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The Mediterranean mountainous landscapes have undergone large-scale exploitation for millennia. In the Central Pyrenees, land abandonment has occurred since the 1950s, leading to a process of woody encroachment. The main objective of this paper is to shed light on the effects of different land use and land covers (LULCs) on soil organic carbon (SOC) and nitrogen (N) stocks, and on the composition of soil organic matter (SOM) after land abandonment in the Central Pyrenees. Five LULCs (8 specific sites) were selected through detailed land use change mapping. Soil and litter samples (n = 160) were collected and analyzed, including Tetramethylammonium hydroxide pyrolysis–gas chromatography. Organic carbon (Corg)/N ratios, Carbon Preference Index and Average Chain Length indices were calculated based on the distribution of fatty acids in order to determine the molecular composition and degradation of SOM. The results showed: (i) an increase in the dominance index and forest cover, at the expense of shrublands and agricultural fields, and a decrease in Shannon’s Diversity and Evenness indexes; (ii) LULC and depth had significant effects on SOC and N contents and stocks; (iii) SOC and N contents and stocks were higher in the meadows and young forests; (iv) significant differences were observed between meadows and young forests and the first stages of land abandonment considering the soil profile; (v) total decomposition of lignins and an omnipresence of unsaturated and saturated straight-chain fatty acids; and (vi) Corg/N values indicate that the origin of SOM is microbial. This study confirms that SOC accumulation after abandonment is a slow process, and the first stages of the woody encroachment decrease SOC stocks. Woody encroachment should be managed with measures based on scientific knowledge, but also considering the historic adaptation of agro-pastoral activities to the environment to ensure the proper functioning of ecosystem services and promote SOC storage in Mediterranean mountain soils.

Soil erosion by water from arable land poses a serious threat to on-field agricultural productivity and the wider environment through off-site damage. Multiple studies show that climate change will worsen the impacts of soil erosion in various regions. However, these studies are limited by (1) the lack of any thorough evaluation process in applying climate scenarios to drive soil erosion models, and (2) the failure to consider the role of changing land use under future climate change, despite the evidence that it is more important than rainfall changes in driving increased erosion. Using the WEPP soil erosion model, these methodological gaps are addressed in this study for a small catchment in Belgium that is both heavily impacted by soil erosion and boasting an extensive array of mitigation measures. We develop a novel and comprehensive methodology to rigorously and efficiently select suitable climate models specifically for simulating soil erosion by water, and examine the impact of a range of environmentally and economically viable land use choices on soil erosion. The main findings reveal that our climate model selection methodology is successful in generating the widest range of likely future scenarios from a small number of models, compared with other selection methods. Our novel methodology reveals that the magnitude and frequency of soil erosion events will increase considerably under the mean of all scenarios between 2041 and 2100 with existing land management. Winter wheat represents the most economically and environmentally viable land use choice to effectively mitigate future soil erosion when compared to other land use alternatives under the full range of likely future climate scenarios. This research illuminates the importance of carefully tuned climate model selection and land use changes for modelling future soil erosion by water so the best- and worst-case scenarios can be adequately prepared for under a changing climate.

Forest plantations with exotic species are planted extensively in the southern hemisphere for soil conservation and shallow landslide mitigation. The extent to which these are suitable for fulfilling their protection goals is the subject of debate. A biogeomorphic framework was applied to link land use, soil conservation and natural hazards. It consists of a feedback loop with the two effect pathways hillslope stability and vegetation fitness. The study site is located in Chilean Patagonia, where thixotropic Andosols are widespread and Pinus plantations were planted initially in conservation areas, and later on private land. We were testing the hypothesis whether soil stability differs between primary and secondary forests, Pinus plantations, wildfire sites (ex. plantations) and pastures. Shear strength, liquid limit, consolidation degree and available water capacity were used as soil stability indicators and set as dependent variables using non-metrical multidimensional scaling (NMDS), representing mechanical and hydrological biogeomorphic interactions. Soil texture, topographic and vegetation properties were post-hoc correlated as independent variables. Vegetation assemblage correlates most strongly with soil indicator variance. The soils under secondary native Nothofagus forests have significantly higher liquid limits than Pinus plantations (41 ± 4.9% vs. 31 ± 14%, p < 0.1, A Horizon). Consolidation degree is higher under secondary forests than in Plantations (A and B Horizon), due to a significantly higher root abundance. Primary forests provide landscape by maintaining the water cycle balance and biodiversity. Secondary forests establish the biogeomorphic feedback loop through mechanical effects and enhancing vegetation fitness. Pinus plantations cause a slight improvement in soil stability properties, but with trade-offs in water balance and vegetation fitness. Landscape resilience is thus impaired by the higher risk of wildfires, erosion and landslides. Pastures show good values in the soil stability parameters, but their biogeomorphic interactions are unlikely to rebuild landscape resilience.

© 2019 The Author(s) Gully erosion is one of the main causes of land degradation, particularly in the drought-prone regions of Ethiopia. This study assessed spatio-temporal changes of gully length and density in watershed pairs in Guder, Aba Gerima, and Dibatie sites, which are representative highland, midland, and lowland agro-ecologies in the Upper Blue Nile basin of Ethiopia. Aerial photographs (1957, 1982) and very high resolution satellite images (QuickBird, IKONOS, Worldview-2, SPOT-7, and Pleiades) of the six watersheds, along with field survey results, were used in the analyses. The aerial photographs were scanned and orthorectified using ENVI 4.3 image analysis software, and gullies were mapped by visual image interpretation in the ArcGIS environment. Rates of increase in gully length in Guder (36.9 m yr −1 ) and Aba Gerima (33.6 m yr −1 ) were almost double the rate in Dibatie (17.8 m yr −1 ) from 1957 to 2016 or 2017, and over the same period, gully density similarly increased by 5.9, 5.4, and 3.7 m ha −1 in Guder, Aba Gerima, and Dibatie, respectively. The higher rates in Guder and Aba Gerima reflect the long history of cultivation and human settlement in those sites, whereas agricultural activity became widespread in Dibatie only after implementation of the national resettlement program in the 1980s. Moreover, although gully density tended to increase over time in all six watersheds, in the three watersheds (one in each paired watershed) where soil and water conservation measures had been introduced, the rate of increase was lower than in those where no such measures were implemented. In addition, gully distribution was linked to land use and landscape position; gully density was higher in cultivated areas and where slope gradients were gentle. The results of this study indicate that careful site-specific identification of factors controlling gully initiation and development is crucial so that appropriate management strategies can be developed for these three sites and for other areas with similar agro-ecologies in the Upper Blue Nile basin. ispartof: CATENA vol:179 pages:160-174 status: published

Topography is one of the key factors controlling soil erosion and redistribution of pedogenic material along slope. Land cover change can have an accelerating or retarding impact on topographically-controlled soil erosion rates, depending on the type and intensity of land use and management. In this study, we investigated the combined effect of hillslope gradient and land cover change on soil redistribution and rejuvenation in a subtropical region where Atlantic rain forest was converted to agricultural land. We used a two versus two factorial design, and evaluated the effect of hillslope gradient (steep vs. gentle) and land cover (forest vs. cropland) on the spatial pattern of soil weathering degree along slope. In four soil toposequences, soil weathering indices (Total Reserve in Bases, Chemical Index of Alteration, clay content, iron oxide content) and mineralogical assemblages were used to express genetic and morphological differences among soil profiles. Our data showed that the spatial differentiation in chemical weathering degree along slope is strongly dependent on the hillslope gradient: while the gentle slopes show negligible differences in chemical weathering degree along slope, the steep slopes show clear spatial differences. Besides, there is an interaction effect between hillslope gradient and land cover. Forest conversion to cropland enhances erosion-driven soil redistribution with a marked effect on soil rejuvenation along steep slopes but no clear effect along gentle slopes. The comparative study based on four toposequences highlights that accelerated soil erosion after conversion of forests to cropland has further enhanced lateral soil fluxes and redistribution of topsoil material along steep slopes, and led to soil rejuvenation and exposure of less weathered soil material at the eroding sites.

Termite mounds influence ecosystem heterogeneity and contribute to the stabilization of the system under global change. A number of environmental factors influence the distribution, height, diameter and designs of termite mounds but these factors are not only poorly understood, they cannot be extrapolated for everywhere. In this study, we employed a ground based survey and Geographical Information System (GIS) technique to map 156 km2 study area in Keffi, Nigeria. The aims were to (1) estimate the density and area covered by termite mounds, (2) sample and identify species types and how they are distributed, and (3) use five environmental factors (elevation, geology, surface water drainage, land use/land cover and static water level) to model suitable sites for mounds construction. A total of 361 mounds were mapped representing a density of about 0.8 mounds ha−1 and covering only about 0.31% of the studied area. Next, the effect of the five chosen environmental factors on the geographic distribution, life status, height and diameter of mounds and species diversity were analysed and their relationships plotted in pairwise comparison matrices using the Saaty's Analytical Hierarchy Process. Normalized rates for classes in each factor and corresponding weights were computed and aggregated using the Weighted Linear Combination method. The result depicted that moderate to low elevation (270–330 m amsl), rock cover types that are more susceptible to weathering (schist), cultivated areas and shallow water table zones are most favourable for termites to build mounds. The result obtained in this study shows a promising correlation between the environmental factors and termite mounds distribution. The proposed model can easily be replicated in a different but similar multi-land use and rock cover types.

Land inundation is a common occurrence in Bangladesh, mainly due to the presence of two major river systems – the Brahmaputra and the Ganges. Inundation influences land use and cropping intensity. However, there is little information on the influences of the extent of flooding and cropping intensity has on soil organic carbon (SOC), particularly at the landscape level. To investigate these influences, we collected 268 surface (0–30 cm) soil samples from 4 large sites within the two alluviums deposits (the Brahmaputra river and the Ganges river), on a regular grid (1600 m). The findings show that SOC levels are generally low, reflecting the intensity of agriculture and land management practices. SOC variability was higher across the medium high land (MHL) and medium low land (MLL) sites than in the high land (HL) and low land (LL) sites. The relatively low SOC levels and variability in the HL sites indicate soils here might have reached to equilibrium levels due to higher land use intensity. Topographically higher lands (HL and MHL), due to less of inundation, had higher cropping intensities and lower SOC's than lower lands (MLL and LL), which had lower cropping intensities, as they remain inundated for longer periods of time. The findings clearly demonstrate the intrinsic influence of land inundation in driving cropping intensity, land management practices and SOC levels.

12 Pags.- 5 Tabls.- 5 Figs., Several decades of intensive rainfed farming in Mediterranean mountains and later land abandonment has led to rapid land use and land cover changes. During recent centuries, the conversion of rangelands into croplands has increased the surfaces prone to erosion. In the southern Pre-Pyrenees, the process was reversed during the middle of the twentieth century, allowing the recovery of vegetation and subsequent variation in land cover. This work aims to assess how land use changes after generalised land abandonment affect some major soil properties related to soil quality. For this purpose, 98 replicate bulk soil samples were collected in a 23 km2 catchment that was mostly cultivated at the beginning of the last century. Soil samples were distributed over areas representing the main land uses (agricultural land, natural forest, pine afforestation and scrubland). Bulk density, stoniness, grain size, pH, carbonates, electrical conductivity, soil organic carbon (SOC), total nitrogen (TN), water retention capacity and magnetic properties (low frequency magnetic susceptibility (LF) and frequency dependence (FD)) were analysed in the samples from different land use areas. A past scenario was recreated using estimated data from the SPEROS-C model in order to evaluate changes in SOC over time. Furthermore, a multitemporal analysis of the Normalised Difference Vegetation Index of Landsat images was performed between 1972 and the present in order to assess the dynamics of revegetation. After land abandonment, 16.5% of the area remained as croplands, but afforestation and natural revegetation occupied 83.5% of the catchment. The highest mean value for SOC was found in the pine afforested area and the highest TN mean value was found in the natural forest. The lowest mean values for SOC and TN were recorded on the agricultural land. These results show the impact of soil changes produced by land use changes in fragile Mediterranean mountain agroecosystems., This research was financially supported by the project TRAZESCAR (CGL2014-52986-R) with the aid of a predoctoral contract (BES-2015-071780) funded by the Spanish Ministry of Science, Innovation and Universities.

Inland river terminal lakes help maintain the regional ecological environment. However, terminal lakes in arid regions have shrunk dramatically over the past 50 years. We extracted the water areas of Taitema Lake in the arid region of Central Asia and calculated the fractional vegetation coverage (FVC) of the surrounding areas based on Landsat images from 1989 to 2019. We analysed the evolution and driving factors of the FVC and lake area before and after implementing an ecological water conveyance (EWC) project in 2000. The contributions of the driving factors were derived using regression analysis, and the effect coefficients were calculated with a path analysis. Results showed that before EWC (1989–1999), Taitema Lake was dry, the proportions of medium and high FVC areas were small, and FVC varied moderately. The contributions of land use and inflow water from Qarqan River to the regional FVC were 57.4% and 45.3%, respectively, and the effect coefficients of temperature and precipitation on FVC were 0.09 and 0.02, respectively. Human-dominated land-use change was the main factor affecting FVC change. After EWC (2000–2019), the water in Taitema Lake was restored, and the average annual proportions of medium and high FVC were 9.5% and 2.7% higher than the pre-EWC period, respectively. The contributions of land use and river inflow to the water area were 39.1% and 60.9%, and those to FVC were 40.7% and 59.3%, respectively. Precipitation had a slightly stronger effect on the water area and FVC than the temperature in the study area, whereas the influence of river inflow on the water area and FVC was less evident than that of the EWC. EWC can replenish lake water quickly, which is essential for improving the ecological environment of terminal lake areas.

Land use change is affected by many driving factors such as the economy, population, and government policy. This study investigated the relationship between government policy and land use change to develop an understanding applicable to the formulation of strategies for sustainable land use. The Lijiang River Basin in the Guangxi Zhuang Autonomous Region in southern China was selected for this study. The predicted characteristics of land use change were explored using the CLUE-S numerical model and logistic regression. Using Landsat remote sensing imagery as source data, we simulated the tendency of land use change from 1993 to 2020 under two scenarios: a Natural Growth Scenario (NS) and a Government Intervention Scenario (GS), and we analyzed the possible social driving factors. The results revealed that from 1993 to 2015, both construction and cultivated land have shown a tendency of areal increase. Water and woodland areas both decreased from 1993 to 2006 but then they increased dramatically from 2006 to 2015. Shrubland areas increased from 1993 to 2006 but decreased slightly from 2006 to 2015. The CLUE-S model was used to predict the spatial patterns of land use for 2020. It showed that under the NS, the areas of construction and cultivated land increased, while the areas of other land uses decreased. Under the GS, the areas of construction land, woodland, cultivated land, and water all increased, while the areas of the others declined. Furthermore, the area of woodland decreased for every county under the NS, but areas of woodland expansion were located in Lingchuan and Lingui counties under the GS. Hotspots of cultivated land occurred in Lingchuan County under the NS and in Xingan County under the GS. Water area decreased in every county under the NS, whereas increases in water areas occurred in Lingchuan and Guilin counties under the GS. Construction land expanded in Lingchuan County under the NS and in Guilin County under the GS. The Returning Farmland to Forest Program could be considered a successful addition to the eco-environmental policies implemented in the Lijiang River Basin.

Phosphorus (P) is often a limiting nutrient that leads to the eutrophication of aquatic systems. While dissolved P forms are the most bioavailable, the form, mobility, transport and fate of P are directly related to its association with fine-grained riverine sediment. Therefore, to implement successful P catchment management strategies it is important to understand the relative contribution of different sediment sources to P loads across the river continuum. While agricultural topsoil and, to a lesser extent, riverbed sediment are important sources of sediment-associated P, channel banks have been shown to be an important sediment source in some catchments. However, comparatively little is known about the P concentration and corresponding spatial variability in channel bank sediment and the associated implications for catchment management. The present study examines the spatial variability of P associated with channel bank profiles within a series of three nested catchments using both non-spatial and spatial statistical methods, where for the latter, a novel spatial approach was used to estimate the spatial averages and variances of P in channel bank sediment along the stream network. Channel bank P concentrations were compared to factors such as catchment scale, stream order, land use, bank exposure and location along the stream network. Concentrations of TP ranged between 129.6 and 1206.9 mg P kg−1 of which the water extractable P (WEP) content ranged from 0.01 to 0.12%. Stream order was found to influence TP concentrations, while land use and catchment scale provided only a moderate influence. This suggested that focussing channel bank sampling strategies at the largest catchment scale would capture key drivers of TP variability provided stream order is sufficiently represented. Whether the bank was had limited vegetation and was exposed and potentially eroding had a slight influence on TP variability in second-order stream banks in the larger of the two nested catchments. However, the slightly lower TP concentrations measured at these sites indicated that banks that are actually eroding may be contributing less TP than the total channel bank TP values measured across the catchments as a whole. The results of an explicitly spatial analysis demonstrated that local channel bank TP averages and TP variances vary along the stream network. Specifically, the most accurate spatial predictor of TP was local TP means with the use of ‘crow flies’ rather than stream network distances. Local TP variances were used to provide optimal designs for future channel bank TP sampling campaigns, given available resources. Throughout, both standard and outlier-resistant statistical analyses were applied to improve interpretation of the study findings.

The paramos biome of the northern Andes is a collection of high-mountain tropical grassland wetland ecosystems that provides important ecosystem services including hydrological buffering and water supply. Human activities in these ecosystems transform vegetation cover and soil hydro-physical properties, affecting their hydrological performance and water quality and quantity. Here, we conducted a systematic review on the influence of land use (agriculture, livestock grazing, and afforestation) on the hydro-physical properties of paramo soils and analyzed its implications for streamflow buffering. Our review protocol identified 32 relevant papers, from which key hydro-physical properties linked to streamflow variability were available: soil organic matter (SOM), soil organic carbon (SOC), porosity, bulk density, saturated hydraulic conductivity, and water retention capacity (WRC). The analysis shows that soils with native cover are characterized by a porous structure that allows a high WRC and SOM content. Agriculture increases macroporosity but it leads to bare fallow plots that promote loss of nutrients and SOM. Burning generates hydrophobic aggregates that affect WRC. Livestock grazing produces soil compaction and increases bulk density, reducing infiltration and WRC. Lastly, afforestation with exotic species (e.g. pines, eucalyptus) decreases SOM and WRC by changing soil structure. In general, the analyzed land-use activities generate hydrophobic aggregates, increase bulk density, promote erosion and runoff, and impair hydrological buffering capacity. This integrated evidence from multiple empirical studies can be used to effectively communicate the effects of different land use practices on paramo soils, provide information for modelling in data-scarce situations, and contribute to decision making processes for land use planning and conservation.

Farmland abandonment in Europe is a major problem because of environmental, socioeconomic and landscape implications. In this paper, a general view of the extent of abandoned land, the stages of abandonment and the drivers that manage this process in Europe is presented. A scientific literature review shows an abandonment at the beginning of the 19th century, although the largest abandonment in terms of area took place in the mid-20th century. This abandonment had a far greater impact on mountain areas because of rural depopulation as well as biophysical constraints. Since the last decades of the 20th century, abandonment driven by the CAP in European Member States and by the end of the communist regime in Central and Eastern Europe has been taking place. This abandonment affects peripheral marginal areas due to biophysical or socioeconomic conditions. Semi-arid areas in Southern Europe have also seen an important extent of abandoned land over the last few decades. The literature draws on the ongoing abandonment from the following decades, and 3–4% of current farmland is considered to be affected. It is noted that, among the drivers, external factors (migration, socioeconomic model, public policies, etc.) act as enhancers that emphasize land abandonment. However, internal causes (agro-ecological and socioeconomic factors and also the features of agricultural holdings) control the dynamics and the extent of this phenomenon. The international literature about land abandonment in Europe is vast, and most of the specialized production is devoted to the effects of land abandonment, while few works determine the extent, stages and drivers of land abandonment. Finally, it is necessary to review the grey literature to obtain more quantitative information on the amount of abandoned land in Europe.

Land degradation and soil erosion are key environmental problems in Mediterranean mountains characterized by both a long history of human occupation, and strong seasonality of hydrological regimes. Experimental monitored catchments have identified main controlling factors on erosion dynamics, but because of the short time span of the instrumental measurements they do not integrate the complete temporal and spatial variability of these environments. To obtain some long-term series of Mediterranean landscape evolution we propose a novel strategy based on multi-proxy analyses of lake sediments aimed to quantify sediment delivery and erosion dynamics. Karstic lakes in the Iberian Range (Central Spain) provide an opportunity to reconstruct the depositional evolution of the watersheds and to evaluate the response to both, the variable anthropogenic impacts and climate forcings during the last 1000. years.The most significant periods of increased sediment delivery (26-483Tkm yr-1) in the Iberian Range sites took place during the 15th-16th and 18th-19th centuries as a result of large land use changes and land clearing. Positive synergies between increasing human population and more humid periods led to peaks in sediment deliver during some phases of the Little Ice Age. Recent changes associated with the rural exodus and land abandonment during mid-20th century are more clearly shown in larger watersheds by decreased sediment delivery to the lakes due to the re-vegetation of the landscape (6-200Tkm yr-1).This new integrated approach based on long-term lake sequences provides a longer perspective of erosion processes in Mediterranean watersheds and validates the main factors identified in monitoring surveys (land cover and surface formations erodibility). In both settings, lakes and experimental catchments, most sediment delivery occurs during flooding events. Measured and reconstructed values show comparable large ranges, underlying the punctuated nature of sediment dynamics in Mediterranean landscapes at decadal and centennial scales. © 2016 Elsevier B.V., This research was supported by the GLOBALKARST (CGL2009-08415) project funded by the Spanish Ministry of Economy and Competitiveness and by the I-LINK program (I-LINK0510) funded by the CSIC. F. Barreiro-Lostres acknowledges the ‘JAE-PreDoc’ predoctoral contract co-funded by C.S.I.C. and the European Social Fund.

Land use and land cover (LULC) change impacts on hydrology and water quality are of critical importance in regions where water quality is degraded. One such location is the Mississippi Delta in the United States, where widespread agriculture across the landscape is a major contributing source to sediment- and nutrient-heavy runoff. To address how the landscape has changed in the recent past and consider how it may continue to change in the future, we analyzed the temporal and spatial variability of the LULC changes (e.g. forest, cropland, corn and soybean) in the Big Sunflower River Watershed. We applied these LULC changes in the Soil and Water Assessment Tool (SWAT) model to demonstrate the impacts on stream discharge, total suspended sediments (TSS) concentrations, total nitrogen (TN), and total phosphorus (TP) yields. Model performance was considered satisfactory to good (R2 = 0.46–0.88, NSE = 0.34–0.64) for all simulated water quantity and water quality parameters. TSS concentrations increased 1.9%, while TN and TP yields increased by 12.7%, and 10.2%, respectively as the area of the cropland increased. Stream discharge was unchanged. Moreover, TN yield increased as the percentage of land occupied by cornfields increased while TP yield increased as the percentage of land occupied by soybean increased, due to differences in crop management practices such as fertilization and tillage.

Cecil Charter had taught botany and biology in China and Antigua for five years, when in 1931 he was engaged to conduct a soil survey of the sugarcane-growing areas of Antigua. This was followed by similar surveys elsewhere in the Caribbean. In 1944, he joined the West African Cacao Research Institute in the Gold Coast (now Ghana) to carry out soil investigations in the forest zones of West Africa. In 1949 he moved to organise the soil survey unit in the Gold Coast Department of Agriculture, and, in 1951, to found and direct the new Soil and Land Use Survey Department. He rapidly built up a highly professional unit that produced many practical and useful reports of high quality. He based the surveys on ecological principles, selecting river basins as mapping regions. In the initial absence of qualified soil scientists, he subdivided the soil survey process and trained school leavers as technicians for separate tasks. Teams of these technicians examined soils, vegetation and land use at regular intervals on regularly-spaced traverses cut across the topography. Charter’s contributions to soil science included his recognition of non-residual tropical soils formed in material brought to the surface by soil fauna and treefall. Also, he differentiated between highly acidic upland Oxysols in high-rainfall areas, which he considered unsuitable for cocoa cultivation, and less acidic Ochrosols, which were more suitable. Based on farmers’ experience and his ecological background, he differentiated between forest, thicket and savannah soils within these groups. He strongly advocated genetic and contextual classification of tropical soils.

We investigated the genesis and local response of soils in mountain sites of the Sila Massif (Calabria, southern Italy), reforested ca. 60 years ago, and their relationships with geomorphic dynamics and forest stand structure. A multidisciplinary approach is proposed, focused on an often neglected soil profile scale and horizon-wise sampling strategy, and including pedological field observations, physical, chemical, mineralogical analyses, isotope geochemistry including fallout radionuclides (137Cs and 210Pbex), geomorphology, historical documentation of anthropogenic land cover changes, forestry and dendrometric measurements. Reforestation was carried out following extreme land degradation, which took place after forest clearance and field cultivation. Different tree species and soil preparation techniques were used according to site conditions. We focused on the main properties of selected soil profiles and the distribution of some radionuclides, in order to understand the effects of forest stands on hampering soil erosion and promoting novel soil formation, and to evaluate the potential hazard of natural gamma radiation. A comparison with soil profiles developed under naturally regenerated forest and field crops was achieved. The soil profiles in reforested sites showed a poor degree of development and a complex history of reworking processes alternated with soil-formation processes, in line with modern to historical radiocarbon dates increasing downprofile, the presence of buried horizons and 137Cs in the topsoils. Inventory changes obtained for 210Pbex and 137Cs highlight a process of soil stabilization occurred after reforestation, with more efficient effects under Calabrian pine than oak forest, whereas major geomorphic dynamics (erosion and accumulation) were triggered by forest coppicing, thinning and agricultural practices. Our data remark a positive response of the soil ecosystem to reforestation against erosion, trapping mobile material, stabilizing buried soils, promoting humus accumulation leading to new shallow topsoils, and the protective role of forests against anthropogenic and climatic-induced threats. Average values of the annual outdoor effective dose equivalents of gamma-emitting radionuclides calculated for all the soil horizons showed lower values than the population-weighted world’s average, with the exception of the soil profiles under forest stands developed on granite, exceeding this threshold. A deeper comprehension of soil genesis, geomorphic processes, land use and vegetation dynamics in vulnerable ecosystems such as mountain environments represents a fundamental basis for sustainable land management policies.

Prehistoric land use at the Guobei site and its relationship with the local environment are examined by applying OSL dating, micromorphological examination and geo-physical analysis. The majority of the OSL dates are of early to middle Holocene ages and are thus comparable to many OSL dates derived from other studies in the same region. According to the particle size analysis, silt-sized particles (2–60 μm) were predominant throughout the profiles examined. However, there are spatial and temporal variations of different size groups of particles throughout the profiles, which provide complementary information for the micromorphological interpretation. The total organic component of the samples examined through LOI is relatively high (all > 2%), with those of the overlying Holocene deposits higher than those of the underlying Malan loess by about 0.2%. Moreover, in all three profiles, the highest organic contents appear in the palaeosols, confirming that there was greater organic accumulation during soil formation periods. The groundmass of most slides collected from the early to middle Holocene horizons displays a very homogeneous pattern, while the abundance and distribution of different kinds of pedo-features, mainly including clay textural, calcitic, iron/Mn and crustal features, vary greatly temporally and spatially. These different lines of information demonstrate diversified pedo/sedimentary processes due to variations in micro-environmental conditions and cultural activities. We discuss the importance of a palaeo-ecological perspective, allowed by the geoarchaeological study, to an improved understanding of the relationship between loess, changing hydrology, prehistoric farming practice and land use, and long-term landscape change in the Chinese Loess area. This will thus contribute to a comparison on the dynamic relationship between loess and prehistoric farming in other regions of the world such as Europe and North America.

The aim of this paper is to assess the impacts of projected climate change on a Mediterranean catchment, and to analyze the effects of a suite of representative land use practices as an adaptation tool to reduce climate change-driven erosion and hydrologic extremes. Relevant climatic variables from the ERA-Interim global atmospheric reanalysis of the European Centre for Medium-Range Weather Forecasts (ECMWF) were downscaled for the study area, and perturbed with the anomalies of 23 global circulation models for three emission scenarios (B1, A1B and A2). Both a projected daily rainfall time series for the period 2010-2100, and a single precipitation event with a one-hundred year return period were used to assess the impact of climate change. The downscaled data were fed into a distributed hydro-sedimentary model (TETIS) with five land use configurations representative of future demographic tendencies, geographical characteristics and land management policies (e.g. European Union CAP). The projected changes showed a general decrease in runoff and sediment production by the end of the century regardless of land use configuration. Sediment production showed a positive relationship with an increase in agricultural land and a decrease in natural land under present day agricultural management. According to our simulations, some conservation practices in agriculture can effectively reduce net erosion while maintaining agricultural production. As such, they can play a critical role as an adaptation tool to reduce climate change impacts in the 21st century., This study was funded by the Spanish Ministry of Economy and Competitiveness through the research projects CLARIES (ref. CGL2011-29176) and PALEOMED (CGL2014-58127-C3-1-R).

Three pairs of small, fourth- to sixth-order catchments (approximately 5–80 km2), draining the margin of the Darjeeling Himalayas into the piedmont, were selected for a comparison of the land-use impact on the morphology and sedimentology of their stream channels. Each pair experienced similar annual rainfall and comprised similar metamorphic bedrock, steep topography, and brown soils; the members of each pair contrast with respect to their land-use structure as they comprise large forest cover (forest >90%) and a significant contribution of agricultural land with tea plantations (forest

Highlights • RUSLE application to assess impacts of the Mati devastating fire on soil erosion. • First RUSLE application in a Wildland Urban Interface/ WUI at a Mediterranean area. • Remote sensing data (Sentinel-2) were utilized to assess fire severity (NBR index) • Post-fire erosion rates are notably higher, especially within the WUI zone. • Realistic results attest that RUSLE can perform well at such diverse conditions., In recent years, forest fires have increased in terms of frequency, extent and intensity, especially in Mediterranean countries. Climate characteristics and anthropogenic disturbances lead forest environments to display high vulnerability to wildfires, with their sustainability being threatened by the loss of vegetation, changes on soil properties, and increased soil loss rates. Moreover, wildfires are a great threat to property and human life, especially in Wildland-Urban Interface (WUI) areas. In light of the impacts and trends mentioned above, this study aims to assess the impact of the Mati, Attika wildfire on soil erosion. The event caused 102 fatalities, inducing severe consequences to the local infrastructure network; economy; and natural resources. As such, the Revised Universal Soil Loss Equation (RUSLE) was implemented (pre-; post-fire) at the Rafina, Attika watershed encompassing the Mati WUI. Fire severity was evaluated based on the Normalized Burn Ratio (NBR). This index was developed utilizing innovative remotely sensed Earth Observation data (Sentinel-2). The high post-fire values indicate the fire's devastating effects on vegetation loss and soil erosion. A critical “update” was also made to the CORINE Land Cover (CLC) v. 2018, by introducing a new land use class namely “Urban Forest”, in order to distinguish the WUI configuration. Post-fire erosion rates are notably higher throughout the study area (4.53–5.98 t ha−1 y−1), and especially within the WUI zone (3.75–18.58 t ha−1 y−1), while newly developed and highly vulnerable cites now occupy the greater Mati area. Furthermore, archive satellite data (Landsat-5) revealed how the repeated (historical) wildfires have ultimately impacted vegetation recovery and erosional processes. To our knowledge this is the first time that RUSLE is used to simulate soil erosion at a WUI after a fire event, at least at a Mediterranean basin. The realistic results attest that the model can perform well at such diverse conditions, providing a solid basis for soil loss estimation and identification of high-risk erosion areas.

Tibetan subalpine meadows are being converted rapidly to cultivated lands because of the growing needs of food for humans and fodder for livestock. This land conversion could reduce the pools of C, N and P that are stored in the soil. Consequently, the assessment of the impact of land cultivation or fencing on soil nutrients and properties could improve sustainable grassland management. This study compared soil nutrients and properties of four land use types in a subalpine meadow: (1) natural pasture grazed traditionally by domestic yak and sheep; (2) fenced natural pasture which excluded grazing livestock; (3) land cultivated for oat fodder (oat land); and (4) land cultivated for barley grain (barley land). Soil measurements were done at three depth levels (0–10 cm; 10–20 cm; 20–30 cm) after three years of cultivation or fencing. Compared to the natural pasture, soil carbon and nitrogen parameters all decreased significantly in the barley land, were similar or increased in the fenced pasture and showed mixed but moderate changes in the oat land. Total phosphorus generally showed insignificant changes in all treatments. At the 0–10 cm soil layer, there was a gain in carbon in the fenced pasture (5.18 mg C·ha−1·yr−1), a loss in carbon in the barley land (7.50 mg C·ha−1·yr−1) and a slight loss in carbon in the oat land (0.88 mg C·ha−1·yr−1). Thus, cultivation for barley reduced soil nutrients substantially in the subalpine meadow, particularly in the surface soil layer, while cultivation for oats resulted in moderate changes. We concluded that land cultivation for oats and soil nutrient recovery by short-term fencing after cultivation are preferred alternatives of land use than cultivation for grain barley in the subalpine meadows of the northeast Tibetan plateau.

The Grain-for-Green program was implemented in China in 1999 to reduce soil erosion, increase biodiversity, conserve natural resources and improve the natural environment by modifying patterns of land use. The located field experiment about the influence of different land-use types (LUTs) on nutrient contents and changes in the soil profile or the degree of influence over time was conducted for many years in Liudaogou watershed. The contents of soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), available P (AP) and two inorganic N forms, ammonium-N (AN) and nitrate-N (NN), were determined in 0–200 cm soil profiles in five terraced and three sloped LUTs. The terraced LUTs were bare land (BAT), farmland (FAT), abandoned land (ABT), forage land (FOT, with alfalfa) and shrubland (SHT, with the peashrub Caragana korshinskii), and the sloped LUTs were farmland (FAS), abandoned land (ABS) and forage land (FOS). All of these LUTs were converted from traditional farmland except for FAT and FAS and they are carefully maintained for the last 50 years. SOM and TN contents were significantly higher after conversion from farmland to shrubland or grassland (15.6–34.9%) and decreased (51.5–77.1% for SOM in 0–40 cm, 49.7–72.1% for TN in 0–60 cm) with depth for all LUTs. TP and AN contents throughout the profiles were not significantly affected by land use, but NN was leached and accumulated in farmland only. AP content was highest throughout the profile in ABS when TP and AP contents were higher in sloped land than terraced land. SOM, TN and AN contents did not differ significantly for the same land-use patterns in the two topographies. SOM and TN contents in the surface soil increased with the length of recovery. Our observations demonstrated that the Grain-for-Green program has improved the nutrient contents and fertility of the soil and has increased SOM and TN stocks over time and that these effects were not limited to the topsoil. Abandoned land may be the optimal choice for nutrient sequestration in terraced and sloped land. Shrubland and artificial grassland are also recommended for increasing soil nutrient content in the area.

The natural abundance of δ15N in soils is a simple tool for understanding ecosystem nitrogen cycling. However, the main drivers for soil δ15N in different natural land use types are not clear enough. To investigate the main drivers for soil δ15N in different land uses, we measured δ15N in the top 10 cm of the soil along a precipitation gradient with various land uses on the Loess Plateau of China, which covers a total area of 620,000 km2 and is one of the most erodible area in the world, to determine effects of climatic, soil and vegetation factors on soil δ15N and the relationships between them using the partial least squares regression (PLSR) method. Soil δ15N ranged from 1‰ to 9‰ on the Loess Plateau with an average of 5.8‰ in forest lands, 5.6‰ in shrub lands, and 4.8‰ in grasslands. Calculated variable influence on projection by PLSR showed that both soil properties (including soil organic carbon content, total nitrogen content and soil texture) and mean annual precipitation influenced soil δ15N strongly. In addition, site elevation also influenced soil δ15N strongly in forest lands. The dominant controls of soil δ15N varied among three land use types on the Chinese Loess Plateau, and PLSR would be a reasonable tool to predict soil δ15N.

38 Pags.- 5 Figs.- 3 Tabls. The definitive version is available at: https://www.sciencedirect.com/science/journal/03418162, Patterns of erosion, transport and deposition of soil particles not only affect the distribution of mineral fraction of the soil but their organic components. The spatial variability of soil nutrients in Mediterranean mountain agroecosystems that combine complex land uses and abrupt topography is poorly documented despite emerging concerns on nutrients fate require understanding the potential impact of soil erosion on nutrients redistribution across landscapes. This study aims to assess at catchment scale the spatial patterns of soil organic and inorganic carbon (SOC, SIC), soil organic carbon fractions and total nitrogen (TN) in relation to land uses and soil redistribution. To this purpose we selected a well characterized endorheic catchment located in NE Spain where soil erosion and deposition rates derived from 137Cs measurements were previously documented and we mapped the distribution of cropland and rangeland areas. A grid of 100 × 100 m was established for collecting a total of 205 soil samples for nutrients and standard soil analyses. In both rangeland and cropland the patterns of SOC and TN stocks were clearly related to 137Cs inventories thus significantly lower nutrient stocks (SOC: 34.1 ± 18.6 Mg ha−1, TN: 2.9 ± 1.7 Mg ha−1) were found in erosional sites whereas higher stocks (SOC: 44.9 ± 24.2 Mg ha−1, TN: 3.9 ± 2.3 Mg ha−1) were recorded in depositional areas. In cropland the mean nutrients contents (SOC: 1.1 ± 0.8%, TN: 0.1 ± 0.1%) were significantly lower than in rangeland (SOC: 3.2 ± 2.1%, TN: 0.2 ± 0.1%). The highest C/N ratios (29) were found in rangeland, while in cropland they occurred in depositional areas with their values below 10 in the erosional sites. In turn, the SIC content (range 0.4 to 10.2%) was slightly lower at the depositional sites (4.9 ± 2.2%) but not significantly different from the erosional sites (5.1 ± 2.2%). Cultivated and steep slopes led to loss of soil and nutrients due to intense erosion processes also related to tillage and crop productivity. Our findings provide evidence that the combined effect of land use and soil redistribution exert an important control on the spatial distribution of nutrients, highlighting a significant decrease of SOC and TN stocks with increasing soil erosion in croplands. The information gained achieves a better understanding of soil nutrients dynamics and further knowledge for effective land management of mountain agroecosystems in the Mediterranean region., This research was funded by the project (CGL2014-52986-R) of the Spanish Ministry of Science, Innovation and Universities.

This paper investigates soil stratigraphy of lynchets in sloping lands in eastern Belgium, and rates of their development by comparison to tillage translocation by non-mechanised agriculture. In Belgium, detailed topographical surveys and augerings were carried out at three sites that were under cropland till 1900–1950. Rates and diffusion constants of current non-mechanised tillage erosion were monitored in Ethiopia using tracers, and by precise surveys of tillage steps of known ages. The lynchets in Belgium consist of colluvium that was removed at the upper border of previously farmed plots. Repeated tillage with animal drawn implements results in soil translocation fluxes to the lower plot borders in the order of 11 to 91 kg m − 1 year − 1 (for slope gradients between 0.03 and 0.35 m m − 1 ). The studied lynchets in eastern Belgium would have required cropping agriculture for a total of 217–585 years on steep, and 1037–1867 years on gentle slopes. The establishment of lynchets hence took place without any deliberate action of digging, but due to repeated tillage, even with simple implements, and water erosion. Calculated time spans of tillage indicate that some parts of the study area had already been under cultivation during the Gallo-Roman period, others since the Middle Ages.

Overland flow connectivity and runoff and sediment trap effectiveness are currently the cutting edge topics in soil erosion research. The effect of agricultural terraces, irrigation channels and trails on runoff and soil erosion modelling at catchment scale is still a remaining research question. In this study we run the index of connectivity of Borselli et al. (2008) and a modified version of the revised Morgan, Morgan and Finney (RMMF) model to predict the hydrological connectivity and the rates of soil erosion under four different scenarios of land uses and land abandonment. This goal is achieved by using geographic information systems (GIS) in the Estanque de Arriba catchment (74 ha; Spanish Pre-Pyrenees) where 83 soil samples were collected. The different maps of hydrological connectivity were used to create runoff and sediment trap effectiveness masks that were included in the assessment of the effective cumulative runoff. The results showed that the index of connectivity was very high in the irrigation channels and walls of the agricultural terraces for the past and current scenarios. The runoff and sediment connectivity of the catchment from the hillsides to the lake decreased with an increasing vegetation cover and a decreasing number of linear landscape elements. The connectivity decreased from the past to the current scenario and from the current to the future scenario with vegetation recovery in the abandoned fields. The vegetation factor appeared to be more important than the disappearance of the agricultural terraces and channels to explain the changes in the connectivity at catchment scale. Random changes in the IC values appeared between the current and the future scenario without vegetation recovery in some parts of the catchment and were related to the mathematical procedure of the model that combines the upslope and downslope components at each pixel. This information is of special relevance in areas disturbed by humans and those with complex topography. The average erosion rates ranged between 1.5 and 3.7 Mg ha–1 yr–1 for the different land use scenarios decreasing with the increase of the vegetation recovery in the abandoned fields. A significant percentage of the study area will suffer more erosion in the early stage of future land abandonment with an increasing volume of overland flow in the fields at the bottom of the catchment whereas soil erosion will decrease significantly after long-term land abandonment with vegetation recovery. Further research is proposed to better account the changes that happen in the soil and vegetation parameters at the early stages of land abandonment. The results of this study suggest that current active systems could be stabilized by trapping and retaining eroded sediment by increasing the vegetation cover and preserving the agricultural terraces., This research was financially supported by the project: “Soil erosion and carbon dynamic in Mediterranean agroecosystems: radioisotopic modelling at different spatial and temporal scales (MEDEROCAR, CGL2008-00831/BTE)” funded by the Spanish Ministry of Science and Innovation. This study was also conducted with cooperation from the EC-DG RTD-6th Framework Research Programme (sub-priority 1.1.6.3)-Research on Desertification- project DESIRE (037046): Desertification Mitigation and Remediation of land – a global approach for local solutions. M. López-Vicente would also like to acknowledge the Alfonso Martín Escudero Foundation for its postdoctoral fellowship for the year 2010 and to Mrs. Elena Calvo-Seas for her collaboration in the field surveys.

To investigate the factors controlling nitrate-nitrogen (NO_[3]^[-]-N) dynamics during snowmelt season and rainfall events, this study was conducted in three adjacent headwater stream watersheds with coupled land use and topography characteristics in eastern Hokkaido, Japan. The agriculture-dominated watershed (AW) had flat topography in agricultural area, the forest-dominated watershed (FW) was characterized by a steep slope in forest area, and the mixed agriculture-forested watershed (AFW) had flat topography in the agricultural area and steep topography in the forest area. Results showed that the timing of NO_[3]^[-]-N export is different between the forested and steep watershed FW and the agricultural and flat watershed AW. The NO_[3]^[-]-N export peaked before discharge peak with quick subsurface flow during snowmelt and rainfall events in the AW, while after discharge peak with slow subsurface flow in the FW. The difference in the timing of NO_[3]^[-]-N export is attributed to the subsurface flow which is regulated by the coupled characteristics of topography and land use. The fast release of NO_[3]^[-]-N in the FW was attributed to the "flushing mechanism", which was driven by the rapid response of the subsurface flow due to the macropores in the forest soil and the steep slope. The AW showed a consistent "prolonged flush" of NO_[3]^[-]-N, where NO_[3]^[-]-N concentrations peaked after the peak of discharge, which might be attributed to the slow occurrence of subsurface flow because of the flat slope and the low hydraulic conductivity of the pasture. In the AFW, the NO_[3]^[-]-N concentration peaked before the discharge peak during the snowmelt season but after the discharge peak during the rainfall events, indicating other factor such as the macropores related to the freeze/thaw cycles replaced of the coupled characteristics of topography and land use controlling the timing of NO[3]^[-]-N export in the mixed watershed.

35 Pags., 6 Tabls, 5 Figs. The definitive version is available at: http://www.sciencedirect.com/science/journal/03418162, Cultivation on mountain landscapes has been identified as a main factor triggering soil erosion. Patterns of erosion, transport and deposition of soil particles in agricultural landscapes appears to be closely linked to that of soil nutrients. In this work the redistribution of soilorganiccarbon and nitrogen and of soil particles is analysed in different geomorphic parts of mountain fields. A southern orientated hillslope was selected as representative of main land uses in mountain farmland of the Central Spanish Pyrenees. In the region, as much as 74% of its surface was abandoned in the last decades and as a result patterns of soil and nutrient losses in the fields were affected by both land abandonment and tillage. A set of cultivated and abandoned fields with different ages of land abandonment, slope gradients and lengths were selected to conduct this study. In each of the fields, total soil depth sampling was done in different parts of the slope to assess the pattern distribution of soilorganiccarbon (SOC) and nitrogen (SON). Other general soil properties analysed: pH, EC, carbonate content, grain size distribution and additional information derived from fallout caesium 137 provided supplementary information for better understanding the patterns of soil and nutrient redistribution. In the cultivated fields SOC and SON contents were higher and comparable to contents in the older abandoned fields, because the recovery of the natural vegetation after a long-term period of abandonment equalized the nutrient conditions in the cultivated fields that had regular additions of manure. In general SOC and SON percentages increased from the upper slope to the bottom slope of the fields with percentage increases ranging from 4 to 54% and from 1.5% to as much as 77%, respectively. Similarly, significant increases of SOC and SON inventories (45 and 49%, respectively) were registered at the bottom slopes of longer fields by comparison with lower increases (33 and 30%, respectively) in shorter and steeper fields. Soil deposition at the bottom slope as indicated by the 137Cs residuals was paralleled with increases in SOC and SON contents. Under the land use practices in the studied fields the bottom slope positions accumulate soil particles and act as sinks of soilcarbon and nitrogen in these mountain agricultural landscapes., This work was funded by the CICYT project MEDEROCAR (CGL2008-0831).

Due to rainfall variation and poor land cover, water erosion in the loess hilly area is severe and experiences high temporal fluctuations, which increase the difficulties of erosion quantification, prediction and control. In this study, 15 runoff plots were implemented in Dingxi, a typical loess hilly area of Gansu Province since 1986. Three typical years representing WY (wet year), NY (normal year) and DY (drought year) were firstly filtered based on the consecutive rainfall-erosion data and an aridity index. Then, water erosion dynamics involving five land uses (cropland, alfalfa, scrubland, woodland and grassland) in the three typical years were analyzed. The following results were found. Firstly, the most severe annual erosion rates did not appear in WY, but in DY. Moreover, the rates in DY were far higher than those in NY and WY. Secondly, although total rain depth and number of events were in the order of WY>NY>DY, mean maximal intensity of erosive rainfall however, was in the order of DY>NY>WY. This finding is important for erosion control. Namely, we cannot judge water erosion degree just from annual rainfall. More attention should be paid to the specific rainfall variables and distributions. Thirdly, different land uses played an important role with sea buckthorn reducing water erosion in contrast to spring wheat cultivated on steep slopes. Lastly, regardless of different drought-level years, only a few number of events with high intensities were responsible for the majority of annual soil and water loss. (C) 2010 Elsevier B.V. All rights reserved.

The final version is available at: http://www.sciencedirect.com/science/journal/03418162, In the Eastern Rif of N Morocco, soil conservation is seriously threatened by water erosion. Large areas of soil have reached an irreversible state of degradation. In this study, the 137Cs technique was used to quantify erosion rates and identify the main factors involved in the erosion process based on a representative catchment of the Eastern Rif. To estimate erosion rates in terms of the main factors affecting soil losses, samples were collected taking into account the lithology, slope and land use along six selected transects within the Boussouab catchment. The transects were representative of the main land uses and physiographic characteristics of that Rif sector. The reference inventory for the area was established at a stable, well preserved, matorral site (value of 4250 Bq m-2). All the sampling sites were eroded and 137Cs inventories varied widely (between 245 and 3670 Bq m-2). The effective soil losses were also highly variable (between 5.1 and 48.8 t ha-1 yr-1). Soil losses varied with land use. The lowest average values were on matorral and fallow land (10.5 and 15.2 t ha-1 yr-1, respectively) but much higher with alfa vegetation or cereal crops (31.6 and 27.3 t ha-1 yr-1, respectively). The highest erosion rate was on a badland transect at the more eroded part of the catchment, with rates exceeding 40 t ha-1 yr-1 and reaching a maximum of 48.8 t ha-1 yr-1.The average soil losses increased by more than 100 % when the slope increased from 10º (17.7 t ha-1 yr-1) to 25º (40. 8 t ha-1 yr-1). Similar results were obtained when comparing erosion rates in soils that were covered by matorral with respect to those under cultivation. Lithology was also a key factor affecting soil loss. Soils on marls were more erodible and the average erosion rates reached 29.36 t ha-1 yr-1, which was twice as high as soils on the glacis and old fluvial terraces (average rates of 14.98 t ha-1 yr-1 ). The radiometric approach was very useful to quantify erosion rates and to examine the pattern of soil movement. The analysis of main erosion factors can help to promote rational soil use and establish conservation strategies in the study area., This work was funded by the bilateral projects 2004MA-1005 and 18304-RM from the Agencia de Cooperación Interuniversitaria and the CICYT projects RADIERO (REN2002-02702/GLO) and REM (CGL2005-02009/BTE).

Understanding of the characteristics of soil organic matter (SOM) and soil nutrients at the field and catchment scale is important for refining agricultural management practices and for improving sustainable land use. In order to analyze on SOM and nutrient differences among different land use types and their relationships between land use, landscape position and slope aspect, 94 sampling sites including 7 land uses were selected along 6 transects in the Danangou catchment with an area of 3.5 km(2) on the Loess Plateau of China. Significant differences in SOM, total N (TN), available N (AN) and available P (AP) among these land uses were found.. Higher values in SOM, TN and AN were measured in soils from woodland and grassland, but lower values in the soils from fallow land and cropland. Compare SOM and TN with cropland, intercropping land had high contents. The adjusted R-2 values of regression models for SOM and nutrients with land use, landscape position and slope aspect ranged from 0.501 (SOM) to 0.134 (AP). A comparison between average predicted and measured values for SOM and each soil nutrient revealed that the predicted values in TP and AN for each land use, in SOM and TN except for fallow land and in AP except for intercropping land, shrub land and woodland, fell with in a 95% confidence interval about the measured values. The simplified predicted models of soil nutrients combined with the key value of SOM for soil quality can serve to improve agricultural practices and to provide useful information on sustainable land use. Improvement in SOM and nutrients would be expected from more C inputs including manure and crop residues and alternative cultivation practices such as developing intercropping system, building terrace for soil and water conservation, return the cropland with SOM content less than a key value of 0.44% to the grassland and woodland on the hilly areas similar to the Loess Plateau of China. At the same time, it is recommended that nitrogen fertilization addition could be decreased in the foot slope and increased on the upper slope. (C) 2003 Elsevier Science B.V. All rights reserved.

Soil moisture plays a critical role in both crop growth and vegetation restoration in semiarid environments. Its spatial and temporal variability results from topography, soils, vegetation and land uses. However, little knowledge exists about the effects of land use structure on soil moisture variability. In order to analyze soil moisture variations in relation to land use patterns, five land use structures and seven land use types were selected to monitor soil moisture. Soil moisture measurements were performed biweekly at 26 locations in a small catchment on the Loess Plateau of China from May to October 1998. The measurements were taken using a Theta-Probe at five depths of soil profile (0–5, 15–20, 25–30, 45–50 and 70–75 cm). These data were analyzed for soil moisture variations in space and time for seven land use types. Three peaks and three troughs of soil moisture variations during the growing season were found. The influence of shrubland on mean soil moisture within 0–70 cm was significantly different from that of cropland, orchard and intercropping land. Three types of soil moisture changes in profile were classified as increasing, decreasing and waving types. An analysis of the differences in soil moisture for five land use structures indicated that the influences of land use patterns on soil moisture were complex. This study provides an insight into the implications for hydrological modeling, runoff and erosion control in this area.

This article describes some of the results of a land evaluation within the framework of a research project carried out in a small catchment on the Loess Plateau in northern China, which has long been exposed to land degradation from erosion. The project aimed to identify an approach for land use planning, combining participatory (land users) planning, land evaluation and soil erosion modelling. The results from this study were intended to provide the biophysical properties of importance to be used together with results from participatory approach (PA) studies and soil erosion modelling to construct scenarios for a more sustainable use of land. Land properties, which were restricting for agricultural cropping, were defined and values of each property were matched with the requirements for cropping. By defining the spatial distribution of critical properties, they could be combined to achieve compound suitability classes in each land unit for the chosen land use. Information was gathered from measurements and data searches as well as from farmers, using PA methods. Properties for which data and other information were available and which were considered to be relevant for the study included climate, soil water content, slope aspect, soil water storage capacity, rooting environment, tillage constraints, slope gradient, infiltration capacity, soil nutrients and flooding hazard. Each of the properties were discussed in relation to their influence on land suitability, primarily for agricultural crops. Whatever management changes were carried out to improve the productivity and sustainability in the project catchment, restrictions for agricultural production were large. The major constraints were water availability, nutrient availability and erosion hazard. The properties chosen for further use in suitability evaluation and scenario analyses were those having a significant spatial variability in the catchment: soil type, slope gradient and slope aspect. The results from this study are applied in other articles this issue.

The Loess Plateau has been suffering from serious soil erosion for a long time, which originated in a population growth about 2000 years ago. After then, the rapid increase in human activity has led to more areas became used for grain production. Original vegetation has been destroyed and soil erosion has become more and more serious. Most research works indicate that the soil erosion on the Loess Plateau is mainly induced by irrational land use structure and low vegetation coverage. Controlling soil erosion is a significant factor in making a sustainable land use planning for the Loess Plateau. In this study, a procedure towards such a planning is presented, based on results from a research project in a small catchment on the Loess Plateau. A land suitability evaluation for rain-fed agriculture based on biophysical parameters, and a comparison between land suitability and current land use, were first carried out. Some potential land use scenarios, based on surveys on biophysical and socio-economic parameters in the catchment, and plans by the authorities, were proposed for further evaluation of their effects on soil erosion, economic feasibility and social acceptance. The scenarios were tested by (i) simulation modeling, to show the differences in erosion, and (ii) from studies on the influence of the scenarios on farmers' economy and their response. The results indicated that the following land use scenario was acceptable: all land with deep soil and slopes smaller than 15° is used for agriculture cropland, possibly combined with biological conservation measures, such as mulching combined with improved fallow, and all land with steeper slopes than 15° is used for other purposes (orchards and other cash trees, woodland, shrubland, grassland). A great reduction of on-farm income, however, would be induced on the short term by such a scenario. Local farmers will find it difficult to accept it unless financial support from external sources is available. On the long term, the scenario will be promising for both economic income improvement and soil erosion control since some production will be obtained from the conversion of cropland into orchards/cash trees (preferably on slopes 15–25°). Thus the land use modification should be carried out gradually. On the short term (5 year), it is suggested that cropland on steeper slopes than 25° is returned to woodland/shrubland/grassland while also fruit trees are planted on slopes 15–25°. Within 10 years, cropland with slopes steeper than 15° is suggested to be converted into orchard/woodland/shrubland/grassland.

Aerial photographs taken in 1976 and 1989 and a field survey in 1999 showed that land use in a 900-ha catchment in the southern part of the Ecuadorian Andes is highly dynamic. Over 23 years, ca. 83 ha of arable land was abandoned and ca. 70 ha was taken into agricultural production. Changes in land use were not spatially homogeneous. Parcels on unstable geologic formations and close to village centres were preferably set-aside. Land taken into cultivation was preferably located on gently sloping areas close to newly built sites and arterial roads. The area with bush vegetation increased by regeneration of natural vegetation on fields set-aside in the late 1970s and early 1980s. There was a complex interaction between water erosion and environmental change in the study area. Land taken into production was levelled for furrow irrigation: this led to a net reduction in the area susceptible to water erosion. However, one quarter of the area affected only by sheet and rill erosion 23 years ago has since become incised by deep gullies. This increase in gully density was related to inadequate construction and management of irrigation infrastructure, rather than to change in vegetation cover and/or soil erodibility caused by agricultural practices. This factor is often overlooked in studies of the effects of environmental change on geomorphologic processes. (C) 2002 Elsevier Science B.V. All rights reserved.

Vegetation cover is an important factor influencing the occurrence and movement of rainfall-triggered landslides, and changes to vegetation cover often result in modified landslide behaviour. However, it is difficult to relate the occurrence of landslides directly to variations in land use, especially in some European countries. In contrast, New Zealand provides a good opportunity to investigate geomorphic responses to anthropogenic land cover changes. Before European settlers first arrived in the 1840s, hilly regions were only marginally influenced by human activity. The Maoris, New Zealand's first settlers, lived largely on coastal plains or near lakes and rivers. They influenced general vegetation cover only through localized burning practices. In contrast, European settlers moved into the back country and converted extensive hill areas from native forest and bush to pasture. This reduced the strength of the regolith and rendered the slopes more susceptible to landslides. Pulses of natural sedimentation in the pre-European period have been related to volcanic activity, climatic variability, including changes in frequency of cyclonic storms and wind erosion and fluvial erosion following forest fires initiated either by volcanic eruptions or lightning strikes. Since European deforestation began, sediment production has largely been determined by landslide events. On unstable slopes, thousands of landslides were triggered by high-magnitude/low-frequency climatic events during storms with estimated return periods in excess of 50 years. In contrast, low-magnitude/high-frequency rainfall events have caused gully and channel erosion. Examples from different parts of New Zealand indicate changes in sediment-generating processes following land use modifications. After deforestation, landslides have contributed significantly to sediment sequences in depositional basins such as lakes, swamps, estuaries, coastal wetlands and the nearshore and offshore zones of continental platforms.

Inappropriate land use is one of the main reasons for soil erosion and nutrient loss in the hilly loess area. In the Yangjuangou catchment, which has typical hill and gully topography, the effects of land use changes on soil erosion and the distribution of soil nutrients and moisture were studied at the three spatial scales of total catchment, transect and land use type. Between 1984 and 1996, forest and grassland increased by 36% and 5%, respectively, and slope farmland decreased by 43%. The land use changes decreased annual soil erosion by 24%. The amounts of total N, total P, available N, available P and organic matter of surface soil (0–20 cm) and of moisture in the 0–70 cm soil suggest that a farmland/grassland/forest land use structure from hill foot to hill top has a better capacity for soil conservation and retention of nutrients than other land use structures. The contents of soil nutrients are in the order forest>grassland>slope farmland, and those of soil water are forest

Land uses and cultivation are important factors controlling SOC storage on the Loess Plateau. These factors may also affect the relative importance of different mechanisms for the stabilization of organic matter in the soil. Easily oxidizable organic carbon (EOC), aggregation and aggregate C fractions in the soil were measured under different land uses. Aggregates were fractionated using a wet-sieving procedure to obtain the distribution of water-stable aggregates. The fractions of aggregates, aggregate SOC and aggregate EOC in grassland and forestland were generally higher than those in farmland. Furthermore, because conventional cultivation destroyed aggregates, the dominant aggregate size fractions were 0.5mm for other land uses. Compared to the corresponding values in farmland, the mean weight diameter (MWD) in forestland and grassland increased by 808%–417%, and the stability ratio of water-stable aggregate (WSAR) increased by 920%–553%. Aggregate formation and its dominant size fraction were associated closely with its carbon fractions. SOC and EOC in farmland tended to be concentrated in smaller-sized aggregates, whereas SOC and EOC under other land uses tended to concentrate in larger-sized aggregates. EOC tended to concentrate in larger aggregates than SOC. The small fractions of the aggregates formed large fractions by combining with fresh organic matter. So converting slope farmland to forestland and grassland could improve the storage and quality of SOC, and the tendency of SOC transfer.