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Urbanization reduces resource use efficiency of phytoplankton community by altering the environment and decreasing biodiversity

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Journal of Environmental Sciences 2022年第2期34卷 140-151页

作者： Yigang Yang Huihuang Chen Mamun Abdullah Al Jean Claude Ndayishimiye Jun R Yang alain isabwe Anqi Luo Jun Yang Aquatic EcoHealth Group Fujian Key Laboratory of Watershed EcologyKey Laboratory of Urban Environment and HealthInstitute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China Engineering Research Center of Ecology and Agricultural Use of Wetland(Ministry of Education) College of AgricultureYangtze UniversityJingzhou 434025China

Urbanization often exerts multiple effects on aquatic and terrestrial organisms,including changes in biodiversity,species composition and ecosystem ***,the impacts of urbanization on river phytoplankton in subtropical urbanizing watersheds remain largely ***,we explored the effects of urbanization on phytoplankton community structure(i.e.,biomass,community composition and diversity)and function(i.e.,resource use efficiency)in a subtropical river at watershed scale in southeast China over 6 years.A total of 318 phytoplankton species belonging into 120 genera and 7 phyla were identified from 108 *** biomass showed an increasing trend with increasing urbanization *** phytoplankton community shifted from Chlorophyta dominance in rural upstream waters to Bacillariophyta dominance in urbanized downstream ***,phytoplankton diversity and resource use efficiency(RUE=phytoplankton biomass/total phosphorus)were significantly decreased with increasing urbanization level from upstream to *** RUE exhibited a significant positive correlation with species richness,but a negative correlation with phytoplankton *** variation in environmental factors(turbidity,total nitrogen,NH_(4)^(+)-N,total phosphorus,PO_(4)^(3-)-P and percentage urbanized area)was significantly correlated with phytoplankton diversity and ***,our results revealed the influence of urbanization on phytoplankton community structure and ecosystem function was due to its altering the environmental ***,human-driven urbanization may play crucial roles in shaping the structure and function of phytoplankton communities in subtropical rivers,and the mechanism of this process can provide important information for freshwater sustainable uses,watershed management and conservation.

关键词： Plankton Community functioning Subtropical river Urbanization gradient Land use Watershed ecology

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大坝建设对九龙江流量和沉积物输运的影响评估

大坝建设对九龙江流量和沉积物输运的影响评估

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作者： alain isabwe 厦门大学

学位级别：硕士

由于全球气候变化和不断增加的人类活动已经影响到全球河流,最近人们对有关河流入海泥沙和水流量的问题越来越关注。反过来,通过河流的输送,海洋生态系统变的越来越脆弱。从这个角度来看,本研究以沿海河流—九龙江为研究区域为例,评估... 详细信息

由于全球气候变化和不断增加的人类活动已经影响到全球河流,最近人们对有关河流入海泥沙和水流量的问题越来越关注。反过来,通过河流的输送,海洋生态系统变的越来越脆弱。从这个角度来看,本研究以沿海河流—九龙江为研究区域为例,评估在河道上筑坝对水流量和泥沙量变化所带来的影响。利用建坝前后长期对水流量和悬浮沉积物的监测数据,结合6个月(从2013年11月至2014年4月)在九龙江代表站位——西陂库区,野外采样获取的短期悬浮沉积物的数据,应用简单线性回归可以发现二者的长期变化趋势。根据本研究的估计,从建坝前到建坝后,水流量减少了7.9%,泥沙量增加了24%。相比于建坝前水流量和泥沙量的平均值分别是83.9×108m3/a和6.42105Kg/a,建坝后二者平均值的分别是83.7×108m3/a和8.02×105Kg/a。相比于建坝后,建坝前的干季(比如十月份到第二年的四月份)数据显示有较高的泥沙量和较低的水流量。库区的悬浮沉积物的量随着水深的增加和坝前距离的减小而增加。水流量和泥沙量的长期变化趋势也可能部分受到其他因素的影响,比如九龙江流域的人口数量增加、水土保育措施的失败、农业用地、土壤类型、森林覆盖率的改变等。这些变化导致了各种各样的后果,比如水质的变化、营养盐浓度的增加、水体分层、入海泥沙量的变化、微量金属的分布以及潜在的富营养化,在本研究看来,导致这些后果的部分原因可归因于水流量和泥沙量的变化。我们可以针对河流提出适当的管理建议,类似的研究应该推广到底沙。对于九龙江综合一体的流域管理,我们应扩展由建坝引起的环保流的研究评估。

关键词：水流量泥沙量水坝九龙江

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Inter-Annual Vegetation Changes in Response to Climate Variability in Rwanda

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Journal of Environmental Protection 2017年第4期8卷 464-481页

作者： Felix Ndayisaba Hao Guo alain isabwe Anming Bao Lamek Nahayo Garee Khan Alphonse Kayiranga Fidele Karamage Enan Nyesheja Muhire State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi China University of Chinese Academy of Sciences Beijing China Aquatic EcoHealth Group Key Laboratory of Urban Environment and Health Institute of Urban Environment Chinese Academy of Sciences Xiamen China University of Lay Adventists of Kigali (UNILAK) Kigali Rwanda

Comprehensive studies on how vegetative ecosystems respond to fluctuations in precipitation and temperature patterns are of great necessity for environmental risk assessment and land-use evaluations. The present study examined the annual trends in vegetation greenness in Rwanda from 2000-2015 and assessed the relationship between these dynamics and climate factors by means of MODIS NDVI, air temperature, SOI and precipitation datasets. Mann Kendal trend test has been utilized to determine the direction and the rates of changes, while Spearman’s rank correlation method has been used to determine the levels of associability between NDVI changes and climatic variables. The results indicate that approximately 11.9% of the country’s vegetation has significantly improved (р < 0.05) from slight to significant improvement while 10.4% of the vegetative cover degraded from slight to severe degradation and an estimated 77.6% of the country’s vegetation cover has remained relatively stable. Much of improvement has been detected in the lowlands of eastern province whereas much of degradation has been highlighted in the western highlands of the Congo Nile ridge and Kigali city. There was a weak correlation between NDVI anomalies and SOI anomalies (rs = 0.36) while near surface air temperature was moderately correlated (rs = 0.47) with changes in Mean NDVI. Precipitation was more significantly associated (r = 0.84) with changes in vegetation health in low plains of Eastern Province (Nyagatare District in particular) than in the high altitude regions of the Congo Nile ridge. A strong positive correlation with precipitation was found in rain fed croplands;mosaic vegetation;mosaic forest or shrubland, herbaceous vegetation/grass-land savannah and sparse vegetation. Identification of degradation hotspots could significantly help the government and local authorities galvanize efforts and foster results driven policies of environmental protection and regeneration countrywide.

关键词： MODIS NDVI Mann Kendall Test Vegetation Health Rwanda Climate

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