尾巨桉无性系不同造林措施林分生长调查

以尾巨桉(Eucalyptus urophylla×E.grandis)无性系为造林品系,设计了5种不同造林密度和6种不同施肥组合进行造林示范,对43个月生不同造林措施示范林生长量进行分析。结果表明,尾巨桉无性系林分树高、胸径、单株材积生长量随林分密度的增加而减小,但林分蓄积量则有随林分密度的增加而增大趋势,最高密度的林分蓄积量最大,达129.28 m3/hm2;造林后追肥可明显促进林木生长,追肥的林分蓄积生长量是不追肥的166.7%,并且以追肥用量大的林木生长效果更好;在造林后1个月及时追肥情况下,可选用磷肥或复合肥作基肥。     

Optimal planting times for freshly lifted bare-rooted conifers on the North York Moors

Two-year-old Picea sitchensis (Queen Charlotte Islands and Oregonprovenances), Pseudotsuga menziesii, Larix kaempferi, Larixeurolepis, Pinus sylvestris and Pinus nigra var. maritima werelifted at intervals during two winters and planted within 24h on a nearby second rotation site. Physiological conditionat planting, measured by root growth potential and fine rootelectrolyte leakage, and outplanting performance were significantlyinfluenced by lifting date. There were consistent differencesin the species' response to lifting date. Planting out in Septemberresulted in poor survival. Survival of P. sitchensis liftedin October until April was >90 per cent. Pinus sylvestrisand P. nigra had survivals of >90 per cent when lifted inNovember and January respectively until March. There was noclear pattern in P. menziesii performance. Both L. kaempferiand L. eurolepis had two periods of good survival—Octoberand March—with significantly poorer survival and growthassociated with mid-winter planting. The double peak in larchperformance was closely related to root growth potential; lowmid-winter establishment was associated with root growth potentialsof <5 even though the nursery root systems were in excellentcondition as assessed by electrolyte leakage.     

Establishment and Provenance of Walnut in Britain

This article reviews the silviculture of walnut in Britain andconsiders the case for planting common walnut (Juglans regia)or black walnut (Juglans nigra), neither of which is nativeto Britain. In addition the results of four provenance experimentsplanted in southern Britain in 1986–87 are described.The results of the experiments confirm that walnut is extremelysensitive to site conditions and should only be planted on themost suitable frost free, fertile, well drained and deeply rootablesites. Species comparisons show that J nigra is more tolerantof poor sites than J. regia, but at the only suitable site forplanting walnut there was little difference between the twospecies. Vermont, Ohio and Illinois provenances of J. nigraall performed well on the best site in the Chilterns and relativelywell on the other poorer sites.     

The carbon sink provided by plantation forests and their products in Britain

The rate of accumulation of carbon in forest plantations inBritain is estimated using the record of forest planting since1925 and a model that calculates the flow of carbon from theatmosphere to trees, litter, soil, wood products and back tothe atmosphere. It is assumed that all trees planted so farhave the carbon accumulation characteristics of P. sitchensis,Yield Class 14 m³ ha^-1 a^-1, but that future planting could includeF. sylvatica Yield Class 6 and Populus Yield Class 12. It isfurther assumed that conifer plantings increase surface litter,but not soil organic matter, whereas broadleaved tree plantings(on mineral soils) increase both. Because the current forest estate is relatively young, it isestimated to be accumulating about 2.5 million tonnes of carbonper year (1990), and to be still increasing in carbon density(tonnes C ha^-1). In order to maintain this rate of carbon removalfrom the atmosphere, planting would need to continue at a rateof 25–30 thousand ha of conifers or (theoretically) 10thousand ha of poplars per year (on good mineral soils). Itis noted that 2.5 million tonnes C is about 1.5 percent of theUK carbon emission, and may be similar to the natural carbonsink in Britain represented by wetlands and rivers.     

Tree planting in the Falkland Islands

The Falkland Islands experience a cool, windy and relativelydry climate. The soil is typically shallow peat over clay, althoughdeeper peat is locally present, and the natural vegetation isgrass-heath with no native trees or large shrubs. Climatic andsoil conditions, lack of knowledge and inadequate protectionhave hampered past attempts to establish a wide variety of treespecies. Successful results have been largely confined to favourablesites near houses and gardens. A very few sizeable tree plotsexist, notably at Hill Cove, Roy Cove, Weddell Island and CarcassIsland. Tree planting prospects were appraised during a visitin 1983. The creation of effective shelterbelts appeared feasible,using modern establishment techniques developed in upland Britain,correct species choice, careful site selection, adequate beltwidth, protection against damage, good technical supervisionand patience. The most promising species are Cupressus macrocarpa,Picea sitchensis (Queen Charlotte Islands origin), Pinus contorta(coastal origins only), Pinus radiata and Nothofagus betuloides.Using the same species, limited planting for wood productionmay also be possible on a very few sheltered, moist, accessiblesites. Small scale amenity and shelter planting for houses andgardens is clearly practicable. Imported planting stock willbe necessary due to the impracticality of raising sizeable quantitiesin the Islands.     

THIRTY YEARS' DEVELOPMENT OF AFFORESTATION TECHNIQUES ON DIFFICULT GROUND TYPES IN SOUTH-WEST SCOTLAND

The development of ploughing, draining, planting, and the useof turfs and of phosphate is considered in detail for each oftwo main types. For Molinia lands, the 1952 technique securesadequate drainage and a very considerable turnover of turf,and here the spruces Picea abies Karst. and P. sitcbensis Carr.remain the first choice. For Calluna lands, the developmentof methods and the choice of species is more difficult. Thespruces refuse to grow pure and unnursed on the poorer Callunatypes and the use of Scots pine (Pinus sylvestris L.), P. contortaDoug., the Mountain pine (P. uncinata Ramond), Japanese larch(Larix leptolepis Gord.), and Douglas fir (Pseudotsuga taxifoliaBrit.) is discussed. The main requirements for successful afforestationof these ground types are summarized.     

The Influence of Shelter and Weeds on Early Growth of Sitka Spruce and Lodgepole Pine

An experiment in Helmsdale Forest (Highland Region, Scotland)examined the effects of shelter and weed competition on Sitkaspruce (Picea sitchensis (Bong.) Can.) and lodgepole pine (Pinuscontorta Douglas ex Loudon). Different levels of shelter fromwind were achieved by using netting and were measured usingtatter flags. Three treatments compared weed competition byremoving no vegetation, heather (Calluna vulgaris L.) only orall ground vegetation respectively. Results indicate a definiterelationship between material lost from tatter flags and treedry weight at five years. Even the smallest increase in shelterresulted in increased growth of Sitka spruce and the beneficialeffect of shelter became most apparent 4 to 5 years after planting.Tree dry weight was found to be correlated with root collardiameter and height but not fifth year height increment. Resultsfrom weeding treatments were unclear and differed between species.This was because bird damage interacted with weeding, the completelyweeded plots being most heavily damaged; and because the methodof hand weeding (pulling out the whole plant including roots)damaged fine tree roots. Bird damage was prevented by nettingbut in unnetted plots it was found impossible to separate birddamage from other factors although it was clearly more seriouson lodgepole pine.     

Effect of Late-season Top-dressings of N (and K) applied to Conifer Transplants in the Nursery on their Survival and Growth on British Forest Sites

At two English forest nurseries, transplants of five coniferspecies—Picea sitchensis, Picea abies, Tsuga heterophylla,Abies grandis, and Pinus contorta—were grown with fertilizersupplying N, P, K, and Mg in amounts intended to be adequatefor producing healthy green trees with nutrient concentrationsin the ‘sufficiency range’ as determined by earlierexperiments. ‘Luxury uptake’ of nitrogen was obtainedwith top-dressings of ‘Nitro-Chalk’ applied in thenursery during early September, when top growth had nearly ceased.Tests of the effect of this extra N on forest establishmentwere repeated in four successive years under a wide range ofsoil and climatic conditions, keeping the trees in a cold storeduring each winter and planting them on forest sites in England,Scotland, or Wales during the following spring. Except for Grandfir, nitrogen advanced bud-break of all species during the firstsummer after planting and had no deleterious influence on survival.It tended to increase growth of Sitka spruce during the seasonafter planting, but in later years the differences became smallin relation to tree size. The effects on other species weresmall, except for one considerable decrease in the growth responseof Grand fir at a single site. Frost damage of Sitka spruce of Washington origin was severeon a Welsh and a Scottish site where this frost-sensitive provenancewould not normally be grown. At the Welsh, but not the Scottishsite, the nitrogen treatment increased the damage. In the few experiments (confined to Picea sitchensis) whichtested late-season potassium in the nursery, K concentrationswere increased from deficiency to barely sufficiency level;growth in the forest was increased in two of the four experiments.The extra K had no effect on frost damage.     

Using Distribution-Modifying Functions to Predict Variation in Frequency Distributions of Tree Heights during Plantation Establishment

The height growth of individual trees was followed during theestablishment phase of four progeny tests (three with Piceasitchensis and one with Larixxeurolepis). The relationshipsbetween annual height increment and height at the start of theyear (distribution-modifying functions; DMFs) were calculatedfor each year during establishment. These DMFs were used toproduce simulated frequency distributions for tree height. Althoughit has been stated that changes in the frequency distributionof plant sizes can be predicted from DMFs, the reliability ofthe functions is not good since, with these data sets, the functionsaccounted for a low percentage of individual tree growth. Whilethe functions do estimate the first moment of the distribution(the mean), they do not accurately predict the second and thirdmoments (standard deviation and skew). The primary reason forthe rapid spread in the frequency distribution is variationin growth of seedlings with similar heights. Successful modellingof the changes in frequency distribution can be accomplishedonly if variation in growth (of seedlings with the same initialheight) is included with the DMF. However, calculation of DMFscan be useful in defining the duration of planting check.     

Influence of Site Factors on the Response of Sitka Spruce to Fertilizer at Planting in Upland Britain

Data from Forestry Commission fertilizer experiments were analysedto determine the influence of site factors on the growth responseof Sitka spruce (Picea sitchensis (Bong.) Carr.) following applicationsof phosphate and potassium at time of planting. Multiple regressionanalysis revealed that growth response was influenced by soiltype and was related to the foliar nutrient levels of untreatedcontrols. Growth response to application of phosphate was alsoinfluenced by lithology. No relationships were found betweengrowth response and elevation or annual rainfall. Received 29 January 1990.     

Establishing forest tree species on peatland in a reflooded area of the Huleh Valley, Israel

The study evaluates the establishment performance of four treespecies (Ficus carica, Fraxinus syriaca, Salix acmophylla, Platanusorientalis) 3 years after planting in the peatland in the HulehValley. To develop good tree establishment and avoid uprooting,two types of soils were tested as alternatives for the rhizosphere.For each tree 6 m³ of soil (2 x 2 x 1.5 m) were replaced withriver bed alluvium or terra-rossa, in which the tree was planted.Control trees were planted directly in the peat. Changing therhizosphere soil type to river bed alluvium significantly improvedthe establishment and performance of Salix acmophylla and Fraxinussyriaca (survival, height, diameter and canopy shade area).Ficus carica was not affected by changing the soil in the rhizosphere,while Platanus orientalis was affected mainly in canopy shadearea. Terra-rossa improved establishment only of Salix acmophylla;it did not affect the other species.     

Influence of nurse birch and Scots pine seedlings on early aerial development of European beech seedlings in an open-field plantation of Central France

Beech woodland can be restored by direct planting of beech (Fagussylvatica L.) seedlings in abandoned areas, but this methodis generally avoided in forestry because of the growth difficultiesof beech in full-light conditions. This study tested a methodthat consists of planting beech seedlings in full-light conditionswith silver birch (Betula pendula Roth.) or Scots pine (Pinussylvestris L.) as nurse trees. A total of 65 two-year-old beechseedlings surrounded by either 3, 4, 5 or 6 pine or birch seedlingsor without competitors were planted in bare-soil open-fieldconditions in Central France. Tree growth and light availabilitywere monitored at the end of each of the following 3 years,and soil moisture was also measured the last year. At the endof the experiment, aerial biomass measurements were made onthe beeches. Results showed that relative beech growth in termsof diameter was significantly reduced by the local neighbouringtrees and that this reduction was particularly noticeable inthe pine treatments where there was extensive pine seedlingdevelopment. In contrast, relative beech height did not exhibitany significant variations among the treatments. Light availabilitywas decreased by the neighbouring trees, especially in the pinetreatments. Light reduction was more pronounced in the last2 years and in the middle or lower parts of the canopy of thesubject beech. Soil water content was lower under the pine canopiesthan under the birch canopies, and was positively correlatedto beech relative diameter growth. Specific leaf area, height-to-diameterratio and crown length-to-crown width ratio weakly but significantlyincreased with competition from the neighbours. Beech biomasspartitioning was only weakly affected by the treatments. Thisstudy showed that nurse trees tend to reduce beech growth butimprove form although effects remained weak due to the insufficientlength of the experiment. Further studies are also needed toquantify the effects of the neighbourhood on the growth of competitiveherbaceous vegetation and on changes in the microclimatic conditions.     

Variography and kriging allow screening Pinus pinaster resistant to Armillaria ostoyae in field conditions

Armillaria ostoyae is an important disease of Pinus pinasterin north-west Spain, which kills trees following a heterogeneousspatial structure. In a progeny trial of P. pinaster seedlings,spatial heterogeneity and autocorrelation of neighbour mortalitycaused by A. ostoyae impeded proper analysis of the diseaseincidence. We used variography and kriging methods to describethe spatial distribution of the infection probability and thegenetic variation of the resistance to A. ostoyae among families.The spatial structure of disease incidence was modelled, andthe probability of survival was corrected by kriging at eachtree location. Cumulative mortality 3 years after planting was65.1 per cent. Significant differences among P. pinaster familiesin terms of mortality to A. ostoyae were found, with low individual(h = 0.08) and moderate family (h = 0.35) heritability estimates. According to a theoretical semivariogram, the patch size ofthe disease incidence was 63 m wide. This is the first timevariography and kriging are used to select P. pinaster resistantto Armillaria root rot. It is concluded that geostatistics providesforest pathologists with a powerful tool for screening resistanttrees in field conditions.     

Control of the Pine Weevil, Hylobius abietis L., and of Hylastes species

Dipping the tops of plants, prior to planting, in a 5 per centoil-based emulsion formulation of DDT has given good controlof Hylobius but does not control Hylastes and may involve damagedue to phytotoxicity in some circumstances. Experimentationwith newly introduced water-based formulations of DDT and BHCconfirmed earlier findings that there are few significant differencesbetween possible materials. The need to dip whole plants inorder to control Hylastes, with minimum risk of phytotoxicity,has led to the use of 1.6 per cent water-based BHC on a fieldtrial scale with promising results.     

The effect of roots and litter of Calamagrostis canadensis on root sucker regeneration of Populus tremuloides

Marsh reed grass (Calamagrostis canadensis (Michx.) Beauv.)is a common, highly competitive grass native to the boreal mixedwoodforest. This grass increases in abundance after clear-cut loggingbut little is known about its effects on trembling aspen (Populustremuloides Michx.) sucker regeneration. The effects of Calamagrostissod and its litter on aspen regeneration were studied in twoseparate greenhouse studies. Calamagrostis sod did not affectthe initiation of suckers, but resulted in 30 per cent fewersuckers emerging above the soil that were smaller and had 40per cent less leaf area. Calamagrostis litter had little effecton the initiation and number of emerged suckers; however, itdelayed emergence by 10 days. The physical barrier by rootsand litter of Calamagrostis reduced or delayed the expansionof suckers and therefore prolonged their dependence on rootreserves. By the time the suckers reached the surface, theyhad to compete for light with Calamagrostis shoots that hademerged a week earlier. This, coupled with low soil temperaturesassociated with Calamagrostis in other experiments, will significantlyreduce the number and growth of suckers. Any reduction and delayin sucker emergence will decrease aspen regeneration and productivitysince the growing season in the boreal forest region is short.     

Norway or Sitka Spruce?

The deep and wide continental range and climate occupied bythe European species Picea abies is contrasted with the long,narrow, and humid coastal strip which the American species Piceasitchensis inhabits. Norway is the more plastic spruce and cansuffer thinner soils and much more drought, but neither spruceis a shallow rooter where soils are good and deep. Of the two,the litter of Sitka is less harmful to the soil. To date thereis no evidence that height for height Norway is more stableunder high wind pressures, but the belief that it is less sensitiveto frost than Sitka is well established. Sitka is far superiorto Norway for planting at high altitudes and in exposed placesand on Molinia peatlands in Britain, which accounts for thevast preponderance of the American species used in the westand north of the British Isles. The present popularity of Norwayspruce with foresters and timber merchants is admitted, butthe point is made that in planting it where Sitka could growwell, only some 75 per cent, of the volume will be secured.Finally, the types of site which each spruce requires and alsowhich each cannot take are considered in detail. A plea is madefor mixtures in certain circumstances, and the belief expoundedthat only deeper and better cultivation of the hardpacked materialunder-lying thin soils will make it possible to extend considerablyour acreage of really stable crops of these high-volume producers.     

Productivity of Jatropha curcas under smallholder farm conditions in Kenya

With the global bioenergy boom, the planting of jatropha (Jatropha curcas) was widely promoted by the private sector and non-government organizations as one of the candidate tree species for bioenergy in Kenya. This was motivated by the belief that it grows easily with minimal management requirements. The present study attempts to determine whether management practices by smallholder farmers, which are heterogeneous, are optimal for jatropha yields in Kenya. A survey conducted in different agro-ecological zones showed that yields are very low under Kenyan farm conditions. Regardless of the age and management condition, 41 % of the farmers obtained no seed yield, while 79 % obtained up to 0.1 kg/tree. This is dismal in comparison with the figures (up to 2.0 kg/tree) reported from elsewhere for 1–5 year old trees grown under similar conditions. Examination of farmer management practices indicated that irrigation, manuring and weeding, in order to maximize yields, could be offset by misapplication of other components especially, selection of planting materials, timing of planting and choice of intercrops during the establishment phases. This indicates that the anticipated high yields have not been achieved partly because growers are still using unimproved germplasm, management practices are sub-optimal, and the biophysical boundaries of high jatropha yield are poorly defined. Thus at the current stage, jatropha should not be grown by smallholder farmers in Kenya because of low or dismal productivity. If jatropha is to play a role in the pro-poor bioenergy development, future projects need to identify management recommendations that optimize yields. This also needs to take into consideration the preferences and constraints of farm households on labor and land allocation to other farm and livelihood activities.     

Infection by Armillaria mellea and some Factors Affecting Host Resistance and the Severity of Disease

Infection by A. mellea in Britain occurs by means of rhizomorphs;the transfer of mycelium at root contacts is probably not importantas a means of spread. Following the initial phase of rhizomorphpenetration, established infection in the cambium is precededby ectotrophic spread of mycelium in the bark scales. Field investigation confirmed reports in the literature thatin susceptible conifers the greatest number of deaths generallyoccurs approximately 6–8 years after planting. However,attacks can also occur in much older crops and the reasons forthis are discussed. Inoculation experiments showed that suppressed trees and thoseexperiencing conditions of reduced light intensity are moresusceptible to infection than dominant trees and trees in fulllight. Species susceptibility in a variety of soils was studiedby inoculation of trees 20–30 cm tall. Of the coniferstested Pseudotsuga menziesii and Abies grandis were more resistantthan Picea abies, P. sitchensis, Larix kaempferi and Pinus sylvestris.Quercus robur and Fagus sylvatica were more resistant than allthe conifers except A. grandis. Soil type influenced diseasedevelopment and the proportion of trees infected was higherin an acidic sand soil than in an alkaline clay soil.     

The Summerwood: Springwood Ratio in Conifers: How it arises, varies, and affects end use for timber, board, and paper

A theoretical discussion of variation in summerwood and springwoodcontents among conifers. Three methods of measuring these, bycross-sectional area of logs, by dryweight fibre percentage,and by nominal specific gravity, are compared. High-summerwood tissues have a nominal specific gravity of 0?45or over; low-summerwood tissues have a specific gravity below0?45. All conifers have a low summerwood content in their juvenilewood or core wood formed towards their stem-tips. In Pinus,Larix, and Pseudotsuga the summerwood percentage increases markedlywith age, but only in the outer layers towards the butt; inPicea, Abies, and Tsuga similar increases occur, but high-summerwoodtissues are seldom found. Within any species, and for any particulargrowth rate, low-summerwood tissues are characteristic of regionsof high relative humidity where summer water deficits rarelyoccur, such as high altitudes, far northern latitudes, and themaritime climate of western Britain. High-summerwood tissuesdevelop where summer temperatures are high, with associatedstrong sunshine, low relative humidity, and frequent summerwater deficits. High-summerwood tissues have greater strength in compressionand bending, relative to volume; but low-summerwood tissueshave greater strength relative to their weight. Low-summerwoodmaterial has proved satisfactory for most structural purposes,and for the manufacture of several kinds of artificial board.Its technical properties for the making of many types of paperare excellent, provided high resistance to tearing is not required.Likely summerwood content should guide planting programmes andmarketing policies.     

杨树速生丰产林配套施肥技术试验研究Ⅱ.追肥试验

几种N、P、K复合肥及尿素进行不同配比、不同量和不同施肥方式作追肥试验,结果表明追肥对造林第1年杨树胸径生长量的影响要大于对高生长的影响,最佳处理的生长量比对照增加1倍以上.不同肥种的作用效果差异表现为尿素＞3号肥＞2号肥＞1号肥.造林第2年杨树的追肥试验结果表明各种处理对生长量的增幅较大,追肥后生长量的变化幅度比造林第1年要小,肥种对生长量的增幅效果表现为2号肥＞1号肥＞尿素＞3号肥.分次施肥方式的作用效果优于一次性施入方式.施肥效果较好的时间为6月中旬.