Measurement and modelling litter biomass and leaf area index using allometry in a Beech-Hornbeam stand in the mid-elevation of the Hyrcanian region, Iran

Litter biomass and leaf area index (LAI) are two important attributes which play crucial roles on the biological processes which impact forest productivity, including photosynthesis, water and nutrient cycles. Litter biomass of a Beech-Hornbeam stand located at the mid-elevation of the Hyrcanian region (Forest management plan of Neka-Zalemroud, district five) was measured using 27 litter traps in a one-year period. In addition, LAI was determined by means of gravimetric method, applying a leaf area meter as well as a metal pipe cutter. A regression model was parameterized to predict the values of litter biomass and LAI using a set of allometric parameters including density, basal surface area, trunk volume, and crown area / volume. Total litter biomass and leaf biomass were determined to be 5.472 and 3.707 ton per hectare per year, respectively. Mean LAI was measured to be 7.5, and 7.7 using leaf area meter, and metal pipe cutter, respectively. The analysis shows that area and volume of crown presents a greater coefficient of determination and smaller root mean squared error than other allometric parameters, indicating the best predictors regarding litter biomass and LAI. Stand-specific models of Beech-Hornbeam were detected more robust than species-specific models of Beech and Hornbeam. Furthermore, species-specific models of Hornbeam were significantly less robust than those specified for Beech