Data from: Will trees or grasses profit from changing rainfall regimes in savannas?

• Increasing rainfall variability is widely expected under future climate
change scenar- ios. How will savanna trees and grasses be affected by
growing season dry spells and altered seasonality and how tightly coupled
are tree-grass phenologies with rainfall? • We measured tree and grass
responses to growing season dry spells and dry season rainfall. We also
tested if the phenologies of 17 deciduous woody species and the Soil
Adjusted Vegetation Index of grasses were related to rainfall between 2019
and 2023. • Tree and grass growth was significantly reduced during growing
season dry spells. Tree growth was strongly related to growing season soil
water potentials and limited to the wet season. Grasses can rapidly
recover after growing season dry spells and grass evapotranspiration was
significantly related to soil water potentials in both the wet and dry
seasons. Tree leaf flushing commenced before the rainfall onset date
with little subsequent leaf flushing. Grasses grew when moisture
became available regardless of season. • Our findings suggest that
increased dry spell length and frequency in the growing season may slow
down tree growth in some savannas, which together with longer growing
seasons may allow grasses an advantage over C3 plants that are advantaged
by rising CO2 levels.