Relationships between net primary production and plant diversity under climate change

Net primary production ( NPP ) is an ecosystem function that commonly increases with plant diversity due to complementary use of resources by species with different ecological niches. However, higher temperature and lower rainfall – two major components of climate change – can modify the performance of plant species and alter these positive relationships. This study proposes to test the effect of climate change on the relationship between NPP and species richness. Seeds of 11 herbaceous species native to the Chihuahuan Desert were used to randomly assemble plant communities with different species richness levels. These communities were developed under both the current climate and simulated climate change conditions in an abandoned field during the rainy season. Open‐top chambers were used to increase temperature, while rainout shelters were used to reduce rainfall. The induction of climate change conditions reduced soil moisture, decreased plant biomass production, and caused species losses. Higher temperature and lower rainfall also altered interspecific interactions, as some species shifted their relationships with others from competition to neutrality or facilitation. Although NPP increased linearly with plant richness in both climate treatments, these relationships were weaker under climate change conditions than under the current climate. These results suggest that niche complementarity is the main mechanism that currently regulates NPP , and it seems that it will continue to regulate this ecosystem function in the future. However, climate change will reduce NPP in herbaceous plant communities of the Chihuahuan Desert and decrease its dependence on plant diversity.