Allometric models for non-destructive estimation of dry biomass and leaf area in Khaya senegalensis (Desr.) A. Juss., 1830 (Meliaceae), Pterocarpus erinaceus Poir., 1804 (Fabaceae) and Parkia biglobosa, Jack, R. Br., 1830 (Fabaceae)

Abstract

Key messages: Measuring biomass and leaf area using non-destructive methods is of great interest to avoid plant degradation. These data are necessary for biomass allocation and estimation of carbon distribution in trees using functional and structural growth models such as GREENLAB. Abstract: Organ biomass and leaf area are important parameters in plant physiology and production. They are used in structural and functional plant models to simulate tree architecture but are difficult to determine rapidly. Using stem length and internode diameter and leaf length and width to estimate them is a rapid, non-destructive field approach. We used the method on Khaya senegalensis, Pterocarpus erinaceus and Parkia biglobosa in Côte d'Ivoire. Internodes and leaves of the three species were sampled in 2019 and 2020 on three categories of axis in the architecture of individuals of different ages to maximize size variability. All statistical relationships found in the linear, logarithmic, polynomial and power models used to estimate the dry biomass of organs and leaf area were significant in all three species (P = 0.0001). The best models were obtained with the logarithmic transformation of the data. Three equation (linear, power and polynomial) were sufficient to estimate internode dry biomass (IDM), leaf dry biomass (LDM) and leaf area (LA) from the dimensions of the internodes (Volume: VL) and leaves (rachis length: RCL, number of primary leaflets: NLt, length: LLtL and width: LLtW of the largest primary leaflet in Khaya senegalensis and Pterocarpus erinaceus, then number of secondary leaflets: NSeLt, length: LSeLtL and width: LSeLtW of the largest secondary leaflet in Parkia biglobosa). In the field, the scientist will therefore make a choice according to his convenience among these proposed models. The best relationships between the measured organ dimensions and estimated parameters were defined by the following equations: IDM = 0.45*VL + 0.02, LDM = 1.07*NLt*LLtL*LLtW-2.74 and LA = 0.83*NLt*LLtL*LLtW or LA = 0.08*[NLt*LLtL*LLtW]2 + 1.13*[NLt*LLtL*LLtW]-0.27 for Khaya senegalensis; IDM = 1.15*VL0.26, LDM = 0.71*RCL*LLtL*LLtW-1.64 and LA = 0.74*NLt*LtL*LtW + 0.15 or LA = 0.03*[NLt*LLtL*LLtW]2 + 0.65*[NLt*LLtL*LLtW] + 0.23 for Pterocarpus erinaceus then IDM = 1.45*VL0.39, LDM = 0.23*[NSeLt*LSeLtL*LSeLtW*NLt]2–0.4*[NSeLt*LSeLtL*LSeLtW*NLt]-0.11 and LA = 1.81*[NSeLt*LSeLtL*LSeLtW*NLt]0.65 for Parkia biglobosa. This method can be applied to estimate the organ biomass and leaf area of species of the same family as the target species in an agroforestry system.