Grazing effects on intraspecific trait variability vary with changing precipitation patterns in Mongolian rangelands

Abstract

Functional traits are proxies for plant physiology and performance, which do not only differ between species but also within species. In this work, we hypothesized that (a) with increasing precipitation, the percentage of focal species which significantly respond to changes in grazing intensity increases, while under dry conditions, climate-induced stress is so high that plant species hardly respond to any changes in grazing intensity and that (b) the magnitude with which species change their trait values in response to grazing, reflected by coefficients of variation (CVs), increases with increasing precipitation. Chosen plant traits were canopy height, plant width, specific leaf area (SLA), chlorophyll fluorescence, performance index, stomatal pore area index (SPI), and individual aboveground biomass of 15 species along a precipitation gradient with different grazing intensities in Mongolian rangelands. We used linear models for each trait to assess whether the percentage of species that respond to grazing changes along the precipitation gradient. To test the second hypothesis, we assessed the magnitude of intraspecific trait variability (ITV) response to grazing, per species, trait, and precipitation level by calculating CVs across the different grazing intensities. ITV was most prominent for SLA and SPI under highest precipitation, confirming our first hypothesis. Accordingly, CVs of canopy height, SPI, and SLA increased with increasing precipitation, partly confirming our second hypothesis. CVs of the species over all traits increased with increasing precipitation only for three species. This study shows that it remains challenging to predict how plant performance will shift under changing environmental conditions based on their traits alone.In this context, the implications for the use of community-weighted mean trait values are discussed, as not only species abundances change in response to changing environmental conditions, but also values of traits considerably change. Including this aspect in further studies will improve our understanding of processes acting within and among communities. K E Y W O R D S environmental gradients, grasslands, intraspecific trait variability, land-use, rainfall, steppes S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Lang B, Ahlborn J, Oyunbileg M, et al. Grazing effects on intraspecific trait variability vary with changing precipitation patterns in Mongolian rangelands. Ecol

Leaf Waxes and Hemicelluloses in Topsoils Reflect the δ2H and δ18O Isotopic Composition of Precipitation in Mongolia

“…overall harsh conditions (Dashkhuu et al, 2015). Especially the vegetation period, during which biosynthesis can take place, is very short and corresponds with the summer months June, July, and August, when ∼75% of the annual precipitation occurs ( Figures 1D,E, 2H; Lang et al, 2020).…”

Mammalian herbivory shapes intraspecific trait responses to warmer climate and nutrient enrichment

“…In contrast, inherently small-statured species, that can avoid being grazed may benefit from nutrients and competition-free environment in grazed systems. Our results, therefore, emphasize that intraspecific trait plasticity is also controlled by different factors for different species (Albert et al, 2010;Lang et al, 2020;Liancourt et al, 2015) and more research is needed to disentangle which inherent properties of species dictate these responses.…”

Single Grazing Is More Detrimental to Grasslands Than Mixed Grazing: Evidence From the Response of Functional Traits of Dominant Plants to Grazing Systems

“…For each species and trait, we calculated the ITV as the coefficient of variation (CV), which is computed as the standard deviation of each grazing system (six replicates) divided by the mean (Lang et al, 2020).…”

“…ITV also helps to explain how certain species pass through biological and abiotic filters and consequently promote species coexistence (Jung et al, 2010;de la Riva et al, 2016). Lang et al (2020) found that the "ITV response to grazing" increases with an increase in precipitation in the Mongolian rangelands. High ITV at the population level may arise from differences in ecological factors, such as soil texture and successional stage (Albert et al, 2011;Salazar et al, 2018).…”

“…In the grassland ecosystem of Inner Mongolia, researchers have paid more attention to the effects of grazing vs. non-grazing and of grazing intensity on plant functional traits (Bai et al, 2012;Zhang et al, 2018). Few studies, however, have examined the effect of different grazing systems on plant functional traits in dominant species, and few studies have focused on ITV under different grazing systems (Lang et al, 2020). Here, we characterized the response of the dominant species in the Inner Mongolia grassland to different grazing systems and asked the following questions:…”