Showing papers by "Artemi Cerdà published in 2012"

Soil structural stability and erosion rates influenced by agricultural management practices in a semi‐arid Mediterranean agro‐ecosystem

Abstract: Unsuitable agricultural practices can cause loss in soil quality and erodibility to thus increase or trigger desertification under Mediterranean conditions. A field experiment was performed at the El Teularet-Sierra de Enguera Experimental Station (eastern Spain) to assess the influence during a 5-yr period of different agricultural practices on physical and chemical indicators of soil quality (total and water-soluble carbohydrates, glomalin-related soil proteins (GRSP), total organic carbon, aggregate stability (AS), vegetation cover and soil erosion). The management practices included residual herbicide use, ploughing, ploughing + oats, addition of oat straw mulch and a control (land abandonment). Adjacent soil under natural vegetation was used as a reference for local, high-quality soil and as a control for comparison with the agricultural soils under different management practices. Oat straw mulching led to higher levels of water-soluble carbohydrates, GRSP and AS and lower soil erosion rates, resulting in values similar to those in the soil under native vegetation. The lowest levels of carbohydrates and GRSP were for the plots that were treated with herbicide or were ploughed. The maintenance of and increases in stable aggregates promoted by the different agricultural management practices over the years were attributed to increases in labile organic fractions such as carbohydrates and to the GRSP content. The results demonstrate that land abandonment (control plot) or the use of a cover (plants or straw) contributes to increases in soil quality and reduces the risk of erosion. The research also shows that sustainable agricultural management allows soil to recover and that the use of straw mulching is the most effective management strategy.

Do conservative agriculture practices increase soil water repellency? A case study in citrus-cropped soils

Abstract: Water repellency is a property of soils that inhibits or delays infiltration. Long-term conservation practices as no-tillage, manure addition, application of herbicides may contribute to increase soil organic matter and, hence, soil water repellency. In this research, we have studied the effect of long-term addition of plant residues and organic manure, no-tillage and no chemical fertilization (MNT), annual addition of plant residues and no-tillage (NT), application of conventional herbicides and no-tillage (H), and conventional tillage (CT) on soil water repellency in Mediterranean calcareous citrus-cropped soils (Eastern Spain). Slight water repellency was observed in MNT soils, which may be attributed to the input of hydrophobic organic compounds as a consequence of the addition of plant residues and organic manure such has been demonstrated by the soil organic matter measurements. CT reduced the organic matter content and soils remained wettable. Subcritical water repellency (with water drop penetration times below 5 s) was observed in soils under NT and H treatments.

Comparative Kinetic Study of Carrier Type in a Moving Bed System Applied to Organic Matter Removal in Urban Wastewater Treatment

Abstract: In recent years, moving bed systems have been shown as an efficient technology in wastewater treatment and particularly in the treatment of urban effluents. This paper presents the results obtained for three different carriers in organic matter removal, analysing the influence of hydraulic retention time (HRT) and the filling ratio, as well as the kinetic constants of each carrier used. During the research, differences in the organic matter removal were observed under different conditions studied as a result of physical and geometrical characteristics of each carrier and their hydraulic behaviour. Two of the three carriers studied in this research had similar yields compared to the third carrier that presented lower rates of organic matter removal and lower kinetic constants than the other two. Carriers 1 and 2 obtained removal rates of organic matter in the form of soluble chemical oxygen demand (sCOD) above 50% for intermediate and higher filling ratios with HRTs of 15, 10 and 15 h, respectively. The maximum values obtained for carrier 1, 2 and 3 were 56.97%, 58.92% and 46.13%, respectively, under 15 h of HRT and 50% of filling ratio. The kinetic constants obtained by respirometry showed a similar trend to the values obtained from sCOD removal.

Efectos de los incendios forestales en la vegetación y el suelo en la cuenca mediterránea: revisión bibliográfica

Abstract: A review of fire effects on vegetation and soil in the Mediterranean basin. Mediterranean ecosystems are prone to forest fires and its recurrence played an important role in the evolution of these ecosystems. In addition, fires were more frequent after humans started controlling

Fire in Protected Areas - the Effect of Protection and Importance of Fire Management

Abstract: Fires are important but socially and economically unwanted disturbances of the ecosystems. They cannot be considered as a problem, they are global phenomena. Protected areas are created to protect biodiversity, and strict protection is often applied, forgetting that fire had shaped that that we aim to protect. This harsh protection is producing important changes in the protected habitats and is increasing their vulnerability to destructive wildfires. Thus, it is of major interest to incorporate fire management in the protected areas plan, including the (re)use of prescribed fire and traditional burning in order to reintroduce fire regimens, fundamental to the landscape sustainability. This incorporation represents an enormous step in the habitats sustainability. Policies should be more focused on fire prevention than on its suppression. DOI: http://dx.doi.org/10.5755/j01.erem.59.1.856

A review of fire effects on vegetation and soil in the mediterranean basin

Abstract: The topic of wildfire is a major research focus in the Mediterranean area. It was twenty years ago when was held a seminar titled «El papel del fuego en los ecosistemas mediterraneos» by Manuel costa in the «Universidad Internacional Menendez Pelayo» de Valencia with the attendance of prestigious scientists. Now wildfire and its management remain a major socio-economic issue and fire research keeps on progressing and clarifying important questions. The aim of this review is to summarise the key outputs from research carried out over the last 20 years on the effects of wildfire in the ecosystem of the Mediterranean basin with a particular focus on fire effects on vegetation, soil and hydrological processes. Fire has played a significant role in Earth processes for over 400 millions of years. Its occurrence influenced the composition of gases in the atmosphere, climate, weathering rates, erosion and deposition processes and acted as an ecological agent in ecosystem evolution. The composition and distribution of ecosystems are not only shaped by the climate but also by fire recurrence. In ecological terms, fire acts as a huge herbivore consuming biomass and affecting the world’s biome distribution. The Mediterranean environment is one of world’s key fire prone ecosystems. Its climate is characterised by hot, dry summers, providing ideal fuel conditions for combustion. Lightning and volcanic eruptions were the most common ignition sources before the humans existed, and fire was perhaps less frequent, but the areas affected larger due to a more homogeneous landscape distribution. Human activity has modified the natural fire recurrence by using it as a tool for clearing the forest for habitation, agri- and silviculture and hunting. The Neolithic agricultural revolution may have initiated the biggest change when fire was used to clear forests for agriculture and pastures. Such controlled use of fire has been in use in some form almost until the 1960’s in the Mediterranean basin. The rural population was dispersed, managing a mosaic-like landscape composed of crops, forest and pastures with low risk of extensive uncontrolled fire. Today’s Mediterranean landscape is the result of millennia of intensive human use and management.

Effects of fire on ash thickness in a Lithuanian grassland and short-term spatio-temporal changes

Abstract: Ministerio de Ciencia e Innovacion de Espana-CGL2007-28764-E / BTE, CGL2008-01632-E / BTE y CGL2009-06861- E / BTE

Relación entre la escala espacial y escorrentía superficial en una pequeña cuenca hidrográfica semiárida ante condiciones contrastadas de humedad del suelo (Extremadura, Suroeste de España)

Abstract: The present paper studies the hydrological processes (surface runoff) at different spatial scales in the dehesa ecosystem: pedon scale with a rainfall simulator, slope scale with surface runoff measurements in open plots and, finally, catchment scale of order 1 and 2. The hydrological behaviour at the different levels is analized under two contrasting conditions: dry and humid environment. The results show that at the microplot and at the hillslope scale the dominating factors of runoff production are easier to explain than at the catchment scale, where heterogeneity increases, with discontinuous fluxes due to reinfiltration in the sediment-filled valley bottoms. The influence of soil moisture on the processes has been defined as well.