Table 1.

Classification standard of each influencing factor in the collected results of the meta-analysis and its corresponding keyword classification in the bibliometric analysis

Groups	Influencing factor	Standard of classification	Corresponding keyword classification
Land use change (LUC)	Degradation	Ecosystem degradation, including diversity loss and loss of other ecological function	Degradation
	Restoration	The restoration of degraded or cultivated ecosystems, including vegetation recovery	Restoration
	Cultivation	Agricultural cultivation on other ecosystems	Cultivation
	Forestation	Forestation of other ecosystems, including plantation and agroforestry	Afforestation
	Agricultural abandonment	Changes from farmland to other ecosystems except forest, as farmland to forest was included in forestation	LUC
	Deforestation	Changes from forest to other ecosystems except farmland, as forest to farmland was included in cultivation	LUC
Management	N addition	Including N fertilization, N addition and N deposition	N management
	Chemical fertilizer	Other chemical fertilizer including N or without N	Chemical fertilizer
	Organic fertilizer	Organic fertilizer, organic manure, organic amendments and so on	Organic fertilizer
	Integrated fertilizer	Fertilization including both chemical fertilizer and organic fertilizer	Human activities
	Litter input	Including straw return, litter input and other organic matter inputs	Litter or straw
	No fertilizer	No fertilizer or organic matter input	Other factors
	Cover crop	Cover crop	Litter or straw
	Rotation	Cropping system including different crops or intercropping	Rotation
	No tillage	Including reduced tillage and zero tillage	Tillage
	Tillage	Including plow tillage, rotation tillage, deep tillage and others	Tillage
	Soil amendment	Soil amending with amendment inputs, including biochar, gypsum, lime, and others	Biochar, soil amendment
	Combined agricultural management	Management with at least 2 different agricultural measures, including organic farming and conservational farming	Agricultural management
	Reduced grazing	Including grazing exclusion and reduction	Grazing
	Grazing	Including different intensities and frequencies of grazing	Grazing
	Forest harvesting	Including whole tree harvest, stem harvesting, partial harvesting and different intensive harvesting	Forest management
	Other management	Film mulching, new rice varieties, inhibitors and so on	Agricultural management, pesticides
Environmental and climatic change	Warming	Including temperature increases, experimental warming and others	Warming
	Elevated CO2	Elevated CO2	Elevated CO2
	Rainfall increase	Rainfall increase	Rainfall
	Rainfall reduction	Rainfall reduction	Rainfall
	Wetting	Rewetting of drainage ecosystems or irrigation	Drainage or wetting
	Drying	Including the drainage of flooded areas and drought in uplands	Drainage or wetting
	Biotic disturbance	Soil disturbance by soil fauna, such as earthworms and so on	Biotic disturbance
	Plant invasion	Exotic plants invade the original ecosystem	Invasions
	Fire	Including wildfire and fire management	Fire
	Pollution	Including metal pollution, waste pollution, organic contamination, acid rain, and so on	Pollution
	Other environmental and climatic changes	Including increased snowpack, elevated UV-B, attenuated UV-B, elevated O3, freeze–thaw and so on	Climate change, environmental gradient

The categorization of keywords in the bibliometric analysis (29 influencing factors) and the influencing factors in the collected results of the meta-analysis (33 influencing factors) were not exactly the same because the information obtained via the two methods was different