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Fernandez C.,Research Center Forestal Lourizan | Vega J.A.,Research Center Forestal Lourizan
Ecological Engineering | Year: 2014

Slope stabilization treatments like mulching are frequently used to reduce runoff and erosion following high severity wildfires, but they may also affect native vegetation recovery or facilitate exotic species invasion. However, the effectiveness of many treatment options has not been well established, in particular, the use of wood-based mulches.In this study we assessed the efficacy of different methods of reducing soil erosion and the effects on vegetation recovery after a severe wildfire in Galicia (NW Spain). We compared the following treatments: straw mulch (2.0Mgha-1), bark strands mulch (3.5Mgha-1) and control (untreated). The straw mulch provided an initial ground cover of 70% and the bark strands mulch, 57%.During the first year after wildfire the mean sediment yield in the control plots was 5.4Mgha-1. In this period, the mean sediment yields in the treated plots were significantly lower than in the control plots (0.7Mgha-1 in the bark strands mulched plots and 0.5Mgha-1 in the straw-mulched plots). The bark strands mulch decayed very rapidly, so that six months after its application the mean cover had decreased to about 27%. Straw mulch persisted longer, and the mean cover was more than 40% at the end of the first year after fire.Soil erosion decreased sharply during the second year after wildfire with low and similar erosion yields in all cases.Straw mulching favoured vegetation cover recovery. Mulching did not have a significant effect on seedling emergence. Vegetation regrowth was very rapid and the total vegetation cover was about 70% at the end of the study.Mulching did not affect species composition, and there was also no evidence of the presence of any exotic species.The results indicate the feasibility of mulching with straw to reduce soil erosion after fire. The efficacy of bark strands mulch in controlling soil erosion losses during the first year after fire was probably due to the fact that most rainfall occurred when the cover provided by the mulch was maximal (i.e. before it decayed). This may indicate a limitation for soil protection the first year after fire when the erosion risk is highest. © 2013 Elsevier B.V.

Fernandez C.,Research Center Forestal Lourizan | Vega J.A.,Research Center Forestal Lourizan
Forest Ecology and Management | Year: 2016

Mulching is frequently used to reduce runoff and erosion following high-severity wildfires. In commercial forest stands, post-fire salvage logging is common practice, although it can lead to increased erosion losses in recently burned areas. Field research concerning the effects of post-fire salvage logging on sediment production is limited and the effects of clearcutting in areas previously treated by mulching are not known. In this study, 36 experimental plots were established in three experimental sites affected by crown fires that caused moderate-high soil burn severity in the summer of 2013. Immediately after the fire, bark strands mulch was applied in 18 of the plots. Salvage logging took place at the end of the first winter following fire. Post logging treatments were: mulching + salvage logging, no mulching + salvage logging and no mulching + no logging. The objectives of the study were to determine whether mulching mitigates soil erosion caused by fire and salvage logging and also to assess the possible effects of wildfire and salvage logging, with and without mulching, on vegetation recovery. During the six month period lapsed between the wildfire and salvage logging, precipitation was higher than the annual mean in the area, and the average soil loss in the untreated burned soils was 18.5 Mg ha-1. In that period, mulching significantly reduced soil loss (84%). In the 18-month period following salvage logging and in the absence of mulch, there was no increase in erosion due to logging (8.7 Mg ha-1) compared with the unlogged treatment (7.0 Mg ha-1) whereas mulching reduced significantly soil losses even after logging (2.3 Mg ha-1). Neither mulching nor salvage logging had any detrimental effects on the regeneration of natural vegetation. Our results showed that the mulching just after a fire can substantially reduce the subsequent erosion due to post-fire salvage logging without any significant adverse effects on vegetative regrowth. In addition, leaving the standing burned trees seemed not to be a feasible management option to reduce post-fire erosion and enhance vegetation recovery in those kind of stands. © 2016 Elsevier B.V.

Fernandez C.,Research Center Forestal Lourizan | Vega J.A.,Research Center Forestal Lourizan
Ecological Engineering | Year: 2016

Erosion barriers have traditionally been used in Europe by land managers to reduce runoff and erosion after high severity wildfires. However, field research investigating the effectiveness of this treatment is scarce in Europe. Previous research in the US and Europe has demonstrated that application of straw mulch at a rate of 2Mgha-1 effectively reduced post-fire sediment yields. For logistic and economic reasons, it would be useful to know whether a small reduction (25%) in the amount of straw mulch applied would significantly reduce the effectiveness of the treatment. In this study, we compared the effectiveness of a low rate of straw mulching (1.5Mgha-1) and of erosion barriers in reducing soil erosion during the first three years after a wildfire in Galicia (NW Spain). Twelve experimental plots (80m2) were established along a hillslope burned at high severity. During the three years of study, the accumulated soil loss in the untreated burned soils was 77.9Mgha-1. Mulching and erosion barriers both reduced soil loss (by respectively 38% and 26%). In all cases, soil erosion losses were high during the first two years after fire, which is an unusual response in the area. Maximum concentrated precipitation (rainfall >20mm accumulated in two consecutive days) and the Wischmeier's rainfall erosivity factor were the variables most strongly associated with soil loss during the study period. Although erosion barriers and mulch cover both reduced soil loss, relative to the untreated control, the effectiveness of these measures was low after the high-severity wildfire in an area affected by high rainfall. The lack of effect of vegetation cover on soil loss highlights the need for emergency measures to be implemented immediately after fire to protect the soil from erosion. © 2015 Elsevier B.V..

Vega J.,Research Center Forestal Lourizan | Jimenez E.,Research Center Forestal Lourizan | Vega D.,University of Vigo | Ortiz L.,University of Vigo | Perez J.R.,Research Center Forestal Lourizan
Forest Ecology and Management | Year: 2011

Maritime pine (. Pinus pinaster Ait.) is the tree species most affected by wildfire in the Iberian Peninsula. Prediction of the probability of fire-injured tree mortality is critical for management of burned areas, evaluation of the ecological and economic impact of wildfire and prescribed fire planning and application. Pine bark beetles (Scolytidae) frequently attack burned maritime pine stands and cause extensive post-fire mortality throughout the Iberian Peninsula. In the present study, maritime pine trees were monitored for three years following 14 wildfires in four ecotypes in Spain (11 fires in Galicia (Galician ecotype - NW Spain), one fire in Portillo (Meseta-Castellana ecotype - Central Spain), one fire in Rodenal (Rodenal ecotype - Central Spain), and one fire in Genalguacil (Sierra Bermeja ecotype - SW Spain)). Data on tree attributes, crown and bole injury, ground fire severity, . Ips sp. presence and tree survival were obtained by examining 3085 trees. Logistic regression models for predicting the probability of delayed maritime pine mortality were developed by use of generalized estimated equations (GEE). An ample range of response to fire damage in mortality was evident among the four ecotypes and different models were fitted for each. The most important variables for predicting tree mortality were total crown volume damaged, presence of . Ips sp. attack and cambium kill rating. The results highlight the extensive presence of . Ips sp. in burned maritime pine forests and its importance in tree mortality process, the ample range of response of . P. pinaster, in terms of post-fire mortality, as well as the need to develop site specific mortality models for the different ecotypes of this species following fire. © 2010 Elsevier B.V.

Fernandez C.,Research Center Forestal Lourizan | Vega J.A.,Research Center Forestal Lourizan | Fonturbel T.,Research Center Forestal Lourizan
Acta Oecologica | Year: 2013

Prescribed burning is commonly used to reduce the risk of severe wildfire. However, further information about the associated environmental effects is required to help forest managers select the most appropriate treatment. To address this question, we evaluated if fire severity during spring prescribed burning significantly affects the resprouting ability of two common shrub species in shrubland under a Mediterranean climate in NW Spain. Fire behaviour and temperatures were recorded in tagged individuals of Erica australis and Pterospartum tridentatum during prescribed burning. The number and length of resprouted shoots were measured three times (6, 12 and 18 months) after the prescribed burning. The influence of a series of fire severity indicators on some plant resprouting vigour parameters was tested by canonical correlation analysis. Six months and one year after prescribed burning, soil burn severity (measured by the absolute reduction in depth of the organic soil layer, maximum temperatures in the organic soil layer and the mineral soil surface during burning and the post-fire depth of the organic soil layer) reduced the resprouting vigour of E. australis and P. tridentatum. In contrast, direct measurements of fire effects on plants (minimum branch diameter, duration of temperatures above 300 °C in the shrub crown and fireline intensity) did not affect the post-fire plant vigour.Soil burn severity during spring prescribed burning significantly affected the short-term resprouting vigour in a mixed heathland in Galicia. The lack of effects eighteen months after prescribed burning indicates the high resilience of these species and illustrates the need to conciliate fire prevention and conservation goals. © 2013 Elsevier Masson SAS.

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