State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, 210008 Nanjing, PR China; College of Resources and Environment Sciences, Hebei Normal University, 050024 Shijiazhuang, PR China; Hebei Key Laboratory of Environmental Change and Ecological Construction, Hebei Normal University, 050024 Shijiazhuang, PR China; University of Chinese Academy of Sciences, 100049 Beijing, PR China.
College of Resources and Environment Sciences, Hebei Normal University, 050024 Shijiazhuang, PR China; Hebei Key Laboratory of Environmental Change and Ecological Construction, Hebei Normal University, 050024 Shijiazhuang, PR China.
Sci Total Environ. 2017 May 15;586:25-41. doi: 10.1016/j.scitotenv.2017.02.027. Epub 2017 Feb 14.
Vegetation reconstructions from palaeoecological records depend on adequate understanding of relationships between modern pollen, vegetation and climate. A key parameter for quantitative vegetation reconstructions is the Relative Pollen Productivity (RPP). Differences in both environmental and methodological factors are known to alter the RPP estimated significantly, making it difficult to determine whether the underlying pollen productivity does actually vary, and if so, why. In this paper, we present the results of a replication study for the Bashang steppe region, a typical steppe area in northern China, carried out in 2013 and 2014. In each year, 30 surface samples were collected for pollen analysis, with accompanying vegetation survey using the "Crackles Bequest Project" methodology. Sampling designs differed slightly between the two years: in 2013, sites were located completely randomly, whilst in 2014 sampling locations were constrained to be within a few km of roads. There is a strong inter-annual variability in both the pollen and the vegetation spectra therefore in RPPs, and annual precipitation may be a key influence on these variations. The pollen assemblages in both years are dominated by herbaceous taxa such as Artemisia, Amaranthaceae, Poaceae, Asteraceae, Cyperaceae, Fabaceae and Allium. Artemisia and Amaranthaceae pollen are significantly over-represented for their vegetation abundance. Poaceae, Cyperaceae and Fabaceae seem to have under-represented pollen for vegetation with correspondingly lower RPPs. Asteraceae seems to be well-represented, with moderate RPPs and less annual variation. Estimated Relevant Source Area of Pollen (RSAP) ranges from 2000 to 3000m. Different sampling designs have an effect both on RSAP and RPPs and random sample selection may be the best strategy for obtaining robust estimates. Our results have implications for further pollen-vegetation relationship and quantitative vegetation reconstruction research in typical steppe areas and in other open habitats with strong inter-annual variation.
植被重建依赖于对现代花粉、植被和气候之间关系的充分理解。定量植被重建的一个关键参数是相对花粉生产力 (RPP)。已知环境和方法因素的差异会显著改变估计的 RPP，这使得难以确定花粉生产力是否确实存在差异，如果存在差异，原因是什么。在本文中，我们报告了 2013 年和 2014 年在典型的中国北方草原区——坝上草原进行的复制研究的结果。在每年，采集了 30 个表面样本进行花粉分析，并使用“Crackles Bequest Project”方法进行伴随的植被调查。这两年的采样设计略有不同：2013 年，采样点完全随机分布，而 2014 年，采样点限制在距道路几公里以内。因此，RPP 中的花粉和植被谱都存在强烈的年际变化，年降水量可能是这些变化的关键影响因素。这两年的花粉组合都以草本类群为主，如蒿属、苋科、禾本科、菊科、莎草科、豆科和葱属。蒿属和苋科花粉相对于其植被丰度明显过量。禾本科、莎草科和豆科的花粉似乎对植被的代表性不足，相应的 RPP 也较低。菊科似乎代表良好，具有中等的 RPP 和较少的年际变化。估计的相关源区花粉（RSAP）范围从 2000 到 3000 米。不同的采样设计对 RSAP 和 RPP 都有影响，随机样本选择可能是获得稳健估计的最佳策略。我们的结果对典型草原区和其他具有强烈年际变化的开阔生境中的进一步花粉-植被关系和定量植被重建研究具有重要意义。
