Changes in the Phylogenetic Structure of Alpine Grassland Plant Communities on the Qinghai-Tibetan Plateau with Long-Term Nitrogen Deposition.

Nitrogen (N) deposition rates have notably increased around the world, especially in high-altitude regions like the Qinghai-Tibetan Plateau (QTP). We conducted a six-year comprehensive experiment to simulate nitrogen deposition in an alpine grassland area near Qinghai Lake. Four levels of nitrogen depositions, i.e., 0 (CK), 8 kg N ha-1year-1 (N1), 40 kg N ha-1year-1 (N2), and 72 kg N ha-1year-1 (N3), with three replicates for each N treatment, were tested annually in early May and early July, with the meticulous collection of plant and soil samples during the peak growth period from 15 July to 15 August. We used the null model to evaluate the impact of environmental filtration and interspecific competition on the dynamics of the plant community was assessed based on the level of discrete species affinities within the plant community by constructing a phylogenetic tree. The results showed that the environmental filter was the predominant driver for the change of community's genealogical fabric. The N2 and N3 treatments increased the influence of soil factors on the change of plant community structure. Climatic factors played a crucial role on the change of plant community in the CK grassland area, while soil factors were dominant in the N1- and N3-treated grasslands.

Growth and physiological metabolic regulation mechanisms of the dominant plant Leymus secalinus in alpine meadow under nitrogen deposition.

Nitrogen (N) deposition is an important pathway that affects the growth and development of alpine grassland plants. Under N deposition, Leymus secalinus has become the most dominant species in the alpine meadow of the Qinghai-Tibetan Plateau. However, its adaptive mechanisms to N deposition are still unknown. Therefore, we analyzed the physiological indices of Leymus secalinus under different N deposition levels (CK, 0 kg N ha-1 yr-1; N1, 8 kg N ha-1 yr-1; N3, 40 kg N ha-1 yr-1; N5, 72 kg N ha-1 yr-1) and focused on its growth and metabolism. The results indicated that the leaf carbon (C), N, amino acid (AA), and photosynthetic pigment contents in Leymus secalinus were significantly increased under N deposition, its endogenous hormone levels were regulated and the activities of N metabolism-related enzymes were enhanced. Metabolomics analysis further showed that the metabolites changed significantly and were mostly enriched in the amino acid metabolic pathway. Among them, glutamine and aspartic acid played key roles in N deposition for dominant growth of Leymus secalinus by regulating N and amino acid metabolism. These analyses unveiled the physiological and biochemical changes of dominant species in response to N deposition, identifying critical metabolites involved in this process. Furthermore, these findings provide substantial evidence explaining the ecological phenomenon of Leymus secalinus emerging as a dominant species under N deposition, serving as a data reference for understanding the physiological response and adaptation to N deposition in alpine grassland plants.

Long-term grazing reduces soil fungal network complexity but enhances plant-soil microbe network connectivity in a semi-arid grassland.

Grazing plays a significant role in shaping both aboveground vegetation and belowground microbial communities in arid and semi-arid grasslands, which in turn affects ecosystem functions and sustainability. Therefore, it was essential to implement effective grazing management practices to preserve ecological balance and support sustainable development in these delicate environments. To optimize the traditional continuous grazing policy, we conducted a 10-year seasonal grazing experiment with five treatments in a typical grassland in northern China: no grazing (NG), continuous summer grazing (CG), and three seasonal grazing treatments (G57 in May and July, G68 in June and August, and G79 in July and September). Our study found that although grazing reduced plant community biomass, G68 treatment maintained high plant height and community diversity (P < 0.05). Grazing did not affect soil bacterial and archaeal alpha diversity, but CG treatment reduced soil fungal diversity (P < 0.05). CG reduced the archaeal network's vertices (which represent microbial taxa, OTUs) and connections (ecological interactions between taxa), but seasonal grazing increased its complexity. Furthermore, grazing did not change bacterial networks but enhanced cross-domain interactions (relationships between different biological groups) of plant-soil fungi and plant-soil archaea. Overall, we used the Mantel test to find that soil microbial diversity was positively correlated with soil physicochemical properties rather than plant community characteristics after grazing. These findings are beneficial for the optimization of sustainable grassland management policies and the protection of plant and soil biodiversity.

Different responses of individuals, functional groups and plant communities in CSR strategies to nitrogen deposition in high-altitude grasslands.

The Competitor, Stress Tolerator, and Ruderal (CSR) theory delineates the ecological strategies of plant species. Nevertheless, how these ecological strategies shift at the levels of individuals, functional groups and plant communities to cope with increasing nitrogen deposition remains unclear. In this study, simulated nitrogen deposition experiments were performed in high-altitude grasslands of alpine meadows and alpine steppe on the Qinghai-Tibetan Plateau (QTP) by employing the strategy and functional type framework (StrateFy) methodology to evaluate plant CSR strategies. Our results indicated that the dominant ecological strategy of the high-altitude grassland on the QTP were predominantly aligned with the R-strategy. In both alpine meadow and alpine steppe grasslands, the community-weighted mean (CWM) of C scores were increased with nitrogen addition, while CWM of R and S scores were not significantly correlated with nitrogen addition. Remarkably, the increase in C scores due to nitrogen enrichment was observed solely in non-legumes, suggesting an enhanced competitive capability of non-legumes in anticipation of future nitrogen deposition. Leymus secalinus was dominated in both alpine meadow and alpine steppe grasslands across all levels of nitrogen deposition, with increasing C scores along the nitrogen gradients. Furthermore, the sensitivity of C scores of individual plant, functional group and plant community to nitrogen deposition rates was more pronounced in alpine steppe grassland than in alpine meadow grassland. These findings furnish novel insights into the alterations of ecological strategies in high-altitude alpine grasslands on the QTP and similar regions worldwide in cope with escalating nitrogen deposition.

Does bumblebee preference of continuous over interrupted strings in string-pulling tasks indicate means-end comprehension?

Bumblebees (Bombus terrestris) have been shown to engage in string-pulling behavior to access rewards. The objective of this study was to elucidate whether bumblebees display means-end comprehension in a string-pulling task. We presented bumblebees with two options: one where a string was connected to an artificial flower containing a reward and the other presenting an interrupted string. Bumblebees displayed a consistent preference for pulling connected strings over interrupted ones after training with a stepwise pulling technique. When exposed to novel string colors, bees continued to exhibit a bias towards pulling the connected string. This suggests that bumblebees engage in featural generalization of the visual display of the string connected to the flower in this task. If the view of the string connected to the flower was restricted during the training phase, the proportion of bumblebees choosing the connected strings significantly decreased. Similarly, when the bumblebees were confronted with coiled connected strings during the testing phase, they failed to identify and reject the interrupted strings. This finding underscores the significance of visual consistency in enabling the bumblebees to perform the task successfully. Our results suggest that bumblebees' ability to distinguish between continuous strings and interrupted strings relies on a combination of image matching and associative learning, rather than means-end understanding. These insights contribute to a deeper understanding of the cognitive processes employed by bumblebees when tackling complex spatial tasks.

Independent Risk Factors Associated With Venous Thromboembolism After Knee Arthroscopy: A Retrospective Study of 222 Patients.

Background: A serious complication after knee arthroscopy is venous thromboembolism (VTE), which includes both deep vein thrombosis (DVT) and pulmonary embolism (PE). However, asymptomatic VTE is frequently undetected. Purpose: To (1) report the incidence of VTE after knee arthroscopy using ultrasound examination and computed tomography pulmonary angiography (CTPA) and (2) discover the independent risk factors of VTE after knee arthroscopy and determine the corresponding cutoff values of these indicators. Study Design: Case-control study; Level of evidence, 3. Methods: Included were 222 patients (115 male) who underwent arthroscopic knee procedures between October 2022 and January 2023. Baseline characteristics, blood test results, and VTE assessments were collected. During the 2-week follow-up, routine lower extremity vascular ultrasound was applied for DVT measurement, with CTPA evaluation for suspected PE. Patients were allocated into VTE and no-VTE groups, and descriptive statistics were used to analyze baseline data. Logistic regression analysis was used to determine the correlation between binary variables and the presence of postoperative VTE. Multivariate logistic regression analysis was further performed to determine the independent risk factors of VTE. Results: Of the 222 patients, 37 (16.7%) had DVT and 1 (0.5%) had both DVT and PE. Compared to the no-VTE group, the VTE group was significantly older, with more female patients; higher body mass index (BMI) and postoperative D-dimer level; and higher rates of hypertension, hyperlipidemia, varicose veins of the lower extremity, and abnormal postoperative fibrin degradation product level (P≤ .043 for all). Notably, operative time >20 minutes was not significantly associated with postoperative VTE (P = .513). The independent risk factors for VTE included age >32 years (odds ratio [OR], 20.71 [95% CI, 4.40-97.47]; P < .001), BMI >23 kg/m2 (OR, 3.52 [95% CI, 1.11-11.14]; P = .032), hyperlipidemia (OR, 6.81 [95% CI, 1.86-24.88]; P = .004), and postoperative D-dimer level >0.63 mg/L (OR, 34.01 [95% CI, 7.36-157.07]; P < .001). Conclusion: The incidence of VTE after knee arthroscopy was 16.7% at the 2-week follow-up. Age >32 years, BMI >23 kg/m2, hyperlipidemia, and postoperative D-dimer >0.63 mg/L were independent risk factors of postoperative VTE within 2 weeks after knee arthroscopy. For patients with knee arthroscopy, the cutoff value of postoperative D-dimer for VTE was found to be 0.63 mg/L for timely intervention.

Spatial distribution and drivers of arbuscular mycorrhizal fungi on the Tibetan Plateau.

Introduction: Arbuscular mycorrhizal fungi (AMF) are pivotal in plant resource acquisition, mediating plant interactions, and influencing soil carbon dynamics. However, their biogeographical distribution in Tibetan alpine grasslands remains understudied. Methods: In this research, we examined the distribution pattern of AMF communities and their key determinants along a 2000-km transect across the Tibetan plateau, encompassing 7 alpine meadows and 8 alpine steppes. Results: Our findings indicate that AMF community diversity and composition exhibit similarities between alpine meadows and alpine steppes, primarily influenced by latitude and evapotranspiration. At the genus level, Glomus predominated in both alpine meadow (36.49%±2.67%) and alpine steppe (41.87%±2.36%) soils, followed by Paraglomus (27.14%±3.69%, 32.34%±3.28%). Furthermore, a significant decay relationship of AMF community was observed over geographical distance. Null model analyses revealed that random processes predominantly (>50%) drove the assembly of AMF communities. Discussion: In summary, our study elucidates the spatial distribution pattern of AMF in Tibetan plateau grasslands and underscores the significant influence of geographical and climatic factors on AMF community dynamics.

Intra-Articular Platelet-Rich Plasma Injection After Anterior Cruciate Ligament Reconstruction: A Randomized Clinical Trial.

Importance: Platelet-rich plasma (PRP) has been considered a promising treatment for musculoskeletal disorders. The effects of PRP on clinical outcomes of anterior cruciate ligament reconstruction (ACLR) are controversial. Objective: To compare subjective outcomes and graft maturity in patients undergoing ACLR with and without postoperative intra-articular PRP injection. Design, Setting, and Participants: This surgeon- and investigator-masked randomized clinical trial included patients treated at a national medical center in China who were aged 16 to 45 years and scheduled to undergo ACLR. Participants were enrolled between March 21, 2021, and August 18, 2022, and followed up for 12 months, with the last participant completing follow-up on August 28, 2023. Interventions: Participants were randomized 1:1 to the PRP group (n = 60), which received 3 doses of postoperative intra-articular PRP injection at monthly intervals, or to the control group (n = 60), which did not receive postoperative PRP injection. Both groups had the same follow-up schedule. Main Outcomes and Measures: The primary outcome was the mean score for 4 subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS4) (range, 0-100, with higher scores indicating better knee function and fewer symptoms) at 12 months postoperatively. Secondary outcomes were patient-reported outcomes, graft maturity (on magnetic resonance imaging), and physical examinations at 3, 6, and 12 months. Results: Among the 120 randomized participants (mean [SD] age, 29.0 [8.0] years; 84 males [70%]), 114 (95%) were available for the primary outcome analysis. The mean KOOS4 scores at 12 months were 78.3 (SD, 12.0; 95% CI, 75.2-81.4) in the PRP group and 76.8 (SD, 11.9; 95% CI, 73.7-79.9) in the control group (adjusted mean between-group difference, 2.0; 95% CI, -2.3 to 6.3; P = .36). Secondary outcomes were not statistically significantly different between the 2 groups except for sports and recreation level and graft maturity at 6 months. Intervention-related adverse events included pain at the injection site and knee swelling after injection. Conclusions and Relevance: In this randomized clinical trial among patients undergoing ACLR, the addition of postoperative intra-articular PRP injection did not result in superior improvement of knee symptoms and function at 12 months compared with no postoperative injection. Further studies are required to determine appropriate indications for PRP in musculoskeletal disorders. Trial Registration: Chinese Clinical Trial Registry Identifier: ChiCTR2000040262.

Response of species dominance and niche of plant community to wetland degradation along alpine lake riparian.

Alpine wetland degradation threatens riparian biodiversity and ecological balance. Our study, conducted in July 2020 along the northern and eastern shores of Qinghai Lake, seeks to unravel the impacts of such degradation on plant species dominance and ecological niches, using advanced network analysis methods to explore the dynamics and survival strategies of plant species. We applied a space-to-time method to delineate three wetland degradation stage: a healthy swamp wetland, a slightly degraded wet meadow, and a degraded dry meadow. Six representative sampling points were chosen. At each point, three sample lines were randomly established, radiating outward from the center of the lake wetland, with each stage of degradation meticulously examined through three replicates to assess the plant communities in terms of species composition, plant height, coverage, and abundance. The results indicated: Species such as Kobresia tibetica and Leymus secalinus exhibit remarkable abundance across various stages of wetland degradation, indicating a robust tolerance to these conditions. This observation, coupled with the complexity of plant community structures in degrading wetlands, suggests that such intricacy cannot be solely attributed to the dominance of particular species. Instead, it is the result of a diverse array of species adapting to fluctuating water levels, which promotes increased species richness. Despite the prominence of species that exhibit rapid growth and reproduction, the ecological significance of less abundant species in contributing to the community's complexity is also notable. Changes in habitat conditions due to wetland degradation facilitate both competitive and cooperative interactions among species, highlighting the dynamic nature of these ecosystems. Our analysis shows no significant linear relationship between the ecological niche overlap values and niche widths of plant species. However, the strategies employed by dominant species for competition and resource acquisition, as observed in the ecological niche overlap networks, underscore the adaptive capacity of plant communities. These insights underscore the need for tailored restoration strategies to conserve the biodiversity of alpine lake riparian ecosystems. This research not only sheds light on the resilience and adaptability of ecosystems in the Qinghai-Tibetan Plateau but also offers valuable lessons for the conservation of similar habitats worldwide. Our findings underscore the need for tailored restoration strategies to conserve the biodiversity of alpine lake riparian ecosystems. This research not only sheds light on the resilience and adaptability of ecosystems in the Qinghai-Tibetan Plateau but also offers valuable lessons for the conservation of similar habitats worldwide.

The influence of grazing intensity on soil organic carbon storage in grassland of China: A meta-analysis.

Grazing can potentially affect grassland soil carbon storage through selective feeding, trampling and fecal excretion of livestock. The numerous case studies and a few meta-analyses have focused on grazing-induced changes in soil organic carbon (SOC) storage, but the effects of grazing on SOC in major grassland types of China are not clear. In this study, we performed a comprehensive meta-analysis to identify the impact of grazing on soil carbon in China. We found that the key factors affecting the SOC content of grazing grasslands is grazing intensity. Heavy grazing (HG) significantly decreased the SOC content by 7.5 % in major grassland types of China (95 % confidence interval (CI), -11.43 % to -3.57 %, P < 0.001). The SOC content in temperate desert steppes (7.22 %), temperate meadow-steppes (10.89 %) under heavy grazing (HG) showed significantly (P < 0.05) decreased. HG resulted in significant (P < 0.01) decreases in SOC content (6.91 %) of Kastanoze. Our study highlighted that formulating rational grazing strategies according to grassland and soil types was the key to increasing SOC storage and sequestration under climate change and increased human pressure.

Clinical and Radiological Outcomes After Combined ACL and MPFL Reconstruction Versus Isolated ACL Reconstruction for ACL Injury With Patellar Instability.

BACKGROUND: An anterior cruciate ligament (ACL) injury accompanied by patellar instability (PI) is a topic that has gained orthopaedic surgeons' attention recently. Untreated PI is reportedly associated with worse clinical outcomes after isolated ACL reconstruction (ACLR) in patients after an ACL injury with PI. Nevertheless, the appropriate surgical approach and its long-term therapeutic effects in these patients remain unclear. PURPOSE: (1) To compare the clinical and radiological outcomes between isolated ACLR (iACLR) and combined ACLR and medial patellofemoral ligament reconstruction (cAMR) in patients after an ACL injury with PI and (2) to explore the correlations between these 2 procedures and clinical and radiological outcomes. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 106 patients diagnosed with an ACL injury accompanied by PI between January 2016 and April 2021 were analyzed in this study. There were 34 patients excluded because of missing postoperative radiological data. Among the remaining 72 patients, 34 patients underwent iACLR, while 38 patients underwent cAMR. Demographic characteristics, intraoperative findings, and patient-reported outcomes (Lysholm score, subjective International Knee Documentation Committee score, and Tegner activity score) were prospectively collected. Patellar alignment parameters and worsening patellofemoral osteoarthritis (PFOA) features (evaluated with the modified Whole-Organ Magnetic Resonance Imaging Score) were analyzed longitudinally on magnetic resonance imaging. The Kujala score was used to evaluate the functional recovery of the patellofemoral joint, and redislocations of the patella were prospectively recorded. Finally, multivariate logistic regression analysis was used to explore the correlations between these 2 procedures and clinical (not achieving the minimal detectable change [MDC] for the Lysholm score) and radiological (worsening PFOA features) outcomes. RESULTS: The mean follow-up duration was 28.9 ± 6.2 and 27.1 ± 6.8 months for the iACLR and cAMR groups, respectively (P = .231). Significantly higher Lysholm scores (88.3 ± 9.9 vs 82.1 ± 11.1, respectively; P = .016) and subjective International Knee Documentation Committee scores (83.6 ± 11.9 vs 78.3 ± 10.2, respectively; P = .046) were detected in the cAMR group compared with the iACLR group postoperatively. The rates of return to preinjury sports were 20.6% and 44.7% in the iACLR and cAMR groups, respectively (difference, 24.1% [95% CI, 3.3%-45.0%]; P = .030). Moreover, the rates of worsening PFOA features were 44.1% and 18.4% in the iACLR and cAMR groups, respectively (difference, 25.7% [95% CI, 4.9%-46.4%]; P = .018). In addition, significantly higher Kujala scores (87.9 ± 11.3 vs 80.1 ± 12.0, respectively; P = .006), lower redislocation rates (0.0% vs 11.8%, respectively; difference, 11.8% [95% CI, 0.9%-22.6%]; P = .045), and significantly better patellar alignment were detected in the cAMR group compared with the iACLR group postoperatively. Furthermore, multivariate logistic regression analysis determined that iACLR and partial lateral meniscectomy were significantly correlated with not achieving the MDC for the Lysholm score and worsening PFOA features in our study population. CONCLUSION: In patients after an ACL injury with PI, cAMR yielded better clinical and radiological outcomes compared with iACLR, with better patellar stability and a lower proportion of worsening PFOA features. Furthermore, not achieving the MDC for the Lysholm score and worsening PFOA features were significantly correlated with iACLR and partial lateral meniscectomy. Our study suggests that cAMR may be a more appropriate procedure for patients after an ACL injury with PI, which warrants further high-level clinical evidence.

Impact of anthropogenic emission control in reducing future PM2.5 concentrations and the related oxidative potential across different regions of China.

Affected by both future anthropogenic emissions and climate change, future prediction of PM2.5 and its Oxidative Potential (OP) distribution is a significant challenge, especially in developing countries like China. To overcome this challenge, we estimated historical and future PM2.5 concentrations and associated OP using the Danish Eulerian Hemispheric Model (DEHM) system with meteorological input from WRF weather forecast model. Considering different future socio-economic pathways and emission scenario assumptions, we quantified how the contribution from various anthropogenic emission sectors will change under these scenarios. Results show that compared to the CESM_SSP2-4.5_CLE scenario (based on moderate radiative forcing and Current Legislation Emission), the CESM_SSP1-2.6_MFR scenario (based on sustainability development and Maximum Feasible Reductions) is projected to yield greater environmental and health benefits in the future. Under the CESM_SSP1-2.6_MFR scenario, annual average PM2.5 concentrations (OP) are expected to decrease to 30 (0.8 nmolmin-1m-3) in almost all regions by 2030, which will be 65 % (67 %) lower than that in 2010. From a long-term perspective, it is anticipated that OP in the Fen-Wei Plain region will experience the maximum reduction (82.6 %) from 2010 to 2049. Largely benefiting from the effective control of PM2.5 in the region, it has decreased by 82.1 %. Crucially, once emission reduction measures reach a certain level (in 2040), further reductions become less significant. This study also emphasized the significant role of secondary aerosol formation and biomass-burning sources in influencing OP during both historical and future periods. In different scenarios, the reduction range of OP from 2010 to 2049 is estimated to be between 71 % and 85 % by controlling precursor emissions involved in secondary aerosol formation and emissions from biomass burning. Results indicate that strengthening the control of anthropogenic emissions in various regions are key to achieving air quality targets and safeguarding human health in the future.

Investigating the cumulative lag effects of environmental exposure under urban differences on COVID-19.

Although all walks of life are paying less attention to COVID-19, the spread of COVID-19 has never stopped. As an infectious disease, its transmission speed is closely related to the atmosphere environment, particularly the temperature (T) and PM2.5 concentrations. However, How T and PM2.5 concentrations are related to the spread of SARS-CoV-2 and how much their cumulative lag effect differ across cities is unclear. To identify the characteristics of cumulative lag effects of environmental exposure under city differences, this study used a generalized additive model to investigate the associations between T/PM2.5 concentrations and the daily number of new confirmed COVID-19 cases (NNCC) during the outbreak period in the second half of 2021 in Shaoxing, Shijiazhuang, and Dalian. The results showed that except for PM2.5 concentrations in Shaoxing, the NNCC in the three cities generally increased with the unit increase of T and PM2.5 concentrations. In addition, the cumulative lag effects of T/PM2.5 concentrations on NNCC in the three cities reached a peak at lag 26/25, lag 10/26, and lag 18/13 days, respectively, indicating that the response of NNCC to T and PM2.5 concentrations varies among different regions. Therefore, combining local meteorological and air quality conditions to adopt responsive measures is an important way to prevent and control the spread of SARS-CoV-2.

Temporal and spatial variations and the relationships of land use pattern and ecosystem services in Qinghai-Tibet Plateau, China.

The Qinghai-Tibet Plateau is the key and largest ecological hotspot globally with enormous multiple ecosystem services. The vast and unique alpine ecosystems in this area have been subjected to the increased human disturbances, such as intensified land use. To explore the magnitude, spatiotemporal pattern and transformation process of land use in the Qinghai-Tibet Plateau and their impacts on the major ecosystem services during 1980-2020, we used the Integrated Valuation of Ecosystem Services and Trade-offs model to simulate the spatiotemporal variations of three types of ecosystem services, including habitat quality, carbon storage, and water yield. We analyzed the impacts of land use change on ecosystem services. The findings revealed that land use pattern remained generally stable from 1980 to 2020, with alpine grassland and desert as the dominant land use types. Habitat quality had generally enhanced, while carbon storage and water yield increased firstly and then declined. The magnitudes of three services gradually increased from the northwest to the southeast, corresponding to the spatial transformation pattern from desert via grassland to forest. The correlation between land use intensity and ecosystem services showed significant spatial heterogeneity, particulaly in counties greatly affected by land use intensity which concentrated predominantly in the mid-west, southern, and mid-east regions of the Qinghai-Tibet Plateau. The results have certain guiding significance for formulating land use policy and regulating land use pattern of alpine ecosystems in the Qinghai-Tibet Plateau.

Potential short-term effects of earthquake on the plant-soil interface in alpine grassland of the Qinghai-Tibetan Plateau.

Earthquakes are environmental disturbances affecting ecosystem functioning, health, and biodiversity, but their potential impacts on plant-soil interface are still poorly understood. In this study, grassland habitats in areas near and away from the seismo-fault in Madou, a region typical of alpine conditions on the Qinghai-Tibetan Plateau, were randomly selected. The impacts of earthquake on soil properties and plant nutrient content in the short term were emphasized, and their potential relationships with community diversity and productivity were examined. According to the findings of the study, the Maduo earthquake led to a decrease in soil nutrient content in alpine grassland ecosystems, especially soil TC, TN, TP, TCa, AP, AK, NH4 +-N, and SOC, and inhibited the absorption of N, Ca, and Mg nutrients by plants. In addition, the diversity and productivity of communities were affected by both direct and indirect earthquake pathways. The negative impacts of seismic fracture on soil structure had the most significant direct impact on plant community diversity. Earthquakes also indirectly reduced community productivity by reducing the soil N content and inhibiting the absorption of plant nutrients. Our findings suggested that earthquakes could potentially decrease the stability of the alpine grassland ecosystem on the QTP by affecting nutrient availability at the plant-soil interface.

Object use in insects.

Insects are the most diverse group of organisms in the animal kingdom, and some species exhibit complex social behaviors. Although research on insect object use is still in its early stages, insects have already been shown to display rich object-use behaviors. This review focuses on patterns and behavioral flexibility in insect object-use behavior, and the role of cultural evolution in the development of object-use behaviors. Object use in insects is not widespread but has been documented in a diverse set of taxa. Some insects can use objects flexibly and display various object-use patterns. Like mammals and birds, insects use objects in diverse activities, including foraging, predator defense, courtship, and play. Intelligence, pre-existing manipulative behaviors, and anatomical structure affect innovations in object use. In addition, learning and imitation are the main mechanisms underlying the spread of object-use behaviors within populations. Given that insects are one of the major animal groups engaging in object use, studies of insect object use could provide general insights into object use in the animal kingdom.

Effect of Anterior Acromial Coverage on Functional and Radiological Outcomes After Arthroscopic Repair of Anteroposterior Massive Rotator Cuff Tears.

BACKGROUND: Rotator cuff tear size, fatty infiltration, and scapular morphology are correlated with tendon healing and functional outcomes after arthroscopic repair; however, the association between anteroposterior acromial coverage and the clinical outcomes of anteroposterior massive rotator cuff tears (AP-MRCTs; involving all 3 tendons) remains unclear. PURPOSE: To identify the association between AP acromial coverage and functional and radiological outcomes after arthroscopic repair of AP-MRCTs. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 98 patients who underwent arthroscopic repair of AP-MRCTs between January 2015 and December 2020 were included in the study and classified according to whether anterior acromial coverage (AAC) was anterior (46 patients; positive AAC group) or posterior (52 patients; negative AAC group) to the scapular line on true lateral shoulder radiographs. Demographic characteristics, surgical details, and functional outcomes were prospectively collected. Acromial morphological features, global tear extension (GTE), the global fatty infiltration index (GFII), tendon integrity after repair, proximal humeral migration, and glenohumeral abduction were measured and calculated on radiographs or magnetic resonance imaging scans preoperatively and at 2 years postoperatively. Multivariate logistic regression was performed to identify the independent risk factors of a rotator cuff retear. RESULTS: The positive AAC group showed larger AAC, posterior acromial tilt, and anterior acromial slope as well as smaller posterior acromial coverage compared with the negative AAC group. Postoperatively, the American Shoulder and Elbow Surgeons score (82.5 ± 8.3 vs 77.2 ± 11.5, respectively; P = .013), active abduction (157.8°± 27.1° vs 142.7°± 39.6°, respectively; P = .048), and glenohumeral abduction (45.6°± 10.4° vs 39.7°± 14.9°, respectively; P = .041) in the positive AAC group were significantly higher than those in the negative AAC group, while the retear rate (23.9% vs 44.2%, respectively; P = .035) and proximal humeral migration (1.7 ± 1.0 vs 2.3 ± 1.2 mm, respectively; P = .006) were significantly lower in the positive AAC group than in the negative AAC group. Smaller AAC (odds ratio [OR], 0.93 [95% CI, 0.87-1.00]; P = .040), larger GTE (OR, 1.03 [95% CI, 1.01-1.06]; P = .017), and a higher GFII (OR, 3.49 [95% CI, 1.09-11.19]; P = .036) were associated with an increased risk of a rotator cuff retear. CONCLUSION: Increased AAC was associated with a lower retear rate and better functional outcomes after arthroscopic repair of AP-MRCTs. A preliminary risk evaluation integrating GTE, the GFII, and AAC is recommended to consider the necessity of additional procedures for patients in need of arthroscopic rotator cuff repair.

Vegetation structural shift tells environmental changes on the Tibetan Plateau over 40 years.

Structural information of grassland changes on the Tibetan Plateau is essential for understanding alterations in critical ecosystem functioning and their underlying drivers that may reflect environmental changes. However, such information at the regional scale is still lacking due to methodological limitations. Beyond remote sensing indicators only recognizing vegetation productivity, we utilized multivariate data fusion and deep learning to characterize formation-based plant community structure in alpine grasslands at the regional scale of the Tibetan Plateau for the first time and compared it with the earlier version of Vegetation Map of China for historical changes. Over the past 40 years, we revealed that (1) the proportion of alpine meadows in alpine grasslands increased from 50% to 69%, well-reflecting the warming and wetting trend; (2) dominances of Kobresia pygmaea and Stipa purpurea formations in alpine meadows and steppes were strengthened to 76% and 92%, respectively; (3) the climate factor mainly drove the distribution of Stipa purpurea formation, but not the recent distribution of Kobresia pygmaea formation that was likely shaped by human activities. Therefore, the underlying mechanisms of grassland changes over the past 40 years were considered to be formation dependent. Overall, the first exploration for structural information of plant community changes in this study not only provides a new perspective to understand drivers of grassland changes and their spatial heterogeneity at the regional scale of the Tibetan Plateau, but also innovates large-scale vegetation study paradigm.

Different responses of alpine plants to natural climate change reduced coexistence through phenological niche overlap.

Plant phenology is the bridge between climate change and ecosystem functions. Time coordination of interspecific and intraspecific phenology changes overlap or separate can be regarded as an important characteristic of species coexistence. To confirm the hypothesis that plant phenological niche promotes species coexistence, three key alpine plants, Kobresia humilis (sedge), Stipa purpurea (grass), and Astragalus laxmannii (forb) were investigated in this study in the Qinghai-Tibet Plateau. Phenological niches represented as the duration of green up-flowering, flowering-fruiting, and fruiting-withering by 2-day intervals for phenological dynamics of three key alpine plants from 1997 to 2016. We found the role of precipitation on regulating the phenological niches of alpine plants was highlighted in the context of climate warming. The response of the intraspecific phenological niche of the three species to temperature and precipitation is different, and the phenological niche of Kobresia humilis and Stipa purpurea was separate, especially in the green up-flowering. But the overlapping degree of interspecific phenological niche of the three species has continued to increase in the past 20 years, reducing possibility of species coexistence. Our findings have profound implications for understanding the adaptation strategies of key alpine plants to climate change in the dimension of phenological niche.

Anchoring grassland sustainability with a nature-based small burrowing mammal control strategy.

Over the last 40 years, a burrowing mammal eradication policy has been prevalent on the Qinghai-Tibetan Plateau (QTP). This policy is based on similar burrowing mammal eradication programs in other areas and is justified on the assumptions that burrowing mammals compete with livestock for forage and contribute to grassland degradation. However, there is no clear theoretical or experimental evidence supporting these assumptions. This paper synthesizes the ecological functioning of small burrowing mammals in natural grasslands and discusses the irrationality and consequences of burrowing mammal eradication for sustainable livestock grazing and grassland degradation. Past burrowing mammal eradication efforts have failed because increased food availability for the remaining rodents and reduced predator populations led to rapid population rebounds. Herbivores differ in diet, and there is clear evidence that burrowing mammals, especially plateau zokors Myospalax baileyi, have a different diet than livestock. In QTP meadows, burrowing mammal eradication induces a shift towards plant communities with fewer species preferred by livestock and more species preferred by burrowing mammals. Thus, eradicating burrowing mammals has the opposite effect, a reduction in livestock preferred vegetation. We suggest that the policy of poisoning burrowing mammals needs to be reconsidered and revoked as soon as possible. We argue that incorporating density-dependent factors such as predation and food availability are essential for maintaining a low burrowing mammal density. For degraded grasslands, we suggest that the optimal sustainable approach is to decrease the intensity of livestock grazing. Lower grazing induces changes in vegetation structure and plant species composition that increases predation on burrowing mammals and decreases the abundance of plants preferred by burrowing mammals. Such a nature-based grassland management system maintains the density of burrowing mammals at a low stable density while minimizing human management and interventions.