come from the impregnation process. Edges reacted differently from surfaces to the impregnation process as seen in the T1–T4 score plot. These findings show that a future online quality inspection of both raw wood and impregnated pieces would be feasible. 相似文献
2.
《Wood material science & engineering》2013,8(4):170-176
Abstract Eighteen sapwood and 18 heartwood samples from three Scots pine (Pinus sylvestris L.) trees were used to identify correlations between the features of their near-infrared spectra (400–2500 nm) measured before and after impregnation with linseed oil (Linogard®) and (1) the amount of oil taken up by the samples at three different longitudinal positions; and (2) the tissue type of sample. Calibration models were cross-validated and oil uptake models were also validated on separate test sets. Partial least squares regression models for the prediction of uptake and tissue type in non-impregnated wood were promisingly accurate, having coefficients of multiple determination (Q 2) values of > 0.8, 0.8 and 0.75 for predictions of tissue type, oil taken up as a percentage of sample mass and total mass of oil taken up, respectively. The models developed for linseed oil-impregnated samples were better still, generating Q 2 values of > 0.9, > 0.8 and 0.8 for the three key properties. In general, models based on spectra acquired along two directions of measurement (longitudinal and tangential) were more accurate than models based on only one. Tandem models consisting of two submodels, one for sapwood and one for heartwood, were more successful than single models applicable to both tissue types. 相似文献
3.
Two methods of sampling stemwood nutrients have been comparedon 10 Pinus pinaster (Ait.) trees: the increment borer method(non-destructive but producing samples which are not weighedaccording to the tissues' proportion) and the disc method (destructivebut producing weighed samples). The samples were divided intosapwood and heartwood, and nutrient concentrations were determinedfor major nutrients (N, P, K, Ca, Mg). Compared with the discsampling method, the increment borer sampling method significantlyunderestimated N, P and K concentration in sapwood, whereasit overestimated Ca and Mg concentration in heartwood. The meanerror ranged from –13 per cent (N and P in sapwood) to+14 per cent (Ca in heartwood). These results were in agreementwith previous studies which showed horizontal variations inthe nutrient concentration of stemwood. 相似文献
4.
《Wood material science & engineering》2013,8(3-4):135-142
Abstract The moisture sorption and swelling of spruce specimens impregnated with linseed oil and unimpregnated controls were studied in two sorption experiments: from 0 to 55% relative humidity (RH) and from 55% RH to water saturation. Sorption isotherms were also determined using a sorption balance. The impregnated specimens had lower rates of both moisture sorption and swelling than the unimpregnated controls; however, there was no significant difference in final moisture contents. In addition, the linseed oil impregnation did not improve the dimensional stability of the wood; in most cases the specimens impregnated with linseed oil swelled more than the unimpregnated controls. For the impregnated specimens, reductions in swelling rates were in most cases seen without corresponding reductions in final swelling. The moisture sorption rate was reduced for the impregnated specimens but there were generally no reductions in equilibrium moisture content. 相似文献
5.
《Wood material science & engineering》2013,8(2):139-144
Abstract The heartwood and sapwood from Scots pine (PS), Norway spruce (PA), and Oriental spruce (PO) were tested for susceptibility to discoloring fungi and water uptake. In addition, annual ring width and density were measured. The methods used were Mycologg for testing growth of fungi and a modified version of EN 927-5 to investigate water uptake. For pine, the heartwood showed a lower water uptake and no discoloring fungi growing in the tests. The heartwood had a significantly higher density and smaller annual ring width than the sapwood. In PA the heartwood had significantly lower discoloration than sapwood. The total water uptake in g/m2 was significantly higher in sapwood, but not the calculated moisture content. As for wood properties, the density was significantly higher in sapwood compared to heartwood, although there were no differences in annual ring width. Regarding PO, differences in water uptake could be seen between sapwood and heartwood although the densities were similar. These results show that susceptibility to discoloring fungi and water uptake is hard to correlate to a single inherent property when looking at different wood species. 相似文献
6.
The effect of geographical variation of planting rate on the uptake of carbon by new forests of Great Britain 总被引：1，自引：0，他引：1
The planting rates from 1921 to 1996 of new coniferous and broadleavedforests for 11 regions of Great Britain were assembled for thestate and private sectors. Over that period new planting totalled231 kha of conifers and 132 kha of broadleaves in England, 141kha of conifers and 16 kha of broadleaves in Wales and 881 khaof conifers and 52 kha of broadleaves in Scotland. These time series and regional values of Yield Class were usedas input data for an accounting model of carbon in the trees,litter, soils and products to produce estimates of their netuptake of carbon by the forests from the atmosphere (i.e. increasein the carbon pools). On the assumption that conifer and broadleafplanting could be represented by Sitka spruce and beech treesrespectively, litter and forest soil in Great Britain were accumulatingcarbon at 2.42 Mt a–1 in 1995–96. Coniferous forestaccounted for 89 per cent of this uptake. Scottish conifer andbroadleaf forests took up 68 per cent and mapping the uptakeshowed that the greatest rate occurred in western Scotland.The pool of carbon in wood products increased in 1995–96by 0.31 Mt a–1. The estimated uptake rates were sensitive to the relative amountsof conifer and broadleaf forest planted (particularly in relationto increases in the pool of carbon in wood products) but notto regional differences in Yield Class. Use of any single YieldClass in the range 10–16 m3 ha–1 a–1 for allSitka spruce planting produced estimates of uptake rate in GreatBritain to trees, litter and soil within ±10 per centof that, assuming yield varied across the country. Lack of preciseknowledge on the parameters of the model was estimated to introducean uncertainty of ±30–70 per cent into estimatesof carbon uptake. 相似文献
7.
The management of competing vegetation has evolved with forestmanagement over the past half century and is now an integralpart of modern forestry practice in many parts of the world.Vegetation management, primarily using herbicides, has provenespecially important in the establishment of high-yield forestplantations. There has been a substantial amount of researchquantifying the wood yield gains from the management of competingvegetation over the past few decades. We reviewed results from60 of the longest-term studies in North America (Canada andUS), South Africa, South America (Brazil) and New Zealand/Australia.About three-quarters of the studies reported 30–500 percent increases in wood volume from the most effective vegetationtreatments. In North America, where the longest-term studiesfor a variety of tree species were between 10 and 35 years old(or from 20–100 per cent of rotation age), gains in woodvolume ranged from 4–11 800 per cent in Pacific north-westernforests, 14–5840 per cent in the south-eastern forests,and 49–5478 per cent in northern forests. In South Africaand South America (Brazil), several full-rotation (6–8years) studies with eucalyptus indicate 29–122 per centand 10–179 per cent increases in wood volume yield, respectively,from effective vegetation management. In New Zealand, time gainsof 1 to 4 years from early vegetation control in radiata pineplantations translated into 7–27 per cent increases inwood volume yield over a 25- to 30-year rotation. 相似文献
8.
We examined the short-term effects of group-selection harvestingwith seed tree retention on the diversity, abundance and establishmentof tree seedlings in a northern hardwood forest in the UpperPeninsula of Michigan (49 openings, 20 closed canopy referencesites). Three opening sizes were examined – opening radius0.5 x canopy height (267 ± 62 m2, n = 16), 0.75 x canopyheight (642 ± 85 m2, n = 17) and 1.0 x canopy height(1192 ± 155 m2, n = 16) (canopy height = 22 m). A singleyellow birch (Betula alleghaniensis Britt.) seed tree was retainedin the centre of each opening. Tree seedling density was significantlyhigher in the largest group-selection opening than at the closedcanopy reference sites (P < 0.05), the main factor for thiswas the increased proportion of yellow birch, red maple (Acerrubrum L.) and other minor species. Nevertheless, yellow birchwas still a minor component of the developing gap cohort, comprising5.9 per cent of the seedlings and 1.1 per cent of the saplings.Within openings, microsite variables, such as per cent coversof bare soil and coarse woody debris, were the best predictorsof yellow birch occurrence and density. Our results suggestthat microsite limitations and competing vegetation may greatlyreduce the efficacy of openings for ensuring the maintenanceof mid-tolerants. 相似文献
9.
In an 11-year-old stand of Sitka spruce (Picea sitchensis [Bong.]Carr.) application of nitrogen fertilizers, at a rate of 10kgN ha–1 month–1, increased mean diameter incrementby 12 per cent, while the further addition of phosphorus, at5 kg ha–1 month–1, resulted in a 23 per cent increase.An attack by the green spruce aphid (Elatobium albietinum Walker)occurred during the period of fertilizer addition. The mostseverely affected trees showed a reduction in diameter growthof 50 to 56 per cent but the severity of the attack betweentrees was unrelated to the treatments applied. However, fertilizerapplication did hasten the recovery of diameter growth afterdefoliation. 相似文献
10.
The rate of accumulation of carbon in forests and woodlandsin Northern Ireland was estimated using the record of forestplanting since 1900 and a model that calculated the flow ofcarbon from the atmosphere to trees, litter, soil, wood productsand back to the atmosphere. It was assumed that all coniferforests had the carbon accumulation characteristics of Piceasitchensis, and upper and lower estimates of carbon storagewere calculated assuming Yield Class 16 m3ha–1 a–1unthinned and Yield Class 14 m3 ha–1 a–1 thinned.Broadleaved woodlands were assume to have the carbon accumulationcharacteristics of Fagus sylvatica, Yield Class 6 m3ha–1a–1. Northern Ireland currently has about 78 300 ha offorest, 83 per cent of which is coniferous, 77 per cent state-owned,mostly planted since 1945, with peak planting in 1960–1975.In 1990, conifer forests contained 3–4 MtC (trees + litter)and broadleaved wdlands contained about 0.8 MtC (trees + litter+ new forest soil). In 1990, conifer forests were sequestering0.15–0.20 MtC a–1 and broadleaved woodlands about0.025 MtC a–1. To maintain these sink sizes, new coniferforests need to be planted at 1500–2000 ha a–1,and new broadleaved woodland at100–150 ha a–1 inaddition to full restocking. Current carbon sequestration byNorthern Ireland forests represents around 6.5–8.2 percent of the total for UK forests and is greater per hectar thanin Britain because the average forest age is younger in NorthernIreland 相似文献
11.
Oyen Bernt-Havard; Blom Hans H.; Gjerde Ivar; Myking Tor; Saetersdal Magne; Thunes Karl H. 《Forestry》2006,79(3):319-329
Results from a literature review on pinewood ecology, silviculture,genetics, aspects of history and forest resources of Scots pine(Pinus sylvestris L.) in western Norway are presented. The pinewoodscover 40 per cent of the forested land, 0.31 million ha. Duringthe last 75 years, the area has increased by 17 per cent andthe growing stock has risen from 10 to 34 million m3. The impactof man in previous times was very marked, and has had a significantinfluence on the present forest conditions. The pronounced climaticgradients mixed with the topographic variation – fromthe coastal plains via the fjord systems to the high mountains– is reflected in rather steep gradients in the pine forestvegetation. Various floristic elements can be distinguished,from oceanic via the suboceanic in the outer islands to thethermophytic, boreonemoral and boreal elements in the innerfjord districts and valleys. The introduction of spruce (Piceaspp.) plantations on 10–15 per cent of former native pineforests has not negatively affected the bird fauna at the landscapescale. Although not particular species rich, the pine forestsharbour species usually not found in other forest types. Sofar, most work in the field of silviculture and forest ecologyin the pinewoods of West Norway has been in the form of casestudies. Implications of the results for forestry in the regionare briefly discussed. 相似文献
12.
In 1974–76 164 permanent 10x10 m plots were recorded atalternate intersections of a 100x100 m grid in Wytham Woods,Oxfordshire. Tree and shrub data were collected from all theplots in 1974–76, from 27 in 1984–85 and from allbut one in 1991–92. Changes in the structure and composition of the wood were assessedin terms of canopy cover, mean tree diameter, basal area andspecies occurrence. The wood has become more open (reduced canopycover) partly through management, partly through natural processessuch as windthrow and disease. The shrub cover has also declinedgreatly, probably because of increased deer browsing. Most standsare predominantly young growth and for the wood as a whole meantree diameter, basal area and tree height have increased. Theoverall composition of the wood has changed little, but therehas been a significant decline in mean woody species numberper plot from 5.8 to 4.1, mainly through declines in understoreyspecies and young oak (Quercus spp.). Elm (Ulmus spp.) coverhas been reduced by disease and birch (Betula spp.) sufferedpreferentially from windthrow. The results are used to indicate gains and losses in natureconservation terms for the wood as a whole. The strengths andweaknesses of this system may hold lessons for future woodlandmonitoring exercises. 相似文献
13.
Black heart is a non-fungal stain of ash (Fraxinus excelsiorL.) which results in a price penalty compared with white wood.The formation of black heart varies within individual trees,between trees and on different sites; the evidence availablesuggests that it can be present in up to 45 per cent of treesat age 60. Once formed the proportion of cross-sectional areaaffected increases with age. Previous work has suggested thatblack heart has no effect on timber properties or strength butits occurrence has been linked with high soil moisture. Howeverthese studies were conducted in the 1950s and need to be confirmedusing more rigorous research methods. Scope exists for innovativemarketing of black heartwood to emphasize that it is a naturalfeature and can be visually pleasing; this may lead to betterreturns for the grower. 相似文献
14.
Larvae of Agrotis segetum Schiff (cutworms) damaged seedlingson a light loam soil at Ken nington Nursery, Oxford. Experimentscarried out in 1955–7 investigated the effect of BHC,DDT, aldrin, and dieldrin on cutworms and their phytotoxicityto Sitka spruce (Picea sitcbensis) seedlings. A spray containing 3 lb. aldrin per acre (as a 30 per cent,miscible oil) or 1? lb. dieldrin per acre (as a 15 per cent,miscible oil) gave excellent control of Agrotis segetum larvaeand did no damage to the seedling crop. Both insecticides wereapplied in 100 gallons water per acre. Immediate control ofcutworm was obtained with applications at time of expected larvalemergence (mid-June) or at time of first visible crop damage(mid-July); applications one month later gave good control after3 days. Stock beds containing seedlings of all the conifers commonlyused in Britain have been sprayed in mid-July with aldrin anddieldrin at half the rate used in the experiments. No specieswas damaged and control of cutworm was good. 相似文献
15.
Samples of LFH collected beneath the canopies of 16 coniferousspecies growing at the same site were incubated in the laboratorywith or without a starch amendment. Exchangeable nitrogen presentranged from 10.5–256 and 11.4–512 µgg–1organic matter for freshly collected and unamended incubationsrespectively. When starch was added material from 11 speciesshowed significantly greater accumulation of mineral nitrogenwith increases ranging from ca 20–1370 per cent. Nitrificationwas negligible except in Thuja plicata where nitrate constituted68 or 83 per cent of the mineral nitrogen present after incubationwithout or with starch respectively. Starch addition increasedrates of net nitrogen mineralisation in LFH material from Piceasitchensis over a range of growth rates. Rates were greatestin material from the most productive stands whether or not starchwas added. The results are discussed with reference to the factorscontrolling litter decomposition and nitrogen mineralisationin the forest floor. 相似文献
16.
Between 1987 and 1991 four surveys on the condition of forestsin Tuscany (Central Italy) were carried out. The results, relatingto 2275 trees in 111 sampling plots, show that the overall percentageof damaged trees (defined by the EC regulation 1696/87) increasedbetween 1987–88 (51.4±5.4 per cent; 54.0±5.6per cent) and 1990–91 (67.0±6.2 per cent; 64.0±6.1per cent). The percentage of moderately and severely damagedtrees also displayed an upward trend. The most severely affectedspecies appeared to be Pinus pinea (a Mediterranean conifer,96.7 per cent damaged trees) and Fagus sylvatica (a mountainbroadleaf, 87.1 per cent damaged trees). Crown condition appearedto deteriorate with decreases in mean annual rainfall and wherestand conditions are poor (thin soil, steep slopes). The findingssuggest the possibility of an interaction between several differentstress factors, some of which seem to be linked to local andstand conditions (exposure, silviculture, soil fertility), whileothers seem to be connected with long-term variations, suchas changes in environmental parameters like precipitation. Theactual role of background and/or local pollution can be neitherdemonstrated nor excluded on the basis of the present results. 相似文献
17.
Interception loss was measured indirectly for 3 years in adjacentunthinned 25-year-old stands of Sitka spruce and lodgepole pineand for 2 years in a 63-year-old selectively thinned stand ofSitka spruce. For each stand measurements were made of grossprecipitation, throughfall and stemflow. Interception loss wasderived by subtracting the sum of throughfall and stemflow (netprecipitation) from gross precipitation. For the years 1977–78, 1978–79 and 1979–80,interception losses in the pole-stage Sitka spruce were 32,28 and 27 per cent of gross precipitation respectively whilethose in the lodgepole pine were 33, 29 and 26 per cent. For1979–80 and 1980–81 interception losses in the matureSitka spruce were 44 and 53 per cent of gross precipitation.The average interception loss was 29 per cent for both pole-stagecrops and 49 per cent for mature Sitka spruce. The proportions of net precipitation reaching the ground asstemflow and throughfall were 0.18 and 0.82 respectively forthe pole-stage Sitka spruce, 0.14 and 0.86 for the pole-stagelodepole pine and 0.02 and 0.98 for the mature Sitka spruce. 相似文献
18.
Changes in susceptibility to wind and snow damage due to thinningand fertilization were examined in even aged Norway spruce (Piceaabies (L.) Karst.) stands in southern Sweden. The stands arepart of a nationwide experiment to investigate growth and yieldfollowing different thinning and fertilization regimes establishedbetween 1966 and 1983. The material used in this study included16 replications of seven treatments. The treatments were: threelevels of thinning from below (20–70 per cent); 20 percent thinning from above; thinning from below in combinationwith N and NP fertilization (thinning percentage 25–28per cent); and unthinned control. The stands have been censusedtwice for damage during an average period of 12 years. The degree of wind and snow induced damage varied between 9and 20 per cent of the basal area increment produced duringthe observation period. For treatments with high basal arearemoval, the highest relative number of trees damaged by windoccured during the first period after thinning. The denseststands (i.e. unthinned controls and stands thinned from above)showed a high proportion of snow damage throughout the observationperiod. The block effect was in general more significant thanthe effect of treatments on damage level. When analysing theinfluence of the block effect (i.e. of site and stand characteristics)on damage level, wind damage was best predicted by stand basalarea left after thinning and stand age, while snow damage wasbest predicted by latitude, altitude, site index, and standage. On average the tested site and stand characteristics explained17 per cent of the variation in wind damage and 36 per centin snow damage. 相似文献
19.
Sanni Raiskila Kurt Fagerstedt Tapio Laakso Pekka Saranpää Mia Löija Leena Paajanen Riitta Mahlberg Anne-Christine Ritschkoff 《Wood Science and Technology》2006,40(8):697-707
It is known that active peroxidase isozymes exist in mature wood of Norway spruce (Picea abies L. Karst.) and that they remain active for years and are found even in the heartwood (in Scots pine), where all cellular activity has ceased. This peroxidase activity was utilised in the impregnation of wood blocks with a natural monolignol, coniferyl alcohol and hydrogen peroxide. The hypothesis was that the internal wood peroxidases would oxidise the added monolignol and bind it stably into the cell wall matrix, which could hinder fungal decay. Since coniferyl alcohol is not very soluble in water, the impregnation was done under vacuum with an acetone–water solution containing 10% coniferyl alcohol and 0.4 mM H2O2 at room temperature (ca. 0.02 g of coniferyl alcohol was added to 1 g of wood). After impregnation, dimers of coniferyl alcohol and free coniferyl alcohol were found in acetone extracts with GC–MS analysis. Penetration of coniferyl alcohol and non-extractable reaction products were studied from the wood blocks with FTIR PAS technique. The wood samples treated were also subjected to a fungal decay test with Coriolus versicolor. This treatment hindered fungal decay in a 60-day experiment and led to a dry weight loss of 8.8% in comparison with 19.9% in the control. The reactions of coniferyl alcohol and H2O2 in the presence of peroxidases are discussed as well as the use of monolignols to increase wood decay resistance. 相似文献
20.
A Cupressus lusitanica spacing experiment located at Rongai,Northern Tanzania was assessed at the age of 19 years. The experimentwas planted at square spacings of 1.13 m, 1.46 m, 1.88 m, 2.43m, and 3.14 m. Other than pruning to 1.8–2.0 m at theage of 3 years and routine weeding, the experiment did not receiveany other treatment. Assessment was made of survival, branchdiameter, height, basal area, volume production, heartwood content,basic density and wood strength. Height, basal area, merchantablevolume, basic density, heartwood content, modulus of elasticity,modulus of rupture and compression parallel to grain were notsignificantly affected by spacing. All other variables weresignificantly affected. Mortality decreased with increasingspacing while branch diameter and breast height diameter increased.Total volume decreased with increased spacing. The implicationsof these results on future management of C. lusitanica in Tanzaniaare discussed. 相似文献