Investigating Microtopographic and Soil Controls on a Mountainous Meadow Plant Community Using High‐Resolution Remote Sensing and Surface Geophysical Data

Falco, Nicola; Wainwright, Haruko M.; Dafflon, Baptiste; Léger, Emmanuel; Peterson, John; Steltzer, Heidi; Wilmer, C.; Rowland, J. C.; Williams, Kenneth H.; Hubbard, Susan S.

doi:10.1029/2018jg004394

Cited by 28 publications

(55 citation statements)

References 76 publications

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“…We chose this transect because these ecosystem types are representative of dominant land cover adjacent to the East River. Vegetation in the Hillslope is a mix of perennial bunchgrasses (e.g., Festuca arizonica), forbs (e.g., Lupinus spp., Potentilla gracilis, Veratrum californicum), and shrubs (Artemisia tridentata), whereas plant communities in the Floodplain are dominated by dwarf birch (Betula grandulosa) and mountain willow (Salix monticola, Falco et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

“…For example, although earlier snowmelt could result in an earlier pulse of N released from the crash in microbial biomass, floodplain ecosystems may buffer ecosystem N losses via well-coupled plant-mycorrhizal N uptake in spring. It may also be possible to predict the capacity of other watershed locations to retain N in response to earlier snowmelt based upon plant distributions and plant-mycorrhizae associations, given that plant species assemblages and plantmycorrhizal associations can be mapped and inferred at high spatial resolution using remote-sensing methods (Fisher et al, 2016;Falco et al, 2019).…”

Section: Spring Nitrogen Dynamics and Spring-adapted Bacteria And Fungimentioning

confidence: 99%

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The Snowmelt Niche Differentiates Three Microbial Life Strategies That Influence Soil Nitrogen Availability During and After Winter

et al. 2020

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Soil microbial biomass can reach its annual maximum pool size beneath the winter snowpack and is known to decline abruptly following snowmelt in seasonally snow-covered ecosystems. Observed differences in winter versus summer microbial taxonomic composition also suggests that phylogenetically conserved traits may permit winter-versus summer-adapted microorganisms to occupy distinct niches. In this study, we sought to identify archaea, bacteria, and fungi that are associated with the soil microbial bloom overwinter and the subsequent biomass collapse following snowmelt at a high-altitude watershed in central Colorado, United States. Archaea, bacteria, and fungi were categorized into three life strategies (Winter-Adapted, Snowmelt-Specialist, Spring-Adapted) based upon changes in abundance during winter, the snowmelt period, and after snowmelt in spring. We calculated indices of phylogenetic relatedness (archaea and bacteria) or assigned functional attributes (fungi) to organisms within life strategies to infer whether phylogenetically conserved traits differentiate Winter-Adapted, Snowmelt-Specialist, and Spring-Adapted groups. We observed that the soil microbial bloom was correlated in time with a pulse of snowmelt infiltration, which commenced 65 days prior to soils becoming snow-free. A pulse of nitrogen (N, as nitrate) occurred after snowmelt, along with a collapse in the microbial biomass pool size, and an increased abundance of nitrifying archaea and bacteria (e.g., Thaumarchaeota, Nitrospirae). Winter-and Spring-Adapted archaea and bacteria were phylogenetically clustered, suggesting that phylogenetically conserved traits allow Winter-and Spring-Adapted archaea and bacteria to occupy distinct niches. In contrast, Snowmelt-Specialist archaea and bacteria were phylogenetically overdispersed, suggesting that the key mechanism(s) of the microbial biomass crash are likely to be density-dependent (e.g., trophic interactions, competitive exclusion) and affect organisms across a broad phylogenetic spectrum. Saprotrophic fungi were the dominant functional group across fungal life strategies, however, ectomycorrhizal

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Section: Methodsmentioning

confidence: 99%

Section: Spring Nitrogen Dynamics and Spring-adapted Bacteria And Fungimentioning

confidence: 99%

The Snowmelt Niche Differentiates Three Microbial Life Strategies That Influence Soil Nitrogen Availability During and After Winter

et al. 2020

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“…For example, although earlier snowmelt could result in an earlier pulse of N released from the crash in microbial biomass, floodplain ecosystems may buffer ecosystem N losses via well-coupled plant-mycorrhizal N uptake in spring. It may also be possible to predict the capacity of other watershed locations to retain N in response to earlier snowmelt based upon plant distributions and plant-mycorrhizae associations, given that plant species assemblages and plant-mycorrhizal associations can be mapped and inferred at high spatial resolution using remote-sensing methods (Fisher et al 2016, Falco et al 2019).…”

Section: Discussionmentioning

confidence: 99%

“…We chose this transect because these ecosystem types are representative of dominant land cover adjacent to the East River. Vegetation in the Hillslope is a mix of perennial bunchgrasses (e.g., Festuca arizonica ), forbs (e.g., Lupinus spp., Potentilla gracilis, Veratrum californicum ), and shrubs ( Artemesia tridentata ), whereas plant communities in the Floodplain are dominated by dwarf birch ( Betula grandulosa ) and mountain willow ( Salix monticola (Falco et al 2019)).…”

Section: Methodsmentioning

confidence: 99%

The snowmelt niche differentiates three microbial life strategies that influence soil nitrogen availability during and after winter

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et al. 2020

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28Soil microbial biomass can reach its annual maximum pool size beneath the winter 29 snowpack and is known to decline abruptly following snowmelt in seasonally snow-covered 30 ecosystems. Observed differences in winter versus summer microbial taxonomic composition 31 also suggests that phylogenetically conserved traits may permit winter-versus summer-adapted 32 microorganisms to occupy distinct niches. In this study, we sought to identify archaea, bacteria, 33 and fungi that are associated with the soil microbial bloom overwinter and the subsequent 34 biomass collapse following snowmelt at a high-altitude watershed in central Colorado, USA. 35 Archaea, bacteria, and fungi were categorized into three life strategies (Winter-Adapted, 36 Snowmelt-Specialist, Spring-Adapted) based on changes in abundance during winter, the 37 snowmelt period, and after snowmelt in spring. We calculated indices of phylogenetic 38 relatedness (archaea and bacteria) or assigned functional attributes (fungi) to organisms within 39 life strategies to infer whether phylogenetically conserved traits differentiate Winter-Adapted, 40 Snowmelt-Specialist, and Spring-Adapted groups. We observed that the soil microbial bloom 41 was correlated in time with a pulse of snowmelt infiltration, which commenced 65 days prior to 42 soils becoming snow-free. A pulse of nitrogen (N, as nitrate) occurred after snowmelt, along 43 with a collapse in the microbial biomass pool size, and an increased abundance of nitrifying 44 archaea and bacteria (e.g., Thaumarchaeota, Nitrospirae). Winter-and Spring-Adapted archaea 45 and bacteria were phylogenetically clustered, suggesting that phylogenetically conserved traits 46 allow Winter-and Spring-Adapted archaea and bacteria to occupy distinct niches. In contrast, 47Snowmelt-Specialist archaea and bacteria were phylogenetically overdispersed, suggesting that 48 the key mechanism(s) of the microbial biomass crash are likely to be density-dependent (e.g., 49trophic interactions, competitive exclusion) and affect organisms across a broad phylogenetic 50 3 spectrum. Saprotrophic fungi were the dominant functional group across fungal life strategies, 51 however, ectomycorrhizal fungi experienced a large increase in abundance in spring. If well-52 coupled plant-mycorrhizal phenology currently buffers ecosystem N losses in spring, then 53 changes in snowmelt timing may alter ecosystem N retention potential. Overall, we observed that 54 the snowmelt separates three distinct soil niches that are occupied by ecologically distinct groups 55 of microorganisms. This ecological differentiation is of biogeochemical importance, particularly 56 with respect to the mobilization of nitrogen during winter, before and after snowmelt. 57 58 59

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“…This watershed is the location of the Watershed Function Scientific Focus Area (SFA) led by Lawrence Berkeley National Laboratory (Hubbard et al, ). Sediment samples were collected from the floodplain of a meandering reach of the East River (Lower Montane Floodplain site) at an elevation of 2,760 m. The floodplain valley is approximately 200 m wide in this location, with the river meandering across nearly the entire valley (Falco et al, ; Wainwright & Williams, ). Sediments were collected along transects across an active (Meander C) and cutoff (Meander O/oxbow) meander (Figure ) in September 2016 and July 2016, respectively.…”

Section: Methodsmentioning

confidence: 99%

Shale as a Source of Organic Carbon in Floodplain Sediments of a Mountainous Watershed

et al. 2020

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Shales contain high levels of organic carbon (OC) and represent a large fraction of the Earth's reduced carbon stocks. While recent evidence suggests that shale‐derived OC may be actively cycled in riverine systems, this process is poorly understood and not currently considered in global C models. Through the use of sediment density fractionations, extractions, radiocarbon measurements, and chemical characterization, we provide information on the abundance, chemistry, and mobility of shale‐derived OC in floodplain sediments of a shale‐rich mountainous watershed. The heavy fraction of the sediment, representing mineral‐associated OC, is the largest (84 ± 6% of TOC) and oldest (Δ14C values −224 to −853‰) OC pool. Evidence of shale‐derived OC is observed in all sediment C pools (i.e., occluded light fraction, water‐soluble, and pyrophosphate‐extractable) except the free light fraction, which is entirely modern. Relatively consistent chemistry was observed across samples for extracted and density‐separated OC, despite wide ranges of Δ14C values. Carbon spectroscopy revealed that floodplain sediments had a higher degree of functionalized aromatic groups and lower carbonate content compared to shale collected nearby, consistent with chemical alteration and mixing with other C sources in the floodplain. We estimate that approximately 23–34% of sediment OC is derived from shale, with implications for other shale‐derived elements (e.g., N). This study demonstrates the important contribution of shale‐OC, particularly in environments with low litter inputs. The large impact of radiocarbon‐dead shale‐OC, which has a thermally altered chemical structure distinct from plant litter, on Δ14C values and reactivity of sediment‐OC must be considered.

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Investigating Microtopographic and Soil Controls on a Mountainous Meadow Plant Community Using High‐Resolution Remote Sensing and Surface Geophysical Data

Cited by 28 publications

References 76 publications

The Snowmelt Niche Differentiates Three Microbial Life Strategies That Influence Soil Nitrogen Availability During and After Winter

The Snowmelt Niche Differentiates Three Microbial Life Strategies That Influence Soil Nitrogen Availability During and After Winter

The snowmelt niche differentiates three microbial life strategies that influence soil nitrogen availability during and after winter

Shale as a Source of Organic Carbon in Floodplain Sediments of a Mountainous Watershed

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