Projected Changes of Grassland Productivity along the Representative Concentration Pathways during 2010–2050 in China

Table 2

Analysis of impacts of influencing factors on NPP based on the econometric model.

Dependent variable: log (NPP)
	Model-I	Model-II	Model-III	Model-IV
log (ta)	0.035***	0.026***	−0.022***	−0.035***
	(−11.54)	(−8.12)	(−8.03)	(−9.72)
log (rain)	0.967***	0.856***	0.928***	0.963***
	(−197.32)	(−67.74)	(−83.42)	(−58.75)
log (sun)		−0.829***	−0.016	0.169
		(−9.48)	(−0.19)	−1.72
log (dem)			−1.745***	−1.803***
			(−67.42)	(−54.68)
Soil_n			−0.119***	0.036
			(−4.09)	(−1.03)
Soil_p			7.817***	6.550***
			(−19.8)	(−14.05)
Splain			0.026***	0.025***
			(−4.79)	(−3.54)
pop𝑡−1				0.031***
				(−3.59)
meat𝑡−1				0.156***
				(−12.73)
gdp1𝑡−1				−0.049***
				(−8.14)
Intercept	−2.127***	4.247***	12.42***	9.750***
	(−54.03)	(−6.31)	(−20.04)	(−13.06)
Adjusted 𝑅^2	0.732	0.733	0.818	0.838

 𝑡 statistics in parentheses: ^∗𝑃<0.05, ^∗∗𝑃<0.01, and ^∗∗∗𝑃<0.001.