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<br />Imeson, A.C., Verstraten" J.M., van Mulligen, E.J., and Sevink, J., 1992, The effects of
<br />fire and water repellency on infiltration and runoff unde t Meditetranean type
<br />forest: Catena, v. 19, p. 345-361.
<br />Researchers performed a series of rainfall simulation experiments en burned and unburned
<br />soils .in the Selva region of Cataloda, Spain, to determine the relati,mship between hillslope
<br />hydrology and forest fIres. The stu::ly f()Und inftltration patterns to be similar for burned and
<br />unburned soils due to the presence of macropores (illustrated with photographs) in the
<br />vicinity of vegetation. These macropores rapidly conducted wate, to lower soil horizons,
<br />thus bypassing a water-repellentiayer near the surface, and preventi 19 high rates of hillslope
<br />runoff from occurring. In unbunecl locations, water was inte :cepted from litter and
<br />throughflow above water-repelle::lt AE or E horizons, while in burr ed areas the macropores
<br />intercepted overland flow from a water-repellent surface. Althou,;h runoff from burned
<br />slopes was higher over short ciismnces due to the loss of surface litter (and detention
<br />storage), the number of macropores dso increased in burned soils, thus providing more
<br />conduits for inftltration. Consequently, inftltration rates were high follow~1g forest fIres.
<br />However, burned soils also showed the potential to degrade over time and reduce porosity.
<br />In light of this, the paper concluded that more research is needed to study post-fire changes
<br />in soil properties.
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<br />Jex, G.W., Bleakley, B.H., HubeU, D.H., and Munro, L.L., 198!i, High humidity-
<br />induced increase in wa,:er repellency in some sandy soil,: Soil Science of
<br />America Joumal, v. 49, p.1177-1182.
<br />The degree of resistance to water penetration of diverse water-rep,:llent soils was found to
<br />be controlled by their moisture s:ates. Repellency was found tc, increase sharply when
<br />samples of a hyperthermic, uncoated Typic Quartzipsarnment soils were incubated at 100%
<br />relative humidity and to decline when wetted or incubated at hum dities less than 90%. A
<br />soil which was not water repellent: in the fIeld did not become re pellent at 100% relative
<br />humidity. Repellency increase ir, the soils was temperature dependent and could be
<br />eliminated by gamma irradiation, indicating a biological nature of t:le process. Application
<br />of antibiotics prior to incubation suggested that prokaryotic org2nisms were essential to
<br />repellency increase. A dilution study of the soil incubated at 1 OC % relative humidity for
<br />various periods revealed that the actinomycete population correla :ed best with repellency
<br />increase. Actinomycetes were fi)und to dominate the visual fIeld when the incubated soil
<br />was examined by electron microscopy. A model for repellency increase and decline, based
<br />on soil humidity, is offered.
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<br />John, P.H., 1978, Heat-induced water repellency in some New Zealand ]pumice soils:
<br />New Zealand Journal of Science, v. 21, p. 401-407.
<br />This paper discusses temperature-time combinations that produce varying degrees of (and
<br />destruction of) water repellency ir.. volcanic soils. The author not, os that only surface soils
<br />beneath stands of Pinus radiata a~d scrub produced repellency whe 1 heated, while sands of
<br />low organic content beneath paSl:Ure land exhibited no repellency af ter heat treatment. Also
<br />discussed are methods of measuring repellency and advantages of these methods, based on
<br />the papet by Watson and Letey (1970).
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