scholarly journals Controls on Soil Organic Carbon Partitioning and Stabilization in the California Sierra Nevada

Soil Systems ◽  
2018 ◽  
Vol 2 (3) ◽  
pp. 41 ◽  
Author(s):  
Craig Rasmussen ◽  
Heather Throckmorton ◽  
Garrett Liles ◽  
Katherine Heckman ◽  
Stephen Meding ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Sierra Nevada ◽  
Residence Time ◽  
Ponderosa Pine ◽  
Forest Ecosystems ◽  
Storage Capacity ◽  
Parent Materials ◽  
Soil Weathering ◽  
White Fir

There is a critical need to quantify the role of soil mineral composition on organic carbon (C) stabilization in forest soils. Here, we address this need by studying a matrix of forest ecosystems and soil parent materials with the objective of quantifying controls on the physical partitioning and residence time of soil organic carbon. We sampled soil profiles across a climate gradient on the western slope of the California Sierra Nevada, focusing on three distinct forest ecosystems dominated by ponderosa pine, white fir, or red fir, on three igneous parent materials that included granite, andesite, and basalt. Results indicated that short-range order mineral phases were the dominant factors accounting for the variation in soil carbon content and residence time. The results further suggested an interaction between ecosystem fire regime and the degree of soil weathering on the partitioning, chemical composition, and residence time of C in density separated soil physical fractions. These results suggest a link between the degree of soil weathering and C storage capacity, with a greater divergence in storage capacity and residence time in the Inceptisols, Entisols, and Andisols of the white fir and red fir ecosystems relative to minimal variation in the highly weathered Ultisols and Alfisols of the ponderosa pine ecosystem.

scholarly journals Observations of HNO<sub>3</sub>, ΣAN, ΣPN and NO<sub>2</sub> fluxes: evidence for rapid HO<sub>x</sub> chemistry within a pine forest canopy

2007 ◽  
Vol 7 (3) ◽  
pp. 7087-7136 ◽  
Author(s):  
D. K. Farmer ◽  
R. C. Cohen
Keyword(s):  
Nitrogen Oxides ◽  
Sierra Nevada ◽  
Residence Time ◽  
Ponderosa Pine ◽  
Forest Canopy ◽  
Similarity Theory ◽  
Peroxy Radical ◽  
Pine Forest ◽  
Alkyl Nitrates ◽  
Emission Fluxes

Abstract. Measurements of exchange of reactive nitrogen oxides between the atmosphere and a ponderosa pine forest in the Sierra Nevada Mountains are reported. During winter, we observe upward fluxes of NO2, and downward fluxes of total peroxy and peroxy acyl nitrates (ΣPNs), total gas and particle phase alkyl and multifunctional alkyl nitrates (ΣANs(g+p), and the sum of gaseous HNO3 and semi-volatile NO3− particles (HNO3(g+p). We use calculations of the vertical profile and flux of NO, partially constrained by observations, to show that net midday ΣNOyi fluxes in winter are –4.9 ppt m s−1. The signs and magnitudes of these wintertime individual and ΣNOyi fluxes are in the range of prior measurements. In contrast, during summer, we observe downward fluxes only of ΣANs(g+p), and upward fluxes of HNO3(g+p), ΣPNs and NO2 with signs and magnitudes that are unlike most, if not all, previous observations and analyses of fluxes of individual nitrogen oxides. The results imply that the mechanisms contributing to NOy fluxes, at least at this site, are much more complex than previously recognized. We show that the observations of upward fluxes of HNO3(g+p) and ΣPNs during summer are consistent with oxidation of NO2 and acetaldehyde by OH with the product of concentration and residence time equal to 1.1×1010 molec OH cm−3 s, e.g. 3×107 molecules cm−3 OH for a 400 s canopy residence time. We show that ΣAN(g+p) fluxes are consistent with this same OH if the reaction of OH with ΣANs produces either HNO3 or NO2 in 6–30% yield. Calculations of NO fluxes constrained by the NO2 observations and the inferred OH indicate that NOx fluxes are downward into the canopy because of the substantial conversion of NOx to HNO3 and ΣPNs in the canopy. Even so, we derive that NOx emission fluxes of ~15 ng(N) m−2 s−1 at midday during summer are required to balance the NOx and NOy flux budgets. These fluxes are partly explained by estimates of soil emissions (estimated to be between 3 and 6 ng(N) m−2 s−1). One possibility for the remainder of the NOx source is large HONO emissions. Alternatively, the 15 ng(N) m−2 s−1 emission estimate may be too large, and the budget balanced if the deposition of HNO3 and ΣPNs is slower than we estimate, if there are large errors in either our understanding of peroxy radical chemistry, or our assumptions that the budget is required to balance because the fluxes do not obey similarity theory.

scholarly journals Altitudinal variation of soil organic carbon stock in tropical forest of Courtallam hills, Southern Western Ghats of India

2020 ◽  
Vol 7 (3) ◽  
pp. 702-714
Author(s):  
E. Pandian ◽  
◽  
P. Ravichandran ◽  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Tropical Forest ◽  
Western Ghats ◽  
Carbon Stock ◽  
Forest Ecosystems ◽  
Soil Organic Carbon Stock ◽  
Southern Western Ghats ◽  
Organic Carbon Stock ◽  
Soc Stocks

The climate change and carbon mitigation through forest ecosystems play an important role in the global perspective. Soil is a huge carbon reservoir and its storage capacity varied greatly with forest type and altitude. The mountain ecosystem varies in soil organic carbon stock (SOC) due to variations in soil types, climatic conditions, vegetation patterns and elevational gradients. Soil organic carbon stockswere measured at three depths (0–10, 10–20, and 20–30 cm) in five different forest elevation (200, 400, 600, 800, and 1000 m asl) on Courtallam hills, Southern Western Ghats, India. SOC stocks increased significantly with the increase in altitude (P<0.05) at all the three layers (0–10, 10–20 and 20–30 cm). A total of SOC stocks ranged from 42.79 mg ha-1at 0–30 cm depth were observed in lower altitude (200 m) and the highest value of 50.25 mg ha-1 at 0–30 cm depth was observed in mid-elevation 600 m, while in other elevational showed 46.45, 48.49 and 45.05 mg ha-1 in 400, 800 and 1000 m respectively. SOC ranged from 17.89 to 22.37 mg ha-1 in soil surface layer (0–10 cm), 14.00 to 16.573 mg ha-1 in middle layer (10–20 cm) and 9.08 to 11.35 mg ha-1 in the bottom layer (20–30 cm). These results would also enhance our ability to assesses the role of these forest types in soil carbon sequestration and for developing and validating the SOC models for tropical forest ecosystems.

scholarly journals Predicting Soil Organic Carbon and Soil Nitrogen Stocks in Topsoil of Forest Ecosystems in Northeastern China Using Remote Sensing Data

2020 ◽  
Vol 12 (7) ◽  
pp. 1115 ◽  
Author(s):  
Shuai Wang ◽  
Qianlai Zhuang ◽  
Xinxin Jin ◽  
Zijiao Yang ◽  
Hongbin Liu
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Quality ◽  
Vegetation Index ◽  
Forest Ecosystems ◽  
Remotely Sensed ◽  
Northeastern China ◽  
Boosted Regression Trees ◽  
Land Policy ◽  
The Government

Forest ecosystems play an important role in regional carbon and nitrogen cycling. Accurate and effective monitoring of their soil organic carbon (SOC) and soil total nitrogen (STN) stocks provides important information for soil quality assessment, sustainable forestry management and climate change policy making. In this study, a geographical weighted regression (GWR) model, a multiple stepwise regression (MLSR) model, and a boosted regression trees (BRT) model were compared to obtain the best prediction of SOC and STN stocks of the forest ecosystems in northeastern China. Five-hundred and thirteen topsoil (0–30 cm) samples (10.32 kg m−2 (±0.53) for SOC, 1.21 kg m−2 (±0.32) for STN), and 9 remotely-sensed environmental variables were collected and used for the model development and verification. By comparing with independent verification data, the best model (BRT) achieved R2 = 0.56 and root mean square error (RMSE) = 00.85 kg m−2 for SOC stocks, R2 = 0.51 and RMSE = 0.22 kg m−2 for STN stocks. Of all the remotely-sensed environment variables, soil adjusted vegetation index (SAVI) and normalized difference vegetation index (NDVI) are of the highest relative importance in predicting SOC and STN stocks. The spatial distribution of the predicted SOC and STN stocks gradually decreased from northeast to southwest. This study provides an attempt to rapidly predict SOC and STN stocks in the dense vegetation covered area. The results can help evaluate soil quality and facilitate land policy and regulation making by the government in the region.

Soil organic carbon dynamics and sequestration potential in cropland-grassland agro-ecosystems

2021 ◽  
Author(s):  
Thomas Guillaume ◽  
David Makowski ◽  
Zamir Libohova ◽  
Luca Bragazza ◽  
Sokrat Sinaj
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Management Practices ◽  
Storage Capacity ◽  
Agricultural Soils ◽  
C Sequestration ◽  
Boundary Line ◽  
Monitoring Networks ◽  
Soil C ◽  
Sequestration Potential

&lt;p&gt;Increasing soil organic carbon (SOC) in agro-ecosystems enables to address simultaneously food security as well as climate change adaptation and mitigation. Croplands represent a great potential to sequester atmospheric C because they are depleted in SOC. Hence, reliable estimations of SOC deficits in agro-ecosystems are crucial to evaluate the C sequestration potential of agricultural soils and support management practices. Using a 30-year old soil monitoring networks with 250 sites established in western Switzerland, we identified factors driving the long-term SOC dynamics in croplands (CR) and permanent grasslands (PG) and quantified SOC deficit. A new relationship between the silt + clay (SC) soil particles and the C stored in the mineral-associated fraction (MAOMC) was established. We also tested the assumption about whether or not PG can be used as carbon-saturated reference sites. The C-deficit in CR constituted about a third of their potential SOC content and was mainly affected by the proportion of temporary grassland in the crop rotation. SOC accrual or loss were the highest in sites that experienced land-use change. The MAOMC level in PG depended on the C accrual history, indicating that C-saturation level was not coincidental. Accordingly, the relationship between MAOMC and SC to determine soil C-saturation should be estimated by boundary line analysis instead of least squares regressions. In conclusion, PG do provide an additional SOC storage capacity under optimal management, though the storage capacity is greater for CR.&lt;/p&gt;

Effects of forest fire disturbance on soil organic carbon in forest ecosystems: A review

2020 ◽  
Vol 40 (6) ◽  
Author(s):  
胡海清，罗斯生，罗碧珍，魏书精，吴泽鹏，王振师，李小川，周宇飞 HU Haiqing
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Forest Fire ◽  
Forest Ecosystems ◽  
Fire Disturbance
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