Patterns and driving factors of functional traits of desert species with different elevational distributions in the Tibetan Plateau and adjacent areas

Abstract

Variations in functional traits serve as measures of plants' ability to adapt to environment. Exploring the patterns of functional traits of desert plants along elevational gradients is helpful to understand the responses and adaptation strategies of species to changing environments. However, it is unknown whether the relationship between functional traits and elevation is affected by differences in the species' elevational distributions (elevation preference and species' range). Importantly, most researches have concerned with differences in mean trait values and ignored intraspecific trait variation. Here, we measured functional traits of desert plants along a wide elevational gradient in the Tibetan Plateau and adjacent areas and explored functional trait patterns over elevation in species with different elevational distributions. We decomposed trait variation and further investigated characterizations of intraspecific variation. Ultimately, the main drivers of trait variation were identified using redundancy analysis. We found that species' elevational distributions significantly influenced the relationship of functional traits such as plant height, leaf dry matter content, leaf thickness, leaf nitrogen and carbon content with elevation. Species with a lower elevational preference showed greater trait variation than species with a higher elevational preference, suggesting that species that prefer high elevation are more conservative facing environmental changes. We provide evidence that interspecific trait variation in leaf thickness and leaf carbon content decreased with increasing species' range, indicating that increased variations in resistance traits within species make greater responsiveness to environmental changes, enabling species a wider range. Elevation, temperature and precipitation were the main drivers of trait variation in species with a low elevational preference, while the effect of precipitation on trait variation in species with a high elevational preference was not significant. This study sheds new insights on how plants with different elevational distributions regulate their ecological strategies to cope with changing environments.

Keywords: Elevation; Functional trait; Intraspecific trait variation; Tibetan Plateau.

Fig. 1

Relationship between functional traits and elevation, as influenced by species elevational preference (EP). Functional traits: Plant height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (LT), leaf nitrogen content (LNC) and leaf carbon content (LCC). Shade areas are the 95% confidence intervals. cR² represents conditional R² value, and mR² represents marginal R² value. Trait values and elevation were standardized

Fig. 2

Relationship between functional traits and elevation, as influenced by species’ elevational range (SR). Functional traits: Plant height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (LT), leaf nitrogen content (LNC) and leaf carbon content (LCC). Shade areas are the 95% confidence intervals. cR² represents conditional R² value, and mR² represents marginal R² value. Trait values and elevation were standardized

Fig. 3

Variance decomposition of height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (LT), leaf nitrogen content (LNC) and leaf carbon content (LCC) measured across species with different elevational distributions. LN: species with low elevational preference and narrow species’ range; LW: species with low elevational preference and wide species’ range; HN: species with high elevational preference and narrow species’ range; HW: species with high elevational preference and wide species’ range. Colored bars show proportion of total trait variance (‘% trait Var’) while black bar shows absolute amount of variance (‘Tot trait Var’)

Fig. 4

Redundancy analysis of functional traits and environmental factors across species with different elevational distributions. Functional traits: plant height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (LT), leaf nitrogen content (LNC) and leaf carbon content (LCC). Environmental factors: elevation, annual mean temperature (Temp), annual mean precipitation (Prec), soil pH (pH), soil electrical conductivity (EC), soil clay content (Clay), soil sand content (Sand), soil nitrogen content (SNC) and soil carbon content (SCC). LN: species with low elevational preference and narrow species’ range; LW: species with low elevational preference and wide species’ range; HN: species with high elevational preference and narrow species’ range; HW: species with high elevational preference and wide species’ range. Red lines indicate functional traits, and blue lines indicate environmental factors