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Fu H, Chen L, Ge Y, Wu A, Liu H, Li W, Yuan G, Jeppesen E. Linking human activities and global climatic oscillation to phytoplankton dynamics in a subtropical lake. WATER RESEARCH 2022; 208:117866. [PMID: 34800853 DOI: 10.1016/j.watres.2021.117866] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 11/07/2021] [Accepted: 11/09/2021] [Indexed: 06/13/2023]
Abstract
Human activities and climate change are two major stressors affecting lake ecosystems as well as phytoplankton communities worldwide. However, how the temporal dynamics of phytoplankton are directly or indirectly linked to anthropogenic activities and climatic oscillation remains unclear. We assessed the annual trends (1988-2018) in phytoplankton abundance (PA) in Lake Dongting, China and related it to five groups of variables characterizing human activities, global climate oscillation, water nutrients, hydrology, and meteorology. We found a significant increase in PA, urbanization (Upop), total nitrogen (TN), fertilizer application (FA), number of summer days (SU), and the warm speed duration index (WSDI) and a significant decrease in the water discharge of three inlets (TIWD) and the sediment discharge of three inlets (TISD) and four tributaries (FTSD) and the net sediment deposition (NSD). However, no significant annual trends were observed for the number of rainstorm days (R50mm), the simple precipitation intensity index (SDII) and yearly anomalies of El Niño-Southern oscillation events (ENSOi). Cross-correlation Function analyses demonstrated that the operation of the Three George Dam (TGD) strengthened the effects of hydrology, rainfall patterns and ENSOi on phytoplankton, but strongly weakened the association between water nutrients, human activities and phytoplankton abundance. Path analysis revealed that TP, TN, FA, R50 mm as well as WSDI had a direct positive effect on PA, while a direct negative effect was found for ENSOi, NSD and TISD. Human activities (Upop and FA), warming (WSDI and SU), and rainfall patterns (SDII and R50 mm) exerted indirect controls on phytoplankton through changes in water nutrients and hydrology. Climate change (ENSOi) had a direct effect on PA, but also showed twelve indirect pathways via changes in hydrology and meteorology (both positive and negative effects were found). Overall, meteorology contributed most markedly to the variations of PA (29.3%), followed by hydrology (25.3%), human activities (24%), water nutrients (10.5%), and ENSOi (1.9%). Our results highlight a strongly causal connection between human activities as well as global climate change and phytoplankton and the benefits of considering multiple environmental drivers in determining the temporal dynamics of lake biotic communities.
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Affiliation(s)
- Hui Fu
- Department of Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Resources and Environments, Hunan Agricultural University, Nongda Road 1#, Changsha 410128, PR China.
| | - Lidan Chen
- Department of Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Resources and Environments, Hunan Agricultural University, Nongda Road 1#, Changsha 410128, PR China
| | - Yili Ge
- Department of Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Resources and Environments, Hunan Agricultural University, Nongda Road 1#, Changsha 410128, PR China
| | - Aiping Wu
- Department of Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Resources and Environments, Hunan Agricultural University, Nongda Road 1#, Changsha 410128, PR China
| | - Huanyao Liu
- Department of Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Resources and Environments, Hunan Agricultural University, Nongda Road 1#, Changsha 410128, PR China
| | - Wei Li
- Research Institute of Ecology and Environmental Sciences, Nanchang Institute of Technology, Nanchang 330099, PR China
| | - Guixiang Yuan
- Department of Ecology, Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Resources and Environments, Hunan Agricultural University, Nongda Road 1#, Changsha 410128, PR China.
| | - Erik Jeppesen
- Department of Bioscience, Center for Water Technology, Aarhus University, Vejlsøvej 25, Silkeborg 8600, Denmark; Sino Danish Center for Education and Research, University of Chinese Academy of Sciences, Beijing, China; Limnology Laboratory, Department of Biological Sciences, Center for Ecosystem Research and Implementation, Middle East Technical University, Ankara, Turkey; Institute of Marine Sciences, Middle East Technical University, Erdemli, Mersin 33731, Turkey
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Drought-Modulated Boreal Forest Fire Occurrence and Linkage with La Nina Events in Altai Mountains, Northwest China. ATMOSPHERE 2020. [DOI: 10.3390/atmos11090956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Warming-induced drought stress and El Nino-associated summer precipitation failure are responsible for increased forest fire intensities of tropical and temperate forests in Asia and Australia. However, both effects are unclear for boreal forests, the largest biome and carbon stock over land. Here, we combined fire frequency, burned area, and climate data in the Altai boreal forests, the southmost extension of Siberia’s boreal forest into China, and explored their link with El Nino–Southern Oscillation (ENSO). Surprisingly, both summer drought severity and fire occurrence showed significant (p < 0.05) correlation with La Nina events of the previous year and therefore provide an important reference for forest fire prediction and prevention in Altai. Despite a significant warming trend, the increased moisture over Altai has largely offset the effect of warming-induced drought stress and led to an insignificant fire frequency trend in the last decades, resulting in largely reduced burned area since the 1980s. The reduced burned area can also be attributed to fire suppression efforts and greatly increased investment in fire prevention since 1987.
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