Lightning-Caused and Human-Induced Forest Fires as Evidenced By Pteridium Spores in Selected Quaternary Records from Poland

Abstract

Ab stractThe oc cur rence of Pteridium spores -the com mon fire-adapted plant -was ob served in Po land's Pleis to cene (three interglacials and nu mer ous interstadials) and Ho lo cene pol len se quences. Un til the on set of the mid dle Ho lo cene, bracken was re corded rel a tively rarely. This marks cli ma tic con di tions with spo radic wildfires, fol lowed by quick removal of the clones (or main te nance of the clones in a sup pressed state) in the sub se quent, post fire successional stages. In each inter gla cial we can also iden tify short pe ri ods (most of ten syn chro nous) of some what higher fre quency of Pteridium, in di cat ing a pos si ble in crease in nat u ral fires as an ef fect of stormy con di tions. These short pe ri ods are placed mainly within phases dom i nated by co nif er ous wood lands. The very high con tent of bracken found from a reanalysis of the long Saalian se quence at Ossówka as three reg u lar cul mi na tions just above three non-tree phases, east ern Po land is the unique ex cep tion. To ex plain this we found the close mod ern an a logue of the above phe nom e non in the Alas kan re gion, at the bound ary be tween the tun dra and the bo real zone where in a very nar row for est zone, espe cially with the con ti nen tal sig na ture, light ning-ini ti ated fires are very fre quent (the edge ef fect). Pleis to cene re cords of bracken dur ing for est pe ri ods might in di cate that thun der storms and light ning strikes were re spon si ble for its higher con tent. This is not to ex clude the pos si bil ity that inter gla cial fires were set by Palaeo lithic hu mans. How ever, it is more likely that the wildfires were uti lized and to some ex tent con trolled, es pe cially at Ossówka, where the palaeolake ex isted for a long time af ter the inter gla cial; and this surely at tracted the at ten tion of game and hu mans. Our in ves ti gations show that rare, more abun dant Pteridium in the Pleis to cene se quences can be traced through out the cor re sponding pe ri ods even at dis tant sites. This might be in di rect ev i dence of a cli ma tic pat tern that pro mote stormy con di tions and fires at that time. In the Ho lo cene, dif fer ent fac tors seem to be re spon si ble for the long-term dy nam ics in Pteridium clones. Both in Po land and in ad ja cent ar eas bracken peaked in the mid dle Ho lo cene from 8000 to 5000 BP, when this ter ri tory was oc cu pied by de cid u ous wood lands. There is agree ment that this is due to burn ing of for ests by the hunter-gath erer so ci et ies of the Late Mesolithic. How ever, in spite of in creased clear ings in the sub se quent phases bracken sub stan tially de creased in abun dance. This means first of all that fires rather than clear ings were re spon si ble for the rise in Pteridium spores in the Ho lo cene pol len se quences.Key words: bracken spores, fires, Qua ter nary, Po land IN TRO DUC TIONPteridium aquilinum is a com mon plant grow ing on every con ti nent ex cept in Arc tic/Ant arc tic re gions. For many rea sons -first of a...

Terrestrial versus marine archives: biostratigraphical correlation of the Middle Pleistocene lacustrine records from central Europe and their equivalents in the deep-sea cores from the Portuguese margin

“…Each interstadial starts with a quick suc ces sion of ju ni per fol lowed in the first two interstadials by birch for est with larch. Such for est rep re sents partly post-fire veg e ta tion as in di cated by abun dant Pteridium spores (Biñka and Nitychoruk, 2013). Scots pine for est is a climax com mu nity.…”

“…Typ i cal suc ces sion of main plant com po nents, the pres ence of two intra-inter gla cial cli mate os cil la tions: OHO and YHO, in dic a tive exotics, e.g. Pterocarya, and cul mi na tion of yew in the first half of the se quence prove its Holsteinian age (Biñka and Nitychoruk, 2013). We can find the same fea tures in the suc ces sions in the Cen tral Mas sif, Germany and Great Brit ain (Turner, 1970;Ur ban et al, 1991;Reille et al, 2000).…”

“…The Ossówka sec tion re veals a con tin u ous se quence of carbon ate gyttja, lam i nated in the inter gla cial part and with out any strati graphi cal gaps (Krupiñski, 1995;Nitychoruk, 2000). Quite re cently, a new, 55 m long core from the cen tral part of the palaeolake was ana lysed (Biñka and Nitychoruk, 2013). The site at £uków, sit u ated not far from Ossówka, is rep re sented by a 10 m long se quence of lac us trine de pos its.…”

“…1), last ing ~70 ky (Krupiñski, 1995;Nitychoruk et al, 2005;Biñka and Nitychoruk, 2013), 70 Krzysztof Biñka and Leszek Marks gives a new im pulse in this area of re search. The se quence started in the Late Elsterian, con tin ued through out the Holsteinian, and ter mi nated in the Saalian (Ta ble 1).…”

Holocene history of landscape development in the catchment of Lake Skogstjern, southeastern Norway, based on a high-resolution multi-proxy record

“…This palynological record may indicate natural disturbances, such as open areas along the lakeshore, precipices or rock outcrops with thin soil cover, talus formations and landslides where sufficient light is present, enabling these plants to grow. However, the abundance of pollen of those representatives of disturbed vegetation appear together with elevated levels of microscopic charcoal particles (up to 2.6 × 10 3 particles/cm 3 ) and Pteridium , a common fire-adapted fern (Bińka and Nitychoruk, 2013; Tinner et al, 2000). The increase in charcoal dust could be a result of natural burning, but the pollen stratigraphical evidence shows a deciduous tree cover with birch and hazel stands dominating.…”