Holocene vegetational history of the Apuseni ... - geo.edu.ro

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A. Bodnariuc et al. / Quaternary Science Reviews 21 (2002) 1465–1488
Chenopodiaceae and Asteroideae became more frequent.
This early impact is not surprising when
considering <strong>the</strong> situation <strong>of</strong> <strong>the</strong> site along a valley
allowing easy access to <strong>the</strong> flat areas <strong>of</strong> mid elevation.
From <strong>the</strong> available archaeochronological data, this first
presence might be attributed to <strong>the</strong> first Neolithic
occupations in Transylvania (Gura Baciului, Ocna
Sibiului, Starcevo–Cris III–IV Cultures) dated between
7850 and 7350 cal BP (Lazarovici, 1993; Demoulle, 1998;
Mantu, 1998). Settlements <strong>of</strong> <strong>the</strong>se people were present
o100 km from <strong>the</strong> studied area, <strong>the</strong> anthropogenic
indicators suggesting that, at that time, groups had
already begun to travel over <strong>the</strong> mountain. At Bergerie,
during <strong>the</strong> same period, anthropogenic indicators such
as increases in Cichorioideae and Rumex are also found
near 7600 cal BP. The local impact seems limited. The
sedimentation rate which was 0.6 mm/yr between ca
7800 and 7600 cal BP was only 0.17 mm/yr between 7600
and 4570 cal BP.
The age <strong>of</strong> this first palynological evidence <strong>of</strong>
Romanian Neolithic husbandry agrees with <strong>the</strong> presence
<strong>of</strong> numerous dated archaeological sites in <strong>the</strong> Balkans
between 8900 and 6800 cal BP (Willis, 1994; Willis and
Bennett, 1994) and with <strong>the</strong> earliest Neolithic 14 C dates
from <strong>the</strong> nor<strong>the</strong>rn Balkans (8350–7800 cal BP) (Edwards
et al., 1996).
The first Cerealia pollen is noticed at Ic Ponor I
during <strong>the</strong> Neolithic, around 7100 cal BP (6190790 BP).
At <strong>the</strong> same time Artemisia and Poaceae are more
abundant. During <strong>the</strong> same period, several groups are
known in Transylvania near <strong>the</strong> studied zone: Cheile
Turzii-Lumea Noua Complex and Turdas Groups
(Mantu, 1998).
Around 5200–4500 cal BP at Cimeti"ere and Bergerie,
percentages <strong>of</strong> Poaceae and ruderal communities (Chenopodiaceae,
Rumex, Urticaceae) increase as well as
Carpinus and Fagus. At Bergerie during <strong>the</strong> period
4570–4100 cal BP <strong>the</strong> sedimentation rate is 0.71 mm/yr
which is higher than during <strong>the</strong> periods 7600–
4570 cal BP (0.17 mm/yr) and 4100–1935 cal BP
(0.14 mm/yr). The interpretation <strong>of</strong> <strong>the</strong>se changes is
difficult. The changes might be due to <strong>the</strong> climatic
variations which concerned this period in Europe and
determined <strong>the</strong> extension <strong>of</strong> beech (Huntley and
Prentice, 1988; Huntley et al., 1989; Huntley, 1990a, b;
Kelly and Huntley, 1991; Gardner and Willis, 1999). But
<strong>the</strong> consequences <strong>of</strong> human impact should not be
underestimated. In <strong>the</strong> Pyrenees, at mid and low
altitudes (Jalut et al., 1982, 1998; Jalut, 1984; Kenla
and Jalut, 1979) as well as in <strong>the</strong> plains <strong>of</strong> central
Europe (K.uster, 1997) and in <strong>the</strong> Romanian mountains,
<strong>the</strong> abundance <strong>of</strong> Fagus in <strong>the</strong> forests may be partly
related to <strong>the</strong> successive cuttings <strong>of</strong> fir, oak or spruce
forests. At Bergerie, when deforestation increases from
4100 to 1935 cal BP, <strong>the</strong> sedimentation rate decreases
(0.143 mm/yr) <strong>the</strong>n increases between ca 1935 and
680 cal BP (0.24 mm/yr) which renders <strong>the</strong> interpretation
difficult.
At Padis, despite very favourable topographic conditions,
<strong>the</strong>re is no clear palynological evidence for an
early strong local human impact and <strong>the</strong> sedimentological
study <strong>of</strong> <strong>the</strong> core is not informative. The
sedimentation rate stays low all along <strong>the</strong> core (between
0.09 and 0.14 mm/yr from level 90 to level 35). Only <strong>the</strong>
recent Sphagnum peat shows a higher rate (0.78 mm/yr).
At Cimeti"ere, <strong>the</strong> use <strong>of</strong> <strong>the</strong> sedimentological data
might be more informative but <strong>the</strong> lack <strong>of</strong> dates does not
allow calculation <strong>of</strong> <strong>the</strong> sedimentation rate. However,
around 1935 cal BP a relationship exists between <strong>the</strong>
abundance in anthropogenic indicators, <strong>the</strong> decrease in
AP/T values and <strong>the</strong> presence <strong>of</strong> thin layers <strong>of</strong> sand in
<strong>the</strong> peat. They might be <strong>the</strong> consequence <strong>of</strong> erosion
processes related to deforestations. The contemporaneous
decline in <strong>the</strong> pollen concentration reinforces
<strong>the</strong> hypo<strong>the</strong>sis <strong>of</strong> a strong human impact on <strong>the</strong>
landscape.
In <strong>the</strong> three sites, between ca 4500 and 3200–
2750 cal BP <strong>the</strong> forest cover remained stable. Then it
began to regress. The decrease in AP values is correlated
to a rise in Poaceae, Chenopodiaceae and Plantago
species.
At Padis and Bergerie, around 2750–2550 cal BP, <strong>the</strong>
development <strong>of</strong> Poaceae and <strong>the</strong> increase in ruderal
communities (Artemisia, Chenopodiaceae, Rumex, Urticaceae,
Plantago) demonstrate increased human activities.
They rose around 1935 BP and 695–660 cal BP
(presence <strong>of</strong> Cerealia at Cimeti"ere). These periods
correspond to decreases in AP values (Bergerie, Cimeti-
"ere, Padis). Humans gradually spread into <strong>the</strong> mountain
(Obelic et al., 1998).
At <strong>the</strong> same time, human impact affected both
elevations between 1000 and 1400 m and <strong>the</strong> lower
zones. Thus, <strong>the</strong> decrease in percentages and pollen
concentration <strong>of</strong> Carpinus, Quercus, Ulmus and Tilia, is
synchronous with an increase in anthropogenic indicators
and possibly reflects <strong>the</strong> destruction <strong>of</strong> <strong>the</strong>
Querceto–Carpinetum.
The massive forest clearance during <strong>the</strong> last century is
shown by <strong>the</strong> fall in AP values and <strong>the</strong> greater Poaceae
abundance in <strong>the</strong> upper levels <strong>of</strong> most peat bogs. In <strong>the</strong>
studied area <strong>the</strong> present scarcity <strong>of</strong> Abies and <strong>the</strong>
noticeable extension <strong>of</strong> Fagus are probably <strong>the</strong> consequences
<strong>of</strong> this deforestation. In some places such as Ic
Ponor, <strong>the</strong> pollen analysis <strong>of</strong> <strong>the</strong> fifteen upper centimeters
<strong>of</strong> Sphagnum peat shows <strong>the</strong> correlation between
<strong>the</strong> forest destruction and <strong>the</strong> extension <strong>of</strong> <strong>the</strong> cultivated
areas. Cerealia pollen is regularly observed and, in <strong>the</strong>
surface samples, pollen <strong>of</strong> Secale, Fagopyrum, Centaurea
cyanus, Plantago lanceolata, Plantago coronopus and
Fabaceae are well represented. The abundance <strong>of</strong>
Onobrychis pollen type indicates cultivated zones, fallow
land and pathways in <strong>the</strong> close vicinity (Figs. 3 and 4).