scholarly journals Minimising soil organic carbon erosion by wind is critical for land degradation neutrality

2019 ◽  
Vol 93 ◽  
pp. 43-52 ◽  
Author(s):  
Adrian Chappell ◽  
Nicholas P. Webb ◽  
John F. Leys ◽  
Cathleen M. Waters ◽  
Susan Orgill ◽  
...  
Author(s):  
Dusko Mukaetov Mukaetov ◽  
Ivan Blinkov ◽  
Hristina Poposka

Land degradation neutrality (LDN) is defined as a "state whereby the amount and quality of land resources nec-essary to support ecosystem functions and services and enhance food security remain stable or increase within specified temporal and spatial scales and ecosystems". The baseline is expressed as the initial (t0) estimated value of each of the three indicators, used as proxies of land-based natural capital and the ecosystem services that flow from that land base: land cover/land use change, land productivity status and trends, soil organic carbon status and trends. The baseline of LDN was calculated with estimation of the average values across the 10 years baseline period of the following indica-tors: Land Cover/Land Cover change (LC/LCC), Land Productivity Dynamics (LPD) and Soil Organic Carbon (SOC). Three tier approaches for computation of the selected indicators were used: Tier 1: Global/regional Earth observation, geospatial information and modelling; Tier 2: National statistics (only for LC/LCC) and Tier 3: Field survey. Most sig-nificant changes in LC for the period 2000/2012 are in the categories of Forest land and Shrubs/grasslands. According the global data sets used for analysis of LPD, the total affected area with depletion of Land productivity for the period 2000/2010 is identified on a only 2.35 % of the country territory. The available global data sets gives a model SOC lev-els for the period 2000/2010. According these data, the total loss of SOC in our country is estimated on 3951 t.


2015 ◽  
Vol 7 (1) ◽  
pp. 115-145 ◽  
Author(s):  
Y. Mohawesh ◽  
A. Taimeh ◽  
F. Ziadat

Abstract. Land degradation resulting from improper land use and management is a major cause of declined productivity in the arid environment. The objectives of this study were to examine the effects of a sequence of land use changes, soil conservation measures, and the time since their implementation on the degradation of selected soil properties. The climate for the selected 105 km2 watershed varies from semi-arid sub-tropical to Mediterranean sub-humid. Land use changes were detected using aerial photographs acquired in 1953, 1978, and 2008. A total of 218 samples were collected from 40 sites in three different rainfall zones to represent different land use changes and different lengths of time since the construction of stone walls. Analyses of variance were used to test the differences between the sequences of land use changes (interchangeable sequences of forest, orchards, field crops, and range), the time since the implementation of soil conservation measures, and rainfall on the thickness of the A-horizon, soil organic carbon content, and texture. Soil organic carbon reacts actively with different combinations and sequences of land use changes. The time since stone walls were constructed showed significant impacts on soil organic carbon and the thickness of the surface horizon. The effects of changing the land use and whether the changes were associated with the construction of stone walls, varied according to the annual rainfall. The results help in understanding the effects of land use changes on land degradation processes and carbon sequestration potential and in formulating sound soil conservation plans.


2011 ◽  
Vol 75 (4) ◽  
pp. 1503-1512 ◽  
Author(s):  
Charmaine N. Mchunu ◽  
Simon Lorentz ◽  
Graham Jewitt ◽  
Alan Manson ◽  
Vincent Chaplot

2020 ◽  
Author(s):  
Leigh Winowiecki ◽  
Tor-Gunnar Vågen

<p>Maintaining soil organic carbon (SOC) content is recognized as an important strategy for a well-functioning soil ecosystem. The UN Convention to Combat Desertification (UNCCD) recognizes that reduced SOC content can lead to land degradation, and ultimately low land and agricultural productivity. SOC is almost universally proposed as the most important indicator of soil health, not only because SOC positively influences multiple soil properties that affect productivity, including cation exchange capacity and water holding capacity, but also because SOC content reflects aboveground activities, including especially agricultural land management. To be useful as an indicator, it is crucial to assess the importance of both inherent soil properties as well as external factors (climate, vegetation cover, land management, etc.) on SOC dynamics across space and time. This requires large, reliable and up-to-date soil health data sets across diverse land cover classes. The Land Degradation Surveillance Framework (LDSF), a well-established method for assessing multiple biophysical indicators at georeferenced locations, was employed in nine countries across the tropics (Burkina Faso, Cameron, Honduras, India, Indonesia, Kenya, Nicaragua, Peru, and South Africa) to assess the influence of land use, tree cover and inherent soil properties on soil organic carbon dynamics. The LDSF was designed to provide a biophysical baseline at landscape level, and monitoring and evaluation framework for assessing processes of land degradation and the effectiveness of rehabilitation measures over time. Each LDSF site has 160 – 1000 m<sup>2</sup> plots that were randomly stratified among 16 - 1 km<sup>2</sup> sampling clusters. A total of 6918 soil samples were collected (3478 topsoil (0-20 cm) and 3435 subsoil (20-50 cm)) within this study. All samples were analyzed using mid-infrared spectroscopy and 10% of the samples were analyzed using traditional wet chemistry to develop calibration prediction models.  Validation results for soil properties (soil organic carbon (SOC), sand, and total nitrogen) showed good accuracy with R<sup>2</sup> values ranging between 0.88 and 0.96. Mean organic carbon content was 21.9 g kg<sup>-1</sup> in topsoil and 15.2 g kg<sup>-1</sup> in subsoil (median was 18.3 g kg<sup>-1</sup>  for topsoil and 10.8 g kg<sup>-1</sup> in subsoil). Forest and grassland had the highest and similar carbon content while bushland/shrubland had the lowest. Sand content played an important role in determining the SOC content across the land cover types. Further analysis will be conducted and shared on the role of trees, land cover and texture on the dynamics of soil organic carbon and the implications for LDN reporting, land restoration initiatives as well as sustainable land management recommendations.</p>


Solid Earth ◽  
2015 ◽  
Vol 6 (3) ◽  
pp. 857-868 ◽  
Author(s):  
Y. Mohawesh ◽  
A. Taimeh ◽  
F. Ziadat

Abstract. Land degradation resulting from improper land use and management is a major cause of declined productivity in the arid environment. The objectives of this study were to examine the effects of a sequence of land use changes, soil conservation measures, and the time since their implementation on the degradation of selected soil properties. The climate for the selected 105 km2 watershed varies from semi-arid sub-tropical to Mediterranean sub-humid. Land use changes were detected using aerial photographs acquired in 1953, 1978, and 2008. A total of 218 samples were collected from 40 sites in three different rainfall zones to represent different land use changes and variable lengths of time since the construction of stone walls. Analyses of variance were used to test the differences between the sequences of land use changes (interchangeable sequences of forest, orchards, field crops, and range), the time since the implementation of soil conservation measures, rainfall on the thickness of the A-horizon, soil organic carbon content, and texture. Soil organic carbon reacts actively with different combinations and sequences of land use changes. The time since stone walls were constructed showed significant impacts on soil organic carbon and the thickness of the surface horizon. The effects of changing the land use and whether the changes were associated with the construction of stone walls varied according to the annual rainfall. The changes in soil properties could be used as indicators of land degradation and to assess the impact of soil conservation programs. The results help in understanding the effects of land use changes on land degradation processes and carbon sequestration potential and in formulating sound soil conservation plans.


2021 ◽  
Author(s):  
Annamária Laborczi ◽  
Gábor Szatmári ◽  
János Mészáros ◽  
Sándor Koós ◽  
Béla Pirkó ◽  
...  

<p>‘Strategic objective 1’ of the United Nations Convention to Combat Desertification (UNCCD) aims to improve conditions of affected ecosystems, combat desertification/land degradation, promote sustainable land management, and contribute to land degradation neutrality. The indicator ‘Proportion of land that is degraded over total land area’ (SO1) is compiled from three sub-indicators: ‘Trends in land cover’ (SO1-1), ‘Trends in land productivity or functioning of the land’ (SO1-2), ‘Trends in carbon stocks above and below ground’ (SO1-3).</p><p>Soil organic carbon (SOC) stock can be adopted as the metric of SO1-3, until globally accepted methods for estimating the total terrestrial system carbon stocks will be elaborated. SOC can be considered as one of the most important properties of soil, which shows not just spatial but temporal variability. According to our previous results in the topic, UNCCD default data of SOC stock for Hungary is strongly recommended to be replaced with country specific estimation of SOC stock.</p><p>SOC stock maps were compiled in the framework of DOSoReMI.hu (Digital, Optimized, Soil Related Maps and Information in Hungary) initiative, predicted by proper digital soil mapping (DSM) method. Reference soil data were derived from a countrywide monitoring system. The selection of environmental covariates was based on the SCORPAN model. The elaborated SOC stock mapping methodology have two components: (1) point support modelling, where SOC stock is computed at the level of soil profile, and (2) spatial modelling (quantile regression forest), where spatial prediction and uncertainty quantification are carried out using the computed SOC stock values.</p><p>We analyzed how SOC stock changed between 1998 and 2016.  Nationwide SOC stock predictions were compiled for the years 1998, 2010, 2013, and 2016. For the intermediate years, we do not recommend to calculate SOC stock values, because we have no information on the dynamics of change in the intervening years. Based on the 1998 SOC stock prediction, we compiled a SOC stock map for 2018, using only land use conversion factors, according to the default data conversion values.</p><p>According to the elaborated scheme during the respective period, significant changes cannot be detected, only tendentious SOC stock changes appear. Based on our results, we recommend to use spatially predicted layers for all years when data are available, rather than calculating SOC stock change based on land use conversion factors.</p><p><strong>Acknowledgment:</strong> Our research was supported by the Hungarian National Research, Development and Innovation Office (NKFIH; K-131820) and by the Premium Postdoctoral Scholarship of the Hungarian Academy of Sciences (PREMIUM-2019-390) (Gábor Szatmári).</p>


2020 ◽  
Author(s):  
Tor-Gunnar Vågen ◽  
Leigh Ann Winowiecki ◽  
Aida Bargues-Tobella

<p>Earth observation (EO) has a large potential for mapping of soil functional properties such as soil organic carbon, soil pH or acidity, soil fertility parameters and soil texture. Recent advances in the application of EO data in combination with systematic field data sampling, standardized soil data reference analysis and the use of soil spectroscopy have shown these approaches to be both robust and scalable. We present a case study from Rwanda where we apply EO data in combination with field and laboratory data collected using the Land Degradation Surveillance Framework (LDSF) to map functional soil properties, soil erosion prevalence and land cover at fine spatial resolution. Digital soil maps were produced at a spatial resolution of 30m with an accuracy of 85 to 90%, while soil erosion prevalence was mapped with an accuracy of 86% using Landsat satellite imagery and machine learning models. </p><p>We also assess interactions between spatial assessments of soil organic carbon, soil erosion prevalence and land cover at a spatial resolution of 30m in order to identify land degradation hotspots and better target interventions to restore degraded land across four districts in Rwanda. We further explore the effects of soil erosion, root-depth restrictions and soil organic carbon content on saturated hydraulic conductivity in three LDSF sites in Nyagatare, Kayonza and Bugesera districts, respectively. Saturated hydraulic conductivity was modeled based on single-ring measurements of infiltration capacity using a modified Reynolds & Elrick steady-state single ring model for 48 LDSF plots per site. The results show significant spatial variation in infiltrability within sites.</p><p>The results of the study show the importance of rigorous protocols for sampling and analyses of soil properties and indicators of land health across landscapes. By simultaneously assessing soil properties, indicators of land degradation and soil infiltrability we demonstrate the utility of these approaches in understanding drivers of land degradation across multiple spatial scales for targeting of options for land restoration and monitoring of the effectiveness of these interventions over time across multiple dimensions of land health.</p>


2018 ◽  
Vol 10 (5) ◽  
pp. 1610 ◽  
Author(s):  
Ravic Nijbroek ◽  
Kristin Piikki ◽  
Mats Söderström ◽  
Bas Kempen ◽  
Katrine Turner ◽  
...  

Recent estimates show that one third of the world’s land and water resources are highly or moderately degraded. Global economic losses from land degradation (LD) are as high as USD $10.6 trillion annually. These trends catalyzed a call for avoiding future LD, reducing ongoing LD, and reversing past LD, which has culminated in the adoption of Sustainable Development Goal (SDG) Target 15.3 which aims to achieve global land degradation neutrality (LDN) by 2030. The political momentum and increased body of scientific literature have led to calls for a ‘new science of LDN’ and highlighted the practical challenges of implementing LDN. The aim of the present study was to derive LDN soil organic carbon (SOC) stock baseline maps by comparing different digital soil mapping (DSM) methods and sampling densities in a case study (Otjozondjupa, Namibia) and evaluate each approach with respect to complexity, cost, and map accuracy. The mean absolute error (MAE) leveled off after 100 samples were included in the DSM models resulting in a cost tradeoff for additional soil sample collection. If capacity is sufficient, the random forest DSM method out-performed other methods, but the improvement from using this more complex method compared to interpolating the soil sample data by ordinary kriging was minimal. The lessons learned while developing the Otjozondjupa LDN SOC baseline provide valuable insights for others who are responsible for developing LDN baselines elsewhere.


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