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Energy balance and partitioning over grasslands on the Mongolian Plateau
No full textEnergy flux is a key component and driving factor in ecosystem processes and functions. Using 2015 datasets of eddy covariance, vegetation and meteorological measurements at four dominant ecosystems on the Mongolian Plateau, we analyzed the inter-site and seasonal variations and underlying biophysical controls on energy balance and partitioning in a meadow steppe (MDW), typical steppe (TPL), dry typical steppe (DRT) and shrubland (SHB). Vegetation dynamics dominated the energy partitioning. The growing season (May-Sept) net radiation (Rn) was 20% less at SHB due to higher bare soil coverage area than that at MDW. High vegetation cover and soil water content resulted in the highest latent heat (LE) at MDW, while sparse vegetation showed the highest sensible heat (H) at DRT among the four vegetation types. The Bowen ratios (beta, H/LE) at TPL (1.68), DRT (1.44) and SHB (1.44) were an order of magnitude higher than that at MDW (0.14). At DRT and SHB, beta had significantly negative feedback on canopy conductance (p < 0.05) and significantly positive feedback on vapor pressure deficit (VPD) (p < 0.05). We emphasized that the complex, interactive effects of vegetation types, ecosystem structures, and microclimate for the energy balance and partitioning
The Diversity Distribution and Climatic Niche of Samara Species in China
No full textStudying the distribution of samara species is of ecological and economic significance. This information helps us with understanding species dispersal mechanisms, evaluating the risk of invasive species, and the management of ecological forests. However, limited research has explored, on a large scale, the geographic distribution of samara species and their influential abiotic factors. Here, we use the distribution data of 835 vascular samara species and growth form data to explore their geographic patterns in China and the environmental determinants. We divided China into 984 grid cells and examined the relationship between the proportion of samara species and climate variables using both ordinary and spatial linear regressions for each grid cell. Total samara species richness is higher in southern China in low altitude regions and the proportion of woody samara species is significantly higher than that of herbaceous samara species. The proportion of woody samara species is higher in the northeast regions where precipitation is sufficient, winters are dry and mild, and temperature seasonality and land surface relief degree values are high. Annual precipitation and temperature seasonality are the most important climatic drivers for the distribution of woody samara species. In contrast, herbaceous samara species prefer to distribute to the areas where climate is warm and dry but have higher temperature seasonality. Temperature related variables (mean annual temperature, mean diurnal range, and temperature seasonality) are the most important drivers for the distribution of herbaceous samara species. Samara species can better adapt to climatic regions with large temperature fluctuations and dry winters. The present distribution patterns of samara species are formed by the combined adaptation of fruit traits and growth form to climate. This work contributes to predictions of the global distribution of samara species under future climate change scenarios and conservation and management for the samara species
Light-induced reversible reorganizations in closed Type II reaction centre complexes: physiological roles and physical mechanisms
No full textThe purpose of this review is to outline our understanding of the nature, mechanism and physiological significance of light-induced reversible reorganizations in closed Type II reaction centre (RC) complexes. In the so-called 'closed' state, purple bacterial RC (bRC) and photosystem II (PSII) RC complexes are incapable of generating additional stable charge separation. Yet, upon continued excitation they display well-discernible changes in their photophysical and photochemical parameters. Substantial stabilization of their charge-separated states has been thoroughly documented-uncovering light-induced reorganizations in closed RCs and revealing their physiological importance in gradually optimizing the operation of the photosynthetic machinery during the dark-to-light transition. A range of subtle light-induced conformational changes has indeed been detected experimentally in different laboratories using different bRC and PSII-containing preparations. In general, the presently available data strongly suggest similar structural dynamics of closed bRC and PSII RC complexes, and similar physical mechanisms, in which dielectric relaxation processes and structural memory effects of proteins are proposed to play important roles
Phylogenomic analyses based on the plastid genome and concatenated nrDNA sequence data reveal cytonuclear discordance in genus Atractylodes (Asteraceae: Carduoideae)
No full textAtractylodes species are widely distributed across East Asia and are cultivated as medicinal herbs in China, Japan, and Korea. Their unclear morphological characteristics and low levels of genetic divergence obscure the taxonomic relationships among these species. In this study, 24 plant samples were collected representing five species of Atractylodes located in China; of these, 23 belonged to members of the A. lancea complex. High-throughput sequencing was used to obtain the concatenated nrDNA sequences (18S-ITS1-5.8S-ITS2-28S) and plastid genomes. The concatenated nrDNA sequence lengths for all the Atractylodes species were 5,849 bp, and the GC content was 55%. The lengths of the whole plastid genome sequences ranged from 152,138 bp (A. chinensis) to 153,268 bp (A. lancea), while their insertion/deletion sites were mainly distributed in the intergenic regions. Furthermore, 33, 34, 36, 31, and 32 tandem repeat sequences, as well as 30, 30, 29, 30, and 30 SSR loci, were detected in A. chinensis, A. koreana, A. lancea, A. japonica, and A. macrocephala, respectively. In addition to these findings, a considerable number of heteroplasmic variations were detected in the plastid genomes, implying a complicated phylogenetic history for Atractylodes. The results of the phylogenetic analysis involving concatenated nrDNA sequences showed that A. lancea and A. japonica formed two separate clades, with A. chinensis and A. koreana constituting their sister clade, while A. lancea, A. koreana, A. chinensis, and A. japonica were found based on plastid datasets to represent a mixed clade on the phylogenetic tree. Phylogenetic network analysis suggested that A. lancea may have hybridized with the common ancestor of A. chinensis and A. japonica, while ABBA-BABA tests of SNPs in the plastid genomes showed that A. chinensis was more closely related to A. japonica than to A. lancea. This study reveals the extensive discordance and complexity of the relationships across the members of the A. lancea complex (A. lancea, A. chinensis, A. koreana, and A. japonica) according to cytonuclear genomic data; this may be caused by interspecific hybridization or gene introgression
Preseason heat requirement and days of precipitation jointly regulate plant phenological variations in Inner Mongolian grassland
No full textUnder global climate change, particularly warming, plant phenology may vary significantly thereby influencing a series of ecosystem functionalities. However, observational evidences of the variation of plant phenology and its association with climate change in temperate grassland are limited. In this study, we collated plant phenological records during the period from 1982 to 2019 at 26 sites in Inner Mongolian temperate grassland to elucidate the association of plant phenology with a series of environmental variables. The results showed that a trend of warming, particularly during May-September, occurred over the study period. However, this warming did not significantly influence plant phenology (e.g., green-up, flowering and brown-down) of four dominant plant species (i.e., Stipa, L. Chinensis, A. Cristatum and A. Frigida). Rather, multivariate regression considering a series of climatic and edaphic factors revealed that preseason climate predominantly regulates the dynamics of plant phenology. Specifically, heat requirement (HR) and days of precipitation (DOP) during the preseason were the two most influential controls on plant phenology. Our findings highlight the importance of incorporating precipitation as an additional predictor variable in current temperature-based phenology models for application in temperate grassland
Diodonopteris virgulata sp. nov., a climbing fern from the early Permian Wuda Tuff Flora and its paleoecology
No full textBotryopteridaceae, characterized by an omega-shaped foliar trace, is one of the best known late Paleozoic fern families with frequent occurrence in the Carboniferous of Euramerica and recent recognition in Permian deposits of Gondwana and Cathaysia. Diodonopteris is a recently established botryopterid genus based on coal-ball material from the lower Permian Taiyuan Formation of Shanxi Province, China. Here, a new species of Diodonopteris is described based on an anatomically preserved specimen from the well-known early Permian Wuda Tuff Flora in the Wuda Coalfield of Inner Mongolia, China. Diodonopteris virgulata sp. nov. is similar to the type species D. gracilis in the marginal position of protoxylem groups but differs from the latter in having a simpler cortex and a more expanded xylem strand. The two known Diodonopteris species share several characteristics considered ancestral among botryopterids, including strand shape, mode of pinna trace divergence, weak pinnule lamination, and a laminar wing on the rachis, as is consistent with Diodonopteris sitting outside any of the derived sublineages within Botryopteris. D. virgulata is confirmed to be a climber by direct preservation with the host. Moreover, the host plant is also evidenced to be a climber. The repeated preservation of the dual-climbing phenomenon in this swamp forest signals the complexity of early Permian ecosystems. (c) 2022 Published by Elsevier B.V
Biodiversity priority areas and conservation strategies for seed plants in China
No full textChina is known for its abundant plant resources, but biodiversity conservation faces unprecedented challenges. To provide feasible suggestions for sustainable conservation, we used the species richness algorithm and complementary algorithm to study distribution patterns of 34,082 seed plants based on 1,007,196 county-level distribution records. We reconstructed a phylogenetic tree for 95.35% of species and estimated the spatial phylogenetics, followed by correlation analyses between different distribution patterns. We identified 264 counties concentrated in southern and south-western mountainous areas as hotspots which covered 10% of the land area of China and harbored 85.22% of the Chinese seed plant species. The biodiversity conservation priorities we identified were highly representative as we have considered multiple conservation indicators. We evaluated the conservation effectiveness and gaps in the network of nature reserves and identified 31.44, 32.95, and 9.47%, respectively, of the hotspot counties as gaps in the national nature reserves, provincial nature reserves and both together, with respectively 55.77, 61.53, and 28.94% of the species. Analysis of the species composition showed there were a large number of threatened and endemic species occurring in the nature reserves' gaps. The conservation gaps need to be filled by establishing new nature reserves or national parks, especially in south-western China, and more attentions should be paid to strengthen the conservation of specific plant taxa due to the apparent mismatches between different distribution patterns
Target species rather than plant community tell the success of ecological restoration for degraded alpine meadows
No full textEcological conservation and restoration projects in Three-river Headwater Region (TRHR) have been implemented to respond to the serious degradation of alpine meadow ecosystem. Compared with the substantial amount of studies on the recovery of plant communities, soil quality and ecosystem services, few studies have focused on the restoration performance of target species. Therefore, we conducted this study to analyze the dynamics and underlying mechanisms of species richness and aboveground biomass of plant communities and target species. The results showed that restoration actions (grassland cultivation and fencing) did not significantly improve the community aboveground biomass of the degraded alpine meadows, while the actions did significantly promote community species richness, target species richness and target species aboveground biomass. Community species richness (20%-45%) was significantly impacted by the restoration strategies, and community aboveground biomass (31%-53%) was impacted by the mean annual precipitation and mean annual temperature. The species richness (57%) and aboveground biomass (63%) of the target species were directly and indirectly impacted by restoration actions, climatic factors, biotic factors and soil factors. The implications of this study stress that target species should be highlighted in assessing the restoration success of degraded alpine meadows. Integrating climatic factors, target species and other biotic and abiotic indicators could help us better understand and evaluate restoration actions for degraded alpine meadows in the TRHR or other similar regions worldwide
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
No full textThe 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 com-munity productivity and for establishing sustainable management practices of semi-arid grasslands under global change and land use scenarios.(c) 2021 Published by Elsevier B.V
The discovery of a key prenyltransferase gene assisted by a chromosome-level Epimedium pubescens genome
No full textEpimedium pubescens is a species of the family Berberidaceae in the basal eudicot lineage, and a main plant source for the traditional Chinese medicine Herba Epimedii. The current study achieved a chromosome-level genome assembly of E. pubescens with the genome size of 3.34 Gb, and the genome guided discovery of a key prenyltransferase (PT) in E. pubescens. Our comparative genomic analyses confirmed the absence of Whole Genome Triplication (WGT-gamma) event shared in core eudicots and further revealed the occurrence of an ancient Whole Genome Duplication (WGD) event approximately between 66 and 81 Million Years Ago (MYA). In addition, whole genome search approach was successfully applied to identify 19 potential flavonoid PT genes and an important flavonoid PT (EpPT8) was proven to be an enzyme for the biosynthesis of medicinal compounds, icaritin and its derivatives in E. pubescens. Therefore, our results not only provide a good reference genome to conduct further molecular biological studies in Epimedium genus, but also give important clues for synthetic biology and industrial production of related prenylated flavonoids in future