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Permafrost Degradation Diminishes Terrestrial Ecosystem Carbon Sequestration Capacity on the Qinghai-Tibetan Plateau
No full textEffects of permafrost degradation on carbon (C) and nitrogen (N) cycling on the Qinghai-Tibetan Plateau (QTP) have rarely been analyzed. This study used a revised process-based biogeochemical model to quantify the effects in the region during the 21st century. We found that permafrost degradation would expose 0.61 +/- 0.26 (mean +/- SD) and 1.50 +/- 0.15 Pg C of soil organic carbon under the representative concentration pathway (RCP) 4.5 and the RCP 8.5, respectively. Among them, more than 20% will be decomposed, enhancing heterotrophic respiration by 8.62 +/- 4.51 (RCP 4.5) and 33.66 +/- 14.03 (RCP 8.5) Tg C/yr in 2099. Deep soil N supply due to thawed permafrost is not accessible to plants, only stimulating net primary production by 7.15 +/- 4.83 (RCP 4.5) and 24.27 +/- 9.19 (RCP 8.5) Tg C/yr in 2099. As a result, the single effect of permafrost degradation would cumulatively weaken the regional C sink by 209.44 +/- 137.49 (RCP 4.5) and 371.06 +/- 151.70 (RCP 8.5) Tg C during 2020-2099. However, when factors of climate change, CO2 increasing and permafrost degradation are all considered, the permafrost region on the QTP would be a stronger C sink in the 21st century. Permafrost degradation has a greater influence on C balance of alpine meadows than alpine steppes on the QTP. The shallower active layer, higher soil C and N stocks, and wetter environment in alpine meadows are responsible for its stronger response to permafrost degradation. This study highlights that permafrost degradation could continue to release large amounts of C to the atmosphere irrespective of potentially more nitrogen available from deep soils
Divergent Drivers of Various Topsoil Phosphorus Fractions Across Tibetan Alpine Grasslands
No full textThe storage and dynamics of various soil phosphorus (P) fractions could determine soil P availability, and thus regulate terrestrial carbon cycle and its feedback to climate warming. However, little evidence is available about patterns and drivers of soil P fractions in alpine ecosystems which could play a crucial role in terrestrial carbon cycle. Here we evaluated various topsoil P fractions and their determinants in Tibetan alpine grasslands using systematic measurements along a 3,000 km transect. Our results showed that topsoil P concentrations in Tibetan alpine grasslands were higher or equivalent than those in temperate and tropical-subtropical ecosystems. Our results also revealed distinct drivers among various soil P fractions: microbial properties and soil pH were dominant drivers of labile P and secondary mineral P fractions, respectively. Mineral properties were key determinants of occluded P and organic P fractions, whereas primary mineral P fraction was largely predicted by precipitation and mineral properties. The large-scale evidence obtained in this study offers new insights for better predicting the trajectory of soil P availability and its interactions with ecosystem carbon cycle in alpine ecosystems under changing environment
Characterization of starch structures isolated from the grains of waxy, sweet, and hybrid sorghum (Sorghum bicolor L. Moench)
No full textIn this study, starches were isolated from inbred (sweet and waxy) and hybrid (sweet and waxy) sorghum grains. Structural and property differences between (inbred and hybrid) sweet and waxy sorghum starches were evaluated and discussed. The intermediate fraction and amylose content present in hybrid sweet starch were lower than those in inbred sweet starch, while the opposite trend occurred with waxy starch. Furthermore, there was a higher A chain (30.93-35.73% waxy, 13.73-31.81% sweet) and lower B-2 + B-3 chain (18.04-16.56% waxy, 24.07-17.43% sweet) of amylopectin in hybrid sorghum starch. X-ray diffraction (XRD) and Fourier transform infrared reflection measurements affirm the relative crystalline and ordered structures of both varieties as follows: inbred waxy > hybrid waxy > hybrid sweet > inbred sweet. Small angle X-ray scattering and C-13 CP/MAS nuclear magnetic resonance proved that the amylopectin content of waxy starch was positively correlated with lamellar ordering. In contrast, an opposite trend was observed in sweet sorghum starch due to its long B-2 + B-3 chain content. Furthermore, the relationship between starch granule structure and function was also concluded. These findings could provide a basic theory for the accurate application of existing sorghum varieties precisely
microRNAs and Their Roles in Plant Development
No full textSmall RNAs are short non-coding RNAs with a length ranging between 20 and 24 nucleotides. Of these, microRNAs (miRNAs) play a distinct role in plant development. miRNAs control target gene expression at the post-transcriptional level, either through direct cleavage or inhibition of translation. miRNAs participate in nearly all the developmental processes in plants, such as juvenile-to-adult transition, shoot apical meristem development, leaf morphogenesis, floral organ formation, and flowering time determination. This review summarizes the research progress in miRNA-mediated gene regulation and its role in plant development, to provide the basis for further in-depth exploration regarding the function of miRNAs and the elucidation of the molecular mechanism underlying the interaction of miRNAs and other pathways
Homogeneous selection is stronger for fungi in deeper peat than in shallow peat in the low-temperature fens of China
No full textPeatlands have accumulated enormous amounts of carbon over millennia, and climate changes threatens the release of this carbon into the atmosphere. Fungi are crucial drivers of global carbon cycling because they are the principal decomposer of organic matter in peatlands. However, the fungal community composition and ecological preferences in peat remain unclear, which restricts our ability to evaluate the role of the fungal community in peat biogeochemical functions. We investigated 54 soils from 6 low-temperature peatlands across China to fill this knowledge gap. The peat was divided into above-water table (AWT) and below-water table (BWT) layers based on the water table fluctuation. We investigated fungal community assembly processes and drivers for each peat layer. The results showed that fungal communities differed significantly among peat layers. The relative abundance of symbiotrophs was significantly higher in the AWT (17.4%) than in the BWT (9.0%), while the abundances of yeast and litter saprotrophs were obviously lower in the AWT than in the BWT. Our results revealed that the assemblage of both fungal taxonomic and phylogenetic communities was mainly governed by stochastic processes in both AWT (87.8%) and BWT (58.6%) layers. However, in the BWT, the relative importance of deterministic processes (28.4%) significantly increased, indicating a potential deterministic environmental selection induced by permanently anaerobic condition. Mean annual precipitation and mean annual temperature were the most critical drives for the assemblage of the fungal community in the BWT. These observations collectively indicate that fungal community assembly is depth-dependent, implying different community assembly mechanisms and ecological functions along the peat profile. These findings highlight the importance of climate driven deep peat fungal community composition assemblages and suggest the potential to project the changes in fungal diversity with ongoing climate change
Analysis of UAV lidar information loss and its influence on the estimation accuracy of structural and functional traits in a meadow steppe
No full textAccurate quantification of grassland structural and functional traits is the foundation for grassland management and restoration. Light detection and ranging (lidar), especially the unmanned aerial vehicle (UAV) lidar, has been recognized as an accurate and effective technique for local to regional-scale vegetation structural and functional traits estimation. However, in grassland ecosystems, it is more likely to be influenced by UAV lidar information loss caused by dense vegetation canopies. In this study, we investigated how UAV lidar information loss may occur and how it may influence the estimation accuracy of grassland structural and functional traits by comparing it with terrestrial laser scanning (TLS) and field measurements in a meadow steppe of northern China. Five structural traits (i.e., mean vegetation height, maximum vegetation height, standard deviation of vegetation height, canopy cover, and canopy volume) and one functional trait (i.e., aboveground biomass) were estimated from the UAV lidar data and TLS data for evaluation. The results showed that TLS-derived structural and functional traits had a much higher accuracy than UAV lidar-derived traits. By comparing with TLS data, we found that UAV lidar data had a much more prevailing information loss at canopy tops than at canopy bottoms. The average height loss of UAV lidar at canopy tops reached over 0.30 m, and the average relative height loss reached over 49%, comparing to a value of 0.03 m and 6% at canopy bottoms. Maximum vegetation height, standard deviation, and the distance from the UAV lidar system to the ground were the three most influential factors on UAV lidar information loss at canopy tops, indicating the commonly seen sharp canopy tops of grasslands were prone to be missed by the UAV lidar system. UAV lidar information loss at canopy tops had a much stronger influence on the estimation accuracy of grassland structural and functional traits than that at canopy bottoms. With the decrease of information loss at canopy tops, UAV lidar can be used to extract grassland structural and functional traits with a comparable accuracy to TLS. Among the five grassland traits, aboveground biomass was the least influenced by UAV lidar information loss. This study is a very first evaluation on the UAV lidar information loss in grassland ecosystems and its influence on grassland structural and functional trait estimation, which can provide guidance for UAV lidar data collection and processing in future grassland applications
Comprehensive analysis of climate-related comfort in southern China: Climatology, trend, and interannual variations
No full textThis study investigated the variations of climate-related comfort in Guangdong Province by using a comprehensive comfort index during 1970-2021. The results showed that (1) the comfortable period (extremely comfortable, comfortable, and relatively comfortable types) is distributed from October to the subsequent April, and the uncomfortable period (relatively uncomfortable and uncomfortable types) starts from May to September. The most dominant climate-related comfort in Guangdong is the relatively uncomfortable type. Spatially, more extremely comfortable and comfortable days appear in southeastern Guangdong. However, more relatively uncomfortable and uncomfortable days appear in southwestern Guangdong. (2) The linear trends of annual uncomfortable days in coastal regions are the most significant, which are attributed to increased surface air temperature (SAT) induced by the weakened summer monsoon. (3) Additionally, the extremely comfortable days in central and eastern Guangdong have negative correlations with the East Asian Winter Monsoon (EAWM). However, the uncomfortable days across Guangdong have positive correlations with the East Asian Summer Monsoon (EASM). The former connection is mainly caused by strong EAWM-induced low SAT, and the latter connection is mainly affected by strong EASM-induced less precipitation. Our results could provide some scientific references for urban planning, improvement of the thermal environment, and resident health risk analyses
N-glucosyltransferase GbNGT1 from ginkgo complements the auxin metabolic pathway (vol 8, 229, 2021)
No full textInsights into plant biodiversity conservation in large river valleys in China: A spatial analysis of species and phylogenetic diversity
No full textLarge river valleys (LRVs) are heterogeneous in habitat and rich in biodiversity, but they are largely overlooked in policies that prioritize conservation. Here, we aimed to identify plant diversity hotspots along LRVs based on species richness and spatial phylogenetics, evaluate current conservation effectiveness, determine gaps in the conservation networks, and offer suggestions for prioritizing conservation. We divided the study region into 50 km x 50 km grid cells and determined the distribution patterns of seed plants by studying 124,927 occurrence points belonging to 14,481 species, using different algorithms. We generated phylogenies for the plants using the V. PhyloMaker R package, determined spatial phylogenetics, and conducted correlation analyses between different distribution patterns and spatial phylogenetics. We evaluated the effectiveness of current conservation practices and discovered gaps of hotspots within the conservation networks. In the process, we identified 36 grid cells as hotspots (covering 10% of the total area) that contained 83.4% of the species. Fifty-eight percent of the hotspot area falls under the protection of national nature reserves (NNRs) and 83% falls under national and provincial nature reserves (NRs), with 42% of the area identified as conservation gaps of NNRs and 17% of the area as gaps of NRs. The hotspots contained high proportions of endemic and threatened species, as did conservation gaps. Therefore, it is necessary to optimize the layout of current conservation networks, establish micro-nature reserves, conduct targeted conservation priority planning focused on specific plant groups, and promote conservation awareness. Our results show that the conservation of three hotspots in Southwest China, in particular, is likely to positively affect the protection of biodiversity in the LRVs, especially with the participation of the neighboring countries, India, Myanmar, and Laos
Driving mechanisms of climate-plant-soil patterns on the structure and function of different grasslands along environmental gradients in Tibetan and Inner Mongolian Plateaus in China
No full textGrassland plants contribute to carbon fixation through photosynthesis, which can in turn produce plant biomass. Previous studies have demonstrated that vegetation productivity is enhanced by improved soil nutrient status in humid environments and is influenced by climate in arid environments. However, the responses of biomass productivity to different patterns of climate-plant-soil in different natural grassland ecosystems have not been clearly and comprehensively analyzed. In this study, we systematically explore the functional patterns of different grasslands, as well as the underlying mechanisms in the response to key climatic, soil, and plant factors. The survey range covered broad environmental gradients from humid, semi-arid, to arid environments in Tibetan and Inner Mongolian Plateaus. We found that the above-and belowground biomass production gradually decreased from humid, semi-arid, to arid environments. Biomass production was sensitive to climatic factors in different environments. However, compared to soil and plant factors, climate was always the most important factor determining biomass production in all grassland types. Furthermore, biomass production was regulated mainly by climate and soil characteristics in humid environments, but by climate in arid environments. Spe-cifically, the corresponding limiting factors of each factor largely dominated the effects of the corresponding factors on different grasslands. For instance, the climate dominated by temperature negatively influenced the soil nutrient availability and then influenced the aboveground biomass production in alpine humid grasslands. These findings enhance our understanding of the heterogeneity of mechanisms of different grasslands along broad environmental gradients, which are crucial for predicting the effects and consequences of environmental change on terrestrial ecosystem functioning