Muted responses to chronic experimental nitrogen deposition on the Colorado Plateau

Phillips, Michala L.; Winkler, Daniel E.; Reibold, Robin; Osborne, Brooke B.; Reed, Sasha C.

doi:10.1007/s00442-020-04841-3

Cited by 10 publications

(24 citation statements)

References 70 publications

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“…For example, N and P demand may have been higher in the finest‐textured site despite higher N and P concentrations due to higher ratios of C:nutrient availability. Regardless, our results align with prior work conducted along the same soil texture gradient, which demonstrated that, like these metrics, plant community composition (Phillips et al, 2021), seed bank communities (Haight et al, 2019) and plant–microbial interactions (Chung et al, 2017) differed with soil texture. Collectively, these findings show that conceptually binning dryland soils together as ‘sandy’ is potentially problematic because low levels of edaphic variability can be associated with meaningful differences in soil fertility and ecosystem function.…”

Section: Discussionsupporting

confidence: 90%

“…However, it is unlikely that such fluctuations or any unmeasured pools could account for a significant amount of N use or accumulation over the life span of the experiment. Prior work in these sites has shown a lack of N treatment effects on ecosystem properties like plant and microbial community structure and seed bank composition (Chung et al, 2017; Haight et al, 2019; McHugh et al, 2017; Phillips et al, 2021). Our work goes further to demonstrate that, not only is long‐term simulated N deposition insufficient to influence higher‐order ecosystem properties, but it has no cumulative effects on N availability, coupled biogeochemistry or other ecosystems processes in these sites.…”

Section: Discussionmentioning

confidence: 99%

“…We predicted that reactive N inputs would drive large, rapid changes in ecosystem structure and function, including wholesale changes to plant and microbial community composition. Instead, after 2 years, there were no N treatment effects on soil microbial community composition or diversity (McHugh et al, 2017) and, after 7 years, there were no N treatment effects on plant community structure or the abundance of the invasive annual grass Bromus tectorum (cheatgrass; Phillips et al, 2021). While some dryland studies have identified a similar lack of plant species response to N amendments in regions of the western U.S. that are removed from high N deposition sources (Ladwig et al, 2012), other dryland N fertilization experiments have identified significant changes in microbial biomass and metabolism (Sinsabaugh et al, 2015; Stursova et al, 2006), plant community structure and diversity (Allen et al, 2009; Brooks, 2003; Valliere et al, 2017; Zeng et al, 2010), and primary production (Báez et al, 2007; Yahdjian et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Biogeochemical and ecosystem properties in three adjacent semi‐arid grasslands are resistant to nitrogen deposition but sensitive to edaphic variability

et al. 2022

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1. Drylands have low nitrogen stocks and are predicted to be sensitive to modest increases in reactive nitrogen availability, but direct evidence that atmospheric nitrogen deposition will have sustained effects on dryland ecosystems is sparse and conflicting.2. We used three long-running in situ nitrogen deposition simulation experiments and a complementary laboratory incubation experiment to address fundamental questions about how nitrogen inputs affect drylands: (1) What are the long-and short-term consequences of nitrogen inputs for biogeochemical and ecosystem properties?; (2) Do these consequences depend on soil moisture availability?; and (3) Does soil texture modify the effects of nitrogen inputs and/or soil moisture availability? 3. In 2011, we established three study sites along a soil texture gradient in Arches National Park with plots receiving 0, 2, 5 or 8 kg N ha −1 annually (n = 5 per treatment per site). We assessed a suite of biogeochemical metrics over the long term and short term. To assess longer term effects, we sampled annually (2013)(2014)(2015)(2016)(2017)(2018)(2019), just prior to spring nitrogen fertilization. To assess short-term effects, we sampled immediately before and after spring nitrogen fertilization in 2013.Additionally, we compared foliar chemistry, soil extracellular enzyme activities, heterotrophic respiration rates, and nitrogen trace gas fluxes at select intervals during the study period (2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019). Finally, we conducted a laboratory incubation to measure the individual and interacting effects of soil moisture and nitrogen additions on soil microbial activity. 4. We identified some short-term effects in situ, but no lasting consequences of added nitrogen for any of the metrics measured. In the incubation, soil moisture treatments independently increased heterotrophic respiration rates but did not modify the effects of added nitrogen. In contrast to nitrogen treatments, soil texture was associated with large differences in biogeochemical cycling.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biogeochemical and ecosystem properties in three adjacent semi‐arid grasslands are resistant to nitrogen deposition but sensitive to edaphic variability

et al. 2022

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“…To address this important knowledge gap for drylands, and to use the low soil resource system as a testbed for hypotheses of multiple resource limitation, we evaluated how soil heterotrophic C cycling responded to inputs of water, C, N, and P individually and interactively on the Colorado Plateau. Previous work conducted at our study site found little detectable effect of long-term lowlevel N fertilization on soil biota or soil chemistry (McHugh et al, 2017;Phillips et al, 2021). Based on this lack of response, as well as previous work at a nearby site by Schaeffer and Evans (2005) that found that coadditions of C and N increased N immobilization compared to addition of N alone, we hypothesized that increases in multiple resources must co-occur for a significant response in the soil C cycle to occur.…”

Section: Introductionmentioning

confidence: 69%

“…For example, warmer temperatures and drier conditions are expected to reduce overall C cycling by reducing both soil respiration and photosynthesis, as well as subsequent C belowground inputs (Wertin et al, 2015(Wertin et al, , 2017. While atmospheric N deposition is relatively low on the Colorado Plateau (e.g., ~3 kg ha À1 year À1 ) and while at this site increased N inputs did not result in significant changes to plant communities (Phillips et al, 2021), slight increases in anthropogenic N fertilization associated with agriculture and industrial emissions (Vitousek et al, 1997) can increase risk of fire in some dryland communities due to increased growth of annual grasses, invasive species, and fuel layers (Perkins, 2010;Rao et al, 2010;Seabloom et al, 2021). Further, shifts in seasonal precipitation patterns (both reduced frequency and greater intensity) and prolonged drought conditions will likely have even stronger influence driving these limiting multi-resource processes, as could the interactions among these varied global change effects.…”

Section: Discussionmentioning

confidence: 92%

Multiple resource limitation of dryland soil microbial carbon cycling on the Colorado Plateau

Choi

Reed

Tucker

2022

Ecology

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Understanding interactions among biogeochemical cycles is increasingly important as anthropogenic alterations of global climate and of carbon (C), nitrogen (N), and phosphorus (P) cycles interactively affect the Earth system. Ecosystem processes in the dryland biome, which makes up over 40% of Earth's terrestrial surface, are often distinctively sensitive to small changes in resource availability, likely because levels of many resources are low. However, data also suggest that simultaneous changes in the availability of multiple resources may be necessary to affect a response in these low‐resource systems, offering an opportunity to test patterns and controls of co‐limitation, serial limitation, and individual limitation in soil environments. While drylands may play a governing role in key aspects of Earth's C cycle, and while an improved understanding of resource limitation could substantially improve our forecasts of dryland responses to change, our understanding of interacting controls on soil C cycle processes remains notably poor in these dry systems. Here, we address multiple fundamental hypotheses of resource controls over ecosystem function to test how water, C, N, and P regulate soil C cycling individually and interactively in a dryland ecosystem on the Colorado Plateau. Using a series of laboratory incubations, we found that, while water, C, and N limited C cycling through serial limitation, water alone resulted in an extremely small respiratory response from target organisms, whereas water + C resulted in a dramatic increase in soil C cycling, suggesting a degree of functional co‐limitation. Nitrogen additions alone resulted in no changes to soil C cycling, but when N was added in concert with water and C, N greatly increased soil C cycling rates relative to additions of water and C without N. Phosphorus additions had no effect on the C cycle either alone or synergistically. These patterns were consistent with the stoichiometry of the system and interactions among resources were surprising in ways that inform our understanding of critical theories in ecology, such as the Transient Maxima Hypothesis, supporting the suggestion that multiple resource limitation explains pulse‐dynamic C cycling in drylands better than water limitation alone.

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Effects of nitrogen addition on species composition and diversity of early spring herbs in a Korean pine plantation

Yang,

Zhang,

Jin

2023

Ecology and Evolution

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Under the background of global nitrogen deposition, temperate forest ecosystems are suffering increasing threats, and species diversity is gradually decreasing. In this study, nitrogen addition experiments were conducted on Korean pine (Pinus koraiensis) plantations in Northeast China to explore the effect of long‐term nitrogen addition on herb species diversity to test the following hypothesis: long‐term nitrogen addition further reduced plant species diversity by affecting plant growth, which may be due to soil acidification caused by excessive nitrogen addition. Experimental nitrogen addition was conducted from 2014 to 2021, and the nitrogen treatment levels were as follows: N0 (control treatment, 0/(kg N ha−1 year−1)), N20 (low nitrogen treatment, 20/(kg N ha−1 year−1)), N40 (medium nitrogen treatment, 40/(kg N ha−1 year−1)) and N80 (high nitrogen treatment, 80/(kg N ha−1 year−1)). A herb community survey was conducted in the region from 2015 to 2021. The results showed that long‐term nitrogen addition decreased soil pH, changed the species and composition of herbaceous plants, and decreased the species diversity of understory herbaceous plants. With the increase in nitrogen application years, middle‐ and high‐nitrogen treatments significantly reduced the diversity of early‐spring flowering herbs and early‐spring foliating herbs, and their diversity decreased with the decrease in soil pH, indicating that soil acidification caused by long‐term nitrogen addition may lead to the decrease of plant diversity. However, for early‐spring growing herbs, adequate nitrogen addition may promote their growth. Our results show that plants have evolved different life‐history strategies based on their adaptation mechanisms to the environment, and different life‐history strategies have different responses to long‐term nitrogen addition. However, for most plants, long‐term nitrogen application will have a negative impact on the growth and diversity of herbs in temperate forests.

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Muted responses to chronic experimental nitrogen deposition on the Colorado Plateau

Cited by 10 publications

References 70 publications

Biogeochemical and ecosystem properties in three adjacent semi‐arid grasslands are resistant to nitrogen deposition but sensitive to edaphic variability

Biogeochemical and ecosystem properties in three adjacent semi‐arid grasslands are resistant to nitrogen deposition but sensitive to edaphic variability

Multiple resource limitation of dryland soil microbial carbon cycling on the Colorado Plateau

Effects of nitrogen addition on species composition and diversity of early spring herbs in a Korean pine plantation

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