Ekologiczne konsekwencje hodowli drzew w różnym zagęszczeniu II. Produkcja i alokacja biomasy, retencja biogenów

The main goal of this review was to characterize ecological consequences of growing trees at variable stand densities. Increasing stand density results in rising competition among trees in their below− and above− ground parts, leads to changes in stand structure (DBH, height, crown width and length, crown ratio, tree slenderness, branch diameters and length) and thus modifies biomass partitioning and may influence stand productivity. Trees grown at higher density compete more intensely for limited resources such as space, light, water and nutrients, than in those grown at wider spacing. In general, total tree biomass accumulation is higher in more dense stands and in less dense stands a higher proportion of biomass is allocated to coarse roots. Moreover, stand density may alter foliage distribution within the crowns. For stands grown at higher tree density, leaf area index (LAI) may increase and thus influence stand productivity, however LAI is closely related to light requirements and succession status of the species. Because stand density may simultaneously modify macro− and micronutrient concentration in different tree tissues and biomass partitioning, it may lead to distinct changes in the nutrient balance of the forest ecosystem. For example, a considerable pool of stand mineral elements (including carbon) is allocated to roots that are not subjected to traditional stand management. Therefore, manipulation of stand density leading to higher biomass allocation to roots may increase carbon sequestration in forest ecosystems.