Patterns and bioavailability of soil nutrients and carbon across a gradient of inundation frequencies in a lowland river channel, Murray–Darling Basin, Australia

Woodward, K. Benjamin; Fellows, Christy Susan; Mitrovic, Simon M.; Sheldon, Fran

doi:10.1016/j.agee.2015.02.019

Cited by 25 publications

(21 citation statements)

References 46 publications

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“…The SMC‐2 site had an inset depositional floodplain at the floodzone location, whereas the SMC‐1 site is trapezoidal with relatively steep banks. Several studies have shown that periodic inundation can increase denitrification rates, due in large part to factors such as coupled nitrification‐denitrification, increases in organic carbon, and changes in nutrient availability [ Capps et al ., ; Shrestha et al ., ; Woodward et al ., ]. DeN rates at both the SMC‐1 and SMC‐2 floodzone locations were greater than rates for the in‐channel locations in August and October, and DEA rates at both floodzone locations were greater in June and August.…”

Section: Discussionmentioning

confidence: 95%

Environmental drivers of denitrification rates and denitrifying gene abundances in channels and riparian areas

Tomasek

Kozarek

Hondzo

et al. 2017

Water Resources Research

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Intensive agriculture in the Midwestern United States contributes to excess nitrogen in surface water and groundwater, negatively affecting human health and aquatic ecosystems. Complete denitrification removes reactive nitrogen from aquatic environments and releases inert dinitrogen gas. We examined denitrification rates and the abundances of denitrifying genes and total bacteria at three sites in an agricultural watershed and in an experimental stream in Minnesota. Sampling was conducted along transects with a gradient from always inundated (in‐channel), to periodically inundated, to noninundated conditions to determine how denitrification rates and gene abundances varied from channels to riparian areas with different inundation histories. Results indicate a coupling between environmental parameters, gene abundances, and denitrification rates at the in‐channel locations, and limited to no coupling at the periodically inundated and noninundated locations, respectively. Nutrient‐amended potential denitrification rates for the in‐channel locations were significantly correlated (α = 0.05) with five of six measured denitrifying gene abundances, whereas the periodically inundated and noninundated locations were each only significantly correlated with the abundance of one denitrifying gene. These results suggest that DNA‐based analysis of denitrifying gene abundances alone cannot predict functional responses (denitrification potential), especially in studies with varying hydrologic regimes. A scaling analysis was performed to develop a predictive functional relationship relating environmental parameters to denitrification rates for in‐channel locations. This method could be applied to other geographic and climatic regions to predict the occurrence of denitrification hot spots.

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Section: Discussionmentioning

confidence: 95%

Environmental drivers of denitrification rates and denitrifying gene abundances in channels and riparian areas

Tomasek

Kozarek

Hondzo

et al. 2017

Water Resources Research

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“…SMC1 had a traditional trapezoidal configuration, whereas SMC2 had an inset depositional floodplain at the floodzone location (Tomasek et al, 2017 ). Therefore, the floodzone location at SMC2 would have a larger reactive surface area, more sediment-water contact time, a larger hyporheic zone, and would likely favor greater rates of nitrogen cycling (McClain et al, 2003 ; Hefting et al, 2006 ; Wang et al, 2012 ; Woodward et al, 2015 ). Precipitation during the summer of 2014 occurred largely in one rain event in late June, whereas the rest of the summer was relatively dry.…”

Section: Discussionmentioning

confidence: 99%

Increased Denitrification Rates Associated with Shifts in Prokaryotic Community Composition Caused by Varying Hydrologic Connectivity

et al. 2017

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While modern developments in agriculture have allowed for increases in crop yields and rapid human population growth, they have also drastically altered biogeochemical cycles, including the biotransformation of nitrogen. Denitrification is a critical process performed by bacteria and fungi that removes nitrate in surface waters, thereby serving as a potential natural remediation strategy. We previously reported that constant inundation resulted in a coupling of denitrification gene abundances with denitrification rates in sediments, but these relationships were not maintained in periodically-inundated or non-inundated environments. In this study, we utilized Illumina next-generation sequencing to further evaluate how the microbial community responds to these hydrologic regimes and how this community is related to denitrification rates at three sites along a creek in an agricultural watershed over 2 years. The hydrologic connectivity of the sampling location had a significantly greater influence on the denitrification rate (P = 0.010), denitrification gene abundances (P < 0.001), and the prokaryotic community (P < 0.001), than did other spatiotemporal factors (e.g., creek sample site or sample month) within the same year. However, annual variability among denitrification rates was also observed (P < 0.001). Furthermore, the denitrification rate was significantly positively correlated with water nitrate concentration (Spearman's ρ = 0.56, P < 0.0001), denitrification gene abundances (ρ = 0.23–0.47, P ≤ 0.006), and the abundances of members of the families Burkholderiaceae, Anaerolinaceae, Microbacteriaceae, Acidimicrobineae incertae sedis, Cytophagaceae, and Hyphomicrobiaceae (ρ = 0.17–0.25, P ≤ 0.041). Prokaryotic community composition accounted for the least amount of variation in denitrification rates (22%), while the collective influence of spatiotemporal factors and gene abundances accounted for 37%, with 40% of the variation related to interactions among all parameters. Results of this study suggest that the hydrologic connectivity at each location had a greater effect on the prokaryotic community than did spatiotemporal differences, where inundation is associated with shifts favoring increased denitrification potential. We further establish that while complex interactions among the prokaryotic community influence denitrification, the link between hydrologic connectivity, microbial community composition, and genetic potential for biogeochemical cycling is a promising avenue to explore hydrologic remediation strategies such as periodic flooding.

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“…Clay content, soil moisture, and soil fertility were highly correlated with each other. Also, several nutrients are correlated with clay content, including major cations, CEC, N, and P (Schoenholtz et al 2000;Woodward et al 2015;Aprile and Lorandi 2019).…”

Section: Discussionmentioning

confidence: 99%

“…These forests may present large spatial variation, related to the distance from watercourses, topography, geomorphology, and internal processes (Rot et al 2000;Naiman et al 2005). In response to this heterogeneity, there may be large spatial variation in soil properties and composition of plant communities, which then contribute with spatial variation in processes such as nutrient and carbon cycling (Woodward et al 2015). Due to their ecological importance and strong deforesting pressure, the restoration of riparian forests has been stimulated worldwide (Hjältén et al 2016;Dybala et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Decomposition and stabilization of the organic matter in an old-growth tropical riparian forest: effects of soil properties and vegetation structure

Fernandes

Souza

Tanaka

et al. 2020

Preprint

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Background: Nutrient cycling in tropical forests has large importance for primary productivity, and decomposition of litterfall is a major process influencing nutrient balance in forest soils. Although large-scale factors strongly influence decomposition patterns, small-scale factors can have major influences, especially in old-growth forests that have high structural complexity and strong plant-soil correlations. Methods: We evaluated decomposition rates and stabilization of soil organic matter using the Tea Bag Index in an old-growth riparian forest in southeastern Brazil. We buried 50 pairs of green and red tea at two distances from the watercourse to evaluate the effects of forest structure and soil properties on decomposition processes. Forest structure and soil properties were described using Principal Components Analysis (PCA). The main axes for each analysis were considered predictors of decomposition processes using a structural equations model.Results: Decomposition rates presented a large variation among tea bags and were positively correlated with forest structure, as characterized by higher basal area, larger trees, and tree density. Higher decomposition rates were probably correlated with higher litter production and microbial activity. On the other hand, stabilization factor was related mainly to soil chemical properties, with higher values with increased soil fertility as indicated by the PCA axes. Further analyses evaluated the effects of clay content, soil moisture, soil organic matter, soil base saturation, and soil fertility as predictors of the stabilization factor. These predictors were highly correlated, but clay content was the best predictor, explaining 79% of the variation among plots. Conclusions: These results showed that this old-growth forest presented high heterogeneity in both forest structure and soil properties at small spatial scales, that influenced decomposition processes and contributed to small-scale variation in nutrient cycling. Heterogeneity in ecological processes can contribute to the resilience of old-growth forests, strengthening ecosystem functions such as nutrient cycling and carbon fixation, and highlighting the importance of restoration strategies focused in the recovery of ecosystem processes

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Patterns and bioavailability of soil nutrients and carbon across a gradient of inundation frequencies in a lowland river channel, Murray–Darling Basin, Australia

Cited by 25 publications

References 46 publications

Environmental drivers of denitrification rates and denitrifying gene abundances in channels and riparian areas

Environmental drivers of denitrification rates and denitrifying gene abundances in channels and riparian areas

Increased Denitrification Rates Associated with Shifts in Prokaryotic Community Composition Caused by Varying Hydrologic Connectivity

Decomposition and stabilization of the organic matter in an old-growth tropical riparian forest: effects of soil properties and vegetation structure

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