Morphological and physiological traits of dominant plant species in response to mowing in a temperate steppe.

Abstract

Mowing is a common grassland management to feed livestock during winter by harvesting hay in autumn in many high latitude regions. Trait-based approach has been used to explain the responses of plant community to disturbance resulting from environmental changes and human activities. However, few studies have focused on the mechanisms underlying responses of grassland ecosystem to mowing from perspective of plant traits. Here, we investigated the effects of mowing on plant community of a temperate steppe in Inner Mongolia of northern China by field experiments to dissect the trade-off between morphological and physiological traits in response to short-term (4 years) and long-term (16 years) mowing. Specifically, we evaluated the two strategies associated with nutrient acquisition of two dominant species in response to mowing by measuring leaf and root morphological traits and physiological traits of root carboxylate exudation, AMF colonization and soil microbial community. We found that long-term mowing, but not short-term mowing, led to an increase in species richness. In addition, mowing decreased overall plant biomass of grassland community, but enhanced and suppressed growth of forbs and grasses, respectively. However, the ratio of forbs to grasses in the community was dependent on mowing duration, such that the forbs became more dominant than the grasses under long-term mowing. Our results revealed that short-term mowing reduced soil microbial biodiversity and root colonization of AMF in the grass Stipa krylovii, while root AMF colonization and carboxylate exudation in the forb Artemisia frigida were enhanced by short-term mowing. In long-term mowing, the functional traits associated with leaf resource conservation (i.e. leaf tissue density) and root resource acquisition were reduced in the grass, while the functional traits related to leaf resource acquisition and root resource conservation were increased in the forb, highlighting the species-specific and divergence in leaf and root traits in the grass and forb of temperate steppe in response to mowing. These novel findings demonstrate that physiological and morphological strategies are main drivers for dominant species in response to mowing in temperate grasslands.