Reconstruction of past landscape openness using the Landscape Reconstruction Algorithm (LRA) applied on three local pollen sites in a southern Swedish biodiversity hotspot
Reconstruction of past landscape openness using the Landscape Reconstruction Algorithm (LRA) applied on three local pollen sites in a southern Swedish biodiversity hotspot
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DOI：
10.1007/s00334-014-0469-8
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发表时间：
2015-03-01
影响因子：
2.5
通讯作者：
Lindbladh, Matts
中科院分区：
文献类型：
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作者：
Hultberg, Tove;Gaillard, Marie-Jose;Lindbladh, Matts
瑞典东南部的Hornso-Allgunnen地区被认为是昆虫生物多样性的热点地区已有大约世纪的历史，被认为是北方物种最丰富的昆虫区系所在地。关于这种生物多样性背后的原因，已经提出了几种假设，但从未在该地区的一小部分地区进行过测试。我们在这里分析该地区的植被覆盖历史，特别是植被开放的可能作用。我们使用花粉数据从三个网站在Hornso-Allgunnen地区，并应用最近开发的景观重建算法（LRA）定量重建过去的植被丰度在当地的空间尺度。该研究表明，至少在过去3,000年里，该地区主要是多样化的，相对开放的森林。一些树木类群，如松，桦和栎，都被认为是重要的，目前的多样性，有一个长期的连续性，在当地的空间尺度，直到最近才常见。小比例的人为花粉指标被发现，这表明小规模的农业，但并没有显着影响该地区的整体树种组成。我们认为，火灾是该地区的森林景观在全新世开放的主要原因，间接地，背后的高昆虫多样性的一个重要因素。然而，昆虫的丰富性很可能也是由于栎属的长期连续性和温暖干燥的当地气候。LRA提供了一个更现实的估计分类群组成相比，花粉百分比单独，无论是乔木和非乔木分类群。花粉百分比和LRA估计的植物丰度之间的差异可能是重要的考虑高现代多样性背后的原因解释从化石花粉记录。我们的研究结果证明了使用LRA沿着传统的花粉百分比的好处。
The Hornso-Allgunnen area in south-eastern Sweden has been known as a biodiversity hotspot for insects for about a century and is considered to host the most species-rich insect fauna in northern Europe. Several hypotheses for the causes behind this biodiversity have been put forward, but never tested for more than small parts of the area. We analyse here the possible role of the area's vegetation-cover history, in particular vegetation openness. We use pollen data from three sites in the Hornso-Allgunnen area and apply the recently developed Landscape Reconstruction Algorithm (LRA) for quantitative reconstruction of past vegetation abundance at the local spatial scale. The study suggests that the area was dominated by diverse, relatively open forest during at least the last 3,000 years. Several tree taxa, such as Pinus, Betula and Quercus that were all suggested to be important for the present diversity, have a long continuity at the local spatial scale and were common until recently. Small proportions of anthropogenic pollen indicators were found, suggesting small-scale agriculture, which however did not considerably affect the area's overall tree species composition. We propose that fire was the main cause for the open character of the area's wooded landscape during the Holocene and, indirectly, an important agent behind the high insect diversity. However, the richness of insects was (and is) most likely also favoured by the long continuity of Quercus, and by the warm and dry local climate. The LRA provides a more realistic estimate of the taxa composition as compared to pollen percentages alone, both for arboreal and non-arboreal taxa. The differences between pollen percentages and LRA-estimates of plant abundance can be important to consider when causes behind high modern diversity are interpreted from fossil pollen records. Our results demonstrate the benefits of using the LRA along with traditional pollen percentages.