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Phytolith analysis reveals the intensity of past land use change in the Western Ghats biodiversity hotspot

Phytolith analysis reveals the intensity of past land use change in the Western Ghats biodiversity hotspot
Phytolith analysis reveals the intensity of past land use change in the Western Ghats biodiversity hotspot
This paper presents a study of phytoliths (opal silica bodies from plants) from sediment sequences obtained from two tropical forest patches in the Western Ghats of India: a sacred grove (sequence covers last 550 cal BP) and a forest patch in a plantation (sequence covers last 7500 cal BP). The sites are located at mid-elevation (c. 650–1400 m above sea level) in a mosaic landscape showing anthropogenic open habitats and plantations as well as some evergreen forests. The aim of this paper is to evaluate the landscape composition of grassland and forest over time in the region, grassland being invariably shaped by anthropogenic activities, particularly fire for cultivation. We identified and classified phytoliths into 34 morphotypes from five taxonomic groups: Poaceae (grasses), Cyperaceae (sedges), Arecaceae (palms), Pteridopsida (ferns) and woody dicotyledons (broad-leaved trees and shrubs). We also calculated the humidity–aridity index (Iph). First, our results show that grasses are the most represented phytolith types in both sites, followed by broad-leaved trees and shrubs, palms, sedges, and ferns. Second, the highly variable climatic index Iph over the last 1000 years suggest that changes in phytolith percentage (e.g. broad-leaved trees) might be caused by human agro-pastoral activities, such as clearing through fires and irrigation. Prior to these human activities, the phytolith signal for early Holocene climate is congruent with the existing literature. Finally, this study compares new phytolith results with previous pollen data from the same sites. We find good agreement between these two botanical proxies throughout, thus validating our findings. We provide important evidence regarding the history of environmental change due to anthropogenic activities in the Western Ghats. This has important implications because it provides insights into how tropical forest will respond to increased intensity of human activities.
1040-6182
1-8
Nogue, Sandra
5b464cff-a158-481f-8b7f-647c93d7a034
Whicher, Katie
1a63f4e2-f7ea-4203-87db-2d114c2884cc
Baker, Ambroise G.
8ef5eddb-4637-4567-bb69-b10b07eb3bf2
Bhagwat, Shonil A.
394d7c39-9728-42f4-9bab-a1a336025860
Willis, Kathy J.
624f209e-f827-49b2-b703-dd10841aff33
Nogue, Sandra
5b464cff-a158-481f-8b7f-647c93d7a034
Whicher, Katie
1a63f4e2-f7ea-4203-87db-2d114c2884cc
Baker, Ambroise G.
8ef5eddb-4637-4567-bb69-b10b07eb3bf2
Bhagwat, Shonil A.
394d7c39-9728-42f4-9bab-a1a336025860
Willis, Kathy J.
624f209e-f827-49b2-b703-dd10841aff33

Nogue, Sandra, Whicher, Katie, Baker, Ambroise G., Bhagwat, Shonil A. and Willis, Kathy J. (2016) Phytolith analysis reveals the intensity of past land use change in the Western Ghats biodiversity hotspot. Quaternary International, 1-8. (doi:10.1016/j.quaint.2015.11.113).

Record type: Article

Abstract

This paper presents a study of phytoliths (opal silica bodies from plants) from sediment sequences obtained from two tropical forest patches in the Western Ghats of India: a sacred grove (sequence covers last 550 cal BP) and a forest patch in a plantation (sequence covers last 7500 cal BP). The sites are located at mid-elevation (c. 650–1400 m above sea level) in a mosaic landscape showing anthropogenic open habitats and plantations as well as some evergreen forests. The aim of this paper is to evaluate the landscape composition of grassland and forest over time in the region, grassland being invariably shaped by anthropogenic activities, particularly fire for cultivation. We identified and classified phytoliths into 34 morphotypes from five taxonomic groups: Poaceae (grasses), Cyperaceae (sedges), Arecaceae (palms), Pteridopsida (ferns) and woody dicotyledons (broad-leaved trees and shrubs). We also calculated the humidity–aridity index (Iph). First, our results show that grasses are the most represented phytolith types in both sites, followed by broad-leaved trees and shrubs, palms, sedges, and ferns. Second, the highly variable climatic index Iph over the last 1000 years suggest that changes in phytolith percentage (e.g. broad-leaved trees) might be caused by human agro-pastoral activities, such as clearing through fires and irrigation. Prior to these human activities, the phytolith signal for early Holocene climate is congruent with the existing literature. Finally, this study compares new phytolith results with previous pollen data from the same sites. We find good agreement between these two botanical proxies throughout, thus validating our findings. We provide important evidence regarding the history of environmental change due to anthropogenic activities in the Western Ghats. This has important implications because it provides insights into how tropical forest will respond to increased intensity of human activities.

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More information

Accepted/In Press date: 22 November 2015
e-pub ahead of print date: 8 March 2016
Organisations: Palaeoenvironment Laboratory (PLUS)

Identifiers

Local EPrints ID: 393718
URI: http://eprints.soton.ac.uk/id/eprint/393718
ISSN: 1040-6182
PURE UUID: 774072db-a4ee-4f33-af48-703577010ef0
ORCID for Sandra Nogue: ORCID iD orcid.org/0000-0003-0093-4252

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Date deposited: 03 May 2016 12:58
Last modified: 15 Mar 2024 05:32

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Contributors

Author: Sandra Nogue ORCID iD
Author: Katie Whicher
Author: Ambroise G. Baker
Author: Shonil A. Bhagwat
Author: Kathy J. Willis

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