Biological nitrogen fixation across major biomes in Latin America: Patterns and global change effects

Reis, Carla Roberta Gonçalves; Pacheco, F.; Reed, Sasha C.; Tejada, Graciela; Nardoto, Gabriela Bielefeld; Forti, M. C.; Ometto, Jean Pierre

doi:10.1016/j.scitotenv.2020.140998

Cited by 25 publications

(16 citation statements)

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“…In addition to symbiotic (rhizobial and actinorhizal) associations with vascular plants, BNF occurs in many niches (ecosystem compartments) even within a single biome including bulk soil, plant rhizospheres, decaying wood and roots, leaf litter, biological soil crusts, inside/on the surface of roots or above-ground plant tissues, in association with lichens and bryophytes, in the colonies and guts of insects and animals, and on snow and ice, and new examples emerge regularly (Cleveland et al, in review;Reed et al, 2011). While symbiotic inputs can be extremely high in certain cases, free-living niches can represent the dominant BNF input in ecosystems as diverse as tropical forests, boreal forests and pine savannas (DeLuca et al, 2002;Reis et al, 2020;Tierney et al, 2019). Spatially, the distribution of niches spans a gamut from highly discrete (symbiotic root nodules and lichens) to continuous (bulk soil), superimposed with vertical gradients such as soil depth or canopy position.…”

Section: Bnf Nichesmentioning

confidence: 99%

A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems

et al. 2021

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1. Accurately quantifying rates and patterns of biological nitrogen fixation (BNF) in terrestrial ecosystems is essential to characterize ecological and biogeochemical interactions, identify mechanistic controls, improve BNF representation in conceptual and numerical modelling, and forecast nitrogen limitation constraints on future carbon (C) cycling.2. While many resources address the technical advantages and limitations of different methods for measuring BNF, less systematic consideration has been given to the broader decisions involved in planning studies, interpreting data, and extrapolating results. Here, we present a conceptual and practical road map to study design, study execution, data analysis and scaling, outlining key considerations at each step.3. We address issues including defining N-fixing niches of interest, identifying important sources of temporal and spatial heterogeneity, designing a sampling scheme (including method selection, measurement conditions, replication, and consideration of hotspots and hot moments), and approaches to analysing, scaling and reporting BNF. We also review the comparability of estimates derived using different approaches in the literature, and provide sample R code for simulating symbiotic BNF data frames and upscaling.4. Improving and standardizing study design at each of these stages will improve the accuracy and interpretability of data, define limits of extrapolation, and facilitate broader use of BNF data for downstream applications. We highlight aspects-such as quantifying scales of heterogeneity, statistical approaches for dealing with nonnormality, and consideration of rates versus ecological significance-that are ripe for further development. | 1123Methods in Ecology and Evoluঞon SOPER Et al.

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Section: Bnf Nichesmentioning

confidence: 99%

A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems

et al. 2021

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“…Nevertheless, even in ecosystems with an abundance of N 2 -fixing plants such as the ecosystems in the current study or other studies (Reis et al, 2020;Sullivan et al, 2014;Taylor et al, 2019), FNF may exceed SNF in some cases. For example, FNF rates were twofold higher than SNF rates in both moist and dry forests in Latin America (Reis et al, 2020). This is largely due to the ubiquitous distribution of free-living diazotrophs but huge variation of both nodulation and nitrogenase activity in nodule (Sullivan et al, 2014).…”

Section: Contribution Of Symbiotic and Free-living Forms To Total N 2 Fixationmentioning

confidence: 56%

“…In ecosystems of higher latitudes, the contribution of SNF to total N 2 fixation would be lower due to lower abundance of N 2 -fixing plants (Menge et al, 2017;Wang & Houlton, 2009). Nevertheless, even in ecosystems with an abundance of N 2 -fixing plants such as the ecosystems in the current study or other studies (Reis et al, 2020;Sullivan et al, 2014;Taylor et al, 2019), FNF may exceed SNF in some cases. For example, FNF rates were twofold higher than SNF rates in both moist and dry forests in Latin America (Reis et al, 2020).…”

Section: Contribution Of Symbiotic and Free-living Forms To Total N 2 Fixationmentioning

confidence: 60%

“…The reported SNF and FNF rates for temperate and tropical ecosystems varied from 0.1 to 160 kg N ha −1 yr −1 and 0.01–60 kg N ha −1 yr −1 , respectively, based on limited measurements (Davidson et al., 2018; Reed et al., 2011; Reis et al., 2020; Sullivan et al., 2014). The rates of both SNF (1.97–41.60 kg N ha −1 yr −1 ) and FNF (5.07–20.33 kg N ha −1 yr −1 ) in the current study are well within the reported ranges.…”

Section: Discussionmentioning

confidence: 99%

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Symbiotic and Free‐Living N₂ Fixation in Subtropical Pueraria lobata Communities of Southwest China

Zhou

2021

JGR Biogeosciences

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Biological N 2 fixation (or N 2 fixation hereafter), the process that converts atmospheric N 2 to ammonia by diazotrophs with the catalysis of nitrogenase, is one major pathway of new nitrogen (N) inputs for terrestrial ecosystems (Vitousek et al., 2013). N 2 fixation can be classified into symbiotic N 2 fixation (SNF hereafter) and free-living N 2 fixation (FNF hereafter) (Reed et al., 2011). For SNF, the diazotrophs are symbiotically related to host plants by forming nodules, which are specialized for N 2 fixation, and the other types are classified as FNF, including N 2 fixation carried out by free-living diazotrophs in soil (soil FNF hereafter), litter, foliage, moss, and lichen (Reed et al., 2011). Due to limited field measurements and poor understanding of the underlying mechanisms, there is a huge uncertainty in N 2 fixation estimates for global terrestrial natural ecosystems with current estimates ranging from 40 to 290 Tg N yr −1 (Cleveland et al., 1999;Davies-Barnard & Friedlingstein, 2020;Vitousek et al., 2013). According to the existing limited measurements for terrestrial natural ecosystems, SNF rates vary between 0.1 and 160 kg N ha −1 yr −1 , and the FNF rates range from 0.01 to 60 kg N ha −1 yr −1 (Reed et al., 2011). However, few studies have simultaneously measured SNF and FNF rates within the same ecosystem. According to a model analysis, FNF contributes a smaller fraction to total N 2 fixation in the tropical region (17%) and the other regions (44%) (Wang & Houlton, 2009). However, recent evidence shows that FNF is equally important as or may exceed SNF in some secondary and Abstract Biological N 2 fixation plays crucial roles in determining the pattern and pace of ecological succession and carbon sequestration. Nevertheless, the rates and controls of symbiotic (SNF) and freeliving (FNF) N 2 fixation have rarely been investigated simultaneously. Here we measured SNF and soil FNF rates for eight early succession ecosystems dominated by kudzu (Pueraria lobata (Willd.) Ohwi) in a subtropical region of China in growing and nongrowing seasons. N 2 fixation rates were measured using acetylene reduction assay against a 15 N 2 uptake method. Both SNF and soil FNF rates were significantly higher in the growing season than in the nongrowing season. The two forms of N 2 fixation contributed equally to total N 2 fixation rate across the eight sites with soil FNF being higher than SNF in half of the sites. Total N 2 fixation rates ranged from 7.12 to 61.93 kg N ha −1 yr −1 with an average of 22.93 ± 6.52 kg N ha −1 yr −1 . N 2 fixation contributed significantly to soil nitrogen and carbon accumulation. Both SNF and FNF were significantly related to soil moisture. Additionally, SNF and soil FNF were strongly correlated with phosphorus availability and vanadium/iron availability, respectively, most likely implying that SNF was limited by phosphorus and soil FNF was limited by vanadium or iron. Our findings suggest that SNF and soil FNF may be limited by different sets of nutrients within an ecosystem.Plain L...

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“…Nitrogen fixation by free‐living bacteria often includes N 2 fixation by bacteria associated with bryophytes (mosses and liverworts). Yet, studies on bryophyte‐associated N 2 fixation in tropical forests are sparse (Cusack et al, 2009; Reis et al, 2020; Zheng et al, 2020), and in particular, studies in TMCF are, to our knowledge, even rarer (Markham & Fernández Otárola, 2021; Matzek & Vitousek, 2003).…”

Section: Introductionmentioning

confidence: 99%

High nitrogen‐fixing rates associated with ground‐covering mosses in a tropical mountain cloud forest will decrease drastically in a future climate

et al. 2022

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1. Tropical mountain cloud forests (TMCF) harbour a high bryophyte (mosses and liverworts) biomass and diversity. Furthermore, the high air humidity makes these forests well suited for bryophyte-associated nitrogen (N 2 ) fixation by cyanobacteria, providing a potentially important source of N input to the ecosystem. However, few studies have assessed bryophyte-associated N input in these ecosystems, and these have focused on epiphytic bryophytes, whereas abundant ground-covering bryophytes have not been included.2. In this study, we quantified N 2 fixation rates associated with bryophytes, focusing on ground-covering mosses in a neotropical mountain cloud forest. Furthermore, we identified the effects of climate change (higher temperature 10 vs. 20° and lower bryophyte moisture level 50% vs. 100%) on N 2 fixation across bryophyte species and groups (mosses and liverworts).3. Nitrogen fixation rates associated with ground-covering moss species were up to 2 kg N ha −1 year −1 , which is comparable to other N inputs (e.g. N deposition) in tropical cloud forests. Furthermore, changes in temperature showed little effect on N 2 fixation, but low moisture levels significantly suppressed N 2 fixation activity. We found low N 2 fixation activity associated with the investigated liverworts. 4. Our results demonstrate the importance of ground-covering, moss-associated N 2 fixation as a N source in tropical cloud forests and suggest that predicted future declines in precipitation in these systems will reduce N inputs from bryophyte-associated cyanobacteria.

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Biological nitrogen fixation across major biomes in Latin America: Patterns and global change effects

Cited by 25 publications

References 131 publications

A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems

A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems

Symbiotic and Free‐Living N₂ Fixation in Subtropical Pueraria lobata Communities of Southwest China

High nitrogen‐fixing rates associated with ground‐covering mosses in a tropical mountain cloud forest will decrease drastically in a future climate

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Biological nitrogen fixation across major biomes in Latin America: Patterns and global change effects

Cited by 25 publications

References 131 publications

A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems

A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems

Symbiotic and Free‐Living N2 Fixation in Subtropical Pueraria lobata Communities of Southwest China

High nitrogen‐fixing rates associated with ground‐covering mosses in a tropical mountain cloud forest will decrease drastically in a future climate

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Symbiotic and Free‐Living N₂ Fixation in Subtropical Pueraria lobata Communities of Southwest China