From Ordinary to Extraordinary: The Crucial Role of Common Species in Desert Plant Community Stability with Arbuscular Mycorrhizal (AM) Fungi Under Increased Precipitation

Abstract

Climate change is altering precipitation patterns in Central Asia's arid zones, destabilizing desert ecosystems. Arbuscular mycorrhizal (AM) fungi, key soil microorganisms forming symbiosis with most plants, critically maintain ecosystem stability, yet their mechanisms in regulating individual plant species to sustain community stability remain unclear. We conducted a 5-year in situ experiment in the Gurbantunggut Desert, testing how AM fungi influence desert plant community stability under increased precipitation. Using a randomized block design with three treatments-control (CK), increased precipitation (W), and precipitation with Benomyl fungicide (BW)-we monitored plant community dynamics. We discovered that both increased precipitation and AM fungi altered plant community structure without affecting diversity. Precipitation boosted aboveground net primary productivity (ANPP) and density, enhancing community stability via dominant species (e.g., Meniocus linifolius), supporting the mass ratio hypothesis. AM fungi further stabilized the community by increasing ANPP and enhancing the common species stability under increased precipitation, while the contribution of rare species was also non-negligible, aligning with the subordinate insurance hypothesis. Overall, our study elucidates how increased precipitation and AM fungi regulate plant community stability at the species level. Specifically, it overcomes key gaps by revealing AM fungi's pivotal role in stabilizing communities through sustaining common species stability.

Keywords: Central Asian deserts; arbuscular mycorrhizal fungi; common species stability; increased precipitation; subordinate insurance hypothesis; temporal stability.

Figure 1

The ANPP (above-ground net primary productivity) (a), Shannon–Wiener index (b), Simpson’s diversity index (c), Pielou’s evenness index (d), plant density (e), and species richness (f) of the plant community under increased precipitation (W) and suppression of AM fungi (BW) during 2005–2009. Different bars indicate the mean value ± SE for the treatment. * and ** indicate statistical significance at p ≤ 0.05 and p ≤ 0.01, respectively. Different lowercase letters indicate significant differences among snow manipulation levels under major treatments (p < 0.05, Fisher’s LSD test). And ns indicate no significant differences. Y, year; CK, control; W, only water addition; BW, Benomyl with water. Same as the following.

Figure 2

The relative biomass of each species and rare species overall within the plant community under increased precipitation (W) and suppression of AM fungi (BW) during 2005–2009. Orange represents 6 dominant species, blue represents 9 common species, and red represents overall rare species.

Figure 3

M. Godron stability fitted the curve of the plant community under increased precipitation (W) and suppression of AM fungi (BW) during 2005–2009. Points colored according to treatments represent the actual coordinates of each species under the corresponding treatment. The red dot on the straight line represents the reference point (20, 80).

Figure 4

Structural equation modeling results of the effect of increased precipitation (a) (p = 0.928; RMSEA = 0.000; GFI = 0.951; AIC = 262.275; df = 10) and AM fungi (b) (p = 0.063; RMSEA = 0.203; GFI = 0.766; AIC = 313.860; df = 13) on plant community stability. Blue and red arrows denote significant positive and negative associations, respectively, while grey arrows indicate non-significant correlations. The arrow width is proportional to the strength of the relationship. Significance level: *** p < 0.001, ** p < 0.01, * p < 0.05 and † p < 0.1. Values along the arrows are standardized path coefficients, which represent relationships between variables. The R² values, representing the proportion of variance explained, are presented along with the response variables in each analysis.

Figure 5

Random forests (RFs) analysis quantified the relative importance of individual species stability and rare species stability in determining plant community stability under increased precipitation (a) and AM fungi presence (b) (* p  <  0.05). Light blue indicates significant contributions, while dark blue denotes non-significant contributions.

Figure 6

Study area location ((a); map created by authors), experimental design schematic ((b); designed by T. Zhang), and field implementation photographs ((c); photo credit: T. Zhang) [114]. The map in panel (a) was first generated for this study using Landsat-7 ETM+ imagery (USGS). CK, control; W, only water addition; BW, Benomyl with water.