Impact of mowing frequency and temperature on the production of temperate grasslands: explanations received by an individual-based model

Abstract

Grasslands represent an important ecosystem type as they provide numerous ecosystem services. Field studies have shown that temperate grasslands with high diversity can be highly productive. Management and changing environmental conditions can impact the diversity–production relationship. However, the specific mechanisms and role of biodiversity, environmental factors or anthropogenic interventions that lead to changes in production are not well understood. Here, we used the individual-based grassland model GRASSMIND parameterized for a field biodiversity experiment to analyze changes in the diversity–production relationship when varying the mowing frequency and increasing air temperature. Our results revealed that the positive diversity–production relationship persists with varied mowing frequency and temperature increase, with an increased proportion of herbs in more frequently mown grasslands (from 78% to 85%). Using the model, we further investigated quantitatively how different processes (e.g. plant shading) affect grassland dynamics and production under varied mowing frequencies and air temperature. Although aboveground net primary production (ANPP) decreased in more frequently mown grasslands (20% less ANPP), biomass yields increased due to an even stronger decrease in space-dependent plant mortality (30% less crowding). Plant mortality (intrinsic and by crowding) caused more biomass losses than caused by shading between plants or by a reduced production due to temperature increase. This study revealed how models, complementary to field experiments, can be used to analyze and quantify the importance of mechanisms and the role of environmental factors in grassland dynamics.