Pollen percentage thresholds of Abies alba based on 13-year annual records of pollen deposition in modified Tauber traps: perspectives of application to fossil situations

摘要

Abies alba (fir), a submontane tree from Central European mountains and uplands, is of special interest for\udpalaeoecological and palaeoclimate interpretations due to its sensitivity to air and soil humidity. Its present\uddistribution limit in the uplands of SE Poland is still a matter of debate. In the Holocene fir expanded to\udPoland very late, but early fir populations are supposed to occur in the Šumava Mts (Czech Republic). The\udstudy aims: to estimate pollen thresholds for fir presence/absence in Bohemia (Czech Republic) and Poland\udon the basis of modified Tauber pollen traps; to use these thresholds for tracing fir presence in two pollen\uddiagrams from Poland (Słone and Bezedna lakes) in the border zone between the Roztocze region (with fir\udforest stands today) and Polesie (where fir has never played an important role); and to investigate how\udthe percentage presence/absence threshold can be used to trace the occurrence and abundance of fir trees\udin the Šumava Mts based on the pollen diagrams of Rokytecká slat' and Mrtvý luh.\udThe fir pollen thresholds estimated in terms of PAR (pollen accumulation rates or pollen influx) range from\ud843 (grains cm−2 year−1) (Roztocze) to 61 (Krkonoše) and 49 (Šumava). Percentage thresholds range\udfrom 0.3% in Krkonoše where fir trees are not present within 4 km to 22% in fir-dominated woodland of\udthe Roztocze, providing evidence of strong underrepresentation of fir in the pollen deposition. Application\udof these percentage thresholds to the Słone and Bezedna pollen diagrams indicates that occurrence of fir in\udthe region is possible from 3.5 cal ky BP onwards, though the evidence is not decisive. In the Šumava, a\udlow representation of fir pollen (1–2%) reflecting presence of scattered fir trees was detected as early as ca.\ud7.0 cal ky BP.