A threefold difference in plant growth response to nitrogen addition between the laboratory and field experiments

Abstract

Quantifying the magnitude of plant response to nitrogen (N) addition is critical in improving our understanding of vegetation productivity in terrestrial ecosystems. Numerous studies under both the laboratory (hereafter lab) and field conditions have shown significant increases in plant growth by N addition. However, differences exist when we integrate or compare the results between N-addition experiments under the lab and field conditions. Here, we performed a meta-analysis on observations from 139 field and 127 lab experiments to identify their differences and similarities in the N response of plant growth. Overall, there was a threefold difference in the N effect on plant biomass between the lab (+63.1%) and field (+22.2%) experiments. The magnitude of the lab-field difference varied among plant categories and plant tissues. For example, the larger N effect in the lab than field conditions was about twofold for the herbaceous plant but fourfold for the woody species. Furthermore, the N-induced increase in biomass was allocated more to above-ground parts in the field but equally to above-and below-ground parts under the lab conditions. We further showed that these differences were jointly attributed to the differential abiotic (i.e., environmental condition and N application methods) and biotic (i.e., interspecific interaction, age, and functional types) factors under these two experimental conditions. These findings highlight more attention should be paid when the results from the lab experiments are translated to understand the N response of the natural plants.

Global response patterns of plant photosynthesis to nitrogen addition: A meta‐analysis

“…For example, total leaf biomass (and consequently TLA) and A area were enhanced significantly in grass but not in forb (Figure 6a), suggesting that grass would outcompete forb under increased N availability. Consistent with our results, previous studies repeatedly reported that N addition/deposition significantly stimulated total or aboveground biomass of grass but not that of forb both across biomes (De Schrijver et al, 2011; Xia & Wan, 2008; Xu et al, 2019; You et al, 2017) and within a biome such as grasslands (Fu & Shen, 2016; Humbert, Dwyer, Andrey, & Arlettaz, 2016; Stevens, Dise, Gowing, & Mountford, 2006).…”

“…Given greater enhancement of TLA indicates greater enhancement of competition for light and space, the greater enhancement of TLA for broadleaf than conifer trees found here suggests that chronic N deposition gives broadleaves benefits relative to conifers in terms of light interception and consequently gross photosynthesis and growth. This inference is supported by results of two previous meta-analyses that N addition enhanced plant biomass more for broadleaf than conifer trees (Xia & Wan, 2008;Xu et al, 2019).…”

“…With large sample sizes, the average responses of total leaf biomass (+46.5%), leaf area per plant (+29.7%), and LAI (+24.1%) found here are stronger than those reported in previous meta‐analyses. For instance, Xia and Wan (2008), using 71 observations (i.e., n = 71), showed that total leaf biomass at the species level was increased by 14.7%, and with a larger sample size ( n = 103), they updated the value to 33.2%–36.2% (Xu, Yan, & Xia, 2019). Li et al (2016) found that total leaf biomass of trees was increased by 20.9% but leaf area per plant did no change significantly, and Zhang et al (2018) reported LAI of woody plants to increase significantly by 10.3%.…”

A Comparison of Linear Conventional and Nonlinear Microbial Models for Simulating Pulse Dynamics of Soil Heterotrophic Respiration in a Semi‐Arid Grassland

“…Some laboratory‐based experiments have suggested that the response of soil C to drying‐rewetting events could be better explained by microbial models because they represented more realistic mechanisms of soil C‐cycle processes (Manzoni et al., 2014, 2016; Salazar et al., 2018). There are great differences between laboratory experiments and field experiments (Poorter et al., 2016; Xu et al., 2019). Meanwhile, the development of microbial models must link micro‐scale mechanisms to macro‐scale models, which has to face several challenges compared to linear models, such as parameterization (Luo & Schurr, 2020; Wieder, Allison, et al., 2015).…”

Research challenges and opportunities for using big data in global change biology

“…For example, plant and animal phenology have been monitored in both natural and urban regions (Harrison, Gibbs, & Winfree, 2019; Li, Stucky, et al, 2019; Wohlfahrt, Tomelleri, & Hammerle, 2019). Also, there are large differences in species‐level biomass (Poorter et al., 2016) and its response to environmental changes (Xu, Yan, et al, 2019a) between controlled and field experiments. Plant photosynthesis is one of the most important processes in driving biological responses to global changes but has been measured by different portable photosynthesis systems, such as LI 6400 and LI 6800 (Li‐Cor), GFS‐3000 (Walz), CID‐CI340 (Bio‐Science), CIRAS‐3 (PP Systems) and LCi‐SD (ADC BioScientific).…”