Leaf phenological traits of the tree fern Cyathea praecincta (Cyatheaceae) in a Brazilian lowland tropical forest

Abstract

Phenological studies are fundamental to our understanding of how the environment can influence plant growth and reproductive processes. Environmental triggers of fern phenology are poorly known. We investigated the leaf phenological traits of the tree fern Cyathea praecincta (Kunze) Domin in a Brazilian lowland tropical forest with a short dry season. We monitored 47 plants over an 18-month period, measuring leaf production, leaf fertility, leaf mortality and the relation of these variables with rainfall and temperature. Data on leaf expansion and lifespan were also presented. Full leaf expansion in C. praecincta took up to 3 months. The production of sterile and fertile leaves showed dissimilar interactions with climate, a common pattern among most tree ferns studied worldwide. Whereas production of sterile leaves of C. praecincta was not influenced by climatic variability, leaf fertility was driven by increasing rainfall. Some fertile plants (30%) produced exclusively fertile leaves and attained full maturity, playing a key role in the maintenance and growth of the population. The estimated leaf lifespan was 17.9±5.89 months. The finding that leaf mortality was driven by decreasing rainfall is in contrast with most tree ferns, which are not influenced by climate. None of the phenological variables was influenced by temperature. We demonstrated that rainfall plays a crucial role on leaf fertility and leaf mortality of C. praecincta in a tropical forest remnant with a short dry season and inversely related rainfall and temperature.