PROJECT DESCRIPTION : Rates of decomposition depend on the particular interactions between producers and decomposer food webs. This interactions are determined by the intrinsic characteristics of both plant and decomposers and are as well influenced by abiotic factors. Field studies were designed to determine the influences of environmental parameters such as climate and microsite variation on the decomposition rates of five tree species from The Luquillo Experimental Forest (LEF). This also allowed us to determine the influence of leaf quality on the decomposer community and whether leaf physical, structural or phylogenetic relationships could be used as predictors of decomposition rates. Microcosms were used to separated the contribution of interactions between dominant plants and fungal species in decomposition rates. The rates of decomposition were determined by mass loss in both the field and microcosms experiments. In the microcosms systems, CO2 evolution by the decomposition of each of the five leaf litter substrates, by fungal species isolated from that particular leaf or from any of the other litter types, was obtained by using sodium hydroxide traps. There were significant differences in decomposition rates among leaf litter types both in field and microcosms experiments. There was also a significant effect of dry and wet periods in decomposition rates. Leaf litter decomposed faster under their tree sources than in a common plot. Among the leaf quality parameters, the lignin and nitrogen to lignin ratios were the best predictors of decomposition rates. Non polar elements, water soluble (simple sugars), P and Ca were positively correlated with percent mass loss (PML) while C was negatively correlated with PML. In the microcosms experiments we did not found specificity between fungi and their substrate (where the fungus was isolated), neither to substrates that were chemically, physically or structurally related to the plant were the fungi was originally isolated. Nevertheless, there were differential responses of particular fungi to plant substrates as well as influences of plant species on the fungal decomposers performance. The differential contributions of leaf species to carbon budgets (mass remaining and CO2 release) may be important in determining management practices for forest and agricultural systems. We found that species such as Manilkara bidentata may retain carbon in the ecosystem while other species such as Sapium laurocerasus decomposed rapidly and therefore, released nutrients quickly but with greater carbon losses. The absence of tight links between plants and fungal decomposer may indicate adaptation of fungi to changes in resource availability in a disturbed forest. Alternatively, this might indicate that the presence of a fungi in a particular substrate does not depend on the substrate's chemical o physical composition but on the presence of other members of the detrivoral community. Although the presence of generalist basidiomycetes made an important contribution to the decomposition of leaf species, the diversity of the decomposer and detrivoral community might be important in maintaining nutrient balances in the ecosystems since random encounters of plants, decomposers and detrivores may determine the residence time of a substrate on the forest floor.
| Record_num | Catalog_na | Identifier |
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125
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LTERDBAS | Interactions between plants and fungi and their roles in decay rates and CO2 release in five tropical leaf species (Metadata only) |
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124
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LTERDBAS | Factors
influencing decomposition of leaves for five plant species at El Verde (Metadata
only) |
Created By: Eda C. Melendez-Colom (emelend@lternet.edu)
Last Modified On: April 30, 2005