Table 2. Significance of Pearson's rank correlations between CH₄ emission and environmental factors.

	CH4 emission rates
	2005	2006	2007	E.valleculosa	C.muliensis	K.tibetica
Surfacetemperature	**	ns	ns	*	ns	ns
5 cm soiltemperature	ns	ns	*	*	ns	**
10 cm soiltemperature	ns	ns	**	*	ns	*
5 cm soil Eh	**	ns	ns	ns	ns	nd
10 cm soil Eh	**	*	ns	ns	ns	nd
15 cm soil Eh	**	*	ns	ns	ns	nd
The Standingwater depth	**	**	ns	ns	**	nd

ns indicates the correlation is not significant.

^*indicates the correlation is significant (P<0.05);

^**indicates the correlation is highly significant (P<0.01); nd means no data.