Does livestock grazing affect sediment deposition and accretion rates in salt marshes
Does livestock grazing affect sediment deposition and accretion rates in salt marshes
复制标题
牲畜放牧是否会影响盐沼中的沉积物沉积和增生率
DOI：
10.1016/j.ecss.2013.10.026
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发表时间：
2013
影响因子：
2.8
通讯作者：
K. Jensen
中科院分区：
文献类型：
--
作者：
S. Nolte;F. Müller;M. Schuerch;A. Wanner;P. Esselink;J. Bakker;K. Jensen
以毫米/年为单位的盐沼垂直生长速率，可能受到放牧牲畜两种方式的影响：通过踩踏增加土壤压实的直接影响，以及通过减少地上生物量从而减少沉积物沉积速率（以克/平方米/年为单位）的间接影响。虽然增加率和由此产生的表面海拔变化在很大程度上决定了盐沼海平面上升（SLR）的弹性，牲畜放牧对增加率的影响研究甚少。因此，本研究的目的是调查牲畜放牧对盐沼增长率的影响。我们假设，与未放牧的盐沼相比，放牧的盐沼的吸积会更低。在四个研究站点沿着大陆海岸的瓦登海（在东南北海），吸积率，沉积物沉积率，和土壤压实放牧和未放牧沼泽地进行了分析，使用137 Cs放射性核素测年法。近几十年来的平均吸积速率为11.6毫米/年，因此高于目前和预计的SLR速率。无论是加积，也没有沉积物沉积速率放牧处理之间的显着差异。同时，土壤紧实度明显受到放牧的影响，放牧区土壤干容重显著高于未放牧区。基于这些结果，我们得出结论，其他因素的影响是否放牧有影响的加积和沉积物沉积速率和放牧对沼泽生长的影响不遵循一个直接的因果链。它可能有很大的重要性时，与其他生物和非生物过程的沼泽。
Accretion rates, defined as the vertical growth of salt marshes measured in mm per year, may be influenced by grazing livestock in two ways: directly, by increasing soil compaction through trampling, and indirectly, by reducing aboveground biomass and thus decreasing sediment deposition rates measured in g/m² per year. Although accretion rates and the resulting surface elevation change largely determine the resilience of salt marshes to sea-level rise (SLR), the effect of livestock grazing on accretion rates has been little studied. Therefore, this study aimed to investigate the effect of livestock grazing on salt-marsh accretion rates. We hypothesise that accretion will be lower in grazed compared to ungrazed salt marshes. In four study sites along the mainland coast of the Wadden Sea (in the south-eastern North Sea), accretion rates, sediment deposition rates, and soil compaction of grazed and ungrazed marshes were analysed using the137Cs radionuclide dating method. Accretion rates were on average 11.6 mm yr−1during recent decades and thus higher than current and projected rates of SLR. Neither accretion nor sediment deposition rates were significantly different between grazing treatments. Meanwhile, soil compaction was clearly affected by grazing with significantly higher dry bulk density on grazed compared to ungrazed parts. Based on these results, we conclude that other factors influence whether grazing has an effect on accretion and sediment deposition rates and that the effect of grazing on marsh growth does not follow a direct causal chain. It may have a great importance when interacting with other biotic and abiotic processes on the marsh.