Data from: Vegetation type controls root turnover in global grasslands

Abstract: Aim: Root turnover is an important process determining carbon
and nutrient cycling in terrestrial ecosystems. It is an established fact
that root turnover is jointly regulated by climatic, edaphic, and biotic
factors. However, the relative importance of these forces in determining
the global patterns of root turnover time is far from clear. Location:
Global. Time period: 1946–2017. Major taxa studied: Grasslands. Methods:
We compiled a database of 141 sites with 433 observations on root turnover
time and applied structural equation modelling (SEM) to investigate the
relative contribution of climate, soil properties, and vegetation type to
the observed variations in root turnover time. Results: Root turnover time
was 3.1 years on average across the global grasslands and differed
significantly among grassland types (tropical grassland & savanna,
temperate grassland & meadow, alpine grassland & meadow,
tundra, and desert). It decreased with mean annual temperature, mean
annual precipitation, and Palmer Drought Severity Index but increased with
soil organic carbon content, total nitrogen content, and carbon: nitrogen
ratio. Soil bulk density and soil texture also significantly affected root
turnover time, with clay content negatively correlating to root turnover
time and explaining more variations than bulk density and sand content.
The SEM showed that climatic factors had dominant effects on root turnover
time when vegetation type was not considered. Vegetation type became the
primary driver when it was included in the SEM. Main conclusions: Our
results highlight that the influences of climatic and edaphic factors on
root turnover time are predominantly manifested through vegetation type.
The critical role of precipitation as revealed for the first time in this
study challenges our current understanding of climate impacts on root
turnover time. The findings necessitate accurate representation of
vegetation type in Earth system models to predict root function dynamics
under global change.