Contrasting demographic processes underlie uphill shifts in a desert ecosystem

Area of Science:

• Ecology
• Climate Change Biology
• Botany

Background:

• Climate change is driving extensive plant range shifts globally.
• Most studies focus on distribution changes, not the demographic processes behind them.
• Understanding these demographic underpinnings is crucial for predicting future plant community composition.

Purpose of the Study:

• To investigate elevational range shifts in desert plant species.
• To identify the demographic processes (recruitment, survival) driving these shifts.
• To assess the impact of life-history rates on the magnitude of range shifts.

Main Methods:

• Utilized rephotography to compare historical (1978-1982) and modern (2015-2016) photographs.
• Analyzed demographic outcomes for 4263 individuals across 11 perennial species.
• Studied a 1000-m elevational gradient in the Colorado Desert, Southern California.

Main Results:

• All 11 species exhibited an average upward elevational shift of 45 meters.
• Species showed varied demographic responses, with some having higher recruitment and others higher survival at higher elevations.
• Faster life-history rates correlated with larger elevational range shifts.

Conclusions:

• Demographic processes and life-history traits are key drivers of plant range shifts.
• Desert ecosystems are sensitive to climate change, even with slow-moving perennial plant dynamics.
• Elevational shifts in plant species highlight the ongoing impacts of rising temperatures and drought.