Growth and mortality in underplanted tree seedlings in response to variations in canopy closure of Norway spruce stands

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.     

Decay in Norway Spruce Caused by Stereum sanguinolentum Alb. & Schw. ex Fr. Developing from Extraction Wounds

In two stands of Norway spruce (Picea abies (L.) Karst.), plantedin 1952 and 1929 in Yair Hill Forest and Glentress Forest, BordersRegion, two per cent of the trees examined in 1983 had extractiondamage on stems and superficial roots. Extraction wounds were4 and 8 years old respectively and ranged in size from 52 to1099 cm². Infection frequency of the damaged trees was 47 percent and 54 per cent respectively. Stereum sanguinolentum wasthe most common fungus isolated, accompanied by Trichodermaviride Fr; Chaetomium cochlioides Palliser and Heterobasidionannosum (Fr.) Bref. The frequency of isolation of S. sanguinolentumincreased progressively in samples taken from the outside ofstems inwards, whereas the other microorganisms present showedthe opposite pattern. In four trees, T. viride overgrew S. sanguinolentumin the the decay columns. Positive correlations were demonstratedbetween surface area of wounds and vertical extension of decay,tree volume and decay volume, and diameter of stem at breastheight (DBH) and decay volume; whereas a negative correlationoccurred between number of growth rings per 5 cm (measured inwardsfrom the outside of the bole) and radial penetration of decay.The results confirm the importance of S. sanguinolentum as awound pathogen.     

Factors influencing tree species diversity and Betula alleghaniensis establishment in silvicultural openings

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.     

The Pine Shoot Beetle Tomicus piniperda as a Vector of Blue Stain Fungi to Windblown Pine

After the great gale of 1987, the role of the pine shoot beetle,Tomicus piniperda, as a vector of blue stain fungi to windblownpine in southern England was examined by macerating adult beetlesand culturing the macerate on various agar media. Isolationswere also made from pine tissue associated with beetle galleriesand tunnels. Using data from between three and nine sites, it was found that17 per cent of the overwintered adult beetles were carryingfast-growing Leptographium spp. as they began to construct breedinggalleries in spring 1988. More than half the new generationof adult beetles were contaminated with these fungi when theyemerged in June-July 1988, but this proportion dropped as thelife cycle of shoot-feeding and overwintering progressed. Itaveraged 26 per cent at the time of brood gallery constructionin spring 1989. Isolations made from pine tissue around the galleries also showedchanges in the frequency of blue stain fungi. Of early broodgalleries 25 per cent yielded Leptographium, while the figurefor late galleries was 51 per cent. These results were consistentwith the direct introduction of Leptographium by the parentbeetles into some galleries, and the subsequent rapid hyphalgrowth of the fungus within the tree to colonize tissue adjacentto other galleries. The principal species identified was L. wingfieldii. However,L. lundbergii, L. huntii, L. procerum and an unidentified Leptographiumspecies were occasionally recorded, both on the beetles andin the trees. Graphium species were quite common also. In addition,the black yeasts, Hormonema dematioides and Aureobasidium pullulans,were frequently present, particularly in the pine shoot samples.     

Characteristics of lowland broadleaved woodland being restocked by natural regeneration

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.     

An Analysis of Peridermium Stem Rust of Scots Pine in Thetford Forest in 1984 and 1985

The status of stem rust (Peridermium pini or (Pers.) Lev.) inScots pine (Pinus sylvestris L.) in the central block of Thetfordforest, East Anglia was determined by means of detailed analysisof freshly felled trees. A total of 935 trees was examined,these comprising c. 100 from each of nine compartments plantedbetween 1922 and 1933. Lesions in all stages of development were found; from thosein their first year of sporulation on young twigs to those whichhad been established for many years on the trunk and main branches.Death of cambium occurred typically on lesions on shoots thatwere more than five years of age. Downward growth of the funguswas estimated to average between 4.7 and 5.6 cm per year, whenbased on the length of sporulating tissue on young twigs, and6.3 cm per year when based on cambial killing in trunk lesions.The average rate of circumferential killing of trunk lesionsaveraged 4.3 crn per year (i.e. 2.2 cm in each direction). Therewas no evidence that wounds provided a significant infectioncourt. A strong association was found between the presence of the ‘purplemould’ (Tuberculina maxima) and an absence of sporulationby the rust fungus. However, there was no evidence for lesioninactivation by T. maxima. Data are presented on the distribution of disease between sitesand between trees. Five per cent of the total sample of treeswere dead and an additional 12 per cent had crown symptoms associatedwith girdling trunk lesions. Among the 775 trees with predominantlyhealthy crowns, it is estimated that 9 per cent would have diedwithin 5 years, 15 per cent within 10 years and 22 per centwithin 20 years. By contrast 66 per cent had no disease at all,probably for genetic reasons. It is concluded that, althoughthe disease situation is serious, there is no requirement fora major change to be made in the felling programme for the pre-warScots pine in Thetford.     

Impregnation of Norway spruce (Picea abies L. Karst.) wood by hydrophobic oil and dispersion patterns in different tissues

Wood from Norway spruce (Picea abies L. Karst.) is biologicallydegraded in exposed conditions. It also has anatomical featuresthat make it difficult to impregnate with preservatives by currentlyavailable industrial processes. In the study reported here,we used the new Linotech process to impregnate Norway sprucewood with hydrophobic linseed oil and then quantified its uptakeand dispersal in anatomically distinct wood tissues. We alsoinvestigated the effects of the wood moisture content on theresults of the impregnation. Samples (500 x 25 x 25 mm) weretaken from 15 trees in a coniferous forest in northern Sweden(64° 10' N, 160–320 m a.s.l.). The parameters forthe Linotech process were 2–3 h treatment time at 0.8–1.4MPa and 60–140°C. To determine the level of uptake,the linseed oil was extracted from the impregnated wood usingmethyl-tertiary-butyl-ether. The uptake was quantitatively analysedby comparing X-ray microdensitometry values obtained followingimpregnation both before and after oil removal. In earlywood,initial moisture content had an obvious effect on the impregnationresult. Six times more oil was taken up when the moisture contentwas greater than ~150 per cent than when it was less than 30per cent. Theoretical calculations, based on density levels,suggest that the water-filled porosity of the wood (water volumedivided by porosity volume) was positively correlated with thelinseed oil uptake, and more strongly correlated in earlywoodthan in latewood. There were also significant differences inuptake between different wood tissues; heartwood/mature woodand heartwood/juvenile wood showed 10–20 per cent weightincreases due to linseed oil uptake, compared with 30–50per cent in sapwood/mature wood. Examination by scanning electronmicroscopy confirmed these uptake patterns. The moisture contentafter impregnation was about 5 per cent, irrespective of theLinotech process parameters, tissue type and initial moisturecontent. In conclusion, the impregnation process used here resultsin high levels of well-dispersed linseed oil uptake and shouldfacilitate drying.     

AN EXPERIMENT ON THE SAMPLING OF EARLY THINNINGS

Several subjective and objective methods of sampling the averagevolume per tree in first and second thinnings were tested instands of Sitka spruce (Picea sitcbensis Carr.), Norway spruce(Picea abies Karst.), Scots pine (Pinus sylvestris L.), Corsicanpine (Pinus nigra var. calabrica Schneid.), Douglas fir (Pseudotsugataxifolia Brit.), and European larch (Larix decidua Mill.).Altogether 7,000 thinnings were measured at Fernworthy in Devon,Thetford Chase in Norfolk, Forest of Ae in Dumfriesshire, andKinellar in Aberdeenshire. The subjective methods, consistingof visual estimates and the measurement of groups of trees selectedas appearing representative, tended to give biased results nomore precise than those obtained by the objective methods whichare unbiased. The objective methods tested were random groups,systematic sampling by trees, and systematic sampling by rows.The systematic sampling by rows was the most satisfactory incombining a reasonable degree of precision with simplicity inexecution.     

Species-specific drought effects on flower and fruit production in a Mediterranean holm oak forest

A holm oak forest was exposed to an experimental drought (reductionof 15 per cent soil moisture as predicted for this area forthe next decades by General Circulation Models and ecophysiologicalmodels) during 7 years to elucidate the reproductive responsesof the dominant species Quercus ilex L., Arbutus unedo L. andPhillyrea latifolia L. Soil moisture was partially reduced byplastic strips intercepting rainfall and by ditch exclusionof water runoff. During the period studied, meteorological conditionsand soil moisture were continuously monitored, together withflower and fruit production in the three dominant species. InQ. ilex and A. unedo, flower and specially fruit productionwere strongly correlated with annual rainfall, but not in P.latifolia. The experimental drought reduced flower and fruitproduction in Q. ilex by 30 per cent and 45 per cent, respectively.Reductions in flower and fruit production were not significantin A. unedo and were not observed in P. latifolia. A decreasein production of reproductive structures and the different responseof the species studied to a decrease in water availability couldinduce important changes in the competitive ability of the differentspecies and in the long term in the community species compositionand future distribution of these Mediterranean species.     

Fine root biomass,distribution, and production in young pine-hardwood stands

Patterns of fine root biomass, production, and distribution were estimated for pure stands and mixtures of three-year-old loblolly pine (Pinus taeda L.) with red maple (Acer rubrum L.) or black locust (Robinia pseudoacacia L.) on the Virginia Piedmont to determine the role of fine roots in interference between pine and hardwood tree species. Estimates were based on amounts of live and dead fine roots separated from monthly core samples during the third growing season after planting. Live and dead fine root biomass and production varied by species, but mixtures of loblolly pine and black locust generally had greater fine root biomass and fine root production than pure stands or loblolly pine-red maple mixtures. Hardwood species had greater live fine root biomass per tree in mixtures with pine compared to pure stands. Greater live fine root biomass in pine-locust stands may be attributed to differential utilization of the soil volume by fine roots of these species. For all stands, approximately 50% of live five root biomass was located in the upper 10 cm of soil.     

Effect of half-systematic and systematic thinning on the increment of Scots pine and Norway spruce in Finland

Diameter, height and volume increment of Scots pine (Pinus sylvestrisL.) and Norway spruce (Picea abies (L.) Karst.) stands wereinvestigated in long-term thinning experiments in southern Finland.The measurement period was on average 19 years, and thinningsconsisted of five different treatments: (1) unthinned; (2) selectivethinning from below where thinning intensity was determinedaccording to the number of stems; (3) selective thinning frombelow where thinning intensity was determined according to standbasal area; (4) systematic thinning where corridors were openedat regular intervals in the stand; and (5) half-systematic thinningwhere corridors were opened at regular intervals and the remainingstrips thinned from below, i.e. a combination of selective andsystematic thinning. The selective (basal area) thinning ofScots pine resulted in a volume growth reduction of about 12per cent, but in Norway spruce it resulted in no marked reductioncompared with the unthinned plots. In both tree species, volumeincrement in the half-systematic and selective (basal area)thinning differed only slightly from each other. The systematicthinning resulted in the lowest volume increment. In the systematicthinning, the total yield (m³ ha^–1) somewhat decreasedwith increasing corridor width. In half-systematic thinning,on the other hand, the total yield was not clearly related tocorridor width. A corridor accelerated the diameter incrementof the edge trees. The edge effect progressively diminishedwhen moving deeper into the strip and ended at a distance ofabout 3–4 m from the corridor edge. After the thinning,the height increment first decreased, but later on it recovered.The unthinned plots had more dead trees than the other treatments,but there were no significant differences between the othertreatments. It can be concluded that the prevailing thinningmethod in the Nordic countries, i.e. half-systematic thinning,most probably results in no significant growth and yield losses.     

Heterobasidion annosum: Development of Butt Rot following Thinning in two young First Rotation Stands of Norway Spruce

Severe butt rot caused by Heterobasidion annosum (Fomes annosus)developed in two stands of first rotation Norway spruce on oldagricultural land within 11 years of first thinning. At SiteI (Devon), 11 per cent of thinning stumps and 23 per cent ofclear felled stumps were found to be decayed when examined soonafter the crop was felled at age 37 years. It is estimated thatbetween 4.4 per cent and 6.6 per cent of potential volume waslost on clear felling. Significant butt rot had also developedin a 33-year-old stand of Norway spruce in Site II (Aberdeenshire)11 years after a Scots pine nurse crop was removed. Here, thedisease was found to be widespread on an area of 2 ha, and 73per cent of trees had butt rot. Decay extended 3 m up the stems,and occupied significant areas of the butt. In both cases, thepresence of butt rot in the crops led to premature clear felling,which resulted in additional loss of potential revenue. It seems most likely that the disease became established followinginfection of thinning stumps by airborne spores of the fungus:at Site I, the thinning stumps were not protected whilst atSite II it would appear that a chemical or biological treatmentapplied to the pine stumps failed. The subsequent rapid developmentof the disease was due, in part, to a variety of environmentaland edaphic factors.     

Tree Seed Production and Food Conditions for Rodents in an Oak Wood in Southern England

Seed production and seed losses were monitored in an oak (Quercusrobur) wood in southern England between 1975 and 1988. In additionto acorns, seeds from several large beech (Fagus sylvatica)and sweet chestnut (Castanea sativa) trees which occurred withinthe wood, and from the understorey of hazel (Corylus avellana)trees, were also monitored. The seeds from these four tree speciesare all subject to heavy predation by rodents, as well as otherseed-eaters such as birds and insects. Seed fall tended to be irregular and three years, 1976, 1985and 1987 were considered oak mast years. There were too fewyears with large acorn crops to examine whether resource depletionin these years resulted in poor crops in subsequent years. Therewas no correlation in seed production between the four treespecies which does not agree with one of the predictions ofthe predator satiation theory of masting behaviour. The effectsof weather on seed production were investigated but few significantcorrelations were found. In general the results tended to supportprevious findings. Between 1980 and 1982 a serious outbreakof Tortrix moth caterpillars occurred within the wood and mayhave affected acorn production. A negative relationship wasfound between oak defoliation and acorn production in the subsequentyear. The loss of seeds from the forest floor was initially rapidand in 9 years no seeds survived into the following year andfood conditions were poor for granivores. In 3 of the remaining4 years acorns survived well into spring and early summer providinggood food conditions for forest rodents through to the timeswhen alternative food supplies became available. Although oaktrees contributed most seed energy in good years, the othertree species, especially beech, became important when acornproduction was poor. Predispersal losses due to predators werefrequently high and averaged 80 per cent, 40 per cent, 38 percent and 33 per cent in hazel, sweet chestnut, oak and beechrespectively. On average, hazel nuts tended to fall first, some6 weeks before acorns which tended to be the last seeds to fallof the four tree species. Knopper galls and weeviled acornsfell earlier than sound acorns. A key-factor analysis indicatedthat a failure to mature, predispersal predation and insectinfestation from weevils and Knopper galls contributed equallyto changes in numbers of acorns among years.     

Colonization of Two Nothofagus species by Lepidoptera in Southern Britain

Between 1975 and 1982 a study was made of the invertebrate faunacolonizing two deciduous species of southern beech, Nothofagusobliqua and N. procera, introduced into Britain from South America.Special attention was paid to the folivorous larvae of Lepidopterawhich were sampled at 15 localities in southern England, mostlyin Forestry Commission trial plots and arboreta in Gloucestershire. The literature describing the native insect fauna of Nothofagusin Chile and Argentina is briefly reviewed. Mention is alsomade of the few previous records of lepidopterous larvae observedfeeding on Nothofagus in Britain. The larvae of 81 species Lepidoptera are recorded from Nothofagus.Seventy-eight of these were feeding on the foliage, of which73 were found on N. procera and 62 on N. obliqua, although approximately62 per cent of all the larvae collected were from N. obliqua.Faunal differences between the sites studied are briefly described.Two additional species of cutworm larvae are also reported attackingthe roots of Nothofagus seedlings. The changing lepidopterous fauna on Nothofagus from May untilSeptember is described and discussed. Spring-feeding larvaeof Operophtera brumata (L.), Agriopis aurantiaria (Hübn.)and Erannis defoliaria (Clerck) comprised 55 per cent of alllarvae collected on the two hosts, and represented between 68per cent and 87 per cent of those larvae in beating samplescollected in late May and early June. Most of the larvae collected were reared to adult in the laboratoryon a diet of Nothofagus leaves. The majority of these are regardedas polyphagus species although 64 are known to have one of thetwo native Quercus as a host-plant, while 24 have been recordedas feeding on Fagus sylvatica. The relevance of these two generaas sources for the Lepidoptera fauna colonizing Nothofagus isdiscussed. Nothofagus obliqua and N. procera are shown to have acquireda substantial lepidopterous fauna since their introduction intoBritain near the beginning of this century, although most ofthe trees sampled were less than 25 years old. These two speciesof Nothofagus may be vulnerable to defoliation by several speciesof caterpillar, especially if planted as monocultures in areaswhere oak and beech are plentiful. However, their surprisinglylarge insect fauna may be seen to have some value for natureconservation purposes.     

Ecology, history and silviculture of Scots pine (Pinus sylvestris L.) in western Norway - a literature review

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.     

Wind and snow damage in a thinning and fertilization experiment in Picea abies in southern Sweden

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.     

Integration of water transport pathways in a maple tree: responses of sap flow to branch severing

? It has been known for a long time that sectored and integrated patterns of vascular systems exist in different species and even within the same tree, depending on its age and history. However, very few publications consider the topology of the vascular pathways between roots and branches.

? Some results on this important aspect of the vascular system are presented in this paper. They have been obtained with adult maple trees by directly studying the water movement in the stem and root xylem with the heat field deformation (HFD) method for sap flow measurements.

? Multi-point HFD sensors were installed at different heights of a Norway maple tree (Acer platanoides L.) along its stem axis. Single-point HFD sensors were installed in three small lateral roots of another sample maple. Experimental treatments (branch severing) triggered changes in sap movement in the stem and root sapwood.

? The sample trees belong to the group with an integrated transport system (“integrated pipes”), sharing stem space on both sides of the tree to supply two large parts of the crown with water from each root sector. Nevertheless, conducting pathways had their autonomy for axial transport and the pipe model theory describes the vascular system of the studied trees well. Thus, the integration of axial transport in the stem xylem should presumably occur through the cross-grained network of axial vessels.

     

The Dependence of Quercus robur and Q. petraea Seeding on Cotyledon Potassium, Magnesium, Calcium and Phosphorus during the First Year of Growth

Acorns collected from a range of Quercus robur L. and Q. petraea(Matt.) Liebl. populations were germinated and grown in an unheatedgreenhouse using a standard commercial compost. Total seedlingdry weight did not increase until the end of the growing season,with Q. robur and Q. petraea seedlings showing mean dry weightincreases of 211 per cent and 414 per cent respectively. Oakseedlings appear to depend upon cotyledon reserves of carbohydrate,P, K and Mg during most of the first year of growth, but relyon external sources of Ca. Seedlings become independent of thecotyledons at the end of the first growing season.     

Biomass equations for seven different tree species growing in coppice-with-standards forests in Central Germany

With an increasing demand of sustainable raw materials for bioenergy use, coppicing as management approach to increase the biomass production of forests is becoming of greater importance. This study describes the parameterization of biomass equations for six tree species traditionally used in coppices forests, namely sycamore maple (Acer pseudoplatanus L.), field maple (Acer campestre L.), European ash (Fraxinus excelsior L.), European hornbeam (Carpinus betulus L.), downy birch (Betula pubescens Ehrh.), and common hazel (Corylus avellana L.) growing in coppice-with-standard systems in Lower Saxony, Germany. The parameterization was based on measurements of over 950 trees sampled from two forest sites. The sampled trees were felled and separated into three biomass compartments (stem, coarse branches, and fine brushwood) and weighed on site. The dry weight of sub samples from each compartment was measured. Equations were derived for total aboveground biomass, stem biomass, and crown biomass using regression analyses. We either used diameter at breast height as single independent explanatory variable or in combination with tree height. Biomass production of stump sprouts and generatively grown stems was compared for ash and sycamore maple. In the same age classes, it was found that ash stump sprouts had a slightly higher production than seed-grown stems. For sycamore maple, no difference was detected.     

Nutrient concentrations in roots, leaves and wood of seedling and mature sugar maple and American beech at two contrasting sites

Differences in sensitivity to soil conditions across tree species and developmental stage are important to predicting forest response to environmental change. This study was conducted to compare elemental concentrations in leaves, stems, and roots of (1) sugar maple (Acer saccharum Marsh.) seedlings vs. mature trees and (2) mature sugar maple vs. mature American beech (Fagus grandifolia Ehrh.) in two sites that differ in soil base saturation and pH. Both sites are located in Huntington Forest, NY, USA; one site (hereafter ‘H’) has higher soil pH and Ca, Mg, and Mn concentrations than the other site (hereafter ‘L’). Sugar maple growth at H (14.8 cm² year⁻¹ per tree) was much greater than at L (8.6 cm² year⁻¹ per tree), but the growth of beech was not different between the two sites. Leaves, roots, and stem wood of mature beech trees and sugar maple seedlings and mature trees were sampled for nutrient analysis. Foliar Ca, K, and Al concentrations were positively correlated with soil elements, but Mn concentrations were negatively correlated. Sugar maple differed more than beech between sites in foliar K and Mn concentrations. Root Mg and P concentrations reflected soil chemistry differences, in contrast to foliar concentrations of Mg and P, which were indistinguishable between the sites. In sugar maple, seedlings differed more than in mature trees in nutrient concentrations in roots, especially for Mg and Mn. Although beech was not as responsive to nutrient availability as sugar maple in foliar and root nutrient concentrations, Ca and Mg concentrations in beech wood were higher in H (52% higher for Ca and 68% higher for Mg), while sugar maple did not differ between sites. Sugar maple regeneration failure on acidic soils in the same region is consistent with our finding that sugar maple seedlings were very sensitive to nutrient availability. This sensitivity could ultimately contribute to the replacement of sugar maple by American beech in regions of low pH and base cations if base cation leaching by anthropogenic deposition and tree harvesting continues.