Plant traits are differentially linked to performance in a semiarid ecosystem

Biomod2 modeling for predicting the potential ecological distribution of three Fritillaria species under climate change

The Fritillaria species ranked as a well-known traditional medicine in China and has become rare due to excessive harvesting. To find reasonable strategy for conservation and cultivation, identification of new ecological distribution of Fritillaria species together with prediction of those responses to climate change are necessary. In terms of current occurrence records and bioclimatic variables, the suitable habitats for Fritillaria delavayi, Fritillaria taipaiensis, and Fritillaria wabuensis were predicted. In comparison with Maxent and GARP, Biomod2 obtained the best AUC, KAPPA and TSS values of larger than 0.926 and was chosen to construct model. Temperature seasonality was indicated to put the greatest influence on Fritillaria taipaiensis and Fritillaria wabuensis, while isothermality was of most importance for Fritillaria delavayi. The current suitable areas for three Fritillaria species were distributed in south-west China, accounting for approximately 17.72%, 23.06% and 20.60% of China's total area, respectively. During 2021-2100 period, the suitable habitats of F. delavayi and F. wabuensis reached the maximum under SSP585 scenario, while that of F. taipaiensis reached the maximum under SSP126 scenario. The high niche overlap among three Fritillaria species showed correlation with the chemical composition (P ≤ 0.05), while no correlation was observed between niche overlap and DNA barcodes, indicating that spatial distribution had a major influence on chemical composition in the Fritillaria species. Finally, the acquisition of species-specific habitats would contribute to decrease in habitat competition, and future conservation and cultivation of Fritillaria species.

Traits that distinguish dominant species across aridity gradients differ from those that respond to soil moisture

Many plant traits respond to changes in water availability and might be useful for understanding ecosystem properties such as net primary production (NPP). This is especially evident in grasslands where NPP is water-limited and primarily determined by the traits of dominant species. We measured root and shoot morphology, leaf hydraulic traits, and NPP of four dominant North American prairie grasses in response to four levels of soil moisture in a greenhouse experiment. We expected that traits of species from drier regions would be more responsive to reduced water availability and that this would make these species more resistant to low soil moisture than species from wetter regions. All four species grew taller, produced more biomass, and increased total root length in wetter treatments. Each species reduced its leaf turgor loss point (TLP) in drier conditions, but only two species (one xeric, one mesic) maintained leaf water potential above TLP. We identified a suite of traits that clearly distinguished species from one another, but, surprisingly, these traits were relatively unresponsive to reduced soil moisture. Specifically, more xeric species produced thinner roots with higher specific root length and had a lower root mass fraction. This suggest that root traits are critical for distinguishing species from one another but might not respond strongly to changing water availability, though this warrants further investigation in the field. Overall, we found that NPP of these dominant grass species responded similarly to varying levels of soil moisture despite differences in species morphology, physiology, and habitat of origin.

Responses of root system architecture to water stress at multiple levels: A meta-analysis of trials under controlled conditions

Plants are exposed to increasingly severe drought events and roots play vital roles in maintaining plant survival, growth, and reproduction. A large body of literature has investigated the adaptive responses of root traits in various plants to water stress and these studies have been reviewed in certain groups of plant species at a certain scale. Nevertheless, these responses have not been synthesized at multiple levels. This paper screened over 2000 literatures for studies of typical root traits including root growth angle, root depth, root length, root diameter, root dry weight, root-to-shoot ratio, root hair length and density and integrates their drought responses at genetic and morphological scales. The genes, quantitative trait loci (QTLs) and hormones that are involved in the regulation of drought response of the root traits were summarized. We then statistically analyzed the drought responses of root traits and discussed the underlying mechanisms. Moreover, we highlighted the drought response of 1-D and 2-D root length density (RLD) distribution in the soil profile. This paper will provide a framework for an integrated understanding of root adaptive responses to water deficit at multiple scales and such insights may provide a basis for selection and breeding of drought tolerant crop lines.

Linking leaf traits to the temporal stability of above- and belowground productivity under global change and land use scenarios in a semi-arid grassland of Inner Mongolia

The biotic drivers for the temporal stability of aboveground net productivity (ANPP) in natural ecosystems are well understood. However, knowledge gaps still exist regarding the relative importance of biotic and abiotic drivers regulating the temporal stability of aboveground productivity (ANPP), belowground net productivity (BNPP), and community net productivity (NPP) under global change and land use scenarios. Thus, in this study, we aimed to study the effects of increased water and nitrogen availability on temporal stability of ANPP, BNPP, and NPP and underlying mechanisms at sites with different long-term grazing histories in typical grasslands of the Inner Mongolia. The results suggested that resource addition affected the ANPP stability, but it did not change the stability of BNPP and NPP, which were all mediated by grazing histories. Most importantly, our study further indicated that species asynchrony, primarily contributed to the stability of ANPP and NPP by weakening their variation, and species asynchrony was regulated directly by plant diversity-related variables and indirectly by soil variables which were affected by resource addition and grazing history. In addition, an increase of ANPP stimulated under resource addition was a secondary contributor to ANPP stability. Specifically, the community-weighted mean of specific leaf area (CWM SLA) regulated the ANPP stability indirectly by promoting species asynchrony, while functional diversity of leaf area and SLA both directly controlled the BNPP stability. Findings of our study demonstrate that different mechanisms drove temporal stability of above- and belowground productivity. Our study has important implications for maintaining the temporal stability of community productivity and for establishing sustainable management practices of semi-arid grasslands under global change and land use scenarios.