Supplementary Data

Increasing global vegetation browning hidden in overall vegetation

greening: Insights from time-varying trends

Naiqing Pan1,2,3, Xiaoming Feng1,4*, Bojie Fu1,4, Shuai Wang1,4, Fei Ji5,6, Shufen Pan3

1. State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-

Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;

2. University of Chinese Academy of Sciences, Beijing 100049, China;

3. International Center for Climate and Global Change Research, School of Forestry and

Wildlife Sciences, Auburn University, Auburn 36832, USA;

4. Joint Centre for Global Change Studies, Beijing 100875, China;

5. College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China;

6. Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College

of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China.

Correspondence to: Xiaoming Feng (fengxm@rcees.ac.cn)

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Fig. S1 Example of EEMD decomposition of a NDVI time series. (a) shows the raw data at

53.25˚N, 29.25˚E, and (b)-(e) show IMF 1-3 and the secular trend, respectively. The blue line

(including the bold segment) represents the accumulated trend variation at t from 1982, and the

bold blue segment represents the instantaneous rate of the trend at t.

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Fig. S2(a) Variations in EEMD trends of 10000 randomly generated white noise series and their

frequency distributions in 1990(b), 2000(c), and 2010(d). Here, variations in EEMD trends at t are

defined as the difference between Trend(t) and Trend(2013). The two bold white lines in (a)

indicate the 1.96-standard-deviation spread.

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Fig.S3 Significance test results of EEMD trends during 1982-2013 (a) and linear trends during

1982-2013 by two-tailed t-test (b) and Mann-Kendall test (c). (d)-(f) and (g)-(i) show the

significance test results of NDVI trends from EEMD, Model 1, and Model 2 before and after the

turning point (breakpoint), respectively. (j)-(l) show the significance of the identified trend shifts

from EEMD, Model 1, and Model 2, respectively. The insets show the frequency distributions of

the corresponding classes.

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Fig. S4 EEMD trends in growing season NDVI during 1982-2013. To facilitate direct comparisons

with the results of linear regression (Fig. 3a), Trend(2013) (defined in the main text) was divided

by the time span. The inset shows the frequency distribution of the corresponding values.

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Fig. S5Frequencies of the four types of trends in different land cover classes. ‘a’, ‘b’ and ‘c’

correspond to the results of EEMD, PLM 1 and PLM 2, respectively.

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Fig. S6 Spatial distribution of the abrupt change at breakpoint. The inset shows the frequency

distribution of the corresponding values.

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Fig. S7 Temporal changes in the area of significant browning trends.

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Fig. S8 Significance levels of the trends of MODIS Terra-C5 NDVI (a) and MODIS Terra-C6

NDVI (b) during the period 2001-2013.

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Fig. S9 Global mean NDVI and its trends detected by PLM2. (a) and (b) show the results of

GIMMS3gV1 and GIMMS3gV0, respectively.

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Table S1: Overall trends, turning points (breakpoints) and piecewise variations in trend values

revealed by Models 1-3 and EEMD. ‘Overall trend’ is the accumulated variation in the trend value

during 1982-2013, and itequals Trend(2013) and 31×β0 (see Methods) in EEMD and Model 3,

respectively. For EEMD, trend variations before and after the turning point are Trend(TP) and

Trend(2013)-Trend(TP),respectively; for Models 1 and 2, trend variation in each segment equals

the slope multiplied by the time span. ‘TP’ and ‘BP’ are abbreviations for turning point and

breakpoint, respectively. In this table, accumulated trend variations were multiplied by 1000 for a

clearer presentation. ‘Null’ indicates a monotonic EEMD trend. ‘*’ indicates a trend or turning

point (breakpoint)significant at P<0.05.

Overall trend EEMD Model 1 Model 2

Land

cover Linear

regression

EEMD TP

Before

TP

After

TP TP

Before

TP

After

TP BP

Before

BP

After

BP

Abrupt

change

ENF 7.12 2.85 2004 7.91 -5.06 1989* 21.81* -5.63 1991* 27.63* -1.77 -10.05*

EBF 19.49* -6.07 2001 6.38 -12.45 2008* 27.51* -22.27* 1994 -9.36 -11.48 28.12

DNF 31.15* 55.23* Null Null Null 2006 15.76 22.18 2002 28.09* 47.04* -28.21

DBF -5.79 -10.40 Null Null Null 1997* 8.52 -13.98 1994 -7.69 -21.58 16.83

MF 36.21* 34.80* Null Null Null 1989* 31.37* 15.24 1991 45.45* 15.33 -12.53

OS 22.04* 24.15* Null Null Null 2008 15.60* 10.11 2009 13.33* -22.08 22.70

WSA 14.72* 12.42 Null Null Null 1986* 14.51 8.05 1990 26.69* 11.64 -13.80

SAV 13.36* 7.49 2006 10.56 -3.06 2009 16.48* -11.07 1994 -4.03 -5.47 15.83

GRA 17.76* 29.16* Null Null Null 1990* 17.04* 5.65 1998* 23.90* 5.56 -8.49*

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PW 20.08* 17.92 2003 20.23 -2.31 1997* 28.79* -8.15 1994* 27.62 -12.78 8.64*

CRO 32.61* 31.29* Null Null Null 1990* 31.70* 10.12* 1998* 42.75* 9.61* -13.43*

CNV 30.55* 21.78 2009 22.47

*

-0.69 1989* 24.48* 13.95* 1994* 14.60 2.44 10.96*

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