Showing papers in "Land Degradation & Development in 2014"
TL;DR: In this article, the impact of various management practices on soil loss in vineyards was evaluated in small vineyards located in southwestern Slovakia in the Vrable viticultural district, using the levelling method.
Abstract: Vineyards represent one of the most erosion-prone types of cultivated land. Because of this, cultivation practices are very important in reducing the soil erosion risk in vineyard regions. The aim of this paper was to assess the impact of various management practices on soil loss in vineyards. Effects of tillage, hoeing, rotavating and grass cover were evaluated in small vineyards located in southwestern Slovakia in the Vrable viticultural district. Erosion and deposition rates were estimated using the levelling method. This method is based on an evaluation of variability of the soil surface against vineyard poles measured between the year of pole insertion and the year of measurement. On the basis of the measured data, a WATEM/SEDEM distributed soil erosion model was calibrated, and the total soil loss from the vineyards under different management conditions was estimated. The model shows rather good performance in modelling soil erosion, but at the same time, it shows lower reliability in modelling soil deposition. Downslope tilled vineyards were the most eroded; the erosion in rotavated vineyards is somewhat reduced. The most protective tillage system is hoeing. Considerably lower soil loss was estimated with the use of vegetation cover between vine rows, which is in accordance with agro-environmental schemes supporting use of grass cover as an erosion prevention measure in vineyards. Copyright © 2012 John Wiley & Sons, Ltd.
213 citations
TL;DR: In this article, the effects of soil bunds on runoff, losses of soil and nutrients, and crop yield are rarely documented in the Central Highlands of Ethiopia, and a field experiment was set up consisting of three treatments: (i) barley-cultivated land protected with graded soil bund (Sb); (ii) fallow land (F); and (iii) barley grown land without soil bund(Bc).
Abstract: The effects of soil bunds on runoff, losses of soil and nutrients, and crop yield are rarely documented in the Central Highlands of Ethiopia. A field experiment was set up consisting of three treatments: (i) barley-cultivated land protected with graded soil bunds (Sb); (ii) fallow land (F); and (iii) barley-cultivated land without soil bund (Bc). For 3?years (2007–2009), the effect of soil bunds on runoff, losses of soil and nutrients, and crop productivity was studied. Daily runoff and soil and nutrient losses were measured for each treatment using standard procedures while barley yield was recorded from the cultivated plots. The results showed that Sb brought about significant reduction in runoff and soil losses. Plots with Sb reduced the average annual runoff by 28?per cent and the average annual soil loss by 47?per cent. Consequently, Sb reduced losses of soil nutrients and organic carbon. However, the absolute losses were still high. This implies the need for supplementing Sb with biological and agronomic land management measures to further control soil erosion. Despite these positive impacts on soil quality, Sb do not increase crop yield. Calculated on a per-hectare basis, Sb even reduce crop yield by about 7?per cent as compared with control plots, which is entirely explained by the reduction of the cultivable area by 8·6?per cent due to the soil bunds. Suitable measures are needed to compensate the yield losses caused by the construction of soil bunds, which would convince farmers to construct these land management measures that have long-term beneficial effects on erosion control.
206 citations
TL;DR: In this paper, an 18-year long-term field experiment involving pearl millet-cluster bean-castor sequence was conducted on an Entisol in western India to examine the effects of chemical fertilizers and manuring on carbon pools in relation to crop productivity and C sequestration.
Abstract: Soil organic carbon (SOC) pools are important for maintaining soil productivity and reducing the net CO2 loading of the atmosphere. An 18-year old long-term field experiment involving pearl millet-cluster bean-castor sequence was conducted on an Entisol in western India to examine the effects of chemical fertilizers and manuring on carbon pools in relation to crop productivity and C sequestration. The data showed that even the addition of 33.5 Mg ha−1 C inputs through crop residues as well as farm yard manure could not compensate the SOC depletion by oxidation and resulted in the net loss of 4.4 Mg C ha−1 in 18 years. The loss of SOC stock in the control was 12 Mg C ha−1. Conjunctive use of chemical fertilizers along with farm yard manure produced higher agronomic yields and reduced the rate of SOC depletion. The higher average seed yields of pearl millet (809 kg ha−1), cluster bean (576), and castor (827) over six cropping seasons were obtained through integrated use of fertilizers and manure. For every Mg increase in profile SOC stock, there was an overall increase of 0.46 Mg of crop yield, comprising increase in individual yield of pearl millet (0.17 Mg ha−1 y−1 Mg−1 SOC), cluster bean (0.14) and castor (0.15). The magnitude of SOC build up was proportional to the C inputs. Carbon pools were significantly correlated with SOC, which increased with application of organic amendments. Threshold C input of 3.3 Mg C ha−1 y−1 was needed to maintain the SOC stock even at the low antecedent level. Copyright © 2011 John Wiley & Sons, Ltd.
185 citations
TL;DR: The impacts of land use and climate change on runoff in the Yarlung Zangbo River basin, China were investigated by Zhang et al. as mentioned in this paper, who found that afforestation leads to increased runoff in dry seasons, whereas climate change clearly affected runoff within regions that experienced precipitation.
Abstract: Impacts of land use and climate change on runoff were investigated by studying the runoff in the Yarlung Zangbo River basin, China. Trends in precipitation, mean air temperature, and runoff were analysed by non-parametric Mann-Kendall tests. Land-use changes were examined with land-use transition matrix and geographic information system tools. Land-use and climate changes showed several characteristics, including increased reforestation, decreased grassland, retreat of glaciers and increased desertification. Human activity caused great impact, especially within densely populated regions and cities. Reforestation and degradation of grasslands were more frequent than deforestation and cultivation of grasslands. Annual mean air temperature, precipitation and runoff showed increasing trends between 1974 and 2000. The impacts of land use and climate change on runoff had different effects depending on region and season. In the season of freezing, climate change clearly affected runoff within regions that experienced precipitation. Altered evapotranspiration accounted for about 80 per cent of runoff changes, whereas land-use changes appear to have had greatest impact on runoff changes within regions that have inconsistent relationships between runoff and climate change. It was demonstrated that afforestation leads to increased runoff in dry seasons. It was estimated that glacier snow melt has caused annual runoff to increase at least 6 center dot 0mm/10yr, 2 center dot 1mm/10yr and 1 center dot 7mm/10yr in Regions 1, 3 and 4, respectively, whereas evapotranspiration caused annual runoff to decrease at least 7 center dot 4mm/10yr in Region 2. Copyright (c) 2012 John Wiley & Sons, Ltd.
169 citations
TL;DR: Investigation of impacts of grazing (intensity) and bush encroachment on herbaceous species and rangeland conditions in Borana, southern Ethiopia finds low to intermediate grazing levels may promote and conserve key forage species in savanna grazing lands.
Abstract: Grazing intensity and bush encroachment are disturbance factors that may alter the floristic composition of herbaceous species. This paper investigates impacts of grazing (intensity) and bush encroachment on herbaceous species and rangeland conditions in Borana, southern Ethiopia. Herbaceous species richness and the abundance of each species were greater in the light- and moderate-grazed areas than heavy-grazed sampling plots. Similarly, herbaceous species richness was highest at an intermediate level of biomass and seems to decline as biomass increases. Among a total of 40 herbaceous species recorded, 20 per cent were tolerant of grazing, whereas the remaining 80 per cent were highly susceptible to heavy grazing. In both encroached and non-encroached sampling plots, species richness varied from three to six species 0·25 m−2. Overall, herbaceous species richness and abundance, in relation to grazing gradient, might disclose a better picture of the effect of grazing on individual herbaceous species. As species richness seems to decline under heavy grazing intensity, low to intermediate grazing levels may promote and conserve key forage species in savanna grazing lands. Copyright © 2012 John Wiley & Sons, Ltd.
149 citations
TL;DR: In this paper, the effects of land use on soil moisture variations in the semi-arid Chinese Loess Plateau were examined as part of the ‘Grain for Green’ programme.
Abstract: Knowledge of the effects of land use on soil moisture variations is necessary to improve land and agricultural water management in the semi-arid Chinese Loess Plateau However, previous studies are insufficient to guide management practice in this area and improvement is needed to help with the development of the ‘Grain for Green’ programme As part of the ‘Grain for Green’ programme, we examined the effects of five land uses (fallow, grassland, cropland, 3-year and 8-year jujube orchards) on soil water variations in a small catchment on the Loess Plateau Soil moisture at 0–160 cm depth was monitored approximately weekly at 47 sites from 17 August to 19 October 2009 and from 4 April to 27 September 2010 using a portable time domain reflectometer Results indicated that mean soil water profiles in different land uses varied with time, land use induced spatial variations of soil water but exerted negligible influence on soil water temporal patterns, and soil water content was of the greatest spatial variability with moderate means (approximately 20 per cent) Furthermore, the relationship between standard deviation and mean water content was dependent on soil depth, although it was negligibly affected by land use Profile soil water for five land uses was different in various seasons, precipitation infiltration depth exhibited a positive correlation with precipitation, and the whole profile soil moisture (0–160 cm) was complemented following a 93·5-mm rainfall event The findings presented here provide helpful information for land and agricultural water management in this area Copyright © 2011 John Wiley & Sons, Ltd
143 citations
TL;DR: In this article, the authors investigate the main factors that influence smallholders' adoption decision of soil conservation measures in the Gedeb watershed and find that farmers need adequate cash to invest in soil conservation and are more encouraged to implement soil conservation when they have larger areas of cropland.
Abstract: The aim of this study was to investigate the main factors that influence smallholders' adoption decision of soil conservation measures in the Gedeb watershed. Data from 498 household heads who live in the three districts of the watershed were analysed using the binary logistic regression model. We find that farmers need adequate cash to invest in soil conservation measures. Moreover, farmers would be more encouraged to implement soil conservation measures when they have larger areas of cropland. We explore the possibility that when farmers presume that they have fertile land, they exploit their land more. This hints at the need for extension advice about the benefit of sustainable use of farmers' cropland so that they can maintain their land and pass it on to the future generation. Farmers' awareness about the benefit of land management practices and recognition of the problem erosion is causing on their crop land are central to their decision to adopt soil conservation measures. Furthermore, to adopt these measures, farmers have to be convinced about the effectiveness of these measures. Thus, awareness creation and demonstration of the effectiveness of these measures is essential. Because of the transboundary nature of the problem, policy makers in downstream countries that are suffering from the off-site impact (e.g. Sudan) would benefit from the information provided and support efforts in the implementation of soil conservation measures.
116 citations
TL;DR: In this paper, a study was conducted in a mixed vegetation cover watershed with forest, grass, cultivated and eroded lands in the degraded Shiwaliks of the lower Himalayas to assess land-use effects on profile organic carbon distribution and storage and quantify the SOC fractions in water-stable aggregates (WSA) and bulk soils.
Abstract: The proportional differences in soil organic carbon (SOC) and its fractions under different land uses are of significance for understanding the process of aggregation and soil carbon sequestration mechanisms. A study was conducted in a mixed vegetation cover watershed with forest, grass, cultivated and eroded lands in the degraded Shiwaliks of the lower Himalayas to assess land-use effects on profile SOC distribution and storage and to quantify the SOC fractions in water-stable aggregates (WSA) and bulk soils. The soil samples were collected from eroded, cultivated, forest and grassland soils for the analysis of SOC fractions and aggregate stability. The SOC in eroded surface soils was lower than in less disturbed grassland, cultivated and forest soils. The surface and subsurface soils of grassland and forest lands differentially contributed to the total profile carbon stock. The SOC stock in the 1.05-m soil profile was highest (83.5 Mg ha−1) under forest and lowest (55.6 Mg ha−1) in eroded lands. The SOC stock in the surface (0–15 cm) soil constituted 6.95, 27.6, 27 and 42.4 per cent of the total stock in the 1.05-m profile of eroded, cultivated, forest and grassland soils, respectively. The forest soils were found to sequester 22.4 Mg ha−1 more SOC than the cultivated soils as measured in the 1.05-m soil profiles. The differences in aggregate SOC content among the land uses were more conspicuous in bigger water-stable macro-aggregates (WSA > 2 mm) than in water-stable micro-aggregates (WSA < 0.25 mm). The SOC in micro-aggregates (WSA < 0.25 mm) was found to be less vulnerable to changes in land use. The hot water soluble and labile carbon fractions were higher in the bulk soils of grasslands than in the individual aggregates, whereas particulate organic carbon was higher in the aggregates than in bulk soils. Copyright © 2012 John Wiley & Sons, Ltd.
115 citations
TL;DR: In this article, paired-plot studies on how terrestrial organic carbon (SOC) stocks under native vegetation change after planting fast-growth Eucalyptus species in Brazil, where these plantations are becoming increasingly important.
Abstract: Proper assessment of environmental quality or degradation requires knowledge of how terrestrial C pools respond to land use change. Forest plantations offer a considerable potential to sequester C in aboveground biomass. However, their impact on initial levels of soil organic carbon (SOC) varies from strong losses to gains, possibly affecting C balances in afforestation or reforestation initiatives. We compiled paired-plot studies on how SOC stocks under native vegetation change after planting fast-growth Eucalyptus species in Brazil, where these plantations are becoming increasingly important. SOC changes for the 0–20 and 0–40 cm depths varied between −25 and 42 Mg ha−1, following a normal distribution centered near zero. After replacing native vegetation by Eucalyptus plantations, mean SOC changes were −1·5 and 0·3 Mg ha−1 for the 0–20 and 0–40 cm depths, respectively. These are very low figures in comparison to C stocks usually sequestered in aboveground biomass and were statistically nonsignificant as demonstrated by a t-test at p < 0·05. Similar low, nonsignificant SOC changes were estimated after data were stratified into first or second rotation cycles, soil texture and biome (savanna, rainforest or grassland). Although strong SOC losses or gains effectively occurred in some cases, their underpinning causes could not be generally identified in the present work and must be ascribed in a case basis, considering the full set of environmental and management conditions. We conclude that Eucalyptus spp. plantations in average have no net effect on SOC stocks in Brazil. Copyright © 2012 John Wiley & Sons, Ltd.
110 citations
TL;DR: In this paper, a study was carried out over 8884 km2 of the Tigray Highlands of northern Ethiopia using Landsat Multispectral Scanner and later Thematic Mapper imagery (1972, 1984/1986 and 2000), historical terrestrial photographs (1974-1975) and fieldwork (2008).
Abstract: The combined effects of erosive rains, steep slopes and human land use have caused severe land degradation in the Ethiopian Highlands for several thousand years, but since the 1970s, however, land rehabilitation programmes have been established to try to reverse deterioration. In order to characterize and quantify the transformations in the north Ethiopian Highlands, a study was carried out over 8884 km2 of the Tigray Highlands of northern Ethiopia. Using Landsat Multispectral Scanner and later Thematic Mapper imagery (1972, 1984/1986 and 2000), historical terrestrial photographs (1974–1975) and fieldwork (2008), we prepared land use and cover maps. For assessing the use of the historical terrestrial photographs, Landsat images from 1972 were classified using two different methods, namely conventional change detection (image differencing) and ground truthing (using the historical photographs of 1974–1975). Results show that the use of terrestrial photographs is promising, as the classification accuracy based on this method (Kappa coefficient 0·54) is better than the classification accuracy of the method based on image differencing (Kappa coefficient 0·46). Major land use and cover changes indicate the following: (1) a gradual but significant decline in bare ground (32 per cent in 1972 to 8 per cent in 2000); (2) a significant increase of bushland (25 to 43 per cent) and total forest area (including eucalypt plantations, 2·6 to 6·3 per cent); and (3) creation of numerous lakes and ponds. The dominant change trajectory (27 per cent of the study area) indicates a gradual or recent vegetation increase. These changes can be linked to the population growth and the introduction of land rehabilitation initiatives, complemented by growing awareness of land holders. Copyright © 2012 John Wiley & Sons, Ltd.
97 citations
TL;DR: The Mediterranean region covers about 854 million ha, but only 118 million (or 14 per cent) are suitable for agricultural production as discussed by the authors, with the remaining desert sands, shallow, rocky, saline, sodic soils and areas effectively sealed by urbanisation.
Abstract: The Mediterranean region covers about 854 million ha, but only 118 million (or 14 per cent) are suitable for agricultural production. In North Africa and the Middle East (MENA), agricultural land covers about 5 per cent; in Egypt and Algeria, it occupies less than 4 per cent and, in Libya, less than 2 per cent of the total national land area. Across the Mediterranean region land use divides between natural pastures/rangelands (ca. 15 per cent), forests and woodlands (ca. 8 per cent), with the ca. 63 per cent remaining desert sands, shallow, rocky, saline, sodic soils and areas effectively sealed by urbanisation. Land degradation is a severe problem in most Mediterranean countries. Estimates for the period 1961 to 2020 show that although the Mediterranean population is likely to more than double, ca. 8.3 million ha of agricultural land (7 per cent) may be lost as a result of continued urbanisation and land degradation. If these estimates are correct, agricultural land per capita would more than halve from ca. 0.48 ha (1961) to ca. 0.21 ha in 2020. Food security is likely to become increasingly problematic, especially in the MENA countries, which require a major reassessment of their agricultural development policy. Copyright © 2012 John Wiley & Sons, Ltd.
TL;DR: Wang et al. as mentioned in this paper investigated the severity of soil erosion according to the structure of the bench terrace and the ground cover conditions, and found that the planting of grass on the riser is the most important factor affecting runoff and sediment yield.
Abstract: The severity of soil erosion is considered to vary according to the structure of the bench terrace and the ground cover conditions. Erosion losses were investigated in a field experiment based on 20 m × 5 m erosion plots on a 21 per cent slope in Southern China. Five plots were established for the present study. Rainfall, runoff and sediment yield from plots were recorded for 5 years (2001–2005) and which five different types of terraces on sloping red soil were compared. The results show that the planting of grass on the riser is the most important factor affecting runoff and sediment yield, the next most important factor was the construction of a bund built on the edge of the terrace. Although the terrace bed slope (slope < 5 degrees) does not significantly affect the runoff, it does benefit the soil. A terrace combined with vegetation measures is effective in controlling runoff and soil erosion. Among various terraces, the level terrace (i.e. grass planted on the riser and bunds built on the edge of a bench terrace) is apparently the most beneficial for soil conservation purposes, indicating that this type is an excellent choice for conserving soil and water resources in sloping red soil in Southeastern China. Copyright © 2012 John Wiley & Sons, Ltd.
TL;DR: In this article, the effect of various organic amendments on select soil properties [soil organic carbon (SOC), pH, and electrical conductivity (EC)] over a 24-month period was investigated.
Abstract: Restoring the native vegetation is one of the most effective ways to control soil degradation in Mediterranean areas, especially in very degraded areas. In the initial months after afforestation, vegetation cover establishment and soil quality could be better sustained if the soil was amended with an external extra source of organic matter. The goal of this study was to test the effect of various organic amendments on select soil properties [soil organic carbon (SOC), pH, and electrical conductivity (EC)] over a 24-month period. Four amendments were applied in an experimental set of plots: straw mulching (SM), mulch with chipped branches of Aleppo Pine (Pinus halepensis L.; PM), sheep manure compost (SH), and sewage sludge (RU). Plots were afforested following the same spatial pattern, and amendments were mixed with the soil at the rate 10 Mg ha−1. Organic amendments helped maintain SOC over the initial 6 months after the afforestation. However, only the SM and PM treatments had increased SOC values after 24 months. Decreases in EC were found after the addition of SM, PM, and SH amendments. However, RU increased EC values 24 months after the afforestation. Variations in pH values were not sufficient to establish differences among the various treatments. Furthermore, the results show that forest soils with or without organic amendments responded similarly to the seasonal changes in Mediterranean conditions. Copyright © 2014 John Wiley & Sons, Ltd.
TL;DR: In this paper, the effect of crushed maize residues (particle size < 1 cm) and N supply on the evolution of soil biological properties and vegetal cover was investigated. And the results indicated that the addition of the crushed maize straw finely crushed + N fertilizers may be considered a good environmental strategy for recovery of degraded soils.
Abstract: Agriculture soils in the Mediterranean need restoration and rehabilitation after 10 millenia of use and abuse. Maize straw residues crushed at three sizes [ 10 cm (C3)] at 5 Mg ha−1 y−1 and with and without urea (150 kg N ha−1) were applied during a period of 3 years for the purpose of restoration of a Typic Xerofluvent located near Cordoba (Spain). The effect on the vegetal cover and biological properties (microbial biomass, soil respiration and enzymatic activities) were determined. The size of the crushed maize residues (particle size <1 cm) and N supply influenced in the evolution of soil biological properties and vegetal cover. The stimulation of microbial biomass, soil respiration, dehydrogenase, urease, β-glucosidase, phosphatase and arylsulphatase activities was higher in C1 + N-amended soils for 14·9%, 16·3%, 8·8%, 24·3%, 13·5%, 7·1% and 10·3%, respectively, compared with C2 + N and for 25·8%, 26·9%, 18·3%, 38·5%, 28·2%, 19·1% and 18·3%, respectively, compared with C3 + N. Vegetal cover from the C1 + N treatment was 11·4%, 17·8%, 29·4%, 37·6%, 44·9% and 75·1% greater than that in C2 + N, C3 + N, C1, C2, C3 and control soil. These results suggested that under dry climatic conditions, the application of crushed maize straw finely crushed + N fertilizers improved the soil biological properties and also favour the appearance of spontaneous vegetation, which will protect the soil and will contribute to its restoration. Consequently, the addition of the crushed maize straw finely crushed + N fertilizers may be considered a good environmental strategy for recovery of degraded soils. Copyright © 2014 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors evaluated existing field-based classifications of degraded alpine meadows in the Sanjiangyuan region, and examined the criteria on which these classifications are made, by using multivariate statistical approaches.
Abstract: Improving our understanding of abiotic and biotic thresholds that are transgressed during ecosystem degradation is vital for effective landscape-level restoration. Establishing logical and consistent typologies of degradation is an important first-step in this process. Areas of degraded alpine meadow in western China are referred to as Heitutan (or ‘black soil beach’) and cover vast areas. Previously, four classes of grassland degradation have been differentiated in this large area: non-degraded alpine meadow and moderate, severe and extreme Heitutan. We evaluated existing field-based classifications of Heitutan in the Sanjiangyuan region, and examined the criteria on which these classifications are made, by using multivariate statistical approaches. First, we asked whether existing qualitative classifications, based on vegetation cover and the abundance of impalatable plant species, adequately describe the nature of degradation at different locations. We then used a suite of vegetation and soil measures collected across 175 sites spanning a range of degradation conditions to develop a new quantitative assessment of degradation across the alpine meadows of the Qinghai-Tibetan Plateau. Hierarchical classification highlights two broad classes of degradation: non-degraded alpine meadow and degraded Heitutan. The non-degraded category effectively combines the non-degraded grassland and moderate classes, whereas the degraded Heitutan combines the severe and extreme Heitutan classes. Ordination analyses suggest that the four previously recognized classes of degradation intergrade. Of the 14 biophysical variables used to classify subsites on the basis of their degradation, bare ground area and vegetation cover are the two most useful predictors of grassland condition and associated ecological threshold conditions. Copyright © 2012 John Wiley & Sons, Ltd.
TL;DR: In this paper, the authors identified the most salient research needs in DLDD in drylands brought on by global drivers and identified research priorities given rise to these drivers, which are as follows: assessing impacts of rising prices on land degradation in mixed market and subsistence production contexts; assessing options and limits of agricultural modernisation on fragile lands; developing methods for assessing land-use trade-offs and mapping productive lands; modelling and participatory methods for monitoring and evaluating soil carbon sequestration; developing policy frameworks to regulate impacts of investment on the environment and local livelihoods; participatory modelling
Abstract: Recent rapid changes in global scale drivers of desertification, land degradation and drought (DLDD) have two important consequences for drylands. First, changes in these drivers, for example in food and energy prices, make improving interventions in drylands more urgent because of their potential impacts. Second, these changes introduce new knowledge gaps regarding both the potential impacts on social-ecological dryland systems and the design of options to take advantage of opportunities. This paper identifies the most salient research needs in DLDD in drylands brought on by global drivers. The question was addressed through an iterative stakeholder consultative forum. First, relevant global scale drivers were identified through a literature review and preliminary consultation. Next, stakeholders and experts were further consulted to identify research priorities given rise to by these drivers. Identified research priorities were as follows: (i) assessing impacts of rising prices on DLDD in mixed market and subsistence production contexts; (ii) assessing options and limits of agricultural modernisation on fragile lands; (iii) developing methods for assessing land-use trade-offs and mapping productive lands; (iv) modelling and participatory methods for monitoring and evaluating soil carbon sequestration; (v) developing policy frameworks to regulate impacts of investment on the environment and local livelihoods; (vi) participatory modelling for regional and local adaptation planning; and (vii) valuation of non-market land degradation outcomes including biodiversity loss. Concluding, we call for a forward-looking interdisciplinary drylands research agenda with an increased emphasis on governance to address these priorities. Copyright © 2013 John Wiley & Sons, Ltd.
TL;DR: In this paper, the effects of land cover conversion from temperate forest to avocado orchards on soil properties were determined in the Cupatitzio River sub-basin located in the Trans-Mexican Volcanic System and Balsas Depression in Mexico.
Abstract: In the present work, land cover and land use changes between 2003 and 2008 were assessed in the Cupatitzio River sub-basin located in the Trans-Mexican Volcanic System and Balsas Depression in Mexico. The effects of land cover conversion from temperate forest to avocado orchards on soil properties were determined. Land cover and land use databases were built for the years 1975, 2003, and 2008 using available cartographic information and interpretation of panchromatic SPOT images for the year 2008. Additionally, soil sampling was carried out in 16 representative sites in the higher parts of the sub-basin, where avocado plantation dynamics have caused important changes in areas covered by temperate forests. Results show that (i) temperate coniferous and tropical low deciduous forests were reduced at an annual rate of 0·9 per cent (1, 001 ha y−1) between 1975 and 2008; (ii) cropland areas expanded at an annual rate of 0·7 per cent between 1975 and 2008, representing a growth of 553 ha y−1; (iii) wet soil aggregate stability, mechanical resistance to penetration and nitrate (N-NO3) concentration in the topsoil layer of Andosols were significantly affected by land use conversion to avocado orchards. Other soil properties such as organic matter, interchangeable K, and available P showed degradation tendencies. These results suggest the importance of implementing strategies for mitigating the accelerated process of transformation and degradation of natural resources in the Cupatitzio River sub-basin. The implementation of programs for deforestation reduction should be a priority in the restoration strategy. Copyright © 2012 John Wiley & Sons, Ltd.
TL;DR: In this paper, the consequences of different cropping and tillage systems (undisturbed forest, coffee plantation, conventional, and no-tillage row cropping) for soil microbial indicators and sulfur mineralization after 24 years of cropping on an Oxisol (Typic Haplorthox) in an experimental area at Londrina, Brazil.
Abstract: Land use choices differentially affect soil physical and biological properties. Tillage choices in particular affect soil erosion, the retention of soil organic matter, and the biological activity that organic matter supports. The present study evaluated the consequences of different cropping and tillage systems (undisturbed forest, coffee plantation, conventional, and no-tillage row cropping) for soil microbial indicators and sulfur mineralization after 24 years of cropping on an Oxisol (Typic Haplorthox) in an experimental area at Londrina, Brazil. Soil samples were taken at 0–5, 5–10, and 10–20 cm depths and evaluated for microbial biomass P and S, S mineralization, and phosphatase and arylsulfatase activities. Land use affected microbial biomass P and S, and enzyme activity at all depths studied. The cultivated sites had lower values of microbial activity than the undisturbed forested site. Although the coffee site was not tilled and had high organic carbon content, there was low microbial activity, probably due to higher soil acidity and Al content. The estimates of pool stock for microbial P and annual P flux through the soil microbial biomass suggest that these pools are large enough to significantly affect plant nutrient availability. The greater microbial biomass and activity under forested and no-tillage sites may be attributed, at least partially, to higher organic matter content. The soil microbial variables examined proved to be strong indicators of soil sustainability. Copyright © 2013 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors measured the in situ soil CO2 flux from grassland, afforested land and reclaimed coalmine overburden dumps by using the automated soil CO 2 flux system (LICOR-8100® infrared gas analyzer, LICOR Inc., Lincoln, NE).
Abstract: The aim of this study was to measure the in situ soil CO2 flux from grassland, afforested land and reclaimed coalmine overburden dumps by using the automated soil CO2 flux system (LICOR-8100® infrared gas analyzer, LICOR Inc., Lincoln, NE). The highest soil CO2 flux was observed in natural grassland (11·16 µmol CO2 m−2s−1), whereas the flux was reduced by 38 and 59 per cent in mowed site and at 15-cm depth, respectively. The flux from afforested area was found 5·70 µmol CO2 m−2s−1, which is 50 per cent lower than natural grassland. In the reclaimed coalmine overburden dumps, the average flux under tree plantation was found to be lowest in winter and summer (0·89–1·12 µmol CO2 m−2s−1) and highest during late monsoon (3–3·5 µmol CO2 m−2s−1). During late monsoon, the moisture content was found to be higher (6–7·5 per cent), which leads to higher microbial activity and decomposition. In the same area under grass cover, soil CO2 flux was found to be higher (8·94 µmol CO2 m−2s−1) compared with tree plantation areas because of higher root respiration and microbial activity. The rate of CO2 flux was found to be determined predominantly by soil moisture and soil temperature. Our study indicates that the forest ecosystem plays a crucial role in combating global warming than grassland; however, to reduce CO2 flux from grassland, mowing is necessary. Copyright © 2012 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors evaluated soil erosion at both microsite and community scales in coexisting plant communities subject to sheep grazing in northeastern Patagonia and found that grass steppe is more resistant to land degradation than shrub steppes.
Abstract: Grazing has been identified as the main cause of land degradation in Patagonia. However, land degradation is highly variable among areas, even within the same paddock. This strongly suggests that different plant communities differ in their resistance to land degradation. In this study, we have evaluated soil erosion at both microsite and community scales in coexisting plant communities subject to sheep grazing in northeastern Patagonia. Three plant communities coexist in the area: two shrub steppes dominated by Chuquiraga avellanedae Lorentz and Nassauvia ulicina (Hook. f.) Macloskie, and a grass steppe dominated by Nassella tenuis (Phil.) Barkworth. At a community scale, our results indicate that shrub steppes generally experienced soil erosion, whereas the grass steppe commonly did not show signs of soil erosion/deposition. At a microsite scale, non-vegetated soil surface types and degraded mounds never accumulated sediments, regardless of plant community. In contrast, we found that in some sites, the intact mounds and grasses entrapped sediments, but in other sites, soil erosion prevailed. Our results highlight the fact that soil erosion measurements are scale dependent, because results at microsite and community scales often differ. When comparing among communities, grass steppe is more intensely grazed, but at the same time, it shows less evidence of past and present erosion. In contrast, the N. ulicina community showed a direct relationship between grazing and soil erosion. Finally, soil erosion was not related to grazing in the C. avellanedae community. Our results demonstrate that the grass steppe is more resistant to land degradation than shrub steppes. Copyright © 2014 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors assessed impacts of immigration on dry forests and options for improved management in a resettlement district in north-western Ethiopia and concluded that government programmes that opt for resettlement as a measure for poverty alleviation must also have mitigating measures to reducing negative impacts on the natural resource base.
Abstract: Deforestation in African dry forests is widespread and its drivers are complex and vary in space and time. In this paper, we assessed impacts of immigration on dry forests and options for improved management in a resettlement district in north-western Ethiopia. Key informants interviews, focus group discussions and household questionnaire survey were used to collect data. The results indicated that forests of the district are degrading in spatial coverage and quality. The most important drivers were land use change, excessive wood harvest, grazing pressure and forest fire following immigration. The continuous influx of people with different origins, cultures, religions and lengths of residence in the district underscores absence of social bonds for collective action to regulate access. This, coupled with weak formal regulatory system, market forces and policy incentives for farming, resulted in a near open access situation. Our findings confirm the negative relationships between migration and environment not necessarily because of the mere population number added through immigration but because of lack of regulatory frameworks (formal or informal) and poor social capital. Enforcing existing policy of farm size and putting institutional framework on the ground to regulate rate of immigration, extraction of forest products and to encourage tree planting to meet wood demand are suggested measures. We conclude that Government programmes that opt for resettlement as a measure for poverty alleviation must also have mitigating measures to reducing negative impacts on the natural resource base. Thus, the trade-off between environment and development must be carefully managed. Copyright © 2012 John Wiley & Sons, Ltd.
TL;DR: In this article, an ex-ante assessment of possible SLCP impacts was conducted with a focus on rural sustainability, taking the drought-prone region of Guyuan in Western China as an example.
Abstract: The goal of China's sloping land conversion programme (SLCP) is to combat soil erosion and to reduce rural poverty. An ex-ante assessment of possible SLCP impacts was conducted with a focus on rural sustainability, taking the drought-prone region of Guyuan in Western China as an example. The Framework for Participatory Impact Assessment (FoPIA) was used to conduct two complementary impact assessments, one assessing SLCP impacts at regional level and a second one assessing alternative forest management options, to explore possible trade-offs among the economic, social and environmental dimensions of sustainability. Regional stakeholders assessed the SLCP to be capable of reducing soil erosion but felt it negatively affected rural employment, and a further continuation of the Programme was advocated. Assessment of three forest management scenarios by scientists showed that an orientation towards energy forests is potentially beneficial to all three sustainability dimensions. Ecological forests had disproportionate positive impacts on environmental functions and adverse impact on the other two sustainability dimensions. Economic forests were assessed to serve primarily the economic and social sustainability dimensions, while environmental impacts were still tolerable. The FoPIA results were evaluated against the available literature on the SLCP. Overall, the assessment results appeared to be reasonable, but the results of the regional stakeholders appeared to be too optimistic compared with the more critical assessment of the scientists. The SLCP seems to have the potential to tackle soil erosion but requires integrated forest management to minimize the risk of water stress while contributing to economic and social benefits in Guyuan. Copyright (C) 2012 John Wiley & Sons, Ltd.
Abstract: Large areas in the Upper Tana river catchment, Kenya, have been over-exploited, resulting in soil erosion, nutrient depletion and loss of soil organic matter (SOM). This study focuses on sections of the catchment earmarked as being most promising for implementing Green Water Credits, an incentive mechanism to help farmers invest in land and soil management activities that affect all fresh water resources at source. Such management practices can also help restore SOM levels towards their natural level. Opportunities to increase soil organic carbon (SOC) stocks, for two broadly defined land use types (croplands and plantation crops, with moderate input levels), are calculated using a simple empirical model, using three scenarios for the proportion of suitable land that may be treated with these practices (low=40percent, medium=60percent, high=80percent). For the medium scenario, corresponding to implementation on ~348000ha in the basin, the eco-technologically possible SOC gains are estimated at 4� 8t o 9� 3 � 10 6 tonnes (Mg) CO2 over the next 20years. Assuming a conservative price of US$10 per tonne CO2-equivalent on the carbon offset market, this would correspond to ~US$48–93 million over a 20-year period of sustained green water management. This would imply a projected (potential) payment of some US$7–13ha � 1 to farmers annually; this sum would be in addition to incentives that are being put in place for implementing green water management practices and also in addition to the benefits that farmers would realize from the impact on production of these practices themselves. Copyright © 2012 John Wiley & Sons, Ltd.
TL;DR: In this article, the impact of the topographical position on soil properties was evaluated in an olive grove with traditional tillage, and three topographical positions: summit, backslope and toeslope were chosen for evaluation.
Abstract: The impact of the topographical position on soil properties was evaluated in an olive grove with traditional tillage. Three topographical positions: summit, backslope and toeslope were chosen for evaluation. The soil samples were taken from four soil sections of 0·25 m (0–1 m). The soil organic carbon (SOC) and N content increased along the downslope direction (5·5, 6·5 and 7·1 g C kg−1 and 0·3, 0·8 and 0·9 g N kg−1 in the surface layer in the summit, backslope and toeslope respectively) as well as SOC and N stocks, considering the two first soil sections. In addition, there was movement of the most erodible textural fraction (silt). However, the total SOC stock (refer to 1 m of depth) did not vary with respect to the topographical position, but the total N stock (refer to 1 m of depth) varied significantly. These increases were due to erosion processes that occur along the toposequence, leading to organic matter transfers from the summit to the toeslope. All the stratification ratios calculated were lower than 2, indicating the low quality of the soils. Therefore, alternative management techniques that avoid soil erosion must be considered in olive grove in order to increase the soil quality and fertility. Copyright © 2014 John Wiley & Sons, Ltd.
TL;DR: In this paper, the effects of compost application on soil carbon sequestration potential and carbon budget of a tropical sandy soil was studied, and the origin of soil organic carbon was identified by using stable carbon isotope.
Abstract: The effects of compost application on soil carbon sequestration potential and carbon budget of a tropical sandy soil was studied. Greenhouse gas emissions from soil surface and agricultural inputs (fertiliser and fossil fuel uses) were evaluated. The origin of soil organic carbon was identified by using stable carbon isotope. The CO2, CH4 and N2O emissions from soil were estimated in hill evergreen forest (NF) plot as reference, and in the corn cultivation plots with compost application rate at 30 Mg ha−1 y−1 (LC), and at 50 Mg ha−1 y−1 (HC). The total C emissions from soil surface were 8·54, 10·14 and 9·86 Mg C ha−1 y−1 for NF, HC and LC soils, respectively. Total N2O emissions from HC and LC plots (2·56 and 3·47 kg N2O ha−1 y−1) were significantly higher than from the NF plot (1·47 kg N2O ha−1 y−1). Total CO2 emissions from fuel uses of fertiliser, irrigation and machinery were about 10 per cent of total CO2 emissions. For soil carbon storage, since 1983, it has been increased significantly (12 Mg ha−1) under the application of 50 Mg ha−1 y−1 of compost but not with 30 Mg ha−1 y−1. The net C budget when balancing out carbon inputs and outputs from soil for NF, HC and LC soils were +3·24, −2·50 and +2·07 Mg C ha−1 y−1, respectively. Stable isotope of carbon (δ13C value) indicates that most of the increased soil carbon is derived from the compost inputs and/or corn biomass. Copyright © 2011 John Wiley & Sons, Ltd.
TL;DR: In this article, a comparative study of policies and strategies of Portuguese and Spanish (Comunitat Valenciana) cases is performed to assess the differences between them and identify their roles in forest fire prevention and in combating and mitigating impacts.
Abstract: Fires are the main driver of land degradation in forest areas in Mediterranean sub-humid regions and are likely to increase as a result of climate and other global changes. To prevent deleterious processes induced by fire, several policies and strategies have been implemented at national and regional scales. We perform a comparative study of policies and strategies of Portuguese and Spanish (Comunitat Valenciana) cases in order to assess the differences between them and identify their roles in forest fire prevention and in combating and mitigating impacts. To this end, we analyse the sustainability objectives stated in the legislation of each country to identify the strategies used to deal with forest fires and the extent to which they are integrated to achieve the sustainability objectives they pursue. The comparative analysis includes an assessment of sustainability, evaluated by the explicitness of the objectives, and identification of how the lines of action contribute to reach these objectives. We found different levels of complexity and that the adoption or rejection of some of the techniques is closely related to the tradition and the experience of local communities. This analysis highlights the importance of local characteristics and the stakeholders, involvement in designing effective strategies to reduce fire risk
TL;DR: In this paper, the effects of the dominant legume Acacia tortilis subsp. raddiana on soil properties were quantified in Bou-Hedma National Park.
Abstract: The objectives of this study, conducted in Bou-Hedma National Park, were to quantify the effects of the dominant legume Acacia tortilis subsp. raddiana on soil properties. Three sites with differing soil texture were studied; the first with a gravelly-sand texture, the second with a sandy-loam texture and the third with a loam texture. At each study site, two subhabitats were distinguished, under Acacia canopies (canopied soil) and open areas (uncanopied soil). Soil organic carbon, microbial biomass and microbial coefficient were found to be significantly greater in canopied soil, compared with uncanopied soil. The lower metabolic quotient under this legume indicated a higher carbon use efficiency of microorganisms in soil. The enzyme activities (dehydrogenase, phosphatase and β-glucosidase) expressing soil microbial activity were significantly higher under Acacia canopies. Therefore, A. raddiana planting can be considered an effective and applicable measure to restore vegetation and control desertification in arid regions.
On account of the variability of soil texture in the park, three sites were studied: gravelly-sand, sandy-loam and loam soils. The highest microbial density and activity were registrated in sandy-loam soil. Microbial biomass and activity increased gradually and significantly to a maximum at 20–30 cm and subsequently decreased at 30–50 cm. The results allow us to conclude that soil texture and soil depth can play an important role in the extent of soil properties. Copyright © 2011 John Wiley & Sons, Ltd.
TL;DR: This article investigated the adoption of bench terraces by applying a three-stage analysis using data from 301 households in the highlands of Rwanda and found that farmers' inability to maintain existing terraces may explain the reluctance to adopt new terraces.
Abstract: This paper investigates the adoption of bench terraces by applying a three-stage analysis using data from 301 households in the highlands of Rwanda. Ongoing adoption of bench terraces is ‘unpacked’ to consider both adopters willing to retain and increase the intensity of using terraces already constructed and new adopters willing to develop new bench terraces. Results suggest that farmers' inability to maintain existing terraces may explain the reluctance to adopt new terraces. The same inability explains why some of the terraces constructed earlier are not well maintained and fully used by farmers in northern and southern Rwanda. Policy actions aimed at improving farmer's capacity to invest in complementary inputs will sustain future generations of soil and water conservation measures in Rwanda. Copyright © 2012 John Wiley & Sons, Ltd.
TL;DR: In this article, the responses of microbial activity and nitrogen (N) transformations along an altitudinal gradient were examined, and the results showed that soil microbial biomass carbon (C) and basal respiration were significantly higher in MP and UP than in LP, whereas the microbial quotient was higher in LP and MP than in UP.
Abstract: A study was conducted to examine the responses of microbial activity and nitrogen (N) transformations along an altitudinal gradient. The gradient was divided into three parts. Three areas were sampled: upper part (UP): coniferous forest, corn field, and abandoned corn field; middle part (MP): tropical cloud forest, grassland, and corn field (COL); and lower part (LP): tropical deciduous forest and sugarcane. The results showed that soil microbial biomass carbon (C) and basal respiration were significantly higher in MP and UP than in LP, whereas the microbial quotient (Cmic/Corg) was higher in LP and MP than in UP. The metabolic quotient (qCO2) was similar among gradient parts evaluated. Net N mineralization, ammonification, and nitrification rates were higher in UP than MP and LP. We found that in UP, the forest conversion to cropland resulted in no significant differences in microbial activity and N transformation rates between land uses. In MP, microbial biomass C, ammonification, and net N mineralization rates decreased significantly with conversion to cropland, but Cmic/Corg and nitrification were higher in COL. Basal respiration and qCO2 were significantly lower in COL when compared with other land uses. In LP, lower microbial biomass C, Cmic/Corg, and nitrification rates but higher ammonification and net N mineralization rates were observed in tropical deciduous forest than in sugarcane. No significant differences in basal respiration and qCO2 were found between uses of LP. Clearly, then, soil organic C is not equally accessible to the microbial community along the gradient studied. Copyright © 2012 John Wiley & Sons, Ltd.