Drivers of biodiversity loss in freshwater environments: A bibliometric analysis of the recent literature

1. Species are disappearing at a rate comparable with previous mass extinctions. Freshwater environments are being particularly affected, with biodiversity losses occurring much faster in freshwater than in terrestrial or marine ecosystems.
2. This study assessed the research on drivers of biodiversity loss in freshwater environments as described in nearly 37,000 articles published in the last decade. Articles on biodiversity published between 2010 and 2019 were retrieved from the Web of Science to determine the number of articles that addressed a particular driver of biodiversity loss, by analysing the titles, abstracts, and keywords. The biodiversity and development status of a country was also investigated to see how it affects its scientific output (i.e. number of published articles).
3. Twenty per cent of the articles on biodiversity addressed freshwater biodiversity. Researchers devoted considerable effort to six drivers – climate change, water pollution, flow modification, expanding hydropower, species invasions, and habitat degradation – but practically ignored other threats, such as plastic and light pollution. It was also found that megadiverse countries, which for the most part were also developing countries, published substantially fewer articles than developed but less biodiverse countries.
4. We recommend a series of actions that could contribute to mitigate the biases found in this study.

     

Fishing down the deep

Global landings of demersal marine fishes are demonstrated to have shifted to deeper water species over the last 50 years. Our analysis suggests deep‐water fish stocks may be at serious risk of depletion, as their life histories render them highly vulnerable to overfishing with little resilience to over‐exploitation. Deep‐sea fisheries are exploiting the last refuges for commercial fish species and should not be seen as a replacement for declining resources in shallower waters. Instead, deep‐water habitats are new candidates for conservation.     

More than a ‘blip’: The changed character of South‐East Asia’s engagement with the global economy in the post‐1997 period

Abstract: Through reviewing South‐East Asia’s recent economic engagement with the global economy, this paper points to profound recent transformations in the scope and character of the region’s development. Foreign direct investment was the key driver of regional growth in the pre‐1997 period, yet currently, the region faces a more difficult and multifaceted economic arena from which to attract such funds. Foreign direct investment is more selective, both geographically and by sector, than was the case in that earlier period. This paper explains the confluence of economics, business practices and politics that are giving rise to these outcomes, and concludes from this that development trajectories in South‐East Asia will become more diverse between the countries of the region, with implications for how we understand regional economic performance.     

Seasonal Plant Water Relationships in Acacia berlandieri

In order to assess how plant water potential is related to soil water availability and evaporative demand, determinations of diurnal and seasonal plant water potentials between 23 April 1997, and 22 September 1998, were studied in Acacia berlandieri Benth., a native shrub of the northeastern region of Mexico. Average plant water potentials during the wettest period ranged from-0.37 MPa (predawn, PD) to -2.79 MPa (midday, MD )whereas, during the long, hot, and severe drought period PD and MD water potentials measurements diminished down to -5.9 and -6.8 MPa, respectively. Average diurnal depression of plant water potential (calculated as the difference between midday and predawn water potentials) during the wettest and driest season varied from -2.28 - 0.50 MPa to -0.86 - 0.46 MPa, respectively. An exponential function was found between PD water potential with average soil water content and vapor pressure deficit (VPD). Both variables supported about 85% and 66%, respectively, of the variability in PD water potential. PD water potential values were high and relatively constant above soil water content of 0.17 kg kg-¹; below this threshold value the PD water potential declined. Highest positive (r = 0.870) and negative (r = -0.706) correlation coefficients of PD water potential data were observed with soil moisture content at the 20-30cm soil layer and VPD, respectively. MD water potential, VPD, and air temperature explained about 83% of the variation in PD water potential. Soil water content at the 20-30cm soil layer, PD water potential, andrelative humidity described about 82% of the variation in MD water potential. It was concluded A. berlandieri can endure substantial drydown periods and its water relations are strongly associated with soil water content and atmospheric evaporative demand components.     

后金融危机时期中国农业科技发展若干问题的思考——高度重视原始创新，抢占农业科技前沿领域的制高点

2008年美国爆发金融危机后,欧债危机随后爆发,新兴经济体也受到严重冲击,世界经济增速放缓。历史经验表明,经济危机往往孕育着新的科技革命。在经济全球化的背景下,谁能在科技创新方面占据优势,谁就能够掌握发展的主动权,率先复苏并走向繁荣。而作为基础产业的农业和农业科技进步对中国经济发展具有举足轻重的作用。为此,应充分抓住金融危机给农业科技发展带来的机遇,高度重视科技原始创新能力的培养,要做到遵循农业科研规律,优化配置农业基础科技资源,强化农业基础研究和高新技术研究,提升农业核心技术研发水平,加快完善科学评价体系,超前部署一批前瞻性科技专项,增强科技战略储备能力,抢占以生物技术、信息技术、先进制造技术等为核心的农业科技前沿领域的制高点,以科技创新促进现代农业发展。     

连云港近岸海域表层沉积物中重金属的分布特征及潜在生态危害

采用变异系数、富集系数、潜在生态危害指数分析评价连云港近岸海域表层沉积物中的重金属的相关特性。结果表明:重金属的空间分布离散性及富集程度存在明显差异,重金属元素空间波动程度依次为Cu=Cd>Hg>Cr>As>Zn>Pb,富集程度依次为Zn>Cr>Cd>Cu>As>Pb>Hg;除Cd在5号站位处于中等污染水平外,其他各重金属的潜在生态危害处于轻微水平,潜在生态危害系数依次为Cd>Hg>As>Cu>Pb>Cr>Zn,港口区域重金属富集程度较重,潜在生态危害指数相对较高;有机碳和酸可挥发性硫化物影响到重金属的迁移与转化,进而影响其潜在生态危害程度及生物毒性。     

新乡市环宇大道工业区周边土壤重金属的污染特征和评价

通过实地采样及室内化学分析的方法,研究了新乡市环宇大道工业区周边土壤Pb、Cd、Ni、Zn、Cu和Cr 6种重金属污染特征和风险评价,并应用Tessier五步连续萃取的方法对土壤中超标的Cd,Ni和Zn进行形态分析。结果表明:(1)土壤中Pb、Cd、Ni、Zn、Cu和Cr的平均含量分别是63.08 mg kg-1、176.85 mg kg-1、307.2 mg kg-1、485.6 mg kg-1,38.7 mg kg-1和47.9 mg kg-1,Pb、Cu、Cr平均含量达标,Cd、Ni、Zn平均含量均超标,分别是国家土壤环境质量二级标准的176.85、5.12、1.62倍。(2)Ni和Zn主要以铁锰氧化物结合态和残渣态存在,Cd主要以铁锰氧化物结合态存在,其次为碳酸盐结合态,3种重金属的迁移能力依次为:Cd>Zn>Ni。(3)每种重金属都存在不同程度的潜在生态风险,Cd的潜在生态风险最大并构成了很强的危害。     

基于GeoEye-1高分遥感影像的冬小麦氮肥推荐应用

为给大区域范围的冬小麦氮素营养遥感诊断及其精准施肥决策提供参考,将GeoEye-1高分辨率遥感影像数据与氮肥优化算法(NFOA)相结合,开展了冬小麦氮肥推荐应用研究。首先,基于多年地面实测冬小麦冠层高光谱数据,利用光谱响应函数生成GeoEye-1卫星遥感模拟数据,计算得到归一化植被指数NDVI,并结合当季估产指数INSEY构建了冬小麦潜在产量预测模型;通过定义可表征小麦氮素丰缺的氮素响应指数RINDVI,结合潜在产量模型,计算得到氮素需求量;最后,利用GeoEye-1高分辨率遥感影像数据进行验证分析,将氮素推荐模型与高分辨率遥感数据相结合生成施肥推荐处方图,实现了冬小麦的氮素营养诊断及施肥推荐。结果表明,当季估产指数INSEY可很好地估算冬小麦的潜在产量(r2=0.606,RMSE=0.704t·hm-2),基于GeoEye-1高分遥感影像提取NDVI预测的潜在产量与实测产量显著相关(r2=0.722,RMSE=0.451t·hm-2)。氮素响应指数RINDVI与氮营养指数NNI的倒数也显著相关(r=0.915),可以用RINDVI来诊断冬小麦氮素的丰缺状态。以上结果说明,在没有地面实测小麦氮含量、生物量、地面光谱等数据的情况下,利用高分辨率遥感数据与气象数据构建模型可估算冬小麦的潜在产量,并能实现对冬小麦的氮营养诊断及生成推荐施肥处方。     

外围国家如何破除资本主义系统性危机的影响——基于萨米尔·阿明依附理论的分析

萨米尔·阿明的依附理论揭示了资本主义系统性危机的实质和危害，提出外围国家唯有与中心国家"脱钩"，才能摆脱资本主义体系并构建一个社会主义世界。中心国家的经济长期停滞，自我调适措施又引发新的矛盾，使当代资本主义日益走向内外交困的衰落境地。外围国家在经济、政治、文化、军事等方面遭受着中心国家侵略，深受资本主义系统性危机的影响，现代化建设十分困难。只有独立自主地走适合民族自身发展的道路，坚持对外开放，坚持合作共赢，主动防范外部风险，外围国家才能斩断与中心国家的被动依附关系，实现平等发展，破除资本主义系统性危机的影响。     

节水灌溉的迫切性及其评价指标与分析

 就全球面临水资源匮缺的严峻形势,分析中国水资源分布现状及目前水情危机的状况,呼吁节约用水、提倡节水灌溉。从节水灌溉定义的内涵出发,指出推广实施节水灌溉的迫切性并提出节水灌溉的评价指标,且对其进行科学分析。