3.4 Ecosystem multifunctionality
Nitrogen
addition significantly affected the EMF of L. chinensis grassland
in saline-sodic soil (Fig.7). The analysis of one way ANOVA showed that
there were significant differences on the EMF of L. chinensisgrassland under different N addition rates (F=35.33,P <0.001, Fig.7A). The EMF was negative when N addition
rates were from 0 to 60 kg ha-1, and the EMF was
positive while N addition rates were from 90 to 210 kg
ha-1. This demonstrated that the EMF of L.
chinensis grassland increased with N addition rates increasing in
saline-sodic soil, but the EMF didn’t increase when N addition rates
reached enough levels (from 120 to 210 kg ha-1in the
study). It was found that the relationship between the EMF and N
addition level was quadratic curve model (R2=0.88116,P <0.0001, Fig.7B). In the study, the EMF was the
maximum when N addition rates were 150 or 180 kg ha-1,
while the EMF would decrease if N addition rate reached at 210 kg
ha-1. Therefore, the EMF of L. chinensisgrassland was affected by N addition rates to a large extent in
saline-sodic soil of Northeast China.