香格里拉灌木、草本植物区系与垂直分布格局

草地作为全球生态系统功能服务最重要的组成部分，是农林牧业发展的基础，探究灌木、草本植物区系与地理分布特征对于揭示区域物种多样性和生物保护策略具有十分重要的意义。本研究通过野外样地调查和历史记录数据库，采用吴征镒植物区系分区方法，对香格里拉灌木和草本植物多样性、区系特点与垂直分布格局进行系统分析。结果表明：1)该区灌木、草本植物物种丰富，共有121科619属2 442种，其中草本植物占优，有94科514属2 048种。2)在科、属构成中，优势科属明显，单种科、寡种属比例高，占比分别为32.23%和51.05%，中国特有属极其丰富，共有28种。3)区系成分多样，含有13个科地理成分及15个属地理分布类型，科的区系分布类型以世界分布、泛热带分布和北温带分布为主，热带性与温带性分布的比值为1.29，热带分布型稍占优势；属的区系分布类型以北温带分布、东亚分布、泛热带分布为主，且热带性与温带性分布的比值为0.39，温带分布型占据主导地位。4)在垂直分布上，随着海拔的升高，热带区系成分占比逐渐降低、温带区系成分逐渐上升，物种丰富度呈先升后降的单峰分布格局，灌木、草本植物物种丰富度峰值位于2 600～2 900 m和3 200～3 500 m处，各海拔段草本物种数量均极显著高于灌木(P < 0.01)。本研究旨在展现“三江并流”世界自然遗产中心地带的植物多样性和同纬度地区植物分区特点，对当地灌木和草本植被生态修复物种选择和合理利用具有重要参考价值。     

Total bilirubin is an independent predictor of death in dogs with degenerative valvular disease and dilated cardiomyopathy

IntroductionThere is little published regarding the association between canine cardiovascular disease and the hepatic system. The objective of the study was to evaluate the relationship between hepatic parameters, survival, and disease stages of dogs with either dilated cardiomyopathy (DCM) or degenerative valvular disease (DVD).Animals, materials, and methodsRetrospective study analyzing hepatic parameters in dogs with DVD or DCM in American College of Veterinary Internal Medicine stage B or C and healthy control dogs. Associations between liver parameters, type and stage of disease, and survival were investigated.ResultsNinety-nine dogs were included in the study: 61 DVD, 22 DCM, and 16 controls. Differences in liver parameter concentrations between DCM, DVD, and disease stages were found. Univariate analysis identified alanine aminotransferase (P < 0.001), aspartate aminotransferase (P = 0.02), and total bilirubin (P = 0.005) as predictors of mortality. In the multivariate analysis, total bilirubin remained an independent predictor of mortality.ConclusionsThe observed differences between DCM, DVD, and disease stages are likely consistent with disease-specific hemodynamics and progression of disease. This and the role of total bilirubin as an independent predictor for mortality indicate that in dogs with DVD and DCM the cardiovascular–hepatic interaction might be of relevance for disease progression and outcome, as reported for humans with cardiac disease. Further studies into the role of hepatic function in canine cardiac disease are required.     

Augmenting freshwater availability in mountain headwater streams: Assessing the sustainability under baseline and future climate change scenarios

Mountain headwater streams are important freshwater sources, but they are mostly intermittent and highly susceptible to climate change. This paper examines the sustainability of augmented freshwater availability in mountain headwater streams for water supply under baseline and future climate change scenarios using an integrated modeling approach. The climate change data in the 2040s (2030–2059), under Representative Concentration Pathway 4.5 and 8.5 scenarios, were downscaled for the impact assessment. In the region, climate change raises the average precipitation by 5–7% and the temperature by 13–15% in the 2040s. SWAT–MODFLOW model, integrating Soil and Water Assessment Tool (SWAT2012) and finite-difference Modular Groundwater Flow (MODFLOW) models in a single package, was used to assess the water balance. Results show that extracting a minimum of 16.2 m³/day from the sand storage and 30 m³/day from the aquifer was possible without affecting the groundwater table and water yield. The average annual catchment recharge was 6% of the precipitation under the baseline simulation. Climate change is projected to reduce the average water yield and groundwater recharge by 26% and 19%, respectively. However, the water supply-demand is significantly small compared to the exploitable rate of water in the area. This study was based on limited data, and therefore the findings need to be interpreted with caution, though the model output was validated using satellite products. Construction of a series of sand dams is suggested to maximize the benefit under the potential climate change and water supply-demand increase.     

Can food security and low carbon be achieved simultaneously? —An empirical analysis of the mechanisms influencing the carbon footprint of potato and corn cultivation in irrigation areas

Irrigated agriculture has tripled since 1950, accounting for 20% of the global arable land and 40% of food production.  Irrigated agriculture increases food security yet has controversial implications for global climate change.  Most previous studies have calculated carbon emissions and their composition in irrigated areas using the engineering approach to life-cycle assessment.  By combining life cycle assessment (LCA)-based carbon emissions accounting with econometric models such as multiple linear regression and structural equation modeling (SEM), we conducted an interdisciplinary study to identify the influencing factors and internal mechanisms of the carbon footprint (CFP) of smallholder crop cultivation on irrigation reform pilot areas.  To this end, we investigated corn and potato production data in the 2019–2020 crop years for 852 plots of 345 rural households in six villages (two irrigation agriculture pilot villages and four surrounding villages as controls) in Southwest China.  The crop CFP in the irrigation agriculture pilot areas was significantly lower than in non-reform areas.  Irrigation reforms mainly impacted the crop CFP through four intermediary effects: the project (implementation of field irrigation channels), technology (improving adoption of new irrigation technologies), management (proper irrigation operation and maintenance), and yield effects.  All effects inhibited the CFP, except for the project effect that promotes carbon emissions.  Among them, yield increase has the greatest impact on reducing CFP, followed by management and technology effects.  Furthermore, planting practices, individual characteristics, and plot quality significantly impacted the crop CFP.  This study has policy implications for understanding the food security–climate nexus in the food production industry.