Testing the influence of climate, human impact and fire on the Holocene population expansion of Fagus sylvatica in the southern Prealps (Italy)

Abstract

This study addresses the timing and causes of the Holocene population expansion of Fagus sylvatica at two sites in the southern Prealps (Italy): Lago di Fimon and Lago Piccolo di Avigliana. At both sites pollen and microcharcoal have been analysed at high temporal resolution. The impact of humans and of fire on the forest dynamics is tested by means of time-series analysis and the influence of climatic change has been inferred from summer temperature and precipitation reconstructions in the Alps. The time intervals during which the population expansion of F. sylvatica occurred (ie, phases during which population doubling times were shortest) is determined by fitting linear regressions through the ln-transformed Fagus pollen-accumulation rate (ln(PAR)). At Lago di Fimon, the population expansion of F. sylvatica occurred at 7300–6400 cal. yr BP (FIM I). After a marked decline the population re-expanded at 5500–4700 cal. yr BP (FIM II). At Lago Piccolo di Avigliana F. sylvatica expanded c. 5300–4600 cal. yr BP (AVP I). Time-series analyses show that Fagus expanded after forest fires decreased during FIM I, and human impact likely contributed to the F. sylvatica population expansions at the two sites during FIM II and AVP I. The comparison with independent climatic records suggests that favourable climatic conditions (eg, cool and wet) were a determining factor. Our study suggests that the expansion of F. sylvatica populations has been triggered by more than one single factor alone.

Postglacial vegetation history as recorded from the subalpine Lake Ribno (NW Rila Mts), Bulgaria

“…At least in the lower mountain ranges of Southwestern Bulgaria, the spread of Fagus in place of the coniferous Pinus-Abies communities was favoured by anthropogenic activities [14,50]. This evidence is in accordance with the estimations of Giesecke et al [51] for the lowlands of Central Europe and for the southern Prealps [52], where disturbance and anthropogenic clearance accelerated the growth of Fagus sylvatica populations during the Holocene. In many areas of Romania, the increase of Fagus was most likely climatically driven ca.…”

Climate and vegetation changes during the Lateglacial and early–middle Holocene at Lake Ledro (southern Alps, Italy)

“…1000 mm. Location of pollen sites discussed in the paper for the Alps and northern Italy -1: Lake Lavarone (Filippi et al, 2007); 2: Lake Lucone ; 3: Passo del Tonale (Gehrig, 1997); 4: Valle di Sol (Favilli et al, 2010); 5: Lake Tovel (Gottardini et al, 2004); 6: Palù di Sonico (Gehrig, 1997); 7: Pian di Gembro (Pini, 2002); 8: Totenmoos (Heiss et al, 2005); 9: Palughetto Cansiglio Plateau (Vescovi et al, 2007); 10: Lago di Fimon (Valsecchi et al, 2008); 11: Lago della Costa (Kaltenrieder et al, 2009(Kaltenrieder et al, , 2010; 12: Lago di Annone (Wick and Möhl, 2006); 13: Lej da San Murezzan (Gobet et al, 2003); 14: Lago Ragogna (Monegato et al, 2007); 15: Lago di Origlio (Tinner et al, 1999); 16: Balladrum (Hofstetter et al, 2006); 17: Piano ; 18: Gerzensee (Lotter et al, 2000); 19: Soppensee (Lotter, 1999); 20: Lobsigensee (Tinner and Vescovi, 2005); 21: Lago Piccolo di Avigliana ; 22: Lago del Greppo ; 23: Lago dell'Accesa (Drescher-Schneider et al, 2007). (c) Catchment area of Lake Ledro (dotted line).…”

“…Recent palynological and anthracological records have pointed out the need to disentangle climate and human influences (e.g. Tinner et al, 2003;Valsecchi et al, 2008Cruise et al, 2009;. In the open debate to assess the possible relationships between climatic change and impact of human societies, which has become a contemporary issue, palaeoenvironmental records are needed to gain a perspective of past processes.…”

Heathlands, fire and grazing. A palaeoenvironmental view of Las Hurdes (Cáceres, Spain) history during the last 1200 years

“…Moreover, beech seeds are mainly dispersed by birds (Valsecchi et al, 2008), allowing its expansion in a pattern of isolated stands, whose signal shows a sporadic and intermittent character (López Merino et al, 2008). This constitutes a problem when detecting possible expansion routes of beech from East to West (Martínez Atienza and Morla Juaristi, 1992;Costa Tenorio et al, 1997), since there is no gradation in the presence of pollen.…”