Catena 85 (2011) Contents lists available at ScienceDirect. Catena. journal homepage:

Transcription

1 Cten 85 (211) Contents lists ville t ScienceDirect Cten journl homepge: Wter repellency nd moisture content sptil vritions under Rosmrinus officinlis nd Quercus coccifer in Mediterrnen urned soil Eugeni Gimeno-Grcí,,, Jun Antonio Pscul, Jon Llovet c Centro de Investigciones sore Desertificción-CIDE (CSIC, Universitt de Vlènci, Generlitt Vlencin), Cmí de l Mrjl, s/n, 4647-All, Vlenci, Spin Fundciò Generl Universitt de Vlènci, Spin c Fundción Centro de Estudios Amientles del Mediterráneo (CEAM), Universitt d'alcnt, Deprtment d'ecologi, Cmpus de Snt Vicent del Rspeig Ap , Alcnt, Spin rticle info strct Article history: Received 2 Jnury 21 Received in revised form 1 Decemer 21 Accepted 3 Decemer 21 Keywords: Soil hydrophoicity Soil moisture content Wildfire Mediterrnen shrulnd Vritions in the distriution pttern of soil wter repellency (SWR) nd soil moisture re of mjor importnce for the hydrologicl nd geomorphologicl processes in Mediterrnen urned res, nd lso for their ecologicl implictions concerning to re-estlishment of the vegettion cover. This pper studies the influence of Rosmrinus officinlis L. nd Quercus coccifer L. vegetted ptches on SWR nd their reltionships with soil moisture content (SMC) nd soil orgnic mtter (SOM) in urned nd unurned clcreous soils of Mediterrnen shrulnd ecosystem, considering the first rinfll event occurred fter the wildfire in Les Useres (Cstellón, estern Spin). In urnt SSE fcing hillslope (73965 West, North), 8 microsites were selected under Q. coccifer nd 2 under R. officinlis. Three concentric zones were distinguished round the plnts: Zone I (stump), Zone II (intermedite) nd Zone III (re soil), showing differences on its soil surfce ppernce, which were considered for soil smpling nd for field moisture mesurements. In the nerest unurned zone, t the sme hillslope, 8 microsites for ech of the sme species were lso selected, on the sis tht they were representtive of the pre-fire conditions. The otined results imply tht fire cused significnt increse in SWR t R. officinlis stumps (mesured y mens of the wter drop penetrtion time test, WDPT). However, t urned Q. coccifer microsites, SWR ws destroyed y fire, t lest in the 2 mm soil frction (WDPT5 s). Results lso showed the presence of grdient from the highest WDPT nd SOM t Zone I to the lowest t Zone III for the two studied species, in tht wy tht re soil ws wettle t urned nd unurned microsites nd this fct is lso reflected on the sptil distriution of SMC. Field SMC showed n incresing grdient from the stumps towrds the outer zone, nd the differences etween SMC in the stumps nd re soil were greter from urned thn unurned microsites. Field SMC showed significnt nd negtive correltion coefficients with the WDPT nd SOM content for the two studied species. Moreover, positive reltionship etween WDPT nd SOM ws found. Prtil correltion nlysis t urned microsites reveled tht SMC nd WDPT re influenced y the SOM. The hydrologicl nd ecologicl implictions of these results re discussed. 21 Elsevier B.V. All rights reserved. 1. Introduction Due to the persistence, extensive dispersion, nd long term environmentl nd socioeconomic impcts, Mediterrnen wildfires hve een widely studied. The region could e considered s one where fires re mong of the most permnent threts to the environment in the northern hemisphere (Pscul Aguilr et l., 28). Within the specific scope of environmentl impcts, forest fires ct s triggering fctor to initite chnges in Mediterrnen ecosystems. Post-fire interctions etween different components of the vegettion/soil Corresponding uthor. Centro de Investigciones sore Desertificción-CIDE (CSIC, Universitt de Vlènci, Generlitt Vlencin), Cmí de l Mrjl, s/n, 4647-All, Vlenci, Spin. Tel.: ; fx: E-mil ddress: eugeni.gimeno@uv.es (E. Gimeno-Grcí). interfce hve een widely studied. Most works hve focused in the soil nd vegettion chnges, ssuming tht fire impcts ffect soil properties nd hydrologicl processes t different degrees, which re determined lrgely y fire severity nd the immedite post-fire rin regime (Gimeno-Grcí et l., 24, 27; Cmpo et l., 26; Doerr et l., 26; Llovet et l., 29). Thus, existing reserch hs een concentrted minly on infiltrtion, soil moisture storge nd runoff, which cn e significntly ffected y fire nd re directly relted with the soil wter cycle (Imeson et l., 1992; Ruio et l., 1997; Roichud et l., 2; González-Pelyo et l., 26; Cerdá nd Doerr, 25). The pttern of vegettion structure nd other soil surfce components (superficil stoniness, rock outcrops, soil crust nd re soil), lthough less studied in the literture, re n incresing recognized fctor of importnce regrding runoff genertion nd wter redistriution during the infiltrtion process, eing specilly /$ see front mtter 21 Elsevier B.V. All rights reserved. doi:1.116/j.cten

2 E. Gimeno-Grcí et l. / Cten 85 (211) emphsised where nded or spotted vegettion ptterns occur like in Mediterrnen lndscpes (Bergkmp et l., 1996; Vlentin nd Poesen, 1999; Clvo-Cses et l., 23; Boix-Fyos et l., 26; Arnu-Roslén et l., 28). The role of re soil ptches, outcrops nd the crusted re res etween vegettion clumps s runoff generting res (source res), nd the vegettion-covered res s wter-dsoring ptches (sink res) is one of the most importnt fetures in ptchy or nded vegettion types under Mediterrnen conditions (Cmmert, 24). This distriution of vegettion cover lso plys n importnt role in controlling the soil orgnic mtter inputs nd the soil moisture contents. Within this soil-vegettion interfce trnsition, the topsoil moisture pttern hs implictions for understnding environmentl processes such s infiltrtion regime, runoff genertion nd its superficil continuity cross slope, nd erosion nd sedimenttion driven y overlnd flow (Ktr et l., 27). At smll scles, soil moisture responds to vritions in soil properties, topogrphiclly driven chnges in lterl flow, rdition, nd vegettion (Western et l., 22). Soil vriles tht ffect infiltrtion nd wter storge include texture, structure, porosity, ulk density, orgnic mtter, nd so forth. Another soil property tht influences these processes is soil wettility. Soils in some vegettive types nd regions cn develop chrcteristic wter repellency, cused y hydrophoic, long-chined orgnic molecules, relesed from nturlly decomposing plnt litter, from the root zone nd the lef surfces of living plnts, from fungl hyphe nd soil microorgnisms, or y voltilistion nd condenstion of such compounds during fire (Doerr et l., 2). Soil wter repellency hs importnt effects in urned ecosystems, y modifying infiltrtion cpcity, wter movement in soil, nd on the post-fire erosion processes, minly rin drop splsh nd rill formtion (DeBno, 2; Doerr et l., 2; Shkesy nd Doerr, 26). Soil moisture influences wter repellency of the soil surfce in verticl nd lterl relloction of wter t the finest scles (Imeson et l., 1992). It seems tht cover density nd plnt species hve reltionship with the persistence nd distriution of SWR (DeBno, 1981; Doerr et l., 2), nd fire could ct s triggering fctor enhncing or decresing it relted to their severity. Although recent studies on clcreous Mediterrnen environments hve demonstrted tht wter repellency cn e found in oth urnt (Mtix-Soler nd Doerr, 24; Arcenegui et l., 28; Llovet et l., 29) nd nonurnt environments (Verheijen nd Cmmert, 27), the post-fire hydrologicl implictions of the fire-induced wter repellent soils, when the vegettion is spotted or there is ptchy shru mosic, is still poorly studied. Moreover, there re few studies tht consider the implictions of the first rinfll event on nturl wildfire res. The present pper studies the influence of urned nd unurned Rosmrinus officinlis nd Quercus coccifer vegetted ptches on soil wter repellency (SWR), nd their reltionships with soil moisture content (SMC) nd soil orgnic mtter (SOM), considering the first rinfll event occurred fter the wildfire. Since surfce SMC, SOM, nd SWR re influenced y vegettion nd fire, nd soil wter nd vegettion dynmics re functionlly relted, it could e expected to find some chnges on these vriles fter fire occurrence. 2. Mterils nd methods 2.1. Study re The study re is locted t Serr de l Creu, in the municiplity of Les Useres, 4 km of Cstellón city (Estern Spin). This re suffered wildfire from 28th August 27 to 7th Septemer 27. The totl ffected re covered 7482 h, of which 476 h corresponded to forest trees (with dominnce of Pinus hlepensis nd in lower extension Quercus rotundifoli); 5299 h were dominted y shrulnds nd the reminder surfce corresponded minly to griculturl rinfed res on terrces with lmond, olive nd cro trees (177 h). The re hs dry su-humid Mediterrnen-type climte with mrked dry period from June to Septemer. Men nnul temperture is 15.2 C nd the men nnul precipittion is 567 mm (dt from Vilfmés meteorologicl sttion). In this re, urned zone (73965 West, North) of 7 m wide y 16 m long, locted t 57 m.s.l. on South South Est fcing hillslope with 12º slope ngle ws selected. The soil is Rendzic Leptosol developed on Cretceous limestone, with sndy-lom texture, lkline ph (7.9) nd n orgnic mtter content of the Ah horizon of 7.6%. Despite fire, it ws possile to identify the presence of two unique shru species inside the plot: Q. coccifer nd R. officinlis, which re distriuted in ptchy mosic. The upper nd centrl prt of the plot is occupied y individuls of R. officinlis, seprted one from ech other t lest y.5 m. On oth sides of the plot, from meter 6 to 16(Fig. 1), Q. coccifer is distriuted in two longitudinl stripes, pproximtely of 2 3 m wide. Field oservtions nd mesurements reveled tht fire spred cross the shrulnd, urning rnches of 4 5 mm dimeter, nd consumed ll green leves of these species. Under Q. coccifer, the litter lyer ws lmost completely consumed, the dominnt sh colour ws grey nd white, nd the reminder twigs hd, generlly, men of 1 cm height nd 2 cm dimeter. In R. officinlis plces, the longest stnding twigs hd 8 cm height nd 2.5 cm dimeter on verge, the dominnt sh colour ws grey with some punctul res with white shes (minly close to the stump) (Fig. 2), nd the litter lyer ws prtilly consumed, remining some chrred leves, which helped to identify this species. Out of the urned plot, t its right nd left sides, unurned vegettion still stnds, dominted y shrulnd of m height, with Q. coccifer, R. officinlis, Anthyllis citysoides nd Brchypodium retusum s dominnt species, nd lso with some groves of Q. rotundifoli. In tht unurned zone, some vegetted ptches of the sme species s ove were selected s control microsites (see next epigrph). Unurned R. officinlis individuls hd men height of 9 cm nd 6 cm cnopy dimeter, wheres Q. coccifer vegettion ptches were 11 cm height nd 2 cm wide Soil smpling nd nlysis The ptchy mosic distriution of vegettion nd the differences on soil surfce ppernce hs een considered when soil smpling nd field moisture mesurements were mde. A totl of 44 microsites were selected: 16 t the unurned re (8 with R. officinlis nd other 8 with Q. coccifer) nd 28 microsites t the urned zone (2 with R. officinlis nd 8 dominted y Q. coccifer). The distriution of urned microsites is represented in Fig. 1. The selection of unurned microsites ws mde sed on the proximity nd similrity to the urned zone. At urned microsites three weeks fter the fire impct, it ws possile to distinguish three concentric zones round the chrred stumps showing differences on its soil surfce ppernce (Fig. 2). Zone I corresponds to the soil closest to the urned stump, with vrile dimeter etween 4 nd 6 cm, with grey nd white shes, nd where the litter lyer ws lmost completely consumed. Zone II is locted etween Zones I nd III, with vrile size from 1 to 3 cm; showing drk grey shes nd litter comustion lower thn Zone I. The Zones I nd II would correspond to the soil re covered y shru cnopy when unurned. Finlly, the Zone III, locted ll round the previous ones, is the most distnt from the stump nd corresponds to the re soil; it is chrcterised y the sence of shes nd more stones on the soil surfce thn the other zones. The soil ppernce on those different zones indicte grdient of fire severity, from the highest close to the stumps (Zone I) to the lowest on re soil (Zone III), ccording to the clssifiction criteri used y USDA Forest Service (Roichud et l., 2). At ech of the selected urned nd control microsites, soil smpling nd field soil moisture mesurements were mde. Additionl

3 5 E. Gimeno-Grcí et l. / Cten 85 (211) Distnce (m) SPAIN N Les Useres $ # CASTELLÓN DE LA PLANA VALENCIA# ALICANTE # Distnce (m) R4 R1 R3 R2 R6 R5 R7 R9 R1 R11 Q1 R13 R14 R15 Q3 R16 Q5 R17 R18 Q7 R19 R2 R8 R12 Q2 Q4 Q6 Q8 Quercus coccifer microsites (n=8) Rosmrinus officinlis microsites (n=2) Fig. 1. Loction of Les Useres study re nd schemtic representtion of urned vegettion t the selected plot. informtion is given in Fig. 2. A totl of 132 soil smples were collected from the first 2 cm of the minerl A horizon on 26th Septemer 27. Ash nd litter lyers were crefully removed with soft rush ( sptul ws used when necessry) prior the soil smpling. Soil smples were trnsported to the lortory nd ir-dried t room temperture Fig. 2. Exmple of the three soil smpling zones nd moisture mesurement points t one Rosmrinus officinlis microsite in Les Useres urned plot, three weeks fter the fire impct. Zone I: close to the stump; Zone II: intermedite re; Zone III: re soil. ( ): soil smpling points; nd (S) points for field soil moisture mesurements. (2 22 C). Ech soil smple ws divided in two susmples. One of them ws sieved to remove the N2 mm dimeter frction nd stored in irtight plstic oxes until nlysis (SOM, texture nd l-soil wter content). The other set of susmples were crefully dry hnd sieved, voiding the destruction of ggregtes, nd two soil frctions 2 mm nd.25 mm were seprted nd stored in irtight plstic oxes. This set ws used for soil wter repellency nlysis. The verge soil moisture of the ir-dried smples ws 3.8%. Field soil moisture content mesurements were mde one dy fter the first rinfll event fter fire (5 Octoer 27, 5 weeks fter the wildfire), when 11.5 L m 2 ws registered y the rin guge instlled close to the plot. Volumetric soil moisture content ws determined in the field y mens of the moisture meter HH2 with ThetProe sensor type ML2x, which responds to chnges in the pprent dielectric constnt of soil. Five redings were tken t ech of the three zones of the microsites ( totl of 66 mesures), seprted one from nother y 1 cm pproximtely (Fig. 2). Soil wter repellency (SWR) ws ssessed using the wter drop penetrtion time (WDPT) test (Letey, 1969). Only the ir-dry smples were nlysed in order to eliminte the dditionl influence of differing soil moisture contents on repellency vritions. Approximtely 3 g of ech soil smple ws plced into 6 mm dimeter nd 16 mm height plstic dish, leveled y gently shking nd tpping the dish on the ench top. Those dishes were exposed to the lortory tmosphere (2 22 C nd ~5% reltive humidity) for 24 h to eliminte potentil effects of ny vrition in preceding tmospheric humidity on soil (Doerr et l., 22; Mtix-Soler et l., 27). The WDPT test consisted in plcing 5 drops (~.5 ml) of distilled wter onto the soil smple surfce using

4 E. Gimeno-Grcí et l. / Cten 85 (211) hypodermic syringe nd recording the time tken for their complete penetrtion. The verge penetrtion time hs een considered s representtive of the WDPT of ech smple. WDPT were clssified y intervls nd clsses using the ctegories given in Tle 1 ccording to Bisdom et l. (1993). Smples with WDPT 5 s were clssed s wettle nd those WDPTN5 s s hydrophoic or wter repellent. Orgnic cron content ws determined in ll smples y oxidtion with potssium dichromte (Jckson, 1958). Orgnic mtter percentge ws otined multiplying the orgnic cron vlue y (Wlkley, 1947). Sturted soil wter content (pf ) ws determined for ech smple t lortory y Richrds' method (1947), nd the results were expressed in percentge of wter volume. Using this procedure, the ulk density for ech soil smple ws lso clculted. Soil texture ws ssessed fter destruction of the orgnic mtter y the hydrometer method (Bouyoucos, 1936) nd in this cse, for urned R. officinlis sites rndom selection of 24 smples were mde (8 in ech smpling zone) Sttisticl nlysis Normlity nd homogeneity of vrinces for soil dt were tested. The non-prmetric Kruskl Wllis test (P.5) ws used when normlity nd vrince homogeneity were not ssumed, like for WDPT dt set, to test the differences etween smpling zones; nd the U Mnn Whitney test (P.5) ws pplied to nlyse the difference etween the two studied species. ANOVA ws used to test the differences etween urned nd control tretments nd smpling zones for field soil wter content, orgnic mtter, sturted soil moisture content nd ulk density, ssuming norml distriution. Spermn's correltion coefficients (rho) nd prtil correltion nlysis were clculted to nlyse the reltionships etween soil vriles. 3. Results 3.1. Soil wter repellency (SWR) Results of SWR showed different frequency of wter repellent smples mongst the two plnt species tested, nd lso depending on fire effect t ech smpling zone in the microsites (Fig. 3). Considering the differences on soil surfce ppernce sed on the three concentric zones identified round the urned stumps, the lrgest repellency persistence ws found close to the chrred R. officinlis stumps (Zone I), where 1% of smples rendered SWR in the frction 2mm(Fig. 3A), with men WDPT of s (Fig. 4). The 85% of these smples showed slight SWR (6 swdpt6 s) nd the persistence of SWR ws etween 61 nd 3 s for the 1% of the smples, nd thus clssified s strong wter repellent (Tle 1). Only the 5% of urned R. officinlis smples t Zone I exhiited WDPT higher thn 6 s, nd were clssified s severe repellent soils (Tle 1). At the urned R. officinlis intermedite zone, only the 15% of smples were slightly wter repellent, nd ll the urned re soil smples (Zone III) were entirely wettle (Fig. 3A). Similr trends were otined from the soil frction.25 mm (Fig. 3C), where SWR ppers in the 1% nd 1% of R. officinlis smples from Zone I nd II, respectively. However, t unurned microsites, slight SWR ws present only in one of the 24 smples of the R. officinlis shrus. None of the smples tken t the urned Q. coccifer (frction 2 mm) exhiited SWR (Fig. 3B). In this cse, SWR ws only detected in the frction.25 mm, where the 37.5% of smples from urned Q. coccifer stumps hd WDPT N5 s(fig. 3D). However, t the unurned Q. coccifer microsites, SWR vlues were lwys highest round the stumps (men WDPT~56 s), nd decresed from the Zone I to the Zone III (re soil) (Fig. 4). The 75% of smples from unurned Q. coccifer t Zone I nd the 37.5% of smples from Zone II were clssified s slightly wter repellent (Fig. 3B). Nevertheless, for this species the soil frction.25 mm ws entirely wettle t unurned microsites (Fig. 3D). The results lso showed the presence of grdient from the highest WDPT t Zone I (round the stump) to the lowest WDPT t Zone III (re soil) for the two studied species (Fig. 4). It is importnt to highlight tht neither t urned nor unurned re soil microsites of the two studied species there ws ny soil wter repellency. Bre soil ws wettle nd this fct could hve influenced on the sptil distriution of soil moisture content. This sptil pttern is lso showed when SWR is sent (WDPT5 s), like t the urned Q. coccifer nd control R. officinlis microsites Field soil moisture content (SMC) nd their reltionship with soil wter repellency (SWR) nd soil orgnic mtter content (SOM) Field SMC mesured 1 dy fter the first rinfll event occurred in the study re (11 mm volume of rinfll), showed sttisticl significnt differences etween the two species microsites nd etween the three smpling zones from ech of them (Fig. 5A). Both control nd urned microsites showed the sme trend, with n incresing grdient from the stumps towrds the outer re soil zone. However, urned microsites showedthelowestvolumetricsmcinthezonei(stumps),withmen vlues of 18.3% in R. officinlis microsites nd 21.5% in the Q. coccifer ones, nd the highest SMC in the re soil, with 27.% in R. officinlis nd 29.5% in Q. coccifer microsites. Thus, the urned microsites showed lrger differences etween Zone I nd Zone III for the SMC (8 units) thn the unurned ones (3 units) (Fig. 5A). In ll cses, Zone II showed SMC vlues etween those from Zone I nd III. The sptil pttern of SOM ws similr etween species, independently they were urned or not, lthough vrying in mgnitude (Fig. 5C). The SOM vlues were lwys highest round the stumps nd decresed towrds the re soil zones. Moreover, the SOM contents were higher in unurned thn in urned microsites, especilly in the soil close to the stumps, where differences were sttisticlly significnt (Fig. 5C). Compring the SOM content etween wettle nd wter repellent soil smples for ech of the species, results showed tht urned R. officinlis soils tht were wter repellent (ll smples from Zone I), showed n verge SOM content of 8.8%. However, the urned Q. coccifer soil smples from stumps, with 1.3% of SOM content, were entirely wettle. On the other hnd, the unurned soil smples from this species tht were wter repellent, hd SOM contents of 14.9 nd 14.2% for stumps nd intermedite zones, respectively, wheres the wettle soil smples showed SOM contents rnging etween 9.8 nd 7.9%. Spermn's test showed significnt nd negtive correltion coefficients etween SMC nd WDPT for urned Q. coccifer (r=.65; P.1) nd R. officinlis microsites (r=.6; P.1) (Tle 2). Similr results etween field SMC nd WDPT were found in soil smples from control microsites (Tle 2). Spermn's correltion etween SMC nd SOM t urned nd control microsites, lso showed significnt nd Tle 1 Clsses of wter repellency nd wter drop penetrtion time (WDPT) intervls used in the present study (fter Bisdom et l., 1993). Clsses of wter repellency Wettle Slight Strong Severe Extreme WDPT intervls (s) N36 Log WDPT intervl N3.6

5 52 E. Gimeno-Grcí et l. / Cten 85 (211) (A) R. officinlis (frction <2mm) (B) Q. coccifer (frction <2mm) Bre soil (n=8) Bre soil (n=8) Burned Control Intermedite (n=8) Bre soil (n=2) Intermedite (n=2) Burned Control Intermedite (n=8) Bre soil (n=8) Intermedite (n=8) Stump (n=2) % 1% 2% 3% 4% 5% 6% 7% 8% 9% 1% % 1% 2% 3% 4% 5% 6% 7% 8% 9% 1% (C) R. officinlis (frction<.25 mm) (D) Q. coccifer (frction<.25 mm) Bre soil (n=8) Bre soil (n=8) Burned Control Intermedite (n=8) Bre soil (n=2) Intermedite (n=2) Burned Control Intermedite (n=8) Bre soil (n=8) Intermedite (n=8) Stump (n=2) % 1% 2% 3% 4% 5% 6% 7% 8% 9% 1% % 1% 2% 3% 4% 5% 6% 7% 8% 9% 1% Fig. 3. Frequency distriution of wter drop penetrtion time (WDPT, s) intervls for soil smples tken t urned nd control (unurned) microsites for Rosmrinus officinlis nd Quercus coccifer. (A) nd (B) soil frction 2 mm ; (C) nd (D) soil frction.25 mm. negtive correltion coefficients (Tle 2). Moreover, correltion coefficients etween WDPT nd SOM were lwys significnt nd positive. The prtil correltion nlysis with SOM s control vrile t urned microsites (Tle 2) reveled tht SMC nd log WDPT re influenced y this prmeter, ecuse the ove mentioned significnt correltions disppered. On the other hnd, the nlysis of the liner reltionship etween log WDPT nd SOM displyed the est fit with unurned Q. coccifer soil smples, showing tht when the ctul mount of orgnic mtter present in this soil is higher thn 13%, SWR ppers (Fig. 6). For the urned R. officinlis soil smples this reltionship ws less cler, nd the SOM threshold vlue for SWR could e estlished round 8% of SOM (Fig. 6) Sturted soil wter content (St-SWC) Results reveled tht there ws sptil pttern round the centrl stumps tht decrese from them towrds the re soil, following n Fig. 4. Men vlues for wter drop penetrtion time (WDPT) for soil smples considering the two studied species nd the distnce from the centrl stump. Stump, Intermedite nd Bre soil correspond with Zones I, II nd III, respectively. Stndrd error in rs. * Significnt differences with Kruskl Wllis Test (P.5). inverse trend thn the descried ove for SMC under field conditions. For instnce, urned R. officinlis microsites showed St-SWC of 62.8%, 6.3% nd 55.8% for stump, intermedite nd re soil zones, respectively (Fig. 5B). Similr trend ws found when nlysing urned Q. coccifer microsites. In this cse, there ws 6.8% volumetric wter content in the stump zones nd lowest wter content in re soil (52.5%), with sttisticl significnt differences etween them (P.5). In control (unurned) microsites these pttern ws lso reflected, lthough with lower differences etween zones thn tht oserved for the urned ones (Fig. 5B). 4. Discussion 4.1. Soil wter repellency (SWR) t unurned microsites It is commonly ccepted tht SWR is cused y orgnic compounds derived from living or decomposing plnts, soil microorgnisms nd fungi, which re susequently incorported into the soil. In sence of fire, certin evergreen tree types nd shrulnd species re known to exhiit lef wter repellency, which is cused y different microstructures nd epicuticulr wxes, lipids, resins nd/or romtic oils (Nienhuis nd Brthlott, 1997; Doerr et l., 2; Verheijen nd Cmmert, 27). Other studies found tht wter repellency is closely ssocited with the plnt root ctivity (Dekker nd Ristem, 1996; Doerr et l., 1998) or directly from the decomposition of orgnic mtter. Wter repellency hs lso een ssocited with fungl growth nd soil microorgnisms (Svge et l., 1972; Jex et l., 1985), which in turn cn e ssocited with specific vegettion types (Doerr et l., 2). Fungi re known to produce potentilly hydrophoic exudtes (Lin et l., 26) to protect ginst desicction stresses. Recent studies hd drwn the ttention in kind of fungl proteins, nmely hydrophoins tht re potent surfctnts nd hve the ility to self-ssemle t hydrophoic hydrophilic interfces into n mphiptic protein film (Rilling, 25). This suggests tht they my lso cot surfces in soils, such ggregtes, orgnic mtter nd fungl mycelium

6 E. Gimeno-Grcí et l. / Cten 85 (211) A vol. SMC (%) C SOM (%) c c A A B B A A B B Burned Control Burned Control Rosmrinus officinlis Quercus coccifer c c A A B B A B Burned Control Burned Control Rosmrinus officinlis Quercus coccifer Stump Intermedite Bre soil Stump Intermedite Bre soil B pf.1 (vol. SWC, %) D Bulk density (g cm -3 ) Burned Control Burned Control Rosmrinus officinlis Quercus coccifer c Burned Control Burned Control Rosmrinus officinlis Quercus coccifer Stump Intermedite Bre soil Stump Intermedite Bre soil Fig. 5. Men vlues for (A) volumetric field soil moisture content (vol. SMC); (B) sturted soil wter content (SWC); (C) soil orgnic mtter (SOM) nd (D) ulk density considering the two studied species nd the distnce from the centrl stump. Stndrd errors in rs. Different lower cse letters show the sttisticl significnt differences with Tukey Test (P.5) etween the different smpling zones: Stump, Intermedite nd Bre soil. Different cpitl letters show the sttisticl significnt differences etween urned nd control microsites with Mnn Whitney U Test (P.5). itself. Hydrophoin cotings on soil surfces my hve cused chnges in polrity from hydrophilic to more hydrophoic nd vice vers (Rilling, 25). In our cse, the presence of SWR in 87.5% of the unurned Q. coccifer smples seems to e relted minly to the presence of myceli into the litter lyer ( 5 cm depth) oserved in the field t the time of soil smpling, s lso reported y other uthors (Scott nd Vn Wyk, 199; Crockford et l., 1991; Arcenegui et l., 28), who found more severe SWR under the litter lyer of different plnt species. Mtix-Soler et l. (27) mesured tht the 3% of soil smples under Q. coccifer were wter repellent nd speculted tht this SWR could e due minly to fungi development. The sptil vriility of SWR found under unurned Q. coccifer microsites, with decresing grdient in WDPT from the centrl stump towrds the re soil (Fig. 4), hs lso een reported for other plnt species in severl studies crried out in nturl ecosystems. With sence of fire Keizer Tle 2 Spermn's correltion coefficients etween field soil moisture content (F-SMC), soil orgnic mtter (SOM) nd wter drop penetrtion time (WDPT) for Rosmrinus officinlis nd Quercus coccifer microsites. WDPT (s) F-SMC (%) Microsite Tretment F-SMC (%) S.O.M. (%) F-SMC prtil correltion Rosmrinus officinlis Quercus coccifer Rosmrinus officinlis Quercus coccifer Burned (n=6) ns Control (n=24) ns Burned (n=24) ns Control (n=24) ns Burned (n=6).64 Control (n=24).719 Burned (n=24).644 Control (n=24).462 ns: not significnt. Coefficient of prtil correltion etween log WDPT nd F-SMC controlling the effect for SOM. Significnt level for P.1. Significnt level for P.5. et l. (25) oserved this pttern under Eucliptus tress in Portugl, nd Verheijen nd Cmmert (27) found it under some unurned Mediterrnen shrulnd species (Stip tencissim, R. officinlis nd Anthyllis cytisoides) in Spin. Moreover, in the cse of unurned Q. coccifer there ws liner reltionship etween log WDPT nd SOM, nd threshold vlue of 13% SOM could e estlished to differentite etween wettle nd SWR smples (Fig. 6). Other uthors, in unurned ecosystems, found positive liner correltion etween SWR nd SOM content (Verheijen nd Cmmert, 27), which my e cused y incresed SOM equilirium levels proportionl to incresed SWR. Those uthors rgue tht n exponentil function would e expected if the only cuse of SWR ws the input of hydrophoic compounds from the plnts nd its ectorgnic profile. On the other hnd, the low percentge of SWR under unurned R. officinlis (4% of the smples) grees with the results otined y Mtix-Soler et l. (27) nd Verheijen nd Cmmert (27) in semirid Mediterrnen environments. R. officinlis is n evergreen romtic Mediterrnen shru tht contins essentil oils secreted y glndulr trichomes minly locted in their leves. This species hs high reltive wx input rte, which is sed on lef wx contents nd chrcteristics of the ectorgnic profile, s it hs een estimted y Verheijen nd Cmmert (27). Those uthors found the highest degree of SWR in the R. officinlis mulch lyer underneth the ectorgnic profile, menwhile in the soil crust under the mulch lyer, only two smples displyed wek SWR, concluding tht the source of wter repellency might e the ectorgnic profile. Other studies relted the high wettility of soil under unurned R. officinlis with lkline ph (Mtix-Soler et l., 27) nd fine soil texture, fctors tht hve een found to influence SWR. In our cse, soil phs under unurned R. officinlis microsites rnged etween 7.7 nd 7.98, nd the soil texture ws cly lom, with 27.9% of snd nd 43.9% of cly round the stumps. It seems tht those soil fctors enhnce the wettle conditions, which grees with the widely ccepted theory tht finest textured soils nd with lkline ph re less likely to develop SWR (DeBno, 1981), in spite tht, recently, severl reserchers in

7 54 E. Gimeno-Grcí et l. / Cten 85 (211) Log WDPT (s) Burned R. officicnlis Log WDPT =.1571 SOM R 2 = SOM (%) Log WDPT (s) Unurned R. officinlis Log WDPT =.143 SOM R 2 = SOM (%) Log WDPT (s) Burned Q. coccifer Log WDPT =.72 SOM R 2 = SOM (%) Log WDPT (s) Unurned Q. coccifer log WDPT =.1318 SOM R 2 = SOM (%) Fig. 6. Reltionship etween soil orgnic mtter content (SOM, %) nd persistence of wter repellency (log WDPT, s) of soil smples tken in Rosmrinus officinlis nd Quercus coccifer urned nd unurned microsites. Wettle ( ) nd wter repellent soil smples ( ). Mediterrnen environments hve identified SWR on unurned clcreous nd finest textured soils (Mtix-Soler nd Doerr, 24; Mtix-Soler et l., 27) Soil wter repellency (SWR) t urned microsites The persistence of SWR is dependent on the studied species. From the results otined in urned microsites, it is possile to infer tht the wildfire creted mosic of low nd moderte severity urnt res, ecuse of the non-uniformity of fire temperture nd durtion. At our study scle, this soil severity mosic seemed to e relted minly to the differences in fuel densities, litter depth, nd proly, moisture content of litter, iomss nd soil t the time of fire, etween the two studied species. Most studies report tht fire could induce, enhnce or destroy SWR depending on fire severity. The destruction of SWR hs een shown in lortory studies to occur ove soil temperture threshold of C for wide vriety of soils (Svge, 1974; Scholl, 1975; DeBno et l., 1976; Roichud nd Hungerford, 2; Grcí-Coron et l., 24). Our different results concerning SWR in unurned nd urned Q. coccifer microsites urned Q. coccifer microsites were entirely wettle (soil frction 2 mm), wheres the 87.5% unurned ones showed wter repellency (6WDPT181 s) suggest tht soil temperture surpssed the threshold of repellency destruction. The gretest iomss of Q. coccifer consumed during fire, supported y the remining height nd dimeter of rnches, the discontinuity nd/or scrce depth of the chrred litter lyer mesured in the field (1 cm when remin fter fire), the dominnce of whitish shes nd reduction in the SOM content when compred with control microsites (Fig. 5C), give lso evidence of more severe fire in those microsites. However, SWR ws found in the soil frction.25 mm from urned Q. coccifer stumps, which seems to e relted with the presence of fine hydrophoic interstitil orgnic mtter tht cn e concentrted when sieving the soil smple, s Mtix-Soler nd Doerr (24) hd suggested. The fire effect on the studied R. officinlis microsites enhnces SWR. In this cse, fire seems to e the triggering fctor responsile of the WDPT increment. Highest SWR persistence ws found, especilly, round the centrl stumps (Zone I) in oth soil dimeter frctions nlysed. We cn propose severl possile explntions to tht increse in SWR. Firstly, rosemry lef shows glndulr trichomes which contin romtic oils. Dominnt components re α-pinene, monoterpene hydrocron, nd cmphor s the min oxygented monoterpene (Bousi et l., 29). Fire could ffect those lef oil-contining glnds, cusing their rupture when were sujected to the therml stress, relesing those compounds. It ws likely to involve losses of more voltile compounds during fire, lthough others could e incorported into the soil surfce coting soil prticles which re rendered hydrophoic. Secondly, positive liner correltion etween SOM nd WDPT t R. officinlis microsites (Spermn's rho=.76, P.1, Tle 2) ws found. In some cses, the existence of wter repellency is not lwys proportionl to the mount of orgnic mtter present in soil (Fig. 6). In other words, the type or qulity of the orgnic mteril could hve more influence on developing SWR rther thn the totl mount of orgnic mtter or cron (Wllis nd Horne, 1992) present in the soil. Finlly, the soil frction.25 mm t urned R. officinlis stumps (Zone I) ws lso wter repellent for ll soil smples. Some studies hve found tht the finest frction of soil cn exhiit some degree of repellency (Doerr et l., 1996; de Jonge et l., 1999; Mtix-Soler nd Doerr, 24; Arcenegui et l. 28). It my e tht prticulte hydrophoic SOM is itself reltively fine, enhncing the degree of repellency in the fine sieved frction (de Jonge et l., 1999). Moreover, the mount of hydrophoic mteril supplied y fire impct, might e sufficiently high not only to cover the corser, ut lso much of the finer-sized prticles with n orgnic coting (Doerr et l., 1996, 2). Thus, it seems possile tht the hydrophoicity under R. officinlis urned stumps ws not only cused y hydrophoic coting on corser individul ggregtes, ut lso y coting on finer soil prticles, together with the existence of fine hydrophoic interstitil orgnic mtter. The finding tht the 15% of the strong repellent smples with WDPTN6 s were found in the 2 mm frction, wheres the other 85%

8 E. Gimeno-Grcí et l. / Cten 85 (211) of soil smples rendered slightly repellency, is in ccordnce with tht suggested y Bisdom et l. (1993) of hydrophoic coting on the corser soil prticles. On the other hnd, the results otined from the finest soil frction (.25 mm), where the 9% of R. officinlis smples were slightly wter repellent nd the reminder 1% showed strong nd severe wter repellency, seems to support the existence of orgnic fine hydrophoic mteril together with possile hydrophoic coting on the finest individul prticles. The nonexistence of SWR in re soil smples (Zone III) oth in R. officinlis nd Q. coccifer microsites, showed their very low susceptiility to ecome wter repellent, lthough those soils hd enough SOM content to develop wter repellency y urning. DeBno (1991) suggested tht ny soil contining more thn 2% of orgnic mtter is susceptile to ecoming wter repellent when heted. It hs to e tken into ccount tht rther thn the totl mount of orgnic mtter, the type or frction of the orgnic mtter (litter nd humus type, lipids, etc.) could e the responsile of SWR. In our cse, the sence of litter lyer t Zone III for oth species microsites, could explin prtilly the hydrophilic ehviour of those soil smples, greeing with the findings of Mtix-Soler et l. (28), who in lortory experience oserved no soil smple ecme wter repellent when urned without litter deris ddition Field soil moisture content (SMC), sturted soil wter content (St- SWC) nd soil orgnic mtter (SOM) nd their reltionship with soil wter repellency (SWR) At R. officinlis microsites, urned soil smples from Zone I hd the highest levels of orgnic mtter (8.8%) nd cly content (43.5%) (Tle 3), which led to etter ggregted soil structure, nd lso the ulk density of.78 g cm 3 (Fig. 5D) were indictive of high porosity nd therefore, it could e expected tht those fctors encourged soil moisture retention (Willims et l., 23). On the other hnd, smples from urned R. officinlis re soils (Zone III) hd lowest levels of SOM (4.8%) nd cly content (33.6%), nd incresed the ulk density (1. g cm 3 ) with corresponding decrese in porosity, so it could e expected lower SMC thn the smples from Zone I. However, the otined SMC results fter field mesurements showed tht the opposite occurs, indicting the influence of SWR in the moisture content nd on wter redistriution round the urned stumps, ecuse lrge (2 mm) nd fine (.25 mm) soil frctions from smples t urned R. officinlis stumps were entirely wter repellent. Q. coccifer urned microsites lso showed the lowest SMC t urned stumps nd the highest moisture content t the re soil zones, in spite tht t stumps, the SOM ws significntly higher (1.3%) thn in the intermedite (7.9%) nd re soil (5.7%) zones. Tle 3 Soil texture ( 2 cm depth) in urned nd control Rosmrinus officinlis nd Quercus coccifer microsites. Men vlue ±stndrd error. Microsite Position Snd (%) Silt (%) Cly (%) Burned R. officinlis Stump 3.1± ± ±1.5 Intermedite 35.± ± ±2.7 Bres oil 39.9± ± ±1.6 Control R. officinlis Stump 27.9± ± ±2.4 Intermedite 29.1± ± ±2.2 Bres oil 36.9± ± ±2.5 Burned Q. coccifer Stump 23.1± ± ±2.7 Intermedite n.d. n.d. n.d. Bres oil 4.6± ± ±1.7 Control Q. coccifer Stump 17.8± ± ±3.7 Intermedite 24.9± ± ±3.4 Bres oil 34.3± ± ±4.3 Mens not shring the sme letter indictes the existence of sttisticl significnt differences with Tukey Test t P.5 etween smpling zones from ech species microsite. n.d.: not determined. Soil from stumps hd the lrgest cly content (4.6%) (Tle 3) nd the lowest ulk density (.76 gcm 3 ) compred with the surrounding re soil zones (Fig. 5D), so it could e expected those soil vriles contriute to increse moisture content. In this cse, the influence of hydrophoicity on SMC is less cler, ecuse SWR ws only detected in soil frction.25 mm. A possile explntion for the sptil differences in SMC contents could e tht the lrge SOM content (1.3%) nd the existence of fine hydrophoic mteril present in the urned Q. coccifer stumps (Mtix-Soler nd Doerr, 24), seems to e sufficient to diminish the wettility of those soil ggregtes, lowering the SMC in those zones during the rinfll event studied. However, the results otined when soil smples where sturted in the lortory showed tht the lrgest SOM nd cly contents, the highest St-SWC ws found. It is often stted tht repellency disppers fter prolonged wet periods, nd some studies hve suggested soil moisture threshold t which soils cese to e wter repellent (DeBno, 1981; Doerr nd Thoms, 2; Huffmn et l. 21). The finding tht under lortory sturtion conditions the soil from stump zones showed lrger wter content thn the re soil zones indictes tht the threshold for the elimintion of SWR is surpssed, nd supports the influence of hydrophoicity on the SMC under field conditions. The differences in SMC etween stumps, intermedite nd re soil zones fter the studied rinfll event, with cler grdient of incresing soil moisture from the stump towrds the re soil my e explined y two mechnisms. On the one hnd, the highest SOM content, including the fine hydrophoic mteril t Zone I (stumps), nd the lrgest persistence of wter repellency in some sites, my decrese the wettility of ggregtes, slowing their wetting rtes (Chenu et l., 2), which my not completely occur during the studied rinstorm. This seems to e occurred minly t control or unurned microsites, where the SMC grdient ws smoother thn in urned ones. In this cse, dditionl sptil vriility fctors like the vritions in the storge cpcity of the cnopy, litter nd duff lyers, will determine how much wter will e delivered to the soil surfce during rinfll event (Doerr nd Moody, 24). Those fctors, together with the hydrophoic nture of R. officinlis litter nd the undnt fungi myceli in Q. coccifer litter, seems to e the min fctors influencing SMC grdient in oth unurned microsites. On the other hnd, the infiltrtion cpcity of urned soils could e reduced y their hydrophoic nture, especilly under R. officinlis, nd cuses rinwter to pond t the stump zone, nd thus increses overlnd flow (McN et l., 1989; Imeson et l., 1992; Cerdá nd Doerr, 27), which it could e expected to infiltrte once the closest re of wettle soil is reched, tht corresponds to the intermedite nd re soil, incresing the SMC in those zones. In this cse, s severl uthors found (Ktr et l., 27), the surfce soil moisture on the first dy fter rinfll my represent distriution of source nd sink res of wter round shrus during rinfll. Considering this rinfll event, the wter repellent soil closest to urned stumps could ct s source of runoff, which is trnsferred towrds the re soil res. If these re soil lso cts s source of runoff it must depend on rinfll chrcteristics, especilly rin intensity (Clvo-Cses et l., 23). In ddition, for the two studied species microsites, it is necessry to consider the existence of root chnnels, mcropores, crcks nd niml orrows with the development of preferentil flow pthwys tht ffect the wter movement into the soil, nd could enhnce deeper wter infiltrtion round the stump res (Doerr nd Moody, 24; Doerr et l., 26). The sptil vriility of SWR nd SMC t the finest scle found in this study could hve importnt implictions in the reestlishment of the vegetted cover fter the fire impct. The sence of SWR t the urned Q. coccifer stumps llowed it to retin 14.6% more wter thn soil round R. officinlis stumps, which proly ply n importnt role in the regenertion of this resprouter species, together with other post-fire

9 56 E. Gimeno-Grcí et l. / Cten 85 (211) environmentl dvntges like the sudden relese of nutrients coming from shes, more light nd more open spce ville, etween other fctors. In semirid Mediterrnen res where fter summer wildfires there is riny seson in utumn, the sptil vriility for SWR, SMC nd SOM found round the shrus my ply n importnt role in the infiltrtion nd sptil distriution of wter into the soil. 5. Conclusions Fire promoted different effect on surfce soil wter repellency t this prticulr site nd it ws relted to the plnt species. The persistence of soil wter repellency ws found to vry widely in short distnces round the shrus s influenced y mosic of fire severity in the different plnt species microsites. The more severe fire t Q. coccifer stumps led to the comustion of orgnic mtter nd ssocited hydrophoic compounds, rendering the soil surfce wettle (soil frction 2 mm), which ws the opposite to the oserved in those unurned microsites, where the 75% of soil smples were wter repellent. The lower fire severity t R. officinlis microsites seemed to hve produced the relese of hydrophoic compounds from their leves nd litter, rendering the soil surfce wter repellent t the stump zone for ll smples in the two soil frctions nlysed (2 nd.25 mm). However, the unurned R. officinlis microsites were wettle. Moreover, the entire re soil smpling zones round the urned or unurned centrl stumps of oth plnt species were fully wettle, nd this fct hd influenced on the sptil distriution of soil moisture content. The mosic of field soil moisture distriution ws inversely relted to the soil wter repellency nd to the soil orgnic mtter content, nd it could reflect the potentil runoff soil ptches in the first rinfll event fter the wildfire. The sptil vriility of soil wter repellency nd soil moisture content t short distnces should imply tht runoff genertion would e very ptchy round the urned stumps nd the overlnd flow generted in these res could e trnsferred towrds the re soil res, which incresed their soil moisture content one dy fter the first rinfll event registered fter the wildfire. The existence of this sptil pttern of res with contrsting soil properties nd hydrologicl response should ply n importnt role on the wter redistriution nd lso on the re-estlishment of the vegettion cover in this Mediterrnen urned re. Arevitions SWR soil wter repellency SMC soil moisture content SOM soil orgnic mtter WDPT wter drop penetrtion time St-SWC soil wter content under sturtion conditions Acknowledgements This reserch ws crried out s prt of the project Estudio de l vriilidd espcil de los ptrones de humedd del suelo en zons incendids de l Comunidd Vlencin: su relción con l respuest hidrológic y erosiv del suelo y con l regenerción de l vegetción, GV/ 27/63, funded y the Generlitt Vlencin, nd lso ws supported y Progrm Rmón y Cjl from the Spnish Ministerio de Cienci e Innovción. Fundción CEAM is supported y Generlitt Vlencin nd Bncj, s well s y the Progrm CONSOLIDER-INGENIO (GRACCIE Project). We lso would like to cknowledge Mite Silvestre nd Roger Gru for their field nd lortory ssistnce. References Arcenegui, V., Mtix-Soler, J., Guerrero, C., Zornoz, R., Mtix-Beneyto, J., Grcí- Orenes, F., 28. Immedite effects of wildfires on wter repellency nd ggregte stility in Mediterrnen clcreous soils. Cten 74 (3), Arnu-Roslén, E., Clvo-Cses, A., Boix-Fyos, C., Lvee, H., Srh, P., 28. Anlysis of soil surfce component ptterns ffecting runoff genertion. An exmple of methods pplied to Mediterrnen hillslopes in Alicnte (Spin). Geomorphology 11, Bergkmp, G., Cmmert, E.L.H., Mrtinez-Fernndez, J., Wter movement nd vegettion ptterns on shrulnd nd n ndoned field in two desertifiction thretened res in Spin. Erth Surfce Processes nd Lndforms 21, Bisdom, E.B.A., Dekker, L.W., Schoute, J.F.Th., Wter repellency of sieve frctions from sndy soils nd reltionships with orgnic mteril nd soil structure. Geoderm 56, Boix-Fyos, C., Mrtínez-Men, M., Arnu-Roslen, E., Clvo-Cses, A., Cstillo, V., Alldejo, J., 26. Mesuring soil erosion y field plots: understnding the sources of vrition. Erth-Science Reviews 78, Bousi, N., Vin, M.A., Ferht, M.A., Petitcols, E., Meklti, B.Y., Chemet, F., 29. Comprison of two isoltion methods for essentil oil from rosemry leves: hydrodistilltion nd microwve hydrodiffusion nd grvity. Food Chemistry 114, Bouyoucos, G.J., Directions for mking mechnicl nlysis of soils y the hydrometer method. Soil Science 42, Clvo-Cses, A., Boix-Fyos, C., Imeson, A.C., 23. Runoff genertion, sediment movement nd soil wter ehviour on clcreous (limestone) slopes of some Mediterrnen environments in southest Spin. Geomorphology 5, Cmmert, E.L.H., 24. Scle dependent thresholds in hydrologicl nd erosion response of semi-rid ctchment in southest Spin. Agriculture, Ecosystems & Environment 14, Cmpo, J., Andreu, V., Gimeno-Grcí, E., González, O., Ruio, J.L., 26. The occurrence of soil erosion fter repeted experimentl fires in Mediterrnen environment. Geomorphology 82, Cerdá, A., Doerr, S.H., 25. Long-term soil erosion chnges under simulted rinfll for different vegettion types following wildfire in estern Spin. Journl of Wildlnd Fire 14, Cerdá, A., Doerr, S.H., 27. Soil wettility, runoff nd erodiility of mjor dry- Mediterrnen lnd use types on clcreous soils. Hydrologicl Processes 21, Chenu, C., Le Bissonnis, Y., Arrouys, D., 2. Orgnic mtter influence on cly wettility nd soil ggregte stility. Soil Science Society of Americ Journl 64, Crockford, S., Topdilis, S., Richrdson, D.P., Wter repellency in dry sclerophyll forest-mesurements nd processes. Hydrologicl Processes 5, de Jonge, L.W., Jcosen, O.H., Moldrup, P., Soil wter repellency: effects of wter content, temperture nd prticle size. Soil Science Society of Americ Journl 63, DeBno, L.F., Wter repellent soils: stte-of-the-rt. Generl Technicl Report PSW-46. USDA Forest Service, Pcific Southwest Forest nd Rnge Experimentl Sttion Berkeley, Cliforni. DeBno, L.F., The effects of fire on soil properties. Generl Technicl Report. INT- 28 USDA Forest Service, Berkeley, Cliforni, pp DeBno, L.F., 2. The role of fire nd soil heting on wter repellency in wildlnd environments: review. Journl of Hydrology , DeBno, L.F., Svge, S.M., Hmilton, A.D., The trnsfer of het nd hydrophoic sustnces during urning. Proceedings of the Soil Science Society of Americ 4, Dekker, L.W., Ristem, C.J., Vrition in wter content nd wetting ptterns in Dutch wter repellent pety cly nd clyey pet soil. Cten 28, Doerr, S.H., Moody, J.A., 24. Hydrologicl effects of soil wter repellency: on sptil nd temporl uncertinties. Hydrologicl Processes 18, Doerr, S.H., Thoms, A.D., 2. The role of soil moisture in controlling wter repellency: new evidence from forest soils in Portugl. Journl of Hydrology , Doerr, S.H., Shkesy, R.A., Wlsh, R.P.D., Soil wter repellency vritions with depth nd prticle size frction in urned nd unurned Eucliptus gloulus nd Pinus pinster forest terrin in the Águed sin, Portugl. Cten 27 (1), Doerr, S.H., Shkesy, R.A., Wlsh, R.P.D., Sptil vriility of soil wter repellency in fire-prone euclyptus nd pine forest, Portugl. Soil Science 163, Doerr, S.H., Shkesy, R.A., Wlsh, R.P.D., 2. Soil wter repellency: its cuses, chrcteristics nd hydro-geomorphologicl significnce. Erth Science Reviews 51, Doerr, S.H., Dekker, L.W., Shkesy, R.A., Ristem, C.A., Brynt, R., 22. Wter repellency of soils: the influence of mient reltive humidity. Soil Science Society of Americn Journl 66, Doerr, S.H., Shkesy, R.A., Blke, W.H., Chfer, C.J., Humphreys, G.S., Wllrink, P.J., 26. Effects of differing wildfire severities on soil wettility nd implictions for hydrologicl response. Journl of Hydrology 319, Grcí-Coron, R., Benito, E., de Bls, E., Vrel, M.E., 24. Effect of heting on some soil physicl properties relted to its hydrologicl ehviour in two north-western Spnish soils. Interntionl Journl of Wildlnd Fire 13, Gimeno-Grcí, E., Andreu, V., Ruio, J.L., 24. Sptil ptterns of soil tempertures during experimentl fires. Geoderm 118, Gimeno-Grcí, E., Andreu, V., Ruio, J.L., 27. Influence of vegettion recovery on wter erosion t short nd medium-term fter experimentl fires in Mediterrnen shrulnd. Cten 69 (2), González-Pelyo, O., Andreu, V., Cmpo, J., Gimeno-Grcí, E., Ruio, J.L., 26. Hydrologicl properties of Mediterrnen soil urned with different intensities. Cten 68, Huffmn, E.L., McDonld, L.H., Stednick, J.D., 21. Strength nd persistence of fireinduced soil hydrophoicity under ponderos nd lodgepole pine, Colordo Front Rnge. Hydrologicl Process 15,