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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.
Developing generalized parameters for post-fire erosion risk assessment using the revised Morgan-Morgan-Finney model : A test for north-central Portuguese pine stands
Hosseini, Mohammadreza ; Nunes, João Pedro ; Pelayo, Oscar González ; Keizer, Jan Jacob ; Ritsema, Coen ; Geissen, Violette - \ 2018
Catena 165 (2018). - ISSN 0341-8162 - p. 358 - 368.
Management - Morgan-Morgan-Finney model - Post-fire erosion - Repeated wildfires - Surface runoff
Models can be useful for predicting the hydrological impacts of natural phenomenon such as wildfires and to help implement effective post-fire land management options. In this research, the revised Morgan–Morgan–Finney (MMF) model was used to simulate runoff and soil erosion in recently burned maritime pine plantations with contrasting fire regimes, in a wet Mediterranean region of north-central Portugal. The MMF model was adapted for burnt areas by implementing seasonal changes in model parameters in order to accommodate seasonal patterns in runoff and soil erosion, attributed to changes in soil water repellency and vegetation recovery. The model was then evaluated by applying it for a total of 18 experimental micro-plots (0.25 m2) at 9 once burned and 9 four times burned slopes, using both previously published and newly calibrated parameters, with observed data used to evaluate the robustness and wider applicability of each parameterization. The prediction of erosion was more accurate than that of runoff, with an overall Nash-Sutcliffe efficiency of 0.54. Slope angle and the soils' effective hydrological depth (which depends on vegetation and/or crop cover) were found to be the main parameters improving model outcomes, and different parameters were needed to differentiate between the two contrasting fire regimes. This case study showed that most existing benchmark parameters can be used to apply MMF in burned pine forest areas with moderate severity fires to support post-fire management, but indicated that further efforts should focus on mapping soil depth and vegetation cover to improve these assessments.
The short-term effectiveness of surfactant seed coating and mulching treatment in reducing post-fire runoff and erosion
Hosseini, Mohammadreza ; Pelayo, Oscar Gonzalez ; Vasques, Ana ; Ritsema, Coen ; Geissen, Violette ; Keizer, Jan Jacob - \ 2017
Geoderma 307 (2017). - ISSN 0016-7061 - p. 231 - 237.
Effects of fire occurrence and recurrence on nitrogen and phosphorus losses by overland flow in maritime pine plantations in north-central Portugal
Hosseini, Mohammadreza ; Geissen, Violette ; González-Pelayo, Oscar ; Serpa, Dalila ; Machado, Ana Isabel ; Ritsema, Coen ; Keizer, Jan Jacob - \ 2017
Geoderma 289 (2017). - ISSN 0016-7061 - p. 97 - 106.
Wildfires have increased in Portugal in the recent decades, raising concerns about the long-term negative effects of fire recurrence on the environment. We studied the impacts of recurrent fires on the nitrogen (N) and phosphorus (P) content of mineral soil in the first year after a fire. Total nitrogen (TN) and phosphorus (TP) losses by runoff were also evaluated within the two years after a fire. Nine sites in a maritime pine forest were selected following a large wildfire in September 2012 that affected roughly 3000 ha of the Viseu municipality. Three sites had been burnt four times in the past 40 years (4 ×), three sites had been burnt once in September 2012 (1 ×), and three control sites had not been burnt (0 ×). Runoff was collected in 9 micro-plots (0.25 m2) at each site after rain events from September 2012 to September 2014. Soil N and P content were significantly higher in both burnt sites relatively to the control sites. Nitrogen as well as phosphorus losses via runoff were significantly higher at the 4 × burnt sites than at both the 1 × burnt and unburnt sites. Nutrient loss was particularly high after heavy rains. Vegetation and litter cover played an important role in reducing runoff and the associated N and P transport at the 4 × burnt sites, since a decrease in both variables was observed with the increase in vegetation cover after fire.
Fire-induced pine woodland to shrubland transitions in Southern Europe may promote shifts in soil fertility
Garcia Mayor, Angeles ; Valdecantos, A. ; Vallejo, V.R. ; Keizer, J.J. ; Bloem, J. ; Baeza, J. ; González-Pelayo, O. ; Machado, A.I. ; Ruiter, P.C. de - \ 2016
Science of the Total Environment 573 (2016). - ISSN 0048-9697 - p. 1232 - 1241.
Early warning indicators - Fire frequency - Mediterranean region - Microsite - Mineral soil - Pinus spp. woodlands - Soil quality - Sudden shift
Since the mid of the last century, fire recurrence has increased in the Iberian Peninsula and in the overall Mediterranean basin due to changes in land use and climate. The warmer and drier climate projected for this region will further increase the risk of wildfire occurrence and recurrence. Although the impact of wildfires on soil nutrient content in this region has been extensively studied, still few works have assessed this impact on the basis of fire recurrence. This study assesses the changes in soil organic C and nutrient status of mineral soils in two Southern European areas, Várzea (Northern Portugal) and Valencia (Eastern Spain), affected by different levels of fire recurrence and where short fire intervals have promoted a transition from pine woodlands to shrublands. At the short-term ( 5. years), a decline in overall soil fertility with fire recurrence was also observed, with a drop between pine woodlands (one fire) and shrublands (two and three fires), particularly in the soil microsites between shrubs. Our results suggest that the current trend of increasing fire recurrence in Southern Europe may result in losses or alterations of soil organic matter, particularly when fire promotes a transition from pine woodland to shrubland. The results also point to labile organic matter fractions in the intershrub spaces as potential early warning indicators for shifts in soil fertility in response to fire recurrence.
The use of barley straw residues to avoid high erosion and runoff rates on persimmon plantations in Eastern Spain under low frequency-high magnitude simulated rainfall events
Cerda, A. ; Gonzalez-Pelayo, O. ; Gimelnez-Morera, A. ; Jordan, A. ; Pereira, P. ; Novara, A. ; Brevik, E.C. ; Prosdocimi, M. ; Mahmoodabadi, M. ; Keesstra, S.D. ; Garcia Orenes, F. ; Ritsema, C.J. - \ 2016
Soil Research 54 (2016)2. - ISSN 1838-675X - p. 154 - 165.
Soil and water losses due to agricultural mismanagement are high and non-sustainable in many orchards. An experiment was setup using rainfall simulation experiments at 78 mm h-1 over one hour on 20 paired plots of 2 m2 (bare and straw covered) in new persimmon plantations in Eastern Spain. The effects of a straw cover on the control of soil and water losses was assessed. An addition of 60% straw cover (75 g m-2) resulted in delayed ponding and runoff generation and as a consequence reduced water losses from 60 to 13% of the total rainfall. The straw cover reduced raindrop impact and as a consequence sediment detachment from 1,014 to 47 g per plot in one hour. The erosion rate was reduced from 5.1 to 0.2 Mg ha-1 h-1. The straw mulch was found to be extremely efficient in reducing soil erosion rates.
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.
|The role of vegetation patches and antecedent soil moisture conditions in runoff and erosion connectivity in a 4-times burnt pine stand.
Regensburg, Taco ; Pelayo, Oscar Gonzalez ; Martins, M. ; Hosseini, M.R. ; Keesstra, S.D. ; Keizer, Jan Jacob - \ 2015
- 870 p.
As part of the EU-FP7 project CASCADE, which addresses tipping-points in land degradation of Mediterranean
ecosystems, the degradation drivers of repeated wildfires and post-fire drought spell are being studied in maritime
pine stands in north-central Portugal. Preliminary results indicated that overland flow and sediment losses were
markedly higher at 4–times burnt sites than at one-time burnt sites and, at the same time, that they were markedly
higher at recently burnt than long-unburnt sites. These results, however, concerned micro-plots where post-fire
recovery was mainly due to seeders and, as a consequence, rather reduced during the study period of the first two
years following the wildfire (“inter-patches”). In the framework of COST Action ES1306 (Connecting European
Connectivity Research), the present follow-up study aimed at assessing how the overland flow and erosion generated
at such inter-patches would be “handled” by downslope vegetation patches and, in particular, patches where
the main shrub species in the study area, Pterospartum tridentatum, had re-sprouted. More specifically, this study
wanted to assess: (i) how the sink function of these vegetation patches was influenced by potential flow length or
the length of the upslope inter-patch; and (ii) how it varied through time and, in particular, with antecedent soil
moisture content. The study site is a south-west facing slope in an area that had burnt, with moderate severity, in
early September 2012 and three more times before that since 1975 (as of when burnt area maps are available).
By the time of the 2012-fire, it was covered by a sparse maritime pine stand that was roughly 7-years old. During
October 2014, the study site was instrumented with a total of 12 bounded runoff plots, equally divided over the
three slope sections (upper, middle and lower). At each slope section, four types of plots were laid out using square
plots of 50 cm x 50 cm as basic building blocks. They were: (i) single inter-patch (50 cm x 50 cm); (ii) double interpatch
(50 cm x 100 cm); (iii) vegetation patch plus single upslope inter-patch (50 cm x 100 cm); (iv) vegetation
patch plus double upslope inter-patch (50 cm x 150 cm). This experimental design was envisaged to address the
following hypotheses: (i) runoff and erosion connectivity increase with increasing length of up-slope inter-patches;
(ii) vegetation patches act as effective sinks of run-on and transported sediments from upslope inter-patches; (iii)
the sink function of the vegetation patches is related to the influence of the shrubs on antecedent soil moisture conditions.
The latter hypothesis is tested by means of replicate but unbounded plots next to the above-mentioned 150
cm-long bounded, being instrumented with EC-5 soil moisture sensors to automatically record topsoil moisture
contents in a vegetation patch and upslope inter-patches. The very first results are pointing towards a confirmation
of the first two of the above-mentioned hypotheses.