What is the Holocene? The last 11,800 years Oxygen Isotope Stage - - PowerPoint PPT Presentation

What is the Holocene?

• The last 11,800 years
• Oxygen Isotope Stage 1 (warm interglacial)
• Clear

indications

• f

human impact

• n

the environment

• Development of agriculture/urbanisation

What is the Quaternary?

• Since at least the nineteenth century, different

groups of geologists have used conflicting terms to describe the recent past. Some simply describe the past 23 million years as the Neogene

• period. But others invoke an extra period — the

Quaternary — which follows the Neogene and began around 2 million years ago.

• The last 2.588 million years

The lead up to the Holocene

Climate and the Holocene

Abrupt Climate Change Events

Case Studies….

Kuk Swamp Lake Euramoo Bega Swamp

Case Study…. Tropical Rain Forest of Northern Australia

• The rainforest vegetation includes mixtures with sclerophyll

tree species that occur as emergent and co-dominant species in the canopy. Fringing the rainforests are areas of tall, open forest and tall, medium and low woodland.

• The palaeoecological record is from Lake Euramoo, a small

crater lake at 730 masl near the boundary of sub-montane rainforest and schlerophyll woodland.

Depth m A g e ( c a l y r B P ) R A I N F O R E S T G Y M N O S P E R M S R A I N F O R E S T A N G I O S P E R M S S C H L E R O P H Y L L W O O D L A N D H E R B S I N T R O D U C E D P a l a e

• d

i v e r s i t y 16 17 18 19 20 21 22 23 24 1 2 6 3 4 5 7 8 9 10 12 14 16 18 20 22 C h a r c

• a

l d e n s i t y R a t e

• f

C h a n g e

Eu-1 Eu-2 Eu-3 Eu-4 Eu-5

Z

• n

e s

• 22-15ka:
• Cold/Dry Schlerophyll Woodland
• Low turnover

Tropical Rain Forest of Northern Australia

Lake Euramoo

Depth m A g e ( c a l y r B P ) R A I N F O R E S T G Y M N O S P E R M S R A I N F O R E S T A N G I O S P E R M S S C H L E R O P H Y L L W O O D L A N D H E R B S I N T R O D U C E D P a l a e

• d

i v e r s i t y 16 17 18 19 20 21 22 23 24 1 2 6 3 4 5 7 8 9 10 12 14 16 18 20 22 C h a r c

• a

l d e n s i t y R a t e

• f

C h a n g e

Eu-1 Eu-2 Eu-3 Eu-4 Eu-5

Z

• n

e s

• 15-8.3ka:
• Mosiac Schlerophyll Woodland-

Sub-Montane Rain Forest

• Punctuated high turnover

episodes

Tropical Rain Forest of Northern Australia

Lake Euramoo

Depth m A g e ( c a l y r B P ) R A I N F O R E S T G Y M N O S P E R M S R A I N F O R E S T A N G I O S P E R M S S C H L E R O P H Y L L W O O D L A N D H E R B S I N T R O D U C E D P a l a e

• d

i v e r s i t y 16 17 18 19 20 21 22 23 24 1 2 6 3 4 5 7 8 9 10 12 14 16 18 20 22 C h a r c

• a

l d e n s i t y R a t e

• f

C h a n g e

Eu-1 Eu-2 Eu-3 Eu-4 Eu-5

Z

• n

e s

• 8.3-4.8ka:
• Warm Sub-Montane Rain Forest
• Very low turnover

Tropical Rain Forest of Northern Australia

Lake Euramoo

Depth m A g e ( c a l y r B P ) R A I N F O R E S T G Y M N O S P E R M S R A I N F O R E S T A N G I O S P E R M S S C H L E R O P H Y L L W O O D L A N D H E R B S I N T R O D U C E D P a l a e

• d

i v e r s i t y 16 17 18 19 20 21 22 23 24 1 2 6 3 4 5 7 8 9 10 12 14 16 18 20 22 C h a r c

• a

l d e n s i t y R a t e

• f

C h a n g e

Eu-1 Eu-2 Eu-3 Eu-4 Eu-5

Z

• n

e s

• 4.8-0.12ka:
• Cool/Dry Sub-Montane Rain

Forest with increasing turnover

• Loss of long-lived trees

(eg Agathis)

Tropical Rain Forest of Northern Australia

Lake Euramoo

Depth m A g e ( c a l y r B P ) R A I N F O R E S T G Y M N O S P E R M S R A I N F O R E S T A N G I O S P E R M S S C H L E R O P H Y L L W O O D L A N D H E R B S I N T R O D U C E D P a l a e

• d

i v e r s i t y 16 17 18 19 20 21 22 23 24 1 2 6 3 4 5 7 8 9 10 12 14 16 18 20 22 C h a r c

• a

l d e n s i t y R a t e

• f

C h a n g e

Eu-1 Eu-2 Eu-3 Eu-4 Eu-5

Z

• n

e s

• Last 120 years:
• Cold/Dry Sub-Montane

Rain Forest with High Turnover

• Invasion of exotic plants

Tropical Rain Forest of Northern Australia

Lake Euramoo

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Podo carpus Pomaderris Eucalyptus type 1 Eucalyptus cf. pauciflora Eucalyptus type 2 Acacia Callitris Casuarina Epacr is type Kunzea type Le ptospermum Monolete Fe rn spores Ble chnum Poaceae Tu bulifl o ra e Char coal (>5 m) µ

Age (years BP)

Bega Swamp 1025 m, Southern New South Wales

• Increase disturbance frequency

post 5000 yr BP ⇒ higher turnover rates ⇒ loss of large long-lived trees ⇒ internal fragmentation alters species composition ⇒ greater opportunity for invasion by fast growing plants (eg. gap-dependent species, weeds and lianas)

Implications of long-term increases in disturbance for rain forest ecosystems

Phillips et al. (2002) Nature 418, 770-774

Origins of Agriculture Origins of Agriculture

• Archaeological and

Archaeological and palaeoecological palaeoecological studies have revealed at least studies have revealed at least 10 independent centres of food production. 10 independent centres of food production.

• New Guinea has been considered a “secondary centre, where

New Guinea has been considered a “secondary centre, where agricultural development was derived from or triggered by the ar agricultural development was derived from or triggered by the arrival rival

• f domesticates from Southeast Asia.
• f domesticates from Southeast Asia.

Centres of Centres of

• rigin
• rigin
• f food
• f food

production production

Two Hypotheses

1.

• 1. DISPERSAL

DISPERSAL: Domesticated plants (taro, bananas, sago, sugarcane) : Domesticated plants (taro, bananas, sago, sugarcane) and animals (pig, chicken) were dispersed from Southeast Asia as and animals (pig, chicken) were dispersed from Southeast Asia as part part

• f the migration of “
• f the migration of “Austronesian

Austronesian” speakers around 4000 yr BP into the ” speakers around 4000 yr BP into the Pacific and Indian Oceans. Pacific and Indian Oceans.

Two Hypotheses

2.

• 2. INDEPENDENT INVENTION:

INDEPENDENT INVENTION: New Guinea was a primary centre for agricultural development and New Guinea was a primary centre for agricultural development and plant domestication prior to any known influence from South plant domestication prior to any known influence from Southeast Asia east Asia (prior to 4000 yr BP). (prior to 4000 yr BP).

The Highland Valleys The Highland Valleys

The highland valleys are found The highland valleys are found along the main cordillera of inland along the main cordillera of inland New Guinea between an altitude of New Guinea between an altitude of 1200 1200 – – 2000 m 2000 m asl

• asl. Intensive

. Intensive agriculture supports a population agriculture supports a population

• f over 3 million people there
• f over 3 million people there

today. today.

h

Kuk Kuk Swamp Swamp

10 9 8 7 6 5 4 3 2 1 Cal Cal kyr kyr BP BP

I II III IV V&VI

Archaeological Evidence for Archaeological Evidence for Agriculture: Agriculture: Kuk Kuk Swamp Swamp

Phase Phase

• Plant exploitation and some cultivation occurred on the wetland

Plant exploitation and some cultivation occurred on the wetland margin at 10200 cal BP (Phase I) margin at 10200 cal BP (Phase I)

• Mounding cultivation began by 7000 cal BP (Phase II)

Mounding cultivation began by 7000 cal BP (Phase II)

• Ditched cultivation began by 4350 cal yr BP (Phase III).

Ditched cultivation began by 4350 cal yr BP (Phase III).

Anthropogenic Indicators in Anthropogenic Indicators in New Guinea New Guinea

Kuk Kuk Swamp Pollen Record: Swamp Pollen Record: LGM LGM-

• Present

Present

15 80 60 40 20

Black clay Phase 3 Grey-brown clay Phase 2 Phase 1 Late Pleistocene peat

20 10 5

Calibrated Radiocarbon Date BP (x1000) >15 9.9-10.2 7.4 9.9 6.5-7.0 2.8-4.8 2.5 Archaeostratigraphy

Pollen and Spores

(% total sum)

Musaceae

(% phytolith sum) Ensete Eumusa Musa ingens

• Forest decline is not synchronous across the highlands.

Forest decline is not synchronous across the highlands.

h h h h h Baliem Telefomin Nurenk Kainantu Tari

2 4 6 8 10 12 50 100

%

Arboreal Pollen

Age (10 yr B.P .)

3

2 4 6 8 10 12 60

Swamp Myrtaceae

Age (10 yr B.P .)

3

Non Non-

• Synchronous Forest

Synchronous Forest Clearance in the Mid Clearance in the Mid-

• Late Holocene

Late Holocene

h

8ka 7ka 3ka 4ka 2ka 7ka

• An increased focus on wetland cultivation during the mid

An increased focus on wetland cultivation during the mid-

• late Holocene led

late Holocene led to rapid clearance of forests, particularly swamp forest enviro to rapid clearance of forests, particularly swamp forest environments. nments.

• Evidence for agriculture by at least 7000 cal yr BP (and possibl

Evidence for agriculture by at least 7000 cal yr BP (and possibly as y as early as 7800 cal yr BP) is consistent with two indicators for early as 7800 cal yr BP) is consistent with two indicators for anthropogenic activity anthropogenic activity… …(i) appearance in fossil record of cultivated (i) appearance in fossil record of cultivated species, and (ii) non species, and (ii) non-

• synchronous forest loss across the highlands.

synchronous forest loss across the highlands.

• At

At Kuk Kuk Swamp clearance of lower Swamp clearance of lower montane montane rain forests rain forests commenced in the Early Holocene with modification to grassland commenced in the Early Holocene with modification to grassland and cultivation of bananas by 7000 cal BP. and cultivation of bananas by 7000 cal BP.

• Agriculture arose independently in New Guinea between

Agriculture arose independently in New Guinea between 7800 7800-

• 7000 cal BP, more than 3000 years before any known

7000 cal BP, more than 3000 years before any known influence from Southeast Asia. influence from Southeast Asia.

Conclusions Conclusions