Fine Litter Dynamics within the Tree Canopy of a Tropical Cloud Forest

Abstract

Fine litter deposition and decomposition within the upper tree canopy was measured in a neotropical cloud forest to determine the potential nutrient input to epiphyte communities from intercepted tree litterfall. A comparable amount of fine litter passed through the canopy (752 g°m—2°yr—1) as arrived on the forest floor (820 g°m—2°yr—1), but <1% of the biomass and nutrients of this "gross litterfall" was retained within the upper tree canopy. The standing crop of litter in the canopy (°170 g/m2 of branch surface area, 8.8 g/m2 of ground area) is equivalent to only 1% of the standing crop of litter on the forest floor. Measurements of leaf litter attrition (whole leaf loss from branches due to wind and other disturbances) with marked leaves documented that 70% of leaves deposited on branches are lost in the first 2 wk and nearly all are gone in 16 wk. Certain branch characteristics (branch angle, number of epiphyte stems and clumps) appear to affect the amount of litter retained at particular microsites. Decomposition of tethered, dead leaves within the canopy over a 12—mo period was half that of leaves on the forest floor (canopy litter turnover time = 2.8 yr). Assuming that litter accumulation within the canopy is at steady state, the biomass of fine litter retained and decomposed within the canopy was calculated as only 2.0 g°m—2°yr—1 and < 0.02 g°m—2°yr—1 for all nutrients. Nutrient replenishment of epiphyte communities appears to be decoupled from the litterfall pathway, as input from litterfall retained within the canopy is small relative to epiphyte productivity and nutrient requirements reported in other studies.

Root biomass distribution in a moist tropical montane forest

“…small amounts of nutrients within the canopy are derived from intercepted host tree litterfall (Nadkarni and Matelson, 1991). It is likely that the interception of mist, which is a frequency occurrence at our study site, provides a major nutrient flux to the canopy.…”

Distribution, composition, and dispersal of ant gardens and tending ants in three kinds of central Amazonian habitats

“…After the initial structure of the AG is formed, it may grow in complexity, as it is a good site for the deposition and establishment of wind-dispersed epiphytes, like Orchidaceae, Bromeliaceae, Asclepiadaceae, Nepenthalaceae, Ericaceae, and Melastomataceae (see MADISON 1979), or bird-dispersed epiphytes like Gesneriaceae, Rubiaceae, Piperaceae, Moraceae and Clusiaceae. The occurrence of AGs in some habitats may not be erratic, and probably corresponds to specific seedling habitats (LONGINO 1986), such as tree crotches (NADKARNI & MATELSON 1991), since they are composed of an accumulation of humus, and maybe mycorrhizae necessary for the establishment of some plant species such as the Orchidaceae. Some large plants, such as Clusia sp.…”

Seasonality and mycorrhizal colonization in three species of epiphytic orchids in southeast Mexico

“…Results of the analysis of canopy "soils" indicate that they are rich in organic material and nutrients, mainly NO 3 , NH 4 and PO 4 , which are, however, difficult to assimilate due to acidity and the particular nutrient balance of the medium (Lesica & Antibus 1990;Nadkarni & Matelson 1991). In addition, the surface area of the roots of epiphytic orchids is small in proportion to the biomass of the stems and leaves (Benzing & Ott 1981).…”