Investigation of 78 surface pollen samples from warm temperate hilly areas of eastern China shows that pollen assemblages in areas of different land use are significantly different.Pollen concentrations in wastelands are higher than in plantations;these,in turn,are higher than in farmlands;implying that pollen concentration decreases with increasing human impact.Arboreal pollen dominated by Pinus and Quercus is common in all samples.Herbaceous pollen percentages are higher while shrub pollen,fern spores and fern allies are lower in farmlands than in wastelands.Crop pollen is only detectable in and near farmlands;its percentages and concentrations decrease in wastelands.Cereal and Cruciferae pollen percentages average 16.7% and 6.7% in farmland respectively,but Cereal reduces to less than 3% and Cruciferae to less than 0.5% in nearby wastelands.Principle coordinates analysis and clustering analysis indicate that pollen assemblages from farmlands are distinguishable from those under other vegetation types.Occurrence of Poaceae,Chenopodiaceae,Artemisia,and Compositae pollen and Selaginella sinensis spores are closely related to human activities,and their types and frequencies indicate intensity of human impact.The spatial distribution of crops,Chenopodiaceae,and Artemisia reflects changes in both natural environments and human activities.Percentages of cereal and Cruciferae pollen,for example,increase with decreasing altitude,but decrease with increasing latitude.Understanding pollen assemblages under artificial and human-disturbed vegetation in hilly areas may aid understanding of human impacts on the plains during the early-middle Holocene.
DING Wei PANG RuiMing XU QingHai LI YueCong CAO XianYong
花粉产量是定量重建古植被、古气候的必要条件,目前花粉产量包括相对花粉产量和绝对花粉产量。由于较难获得多年连续的花粉沉积数据,学者多倾向于使用相对花粉产量进行古植被定量重建。相对花粉产量是某一花粉类型相对于同一参考种的花粉产量的比值(参考种通常选取植物群落和花粉组合中出现频率较高的同一花粉类型),可通过ERV(Extended R-value)模型进行估算,但其准确性受植被调查方法和模型假设条件影响较大。本文介绍了估算相对花粉产量所需的植被调查方法和利用花粉产量定量重建植被景观的模型。目前较成熟的模型为景观重建模型(Landscape Reconstruction Algorithm),包括REVEALS模型(Regional Estimates of Vegetation Abundance from Large Sites,适用于面积≥1~5km^2的沉积盆地植被重建)和LOVE模型(Local Vegetation Estimates,适用于面积为0.1~1.0km^2的沉积盆地植被重建)。欧洲及我国不同区域相对花粉产量和REVEALS模型定量重建研究结果均表明,重建后的古植被景观能较好反映当地的古植被组成。
Pollen assemblages of 53 surface pollen samples from farmlands and wastelands in Northeast China were analyzed. Tree pollen percentages were usually higher than 30%, with Pinus (26.9%), Quercus (0.9%), Betula (0.9%) and Populus (0.7%) as the major types, and herb pollen percentages were usually higher than 50%, with weedy Poaceae (8.7%), Chenopodiaceae (7.1%), Artemisia (1.9%) and Compositae (3.5%) as the major taxa. Thus, the pollen assemblages were consistent with the regional vegetation compositions. However, there were differences in pollen assemblages among regions, especially among different geomorphological units. For example, in the mountains, there were more types of tree pollen and higher total percentages (average 42%) than in other areas, while cereal pollen percentages were lowest (11.2%). In the hills and high plains, herbs made up more than 60% of the pollens, with cereals (average 53.6%) the dominant type. In the low plains, pollen types were similar to those in the hills and high plains, but total pollen concentrations and the proportion of Concentricystes were much higher, while cereal pollen percentages were slightly lower (average 41.6%). Pollen assemblages in different land use types also differed. For example, in farmland, cereal pollen percentages were more than 40% and Chenopodiaceae was usually less than 2.5%, while in wasteland, weedy Poaceae was usually less than 10% and Chenopodiaceae was usually higher than 25%. Total pollen concentrations in farmland (average 3909 grains/g) were much lower than in wasteland (average 15074 grains/g). Redundancy analysis revealed that pollen assemblages were significantly negatively correlated with mean annual temperature (-0.73) and July mean temperature (-0.81) and significantly positively correlated with mean annual precipitation (0.48), indicating that pollen assemblages in the artificial or human-disturbed vegetation reflect regional climate well. Comparison of pollen assemblages in different areas of northern China showed that pollen concentratio
LI ManYueLI YueCongXU QingHaiPANG RuiMingDING WeiZHANG ShengRuiHE ZhiGuo
