Strategies towards sustainable bark sourcing as raw material for plant-based drug development: a case study on <i>Garcinia lucida</i> tree species

Abstract

Guedje et Tchamou., J. Appl. Biosci. 2017 Strategies towards sustainable bark sourcing as raw material for plant-based drug development: a case study on Garcinia lucida tree species 11513Journal of Applied Biosciences 115: 11502-11512 ISSN 1997-5902 Strategies towards sustainable bark sourcing as raw material for plant-based drug development: a case study on Garcinia lucida tree species ABSTRACT Objectives: To appraise the amount of sustainable bark stripped and time to complete bark recovery as basis for sourcing of raw materials for plant-based drugs Methodology and Results: A two-year experiment was conducted and several local harvest practices were tested on Garcinia lucida (named Essok in Boulou language). For each harvest method, 20 healthy trees were selected and harvested. Tree health was monitored every month and the total bark regrowth was calculated using planimetric techniques. The mean bark mass was 2.54 kg/tree (range, 0.5-15 kg/tree; SD, 2.40; n=80) and increased with bark thickness, ranging from 1.28 kg tree -1 (0.4-0.8 cm thin) to 4.38 kg tree -1 (1.2 -1.8 cm thick). The mean rate of bark regeneration was 787±601 cm²/tree/year (range, 452±166-1870±1042 cm²/tree/yr; n=53) and positively correlated to harvest method (p < 0.01) and surface debarked (p < 0.05).Standard Deviation values were higher, suggesting that each tree had its proper bark growth rate patterns, and that bark regrowth process may be tree-specific and strongly correlated to intrinsic factors. Conclusions and application of findings: Peeling off pieces of bark using a machete and debarking over 1/3 of the stem circumference at breast height, once every 3 years for small trees or every 5 years for large trees, has been found to be the best harvest method for G. lucida species. This is to tackle the challenge of availability of raw material and harvest sustainability. As the increased trade and processing of bark has shifted from subsistence use to large-scale commercial use, posing a threat to supply of raw material and species conservation, sustainable harvesting methods should constitute important tools of the guidelines on good collection practices for medicinal plants that would help to ensure safety and quality at the first and most important stage of the harvest of medicinal plants. This study has provided information on the species-specific bark harvest prescriptions to assist in developing such guidelines, thereby promoting the processing and trade of the most valued medicinal species for plant-based drug development in Africa.

Sustaining Medicinal Barks: Survival and Bark Regeneration of Amphipterygium adstringens (Anacardiaceae), a Tropical Tree under Experimental Debarking

“…Regarding the debarking prescriptions, although the intermediate treatment (50% of the stem bole) was the best for A. adstringens bark regeneration in both sexes, the most intensive harvest followed in order of importance (75%). These results agree with other investigations [14,40,61] in which a positive correlation between the intensity of debarking and the regeneration rate was suggested, whereas Pandey and Mandal [18] and Mariot et al [48] pointed to an opposite pattern. As Romero [58] suggested, it is feasible that after severe damage the hormonal activity stimulated by the physiological stress suffered by the plant will increase in order to restore hydraulic conductivity and close the wound as soon as possible, thus decreasing the risk of vulnerability to the attack of pests and diseases.…”

“…In this study we present a coupled two-way interaction between cutting season:debarking treatment and sex:diameter category, both of which have a positive effect on A. adstringens bark regeneration. These results contrast with other studies because these only analyzed the simple effect of some variables (tree diameter, debarking treatment, cutting season, light intensity, site quality) over the bark regeneration capacity [5,6,13,14,16,17], with some exceptions [48,61]. Observed interactions indicate A. adstringens bark regeneration can be improved by harvesting during the wet season at a 50% harvest intensity treatment.…”

“…Nonetheless, it does not coincide with the amount of bark removed by tree, because there seems to be a tolerance gradient, where, on the one hand, partial debarking with machete favors the survival rate [49], whereas, on the other hand, the bark harvest from 50 to 100% of the stem bole shows a contrary pattern [6,16]. In consequence, results suggest both the capacity of bark regeneration as well as survival are dependent on the species [5] and individuals [61], and in the case of A. adstringens also the sex.…”

“…Part of this group of species, Adansonia digitata L., exhibits a mechanism of cellular compartmentalization similar to that of A. adstringens [59], which positively impacts on a high rate of survival and regeneration [60], as reported in the present study. In contrast, most medicinal bark species in the world have mortality rates close to 100% and much slower bark regeneration when harvest involves the removal of the vascular cambium [47,50,55,61]. Arguably, the high tolerance displayed by A. adstringens may be due to the combination of various physiological, morphological and anatomical factors of the bark [62].…”

“…As we indicated previously, debarking of A. adstringens trees during the wet season positively influenced the wounds closure of both sexes, similar to the results of Solares et al [19] for the same species, as well as those of Delvaux et al [39] for five tropical trees in Africa. In fact, it has been suggested that conserving moisture from the exposed surface is the main factor for successful regeneration [56,57,61]. For the temperate forest tree Tilia sp.…”