7 research outputs found
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Biomass partitioning and growth efficiency in four naturally regenerated forest tree species
Current forest growth models and yield tables are almost exclusively based on data from mature trees, reducing their applicability to young and developing stands. To address this gap, young European beech, sessile oak, Scots pine and Norway spruce trees approximately 0 to 10 years old were destructively sampled in a range of naturally regenerated forest stands in Central Europe. Diameter at base and height were first measured in situ for up to 175 individuals per species. Subsequently, the trees were excavated and dry biomass of foliage, branches, stems and roots was measured. Allometric relations were then used to calculate biomass allocation coefficients (BAC) and growth efficiency (GE) patterns in young trees. We found large differences in BAC and GE between broadleaves and conifers, but also between species within these categories. Both BAC and GE are strongly age-specific in young trees, their rapidly changing values reflecting different growth strategies in the earliest stages of growth. We show that linear relationships describing biomass allocation in older trees are not applicable in young trees. To accurately predict forest biomass and carbon stocks, forest growth models need to include species and age specific parameters of biomass allocation patterns
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Individual biomass factors for beech, oak and pine in Slovakia: a comparative study in young naturally regenerated stands
Biomass conversion and expansion factors (BCEF) which convert tree stem volume to whole tree biomass and biomass allocation patterns in young trees were studied in order to estimate tree and stand biomass in naturally regenerated forests. European beech (Fagus sylvatica L.), Sessile oak (Quercus petraea (Mattuschka) Liebl.) and Scots pine (Pinus sylvestris L.) stands were compared. Seven forest stands of each species were chosen to cover their natural distribution in Slovakia. Species specific BCEF are presented, generally showing a steep decrease in all species in the smallest trees, with the only exception in the case of branch BCEF in beech which grows with increasing tree size. The values of BCEF for all tree compartments stabilise in all species once trees reach about 60-70mm diameter at base. As they grow larger, all species increase their allocation to stem and branches, while decreasing the relative growth of roots and foliage. There are, however, clear differences between species and also between broadleaves and conifers in biomass allocation. This research shows that species specific coefficients must be used if we are to reduce uncertainties in estimates of carbon stock changes by afforestation and reforestation activities
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Biomass functions and expansion factors in young Norway spruce (Picea abies [L.] Karst) trees
Roots, stems, branches and needles of 160 Norway spruce trees younger than 10 years were sampled in seven forest stands in central Slovakia in order to establish their biomassfunctions (BFs) and biomassexpansionfactors (BEFs). We tested three models for each biomass pool based on the stem base diameter, tree height and the two parameters combined. BEF values decreased for all spruce components with increasing height and diameter, which was most evident in very young trees under 1 m in height. In older trees, the values of BEFs did tend to stabilise at the height of 3–4 m. We subsequently used the BEFs to calculate dry biomass of the stands based on average stem base diameter and tree height. Total stand biomass grew with increasing age of the stands from about 1.0 Mg ha−1 at 1.5 years to 44.3 Mg ha−1 at 9.5 years. The proportion of stem and branch biomass was found to increase with age, while that of needles was fairly constant and the proportion of root biomass did decrease as the stands grew older
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Replacing Norway spruce with European beech: a comparison of biomass and Net Primary Production patterns in young stands
An alteration of species composition in temperate forests – both managed and natural - is one of the expected effects of environmental change. Present forest tree species ranges will be altered by changing environmental conditions. By a combination of continuous and destructive sampling, we compared biomass stocks and annual NPP in naturally regenerated stands of Norway spruce and European beech. We purposely selected a site where future environmental conditions are predicted to favour beech over presently dominant spruce. We found no difference in overall productivity, but biomass allocation differed significantly between the two species. Beech allocated more assimilates to stem and roots than spruce. There was no significant difference between the species in NPP of the fast turnover biomass pool comprising foliage and fine roots. Maximum height growth occurred about a month earlier than in spruce, potentially changing the timing of carbon (C) flow into the soil pools. We show that the replacement of spruce by beech will result in changes in forest biomass allocation and in alterations of belowground C cycle. Such changes will affect forest ecosystem function by modifying the magnitude and timing of certain C fluxes, but also by potentially changing the species composition of forest biota dependent on them
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Belowground biomass functions and expansion factors in high elevation Norway spruce
Biomass allocation to above- and belowground compartments in trees is thought to be affected by growth conditions. To assess the strength of such influences, we sampled six Norway spruce forest stands growing at higher altitudes. Within these stands, we randomly selected a total of 77 Norway spruce trees and measured volume and biomass of stem, above- and belowground stump and all roots over 0.5 cm diameter. A comparison of our observations with models parameterised for lower altitudes shows that models developed for specific conditions may be applicable to other locations. Using our observations, we developed biomass functions (BF) and biomass conversion and expansion factors (BCEF) linking belowground biomass to stem parameters. While both BF and BCEF are accurate in belowground biomass predictions, using BCEF appears more promising as such factors can be readily used with existing forest inventory data to obtain estimates of belowground biomass stock. As an example, we show how BF and BCEF developed for individual trees can be used to estimate belowground biomass at the stand level. In combination with existing aboveground models, our observations can be used to quantify total standing biomass of high altitude Norway spruce stands