Data from: Nitrogen fertilization, not water addition, alters plant phylogenetic community structure in a semi-arid steppe

1. Anthropogenic environmental changes, such as nitrogen (N) enrichment
and alteration in precipitation regimes, significantly influence
ecosystems worldwide. However, we know little about whether and how these
changes alter the phylogenetic properties of ecological communities. 2.
Based on a seven-year field experiment in the temperate semi-arid steppe
of Inner Mongolia, China, we investigated the influence of increased N and
precipitation on plant phylogenetic structure and phylogenetic patterns of
species colonization and extinction. 3. Our study demonstrated that N and
water addition influenced different aspects of plant community structure.
Water addition increased plant species richness by preventing species
extinction and facilitating species colonization, without altering
community phylogenetic structure. By contrast, N addition did not alter
species richness, but promoted the colonization of species distantly
related to the residents, changing community phylogenetic structure from
being neutral to overdispersion. We also found evidence for
abundance-based extinction where rarer species were at greater risk of
extinction, and functional-based species extinction where shorter-statured
plants and shallower-rooted plants were at greater risk of extinction. 4.
Synthesis. Our study provides the first experimental evidence that plant
phylogenetic community structure responds differently to different aspects
of global changes. Importantly, the colonization of non-resident species,
rather than the extinction of resident species, contributed predominantly
to changes in plant community phylogenetic structure in response to N
amendment. Our findings highlight the importance of considering species
phylogenetic relationships for a more complete understanding of
anthropogenic influences on ecological communities.