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Title: Soil Carbon Loss and Weak Fire Feedbacks During Pliocene C 4 Grassland Expansion in Australia
Abstract

C4grasslands proliferated later in Australia than they did on other continents (∼3.5 Ma vs. 10–5 Ma). It remains unclear whether this delay reflects differences in climate conditions or ecological feedbacks, such as fire, that promote C4ecosystems. Here, we evaluated these factors using terrestrial biomarkers from marine sediments off western Australia. Fire‐derived polycyclic aromatic hydrocarbons (PAH) indicate fire ecology did not substantially change during or following C4expansion. The presence of fire‐adapted C3woody vegetation likely diminished the role of fire and delayed C4expansion until it was prompted by climate drying between 3.5 and 3.0 Ma. At the same time, mass accumulation rates of weathered PAHs increased 100‐fold, which indicates a significant loss of soil carbon accompanied this ecosystem shift. The tight couplings between hydroclimate and carbon storage altered boundary conditions for Australian ecosystems, and similar abrupt behavior may shape environmental responses to climate change.

 
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NSF-PAR ID:
10373192
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Geophysical Research Letters
Volume:
48
Issue:
2
ISSN:
0094-8276
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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