Abstract
Ecosystems may exist in alternative stable states and thereby extremely
differ in ecosystem structure and functions, including gross primary
productivity (GPP), which is crucial for assessing an ecosystem’s
ability to capture atmospheric carbon dioxide, especially under the
context of climate change. This study applied alternative stable states
theory to evaluate GPP in global dryland forests, and analyzed
multi-year average GPP data alongside environmental factors such as the
Aridity Index and mean annual precipitation. Here, we found the
existence of alternative stable states of GPP along the aridity
gradient. Mean GPP were 893.12 gC/m²/year and 1539.86 gC/m²/year under
lower and higher branches of alternative stable states, respectively,
compared to the current mean value of 1203.02 gC/m²/year. Notably, we
observed striking regional disparities in GPP, with Africa and Oceania
predominantly in the higher alternative stable state, while North
America and Asia were in the lower alternative stable state. However,
GPP along mean annual precipitation did not exhibit alternative stable
states, but a significant variation during the medium range of mean
annual precipitation (241-402 mm year-1). The relationships between GPP
data and environmental factors were consistent across different forest
types. This study sheds light on dryland forest productivity and
indicates adaptive management strategies that should be used to bolster
ecosystem function in the context of climate change.