Live barriers and associated organic amendments mitigate land degradation and improve crop productivity in hillside agricultural systems of the Ecuadorian Andes
Caulfield, Mark ; Groot, Jeroen C.J. ; Fonte, Steven J. ; Sherwood, Stephen ; Oyarzun, Pedro ; Borja, Ross Mary ; Dumble, Sam ; Tittonell, Pablo - \ 2020
Land Degradation and Development (2020). - ISSN 1085-3278
Andean alder - Andes - canary grass - Ecuador - erosion - nutrient depletion
Land degradation caused by erosion and nutrient depletion in the Andes poses serious existential threats to small-scale farming. Although the potential of hedgerows to decrease water erosion is well recognised, their potential dual-use as a source of organic amendments to supplement farmer inputs is much less studied. The objective of this investigation was therefore to explore locally developed options for hedgerows that address these twin challenges. Experimental plots were installed to assess water erosion control by hedgerows and the effect of organic amendments harvested from the hedgerows on soil productivity, soil moisture, and soil fertility over the course of 2 years and three crop cycles (two of barley and one of rye). The experiment was conducted in two sites within the community at distinct elevations and associated biophysical contexts. At each site, four treatments were established, comparing a control treatment versus three types of hedgerows: (a) Andean alder, (b) canary grass strips, and (c) mixed canary grass and Andean alder. Results demonstrated that hedgerows and associated organic inputs comprised canary grass, and mixed canary grass and Andean alder reduced water erosion by 50–60% and increased biomass production by up to 1.1 Mg ha−1 and grain yield by up to 0.5 Mg ha−1. We conclude that although hedgerows are unlikely to produce sufficient quantities of organic resources to satisfy all nutrient input requirements, their potential to decrease erosion and supplement existing organic matter inputs indicates that they should be strongly considered as an option for improved agricultural management within this and similar resource constrained contexts.
Post-fire soil erosion mitigation at the scale of swales using forest logging residues at a reduced application rate
Prats, Sergio A. ; González-Pelayo, Óscar ; Silva, Flavio C. ; Bokhorst, Koen J. ; Baartman, Jantiene E.M. ; Keizer, Jan J. - \ 2019
Earth Surface Processes and Landforms 44 (2019)14. - ISSN 0197-9337 - p. 2837 - 2848.
effectiveness - erosion - mulch - organic matter - wildfire
Mulching with forest residues has proved to be highly effective in reducing post-fire soil losses at the plot scale. However, its effectiveness has not been quantified at the application rates that are typically used in operational post-fire land management (2–3 Mg ha-1 using straw), as well as at scales larger than 100 m2. The present study compared post-fire erosion rates for six convergent hillslopes or swales of 500 to 800 m2, three of which were left untreated while the other three were mulched immediately after the fire with shredded eucalypt bark at a rate of 2.4 Mg ha-1. Erosion rates were monitored at irregular intervals during the first three post-fire years, whilst ground cover was assessed yearly. Selected topsoil properties (0–2 cm) such as organic matter content and aggregate stability were determined at a single occasion – two years after the wildfire, for three micro-environments separately: bare soil, and under mulch/litter and vegetation. Soil losses on the untreated swales decreased with post-fire year from 2.2 to 0.4 and 0.11 Mg ha-1 yr-1 (respectively for the first, second and third post-fire years), while the mulched swales produced 84%, 77% and 38% less soil losses than the untreated swales. Soil losses also depended on slope aspect, with the north-facing swales producing less erosion than the west-facing ones. This could be linked to their significant differences in bare soil, vegetation and stone cover, or a combination thereof. The type of micro-environment also played a significant role in topsoil properties (stone content, bulk density, resistance to penetration/shear stress, porosity and organic matter content). The present results add to the increasing evidence that forest residues should be duly considered for operational post-fire land management. Forest residues were highly effective in reducing erosion from swales at application rates as low as the typical 2 Mg ha-1 of post-fire straw mulch.
Bioturbation and erosion rates along the soil-hillslope conveyor belt, part 1: Insights from single-grain feldspar luminescence
Román-Sánchez, Andrea ; Reimann, Tony ; Wallinga, Jakob ; Vanwalleghem, Tom - \ 2019
Earth Surface Processes and Landforms 44 (2019)10. - ISSN 0197-9337 - p. 2051 - 2065.
bioturbation - Critical Zone - erosion - feldspar luminescence - soil formation
The interplay of bioturbation, soil production and long-term erosion–deposition in soil and landscape co-evolution is poorly understood. Single-grain post-infrared infrared stimulated luminescence (post-IR IRSL) measurements on sand-sized grains of feldspar from the soil matrix can provide direct information on all three processes. To explore the potential of this novel method, we propose a conceptual model of how post-IR IRSL-derived burial age and fraction of surface-visiting grains change with soil depth and along a hillslope catena. We then tested this conceptual model by comparison with post-IR IRSL results for 15 samples taken at different depths within four soil profiles along a hillslope catena in the Santa Clotilde Critical Zone Observatory (southern Spain). In our work, we observed clear differences in apparent post-IR IRSL burial age distributions with depth along the catena, with younger ages and more linear age–depth structure for the hill-base profile, indicating the influence of lateral deposition processes. We noted shallower soils and truncated burial age–depth functions for the two erosional mid-slope profiles, and an exponential decline of burial age with depth for the hill-top profile. We suggest that the downslope increase in the fraction of surface-visiting grains at intermediate depths (20 cm) indicates creep to be the dominant erosion process. Our study demonstrates that single-grain feldspar luminescence signature-depth profiles provide a new way of tracing vertical and lateral soil mixing and transport processes. In addition, we propose a new objective luminescence-based criterion for mapping the soil-bedrock boundary, thus producing soil depths in better agreement with geomorphological process considerations. Our work highlights the possibilities of feldspar single grain techniques to provide quantitative insights into soil production, bioturbation and erosion–deposition.
Bioturbation and erosion rates along the soil-hillslope conveyor belt, part 2: Quantification using an analytical solution of the diffusion–advection equation
Román-Sánchez, Andrea ; Laguna, Ana ; Reimann, Tony ; Giráldez, Juan Vicente ; Peña, Adolfo ; Vanwalleghem, Tom - \ 2019
Earth Surface Processes and Landforms 44 (2019)10. - ISSN 0197-9337 - p. 2066 - 2080.
bioturbation - critical zone - deposition - diffusivity - erosion - feldspar luminescence dating - sensitivity and uncertainty - soil formation
Particles on soil-mantled hillslopes are subject to downslope transport by erosion processes and vertical mixing by bioturbation. Both are key processes for understanding landscape evolution and soil formation, and affect the functioning of the critical zone. We show here how the depth–age information, derived from feldspar-based single grain post-infrared infrared stimulated luminescence (pIRIR), can be used to simultaneously quantify erosion and bioturbation processes along a hillslope. In this study, we propose, for the first time, an analytical solution for the diffusion–advection equation to calculate the diffusivity constant and erosion–deposition rates. We have fitted this model to age–depth data derived from 15 soil samples from four soil profiles along a catena located under natural grassland in the Santa Clotilde Critical Zone Observatory, in the south of Spain. A global sensitivity analysis was used to assess the relative importance of each model parameter in the output. Finally, the posterior probability density functions were calculated to evaluate the uncertainty in the model parameter estimates. The results show that the diffusivity constant at the surface varies from 11.4 to 81.9 mm2 a-1 for the hilltop and hill-base profile, respectively, and between 7.4 and 64.8 mm2 a-1 at 50 cm depth. The uncertainty in the estimation of the erosion–deposition rates was found to be too high to make a reliable estimate, probably because erosion–deposition processes are much slower than bioturbation processes in this environment. This is confirmed by a global sensitivity analysis that shows how the most important parameters controlling the age–depth structure in this environment are the diffusivity constant and regolith depth. Finally, we have found a good agreement between the soil reworking rates proposed by earlier studies, considering only particle age and depth, and the estimated diffusivity constants. The soil reworking rates are effective rates, corrected for the proportion of particles actually participating in the process.
Data from: A 7000-year history of changing plant trait composition in an Amazonian landscape; the role of humans and climate
Sande, M.T. van der; Gosling, W. ; Correa-Metrio, A. ; Prado-Junior, J. ; Poorter, L. ; Oliveira, R.S. ; Mazzei, L. ; Bush, M. - \ 2019
Wageningen University & Research
Amazon - charcoal - climate change - erosion - fire - fossil pollen - functional traits - human disturbance - Peru - tropical forest
Tropical forests are shifting in species and trait composition, but the main underlying causes remain unclear because of the short temporal scales of most studies. Here, we develop a novel approach by linking functional trait data with 7000 years of forest dynamics from a fossil pollen record of Lake Sauce in the Peruvian Amazon. We evaluate how climate and human disturbances affect community trait composition. We found weak relationships between environmental conditions and traits at the taxon level, but strong effects for community-mean traits. Overall, community-mean traits were more responsive to human disturbances than to climate change; human-induced erosion increased the dominance of dense-wooded, non-zoochorous species with compound leaves, and human-induced fire increased the dominance of tall, zoochorous taxa with large seeds and simple leaves. This information can help to enhance our understanding of forest responses to past environmental changes, and improve predictions of future changes in tropical forest composition.
Trait-based approaches for guiding the restoration of degraded agricultural landscapes in East Africa
Lohbeck, Madelon ; Winowiecki, Leigh ; Aynekulu, Ermias ; Okia, Clement ; Vågen, Tor Gunnar - \ 2018
Journal of Applied Ecology 55 (2018)1. - ISSN 0021-8901 - p. 59 - 68.
agricultural land - agroecology - agroforestry - erosion - functional diversity - functional traits - land degradation - soil health - soil organic carbon - vegetation
Functional ecology provides a framework that can link vegetation characteristics of various land uses with ecosystem function. However, this application has been mostly limited to [semi-]natural systems and small spatial scales. Here, we apply functional ecology to five agricultural landscapes in Kenya, Uganda and Ethiopia, and ask to what extent vegetation characteristics contribute to soil functions that are key to farmers’ livelihoods. We used the Land Degradation Surveillance Framework (LDSF), a multi-scale assessment of land health. Each LDSF site is a 10 × 10 km landscape in which vegetation cover and erosion prevalence were measured, a tree inventory was carried out, and topsoil (0–20 cm) samples were collected for organic carbon (SOC) analysis in approximately 160 × 1,000 m2 plots. Land degradation is a recurring phenomenon across the five landscapes, indicated by high erosion prevalence (67%–99% of the plots were severely eroded). We used mixed models to assess if vegetation cover, above-ground woody biomass and the functional properties of woody vegetation (weighted-mean trait values, functional diversity [FD]) explain variation in SOC and erosion prevalence. We found that the vegetation cover and above-ground biomass had strong positive effects on soil health by increasing SOC and reducing soil erosion. After controlling for cover and biomass, we found additional marginal effects of functional properties where FD was positively associated with SOC and the abundance of invasive species was associated with higher soil erosion. Synthesis and applications. This work illustrates how functional ecology can provide much-needed evidence for designing strategies to restore degraded agricultural land and the ecosystem services on which farmers depend. We show that to ensure soil health, it is vital to avoid exposed soil, maintain or promote tree cover, while ensuring functional diversity of tree species, and to eradicate invasive species.
Winter hydrology and soil erosion processes in an agricultural catchment in Norway
Starkloff, Torsten - \ 2017
Wageningen University. Promotor(en): C.J. Ritsema, co-promotor(en): J. Stolte; R. Hessel. - Wageningen : Wageningen University - ISBN 9789463432207 - 154
catchment hydrology - erosion - winter - snow - norway - hydrologie van stroomgebieden - erosie - winter - sneeuw - noorwegen
In regions with a Nordic climate, soil erosion rates in winter and early spring can exceed those occurring during other seasons of the year. In this context, this study was initiated to improve our understanding of the interaction between agricultural soils and occurring winter conditions. The main objective was to better understand how hydrological processes in a catchment are influenced by snow, ice, and freeze-thaw cycles of soils, leading to runoff and soil erosion in winter and spring conditions.
For this purpose, detailed spatially and temporally distributed measurements and observations in a small catchment in Norway were executed during three consecutive winter/spring periods. During the winter/spring periods of 2013-2014, 2014-2015 and 2015-2016, soil water content, soil temperature, and snow cover properties were measured. In addition, numerous soil samples were taken to determine the soil hydraulic characteristics of the investigated soils and to quantify the changes in their macropore networks due to freeze-thaw events, using X-ray imaging.
With the collected data and deduced process understanding, it was possible to model and quantify the spatial and temporal development of snow packs. Furthermore, the field observations revealed how the interaction of tillage, state of the soils and snow cover at a certain time can lead to none or extensive surface runoff and soil erosion.
Integrating acquired data, observations and process knowledge facilitated advances in simulating and quantifying surface runoff and soil erosion rates across the catchment under investigation. The models applied and the maps and output derived are crucial elements for presenting current state and problems in the catchment to stakeholders (such as farmers), providing a starting point for discussing ways to prevent and reduce further runoff and erosion. For model calibration and validation, including interpretation of modelling results, good knowledge of the area and availability of detailed data are essential, especially when processes such as freezing-thawing of soils and ice layer and snow-pack dynamics have to be considered also.
In order to reduce runoff and soil erosion during winter and snowmelt conditions in the future, more targeted research is required in order to address the full range of existing knowledge gaps in this field, as identified in this particular study also.
Socio-economic and ecological characteristics of aquaculture in villages threatened by the sea in Demark District, North Java
Ariyati, W. ; Widowati, Lestari L. ; Bosma, R.H. - \ 2016
- 1 p.
socio economic - ecological - aquaculture - erosion - Demak
Pesticide use and off-site risk assessment : a case study of glyphosate fate in Chinese Loess soil
Yang, X. - \ 2016
Wageningen University. Promotor(en): Coen Ritsema; Violette Geissen, co-promotor(en): Hans Mol; Fei Wang. - Wageningen : Wageningen University - ISBN 9789462576759 - 152
pesticides - risk assessment - pesticide residues - glyphosate - loess soils - soil pollution - erosion - china - pesticiden - risicoschatting - pesticidenresiduen - glyfosaat - lössgronden - bodemverontreiniging - erosie - china
Pesticide use and off-site risk assessment: a case study of glyphosate fate in Chinese Loess soil
Abstract: Repeated applications of pesticide may contaminate the soil and water, threatening their quality within the environmental system and beyond it through water erosion related processes and leaching. Taking into account the situation of intense farming, pesticide use and erosion in China, and in the loess area in particular, this study aims to further the science of pesticide risk assessment by increasing the understanding of the fate of glyphosate and its main metabolite AMPA while also assessing their risks related to soil erosion in Chinese loess soil. Four main objectives are conducted:
1) Assessment of farmers’ knowledge and awareness of pesticide use in the Wei River catchment
In this study, we presented the information for the knowledge and awareness of pesticide risks via face-to-face interview among farmers (209) and retailers (20) in two rural regions (Qianyang County (S1) and Chencang County (S2)) of the Wei River catchment in China where the modes of farming and the state of erosion are very different. The results showed that farmers learned about the use and risk related to of pesticide use mainly by oral communication (p<0.01), rather than by introduction labelled on pesticide package bag/bottle and media tools (TV/newspaper/Internet/books). Protective measures were inadequate and washing hands (>70%) was the most common mode of personal hygiene after spraying, comparing to wearing masks, showering, and changing clothes. Regarding to dealing with the packages or containers of pesticide, farmers dumped them directly onto the land or into water, and over 85% of farmers claimed to use illegal pesticides. Compared to farmers, pesticide retailers were well-informed and highly conscious of their responsibility for the safe use of pesticides. Educational programmes targeted to age groups, proper disposal of pesticide waste, and sufficient supervision from authorities should consequently be considered for improving the levels of knowledge and awareness of the dangers of pesticides to human health and environmental pollution in the Wei River catchment, China.
2) Investigation of off-site transport of glyphosate and AMPA by runoff and erosion in Chinese loess soil
In this study, we assessed the short-term transport (1h duration, 1 mm min-1 rainfall) of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) related to erosion and runoff on bare loess soil with different slopes (10° and 20°)and application rates (3.6 kg ha-1 and 7.2 kg ha-1) in hydraulic flumes. Significant power and exponent function described a significantly negative relation between rainfall duration and the content of glyphosate and AMPA (p<0.01) in runoff and suspended load, respectively. The transport rate of glyphosate (including AMPA) by runoff and suspended load was approximately 4% and 10% of the applied amount, respectively indicating that it mainly underlies particulate transport. The glyphosate and AMPA content in the flume soil at the end of the experiment (after 1h) decreased significantly with depth (p<0.05), and 72, 2, and 3% of the applied glyphosate (including AMPA) remained in the 0-2, 2-5, and 5-10 cm soil layers, respectively. Thus, the risk of leaching was low. In view of loss of 14 % of the initially applied glyphosate after 1 h, “buffer zone”, referred as the protection area for ecosystem discharge between farming land and public rivers, is strongly recommended, especially in regions where rain-induced soil erosion is common.
3) Investigation of the on-site fate of glyphosate and AMPA formation in Chinese loess soil
In this study, we observed glyphosate decay, erosion and runoff related transport of glyphosate and AMPA at different slopes (10° and 20°) and application rates (3.6 kg ha-1 and 7.2 kg ha-1) under field condition during 35 d, September-October in 2012 (16.8±2.1°C with 35 mm rainfall in total) and July-August in 2013 (27 ± 2.3°C with 74 mm rainfall in total). The initial glyphosate decayed rapidly (half-life of 3.5 d) in the upper 2 cm of soil following a first-order rate of decay. AMPA content in the 0-2 cm soil layer correspondingly peaked 3 d after glyphosate application and then gradually decreased. The residues of glyphosate and AMPA decreased significantly with soil depth (p<0.05) independently of the slope inclination and application rate. About 0.36% of the glyphosate initially applied was transported off-site plots after one erosive rain 2 days after the application. Glyphosate and AMPA concentration in runoff were low while the contents in the sediment was much higher than in the upper 2 cm of the soil. This suggested that even though the transported glyphosate is limited, the off-site risk of glyphosate and AMPA is high. Consequently, a realistic erosion-pesticide model should be developed that can simulate the particulate-facilitated transport of glyphosate and its off-site risks involving decay processes.
4) Off-site risk assessment of particle-facilitated pesticide transport related to erosion
In this study, we have developed a parsimonious integrative model of pesticide displacement by runoff and erosion that explicitly accounts for water infiltration, erosion, runoff, and pesticide transport and degradation in soil. The conceptual framework was based on broadly accepted assumptions such as the convection-dispersion equation and lognormal distributions of soil properties associated with transport, sorption, degradation, and erosion. To illustrate the concept, a few assumptions are made with regard to runoff in relatively flat agricultural fields: dispersion is ignored and erosion is modelled by a functional relationship. A sensitivity analysis indicated that the total mass of pesticide associated with soil eroded by water scouring increased with slope, rain intensity, and water field capacity of the soil. The mass of transported pesticide decreased as the micro-topography of the soil surface became more distinct. The timing of pesticide spraying and rate of degradation before erosion negatively affected the total amount of transported pesticide. The mechanisms involved in pesticide displacement, such as runoff, infiltration, soil erosion, and pesticide transport and decay in the topsoil, were all explicitly accounted for, so the mathematical complexity of their description can be high, depending on the situation.
Overall, the outcome of this study indicates that it is urgent to improve farmers knowledge and awareness on pesticide use in order to reduce pesticide risks before they are applied in environmental system. The rapid decay of glyphosate to AMPA in loess soil suggests that on-site risks of glyphosate is mainly related to AMPA, especially under warmer climatic conditions. The off-site transport of glyphosate in our study was about 14% of the applied dose after 1 h of rainfall indicating that the off-site risks of glyphosate should be taken into account in regions highly prone to soil erosion. The concept of particulate transport elaborated in objective 4 should be incorporated in existing erosion models, such as LISEM, to predict off-site effects of glyphosate applications.
Roaming livestock distribution, densities and population estimates for St. Eustatius, 2013
Debrot, A.O. ; Hazenbosch, J.C.J. ; Piontek, S. ; Kraft, C. ; Belle, J. van; Strijkstra, A. - \ 2015
Den Helder : IMARES (Report / IMARES Wageningen UR C088/15) - 27
sint eustatius - vee - wilde dieren - populatiedichtheid - herkauwers - erosie - caribische eilanden - milieuafbraak - sint eustatius - livestock - wild animals - population density - ruminants - erosion - caribbean islands - environmental degradation
The problem of roaming livestock is a major impediment to agricultural development and nature conservation on St. Eustatius, as it also typically is on other islands in the region. In support of a government-led culling program, we here conducted a baseline study of livestock abundance and distribution on the island in the final quarter of 2013.
Effects of experimental stem burial on radial growth and wood anatomy of pedunculate oak
Copini, P. ; Decuyper, M. ; Sass-Klaassen, U.G.W. ; Gärtner, H. ; Mohren, G.M.J. ; Ouden, J. den - \ 2015
Dendrochronologia 33 (2015). - ISSN 1125-7865 - p. 54 - 60.
coastal dunes - white spruce - tree roots - erosion - netherlands - sediments - dynamics - plants - water
In dendrogeomorphology, abrupt changes in wood anatomy are frequently used to date the exact year of burial and exposure events. However, few studies have addressed the precision and underlying mechanisms of these changes. In a field experiment, performed in a drift-sand area in the Netherlands, we buried the stems of mature pedunculate oak trees (Quercus robur L.) up to a height of 50 cm and analysed the responses in ring width and earlywood-vessel characteristics, while monitoring the course of temperature above and below the soil surface. After 3 years of stem burial, we found no significant differences in ring width and earlywood-vessel characteristics between control and buried trees both above and below the burial level. Burial however strongly reduced temperature amplitude and the occurrence of sub-zero temperatures around the buried stems. All buried trees formed epitropic roots that grew upward into the new sediment layer, but no adventitious roots were formed on the buried stems. Irrespective of the burial treatments, we found that the mean ring width was largest at the original stem base and lowest at breast height. In contrast, vessel sizes were significantly larger at breast height compared with the stem base. Differences in vessel density barely differed between years and heights. In our field experiment on mature pedunculate oak trees, the burial of stems by 50 cm of drift sand did not induce any local growth suppression or detectable changes in wood anatomy. As wood-anatomical changes in response to burial have previously been reported for trees that had formed adventitious roots, we stress the role of adventitious-root formation as a possible trigger behind the local changes in wood anatomy, reflecting a functional change of a buried stem towards a root. Based on our field experiment, it seems unlikely that years of shallow or moderate burial events (=50 cm) can be reconstructed using the wood structure of buried stems. As epitropic roots develop quickly after burial, dating such roots may potentially yield better estimates of burial events. Further research on the relation between adventitious root and changes in stem anatomy is needed to ascertain the precision of dating sand-burial events using tree rings.
Unveiling soil degradation and desertification risk in the Mediterranean basin: a data mining analysis of the relationships between biophysical and socioeconomic factors in agro-forest landscapes
Salvati, L. ; Kosmas, C. ; Kairis, O. ; Karavitis, C. ; Hessel, R. ; Ritsema, C.J. - \ 2015
Journal of Environmental Planning and Management 58 (2015)10. - ISSN 0964-0568 - p. 1789 - 1803.
land-use change - abandonment - erosion - vulnerability - performance - indicators - region - europe - system - spain
Soil degradation and desertification processes in the Mediterranean basin reflect the interplay between environmental and socioeconomic drivers. An approach to evaluate comparatively the multiple relationships between biophysical variables and socioeconomic factors is illustrated in the present study using the data collected from 586 field sites located in five Mediterranean areas (Spain, Greece, Turkey, Tunisia and Morocco). A total of 47 variables were chosen to illustrate land-use, farm characteristics, population pressure, tourism development, rainfall regime, water availability, soil properties and vegetation cover, among others. A data mining approach incorporating non-parametric inference, principal component analysis and hierarchical clustering was developed to identify candidate syndromes of soil degradation and desertification risk. While field sites in the same study area showed a substantial similarity, the multivariate relationship among variables diverged among study areas. Data mining techniques proved to be a practical tool to identify spatial determinants of soil degradation and desertification risk. Our findings identify the contrasting spatial patterns for biophysical and socioeconomic variables, in turn associated with different responses to land degradation.
Co-evolution of soil and water conservation policy and human-environment linkages in the Yellow River Basin since 1949
Wang, F. ; Mu, X. ; Li, R. ; Fleskens, L. ; Stringer, L.C. ; Ritsema, C.J. - \ 2015
Science of the Total Environment 508 (2015). - ISSN 0048-9697 - p. 166 - 177.
sustainable land management - impact - framework - science - erosion - china - state
Policy plays a very important role in natural resource management as it lays out a government framework for guiding long-term decisions, and evolves in light of the interactions between human and environment. This paper focuses on soil and water conservation (SWC) policy in the Yellow River Basin (YRB), China. The problems, rural poverty, severe soil erosion, great sediment loads and high flood risks, are analyzed over the period of 1949–present using the Driving force–Pressure–State–Impact–Response (DPSIR) framework as a way to organize analysis of the evolution of SWC policy. Three stages are identified in which SWC policy interacts differently with institutional, financial and technology support. In Stage 1 (1949–1979), SWC policy focused on rural development in eroded areas and on reducing sediment loads. Local farmers were mainly responsible for SWC. The aim of Stage 2 (1980–1990) was the overall development of rural industry and SWC. A more integrated management perspective was implemented taking a small watershed as a geographic interactional unit. This approach greatly improved the efficiency of SWC activities. In Stage 3 (1991 till now), SWC has been treated as the main measure for natural resource conservation, environmental protection, disaster mitigation and agriculture development. Prevention of new degradation became a priority. The government began to be responsible for SWC, using administrative, legal and financial approaches and various technologies that made large-scale SWC engineering possible. Over the historical period considered, with the implementation of the various SWC policies, the rural economic and ecological system improved continuously while the sediment load and flood risk decreased dramatically. The findings assist in providing a historical perspective that could inform more rational, scientific and effective natural resource management going forward.
Short- to mid-term impact of conservation agriculture on yield variability of upland rice: evidence from farmer's fields in Madagascar
Bruelle, G. ; Naudin, K. ; Scopel, E. ; Domas, R. ; Rabeharisoa, L. ; Tittonell, P.A. - \ 2015
Experimental Agriculture 51 (2015)1. - ISSN 0014-4797 - p. 66 - 84.
cropping systems - tillage systems - maize productivity - soil - erosion - africa - degradation - nigeria - surface - runoff
Family farming in the tropics suffers from low crop productivity mainly due to a combination of poor soil fertility, low investment capacity, and a variable climate. The Lake Alaotra region of Madagascar is no exception and rainfed production is particularly hard hit. To evaluate the agronomic benefits of conservation agriculture (CA) in a region of erratic rainfall, we analysed four years of yield, management and climatic data from 3803 upland rice fields cultivated by farmers and monitored by researchers. Fields located on rainfed lowlands and hillsides were cultivated with sole rice using conventional tillage (Cv) or rice sown with no-tillage on dead organic mulch and rotated with other cereal/legume combinations (CA) from 2006 to 2011. A first global comparison across seasons, locations and years of adoption showed significantly higher average yields under CA, with no change in variance (on lowland: 2.6 ± 0.9 t ha–1 Cv, 2.8 ± 0.9 t ha–1 CA; on hillside: 2.1 ± 0.8 t ha–1 Cv, 2.4 ± 0.8 t ha–1 CA). Grouping fields according to the number of years under CA (first to fourth) revealed that CA gradually increased average yields and reduced the coefficient of variation in the short and mid-term (on lowland: +0.2 t ha–1 and –6% coefficient of variation; on hillside: +0.7 t ha–1 and –13% coefficient of variation, over four to six years of successive CA cropping). The average yield increase under CA was not associated with an increase in mineral fertiliser use, as farmers used the same amounts of fertilisers (or none) under Cv and CA. The comparison Cv versus CA also highlighted a major benefit of CA regarding climate: it widened the window of possible sowing dates. A classification and regression tree analysis of the entire dataset revealed that rice yield was more affected by agro-environmental factors than management factors (fertilisation, Cv or CA), and extreme climate variability such as the severe drought of 2007–2008 could not be offset by CA. The hypothesis of yield penalties during the first years of implementation of CA cannot be verified with the evidence presented in this study.
Changes in agricultural land use affecting future soil redistribution patterns: A case study in southern tuscany (ITALY)
Debolini, M. ; Schoorl, J.M. ; Temme, A.J.A.M. ; Galli, M. ; Bonari, E. - \ 2015
Land Degradation and Development 26 (2015)6. - ISSN 1085-3278 - p. 574 - 586.
ne spain - landscape evolution - driving forces - sediment yield - erosion - model - management - region - abandonment - catchment
Land-use changes (LUCs) can be defined as the result of the direct action of the stakeholders in a particular area and natural or human driving forces. LUCs can influence various processes within the landscape and can have an impact on landscape functions. An analysis of the impact of LUCs on landscape processes can help to focus future rural policies. LUCs in Mediterranean areas particularly affect landscape functions because of their agro-pedoclimatical characteristics. The aims of this work are as follows: (i) to characterise LUCs in the last 11¿years in a typical Mediterranean area, the Trasubbie river basin (southern Tuscany, Italy); (ii) to extrapolate these changes and create spatially explicit LUC scenarios for the near future; and (iii) to simulate how and where the predicted LUCs may affect soil redistribution. We carried out an analysis of LUCs within the study area and used the trends to propose alternative scenarios for 2013. For these years, we spatially allocated land use (using the Conversions of Land Use and its Effects model) and used a landscape process model (landscape process modelling at multi-dimensions and scales) to assess soil redistribution patterns. Land use in the study area changed almost linearly between 1996 and 2007, with cereals and annual fodder crops decreasing, and vineyards, perennial pastures and land abandonment increasing. Our LUC scenario extrapolates these dynamics to make predictions for 2013. A comparison of LAPSUS results between LUC and baseline scenarios for 2013 showed an increase in terms of net soil loss and total erosion, and a decrease in terms of sediment delivery ratio.
Hydrological services and the role of forests: Conceptualization and indicator-based analysis with an illustration at a regional scale
Carvalho-Santos, C. ; Honrado, J.P. ; Hein, L.G. - \ 2014
Ecological Complexity 20 (2014). - ISSN 1476-945X - p. 69 - 80.
amplifies flood risk - ecosystem services - water yield - vegetation changes - developing-world - global evidence - land-use - catchment - erosion - afforestation
Forests are among the most important ecosystems for the provision of hydrological services. These include water supply and water damage mitigation, in the dimensions of quantity, timing and quality. Although the hydrological role of forests is well documented in the literature, a conceptual framework integrating these three dimensions is still missing. In this study, a comprehensive conceptual framework to improve the assessment of hydrological services provided by forests was developed. In addition, the framework was tested by an illustration for northern Portugal, a region with both Mediterranean and Atlantic climatic influences. The TEEB (The Economics of Ecosystems and Biodiversity) framework of ecosystem services was adapted to the relation between forests and water. Then, this new framework was complemented with a set of spatially-explicit indicators that quantify the supply and demand of hydrological services. In addition, the implications of the framework were discussed in the context of the social-ecological systems, using the DPSIR (Drivers, Pressures, State, Impacts, and Responses) model. Finally, the framework and the indicators were illustrated for northern Portugal using the water supply (quantity) and soil erosion control as examples. Results show that the proposed conceptual framework is a useful tool to support land planning and forest management, adapting the provision of hydrological services to the regional biophysical and social conditions. The test of the framework across a heterogeneous region suggests that a spatially explicit combination of system property, function, service and benefit indicators can be an effective way of analysing and managing the supply and demand of the hydrological services. (C) 2014 Elsevier B.V. All rights reserved.
Attribution of climate change, vegetation restoration, and engineering measures to the reduction of suspended sediment in the Kejie catchment, southwest China
Ma, X. ; Lu, X. ; Noordwijk, M. van; Li, J.T. ; Xu, J.C. - \ 2014
Hydrology and Earth System Sciences 18 (2014). - ISSN 1027-5606 - p. 1979 - 1994.
upper yangtze-river - loess plateau - nonparametric-tests - water-quality - yellow-river - swat model - check dams - load - impacts - erosion
Suspended sediment transport in rivers is controlled by terrain, climate, and human activities. These variables affect hillslope and riverbank erosion at the source, transport velocities and sedimentation opportunities in the river channel, and trapping in reservoirs. The relative importance of those factors varies by context, but the specific attribution to sediment transfer is important for policymaking, and has wide implications on watershed management. In our research, we analyzed data from the Kejie watershed in the upper Salween River (Yunnan Province, China), where a combination of land cover change (reforestation, as well as soil and water conservation measures) and river channel engineering (sand mining and check dam construction) interact with a changing climate. Records (1971–2010) of river flow and suspended sediment loads were combined with five land-use maps from 1974, 1991, 2001, 2006 and 2009. Average annual sediment yield decreased from 13.7 t ha-1 yr-1 to 8.3 t ha-1 yr-1 between the period 1971–1985 and the period 1986–2010. A distributed hydrological model (Soil and Water Assessment Tools, SWAT) was set up to simulate the sediment sourcing and transport process. By recombining land-use and climate data for the two periods in model scenarios, the contribution of these two factors could be assessed with engineering effects derived from residual measured minus modeled transport. Overall, we found that 47.8% of the decrease was due to land-use and land cover change, 19.8% to climate change, resulting in a milder rainfall regime, 26.1% to watershed engineering measures, and the remaining 6.3% was due to the simulation percent bias. Moreover, mean annual suspended sediment yield decreased drastically with the increase of forest cover, making diverse forest cover one of the most effective ecosystems to control erosion. For consideration of stakeholders and policymakers, we also discuss at length the modeling uncertainty and implications for future soil and water conservation initiatives in China.
Evaluation and Selection of Indicators for Land Degradation and Desertification Monitoring: Methodological Approach
Kosmas, C. ; Karis, O. ; Karavitis, C. ; Ritsema, C.J. ; Salvati, L. ; Acikalin, S. ; Alcala, S. ; Alfama, P. ; Atlhopheng, J. ; Barrera, J. ; Belgacem, A. ; Sole-Benet, A. ; Brito, J. ; Chaker, M. ; Chanda, R. ; Coelho, C. ; Darkoh, M. ; Diamantis, I. ; Ermolaeva, O. ; Fassouli, V. ; Fei, W. ; Fernandez, F. ; Ferreira, A. ; Gokceoglu, C. ; Gonzalez, D. ; Gungor, H. ; Hessel, R. ; Juying, J. ; Khatteli, H. ; Kounalaki, A. ; Laouina, A. ; Lollino, P. ; Lopes, M. ; Magole, L. ; Medina, L. ; Mendoza, M. ; Morais, P. ; Mulale, K. ; Ocakoglu, F. ; Ouessar, M. ; Ovalle, C. ; Perez, C. ; Perkins, J. ; Pliakas, F. ; Polemio, M. ; Pozo, A. ; Prat, C. ; Qinke, Y. ; Ramos, A. ; Riquelme, J. ; Romanenkov, V. ; Rui, L. ; Santaloia, F. ; Sebego, R. ; Sghaier, M. ; Silva, N. ; Sizemskaya, M. ; Soares, J. ; Sonmez, H. ; Taamallah, H. ; Tezcan, L. ; Torri, D. ; Ungaro, F. ; Valente, S. ; Vente, J. de; Zagal, E. ; Zeiliguer, A. ; Zhonging, W. ; Ziogas, A. - \ 2014
Environmental Management 54 (2014)5. - ISSN 0364-152X - p. 951 - 970.
mediterranean conditions - aggregate stability - soil properties - rock fragments - organic-matter - vegetation - tillage - biomass - erosion - greece
An approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification risk, a total of 70 candidate indicators was selected providing information for the biophysical environment, socio-economic conditions, and land management characteristics. The indicators were defined in 1,672 field sites located in 17 study areas in the Mediterranean region, Eastern Europe, Latin America, Africa, and Asia. Based on an existing geo-referenced database, classes were designated for each indicator and a sensitivity score to desertification was assigned to each class based on existing research. The obtained data were analyzed for the various processes of land degradation at farm level. The derived methodology was assessed using independent indicators, such as the measured soil erosion rate, and the organic matter content of the soil. Based on regression analyses, the collected indicator set can be reduced to a number of effective indicators ranging from 8 to 17 in the various processes of land degradation. Among the most important indicators identified as affecting land degradation and desertification risk were rain seasonality, slope gradient, plant cover, rate of land abandonment, land-use intensity, and the level of policy implementation.
Measurement uncertainties in quantifying aeolian mass flux: evidence from wind tunnel and field site data
Poortinga, A. ; Sterk, M. ; Visser, S.M. - \ 2014
erosion - Aeolian sediment transport
This dataset contains data from two different studies on aeolian sediment transport. The first study was conducted in Dori, Burkina Faso, the second at Ameland, the Netherlands. The first dataset contains data from a degraded (deg), dune and valley site for 11 events. The second dataset contains data of 18 catchers for 6 different events.
Soft engineering vs. a dynamic approach in coastal dune management: a case study on the North Sea barrier island of Ameland, the Netherlands
Jong, B. de; Keijsers, J.G.S. ; Riksen, M.J.P.M. ; Krol, J. ; Slim, P.A. - \ 2014
Journal of Coastal Research 30 (2014)4. - ISSN 0749-0208 - p. 670 - 684.
hoogwaterbeheersing - kustbeheer - duinen - eolische processen - geologische sedimentatie - nederlandse waddeneilanden - flood control - coastal management - dunes - aeolian processes - geological sedimentation - dutch wadden islands - dutch coast - beach - foredunes - erosion - storms
Dunes act as flood defences in coastal zones, protecting low-lying interior lands from flooding. To ensure coastal safety, insight is needed on how dunes develop under different types of management. The current study focuses on two types of coastal dune management: (1) a “soft engineering” approach, in which sand fences are placed on the seaward side of foredunes, and (2) “dynamic coastal management,” with minimal or no dune maintenance. The effects of these management styles on dune formation are examined for two adjacent coastal sections of the North Sea barrier island of Ameland, The Netherlands, where dynamic coastal management was introduced in 1995 and 1999, respectively.
Dunes act as flood defenses in coastal zones, protecting low-lying interior lands from flooding. To ensure coastal safety, insight is needed on how dunes develop under different types of management. The current study focuses on two types of coastal dune management: (1) a "soft engineering" approach, in which sand fences are placed on the seaward side of foredunes, and (2) "dynamic coastal management," with minimal or no dune maintenance. The effects of these management styles on dune formation are examined for two adjacent coastal sections of the North Sea barrier island of Ameland, The Netherlands, where dynamic coastal management was introduced in 1995 and 1999, respectively. For each section, we analyzed cross-shore profile data from 1980 until 2010, deriving dune foot position, crest position, crest height, and foredune volume for each year and analyzing the situation before and after the change in management. We further assessed the effect of the management regime on dune vegetation. Other factors that could influence dune development were also taken into account, such as beach width and shape, water levels, wave heights, and nourishments. Results show that implementation of dynamic coastal management did not directly affect the volume of the foredune. Growth was occasionally interrupted, coinciding with high-water events. In periods between erosive storms, dune growth rates did not show a significant difference between management types (p = 0.09 and 0.32 for sections 1 and 2, respectively). The main effect of the change was on vegetation development. Dynamic coastal management, therefore, did not reduce coastal safety.