Remote Sens. 2013, 5(3), 1484-1497; doi:10.3390/rs5031484
Article

Global Latitudinal-Asymmetric Vegetation Growth Trends and Their Driving Mechanisms: 1982–2009

1 Environmental Sciences Division, Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 2 Climate Change Science Institute/Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 3 Department of Earth and Environment, Boston University, 675 Commonwealth Avenue, Boston, MA 02215, USA
* Author to whom correspondence should be addressed.
Received: 1 February 2013; in revised form: 13 March 2013 / Accepted: 18 March 2013 / Published: 21 March 2013
(This article belongs to the Special Issue Monitoring Global Vegetation with AVHRR NDVI3g Data (1981-2011))
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Abstract: Using a recent Leaf Area Index (LAI) dataset and the Community Land Model version 4 (CLM4), we investigated percent changes and controlling factors of global vegetation growth for the period 1982 to 2009. Over that 28-year period, both the remote-sensing estimate and model simulation show a significant increasing trend in annual vegetation growth. Latitudinal asymmetry appeared in both products, with small increases in the Southern Hemisphere (SH) and larger increases at high latitudes in the Northern Hemisphere (NH). The south-to-north asymmetric land surface warming was assessed to be the principal driver of this latitudinal asymmetry of LAI trend. Heterogeneous precipitation functioned to decrease this latitudinal LAI gradient, and considerably regulated the local LAI change. A series of factorial experiments were specially-designed to isolate and quantify contributions to LAI trend from different external forcings such as climate variation, CO2, nitrogen deposition and land use and land cover change. The climate-only simulation confirms that climate change, particularly the asymmetry of land temperature variation, can explain the latitudinal pattern of LAI change. CO2 fertilization during the last three decades was simulated to be the dominant cause for the enhanced vegetation growth. Our study, though limited by observational and modeling uncertainties, adds further insight into vegetation growth trends and environmental correlations. These validation exercises also provide new quantitative and objective metrics for evaluation of land ecosystem process models at multiple spatio-temporal scales.
Keywords: global vegetation growth trend; LAI; CLM4; factorial simulation; evaluation; detection and attribution study

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MDPI and ACS Style

Mao, J.; Shi, X.; Thornton, P.E.; Hoffman, F.M.; Zhu, Z.; Myneni, R.B. Global Latitudinal-Asymmetric Vegetation Growth Trends and Their Driving Mechanisms: 1982–2009. Remote Sens. 2013, 5, 1484-1497.

AMA Style

Mao J, Shi X, Thornton PE, Hoffman FM, Zhu Z, Myneni RB. Global Latitudinal-Asymmetric Vegetation Growth Trends and Their Driving Mechanisms: 1982–2009. Remote Sensing. 2013; 5(3):1484-1497.

Chicago/Turabian Style

Mao, Jiafu; Shi, Xiaoying; Thornton, Peter E.; Hoffman, Forrest M.; Zhu, Zaichun; Myneni, Ranga B. 2013. "Global Latitudinal-Asymmetric Vegetation Growth Trends and Their Driving Mechanisms: 1982–2009." Remote Sens. 5, no. 3: 1484-1497.

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