Variation in seedling predation and herbivory in Prunus africana in the Kakamega Forest, Kenya

Abstract

SUMMARY Variation in seedling predation and herbivory was studied in three Prunus africana adult trees in the Kakamega forest, Kenya. Percentage predation varied inversely with percentage herbivory and both changed from one tree to another. Smaller seedlings were more likely to be killed by predators while larger seedlings could only be damaged by herbivores. Although it was hard to predict percentage predation given percentage herbivory, it was possible to predict the likely cause of seedling mortality or damage given a seedling stage. The effects of predation and herbivory on seedling dynamics are also discussed. Résumé On a étudié la variation de la prédation et de l'herbivorie sur les jeunes pousses de trois arbres adultes de Prunus africana, dans la forêt de Kakamega, au Kenya. Le pourcentage de prédation variait inversément par rapport à celui des dommages causés par les herbivores. Les plus petites pousses étaient plus susceptibles d'être attaquées par des predateurs tandis que les plus grandes ne pouvaient être endommagées que par les herbivores. Ces deux pourcentages variaient d'un arbre à l'autre. S'il était difficile de prédire le pourcentage de prédation au su des dommages causés par les herbivores, il était possible de prévoir la cause vraisemblable de mortalité des jeunes pousses ou des dommages selon l'âge de la pousse. On discute des effets de prédation et d'herbivorie sur la dynamique de la repousse.

Effects of bark harvest and other human activity on populations of the African cherry (Prunus africana) on Mount Oku, Cameroon

“…It is most abundant in open forest areas and disturbed habitats (Geldenhuys, 1981;Ewusi et al, 1992;Fashing, 2004). Tsingalia (1989) observed seedlings along forest margins where he suggested predation rates were lower, while Ndam (1998) found most seedlings in fallow fields or forest gaps. Thus, P. africana appears to be a light-demanding, secondaryforest species.…”

Enhanced seed dispersal of Prunus africana in fragmented and disturbed forests?

“…The monoecious tree reaches 25-40 m in height producing small white flowers in elongated clusters and purple fleshy fruits (mean ± 1 SD, length: 9.3±1.1 mm, width: 7.3±0.8 mm, height: 7.0±0.8 mm, mass: 0.4±0.1 g, N=21) with one seed (length: 8.1±0.7 mm, width: 6.1±0.4 mm, height: 5.5±0.5 mm, mass: 0.15±0.05 g, N=30). Seeds germinate well under shady conditions, but saplings require light gaps for further growth (Tsingalia 1989). Annual height increment of P. africana seedling is quite variable (<3-8 cm/ year) depending on light conditions (Hall et al 2000).…”

Fine-scale spatial genetic dynamics over the life cycle of the tropical tree Prunus africana

“…Comparable to many other tree species (Petit and Hampe, 2006), recruitment rates of young P. africana seedlings to older saplings are low, potentially because of high light requirements (Tsingalia, 1989;Tesfaye et al, 2002). Thus, multiple mortality factors, both random and non-random, may lead to the observed thinning and drive the initial decrease in SGS.…”

“…Secondary seed dispersal seems to be neglectible in the species, as experiments with thread-marked P. africana seeds did not record any caching, but only later predation of seeds (Svd Gönna and M Melcher, personal communication). Survival to the sapling stage is very low, potentially because of high light requirement as well as strong seed predation and seedling herbivory (Tsingalia, 1989;Tesfaye et al, 2002).…”