Geographical patterns and environmental influencing factors of variations in Asterothamnus centraliasiaticus seed traits on Qinghai-Tibetan plateau

IntroductionSeed traits related to recruitment directly affect plant fitness and persistence. Understanding the key patterns and influencing factors of seed trait variations is conducive to assessing plant colonization and habitat selection. However, the variation patterns of the critical seed traits of shrub species are usually underrepresented and disregarded despite their vital role in alpine desert ecosystems.MethodsThis study gathered seeds from 21 Asterothamnus centraliasiaticus populations across the Qinghai-Tibetan Plateau, analyzing geographical patterns of seed traits to identify external environmental influences. Additionally, it explored how seed morphology and nutrients affect germination stress tolerance, elucidating direct and indirect factors shaping seed trait variations.ResultsThe results present substantial intraspecific variations in the seed traits of A. centraliasiaticus. Seed traits except seed length-to-width ratio (LWR) all vary significantly with geographic gradients. In addition, the direct and indirect effects of climatic variables and soil nutrients on seed traits were verified in this study. Climate mainly influences seed nutrients, and soil nutrients significantly affect seed morphology and seed nutrients. Furthermore, climate directly impacts seed germination drought tolerance index (GDTI) and germination saline-alkali tolerance index (GSTI). Seed germination cold tolerance index (GCTI) is influenced by climate and soil nutrients (mostly SOC). GDTI and GSTI are prominently influenced by seed morphology (largely the seed thousand-grain weight (TGW)), and GCTI is evidently affected by seed nutrients (mainly the content of soluble protein (CSP)).DiscussionThe findings of this study amply explain seed trait variation patterns of shrubs in alpine desert ecosystems, possessing significant importance for understanding the mechanism of shrub adaptation to alpine desert ecosystems, predicting the outcomes of environmental change, and informing conservation efforts. This study can be a valuable reference for managing alpine desert ecosystems on the Qinghai-Tibetan Plateau

Characteristics of the aboveground biomass and diversity along altitudinal gradients in alpine meadows of the upper reaches of the Yarlung Zangbo River

Abstract [Objective] The Yarlung Zangbo River is the most important river in the Tibetan Plateau, and the study of aboveground biomass and species diversity of the Yarlung Zangbo River is of great significance for the understanding of grassland resources and ecological conservation in the region. [Methods] This study investigated the characteristics of vegetations along elevation gradients in the alpine meadows in the upper reaches of the Yarlung Zangbo River, the distributional differences of aboveground biomass and species diversity along the gradients, and the relationship between aboveground biomass and species diversity. We also studied the effects of environmental factors on aboveground biomass and species diversity. [Results] (1) There was no significant relationship between aboveground biomass and elevation, temperature and precipitation (P >0.05). (2) Species diversity indices showed a significant negative correlation with elevations, and the Shannon-Weiner index (H ) and Patrick index (R) showed a declining trend with elevation. Species diversity showed a significant positive correlation with temperature and precipitation (P <0.05). (3) Aboveground biomass and diversity showed a negative correlation, and the explanation of aboveground biomass by the Shannon-Weiner index (H ) reached 70% (P <0.01). [Conclusion] There was no significant correlation between aboveground biomass and elevation, and species diversity indices showed a significant negative correlation with elevation. These results provide basis for the rational utilization of grassland resources and species diversity conservation in the upper reaches of the Yarlung Zangbo River basin

Morphology, photosynthetic physiology and biochemistry of nine herbaceous plants under water stress

Global climate warming and shifts in rainfall patterns are expected to trigger increases in the frequency and magnitude of drought and/or waterlogging stress in plants. To cope with water stress, plants develop diverse tactics. However, the adoption capability and mechanism vary depending upon the plant species identity as well as stress duration and intensity. The objectives of this study were to evaluate the species-dependent responses of alpine herbaceous species to water stress. Nine herbaceous species were subjected to different water stresses (including moderate drought and moderate waterlogging) in pot culture using a randomized complete block design with three replications for each treatment. We hypothesized that water stress would negatively impact plant growth and metabolism. We found considerable interspecies differences in morphological, physiological, and biochemical responses when plants were exposed to the same water regime. In addition, we observed pronounced interactive effects of water regime and plant species identity on plant height, root length, root/shoot ratio, biomass, and contents of chlorophyll a, chlorophyll b, chlorophyll (a+b), carotenoids, malondialdehyde, soluble sugar, betaine, soluble protein and proline, implying that plants respond to water regime differently. Our findings may cast new light on the ecological restoration of grasslands and wetlands in the Qinghai-Tibetan Plateau by helping to select stress-tolerant plant species

Establishment of Elymus natans improves soil quality of a heavily degraded alpine meadow in Qinghai-Tibetan Plateau,

Abstract Elymus natans is a dominant native species widely planted to restore the heavily degraded alpine meadows in Qinghai-Tibetan plateau. The objective of this study was to determine how E. natans establishment affected the quality and fertility of a heavily degraded soil. Soil samples (at depths of 0-10, 10-20 and 20-30 cm) were collected from the 3-and 7-year-old E. natans re-vegetated grasslands, and in the heavily degraded alpine meadow (control). The establishment of E. natans promoted plant cover and aboveground biomass. Compared to the non-reseeded meadow, the concentration of total organic C increased by 13% in the soil under 3-year-old reseeded E. natans grassland at 0-10 cm, and by 7-33% in the soil under 7-year-old reseeded E. natans grassland at 0-10, 10-20 and 20-30 cm depths. Rapid increases in total and available N were also observed in two E. natans re-vegetated grasslands, especially in the 0-10 cm soil layer. Across three sampling depths, total P concentration was increased by 17-35% and 18-54% in 3-and 7-year-old reseeded soil respectively, compared to the soil of control. After 3 years of E. natans growth, microbial biomass C increased by 13-58% at 0-10 and 10-20 cm layers; while it increased by 43-87% in 7-year-old reseeded treatment at 0-10, 10-20 and 20-30 cm depths relative to control. A similar increasing trend was observed for microbial biomass N and P generally. Significant increase in neutral phosphatase, urease, catalase and dehydrogenase was also found in 3-and 7-year-old re-vegetated grasslands compared with heavily degraded meadow. Our results suggest a significant positive impact of E. natans establishment on soil quality. Thus, E. natans establishment could be an effective and applicable measure in restoring heavily degraded alpine meadow in the region of Qinghai-Tibetan Plateau

Establishment of Elymus natans improves soil quality of a heavily degraded alpine meadow in Qinghai-Tibetan Plateau,

Abstract Elymus natans is a dominant native species widely planted to restore the heavily degraded alpine meadows in Qinghai-Tibetan plateau. The objective of this study was to determine how E. natans establishment affected the quality and fertility of a heavily degraded soil. Soil samples (at depths of 0-10, 10-20 and 20-30 cm) were collected from the 3-and 7-year-old E. natans re-vegetated grasslands, and in the heavily degraded alpine meadow (control). The establishment of E. natans promoted plant cover and aboveground biomass. Compared to the non-reseeded meadow, the concentration of total organic C increased by 13% in the soil under 3-year-old reseeded E. natans grassland at 0-10 cm, and by 7-33% in the soil under 7-year-old reseeded E. natans grassland at 0-10, 10-20 and 20-30 cm depths. Rapid increases in total and available N were also observed in two E. natans re-vegetated grasslands, especially in the 0-10 cm soil layer. Across three sampling depths, total P concentration was increased by 17-35% and 18-54% in 3-and 7-year-old reseeded soil respectively, compared to the soil of control. After 3 years of E. natans growth, microbial biomass C increased by 13-58% at 0-10 and 10-20 cm layers; while it increased by 43-87% in 7-year-old reseeded treatment at 0-10, 10-20 and 20-30 cm depths relative to control. A similar increasing trend was observed for microbial biomass N and P generally. Significant increase in neutral phosphatase, urease, catalase and dehydrogenase was also found in 3-and 7-year-old re-vegetated grasslands compared with heavily degraded meadow. Our results suggest a significant positive impact of E. natans establishment on soil quality. Thus, E. natans establishment could be an effective and applicable measure in restoring heavily degraded alpine meadow in the region of Qinghai-Tibetan Plateau

Characterization of the complete plastome of Elymus tangutorum (Poaceae: Triticeae)

Elymus tangutorum (Nevski) Handel-Mazzetti (Poaceae: Triticeae), a hexaploid perennial herb, is a kind of forage plant with large biomass. In this study, the complete plastome sequence of E. tangutorum was reported. The size of the plastome is 134,949 bp in length, including a large single copy region (LSC) of 80,556 bp, a small single copy region (SSC) of 12,767 bp, and a pair of inverted repeat (IR) regions with 20,813 bp. Moreover, a total of 131 functional genes were annotated, including 85 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. The maximum likelihood (ML) phylogenetic tree suggested that E. tangutorum was closely related to Elymus libanoticus and Dasypyrum villosum

Characterization and phylogenetic analysis of the complete chloroplast genome of <i>Asterothamnus centraliasiaticus</i> Novopokr. (Asteraceae: <i>Asterothamnus</i>)

Asterothamnus centraliasiaticus Novopokr., a species of perennial deciduous semi-shrub within the family Asteraceae, has excellent medical, economic, ecological and genetic value. In this study, the chloroplast genome of A. centraliasiaticus was first assembled using Illumina HiSeq2500 sequences. The results indicate that the complete cp genome of A. centraliasiaticus is 152,205 bp in length, and comprises a pair of inverted repeat (IR) regions of 25,031 bp each, a large single-copy (LSC) region of 83,956 bp and a small single-copy (SSC) region of 18,187 bp. The GC content of A. centraliasiaticus is 37.3%. A total of 130 genes were successfully annotated containing 85 protein-coding genes, 37 transfer RNA genes, and 8 ribosomal RNA genes. The maximum likelihood (ML) phylogenetic analysis based on the complete chloroplast genome data highly supported that A. centraliasiaticus was close to Aster lavandulifolius. These results will provide significant genetic information for the germplasm protection and reasonable development.</p

Fertilization can accelerate the pace of soil microbial community response to rest‐grazing duration in the three‐river source region of China

Abstract Overgrazing leads to grassland degradation and productivity decline. Rest‐grazing during the regreen‐up period can quickly restore grassland and fertilization is a common restoration strategy. However, the effects of rest‐grazing time and fertilization on soil microorganisms are unclear in the alpine grasslands. Therefore, the experiment of rest‐grazing time and fertilization was carried out to explore the response of soil microorganisms to rest‐grazing time and fertilization measures. A field control experiment with rest‐grazing time and fertilization as factors have been conducted from the time when grass returned to green till the livestock moved to the summer pasture in Dawu Town of Maqin County of China. The primary treatment we established was the five rest‐grazing time, including rest‐grazing time of 20 days, 30 days, 40 days, 50 days, and traditional grazing was used as a check group. At the same time, the secondary treatment was nitrogen addition of 300 kg·hm−2 in each primary treatment. The results showed that the total phospholipid fatty acid (total PLFA), actinomyces (Act), and arbuscular mycorrhizal fungi (AMF) showed an ever‐increasing biomass with the increase of rest‐grazing time and the highest was at 50 days of rest‐grazing, and they were all significantly higher than CK. In addition, soil microbial biomass carbon‐nitrogen ratio (MBC/MBN) had great influence on the change of microbial community. Applying nitrogen fertilizer can increase the maximum value of biomass of all PLFA groups and the biomass of all PLFA groups changed in an “inverted V” shape with the increase of rest‐grazing time. Besides, instead of MBC/MBN, NO3−‐N was positively correlated with the biomass of all PLFA groups, which actively regulated the trend of microbial functions. The longer rest‐grazing time is more conducive to the biomass of all PLFA groups. However, applying nitrogen fertilizer could break this pattern, namely, the 30 days rest‐grazing would be beneficial to the biomass of all PLFA groups. These findings provide key information that rest‐grazing during the regreen‐up period is benefiscial to the all PLFA groups and fertilization could change the response of microorganisms to rest‐grazing, which provide reference measures for the restoration of degraded alpine meadows

Proline Metabolism in Response to Climate Extremes in Hairgrass

Hairgrass (Deschampsia caespitosa), a widely distributed grass species considered promising in the ecological restoration of degraded grassland in the Qinghai-Xizang Plateau, is likely to be subjected to frequent drought and waterlogging stress due to ongoing climate change, further aggravating the degradation of grassland in this region. However, whether it would acclimate to water stresses resulting from extreme climates remains unknown. Proline accumulation is a crucial metabolic response of plants to challenging environmental conditions. This study aims to investigate the changes in proline accumulation and key enzymes in hairgrass shoot and root tissues in response to distinct climate extremes including moderate drought, moderate waterlogging, and dry–wet variations over 28 days using a completely randomized block design. The proline accumulation, contribution of the glutamate and ornithine pathways, and key enzyme activities related to proline metabolism in shoot and root tissues were examined. The results showed that water stress led to proline accumulation in both shoot and root tissues of hairgrass, highlighting the importance of this osmoprotectant in mitigating the effects of environmental challenges. The differential accumulation of proline in shoots compared to roots suggests a strategic allocation of resources by the plant to cope with osmotic stress. Enzymatic activities related to proline metabolism, such as Δ1-pyrroline-5-carboxylate synthetase, ornithine aminotransferase, Δ1-pyrroline-5-carboxylate reductase, Δ1-pyrroline-5-carboxylate dehydrogenase, and proline dehydrogenase, further emphasize the dynamic regulation of proline levels in hairgrass under water stress conditions. These findings support the potential for enhancing the stress resistance of hairgrass through the genetic manipulation of proline biosynthesis and catabolism pathways