3.3. Plant N and P concentration and its relationship with AGB of grasses
In native grasslands, SLD, MD, HD and ED grasslands decreased plant N concentration by average of 2.0%, 16.0%, 28.7% and 34.1%, respectively, as compared to the ND grassland (Fig. 4a). However, land degradation did not impact on P concentration (Fig. 4b). Compared to 5Ys grassland, plant N and P significantly decreased by 22.0% and 6.72%, 30.7% and 21.5%, 41.6% and 32.7%, and 47.5% and 45.7% in the 9Ys, 11Ys, 14Ys and 17Ys grasslands, respectively (Fig. 4).
# Insert Figure 4 #
There were significantly positive relationships between plant N and AGB (R2 =0.829, P <0.001), plant P and AGB (R2 =0.869, P <0.001) of grasses in active restoration grasslands, and between plant N and AGB (R2 =0.809,P <0.001) in native grasslands (Fig. 5a). However, there were insignificant correlations between AGB and plant P in native grasslands (R2 =0.105, P =0.224) (Fig. 5b). Plant N and P of grasses in active restoration grasslands shows stronger association with its AGB than native grasslands.
# Insert Figure 5 #