Plowing, seeding, and fertilizing differentially influence species diversity, functional groups and community productivity in a degraded steppe

Abstract

The restoration of degraded grasslands can be achieved via multiple methods (e.g., increasing plant propagule input, improving site conditions, and enhancing soil resources); however, little is known about the relative roles of these methods. We conducted an experiment in Inner Mongolia (China) to address how plowing, seeding, and fertilizing influenced species diversity, functional groups, and community productivity in a degraded steppe. Plowing decreased plant species richness by disproportionally enhancing species loss and gain, had no effect on the relative abundance of grasses, legume forbs, and non-legume forbs, and marginally decreased the community biomass. Seeding legumes decreased plant species richness by disproportionally enhancing species loss and gain; seeding legumes or both grasses and legumes significantly affected the relative abundance of grasses, legume forbs, and non-legume forbs. Unexpectedly, seeding decreased aboveground plant community biomass, which might be linked to a nonproportional decrease in per capita biomass. Fertilization did not influence plant species richness, loss, gain, or turnover; however, fertilization increased the relative abundance of grasses and decreased that of legumes and enhanced community biomass. There were significant interactions among plowing, seeding and fertilizing, but these interactions were not synergistic. Over 70% of lost or gained species were perennial plants, implying that perennials might be more susceptible to these treatments than annuals/biennials. These findings suggest that these three restoration practices might have differential effects on plant species diversity, plant functional groups, and plant community productivity in Inner Mongolia and that their combined effects might not be positive for degraded steppes.