Mowing and warming effects on grassland species richness and harvested biomass: meta-analyses

Climate and management affect grassland plant diversity but studies vary regarding the magnitude of changes in species richness. Here we develop a comprehensive understanding richness modification due to (mowing) climate (warming) variations worldwide, present results two meta-analyses from 999 1793 records (articles). Recorded articles had at least one experiment with case-control design. The show that both mowing (43 articles) warming (34 modify richness, which on average increased by c. 32% once-a-year (against no mowing) declined 13% ambient temperature). Our meta-analysis regime supports humped-back model, or cuts per year being level disturbance optimising We also observed warming-induced reduction is lower dry climates (< 300 mm yr-1) low elevations 1000 m a.s.l.). Where available, accounted for harvested biomass as concomitant variable found overall it decreased 21% 11% (warming). evidence provided an opposite response consistent competitive-exclusion hypothesis negatively correlated patterns between outcomes (high taxonomic production, vice versa). reported difficulties finding representative previous ones highlight need orient future research towards long-term experiments combined effects more robust inference environmental constraints performance.