Soil water repellency after wildfires in the Blue Ridge Mountains, United States

2020 ◽  
Vol 29 (11) ◽  
pp. 1009 ◽  
Author(s):  
Jingjing Chen ◽  
Luke A. Pangle ◽  
John P. Gannon ◽  
Ryan D. Stewart

It is not well understood if wildfires induce soil water repellency in broadleaf deciduous forests, such as those endemic to the Blue Ridge Mountains of the eastern United States. In 2016, widespread wildfires provided an opportunity to study soil water repellency in this region. We selected sites in four locations with low to moderate burn severities, along with unburned controls. We estimated soil water repellency using water drop penetration time measurements from the surface (i.e. ash or organic) layer to ~5cm within the underlying mineral layer. Two months after the fires, water repellency was detected in all locations and was greater in more severely burned sites. One location had the greatest water repellency in surface ash (frequency of occurrence: 68–74%), whereas the other locations showed greatest repellency at the ash–mineral interface (40–96%). Unburned soils rarely showed repellency (0–18%). Burned soils also exhibited water repellency 1 year post fire. The study results suggest that combustion of non-resinous foliage within litter layers can cause water repellency in deciduous forests, meaning that this condition is not exclusive to coniferous and dryland forests. The duration of impact depends on fire severity, and may enhance overland flow and sediment transport in affected landscapes.

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 730 ◽  
Author(s):  
Moein Farahnak ◽  
Keiji Mitsuyasu ◽  
Kyoichi Otsuki ◽  
Kuniyoshi Shimizu ◽  
Atsushi Kume

Soil water repellency (SWR) is a cause of low water infiltration, overland flow and soil erosion in mountainous coniferous plantations in Japan. The factors determining SWR intensity were investigated in two coniferous plantations of Chamaecyparis obtusa (Siebold et Zucc.) Endl. and Cryptomeria japonica (L.f.) D. Don, using intact tree plots and cut tree plots on the same hillslope. The SWR of Ch. obtusa plots was stronger than that of Cr. japonica plots. SWR intensity decreased after tree cutting. There were no significant differences in SWR upslope and downslope of individual trees/stumps for both tree species, though areas downslope of individual Ch. obtusa trees had higher SWR intensity than those upslope. SWR intensity and soil aggregate stability were positively correlated in the Ch. obtusa intact tree plot (r = 0.88, p < 0.01), whereas in the cut tree plot, this correlation was weak with no significance (r = 0.29, p = 0.41). Soil aggregate size had a non-significant influence on SWR intensity. These findings suggest that SWR intensity was not related to the soil aggregate size, but SWR intensity seemed have a role in soil aggregation in the Ch. obtusa intact tree plot. Destruction of soil aggregates could occur after tree cutting because of physical disturbances or increased input of different types of organic matter from other vegetation into soil. The presence of Ch. obtusa introduces a source of SWR, although uncertainty remains about how water repellency is distributed around soil aggregates. The distribution pattern of soil water content and soil hydraulic conductivity around Cr. japonica was related to other factors such as the litter layer and non-water-repellant soil.


Soil Research ◽  
2005 ◽  
Vol 43 (3) ◽  
pp. 337 ◽  
Author(s):  
J. J. Keizer ◽  
C. O. A. Coelho ◽  
R. A. Shakesby ◽  
C. S. P. Domingues ◽  
M. C. Malvar ◽  
...  

Soil water repellency is now known to occur in diverse soils in various parts of the world. One of the possible adverse effects of soil water repellency is that it can reduce infiltration capacity and hence, on sloping terrain, enhance overland flow and soil erosion. The main aim of the present work is to assess the effects of soil water repellency on surface runoff production in the inner coastal dune areas of central Portugal. This was done for a pine and a eucalypt forest stand and, within each stand, for 2 slopes with contrasting aspect and somewhat different slope angles. Overland flow was measured for 4 pairs of unbounded plots of about 5 m2 at fortnightly intervals from February to October 2001. Over the same period, soil water repellency at and immediately below the soil surface was measured next to the plots at monthly intervals. The runoff–repellency relationship was also studied by carrying out rainfall simulation experiments on 0.24-m2 plots and associated repellency measurements. The effect of soil water repellency was most clearly demonstrated by statistically significant higher runoff coefficients under strong-to-extremely than under none-to-slightly hydrophobic conditions immediately below the soil surface. Such a difference in runoff over the measurement period was, however, restricted to 2 unbounded plots, both of which were located on the eucalypt slope with a southerly aspect and the greater slope angle. At the scale of these plots, the increase in runoff coefficient due to soil water repellency is moderate, when integrated over the entire period of strong–extremely repellent conditions, but can be quite substantial for individual 2-weekly periods. With respect to the observed differences in runoff between plots, be it plots on the same slope or not, it has proved difficult to distinguish the effect of soil water repellency from that of other factors likely to affect overland flow generation.


Geoderma ◽  
2021 ◽  
Vol 402 ◽  
pp. 115264
Author(s):  
Enoch V.S. Wong ◽  
Philip R. Ward ◽  
Daniel V. Murphy ◽  
Matthias Leopold ◽  
Louise Barton

2014 ◽  
Vol 65 (3) ◽  
pp. 360-368 ◽  
Author(s):  
I. Kim ◽  
R. R. Pullanagari ◽  
M. Deurer ◽  
R. Singh ◽  
K. Y. Huh ◽  
...  

2013 ◽  
Vol 22 (4) ◽  
pp. 515 ◽  
Author(s):  
Naama Tessler ◽  
Lea Wittenberg ◽  
Noam Greenbaum

Variations in forest fires regime affect: (1) the natural patterns of community structure and vegetation; (2) the physico-chemical properties of soils and consequently (3) runoff, erosion and sediment yield. In recent decades the Mediterranean ecosystem of Mount Carmel, north-western Israel, is subjected to an increasing number of forest fires, thus, the objectives of the study were to evaluate the long-term effects of single and recurrent fires on soil water repellency (WR) and organic matter (OM) content. Water repellency was studied by applying water drop penetration time (WDPT) tests at sites burnt by single-fire, two fires, three fires and unburnt control sites. Water repellency in the burnt sites was significantly lower than in the unburnt control sites, and the soil maintained its wettability for more than 2 decades, whereas after recurrent fires, the rehabilitation was more complicated and protracted. The OM content was significantly lower after recurrent than after a single fire, causing a clear proportional decrease in WR. The rehabilitation of WR to natural values is highly dependent on restoration of organic matter and revegetation. Recurrent fires may cause a delay in recovery and reduced productivity of the soil for a long period.


2014 ◽  
Vol 27 (5) ◽  
pp. 1413-1423 ◽  
Author(s):  
Nicasio T. Jiménez‐Morillo ◽  
José A. González‐Pérez ◽  
Antonio Jordán ◽  
Lorena M. Zavala ◽  
José María Rosa ◽  
...  

Author(s):  
Jim J. Miller ◽  
Mallory Owen ◽  
Ben Ellert ◽  
Xueming Yang ◽  
Craig F. Drury ◽  
...  

Soil water repellency (SWR) was measured for a 28 yr field study under irrigation on a clay loam Dark Brown soil in southern Alberta. The objectives were to study the effect of legume-cereal crop rotations, feedlot manure, and phosphorus (P) fertilizer application on soil hydrophobicity (SH) and soil water repellency index (RI) under irrigation. Mean SH and RI were similar (P > 0.05) for a legume-cereal and cereal rotation, and were unaffected by P fertilization. However, P fertilization shifted the RI classification from slight to sub-critical. In contrast, SH was significantly greater for manured than non-manured treatments, while RI was unaffected. Soil organic carbon (SOC) concentration was significantly (P ≤ 0.05) correlated with SH (r=0.74), but not with RI (r=-0.17). This suggested a closer association between the quantity of SOC and quantity of hydrophobic compounds (SH method) compared to the hydrophobic coatings inhibiting infiltration of water (RI method). No significant correlation between SH and RI (r=-0.09) suggests that SH is not a good predictor of SWR using the RI method. Overall, manure application increased SH and P fertilization shifted the RI classification from slight to sub-critical. In contrast, legume-cereal rotations had no influence on SH and SWR using RI method compared to continuous cereal.


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