SEEDLING GROWTH PERFORMANCE OF SYZYGIUM SPECIES IN SIMULATED LIGHT AND SOIL NUTRIENT ENVIRONMENTS IN A LOWLAND RAIN FOREST IN SRI LANKA

ABSTRACTNitrogenase activity in the surface soil and litter layers from a tropical lowland rain forest and an adjacent fernland in Sri Lanka was measured by the acetylene reduction method. The total amount of acetylene reduced, a measure of biological nitrogen fixation, was greater in the fernland (38.4 µmol m−2 h−1) than in the forest (15.3–29.2 µmol m−2 h−1). In both ecosystems the nitrogenase activity was greater (59–85%) in the soil than in the litter layer. The rates of acetylene reduction in soil and litter showed an inverse relationship with the decay constants of mixed litter and a positive relationship was found between the rate of acetylene reduction and the C:extractable nitrogen ratio of the soil. The relatively greater rate of nitro genase activity coupled with the slower rate of litter decomposition in the fernland indicates that accumulation of nitrogen may result in the soil and litter layers of the deforested areas during their aggrading phases.

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Community assembly during recovery of tropical lowland rain forest from abandoned shift-ing cultivation lands on Hainan Island, China

Chinese Journal of Plant Ecology ◽

10.3724/sp.j.1258.2013.00043 ◽

2013 ◽

Vol 37 (5) ◽

pp. 415-426

Author(s):

Yun-Feng HUANG ◽

Xing-Hui LU ◽

Run-Guo ZANG ◽

Yi DING ◽

Wen-Xing LONG ◽

...

Keyword(s):

Community Assembly ◽

Rain Forest ◽

Hainan Island ◽

Lowland Rain Forest ◽

Tropical Lowland ◽

Tropical Lowland Rain Forest

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Ants accelerate litter decomposition in a Costa Rican lowland tropical rain forest

Journal of Tropical Ecology ◽

10.1017/s0266467412000375 ◽

2012 ◽

Vol 28 (5) ◽

pp. 437-443 ◽

Cited By ~ 15

Author(s):

Terrence P. McGlynn ◽

Evan K. Poirson

Keyword(s):

Mass Loss ◽

Leaf Litter ◽

Litter Decomposition ◽

Rain Forest ◽

Costa Rican ◽

Tropical Rain Forests ◽

Rain Forests ◽

Food Web Structure ◽

Litter Bags ◽

Lowland Rain Forest

Abstract:The decomposition of leaf litter is governed, in part, by litter invertebrates. In tropical rain forests, ants are dominant predators in the leaf litter and may alter litter decomposition through the action of a top-down control of food web structure. The role of ants in litter decomposition was investigated in a Costa Rican lowland rain forest with two experiments. In a mesocosm experiment, we manipulated ant presence in 50 ambient leaf-litter mesocosms. In a litterbag gradient experiment, Cecropia obtusifolia litter was used to measure decomposition rate constants across gradients in nutrients, ant density and richness, with 27 separate litterbag treatments for total arthropod exclusion or partial arthropod exclusion. After 2 mo, mass loss in mesocosms containing ants was 30.9%, significantly greater than the 23.5% mass loss in mesocosms without ants. In the litter bags with all arthropods excluded, decomposition was best accounted by the carbon: phosphorus content of soil (r2 = 0.41). In litter bags permitting smaller arthropods but excluding ants, decomposition was best explained by the local biomass of ants in the vicinity of the litter bags (r2 = 0.50). Once the microarthropod prey of ants are permitted to enter litterbags, the biomass of ants near the litterbags overtakes soil chemistry as the regulator of decomposition. In concert, these results support a working hypothesis that litter-dwelling ants are responsible for accelerating litter decomposition in lowland tropical rain forests.

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