Table 2 Variable definitions in this study.

From: Prediction of aboveground grassland biomass on the Loess Plateau, China, using a random forest algorithm

Factors

Definition

Description

Elev

Digital Elevation Model (DEM) on the Loess Plateau

Elevation (m)

Slope

Slope calculated by DEM on the Loess Plateau

Slope

TNDVI

NDVI calculated by TM data

Normalized difference vegetation index (NDVI)

L2011/L2012/L2013

Average LAI of 2011/2012/2013 summer

Leaf area index (LAI)

F2011/F2012/F2013

Average FPAR in 2011/2013/2013 summer

Fraction of Photosynthetically Active Radiation (FPAR)

FM

(F2011 + F2012 + F2013)/3

R2011/R2012/R2013

Average rainfall of 2011, 2012,2013

Rainfall (mm)

RM

(R2011 + R2012 + R2013)/3

SR2011/SR2012/SR2013

Average rainfall in 2011/2012/2013 summer

SRM

(SR2011 + SR2012 + SR2013)/3

HT2011HT2012/HT2013

Average of the high temperature in 2011,2012,2013

Temperature(°C)

HTM

(HT2011 + HT2012 + HT2013)/3

LM

(L2011 + L2012 + L2013)/3

LT2011/LT2012/LT2013

Average of the low temperature in 2011/2012/2013

LTM

(LT2011 + LT2012 + LT2013)/3

ST2011/ST2012/ST2013

Average temperature in 2011, 2012,2013 summer

ST

(ST2011 + ST2012 + ST2013)/3

T2011/T2012/T2013

Average temperature in 2011, 2012, 2013

TM

(T2011 + T2012 + T2013)/3

x

Longitude

Geographic location (°)

y

Latitude