Relationships between soil temperatures and properties of fire in feathertop spinifex (Triodia schinzii (Henrard) Lazarides) sandridge desert in central Australia

2008 ◽  
Vol 30 (3) ◽  
pp. 317 ◽  
Author(s):  
B. R. Wright ◽  
P. J. Clarke

Soil temperatures during wildfires are known to influence seed bank and plant resprouting dynamics in arid Australian grasslands. Nevertheless, relationships between soil temperatures and factors such as fuel load, fuel type, season of burn, time-of-day and soil moisture are poorly understood. This study used small-scale experimental burns to determine the effects of these five variables on soil temperature profiles (0–4 cm) during fire in spinifex sandridge country in the Haasts Bluff Aboriginal Reserve, west of Alice Springs. Fuel load and type were found to strongly influence soil temperatures, with soils directly beneath Triodia hummocks experiencing more heating than hummock edges or between-hummock gaps, and soils beneath Triodia hummocks experiencing more heating than either mulga (Acacia aneura F.Muell. ex. Benth.) litter or Aristida holathera Domin. tussocks. Season and time-of-day also had strong effects on below-ground heating, with soil temperatures remaining elevated for longer periods during summer compared to winter burns, and day-time burns producing higher temperature maxima and longer durations of elevated soil temperatures than night burns. Soil moisture also had a strong impact on temperature profiles during fire, with high levels of soil moisture strongly reducing the soil heating during fire. These results indicate that the examined factors will strongly influence soil temperature regimes during spinifex wildfires. Hence, they are likely to affect the composition of plant assemblages in post-fire environments through their impacts on vegetative regeneration and on seed bank processes.

2013 ◽  
Vol 43 (3) ◽  
pp. 209-223 ◽  
Author(s):  
Jana Krčmáŕová ◽  
Hana Stredová ◽  
Radovan Pokorný ◽  
Tomáš Stdŕeda

Abstract The aim of this study was to evaluate the course of soil temperature under the winter wheat canopy and to determine relationships between soil temperature, air temperature and partly soil moisture. In addition, the aim was to describe the dependence by means of regression equations usable for phytopathological prediction models, crop development, and yield models. The measurement of soil temperatures was performed at the experimental field station ˇZabˇcice (Europe, the Czech Republic, South Moravia). The soil in the first experimental plot is Gleyic Fluvisol with 49-58% of the content particles measuring < 0.01 mm, in the second experimental plot, the soil is Haplic Chernozem with 31-32% of the content particles measuring < 0.01 mm. The course of soil temperature and its specifics were determined under winter wheat canopy during the main growth season in the course of three years. Automatic soil temperature sensors were positioned at three depths (0.05, 0.10 and 0.20 m under soil surface), air temperature sensor in 0.05 m above soil surface. Results of the correlation analysis showed that the best interrelationships between these two variables were achieved after a 3-hour delay for the soil temperature at 0.05 m, 5-hour delay for 0.10 m, and 8-hour delay for 0.20 m. After the time correction, the determination coefficient reached values from 0.75 to 0.89 for the depth of 0.05 m, 0.61 to 0.82 for the depth of 0.10 m, and 0.33 to 0.70 for the depth of 0.20 m. When using multiple regression with quadratic spacing (modeling hourly soil temperature based on the hourly near surface air temperature and hourly soil moisture in the 0.10-0.40 m profile), the difference between the measured and the model soil temperatures at 0.05 m was −2.16 to 2.37 ◦ C. The regression equation paired with alternative agrometeorological instruments enables relatively accurate modeling of soil temperatures (R2 = 0.93).


HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 667c-667
Author(s):  
Charlotte Mundy ◽  
Nancy G. Creamer ◽  
Jane Frampton

Regional growers have expressed an interest in the feasibility of producing potatoes on wide beds. Using wide beds decreases compaction and may increase water available to the crop due to the elimination of postplanting cultivation, or hilling, required in conventional rows. The middle row of wide beds may have cooler soil temperatures than the other rows in the bed. In addition, wide beds allowed for a planting density 1.5-times greater than conventional rows, which could significantly increase yields. Potatoes, `Atlantic', were planted mid-March into conventional rows on 38-inch centers and 6-foot 4-inch-wide beds, each bed with three rows. Plots were 50 feet long. Initial soil moisture contents in the middle of the bed, the outer rows of the bed and the conventional rows were not significantly different. Initial soil temperature data suggests that fluctuations in temperature are greatest in the conventional rows and least in the middle row of the wide beds. Soil temperature and soil moisture are reported. Marketable yields from wide beds are compared to marketable yields from conventional rows. Influence on potato size distribution and quality factors also are reported.


Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1747 ◽  
Author(s):  
Javier Lozano-Parra ◽  
Manuel Pulido ◽  
Carlos Lozano-Fondón ◽  
Susanne Schnabel

Interactions between land and atmosphere directly influence hydrometeorological processes and, therefore, the local climate. However, because of heterogeneity of vegetation covers these feedbacks can change over small areas, becoming more complex. This study aims to define how the interactions between soil moisture and vegetation covers influence soil temperatures in very water-limited environments. In order to do that, soil water content and soil temperature were continuously monitored with a frequency of 30 min over two and half hydrological years, using capacitance and temperature sensors that were located in open grasslands and below tree canopies. The study was carried out on three study areas located in drylands of Mediterranean climate. Results highlighted the importance of soil moisture and vegetation cover in modifying soil temperatures. During daytime and with low soil moisture conditions, daily maximum soil temperatures were, on average, 7.1 °C lower below tree canopies than in the air, whereas they were 4.2 °C higher in grasslands than in the air. As soil wetness decreased, soil temperature increased, although this effect was significantly weaker below tree canopies than in grasslands. Both high soil water content and the effect of shading were reflected in a decrease of maximum soil temperatures and of their daily amplitudes. Statistical analysis emphasized the influence of soil temperature on soil water reduction, regardless of vegetation cover. If soil moisture deficits become more frequent due to climate change, variations in soil temperature could increase, affecting hydrometeorological processes and local climate.


2014 ◽  
Vol 44 (3) ◽  
pp. 205-218
Author(s):  
Jana Krčmářová ◽  
Tomáš Středa ◽  
Radovan Pokorný

Abstract The aim of this study was to evaluate the course of soil temperature under the winter oilseed rape canopy and to determine relationships between soil temperature, air temperature and partly soil moisture. In addition, the aim was to describe the dependence by means of regression equations usable for pests and pathogens prediction, crop development, and yields models. The measurement of soil and near the ground air temperatures was performed at the experimental field Žabiče (South Moravia, the Czech Republic). The course of temperature was determined under or in the winter oilseed rape canopy during spring growth season in the course of four years (2010 - 2012 and 2014). In all years, the standard varieties (Petrol, Sherpa) were grown, in 2014 the semi-dwarf variety PX104 was added. Automatic soil sensors were positioned at three depths (0.05, 0.10 and 0.20 m) under soil surface, air temperature sensors in 0.05 m above soil surfaces. The course of soil temperature differs significantly between standard (Sherpa and Petrol) and semi-dwarf (PX104) varieties. Results of the cross correlation analysis showed, that the best interrelationships between air and soil temperature were achieved in 2 hours delay for the soil temperature in 0.05 m, 4 hour delay for 0.10 m and 7 hour delay for 0.20 m for standard varieties. For semi-dwarf variety, this delay reached 6 hour for the soil temperature in 0.05 m, 7 hour delay for 0.10 m and 11 hour for 0.20 m. After the time correction, the determination coefficient (R2) reached values from 0.67 to 0.95 for 0.05 m, 0.50 to 0.84 for 0.10 m in variety Sherpa during all experimental years. For variety PX104 this coefficient reached values from 0.51 to 0.72 in 0.05 m depth and from 0.39 to 0.67 in 0.10 m depth in the year 2014. The determination coefficient in the 0.20 m depth was lower for both varieties; its values were from 0.15 to 0.65 in variety Sherpa. In variety PX104 the values of R2 from 0.23 to 0.57 were determined. When using multiple regressions with quadratic spacing (modelling of hourly soil temperature based on the hourly near surface air temperature and hourly soil moisture in the 0.10-0.40 m profile), the difference between the measured and modelled soil temperatures in the depth of 0.05 m was -3.92 to 3.99°C. The regression equation paired with alternative agrometeorological instruments enables relatively accurate modelling of soil temperatures (R2 = 0.95).


1955 ◽  
Vol 33 (6) ◽  
pp. 595-627 ◽  
Author(s):  
D. R. Redmond

Cylindrosporium sp., isolated from dead yellow birch roots, inhibited the growth of another fungus isolated from mycorrhiza and dead roots. Growth rate of the former increased while that of the latter decreased with increased temperature above the optimum for rootlet, development. Twenty-four species of fungi were isolated from mycorrhiza. Seedlings grown aseptically in soil and in agar were inoculated with fungi isolated from dead and dying rootlets and from mycorrhiza, but none of the organisms displayed sufficient virulence to cause birch dieback. The optimum temperature for development of potted seedlings was about 18.5 °C. Increases or decreases of 2 °C. or more from the optimum for yellow birch development resulted in increased rootlet mortality, decreased frequency of mycorrhiza, and a thinner mantle of hyphae in mycorrhiza, followed by reduction in foliage vigor. Normal rootlet mortality of 6% in a 55-year-old yellow birch stand was increased to 19 and 60% by raising soil temperature 1° and 2 °C, respectively, above the normal during one summer. Soil moisture was not lowered a statistically significant amount by a 5 °C. increase until the sixth day following rain. Mycorrhiza existed on residual living roots in about the same proportion as on undisturbed root systems. The possibility that birch dieback may be the result of soil temperature increases is discussed. It is suggested that cutting practices in hardwood stands should remove all yellow birch trees or prevent increased temperatures in soil occupied by residual birch.


2009 ◽  
Vol 6 (5) ◽  
pp. 9977-10005 ◽  
Author(s):  
A. Jordan ◽  
G. Jurasinski ◽  
S. Glatzel

Abstract. The large scale spatial heterogeneity of soil respiration caused by differences in site conditions is quite well understood. However, comparably little is known about the micro scale heterogeneity within forest ecosystems on homogeneous soils. Forest age, soil texture, topographic position, micro topography and stand structure may influence soil respiration considerably within short distance. In the present study within site spatial heterogeneity of soil respiration has been evaluated. To do so, an improvement of available techniques for interpolating soil respiration data via kriging was undertaken. Soil respiration was measured with closed chambers biweekly from April 2005 to April 2006 using a nested design (a set of stratified random plots, supplemented by 2 small and 2 large nested groupings) in an unmanaged, beech dominated old growth forest in Central Germany (Hainich, Thuringia). A second exclusive randomized design was established in August 2005 and continually sampled biweekly until July 2007. The average soil respiration values from the random plots were standardized by modeling soil respiration data at defined soil temperature and soil moisture values. By comparing sampling points as well as by comparing kriging results based on various sampling point densities, we found that the exclusion of local outliers was of great importance for the reliability of the estimated fluxes. Most of this information would have been missed without the nested groupings. The extrapolation results slightly improved when additional parameters like soil temperature and soil moisture were included in the extrapolation procedure. Semivariograms solely calculated from soil respiration data show a broad variety of autocorrelation distances (ranges) from a few centimeters up to a few tens of meters. The combination of randomly distributed plots with nested groupings plus the inclusion of additional relevant parameters like soil temperature and soil moisture data permits an improved estimation of the range of soil respiration, which is a prerequisite for reliable interpolated maps of soil respiration.


1938 ◽  
Vol 16c (5) ◽  
pp. 203-213 ◽  
Author(s):  
G. B. Sanford

The effects of soil temperatures between 16° and 25 °C., and of soil moisture content between 19 and 40% of the moisture-holding capacity, on the virulence and type of attack of Rhizodonia Solani on young potato sprouts, were studied under controlled conditions and the results from 13 separate tests are discussed. The comparative growth rates of the pathogen on nutrient agar and in soil are outlined.At 25 °C. the disease diminished very abruptly. Between 23° and 16 °C., the pathogen appeared equally virulent throughout the range of soil moisture mentioned. The fluctuations which occurred in separate tests were not definite or consistent enough to warrant a conclusion that the virulence is greater at 16° than at 23°, or that a dry soil is more or less favorable to it than a wet one.In a fertile, steam sterilized loam, at medium moisture content, it required about ten days for the pathogen to grow as far as it did on the surface of a nutrient medium in four days. The growth rate at either 23° or 16 °C. was slightly higher in a wet soil than in one of medium moisture content, but in a dry soil the rate was somewhat less at 23° than at 16° in a medium or wet soil. Even in a fairly dry soil (19% moisture-holding capacity) at 16° the growth of the pathogen covered a distance of 5 cm. in ten days, which would appear adequate for infection of young sprouts from a set bearing viable sclerotia.The effort of the host to recover, by means of secondary and tertiary sprouts from the attacked primary sprout, was better in a wet soil than in a dry one at both 16° and 23 °C. The best effort was in a wet soil at 23°. A distinction is made between the effects of soil moisture and temperature in stimulating growth of the host, and their effect on parasitism itself.The remarkable tendency of the secondary sprouts to escape infection, regardless of soil temperature and soil moisture, is indicated. There was evidence that certain factors other than soil temperature and moisture may play an important role in the parasitism of R. Solani.


2012 ◽  
Vol 518-523 ◽  
pp. 4545-4551 ◽  
Author(s):  
Zhi Ping Fan ◽  
Xue Kai Sun ◽  
Fa Yun Li ◽  
Qiong Wang

Soil respiration as a major flux in the global carbon cycle plays an important role in regulating soil carbon pools. Global climatic changes including warming and a changing precipitation pattern could have a profound impact on soil respiration of terrestrial ecosystems, especially in arid and semiarid region where water is limited. We conducted a field experiment to simulate precipitation changes in a Mongolian pine plantation at Horqin sandy lands. The results indicated that, soil respiration was significantly affected by reduced rainfall treatment and water addition treatment in 9 experiment plots. Soil respiration rates in the water addition treatment plots increased about 40.7% to 166.4% and decreased about 34.0% to 70.0% in the reduced rainfall treatment plots. A model of the relationships between soil respiration and moisture with temperature was obtained by an empirical equation. Through operating the model, it was indicated that the highest soil respiration rate occurred at high soil water contents and intermediate soil temperatures in 9 plots. In the combined responses of soil respiration to soil temperature and soil moisture, soil temperature as a single independent variable explained only 29.9% of variance in soil respiration, and soil moisture was 71.3% of variance in soil respiration. It was concluded from our results that precipitation compared with soil temperature dominated more significantly the variability of ecosystem soil respiration in semiarid sandy lands.


Weed Science ◽  
1984 ◽  
Vol 32 (3) ◽  
pp. 402-407 ◽  
Author(s):  
Thomas B. Klevorn ◽  
Donald L. Wyse

Experiments were conducted in growth chambers to evaluate the effect of soil temperature and soil moisture on the distribution of14C-photoassimilates and14C-glyphosate [N-(phosphonomethyl) glycine] in quackgrass [Agropyron repens(L.) Beauv. ♯3AGRRE]. When14C-glyphosate was applied to leaves, the radioactivity was less in the rhizome buds of plants exposed to 7-C soil temperature than in plants exposed to 12- and 18-C soil temperatures after 2 days. In plants with leaves exposed to14CO2, the radioactivity from14C-photoassimilates was greatest in rhizomes and rhizome buds of plants at the 12-C soil temperature. As soil moisture levels were decreased, uptake of C-glyphosate into leaves declined, and transport to the daughter shoots, rhizomes, and rhizome buds was reduced. The concentration of14C-photoassimilates in the rhizome system of water-stressed quackgrass plants was similar to that in nonstressed plants. This study shows that the patterns of glyphosate distribution differ from those of photoassimilate distribution in quackgrass plants exposed to water stress.


Weed Science ◽  
1974 ◽  
Vol 22 (6) ◽  
pp. 571-574 ◽  
Author(s):  
Chu-Huang Wu ◽  
P. W. Santelmann ◽  
J. M. Davidson

The phytotoxicity of soil-applied terbutryn [2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine] to wheat (Triticum aestivumVill.) was significantly affected by soil moisture and soil temperature. Distribution coefficients (Kd) provided a better indication of the phytotoxicity of terbutryn to wheat than any single measured parameter contributing to herbicide adsorption by the soil. Soil temperatures and soil moisture levels suitable for good plant growth tended to enhance the phytotoxicity of terbutryn. No phytotoxic levels of terbutryn to wheat were detected in Teller sandy loam after 20 weeks of incubation at above 10C and 14% soil moisture by weight. However, phytotoxicity to wheat was observed in air-dry terbutryntreated soil after an incubation period of 20 weeks, regardless of incubation temperature. Significant quantities of terbutryn may remain in the field under dry soil conditions.


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