Inter-annual precipitation fluctuation shapes plant communities
regardless of fertilization addition and mycorrhizal suppression in
desert steppe
Abstract
Intensified inter-annual precipitation fluctuation has profoundly
altered the structure and functioning of grassland ecosystems. However,
it remains elusive how fertilisation and arbuscular mycorrhizal (AM)
fungi affect plant communities under a variable precipitation regime. We
tested the interactive effects of inter-annual precipitation
fluctuation, nutrient addition (nitrogen, N and phosphorus, P) and
suppression of AM fungi on aboveground net primary productivity (ANPP)
and the species composition of plant community of a desert steppe for
two consecutive years (2019 and 2020). Our study demonstrated that
inter-annual precipitation fluctuation had a greater impact on ANPP and
the species composition of plant community than N and P addition and AM
fungi, suggesting that the impacts of fertilisation and AM fungi varied
by year and may be difficult to predict over time. In a normal year
(2019), N and P inputs altered the ANPP and the species composition of
plant community via enhancing the biomass and dominance of annual
species but had few impacts on the same parameters in a dry year (2020).
AM fungi had only a minimal effect on plant communities across the two
years. P input alone slightly enhanced plant species richness and
diversity. Our results indicate that plant community responses to
nutrient enrichment and AM fungi could be changed by inter-annual
precipitation fluctuation and that precipitation is a key factor
affecting plant communities in desert steppe.