Complex range shifts among forest functional types under the contemporary warming

Area of Science:

• Ecology
• Climate Change Biology
• Forest Science

Background:

• Species distribution shifts under climate change vary significantly among species and functional types (FTs).
• Understanding functional trait variation and species interactions is crucial for predicting ecosystem dynamics and climate change responses.
• Japanese tree species exhibit complex responses to temperature changes, influenced by life stage and functional traits.

Purpose of the Study:

• To analyze differences in juvenile and adult temperature ranges of Japanese tree species.
• To reveal how functional traits, such as seed mass, affect interactions between different FT groups (e.g., deciduous and evergreen broad-leaved trees).
• To understand the mechanisms driving nonparallel range shifts among FTs and their implications for ecosystem homogenization.

Main Methods:

• Analysis of juvenile and adult temperature ranges across distribution edges (mean, colder, warmer).
• Application of linear models and permutation tests to assess trait-environment relationships.
• Comparison of distribution range shifts between different FTs at ecotones.

Main Results:

• Juveniles generally preferred cooler sites, with variation explained by seed mass (lighter seeds colonized colder sites).
• Nonparallel range shifts were detected in three of eight ecotones, with contrasting shifts between FTs (e.g., deciduous vs. subalpine).
• Mechanisms like seed dispersal and competitive ability at different temperature edges drive FT-specific responses and potential homogenization.

Conclusions:

• Past warming has induced a general cold shift at the species level.
• Differential dispersal and competitive strategies among FTs lead to nonparallel range shifts, influencing ecosystem structure.
• These complex FT-level range shifts have significant implications for climate change mitigation and adaptation strategies in forest ecosystems.