Occupation spatiale deCyathea muricataWilld. (Cyatheaceae) en forêt dense humide guadeloupéenne. II—À l'échelle de la population

Abstract

A hstmct.-A study of the spatial occupation of Cyathea muricata Will d. has been made in Guadeloupe in the tropical rain forest. We have considered the occupied space at the level of the population and in the community. A part of this study emphasises, indeed, the importance of the occupied space by the plant in their interactions with the rest of the vegetation and notably in the phenomenons of inter-specific competition. The cartography of all the plants higher than 130 em of height and all the ferns in a given plot allows the study of the population and its interactions with the rest of ligneous plants. The ferns lower to 130 em are aggregated; the other ones are randomly distributed in the plot. Even if tree-ferns haven't got impact on the total density of ligneous plants, they seem to slow down their growth. So we supposed that tree-ferns give off, in their environment, some toxic substances: it's a phenomenon of allelopathy.

The hare, tortoise and crocodile revisited: Tree fern facilitation of conifer persistence and angiosperm growth in simulated forests

“…Tree ferns do not develop structural tissues on their trunks through secondary growth; thus, they cannot significantly increase the diameter of their trunks (although a relatively small cone of dense adventitious rhizoids frequently develops at the base of the trunk). It is not known how long after sporophyte development the trunk is produced, and by the time trunk height reaches 0.5 m, tree ferns can produce full‐size fronds (Brock et al, ; Bystriakova et al, ; Prugnolle, Rousteau, & Belin‐Depoux, ). Furthermore, age‐growth data are difficult to obtain for tree ferns as, similar to monocotyledons, tree fern structures leave few indications of an individual's age (Brock et al, ).…”

“…Implementing and parameterizing a model to represent tree ferns is challenging because growth is not associated with an increase in diameter, but with increase in height as with palms (Uriarte et al, ). Furthermore, height increment is not associated with an increase in canopy dimensions (at least above heights of 0.5 m tall; Prugnolle et al, ), and tree fern individuals should persist for realistic life spans. The failure to represent tree ferns’ fundamental characteristics likely explains why previous models have overestimated tree fern growth, underestimated their relative prevalence and have not captured the influence of a tree fern understorey on other forest species.…”

Tree Fern Cyathea lepifera May Survive by Its Phytotoxic Property

“…The spatial occupation of Cyathea muricata (Cyatheaceae) in tropical forests was investigated in Guadeloupe in the Caribbean, and the tree fern was found to have suppressed the growth of other ligneous plants. This phenomenon was assumed to be caused by toxic substances released from the fern into the forest floor [2]. However, the substances have not yet been identified, and how those substances are released into the environment is also unknown.…”

“…However, the substances have not yet been identified, and how those substances are released into the environment is also unknown. fern into the forest floor [2]. However, the substances have not yet been identified, and how those substances are released into the environment is also unknown.…”