Climate Change Projected Effects on Hamatocaulis vernicosus Occurrence in Romania.

Area of Science:

• Ecology
• Conservation Biology
• Bryology

Background:

• Hamatocaulis vernicosus is a European moss of conservation concern, listed under the EU Habitats Directive and vulnerable in Romania.
• Despite its protected status, the species is under-recorded in Romania, with many suitable peatland habitats yet to be surveyed.
• Transition mire and quaking bog ecosystems (NATURA 2000 code: 7140) support H. vernicosus, characterized by wet, oligo- to mesotrophic conditions (pH 5.0-7.5).

Purpose of the Study:

• To assess the current distribution of Hamatocaulis vernicosus in Romania.
• To model suitable habitats for H. vernicosus under future climate change scenarios.
• To provide insights for targeted conservation planning of H. vernicosus and its associated peatland ecosystems.

Main Methods:

• Field surveys confirmed 15 locations (10 existing, 5 new) of H. vernicosus across Romania's Continental and Alpine bioregions.
• Species distribution modeling (SDM) using ensemble models predicted suitable habitats.
• Climate change projections (SSP245, SSP585) were used to forecast range shifts and fragmentation.

Main Results:

• H. vernicosus distribution is primarily influenced by mean annual temperature and temperature range, favoring cold, stable climates with high rainfall.
• SDM showed good predictive performance (AUC 0.79-0.83; TSS 0.54-0.59).
• Climate models predict substantial range losses for H. vernicosus: ~30% by 2050 and ~40-60% by 2100, with increased fragmentation, particularly between the Eastern and Southern Carpathians.

Conclusions:

• Current increases in recorded localities reflect enhanced survey efforts, not an improved conservation status.
• Climate change poses a severe threat to H. vernicosus, projecting significant range contractions and habitat fragmentation.
• Integrating field data with predictive modeling is crucial for effective conservation strategies for H. vernicosus and its vital peatland habitats.