Assessing climate-driven treeline dynamics via the habitat suitability index

Area of Science:

• Ecology
• Climate Change Biology
• Forest Science

Background:

• Alpine treelines are sensitive indicators of climate change impacts on forest ecosystems.
• Predicting long-term treeline dynamics under future climate scenarios is crucial but challenging.

Purpose of the Study:

• To forecast the spatiotemporal shifts of the Larix chinensis treeline ecotone in the Taibai Mountains under future climate conditions.
• To identify key climatic factors influencing treeline dynamics and understand aspect-dependent shifts.

Main Methods:

• An ensemble species distribution modeling framework was developed, integrating Generalized Linear Model, Random Forest, Maximum Entropy Model, and eXtreme Gradient Boosting.
• The habitat suitability index (HSI) was used to forecast spatiotemporal shifts.
• Growing-season temperature and elevation were analyzed as primary limiting factors.

Main Results:

• The ensemble model accurately reproduced current distribution patterns of Larix chinensis.
• Suitable habitats are projected to expand by 3.97-16.19% by the 2100s under various climate scenarios.
• Treeline shifts exhibited a pronounced aspect-dependent pattern, with stable increases concentrated on southern slopes and decreases on northern slopes.

Conclusions:

• Growing-season temperature is the primary driver of treeline establishment and migration, with elevation reflecting a 'temperature signal'.
• Future treeline expansion is anticipated, with a notable increase dominating across scenarios.
• Findings provide critical insights for adaptive management strategies in high-altitude mountain forest ecosystems.