Throughfall and Stemflow: The Crowning Headwaters of the Aquatic Carbon Cycle

Stubbins, Aron; Guillemette, François; Stan, John T. Van

doi:10.1007/978-3-030-29702-2_8

Cited by 17 publications

(24 citation statements)

References 79 publications

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“…TDN concentrations in throughfall (0.36 ± 0.29 mg‐N L −1 ) and stemflow (1.2 ± 0.9) were similar to those reported for cedar and oak trees in Georgia USA (∼5 mg‐N L −1 ) (Van Stan et al., 2017). Higher DOC concentrations in stemflow than throughfall may derive from increased contact time of water with tree surfaces and organic carbon sources combined with lower stemflow water yields (Stubbins et al., 2020). Although DOC and TDN concentrations were greater in stemflow than in throughfall, the DOC:TDN ratios were similar between the two flow paths (Figure 4c; median throughfall: ∼34, median stemflow: ∼35), an observation in agreement with DOC:TDN values reported by Van Stan et al.…”

Section: Discussionmentioning

confidence: 99%

“…Based upon dissolved organic matter quality, DOC in throughfall and stemflow likely derives from autochthonous (e.g., leaf, bark and epiphytic biota) and allochthonous sources (e.g., atmospheric deposition) deposited between storms (Stubbins et al., 2017). However, the influence of additional factors such as forest type and phenoseason on inter‐storm variability in DOC export and quality is not well studied (Stubbins et al., 2020; Van Stan et al., 2017). Low variability of the exponential decay model slopes ( c in Equation ) fit to DOC and TDN concentrations for both throughfall and stemflow suggests a shared process (e.g., dilution by rainfall) drives the variability in DOC export (Figure 5).…”

Section: Discussionmentioning

confidence: 99%

“…Within throughfall, dissolved organic carbon (DOC) comprises one of the largest solute fluxes by mass (McDowell et al., 2020) and is comparable to other important terrestrial carbon fluxes such as soil leaching and stream export (Stubbins et al., 2020). Concentrations of nitrogen species are also frequently elevated in throughfall and stemflow, although they are generally less enriched than DOC (Kristensen et al., 2004; Michalzik et al., 2001).…”

Section: Introductionmentioning

confidence: 99%

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Event Scale Relationships of DOC and TDN Fluxes in Throughfall and Stemflow Diverge From Stream Exports in a Forested Catchment

et al. 2021

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Estimating the transfer of terrigenous carbon and nutrients to aquatic systems remains a fundamental challenge for carbon cycle and ecosystem studies (Drake et al., 2018;Webster & Meyer, 1997). In order to predict how terrestrial and aquatic carbon budgets will respond to climate and land use change, an understanding of the processes controlling land and inland water carbon cycling is required (Tank et al., 2018). The first interactions between terrestrial carbon sources and water inputs to forested ecosystems occur within the tree canopy, which partitions precipitation into throughfall and stemflow. Throughfall is precipitation that falls on and through the canopy to the forest floor and typically comprises the largest fraction of incident precipitation (Levia & Frost, 2006). Stemflow is precipitation that flows along tree surfaces to the base of tree trunks and typically accounts for a lower percentage of total rainfall (<10%) in forests globally (Levia Abstract Aquatic fluxes of carbon and nutrients link terrestrial and aquatic ecosystems. Within forests, storm events drive both the delivery of carbon and nitrogen to the forest floor and the export of these solutes from the land via streams. To increase understanding of the relationships between hydrologic event character and the relative fluxes of carbon and nitrogen in throughfall, stemflow and streams, we measured dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) concentrations in each flow path for 23 events in a forested watershed in Vermont, USA. DOC and TDN concentrations increased with streamflow, indicating their export was limited by water transport of catchment stores. DOC and TDN concentrations in throughfall and stemflow decreased exponentially with increasing precipitation, suggesting that precipitation removed a portion of available sources from tree surfaces during the events. DOC and TDN fluxes were estimated for 76 events across a 2-year period. For most events, throughfall and stemflow fluxes greatly exceeded stream fluxes, but the imbalance narrowed for larger storms (>30 mm). The largest 10 stream events exported 40% of all stream event DOC whereas those same 10 events contributed 14% of all throughfall export. Approximately 2-5 times more DOC and TDN was exported from trees during rain events than left the catchment via streams annually. The diverging influence of event size on tree versus stream fluxes has important implications for forested ecosystems as hydrological events increase in intensity and frequency due to climate change. Plain Language SummaryRainfall over forests links carbon and nutrients on tree surfaces to the forest floor and streams. Rain falling through the canopy is called throughfall while water running down the tree trunk is called stemflow. The ultimate fate of throughfall and stemflow is uncertain. We measured carbon and nitrogen dissolved in throughfall, stemflow, and stream water during rain events in Vermont. We then used rain event size to estimate how much carbon and nitrogen were transported ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Event Scale Relationships of DOC and TDN Fluxes in Throughfall and Stemflow Diverge From Stream Exports in a Forested Catchment

et al. 2021

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“…Thus, stemflow may encounter a diverse array of organic and inorganic materials and, indeed, a diversity of solutes and particulates have been observed in stemflow in ecologically relevant amounts (Ponette-González et al, 2020). Dissolved organic carbon concentrations in stemflow, for example, represent some of the highest observations to-date in natural waters (Stubbins et al, 2020). The flux of nematodes and tardigrades within stemflow can be 10 5 individuals year −1 tree −1 , and even larger for rotifers, ∼10 6 individuals year −1 tree −1 (Ptatscheck et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Hypothesis and Theory: Fungal Spores in Stemflow and Potential Bark Sources

Magyar¹,

Stan²,

Sridhar³

2021

Front. For. Glob. Change

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The study of stemflow fungi began over 50 years ago. Past work has been performed in different climatic regions of the world, with different sampling methods, by mycologists focusing on different taxonomical groups. Therefore, we aim to synthesize this work to delineate major conclusions and emerging hypothesis. Here, we present: (1) a systematic compilation of observations on stemflow conidial concentration, flux, and species composition; (2) an evaluation of the methods underlying these observations; (3) a testable theory to understand spatiotemporal dynamics in stemflow (including honeydews) conidial assemblages, with a focus on their relationship to bark structure and microhabitats; and (4) a discussion of major hypotheses based on past observations and new data. This represents a knowledge gap in our understanding of fungal dispersal mechanisms in forests, in a spatially-concentrated hydrologic flux that interacts with habitats throughout the forest microbiome. The literature synthesis and new data represent observations for 228 fungal species’ conidia in stemflow collected from 58 tree species, 6 palm species, and 1 bamboo species. Hypothetical relationships were identified regarding stemflow production and conidial concentration, flux, and species composition. These relationships appear to be driven by bark physico-chemical properties, tree canopy setting, the diversity of in-canopy microenvironments (e.g., tree holes, bark fissures, and epiphytes), and several possible conidia exchange processes (teleomorph aerosols, epi-faunal exchanges, fungal colonization of canopy microhabitats, and droplet impacts, etc.). The review reveals a more complex function of stemflow fungi, having a role in self-cleaning tree surfaces (which play air quality-related ecoservices themselves), and, on the other hand, these fungi may have a role in the protection of the host plant.

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“…Stemflow can be highly enriched in a variety of solutes, including inorganic cations (e.g., K + , Na + , Ca 2+ , Mg 2+ , NH 4 + ), anions (e.g., Cl − , SO 2− , NO 3 − ) (Parker, 1983), and dissolved organic C (DOC: Stubbins et al, 2020). The chemical composition of stemflow can differ substantially among tree species and across forest settings (e.g., Limpert and Siegert, 2019;Liu et al, 2019;Su et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Bark Effects on Stemflow Chemistry in a Japanese Temperate Forest I. The Role of Bark Surface Morphology

Oka

Takahashi

Endoh

et al. 2021

Front. For. Glob. Change

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Stemflow can be an important pathway for the drainage of precipitation and related solutes through tree canopies to forest soils. As stemflow must drain along bark surfaces, the effects of bark structure on stemflow chemical composition is merited. This study examines the relationship between stemflow chemistry and bark surface structure for six species of varying bark morphology (four deciduous broadleaf trees and two evergreen coniferous trees) at a montane and an urban site in Japan. Stemflow from smooth-barked species contained greater concentrations of solutes that appear to be rinsed from the stem surface (i.e., sea salt aerosols); while, rougher-barked tree species contained greater or less concentrations of solutes that appear to be leached (e.g., Ca2+) or taken-up (e.g., inorganic N) by the bark, respectively. Site-specific atmospheric environments also influenced thee bark-stemflow chemistry relationships—where the greater elemental deposition in the urban plot generally resulted in greater stemflow chemistry than observed in the lower-deposition montane plot. Our results therefore suggest that the dynamics of dry deposition wash-off by stemflow, and the exchange of dissolved solutes between stemflow and the bark surface, are influenced by the surface structure of the bark and the site’s atmospheric environment. Therefore, the interactions between bark surface structure and its surrounding atmospheric environment are important factors in the stemflow-related elemental cycling between the tree and precipitation.

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Throughfall and Stemflow: The Crowning Headwaters of the Aquatic Carbon Cycle

Cited by 17 publications

References 79 publications

Event Scale Relationships of DOC and TDN Fluxes in Throughfall and Stemflow Diverge From Stream Exports in a Forested Catchment

Event Scale Relationships of DOC and TDN Fluxes in Throughfall and Stemflow Diverge From Stream Exports in a Forested Catchment

Hypothesis and Theory: Fungal Spores in Stemflow and Potential Bark Sources

Bark Effects on Stemflow Chemistry in a Japanese Temperate Forest I. The Role of Bark Surface Morphology

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