摘要

We studied the chronosequence of six Scots pine (Pinus sylvestris L.) plantations (6-, 9-, 11-, 15-, 17-, and 20-years-old) to examine the changes in leaf area index (LAI) over stand age. The study site was located on a mine spoil heap (outer dumping ground) in the Belchatow lignite open-cast mining district (central Poland). The main goal of the study was to analyze LAI changes over stand age in a chronosequence of young Scots pine stands and to test the relationship between LAI estimates derived from a LAI-2000 Plant Canopy Analyzer and site-specific allometric equations. In addition, we tried to determine whether LAI estimated by a LAI-2000 PCA can be used to accurately estimate forest biomass. We hypothesized that LAI-2000 PCA underestimates LAI of the stands, and that stand age (and linked stand parameters) may influence the range of the hypothetical underestimation due to changes in biomass allocation. Our study revealed that LAI was highly dependent upon stand age and tree density (p<0.0001) regardless of the way how LAI was determined. Moreover, we found that LAI estimated by LAI-2000 PCA significantly correlates with stand biomass per area; the highest coefficients of determination were found for total aboveground biomass, aboveground woody biomass, and stem biomass. This means that data obtained by LAI-2000 PCA are good predictors of stand biomass in the young stages of stand development. In contrast to our prior assumption, the results showed that LAI-2000 PCA overestimates leaf area index. The relative differences between the values obtained with LAI-2000 and those calculated on the basis of the site-specific allometric equations increase with age. This may reflect changes in crown architecture over age caused by enlarging tree dimensions and overcrowding of trees leading to deterioration of light conditions inside the canopy.

  • 出版日期2008