Climate warming and atmospheric nitrogen(N)deposition have profound influences on the terrestrial biosphere.However,how these two global change drivers affect phytoplankton which are important primary producers in wet...Climate warming and atmospheric nitrogen(N)deposition have profound influences on the terrestrial biosphere.However,how these two global change drivers affect phytoplankton which are important primary producers in wetlands with large carbon stocks and complex hydrological fluctuations remain largely unclear.As part of a two-year field experiment in a freshwater wetland,this study was conducted to investigate the effects of nighttime warming and N addition on phytoplankton biomass in the North China Plain.The results showed that neither nighttime warming nor N addition influenced the Shannon-Wiener index of phytoplankton community.Nighttime warming did not change phytoplankton biomass,likely due to the different warming impacts on dominant phyla and in different seasons.Decreased phytoplankton biomass in spring because of the increased water pH and submerged plant coverage was compensated by the enhanced biomass in autumn due to the reduced dissolved oxygen and submerged plant coverage,leading to the neutral change of phytoplankton biomass under warming.Nitrogen addition elevated phytoplankton biomass by 11.6%,which could be attributed to the enhanced nutrient availability and reduced submerged plant coverage.Positive relationships of methane(CH4)emission rates at the water-air interface with phytoplankton biomass indicated the potentially crucial role of phytoplankton in mediating wetland CH4 cycling through photosynthesis-driven metabolisms.The findings suggested the seasonal variation of phytoplankton and their potential responses to nighttime warming and N deposition,which may provide a more accurate basis for assessing the global change-carbon feedback in wetland ecosystems.展开更多
水生植被和藻类作为湖泊生态系统的主要初级生产者,对湖泊生态系统具有重要作用。在气候变化和人类活动的双重作用下,湖泊富营养化加剧,水生植被退化,藻类水华频发。开展湖泊水生植被群落和藻类水华的长期观测可为湖泊生态系统水生植被...水生植被和藻类作为湖泊生态系统的主要初级生产者,对湖泊生态系统具有重要作用。在气候变化和人类活动的双重作用下,湖泊富营养化加剧,水生植被退化,藻类水华频发。开展湖泊水生植被群落和藻类水华的长期观测可为湖泊生态系统水生植被修复和藻类水华管控提供决策依据。本研究以太湖流域浅水湖泊长荡湖为研究区,基于1985-2021年的Landsat 5和8卫星数据,利用VBI(vegetation and bloom indices)草藻分类算法,开展了浮叶/挺水植被、沉水植被和藻类水华长时序时空演变分析。结果表明:36年来,长荡湖水生植被(包括浮叶/挺水植被和沉水植被)都呈现显著下降趋势,其中沉水植被下降趋势尤为明显,沉水植被从湖中心向岸边逐步退化,其覆盖度从1985年的75%下降至2021年的不足21%;自2011年起,长荡湖水生植被优势生活型从沉水植被转变为浮叶/挺水植被;2010年首次监测到水华发生,2020年和2021年连续两年均监测到湖中心有大面积水华。基于湖泊围网面积和气象数据分析发现,围网拆除是水生植被退化和优势生活型转变的主要因素。展开更多
基金supported by the Science and Technology Project of Hebei Education Department(No.QN2023028)the Natural Science Foundation of Hebei Province(No.C2022201042)+1 种基金the High-level Talent Research Funding Project of Hebei University(Nos.521000981405 and 521000981186)the Collaborative Innovation Center for Baiyangdian Basin Ecological Protection and Beijing-Tianjin-Hebei Sustainable Development.
文摘Climate warming and atmospheric nitrogen(N)deposition have profound influences on the terrestrial biosphere.However,how these two global change drivers affect phytoplankton which are important primary producers in wetlands with large carbon stocks and complex hydrological fluctuations remain largely unclear.As part of a two-year field experiment in a freshwater wetland,this study was conducted to investigate the effects of nighttime warming and N addition on phytoplankton biomass in the North China Plain.The results showed that neither nighttime warming nor N addition influenced the Shannon-Wiener index of phytoplankton community.Nighttime warming did not change phytoplankton biomass,likely due to the different warming impacts on dominant phyla and in different seasons.Decreased phytoplankton biomass in spring because of the increased water pH and submerged plant coverage was compensated by the enhanced biomass in autumn due to the reduced dissolved oxygen and submerged plant coverage,leading to the neutral change of phytoplankton biomass under warming.Nitrogen addition elevated phytoplankton biomass by 11.6%,which could be attributed to the enhanced nutrient availability and reduced submerged plant coverage.Positive relationships of methane(CH4)emission rates at the water-air interface with phytoplankton biomass indicated the potentially crucial role of phytoplankton in mediating wetland CH4 cycling through photosynthesis-driven metabolisms.The findings suggested the seasonal variation of phytoplankton and their potential responses to nighttime warming and N deposition,which may provide a more accurate basis for assessing the global change-carbon feedback in wetland ecosystems.
文摘水生植被和藻类作为湖泊生态系统的主要初级生产者,对湖泊生态系统具有重要作用。在气候变化和人类活动的双重作用下,湖泊富营养化加剧,水生植被退化,藻类水华频发。开展湖泊水生植被群落和藻类水华的长期观测可为湖泊生态系统水生植被修复和藻类水华管控提供决策依据。本研究以太湖流域浅水湖泊长荡湖为研究区,基于1985-2021年的Landsat 5和8卫星数据,利用VBI(vegetation and bloom indices)草藻分类算法,开展了浮叶/挺水植被、沉水植被和藻类水华长时序时空演变分析。结果表明:36年来,长荡湖水生植被(包括浮叶/挺水植被和沉水植被)都呈现显著下降趋势,其中沉水植被下降趋势尤为明显,沉水植被从湖中心向岸边逐步退化,其覆盖度从1985年的75%下降至2021年的不足21%;自2011年起,长荡湖水生植被优势生活型从沉水植被转变为浮叶/挺水植被;2010年首次监测到水华发生,2020年和2021年连续两年均监测到湖中心有大面积水华。基于湖泊围网面积和气象数据分析发现,围网拆除是水生植被退化和优势生活型转变的主要因素。
