Application of structural equation modeling for assessing relationships between organic carbon and soil properties in semiarid Mediterranean region

Brahim, Nadhem; Breton, Didier; Gallali, Tahar; Bernoux, Martial

doi:10.1007/bf03326218

Cited by 42 publications

(30 citation statements)

References 74 publications

(70 reference statements)

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“…The range of its goodness‐of‐fit index values (Table S1) corroborated the good fit of the data (Brahim et al. ). Thus, Soil had a significant and positive direct effect on Fire and on Flora (Fig.…”

Section: Resultssupporting

confidence: 77%

Relationships between fire history, edaphic factors and woody vegetation structure and composition in a semi‐arid savanna landscape (Niger, West Africa)

Diouf

Barbier

Lykke

et al. 2012

Applied Vegetation Science

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Question What are the relationships between edaphic factors, fire regime and woody vegetation structure and composition in savannas at landscape to regional scales? Location The Transboundary ‘W’ Regional Park, Niger, West Africa. Methods We focused on a protected savanna ecosystem with rainfall of 700 mm yr−1, where rainfall is not expected to be a strong limiting factor for tree cover, and with historically low grazer and browser densities. A burned area history map was created over 7 yr using the high temporal resolution Aqua MODIS space‐borne sensor. In the field, the composition and structural parameters of the woody layer, as well as soil samples, were acquired in 137 plots of 0.09 ha each, based on a stratified random sampling approach to sampling the fire regime (seasonality and frequency). Using classical multivariate methods, we analysed the correlations between woody cover characteristics, fire regime and soil and geomorphological factors. Results In spite of management practices aimed at generalizing early fire every year, the fire regime created a diverse spatial structure, with some vegetation less prone to burning (fire‐free) and other types that burned very frequently. These diverse fire histories showed correlations with gradients of both structure and composition of the woody layer. Soil variables had a higher explanatory power for vegetation structure and composition than fire. Conclusions Among the plausible causal chains between fire regime, soil factors and woody vegetation structure and composition, our results showed better agreement with a model in which fire regime is more a consequence than a cause of the other factors. This contrasts with bottleneck/perturbation theories as well as management practices, but meets the common sense opinions of field practitioners. Although our regional approach should be complemented by controlled experiments at a local scale, it does appear that investments in annual efforts to organize early fire campaigns in many protected areas may need to be reassessed.

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Section: Resultssupporting

confidence: 77%

Relationships between fire history, edaphic factors and woody vegetation structure and composition in a semi‐arid savanna landscape (Niger, West Africa)

Diouf

Barbier

Lykke

et al. 2012

Applied Vegetation Science

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“…Organic matter (OM) has an essential role in improving physical, chemical, and biological properties of soils, and it is considered as one of the most important indicators in evaluating soil quality and health (Brahim et al 2011;Vaughan et al 2011;Ghosh et al 2012). The addition of organic amendments in rice agro-ecosystems (paddy soils) can be responsible for large accumulations in soil organic carbon and enhancements in crop productivity.…”

Section: Introductionmentioning

confidence: 99%

Changes of CO2 emission and labile organic carbon as influenced by rice straw and different water regimes

Ibrahim

Cao

Zhan

et al. 2013

Int. J. Environ. Sci. Technol.

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Crop residues under different water regimes can cause significant alterations in soil organic carbon fractions, and in turn, soil-atmospheric carbon dioxide (CO 2 ) emissions. To evaluate the effect of rice straw application on CO 2 emissions and labile organic carbon fractions under different water regimes, an incubation experiment was conducted for 90 days. Ten treatments were developed from the interaction between five water levels (100, 85, 70, 55, and 40 % of water-holding capacity (WHC)) with and without incorporation of rice straw. Peaks of CO 2 fluxes were observed after 13 days of rice straw incorporation, which decreased gradually till the end of the incubation period. The incorporation of rice straw caused significant increases in CO 2 fluxes by 2.77-2.83 times from the paddy soil. In the presence of rice straw, the highest CO 2 fluxes were generally observed at W3 (70 % of WHC), whereas the lowest fluxes were occurred at W1 (100 % of WHC). Addition of rice straw under a range of water regimes markedly improved the transformation of soil organic carbon and labile organic carbon pools such as dissolved organic carbon, microbial biomass carbon, light fraction organic carbon, particulate organic carbon, and permanganate oxidizable carbon. The significant correlations between all labile soil organic carbon fractions and CO 2 concentrations confirmed their important roles in the emission of CO 2 from the paddy soil. In summary, the results suggest that light fraction organic carbon, particulate organic carbon, and permanganate oxidizable carbon were more sensitive indicators for CO 2 emissions and organic matter alterations as compared to other carbon fractions.

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“…Application studies in forests [12,14,42,43], shrublands [13], wetlands [35], and other ecosystems [15] have proved the scientific basis and reliability of the model. Its importance is that it allows for the detection of topographic, stand structural, and soil characteristic factors that are responsible for structural and functional changes.…”

Section: Discussionmentioning

confidence: 99%

Relationship between Soil Characteristics and Stand Structure of Robinia pseudoacacia L. and Pinus tabulaeformis Carr. Mixed Plantations in the Caijiachuan Watershed: An Application of Structural Equation Modeling

Wei

Liang

et al. 2018

Forests

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Abstract:In order to study the multi-factor coupling relationships between typical Robinia pseudoacacia L. and Pinus tabulaeformis Carr. mixed plantations in the Caijiachuan basin of the Loess Plateau of Shanxi Province, West China, 136 sample plots were selected for building a structural equation model (SEM) of three potential variables: terrain, stand structure, and soil characteristics. Additionally, the indicators (also known as observed variables) were studied in this paper, including slope, altitude, diameter at breast height (DBH), tree height (TH), tree crown area, canopy density, stand density, leaf area index (LAI), soil moisture content, soil maximum water holding capacity (WHC), soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), ammonia-nitrogen (NH 3 -N), nitrate-nitrogen (NO 3 -N), and available phosphorus (AP). The results showed that terrain was the most important factor influencing soil moisture and nutrients, with a total impact coefficient of 1.303 and a direct path coefficient of 0.03, which represented mainly positive impacts; while correspondingly stand structure had a smaller negative impact on soil characteristics, with a total impact coefficient of −0.585 and a direct path coefficient of −0.01. The terrain also had a positive impact on the stand structure, with a total impact coefficient of 0.487 and a direct path coefficient of 0.63, indicating that the topography factors were more suitable for site conditions and both the stand structure and the soil moisture and nutrient conditions were relatively superior. By affecting the stand structure, terrain could restrict some soil, water, and nutrient functions of soil and water conservation. The influence coefficients of the four observed variables of DBH, stand density, soil water content, and organic matter, and potential variable topography reached 0.686, −0.119, 1.117, and 0.732, respectively; and the influence coefficients of soil moisture, organic matter and stand structure were −0.502 and −0.329, respectively. Therefore, besides observing the corresponding latent variables, the observed variables had a considerable indirect influence on other related latent variables. These relationships showed that the measures, such as changing micro-topography and adjusting stand density, should effectively maintain or enhance soil moisture and nutrient content so as to achieve improved soil and water conservation benefits in the ecologically important Loess Area.

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Application of structural equation modeling for assessing relationships between organic carbon and soil properties in semiarid Mediterranean region

Cited by 42 publications

References 74 publications

Relationships between fire history, edaphic factors and woody vegetation structure and composition in a semi‐arid savanna landscape (Niger, West Africa)

Relationships between fire history, edaphic factors and woody vegetation structure and composition in a semi‐arid savanna landscape (Niger, West Africa)

Changes of CO2 emission and labile organic carbon as influenced by rice straw and different water regimes

Relationship between Soil Characteristics and Stand Structure of Robinia pseudoacacia L. and Pinus tabulaeformis Carr. Mixed Plantations in the Caijiachuan Watershed: An Application of Structural Equation Modeling

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