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Post-fire soil erosion mitigation at the scale of swales using forest logging residues at a reduced application rate
Prats, Sergio A. ; González-Pelayo, Óscar ; Silva, Flavio C. ; Bokhorst, Koen J. ; Baartman, Jantiene E.M. ; Keizer, Jan J. - \ 2019
Earth Surface Processes and Landforms 44 (2019)14. - ISSN 0197-9337 - p. 2837 - 2848.
effectiveness - erosion - mulch - organic matter - wildfire
Mulching with forest residues has proved to be highly effective in reducing post-fire soil losses at the plot scale. However, its effectiveness has not been quantified at the application rates that are typically used in operational post-fire land management (2–3 Mg ha-1 using straw), as well as at scales larger than 100 m2. The present study compared post-fire erosion rates for six convergent hillslopes or swales of 500 to 800 m2, three of which were left untreated while the other three were mulched immediately after the fire with shredded eucalypt bark at a rate of 2.4 Mg ha-1. Erosion rates were monitored at irregular intervals during the first three post-fire years, whilst ground cover was assessed yearly. Selected topsoil properties (0–2 cm) such as organic matter content and aggregate stability were determined at a single occasion – two years after the wildfire, for three micro-environments separately: bare soil, and under mulch/litter and vegetation. Soil losses on the untreated swales decreased with post-fire year from 2.2 to 0.4 and 0.11 Mg ha-1 yr-1 (respectively for the first, second and third post-fire years), while the mulched swales produced 84%, 77% and 38% less soil losses than the untreated swales. Soil losses also depended on slope aspect, with the north-facing swales producing less erosion than the west-facing ones. This could be linked to their significant differences in bare soil, vegetation and stone cover, or a combination thereof. The type of micro-environment also played a significant role in topsoil properties (stone content, bulk density, resistance to penetration/shear stress, porosity and organic matter content). The present results add to the increasing evidence that forest residues should be duly considered for operational post-fire land management. Forest residues were highly effective in reducing erosion from swales at application rates as low as the typical 2 Mg ha-1 of post-fire straw mulch.
From genes to ecosystems in microbiology : Modeling approaches and the importance of individuality
Kreft, Jan Ulrich ; Plugge, Caroline M. ; Prats, Clara ; Leveau, Johan H.J. ; Zhang, Weiwen ; Hellweger, Ferdi L. - \ 2017
Frontiers in Microbiology 8 (2017)NOV. - ISSN 1664-302X
Agent-based modeling - Gene-centric modeling - Heterogeneity - Individuality - Metabolic flux modeling - Microbial ecology - Single cell
Models are important tools in microbial ecology. They can be used to advance understanding by helping to interpret observations and test hypotheses, and to predict the effects of ecosystem management actions or a different climate. Over the past decades, biological knowledge and ecosystem observations have advanced to the molecular and in particular gene level. However, microbial ecology models have changed less and a current challenge is to make them utilize the knowledge and observations at the genetic level. We review published models that explicitly consider genes and make predictions at the population or ecosystem level. The models can be grouped into three general approaches, i.e., metabolic flux, gene-centric and agent-based. We describe and contrast these approaches by applying them to a hypothetical ecosystem and discuss their strengths and weaknesses. An important distinguishing feature is how variation between individual cells (individuality) is handled. In microbial ecosystems, individual heterogeneity is generated by a number of mechanisms including stochastic interactions of molecules (e.g., gene expression), stochastic and deterministic cell division asymmetry, small-scale environmental heterogeneity, and differential transport in a heterogeneous environment. This heterogeneity can then be amplified and transferred to other cell properties by several mechanisms, including nutrient uptake, metabolism and growth, cell cycle asynchronicity and the effects of age and damage. For example, stochastic gene expression may lead to heterogeneity in nutrient uptake enzyme levels, which in turn results in heterogeneity in intracellular nutrient levels. Individuality can have important ecological consequences, including division of labor, bet hedging, aging and sub-optimality. Understanding the importance of individuality and the mechanism(s) underlying it for the specific microbial system and question investigated is essential for selecting the optimal modeling strategy.
Effect of fire frequency on runoff, soil erosion, and loss of organic matter at the micro-plot scale in north-central Portugal
Hosseini, Mohammadreza ; Keizer, Jan Jacob ; Pelayo, Oscar Gonzalez ; Prats, Sergio Alegre ; Ritsema, Coen ; Geissen, Violette - \ 2016
Geoderma 269 (2016). - ISSN 0016-7061 - p. 126 - 137.
Fire repetition - Pine plantation - Post-fire erosion - Runoff
Wildfire is a natural phenomenon that is a common ecological factor in Mediterranean ecosystems. The increase in occurrence in recent decades has raised widespread concern about the impact of repeated wildfires on runoff and erosion, a topic that has not been widely studied. We addressed these concerns in an area of north-central Portugal by comparing runoff at the micro-plot scale and the associated transport of sediments and organic matter (OM) in unburnt, once burnt, and repeatedly burnt plantations of Maritime Pine. We selected nine sites following a large wildfire in September 2012 that affected roughly 3000 ha of the Viseu municipality. Three of the sites had not been burnt since 1975 and acted as controls, with covers of pine trees, shrubs, and annual vegetation; three sites had burnt only in 2012 and contained burnt pines but no shrubs or annual vegetation; and three degraded sites had suffered from three wildfires prior to 2012 and contained no vegetation. We established nine micro-plots (0.25 m2) at each site and collected runoff, eroded soil, and OM losses in tanks after each rain from October 2012 to September 2014. The repeated wildfires strongly increased the runoff coefficient and the risk of downstream flooding after heavy rains. OM losses were nearly half the volume of the eroded soil in the degraded sites due to the transport of ash in the runoff. Runoff and soil losses occurred not only after erosive rainstorms following a fire but also after a subsequent period of drought. Soil cover, rain intensity, and soil moisture were key factors in the amount of runoff and erosion. The insights provided by this study can contribute to pre- and post-fire activities and management in protect areas and can thus improve post-fire recovery.
Strategies to prevent forest fires and techniques to reverse degradation processes in burned areas
Ferreira, António José Dinis ; Alegre, Sérgio Prats ; Coelho, Celeste Oliveira Alves ; Shakesby, Rick A. ; Páscoa, Fernando M. ; Ferreira, Carla Sofia Santos ; Keizer, Jan Jacob ; Ritsema, Coen - \ 2015
Catena 128 (2015). - ISSN 0341-8162 - p. 224 - 237.
Forest fires - Prevention approaches and techniques - Recover strategies and techniques - Soil degradation
Forest fires are probably the more deleterious event in forest and range areas in the Mediterranean nowadays. Despite the significant area burned every year, little has been done to develop strategies and techniques for soil and water conservation in burned areas, despite the major impacts on soil erosion and hydrological processes. The main problem is the fast speed at which soil and water degradation occur right after the fire, in response to the first autumn rainfall events. This limits the opportunities to mitigate the deleterious impacts. This paper presents several ex-ante strategies and techniques, such as the forest planning, prescribed fire and preventive forestry, and several ex-post techniques, such as mulching, seeding, hillslope barriers, creating infiltration opportunities, channel treatments and ecosystem restoration. To be effective and implementable, techniques must be in place as soon as possible, if possible before the first rainfall events, since a significant exportation of ash and soil losses occur after the first rainfall events from burned systems. The ex-post techniques can mitigate the degradation processes, but due to the fast implementation and to the associated costs, should be implemented in key points within the burned area, driven by the knowledge on how hydrological and erosion processes work in burned areas. The objective is to attain the most cost-effective strategies and techniques that might include the integration of several techniques at various scales, to reduce the output of water, sediments and nutrients, and therefore the degradation of local ecosystems.
Mighty small: Observing and modeling individual microbes becomes big science
Kreft, J.U. ; Plugge, C.M. ; Grimm, V. ; Prats, C. ; Leveau, J.H.J. ; Banitz, T. ; Baines, S. ; Clark, J. ; Ros, A. ; Klapper, I. ; Topping, C.J. ; Field, A.J. ; Schuler, A. ; Litchman, E. ; Hellweger, F.L. - \ 2013
Proceedings of the National Academy of Sciences of the United States of America 110 (2013)45. - ISSN 0027-8424 - p. 18027 - 18028.
Progress in microbiology has always been driven by technological advances, ever since Antonie van Leeuwenhoek discovered bacteria by making an improved compound microscope. However, until very recently we have not been able to identify microbes and record their mostly invisible activities, such as nutrient consumption or toxin production on the level of the single cell, not even in the laboratory. This is now changing with the rapid rise of exciting new technologies for single-cell microbiology (1, 2), which enable microbiologists to do what plant and animal ecologists have been doing for a long time: observe who does what, when, where, and next to whom. Single cells taken from the environment can be identified and even their genomes sequenced. Ex situ, their size, elemental, and biochemical composition, as well as other characteristics can be measured with high-throughput and cells sorted accordingly. Even better, individual microbes can be observed in situ with a range of novel microscopic and spectroscopic methods, enabling localization, identification, or functional characterization of cells in a natural sample, combined with detecting uptake of labeled compounds. Alternatively, they can be placed into fabricated microfluidic environments, where they can be positioned, exposed to stimuli, monitored, and their interactions controlled “in microfluido.” By introducing genetically engineered reporter cells into a fabricated landscape or a microcosm taken from nature, their reproductive success or activity can be followed, or their sensing of their local environment recorded.
|Connectivity and thresholds in water and sediment transport in burned areas, Portugal
Ferreira, A.J.D. ; Coelho, C.O.A. ; Shakesby, R.A. ; Boulet, A.K. ; Prats, S.A. ; Stoof, C.R. ; Keizer, J.J. - \ 2008
|Mesures a les zones agrícoles amb finalitats de conservació del medi ambient, especialment el sòl i l'aigua.
Boerboom, J.H.A. - \ 1990
In: Jornades d'Estudi Sobre Les Zones de Muntanya, J. Ainud de Lasarte, J. Ganyet, R. Majoral, Ll. Prats (eds.). Dept. Cultura Generalitad Catalunya, Barcelona - p. 233 - 240.