The University of Southampton
University of Southampton Institutional Repository

Sunlight mediated seasonality in canopy structure and photosynthetic activity of Amazonian rainforests

Sunlight mediated seasonality in canopy structure and photosynthetic activity of Amazonian rainforests
Sunlight mediated seasonality in canopy structure and photosynthetic activity of Amazonian rainforests
Resolving the debate surrounding the nature and controls of seasonal variation in the structure and metabolism of Amazonian rainforests is critical to understanding their response to climate change. In situ studies have observed higher photosynthetic and evapotranspiration rates, increased litterfall and leaf flushing during the Sunlight-rich dry season. Satellite data also indicated higher greenness level, a proven surrogate of photosynthetic carbon fixation, and leaf area during the dry season relative to the wet season. Some recent reports suggest that rainforests display no seasonal variations and the previous results were satellite measurement artefacts. Therefore, here we re-examine several years of data from three sensors on two satellites under a range of sun positions and satellite measurement geometries and document robust evidence for a seasonal cycle in structure and greenness of wet equatorial Amazonian rainforests. This seasonal cycle is concordant with independent observations of solar radiation. We attribute alternative conclusions to an incomplete study of the seasonal cycle, i.e. the dry season only, and to prognostications based on a biased radiative transfer model. Consequently, evidence of dry season greening in geometry corrected satellite data was ignored and the absence of evidence for seasonal variation in lidar data due to noisy and saturated signals was misinterpreted as evidence of the absence of changes during the dry season. Our results, grounded in the physics of radiative transfer, buttress previous reports of dry season increases in leaf flushing, litterfall, photosynthesis and evapotranspiration in well-hydrated Amazonian rainforests.
amazonian rainforests, article is available online, misr, modis, remote sensing, seasonality, supplementary material for this
1748-9326
1-6
Bi, Jian
438a2b3a-f984-4bad-9356-eba4330bab16
Knyazikhin, Yuri
84e2bfd7-e1bd-4f11-8167-9cabe2c060e3
Choi, Sungho
c63455ed-2e9d-41e5-866c-0fb0d4210414
Park, Taejin
6e3a4797-1c50-41d5-9132-507834d5a62c
Barichivich, Jonathan
7e85d6b2-1026-4799-a08b-7cfb1b27bf15
Ciais, Philippe
3cf3408c-b15a-46db-89b4-5388b0178da8
Fu, Rong
6e163993-51d8-499a-a7d4-224674d73f17
Ganguly, Sangram
36355354-d96b-42ec-87fe-a57bcd939479
Hall, Forrest
e82a6b04-95e1-4ace-bac7-aa285fe8bdaa
Hilker, Thomas
c7fb75b8-320d-49df-84ba-96c9ee523d40
Huete, Alfredo
f53fc154-f0ae-4689-b187-b110f8668adb
Jones, Matthew
7aaa98e2-a8e3-4eaf-9034-669c48cb893f
Kimball, John
fce1fe60-b2b1-4437-b2bd-43deeccb9df6
Lyapustin, Alexei I.
ee8fd005-4cb8-491c-a7c5-38d57a562608
Mõttus, Matti
02828cdb-933e-472a-a9bc-c459ae278e94
Nemani, Ramakrishna R.
8b7c61c8-7080-4919-a901-858b5e7e88f0
Piao, Shilong
804cbb77-9dc8-4ebc-8b00-b498a48be506
Poulter, Benjamin
97542307-dd41-434c-b9f6-bd1d1c0c0b8f
Saleska, Scott R.
bed29e2f-4f06-4d13-8e60-3b54ba2a8626
Saatchi, Sassan S.
d4d41345-632c-479e-ba48-ef82626a340c
Xu, Liang
a776b781-70a7-4e7d-bab3-62b7f7a49ca7
Zhou, Liming
ef94fa56-1f57-47cd-a174-b2b0a1aad535
Myneni, Ranga B.
f1c30bf7-c507-4693-b0a7-5d4277a0b7f7
Bi, Jian
438a2b3a-f984-4bad-9356-eba4330bab16
Knyazikhin, Yuri
84e2bfd7-e1bd-4f11-8167-9cabe2c060e3
Choi, Sungho
c63455ed-2e9d-41e5-866c-0fb0d4210414
Park, Taejin
6e3a4797-1c50-41d5-9132-507834d5a62c
Barichivich, Jonathan
7e85d6b2-1026-4799-a08b-7cfb1b27bf15
Ciais, Philippe
3cf3408c-b15a-46db-89b4-5388b0178da8
Fu, Rong
6e163993-51d8-499a-a7d4-224674d73f17
Ganguly, Sangram
36355354-d96b-42ec-87fe-a57bcd939479
Hall, Forrest
e82a6b04-95e1-4ace-bac7-aa285fe8bdaa
Hilker, Thomas
c7fb75b8-320d-49df-84ba-96c9ee523d40
Huete, Alfredo
f53fc154-f0ae-4689-b187-b110f8668adb
Jones, Matthew
7aaa98e2-a8e3-4eaf-9034-669c48cb893f
Kimball, John
fce1fe60-b2b1-4437-b2bd-43deeccb9df6
Lyapustin, Alexei I.
ee8fd005-4cb8-491c-a7c5-38d57a562608
Mõttus, Matti
02828cdb-933e-472a-a9bc-c459ae278e94
Nemani, Ramakrishna R.
8b7c61c8-7080-4919-a901-858b5e7e88f0
Piao, Shilong
804cbb77-9dc8-4ebc-8b00-b498a48be506
Poulter, Benjamin
97542307-dd41-434c-b9f6-bd1d1c0c0b8f
Saleska, Scott R.
bed29e2f-4f06-4d13-8e60-3b54ba2a8626
Saatchi, Sassan S.
d4d41345-632c-479e-ba48-ef82626a340c
Xu, Liang
a776b781-70a7-4e7d-bab3-62b7f7a49ca7
Zhou, Liming
ef94fa56-1f57-47cd-a174-b2b0a1aad535
Myneni, Ranga B.
f1c30bf7-c507-4693-b0a7-5d4277a0b7f7

Bi, Jian, Knyazikhin, Yuri, Choi, Sungho, Park, Taejin, Barichivich, Jonathan, Ciais, Philippe, Fu, Rong, Ganguly, Sangram, Hall, Forrest, Hilker, Thomas, Huete, Alfredo, Jones, Matthew, Kimball, John, Lyapustin, Alexei I., Mõttus, Matti, Nemani, Ramakrishna R., Piao, Shilong, Poulter, Benjamin, Saleska, Scott R., Saatchi, Sassan S., Xu, Liang, Zhou, Liming and Myneni, Ranga B. (2015) Sunlight mediated seasonality in canopy structure and photosynthetic activity of Amazonian rainforests. Environmental Research Letters, 10 (6), 1-6. (doi:10.1088/1748-9326/10/6/064014).

Record type: Article

Abstract

Resolving the debate surrounding the nature and controls of seasonal variation in the structure and metabolism of Amazonian rainforests is critical to understanding their response to climate change. In situ studies have observed higher photosynthetic and evapotranspiration rates, increased litterfall and leaf flushing during the Sunlight-rich dry season. Satellite data also indicated higher greenness level, a proven surrogate of photosynthetic carbon fixation, and leaf area during the dry season relative to the wet season. Some recent reports suggest that rainforests display no seasonal variations and the previous results were satellite measurement artefacts. Therefore, here we re-examine several years of data from three sensors on two satellites under a range of sun positions and satellite measurement geometries and document robust evidence for a seasonal cycle in structure and greenness of wet equatorial Amazonian rainforests. This seasonal cycle is concordant with independent observations of solar radiation. We attribute alternative conclusions to an incomplete study of the seasonal cycle, i.e. the dry season only, and to prognostications based on a biased radiative transfer model. Consequently, evidence of dry season greening in geometry corrected satellite data was ignored and the absence of evidence for seasonal variation in lidar data due to noisy and saturated signals was misinterpreted as evidence of the absence of changes during the dry season. Our results, grounded in the physics of radiative transfer, buttress previous reports of dry season increases in leaf flushing, litterfall, photosynthesis and evapotranspiration in well-hydrated Amazonian rainforests.

Full text not available from this repository.

More information

Accepted/In Press date: 1 June 2015
e-pub ahead of print date: 16 June 2015
Published date: 16 June 2015
Keywords: amazonian rainforests, article is available online, misr, modis, remote sensing, seasonality, supplementary material for this
Organisations: Geography & Environment

Identifiers

Local EPrints ID: 384674
URI: https://eprints.soton.ac.uk/id/eprint/384674
ISSN: 1748-9326
PURE UUID: 2654d0ab-f44e-4c00-bda0-6675b52673f6

Catalogue record

Date deposited: 13 Jan 2016 08:50
Last modified: 15 Jul 2019 20:55

Export record

Altmetrics

Contributors

Author: Jian Bi
Author: Yuri Knyazikhin
Author: Sungho Choi
Author: Taejin Park
Author: Jonathan Barichivich
Author: Philippe Ciais
Author: Rong Fu
Author: Sangram Ganguly
Author: Forrest Hall
Author: Thomas Hilker
Author: Alfredo Huete
Author: Matthew Jones
Author: John Kimball
Author: Alexei I. Lyapustin
Author: Matti Mõttus
Author: Ramakrishna R. Nemani
Author: Shilong Piao
Author: Benjamin Poulter
Author: Scott R. Saleska
Author: Sassan S. Saatchi
Author: Liang Xu
Author: Liming Zhou
Author: Ranga B. Myneni

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×