Consistent population declines but idiosyncratic range shifts in Alpine orchids under global change

Area of Science:

• Ecology
• Botany
• Conservation Biology

Background:

• Mountains are critical biodiversity hotspots.
• These ecosystems are highly vulnerable to environmental changes.
• Orchids are key indicators of mountain ecosystem health.

Purpose of the Study:

• To quantify population changes and range-shift dynamics of European Alps orchids over three decades.
• To identify factors influencing local extinctions and population declines.
• To assess orchid species' responses to climate warming and habitat alteration.

Main Methods:

• Analysis of population changes along elevational gradients.
• Tracking range-shift dynamics over 30 years for numerous orchid species.
• Investigating correlations between population trends and environmental factors like habitat alteration and climate.

Main Results:

• Local extinctions were more frequent in small populations and at the rear edge of species' ranges.
• Population density decreased for most species, particularly at rear edges, indicating multiple pressures.
• Over 50% of orchid species showed delayed range shifts, lagging behind climate warming.

Conclusions:

• Orchid populations in the European Alps are significantly impacted by global change.
• Vulnerability is linked to population size, habitat alteration, and rear-edge distribution.
• Long-term, high-resolution monitoring is crucial for understanding and mitigating global change effects on mountain flora.