Evidence of shift in C₄ species range in central Argentina during the late Holocene

Aim

Millennial-scale biogeographic changes are well understood in many parts of the world, but little is known about long-term vegetation dynamics in subtropical regions. Here we investigate shifts in C₃/C₄ plant abundance occurred in central Argentina during the past few millennia

Methods

We determined present day soil organic matter δ¹³C signatures of grasslands, shrublands and woodlands, containing different mixtures of C₃ and C₄ plants. We measured past changes in the relative cover of C₃/C₄ plants by comparing δ¹³C values in soil profiles with present day δ¹³C signatures. We analyzed ¹⁴C activity in soil depths that showed major changes in vegetation.

Results

Present day relative cover of C₃/C₄ plants determines whole ecosystem δ¹³C signatures integrated as litter and superficial soil organic matter (R² = 0.78; p