Aboveground biomass allocation and accumulation in a chronosequence of young Pinus sylvestris stands growing on a lignite mine spoil heap

It is not clear to what extent trees growing on anthropogenic sites change their growth and biomass allocation to different organs. We assessed the aboveground biomass in a chronosequence of six Scots pine monocultures (between 6 and 20 years old) to examine how precisely the site-specific or control allometric equations may reflect the value of biomass accumulation and allocation in stands growing in harsh site conditions on the overlayer spoil heap made as a result of opencast brown coal mining. The site is characterized by poor edaphic and water conditions and nutrient deficiency. The control equations were developed from Scots pine stands growing on post-agricultural lands in the close vicinity of the spoil heap. We found that equation type significantly influenced results of predicted biomass accumulation for all biomass components studied (although results were only marginally significant for total aboveground biomass, P=0.08). Total aboveground biomass in younger stands (6-9 years old) estimated using site-specific equations was >40% higher and for older stands (17-20 years old) from 7 to 27% lower than estimated using equations developed for the control sites. Our study revealed that under harsh environmental conditions in spoil heaps, biomass of young Scots pine stands significantly differ from values calculated based on control equations developed for more fertile soils with better water conditions in the same region. The control biomass equations may not be suitable to estimate biomass accumulation in stands growing on infertile habitats with poor water conditions, if the control equations are developed for nearby stands but growing under better site conditions.