title: Beyond dual-lattice models: incorporating plant strategies when modeling the interplay between facilitation and competition along environmental severity gradients.
abstract: We introduce a spatially explicit model that evaluates how the trade-offs between the life strategies of two interacting plant species affect the outcome of their interaction along environmental severity gradients. In our model, we represent the landscape as a two-dimensional lattice, with environmental severity increasing from left to right. Two species with different strategies, a competitor and a stress-tolerant, interact in the lattice. We find that facilitation expands the realized niche of the competitor into harsh environments by suppressing the stress-tolerant species. Most of their coexisting range is dominated by a positive effect of one species on another, with a reciprocal negative effect from the species receiving the benefits on its benefactor ("+, -"), whereas mutualistic ("+, +") interactions are only found in the harshest part of the environmental gradient. Contrarily as assumed by models commonly used in facilitation research (e.g. dual-lattice models), our results indicate that "+, +" interactions are not dominant, and that their differences with "+, -" interactions along environmental severity gradients depend on the strategies of the interacting species. By integrating the trade-off between competitive ability and stress tolerance, our model provides a new framework to investigate the interplay of facilitative and competitive interactions along environmental gradients and their impacts on processes such as population dynamics and community organization.
authors.affiliation: MOE Key Laboratory of Arid and Grassland Ecology, School of Life Science, Lanzhou University, Lanzhou 730000, People's Republic of China. chenshy@lzu.edu.cn
authors.forename: Shu-Yan
authors.initials: SY
authors.lastname: Chen
authors.forename: Jin
authors.initials: J
authors.lastname: Xu
authors.forename: Fernando T
authors.initials: FT
authors.lastname: Maestre
authors.forename: Cheng-Jin
authors.initials: CJ
authors.lastname: Chu
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.forename: Sa
authors.initials: S
authors.lastname: Xiao
mesh_terms: D003198:Computer Simulation; D017753:Ecosystem; D004777:Environment; D008954:Models, Biological; D063245:Plant Development; D011156:Population Density; D011157:Population Dynamics