Vegetation and Climate Changes during the Bronze and Iron Ages (~3600–600 BCE) in the Southern Levant Based on Palynological Records

TLDR: The role of climate fluctuations in shaping southern Levantine human history from 3600 to 600 BCE (the Bronze and Iron Ages) as evidenced in palynological studies was presented in this paper.

Abstract: This article presents the role of climate fluctuations in shaping southern Levantine human history from 3600 to 600 BCE (the Bronze and Iron Ages) as evidenced in palynological studies. This time interval is critical in the history of the region; it includes two phases of rise and decline of urban life, organization of the first territorial kingdoms, and domination of the area by great Ancient Near Eastern empires. The study is based on a comparison of several fossil pollen records that span a north-south transect of 220 km along the southern Levant: Birkat Ram in the northern Golan Heights, Sea of Galilee, and Ein Feshkha and Ze’elim Gully both on the western shore of the Dead Sea. The vegetation history and its climatic implications are as follows: during the Early Bronze Age I (~3600–3000 BCE) climate conditions were wet; a minor reduction in humidity was documented during the Early Bronze Age II–III (~3000–2500 BCE). The Intermediate Bronze Age (~2500–1950 BCE) was characterized by moderate climate conditions, however, since ~2000 BCE and during the Middle Bronze Age I (~1950–1750 BCE) drier climate conditions were prevalent, while the Middle Bronze Age II–III (~1750–1550 BCE) was comparably wet. Humid conditions continued in the early phases of the Late Bronze Age, while towards the end of the period and down to ~1100 BCE the area features the driest climate conditions in the timespan reported here; this observation is based on the dramatic decrease in arboreal vegetation. During the period of ~1100–750 BCE, which covers most of the Iron Age I (~1150–950 BCE) and the Iron Age IIA (~950–780 BCE), an increase in Mediterranean trees was documented, representing wetter climate conditions, which followed the severe dry phase of the end of the Late Bronze Age. The decrease in arboreal percentages, which characterize the Iron Age IIB (~780–680 BCE) and Iron Age IIC (~680–586 BCE), could have been caused by anthropogenic activity and/or might have derived from slightly drier climate conditions. Variations in the distribution of cultivated olive trees along the different periods resulted from human preference and/or changes in the available moisture. DOI: 10.2458/azu_rc.57.18555

Figures

Figure 3 Simplified pollen diagram of the Sea of Galilee record during the Bronze and Iron Ages. A 10-fold exaggeration is used to show changes in low taxa percentages. The palynological diagram was divided into five main groups based on taxa geographical origin and on ecological and cultural characteristics (see online Appendix). EB = Early Bronze Age; IB = Intermediate Bronze Age; MB = Middle Bronze Age; LB = Late Bronze Age; IA = Iron Age.

Figure 5 Summary of the climate history of the southern Levant during the Bronze and Iron Ages based on the palynological evidence.

Figure 2 The catchment area of the Sea of Galilee and the Dead Sea with the watershed divide line of the region.

Figure 1 (a) Rainfall isohyets of the south Levantine region (after Srebro and Soffer 2011), with the location of the four fossil pollen records discussed in this paper: 1. Birkat-Ram (Schwab et al. 2004; Neumann et al. 2007b); 2. Sea of Galilee (Langgut et al. 2013; this study, Figure 3); 3. Ein Feshkha (Neumann et al. 2007a, 2009), and 4. Ze’elim Gully (Neumann et al. 2007a; Langgut et al. 2014a); (b) the position of the southern Levant in the Eastern Mediterranean; (c) phytogeographic zones.

Full text

VEGETATION AND CLIMATE CHANGES DURING THE BRONZE AND IRON AGES
(~3600–600 BCE) IN THE SOUTHERN LEVANT BASED ON PALYNOLOGICAL
RECORDS
Dafna Langgut
1
• Israel Finkelstein
2
• Thomas Litt
3
• Frank Harald Neumann
4
• Mordechai Stein
5
ABSTRACT. This article presents the role of climate uctuations in shaping southern Levantine human history from 3600
to 600 BCE (the Bronze and Iron Ages) as evidenced in palynological studies. This time interval is critical in the history
of the region; it includes two phases of rise and decline of urban life, organization of the rst territorial kingdoms, and
domination of the area by great Ancient Near Eastern empires. The study is based on a comparison of several fossil pollen
records that span a north-south transect of 220 km along the southern Levant: Birkat Ram in the northern Golan Heights,
Sea of Galilee, and Ein Feshkha and Ze’elim Gully both on the western shore of the Dead Sea. The vegetation history and
its climatic implications are as follows: during the Early Bronze Age I (~3600–3000 BCE) climate conditions were wet; a
minor reduction in humidity was documented during the Early Bronze Age II–III (~3000–2500 BCE). The Intermediate
Bronze Age (~2500–1950 BCE) was characterized by moderate climate conditions, however, since ~2000 BCE and during
the Middle Bronze Age I (~1950–1750 BCE) drier climate conditions were prevalent, while the Middle Bronze Age II–III
(~1750–1550 BCE) was comparably wet. Humid conditions continued in the early phases of the Late Bronze Age, while
towards the end of the period and down to ~1100 BCE the area features the driest climate conditions in the timespan report-
ed here; this observation is based on the dramatic decrease in arboreal vegetation. During the period of ~1100–750 BCE,
which covers most of the Iron Age I (~1150–950 BCE) and the Iron Age IIA (~950–780 BCE), an increase in Mediterranean
trees was documented, representing wetter climate conditions, which followed the severe dry phase of the end of the Late
Bronze Age. The decrease in arboreal percentages, which characterize the Iron Age IIB (~780–680 BCE) and Iron Age IIC
(~680–586 BCE), could have been caused by anthropogenic activity and/or might have derived from slightly drier climate
conditions. Variations in the distribution of cultivated olive trees along the different periods resulted from human preference
and/or changes in the available moisture.
INTRODUCTION
Due to the occurrence of different vegetation zones that follow steep north-south and west-east
precipitation gradients, the southern Levant is a sensitive region for tracing links between climate
and cultural changes, featuring Mediterranean (precipitation >400 mm/yr), semi-arid steppe Irano–
Turanian (~400–200 mm/yr), and desert Saharo–Arabian (precipitation <200 mm/yr) zones (Zohary
1973, 1982; Figure 1). The region went through signicant changes in climate patterns during the
Late Holocene. These changes were accompanied by transformations in settlement and demograph-
ic patterns (e.g. Migowski et al. 2006; Neumann et al. 2007a; Kaniewski et al. 2010; Litt et al.
2012; Langgut et al. 2013). The question of how environmental changes affected human activity in
this area in antiquity has been debated (compare Rambeau 2010). This article includes the results
of recent research efforts to establish the vegetation history of the Bronze and Iron Ages (~3600–
600 BCE) based on high-resolution and well-dated fossil pollen records. This time interval features
cycles of rise and fall of urban cultures, the emergence and collapse of the territorial kingdoms
documented in the Hebrew Bible and other Ancient Near Eastern records, and periods of imperial
rule. It also features sharp settlement oscillations, including human movements between the Med-
iterranean, semi-arid, and desert environments that could have resulted from climate uctuations.
The study of fossil pollen grains is a powerful tool in the reconstruction of past vegetation and cli-
mate history (e.g. Bryant 1989). Several palynological records that cover the Bronze and Iron Ages
are available for the southern Levant. Four of them are presented and discussed below (Figure 1):
1. Laboratory for Archaeobotany and Ancient Environments, Institute of Archaeology, Tel Aviv University,
P.O. Box 39040, Tel Aviv 6997801, Israel. Corresponding author. Email: langgut@post.tau.ac.il.
2. Institute of Archaeology, Tel Aviv University, Tel Aviv 6997801, Israel.
3. Steinmann Institute of Geology, Mineralogy and Paleontology, University of Bonn, Nussallee 8, 53115 Bonn, Germany.
4. Forschungsstelle für Paläobotanik, Westfälische Wilhelms-Universität Münster, Heisenbergstr. 2, 48149 Münster, Germany.
5. Geological Survey of Israel, 30 Malkhe Israel St., Jerusalem 95501, Israel.
Radiocarbon, Vol 57, Nr 2, 2015, p 217–235 DOI: 10.2458/azu_rc.57.18555
© 2015 by the Arizona Board of Regents on behalf of the University of Arizona
The Iron Age in Israel: The Exact and Life Sciences Perspective
Edited by Israel Finkelstein, Steve Weiner, and Elisabetta Boaretto

218
D Langgut et al.
Birkat Ram (Schwab et al. 2004; Neumann et al. 2007b), Sea of Galilee (Langgut et al. 2013; this
study), Ein Feshkha (Neumann et al. 2007a, 2009), and Ze’elim Gully (Neumann et al. 2007a;
Langgut et al. 2014a). These records were chosen because of their relatively robust chronological
framework and high pollen sampling resolution (only a few decades interval between samples).
Other pollen diagrams from the region are not presented here since they were either sampled in
Figure 1 (a) Rainfall isohyets of the south Levantine region (after Srebro and Soffer 2011), with the location
of the four fossil pollen records discussed in this paper: 1. Birkat-Ram (Schwab et al. 2004; Neumann et al.
2007b); 2. Sea of Galilee (Langgut et al. 2013; this study, Figure 3); 3. Ein Feshkha (Neumann et al. 2007a,
2009), and 4. Ze’elim Gully (Neumann et al. 2007a; Langgut et al. 2014a); (b) the position of the southern
Levant in the Eastern Mediterranean; (c) phytogeographic zones.

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Vegetation, Climate Changes during Bronze–Iron Ages in Southern Levant
lower resolution [e.g. Litt et al. (2012) at the Dead Sea analyzed samples in ~180/200-yr intervals
between samples], and/or because they suffer from chronological uncertainties (Baruch 1986, 1990,
1993; Baruch and Bottema 1999; van Zeist et al. 2009; several studies discuss the chronological
problems of some of the pollen diagrams from the region, e.g. Cappers et al. 1998; Meadows 2005;
Neumann et al. 2010).
This study therefore spans a north-south transect of 220 km of the southern Levant, which features
a north-south precipitation gradient of ~1000 mm of annual rainfall as well as a sharp topographic
gradient. While Birkat Ram, located in a volcanic maar, is located at 940 m above msl (mean sea
level), the Sea of Galilee and the Dead Sea—which comprise morphotectonic depressions along the
Dead Sea Transform (Neev and Emery 1995; Stein 2001, 2014a,b)—are situated at 200 and 400 m
below sea level (m bsl), respectively.
In addition to paleoclimate reconstruction, this research also aims at tracing evidence of human
interference in natural vegetation as reected in the pollen curves: agricultural activity, grazing,
deforestation, abandonment of elds, and soil erosion.
CURRENT CLIMATE AND VEGETATION
Annual rainfall in the southern Levant is high on the coast and in the north, and diminishes to the
south and east (Ziv et al. 2006; Dayan et al. 2007), where the north Sinai coastline forms the south-
ern limit in which rain clouds can form in large masses (Zangvil and Druian 1990). East of the Med-
iterranean, the inuence of the Mediterranean humidity drops sharply, also due to the orographic ef-
fect of the mountain ranges, which create a rain shadow, the Judean Desert. As a result, the southern
Levant is composed of three main phytogeographical zones (Zohary 1962, 1973) (Figure 1b): (1)
the Mediterranean, (2) the Irano–Turanian, and (3) the Saharo–Arabian (which also includes some
tropical plants that belong to the Sudanian vegetation).
1. The Mediterranean region runs along the coast and its adjacent mountainous areas (Galilee,
Carmel Ridge, Samaria, and Judea). This vegetation zone features Mediterranean maquis/forest
with typical evergreen trees such as Quercus callipprinos, Olea europaea, and Pinus halepensis
and some deciduous trees (e.g. Quercus boissieri, Q. ithaburensis, and Pistacia palaestina). In
the understory of forests or in open elds, dwarf-shrubs as well as many herbaceous species
are common. This territory receives more than 400 mm rainfall annually and is generally inu-
enced by the Mediterranean climatic system together with some regional orographic phenome-
na. The Israeli coastal plain occupies a mix of Mediterranean and desert plants due to its sandy
soil and saline environment. This sandy strip is dominated by different species of Poaceae,
Chenopodiaceae, Artemisia monosperma, and Ephedra.
2. The Irano–Turanian phytogeographic region runs from the coastal plain near Gaza to the Negev
Highlands and the southern edge of the Judean Highlands and then continues northward via the
central Jordan Valley to the Sea of Galilee. This is an almost tree-less landscape with semi-arid
vegetation, often described as steppe. Different species of Poaceae and Chenopodiaceae are the
main vegetal components of this region as well as Artemisia herba-alba. The annual rainfall is
200–400 mm on average and is due mainly to western Mediterranean depressions. The region
is also characterized by relatively broad seasonal and daily temperature distributions.
3. The Saharo–Arabian territory occupies most of the Negev Desert, which lies within the world
desert belt (30°N). The vegetation is typied by relatively low species diversity and is domi-
nated by many members of the Chenopodiaceae, Zygophyllum dumosum, grasses, and Tamarix
spp. This region has a typical desert climate: the mean annual rainfall does not exceed 200 mm

220
D Langgut et al.
and is usually lower than 100 mm. Seasonal and daily temperature distributions are broad. This
zone is inuenced by southern and southeastern synoptic systems, which are widespread in the
spring and autumn, as well as by the western Mediterranean depressions, which mainly inu-
ence the northern part of the Negev Desert. Within these desert plants’ geographical area, the
Sudanian territory with tropical elements occurs along the shores of the Dead Sea, in the Arabah
Valley and in the central Jordan Valley (up to ~80 km north of the Dead Sea). Some of the trop-
ical plants are linked to freshwater springs or wadi beds; they include Acacia, Ziziphus spina-
christi, and Salvadora persica (Zohary 1962; Shmida and Or 1983; Al-Eisawi 1996).
SOUTHERN LEVANT POLLEN RECORDS
Birkat Ram
Birkat Ram, in the foothills of Mount Hermon, comprises a small maar lake that has occupied this
volcanic depression since the last interglacial period (the TAHAL borehole, which was performed
in 1968, penetrated 120 m and reached the basaltic ow at the bottom of the lacustrine sequence;
Singer and Ehrlich 1978). The paleohydrological importance of Birkat Ram stems from its being a
“sampler” of the Mount Hermon hydrological system; in general, maar lakes comprises a “delicate”
regional tracer because of the lack of input water from major river and streams (e.g. Lamb et al.
2000; Lamb 2001). In 1999, a joint team of GFZ-Potsdam and the Hebrew University carried out
several drills under water at a depth of 1.5 m (Schwab et al. 2004). This very shallow depth could not
support deep drilling and the expedition yielded cores that were only several meters long. They were
used to prepare a 543-cm-long composite prole. Correlations between the cores were established
by high-resolution magnetic susceptibility, which was independently improved by palynological
observations (Schwab et al. 2004; Neumann et al. 2007b). The compiled sedimentary record is
characterized by a relatively homogenous lithology of detrital marls and diatoms. Eighteen samples
of organic debris were accelerator mass spectrometry (AMS) radiocarbon dated and a chronological
framework was established from ~4500 BCE to modern times (Schwab et al. 2004; Neumann et al.
2007b). The palynological investigation was conducted at an average sample interval of ~4 cm from
the Bronze to the Iron Ages. Considering a uniform sedimentation rate in the composite core, this
would imply that every sample represents on average 75 yr.
Sea of Galilee (Lake Kinneret)
The Sea of Galilee receives its water from the Jordan River and some other shorter rivers running
from the Galilee Mountains and the Golan Heights (Figure 2). The southern part of the lake com-
prises a shallow body of water, a few meters deep, while the northern part (where Research Station
A is located) reaches a water depth of 40 m. During most of the Holocene, the Sea of Galilee stood
at ~212 m bsl, yet there were periods when the lake level declined and the shallower southern part
was exposed (Hazan et al. 2005; Stein 2014a). However, no evidence exists for a full desiccation of
the lake during the past 10,000 yr. Thus, it appears that sedimentation in its northern part has been
continuous.
The drilling campaign performed during the spring of 2010 recovered an 18-m core from the bottom
of the lake near Research Station A. Details on the description of the compiled cores are given by
Schiebel (2013).
14
C dating of organic debris from the core indicates that the drilled sediment se-
quence covers almost the entire Holocene (Schiebel 2013). The time interval of the Bronze to Iron
Ages comprises 5.5 m of the 18-m prole, and is characterized by a relatively homogenous lithol-
ogy. This specic interval (composite depth of 458.8–1006.6 cm) was sampled for palynological
analysis at 10-cm intervals (a total of 56 samples). A concise palynological diagram of the Bronze
and Iron Ages was presented by Langgut et al. (2013); a more detailed diagram is given in Figure 3

221
Vegetation, Climate Changes during Bronze–Iron Ages in Southern Levant
and the online Appendix. Six samples of terrestrial, short-lived organic debris were extracted from
the Bronze and Iron Age sediment section and were AMS
14
C dated. The chronology (age-depth
model) is presented in Langgut et al. (2013), which covers the time interval of 3150–500 BCE.
Assuming a uniform sedimentation rate in this interval, the resolution of the palynological sampling
would be a sample per ~40 yr.
Figure 2 The catchment area of the Sea of
Galilee and the Dead Sea with the watershed
divide line of the region.

Frequently asked questions

Q1. What are the contributions in "Vegetation and climate changes during the bronze and iron ages (~3600–600 bce) in the southern levant based on palynological records" ?

This article presents the role of climate fluctuations in shaping southern Levantine human history from 3600 to 600 BCE ( the Bronze and Iron Ages ) as evidenced in palynological studies. The study is based on a comparison of several fossil pollen records that span a north-south transect of 220 km along the southern Levant: Birkat Ram in the northern Golan Heights, Sea of Galilee, and Ein Feshkha and Ze ’ elim Gully both on the western shore of the Dead Sea. The vegetation history and its climatic implications are as follows: during the Early Bronze Age I ( ~3600–3000 BCE ) climate conditions were wet ; a minor reduction in humidity was documented during the Early Bronze Age II–III ( ~3000–2500 BCE ). Humid conditions continued in the early phases of the Late Bronze Age, while towards the end of the period and down to ~1100 BCE the area features the driest climate conditions in the timespan reported here ; this observation is based on the dramatic decrease in arboreal vegetation. During the period of ~1100–750 BCE, which covers most of the Iron Age I ( ~1150–950 BCE ) and the Iron Age IIA ( ~950–780 BCE ), an increase in Mediterranean trees was documented, representing wetter climate conditions, which followed the severe dry phase of the end of the Late Bronze Age. 

Q2. What is the significance of the olive pollen in the Middle Bronze Age?

Since Olea pollen production has a strong response to cessation (a dramatic decrease in pollen production was documented in deserted orchards after several decades of abandonment; Langgut et al. 2014b), the olive pollen that was identified during the Intermediate Bronze Age represents well-maintained orchards. 

Q3. What caused the settlement system to recover and re-expand in the south?

Wetter conditions in the Middle Bronze Age II–III (~1750–1550 BCE) caused the settlement system to recover and re-expand in the south (in areas such as the Beer Sheba Valley in the northern Negev). 

Q4. What is the significance of the decline in olive pollen?

Since the decreasing olive percentages were not accompanied by a reduction of arboreal pollen, this decline in olive pollen was probably linked to changes in geopolitical (rather than climatic) conditions in the region. 

Q5. What is the evidence for dry climate conditions in the Middle Bronze Age?

Evidence for dry climate conditions in the beginning of Middle Bronze Age and more humid conditions in the later phases is also provided by the lithology of the Ze’elim record, which points to the accumulation of sediments in a shore environment (sands and beach ridge) during the Middle Bronze Age I, and therefore indicates relatively low Dead Sea stands. 

Q6. What is the significance of the drop in the lake levels in the western Dead Sea?

The occurrence of a shore depositional environment in these western Dead Sea margin sites (Ein Gedi, Ein Feshkha, Ze’elim) represents a drop in the Dead Sea lake levels that was most probably the result of reduced precipitation at the end of the Late Bronze Age, mainly in the area of the northern sources of the Dead Sea drainage basin. 

Q7. What is the AMS 14C dating of the lake?

14C dating of organic debris from the core indicates that the drilled sediment sequence covers almost the entire Holocene (Schiebel 2013). 

Q8. Why did the decline in the Mediterranean forest occur?

Because of low settlement activity at that time, shrinkage of the Mediterranean forest was most probably not the result of human pressure. 

Q9. Why is the southern levant a sensitive region for tracing links between climate and cultural?

Due to the occurrence of different vegetation zones that follow steep north-south and west-east precipitation gradients, the southern Levant is a sensitive region for tracing links between climate and cultural changes, featuring Mediterranean (precipitation >400 mm/yr), semi-arid steppe Irano– Turanian (~400–200 mm/yr), and desert Saharo–Arabian (precipitation <200 mm/yr) zones (Zohary 1973, 1982; Figure 1). 

Q10. What is the significance of the pollen diagrams?

In addition to the drier climate conditions that were prevalent at the end of the period based onthe decline in the Mediterranean trees, a slight decrease of Olea pollen and somewhat increase in pine values were identified in two out of the three pollen diagrams available for this period: Birkat Ram and Ze’elim (Figures 4a,d). 

Q11. What is the reason for the decline of olives in the Judean Highlands?

The authors suggest that the high distribution of olive probably reflects human influence in the Judean Highlands rather than increased precipitation, since this Olea peak was not accompanied by any significant rise in other Mediterranean trees. 

Q12. What is the significance of the pollen peak in the southern Judean Highlands?

In the southern record of Ze’elim, an olive pollen peak of maximally 10% of the total pollen was identified around the second part of the Intermediate Bronze Age (~2200–2000 BCE), which probably indicates expansion of olive horticulture in the southern Judean Highlands (Figure 4d). 

Q13. What is the evidence for a decrease in tree values in the Mediterranean?

From the beginning of the period and until about 1800 BCE, Mediterranean tree values remain low, as evidenced by the more “climate-sensitive” pollen records—the Sea of Galilee and Ze’elim—while Birkat Ram does not point to any pronounced climate change. 

Q14. What is the time interval between the Bronze and Iron Ages?

This time interval features cycles of rise and fall of urban cultures, the emergence and collapse of the territorial kingdoms documented in the Hebrew Bible and other Ancient Near Eastern records, and periods of imperial rule. 

Q15. What is the evidence for the revival of the urban system in the northern valleys?

This is evident in the revival of the urban system in the northern valleys (Finkelstein 2003) and in the settlement wave in the highlands, including areas that are amenable to olive orchards (Gal 1992; Finkelstein 1995; Frankel et al. 2001; Zertal 2004, 2007). 

Q16. What is the humid period in the Bronze and Iron Ages?

The Mediterranean arboreal pollen curve, including olive trees, appears in its highest percentages, indicating that the Early Bronze Age The author(~3600–3000 BCE) was the most humid phase in the Bronze and Iron Ages. 

Q17. What is the evidence for the Mediterranean climate during the Middle Bronze Age I?

They also confirm the palynological observation of regional dryness (rather than human-induced changes) during the Middle Bronze Age I. 

Q18. Why are no pollen data available for the Late Bronze Age?

No pollen data for the Late Bronze Age are available from the Ze’elim record (Figure 4d) due to some sedimentary erosion and unfavorable conditions for pollen preservation in sandy sediments (Langgut et al. 2014a).