Nitrogen fertilization, not water addition, alters plant phylogenetic community structure in a semi‐arid steppe

Abstract

Anthropogenic environmental changes, such as nitrogen (N) enrichment and alteration in precipitation regimes, significantly influence ecosystems world‐wide. However, we know little about whether and how these changes alter the phylogenetic properties of ecological communities. Based on a 7‐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. 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. In 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 trait‐based species extinction where shorter statured plants and shallower rooted plants were at greater risk of extinction. 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.

Warming alters plant phylogenetic and functional community structure

“…This trend has been largely driven by the recognition that species functional traits, not identity, determine their performance and interactions with other species (McGill et al, 2006;Violle et al, 2007), and that species phylogenetic relationships can often serve as a reasonable proxy of similarity in their functional traits, including potentially important, but unidentified or unmeasured traits (Donoghue, 2008;Peterson, Soberon, & Sanchez-Cordero, 1999;Prinzing, Durka, Klotz, & Brandl, 2001). More recently, global change biologists have also began to adopt the phylogenetic and functional perspectives to study the responses of ecological communities to global change stressors (Lavergne, Mouquet, Thuiller, & Ronce, 2010;Willis, Ruhfel, Primack, Miller-Rushing, & Davis, 2008;Yang et al, 2018Yang et al, , 2019. Nevertheless, little is known about how climate warming, an important facet of global environmental changes (IPCC, 2013), influences phylogenetic and functional properties of ecological communities (but see Li, Miller, & Harrison, 2019).…”

“…For example, Li et al (2015) reported that the observed long-term old-field succession towards phylogenetic and functional overdispersion in New Jersey, USA, was due to the colonization of species distantly related to the resident species, not the extinction of closely related resident species. Likewise, Yang et al (2018) found that nitrogen fertilization into a temperate grassland in Inner Mongolia, China, promoted the colonization of species distantly related to residents, resulting in community phylogenetic overdispersion. It is thus essential to examine species extinction and colonization together for a better understanding of warming-induced changes in community phylogenetic/functional structure.…”

Past is prologue: host community assembly and the risk of infectious disease over time

“…Increased resource supply can either increase or reduce phylogenetic overdispersion. Increased resource supply can increase phylogenetic overdispersion by promoting the colonisation of more distantly related species and increasing competitive exclusion between closely related species (Yang et al 2018). Alternatively, increased resource supply can reduce phylogenetic overdispersion when traits related to nutrient uptake and allocation are phylogenetically conserved (Verboom et al 2017), by favouring clades with specific resource uptake and allocation strategies ( Fig.…”

Resource addition drives taxonomic divergence and phylogenetic convergence of plant communities

“…The temperate steppe in this area is currently experiencing significant anthropogenic environmental changes, including increased N deposition and precipitation (Chen et al, ; Niu et al, ; Xia, Niu, & Wan, ), necessitating a thorough understanding of their ecological consequences. Previous work at the study site has documented changes in a number of community and ecosystem properties, including functional group composition (Yang et al, ), ecosystem productivity, respiration and net C exchange (Niu et al, , ), community stability (Yang et al, ) and plant phylogenetic community structure (Yang et al, ), in response to experimental manipulations of N and precipitation. However, the question of how these environmental changes affect the trajectory of community assembly remains unanswered.…”