Effects of changes in land management practices on pollen productivity of open vegetation during the last century derived from varved lake sediments
Effects of changes in land management practices on pollen productivity of open vegetation during the last century derived from varved lake sediments
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DOI：
10.1177/0959683614567881
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发表时间：
2015-01
期刊：
影响因子：
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通讯作者：
M. Theuerkauf;N. Dräger;U. Kienel;A. Kuparinen;A. Brauer
中科院分区：
文献类型：
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作者：
M. Theuerkauf;N. Dräger;U. Kienel;A. Kuparinen;A. Brauer
花粉生产力是量化过去植物丰富度和植被开阔程度的关键参数。在这项研究中，我们探索了土地管理的变化如何影响花粉生产力。我们研究了在公元1880年至2010年期间沉积在德国东北部低地的铁夫尔湖大部分年度层状沉积物中的花粉沉积。在此期间，土地利用强度增加，主要是因为自1950年代以来，主要是通过广泛采用人造化肥、除草剂和重型机械。尽管土地利用统计数据显示，总体植被开阔程度基本保持不变，但在研究期间，非树栖花粉沉积(来自草本植物和草本植物)急剧下降。这一下降的部分原因可以解释为转向小麦和油菜等几乎不释放花粉的作物。此外，加强草原管理，包括排水，也有助于降低花粉沉积，因为草原群落中的车前草和鲁梅克斯减少了。然而，最重要的影响是草的花粉生产力下降了约60%，这很可能是对更早和更频繁的割草的反应，尽管草种组成的变化也可能起到了一定作用。我们的结果表明，土地利用的类型和强度对牧草的花粉生产力有很大的影响(对后续作物的影响较小)。由于草的花粉沉积是植被开放的主要指标，而草是大多数PPE研究中常见的参考类群，因此草的花粉生产力的变化在重建过去的植被覆盖时引入了迄今被忽视的误差。我们的研究初步估计了这种影响的程度。
Pollen productivity is a key parameter to quantify past plant abundances and vegetation openness. In this study we explore how changes in land management influence pollen productivity. We study pollen deposition in largely annually laminated sediments from Lake Tiefer See in the Northeastern German lowlands deposited between AD 1880 and 2010. During this period, land use intensity has increased predominantly through the widespread introduction of artificial fertilizers, herbicides and heavy machinery mainly since the 1950s. Although land use statistics show that overall vegetation openness remained largely constant, non-arboreal pollen deposition (from herbs and grasses) sharply declined over the study period. This decline can be partly explained by a shift towards crops that emit little pollen such as wheat and oilseed rape. Furthermore, intensified grassland management, including drainage, also contributed to lower pollen deposition because of the decline of Plantago lanceolata and Rumex from grassland communities. However, the most important effect is a decline in pollen productivity of grasses of about 60%, which most likely is a response to earlier and more frequent mowing, although changes in grass species composition may also have played a role. Our results show that the type and intensity of land use have a strong effect on pollen productivity of grasses (and smaller effects on further crops). Since grass pollen deposition is a main proxy for vegetation openness and grasses are the common reference taxon in most PPE studies, variations in the pollen productivity of grasses introduce so far neglected errors in the reconstruction of the past vegetation cover. Our study provides a first estimate about the magnitude of this effect.