Tree response to bark harvest: the case of a medicinal species, <i>Garcinia lucida</i>, as source of raw materials for plant-based drug development

Abstract

Objectives: There is a huge demand for medicinal bark in developing countries and this demand is growing fast due to it high market values. To assess the effects of bark functions and tree capacities to recover from various debarking practices, a two-year experiment was conducted and several local harvest practices were tested on Garcinia lucida. Methodology and Results: For each practice, 20 healthy trees were selected and harvested. Tree health was monitored every month and the total bark regrowth was calculated using planimetric techniques. In response to bark removal, G. lucida trees produced stilt-roots, sprouts and bark. Re-growth of bark was the most common strategy developed, with mean values ranging from 80 to 100% of trees. All stumps have developed sprouts, with an average number of 6 shoots per stump. The percentage of bark regrowth varies from 45 to 62% of the initial surface debarked for small trees and from 24 to 37% for large trees. A high rate of bark regeneration was found if narrow strips of bark remained on trees, from which bark was hardly removed from wood during harvest, probably characterized physiologically by a downward sap flow due to poor water supply in trees. Conclusions and application of findings:The study has discussed main findings on the experimental debarking of G. lucida and management implications, which would also apply to other species with the same response to bark stripping as source of raw materials for plant-based drug prospects in developing countries. Bark strip harvesting requires species-specific parameters to make it sustainable, taking into account : (i) the bark regeneration capacity (edge growth), which may allow repeated harvest on the same tree; and (ii) the physiological status (downward sap flow) of the tree at the time of harvest, as decisive factor triggering bark regrowth. Partial bark strip harvesting show good prospects for the implementation of long-term sustainable strip harvesting prescriptions, while sustainable stripping through ring-barking practice is unsuitable. Shoot growth and stilt-root development in G. lucida species allows for other management options than strip harvesting, including coppice management and domestication. However, there are major limitations in using

The use of traditional ecological knowledge in sustainable use and management of plant resource through a community-based and participatory assessment

“…The answers to these questions were compared with available ecological data derived from previous studies (Guedje et al, 2007(Guedje et al, , 2016 and field studies conducted in parallel with this survey.…”

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

“…The results of this study indicated that peeling off pieces of bark with a machete yielded more bark mass than hammering on the tree with a stick. Bark mass values for ring-barked trees were higher than those for partially debarked trees; however, this practice has been proved in previous study (Guedje et al, 2016) to lead to high tree mortality, rendering this practice unsuitable for bark stripping as a method of long-term bark harvesting. Another practice expecting to provide high yield of bark harvested was felling tree at 1 m above ground, something not done in this investigation.…”

“…Another practice expecting to provide high yield of bark harvested was felling tree at 1 m above ground, something not done in this investigation. However, flowering and fruiting processes, as well as productivity would completely be suppressed in that case, although the high sprouting capacity of stumps gave the tree a greater chance to reproduce in a vegetative way in natural stands and suggested that this species could be cloned (with desirable "genetic" characteristics or qualities such as the thickness of the bark) and easily brought into domestication or cultivation (Guedje et al, 2016). Bark mass obtained per G. lucida tree increases with stem diameter.…”

“…Bark regrowth patterns, expressed as a percentage of re-growth area, varied between harvest methods with highest values recorded for peeling off 1/3 of the stem circumference. Guedje et al (2016) have found that a high rate of bark-regrowth was found on trees that bark has been hardly removed (narrow strips of bark tissues remained on stem wood), due physiologically or intrinsically, to the predominance of a downward sap flow and poor water supply. Furthermore, when trees were peeling off with machete, narrow strips of bark tissues, which always remained on stem wood, allowed for sap flow to the roots, thereby contributing substantially to tree stability, as well as serving to protect the stem from insect or pathogen attack, and triggering bark regeneration.…”

“…These authors recommended that repeat harvesting should be done only if the bark has re-grown since the previous harvest (harvesting from the alternate quarters from any previous stripping) and the tree is otherwise healthy. Previous study has discussed the main findings on the experimental debarking of G. lucida and found that bark strip harvesting requires species-specific parameters to make it sustainable, taking into account: (i) the bark regeneration capacity (edge growth), which may allow repeated harvest on the same tree; and (ii) the physiological status (downward sap flow) of the tree at the time of harvest, as decisive factor triggering bark regrowth (Guedje et al, 2016). Partial bark strip harvesting has shown good prospects for the implementation of longterm sustainable strip harvesting prescriptions.…”