Deep in the Sierra Nevada critical zone: Saprock represents a large terrestrial organic carbon stock

Abstract Large uncertainty remains in the spatial distribution of deep soil organic carbon (OC) storage and how climate controls belowground OC. This research aims to quantify OC stocks, characterize soil OC age and chemical composition, and evaluate climatic impacts on OC storage from the soil surface through the deep critical zone to bedrock. These objectives were carried out at four sites along a bio-climosequence in the Sierra Nevada, California. On average, 74% of OC was stored below the A horizon, and up to 30% of OC was stored in saprock (friable weakly weathered bedrock). Radiocarbon, spectroscopic, and isotopic analyses revealed the coexistence of very old organic matter (OM) (mean radiocarbon age = 20,300 y BP) with relatively recent OM (mean radiocarbon age = 4,800 y BP) and highly decomposed organic compounds with relatively less decomposed material in deep soil and saprock. This co-mingling of OM suggests OC is prone to both active cycling and long-term protection from degradation. In addition to having direct effects on OC cycling, climate indirectly controls deep OC storage through its impact on the degree of regolith weathering (e.g. thickening). Although deep OC concentrations are low relative to soil, thick saprock represents a large, previously unrealized OC pool.

Download Full-text

Soil organic carbon dynamics and controlling factors in typical ecosystems of the Qinghai-Tibet Platea critical zone

10.5194/egusphere-egu2020-20806 ◽

2020 ◽

Author(s):

Hongyun Yao ◽

Pei Wang ◽

Chao Yang ◽

Xuebao Xu ◽

Junqi Wei ◽

...

Keyword(s):

Organic Carbon ◽

Environmental Changes ◽

Stable Carbon Isotope ◽

Soil Surface ◽

Carbon Dynamics ◽

Critical Zone ◽

Controlling Factors ◽

Desert Ecosystem ◽

Tibet Plateau ◽

Critical Zones

The interface of the Earth&#8217;s critical zone is the place where organic carbon is dramatically decomposed and transformed&#65294;The dynamics and fate of organic carbon serve as an important foundation to reveal the material transportation in the Qinghai-Tibet Platea critical zones. This research analyzed temperature, soil moisture and stable carbon isotope values (&#948;13C) of CO2 in different soil layers, measure soil surface respiration using soil respiration measurement system (LI-8100) , and analyzed carbon storage , carbon dynamics and its controlling factors in critical zones in seven typical ecosystems of the Qinghai-Tibet Platea. The results found that the underground carbon content and its controlling factors were very different in different ecosystems on the Qinghai-Tibet Plateau. The main controlling factor of carbon changes was water in alpine steppe and desert ecosystem while it was temperature in alpine meadow. In the meanwhile, this research also measured the maximum carboxylation rate (Vcmax) of dominant plants in each ecosystem, trying to explore the different carbon inputs in different ecosystems. Understanding the impacts of environmental changes on the geochemical cycling of critical zone&#8217;s organic carbon in the Qinghai-Tibet Platea would benefit the optimization of carbon cycling model and climate change predictions&#65294;

Download Full-text

Effects of Soil Compaction on Height Growth of a California Ponderosa Pine Plantation

Western Journal of Applied Forestry ◽

10.1093/wjaf/1.4.104 ◽

1986 ◽

Vol 1 (4) ◽

pp. 104-108 ◽

Cited By ~ 4

Author(s):

J. A. Helms ◽

C. Hipkin ◽

E. B. Alexander

Keyword(s):

Organic Carbon ◽

Bulk Density ◽

Sierra Nevada ◽

Pinus Ponderosa ◽

Ponderosa Pine ◽

Soil Compaction ◽

Soil Surface ◽

Surface Characteristics ◽

Soil Bulk Density ◽

Height Growth

Abstract An analysis was made of the extent to which observed variability in plantation height growth could be explained by variability in soil surface characteristics that are modified by harvesting and site preparation activities. The study was done in a 16-year-old ponderosa pine (Pinus ponderosa) plantation in the Sierra Nevada of California. Annual height growth of all 423 trees within a 0.48 ha area was measured together with soil bulk density, A-Horizon thickness, and shrub competition. Soil organic carbon and mineralizeable nitrogen were measured on a subsample of 72 trees. Trees in areas of highest bulk density grew 43% less at age 1 and 13% less at age 15 than those in areas of lowest bulk density. Annual shoot growth was markedly reduced for 4 consecutive years following 2 years of below-normal precipitation, especially in trees growing in soils of lowest bulk density. Bulk density, A-Horizon thickness, and shrub cover accounted for only 13 to 23% of variability in height growth of the 423-tree sample. These same variables, plus organic carbon and mineralizeable nitrogen, accounted for 31% of variability in height growth of the 72-tree sample. West. J. Appl. For. 1:104-108, Oct. 1986.

Download Full-text

Land‐use conversion changes deep soil organic carbon stock in the Chinese Loess Plateau

Land Degradation and Development ◽

10.1002/ldr.3644 ◽

2020 ◽

Vol 32 (1) ◽

pp. 505-517

Author(s):

Bin‐Bin Li ◽

Pan‐Pan Li ◽

Xiao‐Mei Yang ◽

Hai‐Bing Xiao ◽

Ming‐Xiang Xu ◽

...

Keyword(s):

Land Use ◽

Organic Carbon ◽

Carbon Stock ◽

Chinese Loess Plateau ◽

Deep Soil ◽

Soil Organic Carbon Stock ◽

Land Use Conversion ◽

Chinese Loess ◽

Organic Carbon Stock ◽

The Chinese Loess Plateau

Download Full-text

Faculty Opinions recommendation of Stability of organic carbon in deep soil layers controlled by fresh carbon supply.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1102345.558386 ◽

2008 ◽

Author(s):

Christian Körner

Keyword(s):

Organic Carbon ◽

Deep Soil ◽

Soil Layers ◽

Carbon Supply

Download Full-text

Grazing exclosures increase soil organic carbon stock at a rate greater than “4 per 1000” per year across agricultural landscapes in Northern Ethiopia

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.146821 ◽

2021 ◽

Vol 782 ◽

pp. 146821

Author(s):

Florent Noulèkoun ◽

Emiru Birhane ◽

Habtemariam Kassa ◽

Alemayehu Berhe ◽

Zefere Mulaw Gebremichael ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Stock ◽

Agricultural Landscapes ◽

Northern Ethiopia ◽

Soil Organic Carbon Stock ◽

Organic Carbon Stock

Download Full-text

Estimating soil organic carbon stock change at multiple scales using machine learning and multivariate geostatistics

Geoderma ◽

10.1016/j.geoderma.2021.115356 ◽

2021 ◽

Vol 403 ◽

pp. 115356

Author(s):

Gábor Szatmári ◽

László Pásztor ◽

Gerard B.M. Heuvelink

Keyword(s):

Machine Learning ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Stock ◽

Multiple Scales ◽

Multivariate Geostatistics ◽

Soil Organic Carbon Stock ◽

Carbon Stock Change ◽

Organic Carbon Stock ◽

Stock Change

Download Full-text

Vertical distribution of soil available phosphorus and soil available potassium in the critical zone on the Loess Plateau, China

Scientific Reports ◽

10.1038/s41598-021-82677-4 ◽

2021 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Hanyang Tian ◽

Jiangbo Qiao ◽

Yuanjun Zhu ◽

Xiaoxu Jia ◽

Ming’an Shao

Keyword(s):

Vertical Distribution ◽

Loess Plateau ◽

Clay Content ◽

Exponential Model ◽

Critical Zone ◽

Available Phosphorus ◽

Soil Core ◽

The Loess Plateau ◽

Deep Soil ◽

Soil Available Phosphorus

AbstractSoil available phosphorus (SAP) and soil available potassium (SAK) are important elements in the growth of plants. However, limited data are available regarding the vertical distribution of SAP and SAK in deep soil profiles. In this study, we investigated the vertical variations in SAP and SAK in the critical zone on the Loess Plateau (50–200 m), China, by using classical statistical and geostatistical methods. The soil samples were collected from the top of the soil profile down to the bedrock by soil core drilling at five typical sites. SAP decreased throughout the profile. Whereas the SAK exhibited an increasing trend at all sites. The mean SAP concentration ranged from 0.94 to 32.56 mg kg–1 at the sampling sites and the SAK concentration ranged from 44.51 to 229.31 mg kg–1. At all of the sampling sites, SAK was significantly positively correlated with the depth and clay content, but there was a significantly negative correlation between the SAK and the sand content. The exponential model could fit most variograms of SAP and SAK at all sampling sites. The results obtained in this study to improve our comprehension of the SAP or SAK distribution conditions on the Loess Plateau, which is important for reasonable fertilizer application and vegetation planting practices.

Download Full-text

Effects of Urban Forest Types and Traits on Soil Organic Carbon Stock in Beijing

Forests ◽

10.3390/f12040394 ◽

2021 ◽

Vol 12 (4) ◽

pp. 394

Author(s):

Xinhui Xu ◽

Zhenkai Sun ◽

Zezhou Hao ◽

Qi Bian ◽

Kaiyue Wei ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Stock ◽

Urban Forest ◽

Coniferous Forest ◽

Predictor Variable ◽

Urban Forests ◽

Least Squares Regression ◽

Forest Types ◽

Organic Carbon Stock

Forests can affect soil organic carbon (SOC) quality and distribution through forest types and traits. However, much less is known about the influence of urban forests on SOC, especially in the effects of different forest types, such as coniferous and broadleaved forests. Our objectives were to assess the effects of urban forest types on the variability of SOC content (SOC concentration (SOCC) and SOC density (SOCD)) and determine the key forest traits influencing SOC. Data from 168 urban forest plots of coniferous or broadleaved forests located in the Beijing urban area were used to predict the effects of forest types and traits on SOC in three different soil layers, 0–10 cm, 10–20 cm, and 20–30 cm. The analysis of variance and multiple comparisons were used to test the differences in SOC between forest types or layers. Partial least squares regression (PLSR) was used to explain the influence of forest traits on SOC and select the significant predictors. Our results showed that in urban forests, the SOCC and SOCD values of the coniferous forest group were both significantly higher than those of the broadleaved group. The SOCC of the surface soil was significantly higher than those of the following two deep layers. In PLSR models, 42.07% of the SOCC variance and 35.83% of the SOCD variance were explained by forest traits. Diameter at breast height was selected as the best predictor variable by comparing variable importance in projection (VIP) scores in the models. The results suggest that forest types and traits could be used as an optional approach to assess the organic carbon stock in urban forest soils. This study found substantial effects of urban forest types and traits on soil organic carbon sequestration, which provides important data support for urban forest planning and management.

Download Full-text