摘要：
The impact of global warming on plant abundance has been widely discussed, but it remains unclear how warming affects plant physiological traits, and how these traits contribute to the abundance of aquatic plants. We explored the adjustments in physiological traits of two common aquatic plant species (Potamogeton crispus L. and Elodea canadensis Michx.) and their links to plant abundance in three temperature treatments by determining twelve physiological traits and plant abundance over an 11-month period in outdoor mesocosms. This mesocosms facility has been running uninteruptedly for 16years, rendering the plants a unique opportunity to adapt to the warming differences. We found that 1) warming reduced the starch storage in winter for P. crispus and in summer for E. canadensis while increased the nitrogenous substances (e.g., TN, FAA, and proline) in winter for P. crispus. 2) For E. canadensis, TC, starch, SC, and sucrose contents were higher in summer than in winter regardless of warming, while TC, SC, and sucrose contents were lower in summer for P. crispus. 3) Warming decreased the association strength between physiological traits and plant abundance for P. crispus but enhanced it for E. canadensis. 4) E. canadensis showed increased interaction strength among physiological traits under warming, indicating increased metabolic exertion in the response to warming, which contributed to the reduction in abundance. Trait interaction strength of P. crispus was reduced under warming, but with less impact on plant abundance compared with E. canadensis. Our study emphasizes that warming alters the network of plant physiological traits and their contribution to abundance and that different strengths of susceptibility to warming of the various plant species may alter the composition of plant communities in freshwater ecosystems.
作者机构：
[Yili Ge; Zheng Dong; Yu Liao; Yaoqi Chen; Aiping Wu; Youzhi Li; Huanyao Liu; Guixiang Yuan; Hui Fu] Ecology Department, College of Environments & Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Hunan Agricultural University, Changsha 410128, PR China;Institute of Mountain Resources, Guizhou Academy of Science, Guiyang 550001, PR China;[Jianming Deng] Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China;Department of Ecoscience and Centre for Water Technology (WATEC), Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark;Sino-Danish Centre for Education and Research (SDC), University of Chinese Academy of Sciences, Beijing, China
通讯机构：
[Jianming Deng] T;[Hui Fu] E;Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China<&wdkj&>Ecology Department, College of Environments & Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Hunan Agricultural University, Changsha 410128, PR China
摘要：
Phytoplankton communities are crucial components of aquatic ecosystems, and since they are highly interactive, they always form complex networks. Yet, our understanding of how interactive phytoplankton networks vary through time under changing environmental conditions is limited. Using a 29-year (339 months) long-term dataset on Lake Taihu, China, we constructed a temporal network comprising monthly sub-networks using "extended Local Similarity Analysis" and assessed how eutrophication, climate change, and restoration efforts influenced the temporal dynamics of network complexity and stability. The network architecture of phytoplankton showed strong dynamic changes with varying environments. Our results revealed cascading effects of eutrophication and climate change on phytoplankton network stability via changes in network complexity. The network stability of phytoplankton increased with average degree, modularity, and nestedness and decreased with connectance. Eutrophication (increasing nitrogen) stabilized the phytoplankton network, mainly by increasing its average degree, while climate change, i.e., warming and decreasing wind speed enhanced its stability by increasing the cohesion of phytoplankton communities directly and by decreasing the connectance of network indirectly. A remarkable shift and a major decrease in the temporal dynamics of phytoplankton network complexity (average degree, nestedness) and stability (robustness, persistence) were detected after 2007 when numerous eutrophication mitigation efforts (not all successful) were implemented, leading to simplified phytoplankton networks and reduced stability. Our findings provide new insights into the organization of phytoplankton networks under eutrophication (or re-oligotrophication) and climate change in subtropical shallow lakes.
通讯机构：
[Hong-Yuan Zeng; Ai-Ping Wu] A;Authors to whom correspondence should be addressed.<&wdkj&>Hunan Institute of Microbiology, Changsha 410009, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>Ecology Department, College of Resources and Environment, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Hunan Agricultural University, Changsha 410128, China
摘要：
Water level rise is considered an environmental filter for the growth and reproduction of aquatic plants in lakes. Some emergent macrophytes can form floating mats, enabling them to escape from the negative effects of deep water. However, an understanding of which species can be uprooted and form floating mats easily and what factors affect these tendencies remains greatly elusive. We conducted an experiment to determine whether the monodominance of Zizania latifolia in the emergent vegetation community in Lake Erhai was related to its floating mat formation ability and to try to find the reasons for its floating mat formation ability during the continuous increase in water level over the past few decades. Our results showed that both the frequency and biomass proportion of Z. latifolia were greater among the plants on the floating mats. Furthermore, Z. latifolia was more likely to be uprooted than the other three previously dominant emergent species due to its smaller angle between the plant and the horizontal plane, rather than the root:shoot or volume:mass ratios. The dominance of Z. latifolia in the emergent community in Lake Erhai is due to its easier ability to become uprooted, allowing it to outperform other emergent species and become the single dominant emergent species under the environmental filter of deep water. The ability to uproot and form floating mats may be a competitive survival strategy for emergent species under the conditions of continuous significant water level rise.
关键词：
aquatic plant;eutrophication;plant traitnetwork;littoral zone
摘要：
Our study elucidates how eutrophicationpromotes aquaticplant invasion based on 28 plant traits and highlights the importanceof mitigating eutrophication to combat plant invasion. Eutrophication and exotic species invasion are key driversof theglobal loss of biodiversity and ecosystem functions in lakes. We selectedtwo exotic plants (Alternanthera philoxeroides and Myriophyllum aquaticum) and twonative plants (Myriophyllum spicatum and Vallisneria spinulosa) to elucidatethe effect of eutrophication on exotic plant invasiveness. We foundthat (1) elevated nutrient favored invasion of exotic species andinhibited growth of native plants. Species combinations and plantdensities of native plants had limited effects on the resistance toinvasion of the exotics. (2) A. philoxeroides featured the tightest connectivity among traits, which is consistentwith its high competitive ability. Although eutrophication causedphysiological stress to A. philoxeroides, it could effectively regulate enzyme activity and alleviate thestress. (3) M. aquaticum possessedstrong tolerance to habitat disturbance and was highly disruptiveto the surrounding plants. Eutrophication will exacerbate the adverseeffects of M. aquaticum on the littoralecosystem. (4) Nutrient enrichment reduced the biomass and relativegrowth rates of V. spinulosa and loweredphenolics and starch contents of M. spicatum, thereby making them more susceptible to habitat fluctuations. Overall,our study highlights how eutrophication alters the invasiveness ofexotic plants and the resistance of native plants in the littoralzone, which is of relevance in a world with intensified human activities.
关键词：
Africa;Asia;Cd;Cr;Cu;Europe;Fe;Fertilizer and pesticide use;Global pollution;Health risk;Heavy metal regulation;Lake pollution;Mining and manufacturing;Mn;Ni;North America;Pb;Pollution history;Pollution-control measure;River pollution;Rock weathering;Source apportionment;South America;Waste discharge;Zn
摘要：
Heavy metal pollution in surface water is a global environmental problem. This study analyzed the trends, health risks, and sources of eight dissolved heavy metal species in river and lake water across five continents (Africa, Asia, Europe, North America, and South America; Oceania was excluded owing to a lack of data) for the period 1970-2017. We wanted to assess the effects of various implemented countermeasures to pollution and to determine those that could be adopted worldwide. Collectively, the water system showed increasing trends for Cd, Cr, Cu, Ni, Mn, and Fe and decreasing trends for Pb and Zn. The mean dissolved concentrations of most heavy metals were highest in Asia and lowest in Europe. Most heavy metals had low non-carcinogenic risks over this period. The cancer risks associated with Pb were lower than the hazardous level on all five continents over the five decades, whereas the cancer risks related to Cr exceeded the hazardous level in the 1970s, 2000s, and 2010s, and in Africa, Asia, and North America over the entire period. Mining and manufacturing were consistently found to be critical sources of metal pollution from 1970 to 2017. However, the heavy metal sources differed significantly by continent, with waste discharge and rock weathering dominant in Africa; mining and manufacturing, along with rock weathering, are dominant in Asia and South America; fertilizer and pesticide use, along with rock weathering, are dominant in North America; and mining and manufacturing, waste discharge, and rock weathering are dominant in Europe. Global trends in the metal loadings in water and in relevant pollution-control measures suggest that countermeasures in Europe have successfully controlled heavy metal pollution. The successful measures include implementing rigorous standards for metal emissions, limiting the metal concentrations in products, and rigorously treating metal-contaminated waste. Therefore, the measures implemented in Europe should be extended worldwide to treat heavy metal pollution in water.
作者机构：
[吴爱平; 邹冬生; 李有志] Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China;[郑华] State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China;[张凯] College of Grassland and Environment Sciences, Xinjiang Agricultural University, Urumqi, 830052, China;[向丹] College of Resources and Environment, Qingdao Agricultural University, Qingdao，Shandong266109, China;[陈法霖] Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China, State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
通讯机构：
[Zheng, H.] S;State Key Laboratory of Urban and Regional Ecology, China
作者机构：
[边华林; 邓嘉俊; 李有志; 丁小慧; 姚欣; 周巧巧] College of Bioscience and Technology, Hunan Agricultural University, Changsha, 410128, China;[杨广军] Yueyang Research Institute of Forestry Science, Yueyang, 414000, China;[牛艳东] Hunan Academy of Forestry, Changsha, 410004, China
摘要：
Coastal wetlands are ecologically important all over the world, and they are relatively unstable with dramatic changes in aboveground vegetation. However, it is still unclear how the aboveground vegetation changes will influence the functioning of coastal wetland ecosystems, especially the decomposition processes. Here, we carried out a cotton strip experiment to examine the effects of Suaeda salsa community on the soil properties and the associated cellulose decomposition rates in the coastal wetlands of Liao River delta (NE China). Our results showed that S. salsa community significantly affected the contents of soil C, N, P, base cations, organic matter and the soil electrical conductivity (EC), and such effects might vary among different types or densities of aboveground vegetation. The soil cellulose decomposition rate (in terms of cotton strip tensile strength loss, CTSL) was slowed down when aboveground S. salsa communities are experiencing degradation or have been totally replaced by Phragmites australis communities. Moreover, there were positive partial correlations between soil N and CTSL, and between soil EC and CTSL, but a negative partial correlation between soil C and CTSL. Our results emphasized the importance of S. salsa community in determining the soil cellulose decomposition rate in this coastal region. The results suggest that vegetation degradation in coastal wetlands might lead to various changes in soil properties and hence affect other aspects of ecosystem functioning and services, especially nutrient cycling.
摘要：
Wetlands play a critical role in mitigating carbon emission. However, little is known about soil carbon emission and their environmental controls from inland floodplain wetlands. This study aimed to determine the effects of hydrologic and edaphic controllers (water table depth [WTD], soil temperature [Ts], and soil water content [SWC]) on soil C emission in Dongting Lake wetland, China. One-year emissions were measured in Carex meadow and mudflat using static chambers during 2013 to 2014, including nonflooded season (NFs) and flooded season (Fs). The results showed that soil C emission in the Carex meadow and mudflat was 307.8 and 264.3 g C·m−2·year−1, respectively, and 50–66% of soil C were emitted during NFs. Compared with NFs, CO2 emission was significantly decreased by 57% but CH4 emission was significantly increased by 38 times during Fs in the Carex meadow. Stepwise regression combined with structural equation model analysis showed that CO2 and CH4 flux were mainly influenced by Ts during NFs, and they were controlled by water temperature (Tw) during Fs. During NFs, CO2 flux increased with increasing Ts and SWC but decreased significantly when SWC was over 66% and 52% in the Carex meadow and mudflat, respectively. CH4 flux showed an emission pulse at SWC and Ts of 65% and 17.2 °C, respectively. These results indicate that flooding significantly inhibited soil CO2 emission but stimulated CH4 emission. The continuous decrease of flooding days caused by anthropogenic disturbances may induce soil C loss in Dongting Lake wetlands.
关键词：
Salix triandroides;Seasonal flooding;Morphological adaptation;Photosynthetic response;Anatomical adjustment;Dongting Lake wetlands
摘要：
A simulated flooding experiment was conducted to evaluate the effects of seasonal flooding on the plant Salix triandroides from the Dongting Lake wetlands in China. The morphology, photosynthetic activity, and anatomy of cuttings in three water conditions (−40 cm, water level 40 cm below soil surface; 0 cm, water level 0 cm at the soil surface; and 40 cm, water level 40 cm above soil surface) and two lights conditions (full sunlight and 10% sunlight) were measured. Plants had a higher survival ratio and biomass accumulation in full sunlight than in 10% sunlight when the water level was −40 and 0 cm, but there was no difference between these parameters in cuttings grown under the two light conditions in the 40 cm water treatment. In full sunlight, a lower survival ratio and reduced biomass were observed with increasing water level. The same trend was also seen for survival ratio in 10% sunlight. However, there was no difference in biomass among the three water levels in 10% sunlight, except for leaf weight. Branch height, leaf number, adventitious root length, and adventitious root number were different in the three water levels and two light conditions. In water levels of −40 and 0 cm, plants had lower chlorophyll contents in full sunlight than in 10% sunlight. In full sunlight, there was no difference in chlorophyll content between the water levels, while in 10% sunlight, lower chlorophyll content was observed in −40 cm than in 0 cm water. Photosynthetic rate, stomatal conductance, and transpiration rate decreased, but water-use efficiency increased in reduced light at all three water levels. Additionally, plants had higher porosity in 40 cm water than in −40 and 0 cm conditions. Based on the reduced plant growth in the 10% sunlight condition and decreased survival in the 40 cm water level, we conclude that low light significantly decreased plant acclimation to incomplete submergence and that high water levels induced dormancy in the cuttings. Therefore, the height of cuttings used for forestation or reforestation is an important consideration for mitigating the negative effects of seasonal flooding on the survival and growth of S. triandroides in Dongting Lake wetlands.
