期刊
FUNCTIONAL ECOLOGY
卷 36, 期 9, 页码 2367-2383出版社
WILEY
DOI: 10.1111/1365-2435.14122
关键词
agriculture; benthic macroinvertebrates; biotic homogenization; consumer-resource; dominance; ecosystem function; land use; secondary production
类别
资金
- Brazilian National Council for Scientific and Technological Development [302280/2015-4, 305712/2018-7]
- CNPq
- Deutsche Forschungsgemeinschaft [BR 4358/1-1]
- Foundation for Research Support of the Federal State of Minas Gerais [CRA PPM 00596-16, CRA-11/12]
Agricultural land-use has various impacts on stream ecosystems, including nutrient and pesticide contamination, riparian clear-cutting, and hydromorphological degradation. These changes affect the abiotic environment and direct productivity of macroinvertebrate communities. Additionally, biological mechanisms such as species interactions, richness, competition, and predation indirectly affect macroinvertebrate productivity. This study found that agricultural streams had higher macroinvertebrate secondary production, biomass, and density compared to forested streams. This was associated with higher nutrient concentrations, riparian herbaceous vegetation, organic carbon, and chlorophyll-a concentrations in agricultural streams. Species richness and evenness were lower in agricultural streams, indicating density compensation and trait dominance as the mechanisms for higher productivity. The study emphasizes the importance of preserving riparian vegetation and limiting nutrient contamination in stream ecosystems.
Agricultural land-use affects the environmental and biological characteristics of stream ecosystems through multiple pathways including nutrient and pesticide contamination, riparian clear-cutting and hydromorphological degradation. These changes in the abiotic environment can have a direct effect on the productivity of macroinvertebrate communities through environmental filtering and via altered resource conditions encompassing a shift from allochthonous to autochthonous primary production and changes in elemental stoichiometry and food quality. Additionally, macroinvertebrate productivity can be affected indirectly via biological mechanisms, such as changes in species interactions, richness, competition, and predation. We studied the effects of agriculture on structural and functional descriptors of macroinvertebrate communities by assessing environmental characteristics and macroinvertebrate secondary production (MSP), biomass and density in two forested and two agricultural streams and investigated underlying biotic mechanisms. On average, MSP was 1.6-3.6, biomass 2.8-6.2 and density 5-13 times higher in agricultural than in forested streams. This pattern was associated with higher nutrient concentrations, standing crops of riparian herbaceous vegetation, suspended particulate organic carbon, quantity and quality of epilithic biofilms and chlorophyll-a concentrations in seston and biofilm of the agricultural streams. Species richness and evenness were significantly lower in agricultural than in forested streams. A negative relationship between MSP and species richness and evenness indicated that density compensation and trait dominance were the prevalent mechanisms facilitating higher MSP in agricultural streams. Our findings suggest that the loss of riparian canopy and excess nutrient conditions are the major environmental drivers contributing to homogenization of ecological niches and dominance of highly productive non-insect generalist species. This study highlights the importance of an ecosystem approach to understanding how complex aggregate stressors affect the regulation of consumer-resource interactions. There is an urgent need to preserve or restore natural riparian vegetation, fostering habitat and resource diversity and limiting nutrient contamination to stream ecosystems. Read the free Plain Language Summary for this article on the Journal blog.
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