Decomposition of tree leaf litter and crop residues from ginkgo agroforestry systems in Eastern China: an in situ study
2018
PURPOSE: Litter decomposition is a crucial biogeochemical process linking nutrient cycling and carbon (C) storage in ecosystems, but few studies have investigated this process in agroforestry systems, where tree leaf litter is mixed with intercrop residues. MATERIALS AND METHODS: A 360-day in situ litter bag decomposition experiment was conducted in three ginkgo (Ginkgo biloba L.) plantation systems (a ginkgo-corn (Zea mays L.)-wheat (Triticum aestivum L.) system, ginkgo-rape (Brassica napus L.)-soybean (Glycine max (L.) Merr.) system, and pure ginkgo system). RESULTS AND DISCUSSION: Ginkgo leaves decomposed fastest in the ginkgo-corn-wheat system, followed by the ginkgo-soybean-rape system, and the pure ginkgo system. Among all litter species, corn leaves and a ginkgo-corn mixture in the ginkgo-corn-wheat system decomposed fastest and wheat straw most slowly. The Olson’s litter exponential decay model showed the same results; approximately 9 months and slightly less than 27 months was required to decompose 50 and 95% of the litter, respectively. Compared to single-species litter, mixed litters accelerated litter decomposition, except for the ginkgo-wheat mixture. Litter nitrogen (N) loss varied dramatically among litter species during the 360-day in situ incubation. CONCLUSIONS: The agroforestry system, litter quality, and mixed effects play important roles in litter decomposition. The Ca content, organic carbon, and living vegetation should be taken into account when studying litter decomposition in agroforestry. Analysis during the litter decomposition process clearly indicated that litter N loss changes dramatically.
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