Phosphorus effects on global grassland productivity and plant diversity: A meta-analysis

Phosphorus (P) addition can affect ecosystem functions. It plays an important role in the productivity and nutrient cycling of grassland ecosystems. However, the effects of P addition on plant community diversity and productivity remain controversial. We analyzed data from 139 studies to assess the effects of P addition on grassland ecosystems. Our meta-analysis examined how different P addition amounts, grassland types, and P addition durations influence plant communities. P addition increased Aboveground Net Primary Productivity (ANPP) by 13.15 % (P < 0.05) and reduced species richness by 6.47 %. As P addition increased, the ANPP enhancement rose from 6.52 % to 19.23 %, while the negative effect on species richness intensified from −6.42 % to −11.10 %. P addition had a positive effect the ANPP of on arid grassland, which increased 15.96 %. With longer P addition duration, the ANPP increase declined from 12.95 % to 8.11 %, and the reduction in species richness deepened from −6.73 % to −9.76 %. There was a significant negative correlation between ANPP and P addition, but there was no significant correlation between community diversity and P addition. There is a large correlation between species richness and ANPP. This study found that P addition changed community assembly by changing the community allocation mechanism and breaking the resource constraints. Community productivity and diversity were affected by changing the distribution of functional traits and the redistribution mechanism of nutrient resources of dominant species in the community.