Fig 3 - uploaded by Steven L Petersen
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Combined results for crested wheatgrass and bluebunch wheatgrass seedling densities over the course of the experiment, with results normalized by total germination for pots watered under a low or high watering regime, treated with or without wetting agent (WA). Significant differences (P < 0.05) at the end of the experiment are shown by unique letters.
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... For example, Bond (1972) provided one of the earliest reports to indicate significant reductions in barley (Hordeum vulgare L.) yield due to lack of germination in waterrepellent soils. Soil water repellency inhibited seedling germination and emergence of the non-native bunchgrass crested wheatgrass [Agropyron cristatum (L.) Gaertn.] and the native bunchgrass bluebunch wheatgrass [Pseduoroegneria spicata (Pursh) A. Love] by limiting access to available soil water (Madsen et al. 2009). ...
... In contrast, when the same wetting agent was used on wettable sand, rigid ryegrass germination was reduced (Osborn 1968). Madsen (2009) first coated native and non-native species seeds with soil surfactants to improve germination and emergence in wildfire-affected sites in the United States. In that study, the non-native bunchgrass crested wheatgrass seeds and the native bunchgrass bluebunch wheatgrass seeds were coated with an alkylpolyglycoside-ethylene oxide/propylene oxide block copolymer surfactant blend. ...
... 600 sec (Dekker et al. 2009) ( Fig. 3 and 4). Perennial ryegrass ('Shining Star') seed was coated at 10% w/w with a composition containing an alkylterminated block copolymer soil surfactant (Aquatrols Corporation of America, Paulsboro, NJ) utilizing a method described by Madsen (2009). Soil-surfactant-coated seed (SCS) and uncoated seed (CHK) of perennial ryegrass were sown at the recommended rate of 39.6 g m À2 (8 lbs 1,000 ft À2 ) (Turgeon and Kaminski 2019). ...
Soil water repellency inhibits seed germination and emergence, whereas soil surfactants improve the wettability of water-repellent or hydrophobic soils. An improvement in seed germination and emergence can occur when a soil surfactant is applied directly to the seed and/or to the water repellent soil at sowing. Therefore, a coating process was developed to utilize seed as a soil surfactant carrier. Greenhouse experiments were conducted to evaluate establishment of perennial ryegrass (Lolium perenne L.) seed coated with a soil surfactant (SCS = surfactant- coated seed), as compared to uncoated seed (CHK). Both SCS and CHK were sown in two hydrophilic substrates (100% sand [WSAND], 90:10% v/v sand:peat [WSP], and in two severely hydrophobic sands (100% hydrophobic stearic acid-treated sand [HSS], and hydrophobic 90:10% v/v sand:peat [HSP]). Due to the weight of the coating, SCS was sown at half the amount as compared to CHK; however, final turfgrass establishment in all rootzones with SCS was similar or better than CHK. In WSAND, WSP, and HSP, the volumetric water content was consistently higher in rootzones of SCS treatments versus CHK. SCS represents an opportunity to improve stand establishment and rootzone soil-water dynamics in challenging environmental conditions such as limited precipitation.
Species used in this study: Perennial ryegrass, Lolium perenne L.
... Soil water repellency (or hydrophobicity) is well documented in P-J woodland systems (Krammes and DeBano, 1965;Scholl, 1971;Roundy et al., 1978;Jaramillo et al., 2000;Rau et al., 2005;Madsen et al., 2008;Pierson et al., 2009;Madsen, 2009;Robinson et al., 2010). Th is soil condition may be ecologically advantageous to P-J trees by promoting bypass fl ow from precipitation inputs through select wettable patches, thus reducing evaporative losses near the soil surface (Madsen et al., 2008;Robinson et al., 2010). ...
... Post-fi re soil water repellency can act as an ecological threshold by increasing soil erosion (Krammes and Osborn, 1969;Letey, 2001;Leighton-Boyce et al., 2007;Pierson et al., 2009) and impairing the establishment of desired species within the fi rst few years aft er a fi re (Adams et al., 1970;Salih et al., 1973;Madsen, 2009). Understanding the extent, severity, and spatial patterns of post-fi re soil water repellency may help guide land managers in conducting restoration eff orts aft er a fi re. ...
Wildfires can create or intensify water repellency in soil, limiting the soil's capacity to wet and retain water. The objective of this research was to quantify soil water repellency characteristics within burned piñon–juniper woodlands and relate this information to ecological site characteristics. We sampled soil water repellency across forty-one 1,000 m2 study plots within three major wildfires that burned in piñon–juniper woodlands. Water repellency was found to be extensive—present at 37% of the total points sampled—and strongly related to piñon–juniper canopy cover. Models developed for predicting SWR extent and severity had R2adj values of 0.67 and 0.61, respectively; both models included piñon–juniper canopy cover and relative humidity the month before the fire as coefficient terms. These results are important as they suggest that postfire water repellency will increase in the coming years as infilling processes enhance piñon–juniper canopy cover. Furthermore, reductions in relative humidity brought about by a changing climate have the potential to link additively with infilling processes to increase the frequency and intensity of wildfires and produce stronger water repellency over a greater spatial extent. In working through these challenges, land managers can apply the predictive models developed in this study to prioritize fuel control and postfire restoration treatments.
... On steep slopes this saturation can enable water, soil, and debris to quickly flow downslope, resulting in extensive soil erosion, site degradation, and sediment pollution (DeBano 1981). Seeds that germinate in the upper wettable soil layer experience limited soil moisture availability as the water-repellent layer redirects soil moisture below the seedlings' root zone through breaks in the waterrepellent layer (Madsen 2010). Limited seedling establishment can expose a site to weed invasion (Young et al. 1976; Keeley et al. 2005) and subsequently impair ecological services (i.e., Arnold et al. 1964; D'Antonio and Vitousek 1992). ...
... Effects of wetting agent application and simulated mechanical soil disturbance on postfire water-repellent soil were evaluated in a glasshouse experiment conducted from 10 February through 22 April 2009 at Brigham Young University (BYU), Provo, Utah. Soil used in the study was collected from the subcanopy of burned Utah juniper trees [Madsen (2010) found that the upper layer of the soil was wettable down to 1.7 6 0.2 cm, after which the soil was water repellent, down an additional 4.5 6 0.2 cm. Estimates of the severity of the water-repellent layer using the water drop penetration time test (Krammes and DeBano 1965) showed that on average it would take 87.6 6 11.0 min (average and standard error of the mean) for a water drop to enter into the soil. ...
Soil water repellency can limit postfire reseeding efforts and thus increase the susceptibility of a site to weed invasion. We evaluated the effectiveness of wetting agents and simulated anchor chaining for improving seedling growth and survival in water-repellent soil, for the native perennial bluebunch wheatgrass (Pseudoroegneria spicata) and invasive annual cheatgrass (Bromus tectorum). Research was performed in a glasshouse, on 20-cm-diameter soil cores that were excavated from underneath burned Utah juniper (Juniperus osteosperma) trees. The experiment was arranged as a randomized split-plot design, with the two grass species sown separately under four soil treatments: 1) no treatment (control), 2) simulated anchor chaining (hereafter referred to as “till”), 3) wetting agent, and 4) till plus wetting agent. Soil water content was highest in the wetting agent treatment, lower for till, and lowest in the control. Overall, the response of bluebunch wheatgrass and cheatgrass was similar among treatments. At the conclusion of the study, wetting agent cores had twice as many seedlings as the control, while the till and control were similar. Despite a lower number of seedlings, tilling in general resulted in the same level of biomass as the wetting agent treatment. Overall, biomass in the till and wetting agent treatments was at least twofold higher than the control. No benefit was found in applying both till and wetting agent treatments together in comparison to just applying wetting agent. Because of a lack of correlation between glasshouse and field settings the results of this study need to be interpreted with caution. Our data may indicate that if cheatgrass is not already present on the site, anchor chaining or treating the soil with wetting agent can increase establishment of seeded species.
... On steep slopes this saturation can enable water, soil, and debris to quickly flow downslope, resulting in extensive soil erosion, site degradation, and sediment pollution (DeBano 1981). Seeds that germinate in the upper wettable soil layer experience limited soil moisture availability as the water-repellent layer redirects soil moisture below the seedlings' root zone through breaks in the waterrepellent layer (Madsen 2010). ...
... This use in urban landscapes has led to improvements in the effectiveness of wetting-agent chemicals for treating soil water repellency (Kostka 2000;Kostka and Bially 2005;Soldat et al. 2010;Oostindie et al. 2011). Recent evaluations within a glasshouse setting by Madsen (2010) provided evidence that wetting agents can improve ecohydrologic properties required for plant growth within postfire pinyon-juniper plant communities. Madsen (2010) found that water-repellent soil treated with wetting agent had significantly higher infiltration rates, soil water content, plant density, and biomass than a water-repellent soil without wetting agents. ...
... Recent evaluations within a glasshouse setting by Madsen (2010) provided evidence that wetting agents can improve ecohydrologic properties required for plant growth within postfire pinyon-juniper plant communities. Madsen (2010) found that water-repellent soil treated with wetting agent had significantly higher infiltration rates, soil water content, plant density, and biomass than a water-repellent soil without wetting agents. Subsequently, wetting agents may also provide an innovative approach for alleviating the effects of soil water repellency and promoting establishment of desired species. ...
Soil water repellency can limit postfire reseeding efforts and thus increase the susceptibility of a site to weed invasion. We evaluated the effectiveness of wetting agents and simulated anchor chaining for improving seedling growth and survival in water-repellent soil, for the native perennial bluebunch wheatgrass (Pseudoroegneria spicata) and invasive annual cheatgrass (Bromus tectorum). Research was performed in a glasshouse, on 20-cm-diameter soil cores that were excavated from underneath burned Utah juniper (Juniperus osteosperma) trees. The experiment was arranged as a randomized split-plot design, with the two grass species sown separately under four soil treatments: 1) no treatment (control), 2) simulated anchor chaining (hereafter referred to as "till"), 3) wetting agent, and 4) till plus wetting agent. Soil water content was highest in the wetting agent treatment, lower for till, and lowest in the control. Overall, the response of bluebunch wheatgrass and cheatgrass was similar among treatments. At the conclusion of the study, wetting agent cores had twice as many seedlings as the control, while the till and control were similar. Despite a lower number of seedlings, tilling in general resulted in the same level of biomass as the wetting agent treatment. Overall, biomass in the till and wetting agent treatments was at least twofold higher than the control. No benefit was found in applying both till and wetting agent treatments together in comparison to just applying wetting agent. Because of a lack of correlation between glasshouse and field settings the results of this study need to be interpreted with caution. Our data may indicate that if cheatgrass is not already present on the site, anchor chaining or treating the soil with wetting agent can increase establishment of seeded species.
... Lower soil moisture content in the water-repellent zone can decrease seed germination and increase seedling mortality [Osborn et al., 1967;Adams et al., 1970]. In addition, the decreased establishment within the first few years after a fire may leave resources available once water repellency is diminished [Briggs et al., 2002;Madsen, 2010]. ...
A new model for Mediterranean forest fire regime assessment is presented
and discussed. The model is based on the experimental evidence that fire
is due to both hydrological and ecological processes and that the
relative role of fuel load versus fuel moisture is an important driver
in fire ecology. Diverse scenarios are analyzed where either the
hydrological forcing or the feedback between fire and hydrological
characterization of the site is changed. The model outcome demonstrates
that the two way interaction between hydrological processes, biology and
fire regime drives the ecosystem toward a typical fire regime that may
be altered either by an evolution of the biological characterization of
the site or by a change of the hydrological forcing. This tenet implies
that not every fire regime is compatible with the ecohydrological
characterization of the site under study. This means that natural (non
human caused) fire cannot be modeled as an arbitrary external forcing
because the coupled hydrological and biological processes determines its
statistical characterization, and conversely, the fire regime affects
the soil moisture availability and the outcome of different species
competition under possible water stress. The new modeling approach here
presented, when provided by a proper model parameterization, can be able
to advance the capability in predicting and managing fires in ecosystems
influenced by climate and land use changes.
... Soil water repellency (or hydrophobicity) is well documented in P-J woodland systems (Krammes and DeBano, 1965;Scholl, 1971;Roundy et al., 1978;Jaramillo et al., 2000;Rau et al., 2005;Madsen et al., 2008;Pierson et al., 2009;Madsen, 2009;Robinson et al., 2010). Th is soil condition may be ecologically advantageous to P-J trees by promoting bypass fl ow from precipitation inputs through select wettable patches, thus reducing evaporative losses near the soil surface (Madsen et al., 2008;Robinson et al., 2010). ...
... Post-fi re soil water repellency can act as an ecological threshold by increasing soil erosion (Krammes and Osborn, 1969;Letey, 2001;Leighton-Boyce et al., 2007;Pierson et al., 2009) and impairing the establishment of desired species within the fi rst few years aft er a fi re (Adams et al., 1970;Salih et al., 1973;Madsen, 2009). Understanding the extent, severity, and spatial patterns of post-fi re soil water repellency may help guide land managers in conducting restoration eff orts aft er a fi re. ...
Soil water repellency is commonly found in piñon (Pinus spp.)-juniper (Juniperus spp.) (P-J) woodlands and may limit site recovery after a fire. Understanding the extent of this problem and the impact it has on vegetation recovery will help guide land managers in conducting their restoration efforts. In this study, we (i) examined the spatial distribution and severity of post-fire soil water repellency in a burned P-J woodland, (ii) related ecohydrologic properties to pre-fire tree canopy cover and post-fire vegetation establishment, and (iii) demonstrated a geographic information system (GIS)-based approach to extrapolate observed patterns to the fire boundary scale. During a 2-yr period, several soil and vegetative measurements were performed along radial line transects extending from the trunk of burned Utah juniper [Juniperus osteosperma (Torr.) Little] trees to twice the canopy radius. Results indicate that water repellency patterns are highly correlated with pre-fire tree canopy cover. Critical water repellency extended from the base of the tree to just beyond the canopy edge, while subcritical water repellency extended half a canopy radius past the edge of the critical water repellency zone. At sites where critical water repellency was present, infiltration rates, soil moisture, and vegetation cover and density were significantly less than non-water-repellent sites. These variables were also reduced in soils with subcritical water repellency (albeit to a lesser extent). Results were exported into a GIS-based model and used in conjunction with remotely sensed imagery to estimate the spatial distribution of soil water repellency at the landscape scale.
Lack of eucalypt recruitment is a key factor in the decline of forest and woodland remnants in low rainfall agricultural regions in Australia. Key to effective management of these forests is an understanding of the requirements and conditions that promote seed germination and seedling establishment (recruitment niche) and the persistence of lignotuberous sprouts (juvenile persistence niche). Recruitment is limited by the availability of safe microsites that are suitable for the germination and establishment of seedlings. The objective of this study was to investigate the microsites of established eucalypt seedlings and lignotuberous sprouts in healthy dry forests burnt in the previous 2–6 years in the Tasmanian Midlands. The recruitment niche differed significantly to the juvenile persistence niche while the juvenile persistence niche had characteristics similar to the general forest floor. Seedling microsites were characterised by: canopy gaps and ashbeds (95% of seedlings surveyed); a predominantly northerly aspect (75% of microsites); over 220° shelter with the average distance from a sheltering object being less than 30 cm and 80% of seedlings being sheltered by coarse woody debris; soil that was significantly softer (3.8 vs. 5.0 kgf/m2) and less water repellent (moderate vs. severe repellency) than the forest floor; and low cover of grass. These characteristics of seedling safe sites all affect moisture availability. Our results have important implications for the management of dry forest in order to facilitate eucalypt recruitment and persistence, suggesting the need for retention of coarse woody debris and the judicious use of fire.
