Drivers of carbon flux in drip irrigation maize fields in northwest China

Table 5 Partial correlation coefficients between environmental variables and net ecosystem exchange (NEE), ecosystem respiration (ER) and gross primary productivity (GPP)

Carbon flux	Year	Rn	Ta	VPD	SWC	IP	LAI
NEE	2014	− 0.47^a	− 0.320^a	0.153	− 0.303^a	− 0.176^b	− 0.817^a
	2015	− 0.390^a	− 0.470^a	0.044	− 0.148	− 0.146	− 0.806^a
	2016	− 0.625^a	− 0.666^a	− 0.407^a	− 0.266^a	− 0.175^b	− 0.497^a
	2017	− 0.581^a	− 0.638^a	− 0.449^a	− 0.148	− 0.109	− 0.749^a
	2018	− 0.480^a	− 0.666^a	− 0.11	− 0.293^a	− 0.188^b	− 0.765^a
ER	2014	0.448^a	0.395^a	− 0.037	0.231^a	− 0.013	0.775^a
	2015	0.258^a	0.733^a	0.350^a	0.339^a	0.034	0.742^a
	2016	0.313^a	0.675^a	0.217^a	0.111	0.05	0.471^a
	2017	0.329^a	0.770^a	0.432^a	0.272^a	0.114	0.878^a
	2018	0.338^a	0.618^a	− 0.202^b	0.384^a	0.154	0.929^a
GPP	2014	0.499^a	0.365^a	− 0.132	0.303^a	0.137	0.859^a
	2015	0.376^a	0.619^a	0.106	0.237^a	0.117	0.858^a
	2016	0.596^a	0.748^a	0.393^a	0.247^a	0.154	0.547^a
	2017	0.523^a	0.727^a	0.470^a	0.204^b	0.118	0.845^a
	2018	0.455^a	0.687^a	0.001	0.344^a	0.186^b	0.892^a

ER ecosystem respiration, NEE net ecosystem exchange, GPP gross primary productivity, Rn net radiation, Ta air temperature, VPD vapor pressure deficit, SWC soil water content, IP the sum of precipitation and irrigation, LAI leaf area index
^aSignificantly correlated at the 0.01 level (bilateral) and ^b significantly correlated at the 0.05 level (bilateral)

ISSN: 1750-0680