Plasticity response of desert shrubs to intense drought events at different phenophases under the context of climate change

Global climate change has led to the frequent occurrence of intense drought events in mid-latitude desert ecosystems, coupled with uneven rainfall distribution across phenophases within the year. However, the impact of intense drought events at different phenophases on plant growth and drought resistance strategies still lacks clear conclusions. We selected the typical desert semi-shrubs Artemisia ordosica as our research object, and constructed a rain shelter to simulate intense drought events (without rainfall for 30 consecutive days) during the sprouting, vegetative growth, flowering and fruiting stages. Based on this, we analyzed the differential impacts of intense drought events at different phenophases on the phenotypic characteristics (e.g. shrub height, cover, volume, specific leaf area) and functional traits (ANPP accumulation and allocation) of A. ordosica. The experiment employed a randomized complete block design with three replicates for each treatment. The results indicate that: (1) Under intense drought events at different phenophases, all phenotypic characteristic indicators of A. ordosica significantly decreased. (2) Contrary to the significant negative correlation between twig number and twig size in response to rainfall variations, under intense drought conditions, there is a significant positive correlation between the two, indicating a synergistic effect. (3) The impact of intense drought events at different phenophases on the ANPP (aboveground net primary production) accumulation of A. ordosica varied significantly. The degree of impact is as follows: the flowering and fruiting stage > the sprouting stage > the vegetative growth stage. (4) A. ordosica adapted to intense drought by increasing the proportion of reproductive growth and decreasing the proportion of vegetative growth. Our results reveal the phenotypic and functional trait plasticity response mechanisms of A. ordosica to intense droughts at different phenophases, laying a foundation for predicting the impacts of climate change on desert ecosystems.