Drought responses of three closely related Caragana species: implication for their vicarious distribution

Abstract

Drought is a major environmental constraint affecting growth and distribution of plants in the desert region of the Inner Mongolia plateau. Caragana microphylla, C. liouana, and C. korshinskii are phylogenetically close but distribute vicariously in Mongolia plateau. To gain a better understanding of the ecological differentiation between these three species, we examined the leaf gas exchange, growth, water use efficiency, biomass accumulation and allocation by subjecting their seedlings to low and high drought treatments in a glasshouse. Increasing drought stress had a significant effect on many aspects of seedling performance in all species, but the physiology and growth varied with species in response to drought. C. korshinskii exhibited lower sensitivity of photosynthetic rate and growth, lower specific leaf area, higher biomass allocation to roots, higher levels of water use efficiency to drought compared with the other two species. Only minor interspecific differences in growth performances were observed between C. liouana and C. microphylla. These results indicated that faster seedling growth rate and more efficient water use of C. korshinskii should confer increased drought tolerance and facilitate its establishment in more severe drought regions relative to C. liouana and C. microphylla.

Spatial Variation in Leaf Stable Carbon Isotope Composition of Three Caragana Species in Northern China

“…As previously reported, leaf δ 13 C is related to WUE and plants with higher δ 13 C or WUE tend to have a higher drought tolerance during periods of low water availability [10,16,19,23]. The present results indicated that the mean leaf δ 13 C was highest in C. korshinskii, intermediate in C. liouana, and lowest in C. microphylla, with the differences being significant (Figure 3), which is consistent with results from previous studies [51,52]. Although the growth range of C. microphylla occurs across a relatively wider altitudinal and temperature gradient, the pluviometric range is limited and tends to be higher than the growth ranges of the other two species, which probably results in lower values of δ 13 C for C. microphylla than in the other two species.…”

“…The growth range of C. korshinskii appears to be characterized by lower precipitation than the area where C. liouana grows ( Table 1, Table S1), which results in the highest values of leaf δ 13 C among the three species. In a previous study examining the ecophysiological responses of these three species to water stress [51], we also found that C. korshinskii exhibits lower sensitivity of the photosynthetic rate and growth, a lower specific leaf area, higher biomass allocation to roots, and higher levels of water use efficiency to drought compared with the other two species. Taken together, these results support differentiation in drought tolerance among the three species because of long-term adaptation to distinct water availability conditions.…”

“…Previously, we have found that these three species diverge substantially in growth and physiological parameters in response to drought stress during a controlled experiment. C. korshinskii appeared to be the most drought-tolerant species with a superior growth rate and water use efficiency compared to the other two species [51,52]. As such, evaluating the patterns and environmental controls of δ 13 C in these three species will not only help predict how these species respond to future climate change, but will also provide evidence for the physiological mechanisms underlying the distribution pattern of these three closely related Caragana species.…”

Effects of Soil Microbes on Functional Traits of Loblolly Pine (Pinus taeda) Seedling Families From Contrasting Climates

“…One proposed mechanism underlying this observation is that the slightly greater height of the dry inoculated group compared to dry control group (albeit not significant) resulted in increased leaf area which may have contributed to faster desiccation and functional decline during drought. Another possible mechanism underlying the dry inoculated group's F V /F M decline may be related to the opposite (albeit not significant) effect sizes between families for %N and consequently C:N. In the wet family, we observed a positive treatment effect size on leaf %N and a negative effect size on C:N, while in contrast, the dry family exhibited the opposite: a negative effect size on leaf %N and a positive effect size on C:N. Increased C:N, as we observed in the dry inoculated group, can indicate greater drought stress (Chen et al, 2015;Ma et al, 2016). This may possibly be due to a negative interaction between the soil microbes and the dry family.…”

Precipitation is the main factor affecting the variation of foliar nitrogen isotope composition in two leguminous shrub species of northwestern China

“…The genus Caragana belongs to the family Leguminosae and is well known for its role in controlling soil erosion and land desertification, and for its economic values as a honey source, fuel and fodder in China [7]. Because of the great environmental and economic benefits, this genus has attracted increasing attention in ecological research [7][8][9]. In this study, we selected two of the most common Caragana species, Caragana korshinskii and Caragana liouana, which are two dominant shrub species in the desert regions of northern China.…”