Decadal forest mensuration cycle significantly underestimates net primary production in dense young beech stands

The early development of naturally regenerated forest stands is highly dynamic and includes rapid shifts in productivity and mortality. To characterise the growth dynamics in the initial decades, we assessed aboveground biomass stocks (Sab), aboveground biomass productivity (DPab), and aboveground biomass mortality (DMab) in five naturally regenerated European beech stands located in the Inner Western Carpathians. We developed allometric models for aboveground biomass compartments based on a sample of 262 trees. We also established five circular sampling plots within each stand and, for 15 years, carried out annual measurements of stem diameter at the base and height for all trees within the sampling plots. We then utilised the allometric models to calculate annual biomass accumulation in aboveground biomass compartments on an area basis. Our findings show that, despite the declining contribution of foliage to the total aboveground stock, about a quarter of annual net primary production in young beech stands enters the dead biomass pool due to leaf fall and tree mortality. The growth dynamics and biomass allocation patterns of young beech forests necessitate the development of specific allometric models to describe their growth and carbon capture processes

Construction and scientific implementation of mathematical models for tree compartments of broadleaved trees in growth stages of seedlings and young stand

Importance of precise estimation for tree biomass in forests has been continuously increasing. Regarding to the climate change, scientists have started to quantify all tree components not only in terms of energetic utilization but also for carbon stock estimation. Increasing relevance of biomass models for young trees relates to expanding area of young forest stands during the last period due to decay of old forests often caused by disturbances (especially: windstorms, outbreaks of bark beetles, drought episodes, and forest fires). Models for biomass stock estimations constructed for stands with age to 10 years are rare and usually are focused on aboveground tree parts. Thus, this work aims at filling knowledge gaps in this field. Its main objectives are: 1) construction of regression models applicable for estimation of dry mass in the particular tree components (i.e. stem, branches, foliage, roots) for young stands of some broadleaved species, 2) implementation of regression models for calculation of biomass conversion and expansion factors (BCEF), allocation coefficient, growth efficiency and leaf area index (LAI) and their inter-specific comparison, 3) utilisation of allometric relations for estimation on forage potential for ruminating ungulate game (i.e. browsing and stripping). To make up the models, destructive tree sampling will be implemented. The sample trees will be excavated, separated into tree components, dried for constant weight and weighed. Log-transformed relationships will be used for construction of regression models

Construction and scientific implementation of mathematical models for tree compartments of broadleaved trees in growth stages of seedlings and young stand

Importance of precise estimation for tree biomass in forests has been continuously increasing. Regarding to the climate change, scientists have started to quantify all tree components not only in terms of energetic utilization but also for carbon stock estimation. Increasing relevance of biomass models for young trees relates to expanding area of young forest stands during the last period due to decay of old forests often caused by disturbances (especially: windstorms, outbreaks of bark beetles, drought episodes, and forest fires). Models for biomass stock estimations constructed for stands with age to 10 years are rare and usually are focused on aboveground tree parts. Thus, this work aims at filling knowledge gaps in this field. Its main objectives are: 1) construction of regression models applicable for estimation of dry mass in the particular tree components (i.e. stem, branches, foliage, roots) for young stands of some broadleaved species, 2) implementation of regression models for calculation of biomass conversion and expansion factors (BCEF), allocation coefficient, growth efficiency and leaf area index (LAI) and their inter-specific comparison, 3) utilisation of allometric relations for estimation on forage potential for ruminating ungulate game (i.e. browsing and stripping). To make up the models, destructive tree sampling will be implemented. The sample trees will be excavated, separated into tree components, dried for constant weight and weighed. Log-transformed relationships will be used for construction of regression models

Quantifying carbon in dead and living trees; a case study in young beech and spruce stand over 9 years

In Slovakia, the contribution of young stands to the total forest area has been increasing in the last decade. However, scientific attention to these stands was previously very sparse and they were usually not included in local and country carbon stock estimates. Therefore, we focused on the calculation of tree biomass and necromass in young beech and spruce stands as well as on their development during the period of nine years (aged from 4 to 12 years). For the calculation, we implemented allometric equations using tree diameter and height as independent variables. The results showed very dynamic changes in biomass (carbon) stock. Specifically, tree biomass increased in the period of 9 years from about 2,000 g to 15,000 g (i.e. cca 1,000 to 7,500 g of carbon) per m2 in beech, and from 4,500 to 12,000 g (cca 2,300 to 6,000 g of carbon) per m2 in the spruce stand. At the same time, the amount of biomass (fixed carbon) was only slightly larger than the accumulated quantity of necromass (carbon loss from living trees). It means that a large portion of carbon was allocated to necromass. We found that not only the foliage fall but also the mass of dead trees, a result of intensive competition, was an important path of carbon flux to necromass. The results proved that although young forests fix much less carbon in their biomass than old stands, they can represent large carbon flux via annual increment of necromass. This indicates that young stands should not be omitted in forest carbon balance estimates of the country