Responses of plant phenology to nitrogen addition: a meta‐analysis

Abstract

Phenology is one of the most sensitive processes of plant in response to global change. Anthropogenic activities have considerably increased nitrogen (N) deposition, which significant affects plant phenology. Although numerous individual studies have been conducted, it remains controversial how N addition affects phenological stages, and a comprehensive understanding of how plant phenology responds to external N inputs remains elusive. To reconcile the differences, we conducted a meta‐analysis of 117 species to examine the responses of plant phenology to N addition in terrestrial ecosystems, and assessed variations in their responses in relation to ecosystem types, functional groups, and environmental conditions. Our results showed that plant phenology changed significantly after N addition, and phenology time delayed and phenology duration shortened significantly across all biomes except fruiting duration, but varied with biome types. The phenology change in cropland was more dramatical than in grassland after N addition, even in opposite directions. The response of phenological stages to N addition was consistent in two pollination types except the flowering time, the flowering time had no change in anemophilous but significantly delayed in entomophilous. In addition, the response of phenology to N addition was discrepancy among functional groups, the phenology time advanced and duration shortened in sedge, while phenology time delayed and duration shortened in other groups, and the phenology change in legume was larger than grass and forbs. We also found that environmental factors had little effects on the response of plant phenology to N addition, but significant correlation was found between the response ratios of different phenological stages. Our study suggested that phenology was sensitive to N deposition at many phenological stages, and changes in phenology may be smaller with community biodiversity increasing at ecosystem level.

Extirpated prairie species demonstrate more variable phenological responses to warming than extant congeners

“…Phenology, or the timing of life history events, is critical to fitness and population persistence (Parmesan and Yohe, 2003; Cleland et al, 2007). While some species and populations exhibit little phenological plasticity (i.e., shift their phenology little in response to environmental variation), other species and populations respond strongly to temperature and precipitation (Visser and Both, 2005; Matthews and Mazer, 2016; Thackeray et al, 2016; Cremonense et al, 2017) and other environmental variables such as nutrient availability or competition (Smith et al, 2012; Xia and Wan, 2013; Du et al, 2019; Wang and Tang, 2019). Phenological plasticity may promote population growth (or limit population declines) in the face of climate change and has been associated with invasiveness and range size (Crawley et al, 1996; DeFalco et al, 2007; Willis et al, 2008, 2010; Cleland et al, 2012; Pearson et al, 2012; Wolkovich et al, 2013; Lustenhouwer et al, 2018; Zettlemoyer et al, 2019b; Reeb et al, 2020), suggesting that species that are less phenologically plastic may be more at risk of population declines and eventual extirpation (Møller et al, 2008; Willis et al, 2008; Forrest and Miller‐Rushing, 2010; Miller‐Rushing et al, 2010).…”

Impacts of nitrogen enrichment on vegetation growth dynamics are regulated by grassland degradation status

“…As a convention, former studies often divided grassland species into two groups of grasses and forbs or into four groups of grasses, sedges, forbs, and legumes (Wang & Tang, 2019). Existing research identified contrasting phenological responses of grasses and forbs to N addition (Cleland et al, 2006;Smith et al, 2012;Xia & Wan, 2013).…”

“…Our results showed that forbs that include many different species did not correlate with any phenophases, and grasses only correlated with the length of growing season at a lower strength than expected. Since Cyperaceous plants can initiated life-history earlier under N enrichment (Ren et al, 2016) and include late-flower sedge (Stenström & Jónsdóttir, 1997), they can have significant impacts on the end of growing season and have been reported to perform differently with other groups (Wang & Tang, 2019). In fact, varying grasses may have significantly different responses or even in contrasting directions to environmental variations (e.g., perennial grasses and annual grasses),…”

“…However, other anthropogenic environmental factors, such as nitrogen (N) enrichment, also play important roles in the rapid global change (Galloway et al, 2008) and can profoundly influence the composition and functions of vegetation (Isbell, Tilman, Polasky, Binder, & Hawthorne, 2013;Storkey et al, 2015). As the main nutrient element for most plants, N can also have profound impacts on the growth rates and reproductive allocations (Tilman & Wedin, 1991), and thus, regulate phenology (Wang & Tang, 2019).…”

Climate warming extends growing season but not reproductive phase of terrestrial plants

“…Generally, plant phenology was divided into the following 10 stages: leaf‐out (stage 0), budding (stage 1), flowering (stage 2), post‐anthesis (stage 3), initiated fruiting (stage 4), expanding fruiting (stage 5), dehisced fruit (stage 6), disarticulated seeds (stage 7), post‐fruit leafing (stage 8) and leaf colouring (stage 9) (see Supporting Information Figure S2). Based on previous studies (Dunne et al., 2003; Sherry et al, 2007; Wang & Tang, 2019), the time difference between budding and flowering was defined as the flower bud duration, between flowering and post‐anthesis was defined as flowering duration, and between initiated fruiting and dehisced fruit was defined as fruiting duration in our study. The reproductive phase was calculated as the time between budding and disarticulated seeds, and growing season length was calculated as the time between leaf‐out and leaf colouring.…”