Abstract
Abstract: The objective of this work was to evaluate the ecosystem functions of a natural wetland and of artificially flooded rice areas, managed under organic and conventional systems, by phytomass degradation and by the colonization of this material by benthic macroinvertebrates. The experiment was carried out in a natural wetland area, and in two flooded rice areas managed under organic and conventional systems. Twenty-five decomposition bags filled with 10 g of dry vegetation were installed in each site. At 14, 28, 42, 56, and 70 days after the beginning of the experiment, five bags from each site were collected. Macroinvertebrates were identified and classified by functional trophic group. The number of species of benthic macroinvertebrates increased: natural wetland > organic system > conventional system. The Chironomidae group was present in all areas, confirming its food plasticity and adaptability to different substrates and environmental stress situations. The Amphipoda group was present only in the artificially flooded rice area, and the Acari, only in the natural wetland. The diversity of species in the natural wetland area was higher than in the artificially flooded rice area. Nutrient cycling, provided by phytomass decomposition, is affected by the management system, and the delay in this process causes a reduction of the ecosystem functions in the conventional system.
Highlights
IntroductionRemaining flooded rice straw and post-harvest sprouts (traditionally developed in rice regrowth, in the southern end of Rio Grande do Sul) are important as fodder for livestock (Monks et al, 2002)
Remaining flooded rice straw and post-harvest sprouts are important as fodder for livestock (Monks et al, 2002)
Benthic macroinvertebrates are responsible for sediment biorevolving, releasing nutrients into water, and accelerating the cycling process
Summary
Remaining flooded rice straw and post-harvest sprouts (traditionally developed in rice regrowth, in the southern end of Rio Grande do Sul) are important as fodder for livestock (Monks et al, 2002). Benthic macroinvertebrates are responsible for sediment biorevolving, releasing nutrients into water, and accelerating the cycling process They have an important role in the trophic dynamics, and constitute the link between the grower and the consumer, by performing filtering, fragmentation, and scraping of food, processing and converting it into phytomass available for other organisms, as well as assisting in the decomposition process (Nin et al, 2009; Oliveira & Callisto, 2010). These organisms are components of the biological diversity of natural as well as artificial wetlands, which include agroecosystems of flooded rice fields. Studies conducted in different regions have shown the biodiversity importance of soil organisms on the maintenance and distribution of other ecosystem services, which requires the understanding of occurrence patterns of these mechanisms, in different ecosystems, and the types of functional microorganisms (Bardgett & Putten, 2014; Handa et al, 2014)
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