Interannual variability in plant below-ground bio- mass in a mountain grassland a ected by manipulated rainfall

Field experiment was established to quantify the e ects of di erent amounts of rainfall on dry mass of below-ground plant parts in mountain grassland. Roofs constructed above the canopy of grass stands and gravity irrigation simulate three climate scenarios: (1) rainfall reduced by 50% (dry), (2) rainfall enhanced by 50% (wet) and (3) the full natural rainfall of the current growing season (ambient). Re- sults of the four-year experiment suggest that dry mass of below-ground plant parts was a ected signi cantly by treatments and time. A lower amount of pre- cipitation resulted in a decrease of the dry mass of below-ground plant parts. A de- creasing tendency in the amount of below-ground plant matter was recorded af- ter reduction of precipitation during four years. The greatest di erences between treatments (statistically signi cant) were found in the third year (2008) when 1571 and only 1 172 g.m 2 of total below-ground dry mass was respectively accumulated in wet and dry treatments. Thus our results indicate that the reduced amount of rainfall can result in the lower accumulation of below-ground plant biomass in some mountain meadows.