Unexpected Diversity in Ecosystem Nutrient Responses to Experimental Drought in Temperate Grasslands

The responses of ecosystem nitrogen (N) and phosphorus (P) to drought are an important component of globalchange studies. However, previous studies were more often based on site-specific experiments, introducing a significantuncertainty to synthesis and site comparisons. We investigated the responses of vegetation and soil nutrientsto drought using a network experiment of temperate grasslands in Northern China. Drought treatment (66%reduction in growing season precipitation) was imposed by erecting rainout shelters, respectively, at the driest,intermediate, and wettest sites. We found that vegetation nutrient concentrations increased but soil nutrient concentrationsdecreased along the aridity gradient. Differential responses were observed under experimentaldrought among the three grassland sites. Specifically, the experimental drought did not change vegetation andsoil nutrient status at the driest site, while strongly reduced vegetation but increased soil nutrient concentrationsat the site with intermediate precipitation. On the contrary, experimental drought increased vegetation N concentrationsbut did not change vegetation P and soil nutrient concentrations at the wettest site. In general, the differentialeffects of drought on ecosystem nutrients were observed between manipulative and observationalexperiments as well as between sites. Our research findings suggest that conducting large-scale, consistent, andcontrolled network experiments is essential to accurately evaluate the effects of global climate change on terrestrialecosystem bio-geochemistry.

Degradation significantly decreased the ecosystem multifunctionality of three alpine grasslands: evidences from a large-scale survey on the Qinghai-Tibetan Plateau

Owing to the joint effects of ecosystem fragility,anthropogenic disturbance and climate change,alpine grasslands(alpine meadow,alpine steppe and alpine desert)have experienced serious degradation during the past several decades.Grasslands degradation has severely affected the delivery of ecosystem multifunctionality(EMF)and services,and then threatens the livelihood of local herdsmen and ecological security of China.However,we still lack comprehensive insights about the effects of degradation and climatic factors on EMF of alpine grasslands,especially for alpine desert ecosystem.Therefore,we applied a large-scale field investigation to answer this question.Our results suggested grassland degradation significantly decreased the belowground ecosystem multifunctionality(BEMF)and EMF of alpine grasslands and aboveground ecosystem multifunctionality(AEMF)of alpine meadow,while did not reduce the AEMF of alpine steppe and desert.Except for the insignificant difference between degraded steppe and degraded desert in AEMF,the alpine meadow showed the highest AEMF,BEMF and EMF,alpine steppe ranked the second and alpine desert was the lowest.AEMF,BEMF and EMF of health alpine grasslands were strongly affected by mean annual precipitation(MAP)(19%-51%)and mean annual temperature(MAT)(9%-36%),while those of degraded meadow and degraded desert were not impacted by precipitation and temperature.AEMF and BEMF showed a synergistic relationship in healthy alpine grasslands(12%-28%),but not in degraded grasslands.Our findings emphasized the urgency of implementing the feasible ecological restoration project to mitigate the negative influences of grassland degradation on EMF of alpine ecosystems.

Can Digital Intelligence and Cyber-Physical-Social Systems Achieve Global Food Security and Sustainability?

Plants sequester carbon through photosynthesis and provide primary productivity for the ecosystem. However, they also simultaneously consume water through transpiration, leading to a carbon-water balance relationship. Agricultural production can be regarded as a form of carbon sequestration behavior.From the perspective of the natural-social-economic complex ecosystem, excessive water usage in food production will aggravate regional water pressure for both domestic and industrial purposes. Hence, achieving a harmonious equilibrium between carbon and water resources during the food production process is a key scientific challenge for ensuring food security and sustainability. Digital intelligence(DI) and cyber-physical-social systems(CPSS) are emerging as the new research paradigms that are causing a substantial shift in the conventional thinking and methodologies across various scientific fields, including ecological science and sustainability studies. This paper outlines our recent efforts in using advanced technologies such as big data, artificial intelligence(AI), digital twins, metaverses, and parallel intelligence to model, analyze, and manage the intricate dynamics and equilibrium among plants, carbon, and water in arid and semiarid ecosystems. It introduces the concept of the carbon-water balance and explores its management at three levels: the individual plant level, the community level, and the natural-social-economic complex ecosystem level. Additionally, we elucidate the significance of agricultural foundation models as fundamental technologies within this context. A case analysis of water usage shows that, given the limited availability of water resources in the context of the carbon-water balance, regional collaboration and optimized allocation have the potential to enhance the utilization efficiency of water resources in the river basin. A suggested approach is to consider the river basin as a unified entity and coordinate the relationship between the upstream, midstream and downstream areas. Furthermore, establishing mechanisms for water resource transfer and trade among different industries can be instrumental in maximizing the benefits derived from water resources.Finally, we envisage a future of agriculture characterized by the integration of digital, robotic and biological farming techniques.This vision aims to incorporate small tasks, big models, and deep intelligence into the regular ecological practices of intelligent agriculture.

Revitalizing the grassland on the Qinghai–Tibetan Plateau

Grassland is the largest ecosystem on the Qinghai–Tibetan Plateau(QTP)and provides multiple ecosystem functions and services.Understanding the endowment of the QTP grassland and how to revitalize it have profound implications for the sustainable use and efficient conservation of these unique and globally valuable ecosystems.In this paper,we highlight the importance of the QTP grassland in regional and global settings,stress the values of the QTP grassland in ecological and socioeconomic dimensions,and emphasize the actions needed to restore degraded grassland in the QTP region.The QTP is the largest single area of alpine grassland in the world and an important gene pool of alpine biological resources.The QTP grassland covers two critical ecoregions for conserving the best and most representative habitats for alpine biodiversity on the planet.The QTP grassland is also regarded as one of the best carriers and objects of socio-ecological systems in the world.To promote the resilience and sustainability of the QTP grassland through adaptation,different parties need to work together tofind feasible options to resist shock,stresses,and disturbance and to maintain the fundamental functions and basic structures of the QTP grassland.

Genome Assembly of Alfalfa Cultivar Zhongmu-4 and Identification of SNPs Associated with Agronomic Traits

Alfalfa(Medicago sativa L.)is the most important legume forage crop worldwide with high nutritional value and yield.For a long time,the breeding of alfalfa was hampered by lacking reliable information on the autotetraploid genome and molecular markers linked to important agronomic traits.We herein reported the de novo assembly of the allele-aware chromosome-level genome of Zhongmu-4,a cultivar widely cultivated in China,and a comprehensive database of genomic variations based on resequencing of 220 germplasms.Approximate 2.74 Gb contigs(N50 of 2.06 Mb),accounting for 88.39%of the estimated genome,were assembled,and 2.56 Gb contigs were anchored to 32 pseudo-chromosomes.A total of 34,922 allelic genes were identified from the allele-aware genome.We observed the expansion of gene families,especially those related to the nitrogen metabolism,and the increase of repetitive elements including transposable elements,which probably resulted in the increase of Zhongmu-4 genome compared with Medicago truncatula.Population structure analysis revealed that the accessions from Asia and South America had relatively lower genetic diversity than those from Europe,suggesting that geography may influence alfalfa genetic divergence during local adaption.Genome-wide association studies identified 101 single nucleotide polymorphisms(SNPs)associated with 27 agronomic traits.Two candidate genes were predicted to be correlated with fall dormancy and salt response.We believe that the alleleaware chromosome-level genome sequence of Zhongmu-4 combined with the resequencing data of the diverse alfalfa germplasms will facilitate genetic research and genomics-assisted breeding in variety improvement of alfalfa.

Excessive plant compensatory growth:a potential endogenous driver of meadow degradation on the Qinghai-Tibetan Plateau

Degradation of meadow ecosystems in the largest alpine region of the world,i.e.,the Qinghai-Tibetan Plateau(QTP),is a crucial ecological issue that has ardently discussed in recent years.Many factors,such as livestock overgrazing,climate change and overpopulation of small mammals are treated as important factors that cause the degradation of meadow ecosystems in the QTP.However,there are few hypotheses focus on the potential role of plant compensatory growth on meadow degradation.We proposed a compensatory growth-related hypothesis to understand the potential degradation process of meadow ecosystems in the QTP.We discussed that there are two stages of meadow degradation,i.e.the beginning stage of meadow degradation that is triggered by high-strength overcompensation;and the intensification stage of meadow degradation,which are driven by external factors such as climate warming,small mammals and thawing of permafrost.The mechanism of meadow degradation driven by plant compensatory growth is the asynchronism of plant consumption and the availability of soil nutrients.Our hypothesis that plant compensatory growth drives meadow degradation under the overgrazing condition requires re-examination and modification by testing the balance between soil nutrient cycling rates and the strength of plant compensatory growth in alpine regions.

Trichoderma metabolites trigger aggregation behavior in Formosan subterranean termites (Coptotermes formosanus)

Our previous studies have shown that some Trichoderma fungi trigger aggregation behavior in Formosan subterranean termites,Coptotermes formosanus Shiraki.However,the mechanisms underlying the induction of termite aggregation by Trichoderma fungi remain unclear.Here,we found that the aqueous or acetone extract of Trichoderma asperellum Samuels,Lieckfeldt&Nirenberg and Trichoderma virens Pers.ex Fries isolated from the gut or cuticle of C.formosanus elicited significant termite aggregation in 2-choice tests.We then screened 9 Trichoderma metabolites(3-acetoxy-2-butanone,phenol,3-ethoxypropionic acid,ethyl 2,4-dioxovalerate,diglycolic acid,d-valine,styrene,3-aminopyridine,and hexyl acetoacetate)that triggered termite aggregation.Among them,phenol(1000μg/mL),3-ethoxypropionic acid(10μg/mL),ethyl 2,4-dioxovalerate(1000μg/mL),and diglycolic acid(1000μg/mL)showed the strongest activities,triggering termite aggregation throughout the 24-h period.As T.asperellum and T.virens produce different metabolites that trigger aggregation behavior in termites,the mechanisms underlying the interaction between subterranean termites and Trichoderma fungi likely vary.Future studies are needed to test whether these chemicals can attract termites and increase bait consumption.

青藏高原植被结构变化反映环境变迁

草地植被结构对于其生产和生态功能至关重要,但大尺度信息严重匮乏.本研究结合多源遥感数据和深度学习,在区域尺度上厘清了青藏高原高寒草地基于群系的植物群落结构空间格局,并比较了其历史变化.过去40年,高寒草甸在高寒草地中的比例从50%上升到69%,反映了变暖变湿的环境变化.此外,高寒草甸和高寒草原中高山嵩草草甸和紫花针茅草原的优势度分别增强到76%和92%.其中,气候因子驱动了紫花针茅草原近些年的分布;高山嵩草草甸近些年的分布则并非完全由气候驱动,人类活动可能起重要作用.本研究首次探索了区域尺度植被结构特征与历史变化,为认识青藏高原草地变化的驱动力及其空间异质性提供了新视角.

植物多样性而非其土壤遗留效应影响外来植物入侵

植物多样性可以影响外来植物入侵,然而植物多样性的土壤遗留效应是否能够影响外来植物入侵目前仍不清楚。植物多样性能够改变土壤微生物群落和土壤理化性质,这种遗留效应可能会对该土壤中外来植物的生长产生影响。因此,我们假设植物多样性的土壤遗留效应会影响外来植物的入侵。为了检验该假说,我们开展了一个两阶段的植物-土壤反馈实验。在土壤驯化阶段,我们将12个植物物种(4种禾草植物、3种豆科植物和5种杂类草植物)分别单独种植,或者随机选择8个物种(包含3个功能型)混合种植在土壤中。在反馈阶段,我们将入侵植物三叶鬼针草(Bidens pilosa)分别与本地禾草荩草(Arthraxon hispidus)、本地杂类草翅果菊(Pterocypsela indica)或者同时与荩草和翅果菊种植在被驯化过的土壤中。研究结果显示,三叶鬼针草相对于其本地竞争植物的生长取决于驯化植物和竞争植物物种的功能型。驯化植物的多样性对三叶鬼针草与其本地竞争植物之间的生长差异没有显著影响。然而,随着本地竞争植物物种多样性的增加,三叶鬼针草相对于其本地竞争植物的生长显著降低。这些结果表明,当前的植物多样性可以通过增加入侵植物和本地植物之间的生长不平衡性来减少外来植物的入侵。但是,植物多样性的土壤遗留效应对外来植物入侵的影响可能很小。

氮添加对内蒙古草原植物地上和地下碳氮磷化学计量学特征的影响

氮沉降对生态系统功能和过程具有显著影响。已有研究表明氮添加会影响植物叶片C:N:P化学计量特征。然而,氮添加对植物根系C:N:P化学计量特征影响的研究罕有报道。本论文的主要目的是对比氮添加对草原植物群落地上和地下C:N:P化学计量特征的影响。我们在内蒙古锡林郭勒草原开展了一个7年的氮添加实验,该实验包括6个处理,分别是对照:control;N1:0.4 mol·m-2 N;N2:0.8 mol·m^(-2) N;N3:1.6 mol·m^(-2) N;N4:2.8 mol·m^(-2) N;N5:4 mol·m^(-2) N,每个处理6次重复。我们测量并分析了植物地上、地下生物量和C:N:P化学计量特征。研究结果表明,氮添加会导致植物群落地上部分碳浓度降低,氮浓度和磷浓度升高,C:N和C:P比值降低,N:P升高,而且地上碳、氮、磷库均因施氮而增加。然而,氮添加对0-10,10-30,30-50和50-100 cm 4个土层的地下部分碳、氮、磷浓度、比例、库和化学计量特征没有显著影响。综上所述,氮添加会显著改变植物群落地上部分C:N:P化学计量特征,进而影响草地生态系统的功能和过程,但对地下C:N:P化学计量特征几乎没有影响。

Overlooked uneven progress across sustainable development goals at the global scale: Challenges and opportunities

Differences in progress across sustainable development goals(SDGs)are widespread globally;meanwhile,the rising call for prioritizing specific SDGs may exacerbate such gaps.Nevertheless,how these progress differences would influence global sustainable development has been long neglected.Here,we present the first quantitative assessment of SDGs’progress differences globally by adopting the SDGs progress evenness index.Our results highlight that the uneven progress across SDGs has been a hindrance to sustainable development because(1)it is strongly associated with many public health risks(e.g.,air pollution),social inequalities(e.g.,gender inequality,modern slavery,wealth gap),and a reduction in life expectancy;(2)it is also associated with deforestation and habitat loss in terrestrial and marine ecosystems,increasing the challenges related to biodiversity conservation;(3)most countries with low average SDGs performance show lower progress evenness,which further hinders their fulfillment of SDGs;and(4)many countries with high average SDGs performance also showcase stagnation or even retrogression in progress evenness,which is partly ascribed to the antagonism between climate actions and other goals.These findings highlight that while setting SDGs priorities may be more realistic under the constraints of multiple global stressors,caution must be exercised to avoid new problems from intensifying uneven progress across goals.Moreover,our study reveals that the urgent needs regarding SDGs of different regions seem complementary,emphasizing that regional collaborations(e.g.,demand-oriented carbon trading between SDGs poorly performed and well-performed countries)may promote sustainable development achievements at the global scale.