Leaf litter turnover in monodominant forest of the marcescent palm Lodoicea maldivica

Abstract The palm Lodoicea maldivica exhibits marcescence, with dead leaves remaining attached to the trunk for an extended period. We studied leaf litter dynamics in Lodoicea forest to explore the possible significance of marcescence in this species. We estimated litter production and the standing crop of leaf litter hanging from trees and on the forest floor, and also the standing crop of leaf litter in stands of the endemic trees Martellidendron hornei and Deckenia nobilis. The decomposition of four types of leaf litter (newly dead Lodoicea, old but still hanging Lodoicea, Deckenia and Martellidendron) was studied using litter bags set out on the forest floor. Compared to other tropical forests, all species had very low litter N and P concentrations, while total standing crops of litter were exceptionally high (24.0, 22.3 and 16.7 t dry weight ha⁻ ¹ for Lodoicea, Deckenia and Martellidendron, respectively). Forty-six percent of Lodoicea litter was still attached to trees. Decomposition of all litter types was very slow, with mean annual decomposition constants (k values; y⁻ ¹) of 0.41 for new Lodoicea, 0.37 for old Lodoicea, 0.25 for Deckenia and 0.47 for Martellidendron. Decomposition varied significantly amongst litter types (P < 0.001) and with location on the forest floor, reflecting variation in moisture conditions. Because of funneling, hanging leaves are regularly irrigated with water, while leaves on the forest floor are often dry. We suggest that marcescence represents another trait enabling Lodoicea to grow in extremely nutrient-poor soils.