Energy content of plant organs and population cohorts in Moringa peregrina: concepts for species conservation management in arid regions

Abstract

Conservation management and sustainable use of Moringa peregrina are needed to overcome overexploitation coupled with potential environmental changes. This study demonstrates the energy dynamics of M. peregrina, how stored energy influences species persistence amidst environmental challenges, and the importance of energy reserves in the resilience of the species population. Field, greenhouse, and lab experiments were conducted at the levels of population cohorts, plant organs, seeds, and seedlings to demonstrate the relationship between energy content and the persistence of the species. Seedlings and juveniles stored around 12,000 joule/g in roots, while uncoppiced adults stored about 9,000 joule/g in stems, and coppiced adults stored 1,800-4,000 joule/g in lignotubers. In adult trees, the number of sprouting stems is correlated with the energy content in lignotubers. Over the ten years of seed storage, a rapid rate of energy depletion was observed, ranging from 16,821 to 5,059 joule/g, which is associated with decreased germination and viability. The energy content in two-month-old seedlings varied from 240 to 800 joule/seedlings under 200 and 800 mm rainfall, respectively. The unstable population structure could be ascribed to the depletion of stored energy in lignotubers following uncontrolled coppicing and the rapid depletion of seed energy, which hinders the population resilience.