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曹丹丹, 王东, 杨雪, 郭璇, 牛红玉. 泥沙埋深对苦草和微齿眼子菜及两物种混合分解的影响[J]. 水生生物学报, 2016, 40(2): 327-336. DOI: 10.7541/2016.44
引用本文: 曹丹丹, 王东, 杨雪, 郭璇, 牛红玉. 泥沙埋深对苦草和微齿眼子菜及两物种混合分解的影响[J]. 水生生物学报, 2016, 40(2): 327-336. DOI: 10.7541/2016.44
CAO Dan-Dan, WANG Dong, YANG Xue, GUO Xuan, NIU Hong-Yu. DECOMPOSITION OF TWO SUBMERGED MACROPHYTES AND THEIR MIXTURE: EFFECT OF SEDIMENT BURIAL[J]. ACTA HYDROBIOLOGICA SINICA, 2016, 40(2): 327-336. DOI: 10.7541/2016.44
Citation: CAO Dan-Dan, WANG Dong, YANG Xue, GUO Xuan, NIU Hong-Yu. DECOMPOSITION OF TWO SUBMERGED MACROPHYTES AND THEIR MIXTURE: EFFECT OF SEDIMENT BURIAL[J]. ACTA HYDROBIOLOGICA SINICA, 2016, 40(2): 327-336. DOI: 10.7541/2016.44

泥沙埋深对苦草和微齿眼子菜及两物种混合分解的影响

DECOMPOSITION OF TWO SUBMERGED MACROPHYTES AND THEIR MIXTURE: EFFECT OF SEDIMENT BURIAL

  • 摘要: 为探讨泥沙淤积对水生植物分解的影响,研究了沉水植物苦草(Vallisneria natans)、微齿眼子菜(Pota-mogeton maackianus)及两物种混合在底泥中不同埋深(0 和5 cm)的分解速率和养分动态,实验周期为117d。结果显示:(1)在0和5 cm埋深处理下,苦草、微齿眼子菜及两物种混合的分解速率均表现为苦草最快,微齿眼子菜最慢,物种混合介于两单种之间。与0 cm处理相比,在5 cm埋深处理下苦草、微齿眼子菜及两物种混合的分解速率显著降低(P0.05)。苦草在0和5 cm埋深处理下分解35天后干重剩余率分别为0和43.51%、在5 cm处理下分解82d后干重剩余率为0。微齿眼子菜和两物种混合在5 cm埋深处理下分解117d后的干重剩余率分别提高了31.09%和37.44%。(2)与0 cm处理相比,5 cm埋深处理显著抑制苦草、微齿眼子菜及两物种混合的N、P释放。苦草在0和 5 cm埋深处理下分解35天后N剩余率分别为0和31.28%、P剩余率分别为0和24.45%。在5 cm埋深处理下分解117天后微齿眼子菜N和P剩余率分别提高了19.45%和14.73%、两物种混合N、P剩余率分别提高了41.57%和22.82%。(3)两物种混合在0和5 cm埋深处理下,其分解速率均表现为加和效应,但N、P元素释放在0 cm处理下分别表现为协同效应和加和效应,在5 cm埋深处理下均表现为拮抗效应。(4)随着分解的进行,5 cm埋深处理下的苦草和微齿眼子菜的微生物呼吸速率均显著降低,物种混合的微生物生物量始终低于0 cm处理。这些结果表明泥沙埋深显著降低了苦草、微齿眼子菜及两物种混合的分解速率和N、P元素释放,物种混合的N、P元素释放在分解后期均因沉积作用而产生了拮抗效应。此外,泥沙埋深对分解的抑制作用与微生物呼吸及生物量降低有密切的关系。研究结果可为认识水生植物分解对沉积作用的响应机制提供资料,并为了解水生植物分解对底质营养动态的影响提供参考。

     

    Abstract: Decomposition of aquatic macrophytes makes the nutrients stocked in biomass release to the surroundings, and thereby can considerably affect nutrient cycling and energy flow in aquatic ecosystem. In most case, aquatic macrophytes may readily produce a considerable amount of stem and/or leaf fragments due to both natural and anthropogenic disturbances. The detached fragments will be deposited within the sediment. To date, the breakdown of aquatic macrophytes associated with sedimentation remains largely unexplored. Vallisneria natans and Potamogeton maackianus are two dominant submerged plants in shallow lakes of the Yangtze River basin of China. In the field, a substantial amount of the detached plant parts may be produced and deposited separately or coupled with each other at the substrate surface or buried within the sediment, contributing to the formation of an organic slime in the lakeshore areas. To investi-gate the effect of sediment burial on the decomposition of V. natans, P. maackianus and their mixture, three types of plant materials confined in litterbags were incubated and subjected to 0 cm and 5 cm buried treatments for 117 days. There were 5 g materials used for each species and mixture (2.5:2.5 of V. natans: P. maackianus, w/w basis) in the litterbags. The decomposition rates, nitrogen and phosphorus content of the remaining materials, and microbial respiration and biomass were measured at days 7, 19, 35, 56, 82 and 117 respectively. Decomposition rates of both V. natans and P. maackianus were significantly and positively correlated with initial N contents (P0.05, r=0.896), and nega-tively correlated with C/N ratio (P0.05, r=-0.963). The decomposition rate was the highest for V. natans, the lo-west for P. maackianus, and intermediate for their mixture. The decomposition rate and nutrient release of V. natans, P. maackianus and their mixture were greatly reduced in 5 cm burial treatments compared to 0 cm treatments. After 35 days experiment, the dry mass remaining percentage of V. natans was 0 and 43.51% under 0 cm and 5 cm burial treatments, respectively. After 82 days experiment, the dry mass remaining percentage of V. natans was close to 0 in 5 cm burial treatments. Dry mass remaining of P. maackianus and V. natansP. maackianus was significantly higher in 5 cm burial treatments compared to 0 cm treatments, with an increase of 31.09% and 37.44%, respectively. The nutrient release of V. natans, P. maackianus and their mixture were significantly inhibited when they were buried at 5 cm depth. After 117 days experiment, the N and P remaining percentage of P. maackianus was significantly higher in 5 cm burial treatments compared to 0 treatments, with an increase of 19.45% and 14.73%, respectively. For the mixture, the N and P remaining percentage was higher in 5 cm burial treatments than 0 treatments, with an increase of 41.57% and 22.82%, respectively. After 35 days experiment, the N remaining percentage of V. natans was close to 0 and 31.28%, and P remaining percentage was close to 0 and 24.45% under 0 and 5 cm burial treatments, respectively. For the mixture, the observed mass remaining did not significantly differ from the expected under two treatments, indicating that an addi-tive effect existed for the decomposition rate and the mixing effect was irrelevant to the incubated locations (i.e., at the surface or buried within the sediment). In addition, additive effect of N and P release of the mixed material also occurred at the early stage of decomposition. In the subsequent time, the observed N remaining of the mixed material were lower than the expected (P0.05) while the observed P remaining did not differ from the expected (P0.05) in 0 cm burial treatment, indicating a synergistic effect on N release and an additive effect on P release occurred. In contrast, the observed N and P remaining were higher than the expected in 5 cm burial treatment, indicating antagonistic effects on N and P release occurred. The microbial respiration rate of both V. natans and P. maackianus and the microbial biomass of the mixed material were much lower in 5 cm burial treatments compared to 0 treatments. This implied that limitation of microbial activities to plant materials induced from the sediment burial would greatly reduce the rate of decomposition and nutrient release of aquatic macrophytes. We concluded that sediment burial may lead to a decrease of decomposition rates and nutrient release of both single submerged plants and their mixture, which is closely linked to substantial decline of microbial activities by sedimentation. We further suggested that the observed N and/or P-stimulated increases of the mixed plant material in response to sedimentation would contribute to the changes in nutrient availability in the lakeshore area.

     

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