Temporal Variability of Soil Respiration in Experimental Tree Plantations in Lowland Costa Rica

Raich, James W.

doi:10.3390/f8020040

Cited by 20 publications

(20 citation statements)

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“…In addition, although small in magnitude, their observed diel patterns were apparently driven by fluctuations in soil moisture rather than temperature (Rubio & Detto, 2017). Other studies have found relationships with soil temperature similar to ours (Meir et al, 1996; Raich, 2017; Zanchi et al, 2014), although hysteresis was also evident suggesting other potential controls in addition to temperature on diel variation of soil respiration (Raich, 2017; Rubio & Detto, 2017; Vargas & Allen, 2008a; Zanchi et al, 2014).…”

Section: Discussionsupporting

confidence: 83%

“…Our high frequency measurements using automated chambers revealed significant diel variation of soil respiration in this tropical moist forest throughout a 3‐year period. Results from prior studies investigating soil respiration on this time scale in other tropical forests have been mixed, with some studies reporting significant diel variation of soil respiration (Lugo et al, 2008; Medina, 1969; Medina et al, 1980; Meir et al, 1996;Raich, 2017 ; Rubio & Detto, 2017 ; Vargas & Allen, 2008a ; Zanchi et al, 2014), and others reporting relatively consistent soil respiration values throughout the day (Davidson et al, 2000; Doughty & Goulden, 2008; Giardina & Ryan, 2002; Goulden et al, 2004; Litton et al, 2011; Salimon et al, 2004; Schwendenmann et al, 2003; Trumbore et al, 1995; Wood et al, 2013). The lack of significant variation of soil respiration at diel time scales in tropical forests could be a consequence of insufficient sampling frequency—a common limitation of soil respiration studies conducted in the tropics.…”

Section: Discussionmentioning

confidence: 99%

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Significant Diel Variation of Soil Respiration Suggests Aboveground and Belowground Controls in a Tropical Moist Forest in Puerto Rico

Arroyo

Wood

2020

JGR Biogeosciences

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Soil respiration in tropical forests represents a major source of carbon dioxide (CO2) to the atmosphere. The magnitude of this large flux is projected to change in response to climate change, with global implications due to the disproportionate role of tropical forests in the carbon cycle. Evaluating diel patterns of soil respiration concomitantly with biophysical drivers is a valuable approach for elucidating the mechanisms controlling soil respiration. We measured hourly soil respiration rates in a tropical moist forest in Puerto Rico over a 3‐year period using automated chambers, as well as soil temperature/moisture, air temperature, relative humidity, and photosynthetically active radiation. Hourly soil respiration exhibited as much as threefold variation on diel time scales (monthly diel amplitude ranged from 1 to 7 μmol CO2 m−2 s−1), and both the magnitude and shape of diel patterns changed significantly from month to month. Soil respiration peaked in the morning and late afternoon with a midday decline that was evident during the warmest summer months. The relationship between soil respiration and soil temperature differed during daytime versus the night, with a nonlinear relationship in the daytime but a significant positive linear relationship at night. These findings suggest factors other than/in addition to temperature could be controlling soil respiration during the day; however, soil respiration did not correlate with any of the other measured biophysical variables. Overall, our results highlight the potential role of aboveground processes as drivers of soil respiration at diel time scales, especially in closed canopy tropical forests with low diel variation in soil temperature/moisture.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Significant Diel Variation of Soil Respiration Suggests Aboveground and Belowground Controls in a Tropical Moist Forest in Puerto Rico

Arroyo

Wood

2020

JGR Biogeosciences

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“…We found the month‐to‐month R S CV distribution to be relatively higher (median of 26%, Figure ) than the CV at shorter time scales. This is expected as months are disconnected from the predictable cyclic daily and annual temperature and moisture cycles that drive R S (Raich, ); but it has significant sampling implications given the popularity of monthly sampling. Our sampling requirement numbers (Table ) are largely consistent with the results of Jian, Steele, Thomas, Day, and Hodges (), who found (for deciduous forests, Table in that study) that 183 measurements were required to be 95% certain of being within 10% of the true mean, and 9 measurements to be 80% certain of being within 30%.…”

Section: Discussionmentioning

confidence: 99%

Soil Respiration Variability and Correlation Across a Wide Range of Temporal Scales

et al. 2019

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The high temporal variability of the soil-to-atmosphere CO 2 flux (soil respiration, R S ) has been studied at hourly to multiannual time scales but remains less well understood than R S spatial variability. How R S fluxes vary and are autocorrelated at various time lags has practical implications for sampling and more fundamentally for our understanding of its abiotic and biotic underlying mechanisms. We examined the variability, correlation, and sampling requirements of R S over a wide range of temporal scales in a temperate deciduous forest in eastern Maryland, USA, using both automated (temporally continuous, N = 30,036 over 10 months) and survey (spatially diverse, temporally sparse, N = 1,912 over 17 months) data. Data from a global R S database were also used to examine interannual variability in comparable forests. The coefficient of variability of successive measurements generally varied from the minute (median coefficient of variation 16%) to hourly and daily (11-12%) time scales. Successive R S values measured at a given collar exhibited a strong hour-to-hour correlation (r = 0.931) and a moderate correlation at a 2-hr lag (0.289); day-to-day (i.e., 24 hr lag) hourly observations were uncorrelated. Daily R S means were well correlated at a 1-day lag (r = 0.856) but not at any further time lag. In a linear mixed-effects model predicting R S , soil temperature and moisture exerted consistently strong effects regardless of time scale, and model coefficient of variability was generally high (>80%). These results provide new opportunities to explore the drivers and variability of R S fluxes, quantify sampling requirements, and improve error propagation.Plain Language Summary Soils give off carbon dioxide, generated by microbes and plant roots, to the atmosphere. How this "soil respiration" (R S ) varies in time, as one measures at minute, hourly, daily, or longer time scales, is related to the processes driving it and has implications for how we estimate this flow of carbon across space and time. We measured R S in a coastal deciduous forest in Maryland, USA, and found that the variability of R S -how much it changed between successive measurementsvaried at the different time scales. R S values quickly became increasingly random (i.e., uncorrelated with each other) as one measured repeatedly over time. These results help us understand the factors driving this large flow of carbon to the atmosphere and improve our ability to estimate R S at times and places not directly measured.

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“…Fluxes were calculated based on the final 100 s of the 120-s measurement period as in Valverde-Barrantes et al (2007). Previous studies in these plots indicated that there was no meaningful diel variation in soil respiration (Raich 2017). Nevertheless, the order of measurements was changed at every sample time.…”

Section: Soilmentioning

confidence: 99%

Tropical tree species traits drive soil cation dynamics via effects on pH: a proposed conceptual framework

Russell

Hall

Raich

2017

Ecological Monographs

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Humid tropical forests are major players in the global carbon cycle, despite evidence that cations (rock‐derived, positively charged ions) can limit or co‐limit net primary productivity (NPP). In mature forests, tight cation cycling, i.e., without leaching losses, could maintain cation stocks on site. That mechanism does not explain how regenerating tropical secondary forest trees start from seeds and accrue large cation stocks in biomass, when growing on soils depleted in available cations. We propose a new mechanism that links tree species’ traits to soil cation availability via impacts on soil pH, a master biogeochemical driver. We tested plot‐level effects of tree species on soil pH, soil extractable cations, and cation accrual in biomass in a unique, 25‐yr‐old, randomized‐complete‐block experiment in which climate, soil, and previous land‐use history were similar across four native tree species grown in mono‐dominant plantations in Costa Rica. Surface‐soil pH in this Oxisol, initially 4.52 ± 0.02 (mean ± SE (standard error)), declined to 4.14 ± 0.02 under Pentaclethra macroloba, a nodulated legume, and increased to 4.71 ± 0.08 under Vochysia guatemalensis, an aluminum (Al) accumulator. The range in pH corresponds to a five‐fold difference in proton concentrations, which is sufficient to alter dispersion of organo‐mineral colloids. Cation stocks in biomass differed across species by 1.7‐, 1.9‐, 2.8‐, 2.9‐, 3.1‐, 3.5‐, and 17.2‐fold for iron (Fe), calcium (Ca), potassium (K), manganese (Mn), strontium (Sr), magnesium (Mg), and Al, respectively. Differential acquisition of available soil cations was an unlikely explanation for measured differences among species because changes in extractable soil cation stocks were unrelated to cation accrual in biomass. Soil pH and biomass cation stocks were highly correlated, however. By our proposed conceptual framework, species traits that strongly increase proton concentrations and decrease pH in soil, e.g., support of N fixation, increase colloid aggregation, reducing cation availability. Traits that reduce soil protons and increase pH, e.g., Al+3 accumulation, disperse colloids, thereby releasing cations occluded during pedogenesis. This highlights a novel biogeochemical role for the Al‐accumulation trait, i.e., liberation of occluded soil cations. Further studies would clarify effects of soil pH on cation supply via colloid dispersion, and its importance for nutrient acquisition in cation‐depleted soils.

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Temporal Variability of Soil Respiration in Experimental Tree Plantations in Lowland Costa Rica

Cited by 20 publications

References 76 publications

Significant Diel Variation of Soil Respiration Suggests Aboveground and Belowground Controls in a Tropical Moist Forest in Puerto Rico

Significant Diel Variation of Soil Respiration Suggests Aboveground and Belowground Controls in a Tropical Moist Forest in Puerto Rico

Soil Respiration Variability and Correlation Across a Wide Range of Temporal Scales

Tropical tree species traits drive soil cation dynamics via effects on pH: a proposed conceptual framework

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