Litter pool sizes,decomposition, and nitrogen dynamics in <Emphasis Type="Italic">Spartina alterniflora</Emphasis>-invaded and native coastal marshlands of the Yangtze Estuary |
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Authors: | Cheng Zhang Liao Yi Qi Luo Chang Ming Fang Jia Kuan Chen Bo Li |
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Institution: | (1) Coastal Ecosystems Research Station of the Yangtze River Estuary, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, The Institute of Biodiversity Science, Fudan University, 200433 Shanghai, China;(2) Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA |
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Abstract: | Past studies have focused primarily on the effects of invasive plants on litter decomposition at soil surfaces. In natural
ecosystems, however, considerable amounts of litter may be at aerial and belowground positions. This study was designed to
examine the effects of Spartina
alterniflora invasion on the pool sizes and decomposition of aerial, surficial, and belowground litter in coastal marshlands, the Yangtze
Estuary, which were originally occupied by two native species, Scirpus mariqueter and Phragmites australis. We collected aerial and surficial litter of the three species once a month and belowground litter once every 2 months. We
used the litterbag method to quantify litter decomposition at the aerial, surficial and belowground positions for the three
species. Yearly averaged litter mass in the Spartina stands was 1.99 kg m−2; this was 250 and 22.8% higher than that in the Scirpus (0.57 kg m−2) and Phragmites (1.62 kg m−2) stands, respectively. The litter in the Spartina stands was primarily distributed in the air (45%) and belowground (48%), while Scirpus and Phragmites litter was mainly allocated to belowground positions (85 and 59%, respectively). The averaged decomposition rates of aerial,
surficial, and belowground litter were 0.82, 1.83, and 1.27 year−1 for Spartina, respectively; these were 52, 62 and 69% of those for Scirpus litter at corresponding positions and 158, 144 and 78% of those for Phragmites litter, respectively. The differences in decomposition rates between Spartina and the two native species were largely due to differences in litter quality among the three species, particularly for the
belowground litter. The absolute amount of nitrogen increased during the decomposition of Spartina stem, sheath and root litter, while the amount of nitrogen in Scirpus and Phragmites litter declined during decomposition for all tissue types. Our results suggest that Spartina invasion altered the carbon and nitrogen cycling in the coastal marshlands of China. |
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Keywords: | Aerial decomposition of litter Coastal marsh Litter allocation Litter nitrogen dynamics Plant invasion Spartina alterniflora Yangtze Estuary |
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