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1.
Johansson  Tord 《Forestry》2005,78(3):249-262
The objective was to determine stem volume models for grey andcommon alders and, based on the models, stand volume for naturallyregenerated grey and common alder stands was summarized. Basicdensity for grey and common alders and mean annual growth forstands was estimated. Net volume accretion data were collectedfrom 24 stands of grey alder (Alnus incana (L.) Moench) and31 stands of common alder (Alnus glutinosa (L.) Gaertner) inSweden. The stands ranged in latitude from 58 to 64° N andfrom 56 to 62° N for grey and common alder, respectively.The mean age of grey and common alder stands was 41 years and48 years, respectively, the mean stand density 1726 stems ha–1and 1078 stems ha–1, and the mean diameter at breast height(over bark) was 20 cm and 21 cm. Stem volume equations weredeveloped for grey and common alders. The adopted model forgrey alder was based on diameter at breast height and height.For common alder, crown height was added to diameter and height.Mean standing volume (over bark) for grey and common alder standswas 428 and 374 m3 ha–1. Mean annual growth for grey andcommon alder stands was 12.0 m3 and 8.4 m3 a–1 ha–1,respectively. Basic density (under bark), for grey and commonalder stems was 359 and 427 kg m–3, respectively. Thebasic density (under bark) for the lowest twigs in the crownand in the lateral part of the crown was 415 and 421 kg m–3for grey alder and 423 and 423 kg m–3 for common alder.  相似文献   

2.
ATA  C. 《Forestry》1989,62(3):285-296
Pinus nigra Arnold var. pallasiana Endl. and Abies equi-trojaniAschers-Sinten are indigenous species of Turkey. The area ofPinus nigra is very large (more than 2 million hectares) occurringin the west, south and north of Turkey. However, Abies equi-trojanioccurs only in the west of Turkey in the Ida Mountains (Kazdagi)and is of limited area (5500 ha).These two species naturallyform both mixed stands and pure stands in the Ida Mountains. When mixed stands of Pinus nigra and Abies equi-trojani areregenerated, if the seedlings of these two species regeneratesimultaneously, the Pinus nigra will be eliminated from thestand in 15 to 25 years because of the rapid growth of Abiesequi-trojani. In different site conditions, Abies equi-trojanireaches 22–30 m in height and 40–65 cm in diameterin 70 years, whereas Pinus nigra reaches 17–22 m in heightand 25–40cm in diameter in the same period in the sameforest sites.  相似文献   

3.
The growing stock assessment of three different teak forest stands (Tuirial: 500 m asl, Sairang: 200 m asl and Phunchawng: 550 m asl) was done in 2006 in Mizoram, India. Five diameter classes were arbitrarily established for knowing the volume attribute data and population structure, viz. a (10-20 cm), b (20-30 cm), c (30-40 cm), d (40-50 cm), and e (50-60 cm). Results revealed that the density of the individuals among the studied stands varied from 280 stems/ha to 620 stems/ha. The average diameter of all the individuals ranged between 27.48 cm and 35.43 cm. Similarly, the average height was oscillated between 17.87 m and 22.24 m. The total basal area was recorded between 24.28 m2.ha-1 and 45.80 m2.ha"l. The maximum and minimum values of total growing stock under all the diameter classes were 669.01 m3.ha-1 and 284.7 m3.ha-1, respectively. The representation of population structure of different stands explained that the perpetuation of this species was ensured for a quite long time.  相似文献   

4.
Chrimes  Dillon; Nilson  Kristina 《Forestry》2005,78(4):433-442
The study aimed specifically at investigating if canopy opennesswas a better predictor of the height growth of Norway spruce(Picea abies (L.) Karst.) advance regeneration than overstoreybasal area or overstorey standing volume. In 1990, a field experimentwith 3 x 2 factorial design and two replications (blocks) wasestablished in an uneven-aged Norway spruce forest. Plots hada net plot area of 30 x 30 m, each with a 10-m-wide treatedbuffer zone. Three overstorey density levels retained approximately15, 40 and 70 per cent of the pre-harvest overstorey standingvolume and were allotted to the plots. Two types of thinningthat harvested smaller trees or harvested larger trees wererandomly allocated to each pair of overstorey density plots.In mid-June 2000, canopy openness was estimated from hemisphericalphotographs taken at five marked points in the centre of eachof the plots at 0.9 m from ground to the top of the ‘fish-eye’camera lens. Regression results showed that canopy opennesswas a better predictor of height increments of spruce seedlings(0.1< height < 0.5 m), saplings (0.5 height < 2.0m), and small trees (height 2.0 m, diameter at 1.3 m height< 5 cm) than with overstorey basal area (m2 ha–1) oroverstorey standing volume (m3 ha–1). The height incrementof the spruce advance regeneration was not significantly correlatedto stand basal area or to standing volume. Overstorey basalarea in the net plots was significantly negative (P 0.05) withmean canopy openness estimates, and the r2 value was 0.40. Resultsindicated that basal area was not linearly related to canopyopenness as it increased, which might explain the lack of predictivepower of retained basal area on spruce regeneration height indense stands in boreal Sweden.  相似文献   

5.
Managing birch woodlands for the production of quality timber   总被引:2,自引:0,他引:2  
CAMERON  A. D. 《Forestry》1996,69(4):357-371
Interest in silver birch (Betula pendula Roth) and downy birch(Betula pubescens Ehrh.) has greatly increased in recent yearspartly as a result of pressures to restore and expand nativewoodlands but also due to renewed interest in birch as a treecapable of producing quality timber. Despite the many advantagesof birch as a commercial timber tree—ease of establishment,fast growth on good sites, high value timber and a short rotation,it has a poor reputation in Britain largely as a result of thepoor form of the existing, mainly unmanaged resource. The followingpoints need to be considered if stands of quality birch treesare to be produced in an economical timescale. (1) Sites: silverbirch needs good sites that are relatively well drained withlight mineral soils. Downy birch does well on moist to wet sites.(2) Regeneration: natural regeneration through a shelterwoodis the preferred system of regenerating birch as some overheadprotection is beneficial to germination success. About 20–40seed trees should be left per hectare. Good ground preparationand control of grazing are essential. The vast majority of seedlingsare recruited in the first year of the regeneration cycle thereforeplanting should be considered if the initial regeneration successis poor. Direct seeding is also a successful method of regeneration.Birch readily regenerates naturally into suitably prepared openareas next to existing birch woods but these should not be toobig, e.g. gaps or strips 20–60 m wide have been suggestedin the literature. (3) Maintenance: density of regenerationneeds to be reduced to about 2500–3000 stems ha–1by the time the trees are about 3–6 m tall. Birch seedlingsmust always be taller than the competing vegetation. (4) Thinning:thinning should begin when the mean height of the stand is about8–10 m. At this point at least half the number of treesshould be removed with the emphasis on retaining dominants andco-dominants of good form. The aim is to maintain about halfthe height of the tree as living crown to sustain a high rateof growth. Additional thinnings will be required at intervalsof 5 to 7 years and final thinning should leave around 300–500stems ha–1. (5) Rotation: a rotation of 40–50 yearsis possible on good sites and perhaps 50–55 years on lessfavourable sites.  相似文献   

6.
In autumn 2001, 15 canopy gaps were selected for study in RumerhedgeWood, a semi-natural, mesotrophic beechwood in southern England.The gaps were located in mature, beech-dominated stands, andhad originated from openings created during a thinning in theearly 1980s and wind damage in 1987/1990 and/or the consequentsalvage operations. The extent of each gap and surrounding treeswere mapped. Tree/shrub regeneration, ground vegetation, bareearth, leaf litter and canopy openness (using a canopy-scope)were measured within and around the gaps using a 5 x 5-m gridand placing a 1 x 1-m quadrat at each grid intersection (totalnumber of quadrats = 400). Most of the gaps were <75 m2 inarea. The largest was 241 m2. They were generally irregularin shape and there was little or no understorey present. Mostsurrounding trees were beech Fagus sylvatica L. Bramble Rubusfruticosus L. formed a moderate to dense ground vegetation belowmost gaps and declined around the edges only once the gap openingwas substantially obscured. Apart from a few larger saplings,most regeneration was small and of beech. Most of the latterappeared to be in their fifth or sixth growing season, were10–35 cm tall, had an erect base and flat top, had increasedby <5 cm in height during 2001 and were not browsed by deer.Their height and growth form was related to (1) their positionwithin gaps, (2) the degree of canopy openness and (3) the coverof ground vegetation. This was translated into the followingzonation—(1) around the centre of larger gaps: canopyopenness increased to >15 per cent; bramble cover was nearcomplete; litter depth was low; many places had no beech seedlings,but some of the few present were among the tallest, most uprightand fastest growing; (2) towards the edges of the large gapsor directly below smaller gaps: canopy openness was about 4–10per cent; bramble cover was slightly less; beech seedlings weremoderately abundant but patchy, generally shorter, more flattopped and slow growing than in the gap centre, albeit somewere still among the tallest, most upright and fastest growing;(3) beyond the edge of the large/medium gaps (with the gap onlypartially visible) or directly below very small gaps: canopyopenness was only about 2–3 per cent; bramble was muchreduced; beech seedlings were at their most abundant but stillpatchy in distribution and even shorter, more flat topped andslower growing than in the above zone; (4) in an outer zonebeyond or almost beyond the sight of the gaps: canopy opennesswas <2 per cent; bramble was weak and sparse; beech seedlingswere mostly at low densities and predominately short, slow growingand flat topped. This ring pattern of beech regeneration appearedto relate mainly to (1) differences in light availability affectingthe survival, growth rate and form of seedlings; (2) competitionfrom bramble and possibly (3) limited dispersal of beech seedinto gaps. Recommendations are given for managers who wish touse natural regeneration to restock beech woodland.  相似文献   

7.
SHORTEN  MONICA 《Forestry》1957,30(2):151-172
The paper examines the replies received from foresters of theForestry Commissionto questionnaires sent out at the author'ssuggestion in 1954, 1955, and 1956 on the damage caused to ForestryCommission woodlands by the two squirrels, Sciurus carolinensisand S. vulgaris leucourus, during the forest years 1954–6.The inquiry was primarily concerned with S. carolinensis, thegrey squirrel, for the killing of which rewards have been offeredsince 1953, ut, for 1955 and 1956, information was sought alsoabout the red squirrel. The most serious economic damage doneby both squirrels is considered to be the stripping of barkfrom the stemsof growing trees and it is this damage which isexamined. The information received is sifted critically andthe results summarized in thirteen tables andin two diagrams.  相似文献   

8.
Dixon  F.L.; Clay  D.V.; Willoughby  I. 《Forestry》2005,78(4):353-364
The selective herbicide clopyralid is often used to controlcompeting Cirsium arvense in newly planted woodlands. When appliedas an overall spray at different dates in the spring (at 0.2kg acid equivalent (a.e.) ha–1) to 10 tree species (Fraxinusexcelsior, Prunus avium, Quercus robur, Acer pseudoplatanus,Populus x canadensis cv. ‘Ghoy’, Pseudotsuga menziesii,Pinus nigra ssp. laricio, Larix kaempferi, Picea abies and Piceasitchensis) it did not reduce survival, and had little effecton growth. However, some species showed distortion of the youngestsprayed leaves or needles for several weeks after treatment,particularly F. excelsior, L. kaempferi and P. x canadensis.Sequential applications of clopyralid (first at 0.1 kg a.e.ha–1 followed by 0.2 kg a.e. ha–1 after 3 weeks),which are often required to control C. arvense, did not leadto increased leaf damage or growth reduction. Mixtures of clopyralidwith selective graminicides (cycloxydim at 0.45 kg active ingredient(a.i.) ha–1; fluazifop-p-butyl at 0.38 kg a.i. ha–1and propaquizafop at 0.15 kg a.i. ha–1) did not causesignificant adverse effects on survival or growth of any species.If herbicides are required to control mixed stands of susceptibleproblem weeds such as C. arvense and grasses which are overtoppingyoung trees, these herbicide mixtures, applied as overall sprays,are less likely to cause damage to trees than attempts to usedirected applications of broad-spectrum foliar-acting herbicides.  相似文献   

9.
VALINGER  E.; PETTERSSON  N. 《Forestry》1996,69(1):25-33
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   

10.
Long-term research plots in multi-aged stands managed with theplenter system were assessed to evaluate sustainability of theplenter system in Central Europe. Plots primarily consistedof Norway spruce (Picea abies (L.) Karst., silver fir (Abiesalba Mill.) or European beech (Fagus sylvatica L.) and weremeasured for seven to 16 measurement intervals over 60–91years. Sustainability was assessed with four types of criteria:stand density, tree species diversity, basal area increment,and stand structure. Comparable even-aged stands were also analysedto compare and evaluate the performance of the measures of sustainability.Measures of species diversity, increment and stand structuraldiversity generally experienced increasing trends over timein these even-aged stands. Basal area generally increased andtrees ha-1 decreased in multi-aged stands following similarpatterns as in even-aged stands. These results suggest thatthe plenter system is still evolving and is not the model ofsustainability often assumed. Many of the measures used havepotential as indicators of sustainability in multi-aged stands.  相似文献   

11.
A case study was conducted in beech forests of northern Iran to determine the effect of the created gaps on some soil properties in beech stand. Changes of soil properties in small (60 150 m 2 ), medium (151 241 m 2 ), large (242 332 m 2 ) and very large (333 550 m 2 ) gaps, as well as under closed stands were studied eight years after the gap creation. Soil samples were taken from three depths, 0 10, 10 20 and 20 30 cm. The gaps were different from their around undisturbed stands in terms of the following soil parameters: Mg +2 concentration of 0 10 cm at medium gap size, bulk density of 10 20 cm at very large gap size as well as K + and Ca +2 concentrations at 20 30 cm at small and large gap sizes, respectively. Furthermore, the size of the gaps had no effect on soil characteristics through the whole profile. Water saturation percent (Sp %) at 0 10cm as well as P and Mg +2 at 20 30 cm was different amongst undisturbed stands around different gap sizes. The center and the edges of the gap were different only in terms of organic carbon at the depth of 10 20 cm. Significant differences were observed between gaps andclosed canopy regarding P and Ca +2 at depth 0 10 cm and 10 20 cm, respectively. It can be concluded that applied silvicultural system for harvesting trees which created these gaps might be suitable for conservation and forest management in the region.  相似文献   

12.
WORRELL  R. 《Forestry》1992,65(3):253-280
Data describing the growth, survival and stem form of: a) Europeancontinental, and b) British provenances of trees native to Britainwere collated from Forestry Commission records. The growth ratesof European continental provenances of Scots pine (Pinus sylvestris),silver birch (Betulo pendula), sessile oak (Quercus petraea)and common alder (Alnus glutinosa) were inferior to those ofBritish provenances in 90 per cent of cases. European provenancesof these species also showed inferior survival. The growth ratesof continental provenances of beech (Fagus sylvatica) were superiorto British provenances in about 50 per cent of cases, provenancesfrom northern France, Belgium and Holland being the fastestgrowing. Relationships between the relative height growth offoreign provenances and latitude were demonstrated for Scotspine, silver birch and beech (relative height growth = the heightgrowth of a foreign provenance expressed relative to that ofBritish provenances at the same site). The continental provenancesthat grew best originated at 0–4° south of the latitudesof the planting sites. Relative height growth decreased bothnorth and south of these latitudes. In the case of oak, relativeheight growth did not vary widely between origins. The survivalof continental provenances of Scots pine was particularly pooron exposed upland sites. The stem form of British provenancesof Scots pine was intermediate between Fennoscandian provenancesand provenances from the rest of Europe. In oak and beech therewas generally little difference in stem form between Britishand continental provenances, but the best continental provenances(Belgian beech; French oak) were most reliable. The growth andsurvival of native trees is interpreted in the light of thepost-glacial history of these species. The implications regardingthe continued use of seed of native hardwoods imported fromcontinental Europe are discussed.  相似文献   

13.
Six broadleaved tree species and Picea abies (L.) Karst. wereplanted under spruce plantations of varying densities, in Sweden.Treatments included control (994 stems ha–1), dense (538stems ha–1), sparse (294 stems ha–1) and gap (0stems ha–1) overstory treatments. There was an increasein height and diameter growth from control to sparse overstorytreatment of all underplanted tree species except for ash (Fraxinusexcelsior L.) and Norway maple (Acer platanoides L.). Site conditionsmay have hampered the growth of these species, as well as wildcherry (Prunus avium L.). Both oak (Quercus robur L.) and sprucehad greater growth in the gap treatment, relative to the othertreatments. Insecticide application did not influence seedlinggrowth or survival. The performance of beech (Fagus sylvaticaL.), lime (Tilia cordata Mill.), spruce and oak was consistentwith shade tolerance ranking. Beech and lime had a very highsurvival rate, even under the densest canopy. The growth andmortality of ash, maple and wild cherry differed significantlyfrom what was expected. This experiment demonstrated significantvariation in interspecific growth and mortality between sevenplanted tree species in relation to canopy density. Correctsite and species selection is crucial when underplanting inshelterwood systems.  相似文献   

14.
Controlling Rhododendron spp. in the Turkish Black Sea Region   总被引:3,自引:0,他引:3  
Rhododendrons (Rhododendron ponticum L. and Rhododendron luteumSweet) dominate the understories of the mesic forests of theBlack Sea Region (BSR) of Turkey. They dramatically reduce forestgrowth and regeneration and local plant diversity. This paperreports the results of a large rhododendron control experimentestablished on two different sites in the western and easternBSR of Turkey 5 years after treatments (YAT). The paper alsopresents the second-year results of a second experiment in whichthe foliar herbicides of the previous experiment were testedon rhododendron at much lower rates on a western BSR site. FiveYAT, grubbing and foliar spraying were still the best rhododendroncontrol methods in the first experiment. Cut-stump sprayingprovided an intermediate level of woody control. Hand-cuttingwas ineffective on R. ponticum and did not significantly differfrom the control treatment in rhododendron basal area 5 YAT.The performance ratings of foliar triclopyr ester and imazapyrfor woody control in both experiments were rate dependent. Athigh rates ranging between 2.6 and 5.8 kg ae ha–1, foliarimazapyr controlled both rhododendron species significantlybetter than foliar triclopyr ester in the first experiment,suggesting enhanced imazapyr translocation to the roots. Someoff-target damage was observed in the beech overstory for imazapyrat high rates. The performance ratings of these foliar herbicideswere significantly reversed in the second experiment 2 YAT,where much lower rates were used (0.3–2.0 kg ae ha–1)than in the first experiment. Insufficient imazapyr accumulationin rhododendron roots might account for the poor impact of thisherbicide. No beech damage was apparent from any of the herbicidesin the second experiment. The low-rate foliar triclopyr esteris recommended for effective and cost-efficient rhododendroncontrol.  相似文献   

15.
THE INFLUENCE OF WEATHER ON THE FREQUENCY OF BEECH MAST YEARS IN ENGLAND   总被引:4,自引:0,他引:4  
MATTHEWS  J. D. 《Forestry》1955,28(2):107-116
Records are collected of beech masts (Fagus sylvatica L.) forthe period 1921–50 and these records are compared in atable with the temperature, rainfall, and sunshine figures ofthe 5 months, May to September, of the preceding summer. Itis shown that there are significant correlations between thesize of mast and (i) July air temperature and (ii) July sunshine.Other factors affecting mast are considered and in particularthe damaging effect of spring frosts to the flowers of beech.  相似文献   

16.
Light Use Efficiency and Woody Biomass Production of Poplar and Willow   总被引:1,自引:0,他引:1  
Stands of clonal Salix viminalis (in 1985) and Populus trichocarpa(in 1986) were grown for one growing season from cuttings incontainers, at 0.3 m spacing, supplied with trickle irrigationand nutrients. Woody biomass production (Bw) in the first yearwas analysed as the product of the proportion of dry matterpartitioned to wood ({macron}), the seasonal mean efficiencywith which intercepted light was used to produce dry matter({macron}), the mean fraction of incident light interceptedby the canopies (f{macron}), and the amount of incoming solarradiation over the season (A). Thus, Bw = {macron}f{macron}{macron}A. For Salix, Bw=10 t ha–1y–1, while for Populus, Bw= 5 t ha–1y–1, mainly because of differences in{macron} and f{macron}. The Populus partitioned more dry matterto roots (and correspondingly less to stems) and interceptedless light over the growing season. The Salix and Populus cloneshad surprisingly similar ({macron}) values, namely 1. 58 and1. 50 g MJ–1, respectively (based on total dry matterand total solar radiation), which are very like the {macron}values measured on C3 agricultural crops in Britain. Also, theSalix and Populus clones produced canopies with similar lightextinction coefficients and hence similar relationships betweenfractional interception and leaf area index.  相似文献   

17.
Johansson  Tord 《Forestry》2007,80(1):41-52
The objective of the study was to quantify above- and below-stumpbiomass of silver (Betula pendula Roth) and downy (Betula pubescensEhrh.) birches planted at four spacing intervals and growingon two soil types on an area of farmland. The 12-year-old bircheshad been grown at four spacings (1.3, 1.5, 1.8 and 2.6 m) ontwo sites: one on medium clay soil and the other on fine sandsoil. The dry weight of the stem, branches, leaves, stumps androots was estimated by drying and weighing sub-samples. Theprojected leaf area (PLA) m–2 of trees, leaf area indexof stands and basic density (kg m–3)of stems were alsoestimated. A significant greater dry weight of stem, branches,stump and roots and species and spacing for pendula birch werefound. The root length of silver birch was significantly greaterthan that for downy birch and for both species the root lengthwas greatest at the widest spacing (2.6 m). There was also asignificant difference between leaf weights of birch of thesame species growing on the two soil types. Significant differenceswere also found between PLA and species, and for both species,between PLA spacing. Basic density of stems was significantlydifferent between soil types. Equations for estimating the above-groundbiomass and root biomass from diameter at breast height weredeveloped for birches growing on fine sand and on medium claysoils. The total biomass production per hectare on fine sandwas higher for silver birch (19.9–65.9 tonnes ha–1),than for downy birch (13.0–48.3 tonnes ha–1). Onmedium clay soil, total biomass production for silver and downybirches was 30.8–52.8 and 16.8–42.8 tonnes ha–1,respectively.  相似文献   

18.
HARMER  R.; KERR  G.; BOSWELL  R. 《Forestry》1997,70(3):199-210
A survey of 78 sites in southern England with approved managementplans for restocking by natural regeneration was made duringthe summers of 1993 and 1994. The following features were recorded:species, stocking, canopy cover and seed-bearing potential oftrees present in the overstorey; species and canopy cover ofthe understorey; ground cover; species, browsing damage, numberand heights of tree seedlings. In general, sites were poorlystocked with overstorey trees having an average of 135 stemsha–1 and a mean canopy cover of 36 per cent. Similarly,the understoreys were poorly developed with an average coverof only 23 per cent. Twenty-nine species of tree were foundin the overstorey, Quercus spp. and Fraxinus excelsior werethe most common. Many of the stems present had poor seed-bearingpotential. Cover of the ground flora often exceeded 75 per cent.Seedlings were present on most sites, with F. excelsior andBetula pendula being most abundant with mean seedling densitiesexceeding 10000 ha–1. Most seedlings were >20 cm tall,few exceeded 120 cm. About 30 per cent of seedlings were browsed.The results are related to current guidance and the future prospectsfor use of natural regeneration.  相似文献   

19.
The composition of forest litter and understorey layer, andfungal biomass (in terms of ergosterol) were measured in eightsubplots over a winter–spring period (January to April).The sampling site was positioned in a range of woodland habitats(variously dominated by beech, Fagus sylvatica; birch, Betulapendula x pubescens, and oak Quercus petraea) and a clear areacovered with grass (dominated by Holcus lanatus). The resultswere analysed together with data on bacteria and microinvertebratesavailable from parallel research. Levels of ergosterol in individualsubplots ranged between 50 and 160 µg g–1 DW. Fungalbiomass decreased in March, and then increased significantlyin April. Stepwise regression models for ergosterol indicatedpositive relationships with moisture content (February), bacteria(all but February and March), flagellates (February) and plant-feedingnematodes and flies (January, overall). The relationships withroots, seeds, the collective variable ‘other microinvertebrates’(all March), amoebae (February) and fragments (March, overall)were negative, while the relationship between fungi- and microbial-feedingnematodes changed sign between February (–) and March(+). Results of analysis of covariance for fungal ergosterolwere significant only for January and the combined dataset.In January, fungi were shown to be significantly related toamoebae, bacteria and a collembolan Folsomia candida, whilethe only significant predictor returned by the overall modelwas bacteria. Correlation analysis confirmed some effects alreadynoted, and revealed a number of further interactions. The resultshighlighted the complexity of factors influencing temporal dynamicsand spatial variability of fungal biomass in forest litter.Most of the registered interactions appeared to be transient,and this should be taken into account while interpreting environmentalobservations. Interpretation of the specific relationships isgiven and implications for further research and overall ecosystemfunctioning are discussed.  相似文献   

20.
SCHoNENBERGER  WALTER 《Forestry》1984,57(1):59-73
In the alpine timberline ecotone at 1350 m in the CraigieburnRange, New Zealand, four distinct mountain beech stand types(a pole, a coppice, a high forest and a shrublike stand) wereanalysed for stand biomass and leaf area by means of allomet-ricregressions based on stem diameter. Differences between stand types in terms of age, structure,biomass and leaf area are interpreted as development stagesafter stand breakdowns due to external impacts. Vegetative reproduction,mainly coppicing, plays an important part in stand regeneration. The young pole stand had 177 t ha–1, the coppice stand272 t ha–1, and the mature high forest stand 323 t ha–1aboveground dry weight. A low mountain beech shrub stand withgnarled, windshaped dwarf trees had only 135 t ha–1. Foliageaccounted for only 3–5% in all stands, the leaf area indexwas also low, at 3.0 in the shrub stand and 3.7–7.4 inthe forest stands. The low foliage proportion is consideredto be a response to the harsh environment.  相似文献   

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