Warming and nitrogen addition alter flowering phenology and plant
community composition in a desert steppe
Abstract
The strong control of temperature on the timing of plant phenology is
expected to cause substantial shifts in flowering times under climate
change. Yet, the sensitivity of flowering phenology in dryland regions
to climate change, and the potential implications for community
composition, remain largely unexplored. Here, we investigate the effects
of climate warming and nitrogen addition on flowering phenology of four
C3 plants and two C4 plants and explore cascading effects on shifts in
C3 vs C4 plant dominance in a 17-year field experiment in a desert
steppe. Across the last 10 years of the experiment (2013–2022), we
found that warming had a greater effect on phenological shifts in C3
than in C4 plants. Warming significantly advanced the flowering time of
C3 plants by 4.3 ± 0.1 days and of C4 plants by 2.8 ± 0.1 days. Warming
also reduced the duration of flowering by 1.8 ± 0.1 days and decreased
the dominance of C3 plants compared to C4 plants (P<0.05). Nitrogen
addition extended the duration of flowering of C4 plants by 3.4 ± 0.2
days and increased their relative dominance, while having no effect on
C3 plants. Structural equation models highlighted that these
phenological responses were influenced by soil temperature and soil
water availability. Our results show the divergent phenological
responses between C3 and C4 plants under global changes, predicting
shifts in dominance between these plant types in temperate dryland
ecosystems.