South Aspects Research Articles

Effects of Pheromone Release Rate and Trap Placement on Trapping of Agrilus planipennis (Coleoptera: Buprestidae) in Canada.

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a devastating insect pest in its introduced range. A trapping system that increases trap catches or detection rates in low-density populations would be beneficial for survey programs. Five trapping experiments were conducted to investigate factors influencing capture rates of male beetles on dark green traps baited with the A. planipennis pheromone, (3Z)-dodecen-12-olide ((3Z)-lactone), plus the green leaf volatile, (3Z)-hexenol. Low doses (0.001-1.0 mg) of (3Z)-lactone + (3Z)-hexenol did not consistently increase captures of male A. planipennis. In other experiments, mean captures of males were significantly higher on traps baited with a moderate dose (3.0 mg/septum) of (3Z)-lactone + (3Z)-hexenol, compared with lower doses (0.001, 0.1, and 1.0 mg) or (3Z)-hexenol alone. Next, we demonstrated that addition of (3Z)-lactone to traps baited with (3Z)-hexenol resulted in significantly greater increases in male captures when pairs of traps were placed on the same tree, than when traps were placed on adjacent trees. Moreover, significantly more A. planipennis were captured on pheromone-baited traps placed in the southern versus northern aspect of the crown. These results highlight the importance of experimental set-up for elucidating lure treatment effects and also suggests the (3Z)-lactone may be more active at close range. Our findings increase our understanding of the pheromone ecology of this species and lend support toward the use of dark green traps baited with 3.0 mg (3Z)-lactone + (3Z)-hexenol deployed in the south aspect of the canopy for detection programs for this insect.

Resource separation by mountain ungulates on a landscape modified by fire

AbstractFire restructures plant communities and can be an important modifier of ecosystems. Increases in forage quantity and quality in burned areas attract large ungulates, and may result in changes to animal distributions. In mountainous northern British Columbia where prescribed fire is used to enhance ungulate range, there is concern that expanding elk (Cervus elaphus) populations will move in response to burning into the traditional ranges of another grazing species, Stone's sheep (Ovis dalli stonei), and have adverse effects on them. We compared patterns of resource selection and use by both species on a landscape with 138 prescribed burns varying from 0 to 31 years of age. Seasonal range sizes of global positioning system (GPS)‐collared individuals were smallest in winter and late winter and largest in summer for both female Stone's sheep and elk. Both species selected for south aspects and against conifer stands in all seasons. Stone's sheep selected for burned areas in fall, winter, and late winter and selected to be close to a burn in every season except summer. Elk selected for burned areas in every season, with the highest selection for burn‐shrub areas. Stone's sheep typically used younger burns, whereas elk were less specific and often used older burns. The highest potential for seasonal overlap in the use of burned areas occurs during winter and late winter, but Stone's sheep and elk at current population levels overlap minimally because they partition their use of the landscape through elevation and topography. Stone's sheep always selected and used steeper rugged terrain than elk, and were at higher elevations, often in rocky areas. Elk avoided alpine and rocky areas, and were at lower elevations than Stone's sheep, on flatter less rugged terrain. We recommend continued monitoring of post‐fire effects on resource selection and use by these sympatric grazers, particularly relative to the distribution of expanding elk populations, which could enable competitive interactions and change predator‐prey dynamics. © 2015 The Wildlife Society.

Colonisation and succession of marine biofilm-dwelling ciliates in response to environmental variation

Protozoan assemblages and successional dynamics are important components of biofouling that require better understanding. We studied marine ciliates in temperate Australia as they colonised artificial substrates for 21 d during 2 different seasons, with 2 different aspects of orientation. Sessile and planktonic taxa established within 7 d, whereas vagile taxa colonised throughout the period. Abundances reached 366 ciliates cm-2. Colonies of the peritrichs Zoothamnium and Vorticella, and the hypotrichs Aspidisca and Euplotes were the most abundant. The north aspect received more light than the south aspect during summer, but assemblages did not differ significantly. Assemblage structure was different between seasons, and it developed more quickly and reached greater abundances during summer. A storm late in summer abruptly reduced abundances and affected functional groups differently, but diversity was largely unaffected. Thus, diversity of an established assemblage can be maintained through disturbances, despite abundances being subject to great fluctuation.

Quantifying the effects of topographic aspect on water content and temperature in fine surface fuel

This study quantifies the effects of topographic aspect on surface fine fuel moisture content (FFMC) in order to better represent landscape-scale variability in fire risk. Surface FFMC in a eucalypt forest was measured from December to May (180 days) on different aspects using a novel method for in situ monitoring of moisture content (GWClit) and temperature (Tlit) in litter. Daily mean GWClit varied systematically with aspect. North (0.07 ≤ GWClit ≤ 1.30 kg kg–1) and south (0.11 ≤ GWClit ≤ 1.83 kg kg–1) aspects were driest and wettest respectively, whereas east and west were somewhere in between. On the warmest day (38.9°C), the maximum Tlit on north (43.7°C) and south (29.8°C) aspects differed by 13.9°C. Aspect-driven variation in Tlit and GWClit is exacerbated by vegetation, which increases markedly in density with decreasing solar exposure. GWClit was below fibre saturation point (<0.35 kg kg–1) on 49 and 128 days on south and north aspects, respectively, demonstrating that fuels beds are often in different stages of drying and therefore subject to different hydrological processes depending on landscape position. This terrain-related variability in moisture dynamics strongly affects the spatial connectivity of fuels, and may be more important for predicting landscape-scale burn outcomes than sub-daily fluctuations at a point.

Relationship between leaf traits of Melica przewalskyi and slope aspects in alpine grassland of Qilian Mountains, China

Aims Variations in leaf characteristics can reflect plant acclimation to environments. We aimed to examine the relationship between leaf traits of Melica przewalskyi and slope aspect. Methods In alpine grassland of Qilian Mountains, Gansu Province, China, 80 plots were sampled at intervals of 20 m along eight aspects. Latitude, longitude and altitude of each plot were recorded by GPS. At each plot, 10 individuals of M. przewalskyi were random selected and harvested for measurements of leaf mass, leaf area, and leaf volume. A digital elevation model (DEM) was constructed to extract elevation, aspect, and slope for each plot by ArcGIS. The 80 plots were divided into groups of north, east, west and south aspect. Values for leaf traits were log-transformed. the standardized major axis (SMA) estimation method, was used to examine the covariation among leaf traits. Important findings Leaf area and leaf volume decreased significantly as aspect turns from north to east, from east to west, and from west to south, but not so for leaf mass, suggesting that leaf thickness increased as slope aspect changes, and thus led to the smaller and thicker leaves on the south-facing slope than that on north-facing slope. A clear allometric relationship between leaf mass and leaf area was found only on the south-facing slope where increase in leaf mass was greater than that in leaf area. While on other slope aspects, an isometric relationships between them was observed. The allometric relationship between leaf mass and leaf volume was found on all four aspects, with the growing speed of leaf volume greater than that of leaf mass, and a rising SMA slope. We can conclude that variations in leaf traits of M. przewalskyi with slope aspect could reflect plant acclimation.

Trade-off relationship between root forks and branch angle of Reaumuria songarica on different aspects of slopes

Aims Root architecture is a major determinant in root spatial distribution and soil searching efficiency, may re- flect plant strategies to adapt to the environments. Our objective was to examine the relationship between root forks and branch angle of Reaumuria songarica in response to slope aspects in the northwest of China. Methods The study site was located in desert grasslands on the northern slope of Qilian Mountains, Gansu Province, China. Survey and sampling were carried out along 20 belt transects. It were set up on sites of four dif- ferent slope aspects at intervals of 30 m vertically from elevation 1940 m of the study area moving upward, 6 plots were set up flatly on site of each belt transect at intervals of 20 m. A handheld GPS was used to record lon- gitude, latitude and altitude of each plot. ArcGIS was used to set up digital elevation model to extract the informa- tion of elevation, aspect, and slope for each plot. The traits of plant communities were investigated and 1 individ- ual's samplings of R. songarica were used to measure the root forks, root length and root branch angle in labora- tory in each plot, and biomass of different organs was measured after being dried at 80 °C in an oven. The 120 plots were categorized into groups of south, west, east, and north aspects of slopes, and the linear regression analysis was then used to examine the trade-off relationship between root forks and branch angle in various groups. Important findings The results showed that with the slope aspect turned from south, west, east to north, the density, cover, height, above biomass and soil moisture content of the plant community displayed a pattern of ini- tial increase, while the height, root-shoot ratio, root branch angle of R. songarica displayed a pattern of initial de- crease, and the density, specific root length, root forks increase. The number of root forks was negatively associ- ated with the branch angle, but the relationship varied along the aspect gradient (p < 0.05). There was a highly

Changing climate response in near-treeline bristlecone pine with elevation and aspect

In the White Mountains of California, eight bristlecone pine (Pinus longaeva) tree-ring width chronologies were developed from trees at upper treeline and just below upper treeline along North- and South-facing elevational transects from treeline to ~90 m below. There is evidence for a climate-response threshold between approximately 60–80 vertical m below treeline, above which trees have shown a positive growth-response to temperature and below which they do not. Chronologies from 80 m or more below treeline show a change in climate response and do not correlate strongly with temperature-sensitive chronologies developed from trees growing at upper treeline. Rather, they more closely resemble lower elevation precipitation-sensitive chronologies. At the highest sites, trees on South-facing slopes grow faster than trees on North-facing slopes. High growth rates in the treeline South-facing trees have declined since the mid-1990s. This suggests the possibility that the climate-response of the highest South-facing trees may have changed and that temperature may no longer be the main limiting factor for growth on the South aspect. These results indicate that increasing warmth may lead to a divergence between tree growth and temperature at previously temperature-limited sites.

Effects of tree species and topography on fine and small root decomposition rates of three common tree species (Alnus glutinosa, Picea orientalis and Pinus sylvestris) in Turkey

Fine and small roots of trees are an important part of the terrestrial carbon (C) cycle because they comprise a large fraction of annual net primary production and as ephemeral tissues they are returned to the soil on relatively short time scales. Their decomposition in soil can play an essential role for nutrient cycling and organic matter turnover within ecosystems that are important determinants of plant productivity and ecosystem carbon (C) storage. However, the processes and factors influencing the fine-root decomposition rates in forest ecosystems has been studied less than that of litter shed from the above ground parts of trees. In the present study, we therefore investigated the effects of tree species, topography and soil depth on the decomposition rates of fine and small roots using alder (Alnus glutinosa L.), Oriental spruce (Picea orientalis L.) and pine (Pinus sylvestris L.) tree species. The root samples collected from two aspects (north and south) and two altitudes (900m and 1260) on each aspect, and were placed into 0–10cm and 10–20cm of soil depth. Standard root samples were also placed on the same sites in order to evaluate the effects of microclimate on the root decomposition rates. Alder roots showed the highest decomposition rates, followed by pine and Oriental spruce roots. For each tree species, the root samples placed on south aspect and at lower slope on each aspect decayed faster than that on north aspect and at higher slope. The root decomposition rates decreased with increasing root thickness and soil depth. Among the tree species, initial root litter quality (especially C:N ratio) played an important role on their decomposition rates. In addition to litter quality factor, air temperature in open area and under the stands affected decomposition rates of the standard root samples.

Elevation, slope aspect and integrated nutrient management effects on crop productivity and soil quality in North-west Himalayas, India

On farm bio-resource recycling has been given greater emphasis with the introduction of conservation agriculture specifically withclimate change scenarios in the mid-hills of the north-west Himalaya region (NWHR). Under this changing scenario, elevation, slope aspect and integrated nutrient management (INM) may affect significantly soil quality and crop productivity. A study was conducted during 2009–2010 to 2010–2011 at the Ashti watershed of NWHR in a rainfed condition to examine the influence of elevation, slope aspect and integrated nutrient management (INM) on soil resource and crop productivity. Two years of farm demonstration trials indicated that crop productivity and soil quality is significantly affected by elevation, slope aspect and INM. Results showed that wheat equivalent yield (WEY) of improved technology increased crop productivity by ∼20%–37% compared to the conventional system. Intercropping of maize with cowpea and soybean enhanced yield by another 8%–17%. North aspect and higher elevation increased crop productivity by 15%–25% compared to south aspect and low elevation (except paddy). Intercropping of maize with cowpea and soybean enhanced yield by another 8%–15%. Irrespective of slope, elevation and cropping system, the WEY increased by ∼30% in this region due to INM technology. The influence of elevation, slope aspect and INM significantly affected soil resources (SQI) and soil carbon change (SCC). SCC is significantly correlated with SQI for conventional (R2 = 0.65*), INM technology (R2 = 0.81*) and for both technologies (R2 = 0.73*). It is recommended that at higher elevation. (except for paddy soils) with a north facing slope, INM is recommended for higher crop productivity; conservation of soil resources is recommended for the mid hills of NWHR; and single values of SCC are appropriate as a SQI for this region.

Effects of red deer exclusion on the corticolous and terricolous cryptogam community of Atlantic woodland

Deer exclosures are often used to encourage woodland regeneration in the Scottish Highlands. However, dense saplinggrowth,intheabsenceofreddeer(Cervus elaphus),withinexclosurescouldposeathreattointernationally important lichen communities on mature oaks in open woodland. Cryptogam communities associated with the lower trunks of oak trees (Quercus × rosacea Bechst.) were compared from several blocks, inside and outside three exclosures, in Atlantic oak woodland north of Loch Maree, Wester Ross, Scotland. Epiphyte data were collected from three different height zones on both the north and south aspects of oak trees. Terrestrial cryptogam communities, sapling density, shrub cover and height were also compared. Data were analysed using linear mixed effects models. Mean Lobarion lichen cover and species richness was significantly lower on both aspects of oak trees within exclosures in quadrats from more than one zone. Sapling density, dwarf-shrub height and coverweresignificantlygreaterwithinexclosures.Terrestrialcryptogamdiversityandspeciesrichnessweresignificantly lower inside exclosures. The data suggest that increased shading by saplings around mature oaks in open woodland has had a detrimental effect on Lobarion lichens after 17‐22 years of exclosure. Alternative strategies for encouraging woodland regeneration without harming the Lobarion lichen community are discussed.

Predicting the resting sites of Eurygaster integriceps Put. (Hemiptera: Scutelleridae) using a geographic information system

Sunn pest Eurygaster integriceps Puton is the most destructive insect pest of wheat and barley in Iran. This pest is a univoltine insect that feeds and reproduces in the fields for only 2–3 months of the year and spends the rest of the year in resting sites. In Sunn pest management programs, the pest populations in the fields are estimated by monitoring populations in the resting sites. The objectives of this study were to find variables associated with Sunn pest resting sites, using statistical tools and a geographic information system; and predict resting sites using these variables. This study was conducted in East Azarbaijan province of Iran. Six hundred points were sampled during a three year study. The twelve topographic and environmental variables including elevation, relative elevation, slope, aspect, north–south aspect data, landshape, slope steepness, slope configuration, topographic position, soil moisture potential, sun index and normalized difference vegetation index (NDVI) were examined. The models and variables were evaluated using corrected Akaike’s information criterion (AICC). NDVI, relative elevation, elevation, topographic position, soil moisture potential, north–south aspect and aspect which had high AICC weight were used in the prediction model. The resting sites of Sunn pest in Marand County of East Azarbaijan province was predicted using the model obtained with the purpose of testing it. Comparing the predicted resting sites with the actual ones revealed that large parts of the predicted areas in south were in accordance with the actual resting sites in Marand. The generated prediction map for E. integriceps can have several applications. Targeted monitoring and management of overwintering populations of Sunn pest using this map will save time and money.

Professional accounting education programmes in South Africa and India

Purpose – The purpose of this paper is to provide a contextual analysis of the professional accounting education programmes in South Africa and India by benchmarking both programmes to the International Education Standards (IESs) of the International Federation of Accountants (IFAC). Design/methodology/approach – The research methodology is a qualitative archival approach extracting information from secondary data (Statements of Membership Obligations’ compliance questionnaires available on the IFAC web site and information from the web sites of the relevant professional accountancy bodies). Findings – With regards to the IESs, the study found that both countries comply with the standards, although important differences occur. In South Africa, most of the education takes place during the university phase; and while both countries cover the content requirements, India covers the acquisition of professional skills more formally; ethics is taught and examined in both countries; both countries require a three year training contract; both countries have a final examination but the content of the examinations are different; and South Africa requires more continuous professional development than India. These findings, when related to India's and South Africa's relative positions on certain of the Global Competitiveness Indices may indicate that India could learn from the South African accountancy education model in order to strengthen the Indian position with regards to auditing and reporting standards. Research limitations/implications – A limitation of the study is that it did not investigate the quality of the relative education programmes and it benchmarks both programmes at a single point in time. Practical implications – India could strengthen its accounting profession by implementing some of the South African aspects of its education model. South African could consider adopting the flexibility in the entry requirements in the Indian education model in order to increase the number of accountants in South Africa. These findings may also be useful to other developing countries to identify practices which could be adopted if suitable in their respective countries. Originality/value – The study is original as accountancy education programmes in India and South Africa have not been contrasted before. In view of their similar colonial background and the fact that both countries are major economic and political forces in their respective regions, the value of this study is that it provides useful and relevant information to India, South Africa and other countries with similar economic and social backgrounds.

Estimation of net shortwave radiation flux of western Himalayan snow cover during clear sky days using remote sensing and meteorological data

The aim of this letter is to estimate incoming and net shortwave radiation fluxes of large snow-covered area of western Himalaya and to evaluate the results with in situ observations. Radiation fluxes are estimated at spatial levels using remote sensing data from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor and Shuttle Radar Topographic Mission (SRTM) digital elevation model (DEM), supplemented with sparse field data obtained from automatic weather stations (AWSs). Snow cover albedo has been estimated from MODIS data using narrowband to broadband conversion method for clear sky days. Geospatial maps of air temperature (Ta) and relative humidity (RH) have been generated for the study area using AWS recorded Ta/RH and DEM. Parameterization techniques have been used for estimating incoming and net shortwave radiation fluxes, which have been validated from in situ AWS observations. The root mean square error (RMSE) in estimation of incoming shortwave radiation flux and net shortwave radiation flux has been found to be 75 and 84.9 W m−2, respectively. Further, the higher radiation fluxes have been observed on south aspect slopes than those observed on north aspect slopes.

Early performance of oversown pasture mixtures on non-cultivable hill country at four geo-climatically different sites

Abstract A trial was conducted on non-cultivable hill country (&gt;20o slope) at four sites to determine the effect of seed mixture (grass+legume+herb vs legume) and sowing time (spring vs autumn) on plant establishment. Sites were in Canterbury (1 site), Hawke's Bay (2) and Waikato (1) on north and south aspects and differed predominantly in climate. In the first spring after sowing (12 months after spring sowing; 6 months after autumn sowing), sown legume and total sown species contributions (% of total dry matter (DM)) were: greater in the grass+legume+herb than legume mixtures; greater when sown in spring than autumn (15 vs 7% for sown legumes and 41 vs 21% for total sown species); and similar on north and south aspects. Sown grass contribution was greater from autumn than spring sowing (79 vs 65%) while sown herb contribution was greater from spring than autumn sowing (15 vs 1%), but both were similar across aspects. The contribution of unsown species was high, averaging 59% in springsown swards and 78% in autumn-sown swards. There was no effect of seed mixture or sowing time on DM production in spring (September-November; averaging 2660 kg DM/ha in Canterbury and 5080 kg DM/ha at a Hawke's Bay summer-moist site). However, DM production was greater in spring- than autumn-sown swards in summer at both sites (December-February; Canterbury: 1980 vs 1520 kg DM/ha; Hawke's Bay: 3980 vs 2670 kg DM/ha). In a wet year, broadcasting seed during spring rather than autumn is likely to result in the highest early DM production and contribution of sown species (sown grasses, legumes and herbs) in the sward. The high unsown species contribution emphasises the importance of dealing with the seed bank before establishment, especially when sowing in autumn. Keywords: seed mixture; pasture establishment; botanical composition; unsown species ingress; pasture improvement.

Influence of landscape attributes on soil-plant inter-relationships

Topography influences soil properties and inter-relationships with plants. While precision agriculture emanates from precise use of information, consideration of landscape attributes is essential in crop management. Generalized linear model (GLM) indicated that landscape, slope classes and their interaction significantly described 36% of variability in effective soil volume (ESV). Factorial model describeda significant 15% of growth of Hevea brasiliensis contributed by these aspects. Rubber yield was in order of East > West > North > South and a significant influence of aspect, slope and their interaction (R2=0.539). ANOVA depicted highly significant effects of aspects, slope class and their interaction on soil moisture with ESV as a covariate (R2 = 0.986). The impact of ESV on soil moisture was highlighted by negative correlation with gravel content (r= -0.373**, significant at 1% level). GLM identified an equation; latex yield= 1745.3** – 15.75 slope** – 461.9 North aspect** – 233.2 West aspect* – 364.9 South aspect** (*indicates significance at 5% level). Slope significantly and negatively influenced yield. Slope being constant, average yield decreased by 461.9 mL due to north with reference to east (equal to 1745.3–461.9=1283.4 mL). Similarly, decrease in yield on South (by 364.9mL) and West (233.2) was also predicted. This study may form a basis for further research on microclimate and yield relationships as governed by aspect and slope to achieve precision farming.

山地城市坡向对地表温度的影响——以重庆市主城区为例

In mountain areas,land surface temperature( LST) is a key parameter in the surface energy budget and is an outcome of a complex interplay of topography,incoming radiation,atmospheric processes,soil moisture,land covers and vegetation types. One important factor that controls LST is topography. Slope and aspect are generally considered as important parameters in ecology as they directly influence the potential radiation and heat load in small scale. In built-up areas in mountain city,where land use /cover is completely dominated by human activities that exert a great influence on the local climate,biogeochemical circle and landscape diversity,LST is influenced not only by topology but also by human activities. In order to reveal the influence of aspect on LST,central area of Chongqing city,a typical mountain city,has been chosen as an example. Land surface temperatures( LSTs) derived from Landsat TM images were extracted by aspect using spatial analysis function in ArcGIS,and were analyzed using analysis of variance( ANOVA) in SPSS. Firstly,the scatter diagram of aspect and LST,that were extracted for each pixel,shows neither simple linear nor nonlinear relationships. Secondly,the aspect is divided into different number of classes,namely,four classes( every 90°),eight classes( every 45°),16 classes( every 22. 5°),32 classes( every 11. 25°),64 classes( every 5. 625°),128 classes( every 2.8125°) and 360 classes( every 1°). The results show that LSTs in the southeast aspect and the south aspect are higher than other aspects,whilst LSTs in the northwest aspect and the north aspect are lower. Although aspect is an important factor influencing earth's surface energy received from the sun radiation,using finer resolution in aspect makes nosignificant difference from using coarser resolution. Among all class divisions,when the aspect is divided into 8 classes,the average LSTs in each aspect have the most significant differences. The average LST of each aspect is positively correlated to its area proportion in the study area. The average LSTs in each land cover /use are significantly different,however,the average LST in each aspect class is not significantly different in the same land cover /use type. This implies that the LST distribution in city is mainly caused by urban construction and human activities,roughly corresponding to different types of land cover /use. Comparing to strong environmental effects resulted from intensive and large-scale urban construction activities,the influence of aspect on LST is relatively weak. In mountain city,urban construction activities massively transform original natural topography into artificial terraces and the urban construction size is much greater than the size of hill reserved inside the city,hence it is difficult to identify aspect effect on LST. The most likely reason for this is that the differences of light condition,soil moisture,precipitation and wind velocity result from aspect are disguised or offset by intensive human activities.

QUANTITATIVE CHARACTERS OF VEGETATATION COVER GROWN AT OVERLOOKING ASPECTS ON ASHAWA RESORT AT NORTHERN IRAQ.

This study was conducted at Ashawa resort in northern Iraq. including quantitative characters of vegetation grown in four aspect surrounding Ashawa resort with two elevation.The studied characters were (covering, relative covering, density, relative density, wet and dry weight, dry mater, plant height, frequency, relative frequency, Importance value, composition percentage).The results of grasses and herbs showed that the first level gave significantly a higher values of the traits (covering, density, wet and dry weight, grasses%, legumes%, richness, Shannon index, simpson index, homogeneity and carrying capacity) than the second level, while the second level of trees and shrubs gave significantly a higher values of the traits (covering, density, wet and dry weight, Shannon index, simpson index and homogeneity). The east aspect was significantly difference in the characters of grasses and herbs (covering, wet and dry weight, other herbs and carrying capacity), while the south aspect was significantly difference in (density and legumes%), no significant difference between north and west aspect in (richness, Shannon index, simpson index and homogeneity) was shown. As for trees and shrubs, the east aspect was significantly superiority of these qualities (density, richness. Shannon’s and Simpson’s diversity indices). The north aspect was superiority of these characteras (covering and homogeneity), while the south aspect was significantly superiority from the other aspects in (wet and dry weight). Through this study of the general covering it was shown that there were significant differences between aspects and elevations.

Soil water repellency in Mediterranean rangelands under contrasted climatic, slope and patch conditions in southern Spain

Abstract This study evaluates the spatial and temporal variability in soil water repellency (SWR) in two Mediterranean rangelands (with similar tree and shrub species) and its relationships to different eco-geomorphologic variables (climate, aspect, soil cover and some soil properties). Every month from October 2008 to May 2009 (rainy season), soil moisture and SWR was measured in field conditions by means of gravimetric method and Water Drop Penetration Test, respectively. Also, disturbed and undisturbed soil samples were taken to analyze some soil properties: bulk density, texture, organic matter, pH and electrical conductivity. The entire tests were performed in north and south aspect hillslopes and beneath shrub and bare soil in every of them. The results indicated that: i) climatic conditions seem to be more transcendent than the vegetal species for explaining the variability in SWR; ii) thus, SWR appears to be controlled by the antecedent rainfall and soil moisture; iii) more severe SWR were observed in patches characterized by sandier soils and/or higher organic matter contents; and iv) the factor ‘hillslope aspect’ was not found so crucial as it was expected.

Efectos de la vegetación y orientación de la ladera en perfiles de humedad en el suelo de un ambiente semiárido del interior de España

This study has investigated the evolution of soil water content profiles on bare soil as well as under plant coverage. It was undertaken in two topographically contrasting slopes (north and south aspect) and at three depths. The results indicate spatial differences and a temporal diachrony between the processes of evaporation (in bare soil) and evapo-transpiration (under plant coverage). The slope aspect is the majar determining factor in soil water evolution. There were persistant differences between the south aspect and the north aspect over the periods studied (p0.05), while the plant coverage occasionally induced significant differences over the bare soil (p0.05) in some of the depths analyzed.

Variaciones espaciales de la textura en las laderas de exposición topográfica contrastada en el semiárido aragonés

Textural sediment variations between top-bottom slope position have been studied in a semiarid environment (La Violada, Huesca, NE Spain). Differences are observed according slope aspect. In south aspect the covariability between coarse sand and fine sand with distance from divide is positive (&gt;0.95), and negative with slope angle (&gt;0.95). The same relationship is found with coarse silt, but with negative value. There are not been observed significant relationships between fine silt and clay subfraction witb distance and slope value. In north aspect slope tbere are not found any relationships between sand, silt and clay fraction with distance and slope value. Results are discussed according to erosion processes.