Frankincense tapping reduced photosynthetic carbon gain in Boswellia papyrifera (Burseraceae) trees

Frankincense yield is related to tree size and resin-canal characteristics

“…Moreira et al, 2014). This is also supported by Mengistu et al (2012), who showed that resin production has a higher priority in carbon allocation than stem growth in B. papyrifera. In other studies, however, radial stem growth was positively correlated with the number of resin ducts in the bark of Picea glauca (Alfaro et al, 1997) and with the number of resin ducts in wood of P. taeda (DeAngelis et al, 1986), but negatively in another study in the wood of the same species (Blanche et al, 1992).…”

“…The fact that reducing the leaf area through lopping for livestock feed has a negative impact on frankincense production (Tilahun, 2012) is supportive of this. The reported lack of significant effects of crown leaf area on frankincense yield (Mengistu et al, 2012) may be related to the limited size range (with tree stem diameters between 17 and 22 cm) considered in that study. Since resin is harvested during the dry season, we expect that the extra carbon, stored as starch, serves as a major source for the frankincense production during the dry season (Mengistu et al, 2012(Mengistu et al, , 2013.…”

“…The reported lack of significant effects of crown leaf area on frankincense yield (Mengistu et al, 2012) may be related to the limited size range (with tree stem diameters between 17 and 22 cm) considered in that study. Since resin is harvested during the dry season, we expect that the extra carbon, stored as starch, serves as a major source for the frankincense production during the dry season (Mengistu et al, 2012(Mengistu et al, , 2013. Additionally, the presence of bark chlorophyll (Girma et al, 2013) suggests that bark photosynthesis could also contribute to the frankincense production in the dry season.…”

“…Blanche et al (1992), also reported that resin flow and radial growth were unrelated for P. taeda. Mengistu et al (2012), speculated that B. papyrifera trees have the strongest demands for assimilates posed by maintenance respiration, foliage establishment and resin production and that stem growth has a low priority when compared to frankincense production. Such trade-offs in carbon-allocation pattern to different sinks may pose constraints on plants in a stressed environment (Herms and Mattson, 1992;Kleczewski et al, 2010), and possibly decouples a direct link between radial stem growth and frankincense yield.…”

“…In addition, improper tapping is frequently mentioned as one of the reasons for the decline of tree numbers within the extant populations (Abiyu et al, 2010;Eshete et al, 2012a). From earlier studies, it is evident that tapping for frankincense reduces reproductive effort Mengistu et al, 2012) and exposes the trees to insect attack (Abiyu et al, 2010). Seeds from tapped B. papyrifera trees also showed lower germination success as compared to seeds from untapped trees Eshete et al, 2012b).…”