DIVERSITY-PRODUCTIVITY TRADE-OFF DURING CONVERTING CROPLAND TO PERENNIAL GRASSLAND IN THE SEMI-ARID AREAS OF CHINA

The trade-off between plant community structure and function is an important issue during grassland restoration. It is essential to assess changes of structure and function after converting farmland to grassland. Three restoration stages (5, 15, and 30 years) were studied to determine the optimum time when the trade-off between diversity and productivity occurs. The results showed that the vegetation coverage, height, and productivity significantly increased, but the species richness, diversity, and density significantly decreased along the restoration time. Grassland community presented a succession from small individuals and high density to larger individuals and lower density. The community changed from being dominated by grass and forb functional groups to being dominated only by the grass functional group. The dominant grass functional group plays a decisive role on community structure and function (productivity, diversity, and density) during grassland succession. Our results suggest that community structure and function were mainly driven by the dominant grass functional group during the long-term succession. Grassland should be utilized to suppress the leading role of the dominant functional groups in the 20th year for keeping the trade-off of diversity and productivity. We suggest that the restoration grassland should be considered to use appropriately in the 20th year. Our study could provide a key guidance for maintaining the community structure and function trade-off for cropland-converted grassland management in the semi-arid areas. Copyright (C) 2016 John Wiley & Sons, Ltd.