RELIEF ASPECTS IN SLOVENIA EKSPOZICIJE POVRŠJA V SLOVENIJI DRAGO PERKO Abstract l/DC 911.3:312 (497.12) Relief aspects in Slovenia Ridges oriented west-east and northwest-southeast significantly influence the proportion of individual relief aspects in Slovenia. Aspect is an important natural landscape element which has a statistically significant correlation with the proportion of forest, the density of settlements, and the density of population. Key words: Slovenia, macroregions of Slovenia, gcomorphology, demography, relief aspect, forest, settlements, population, digital terrain model, geographical information system. Izvleček UDK 911.3:312(497.12) Ekspozicije površja v Sloveniji Deleži površin posameznih ekspozicij so odvisni predvsem od splošne slemenitosti površja v Sloveniji. Med ckspozicijo ter deležem gozda, gostoto naselij in gostoto prebivalstva je statistično pomembna povezanost. Ključne besede: Slovenija, makroregije Slovenije, geomorfologija. demogeografija, ekspozicije reliefa, gozd. naselja, prebivalstvo, digitalni model reliefa, geografski informacijski sistem. Addness - Naslov Dr. Drago Perko Znanstvenoraziskovalni center SAZIJ Geografski inStilut Antona Melika Gosposka ulica 13 61000 Ljubljana Slovenija 1. INTRODUCTION Relief aspect, which is characteristic of every uneven surface, is the azimuth of direction of the slope in the relief, that is, the angle between due north and the direction of viewing from higher to lower height above sea level. It can also be determined as the direction toward which the relief is turned . Relief aspect therefore indicates which side of the sky the surface is turned to. It is usually expressed by an azimuth sign between 0" and 360" clockwise. Relief aspect is an important natural landscape element because it influences the amount of solar energy received, an important element in gcomorphological, hydrological, pedological, biological, and other natural processes, and at the same time an important factor in settling and diverse other human activities (Gams 1988). Sometimes, it can have decisive importance, for example, in the distribution of vineyards, forests, settlements, ski slopes, and the like. Incline has an important role in relief aspccts. Between relief aspect and incline there is no direct correlation, because the coefficient of their correlation is not statistically significant, although an increase in incline causes an increase in relief aspect and its influence on other landscape elements. Aspect can be combined in classes named after the sides of the sky. Combining into four 90" wide classes named after four basic sides of the sky is the simplest solution: north aspects have an azimuth between 0° and 45° and 315® and 360°, east aspects between 45" and 135°, south aspects between 135" and 225°, and west aspects between 225° and 315°. Combining into eight 45° wide classes named after the four basic and four side sides of the sky is more accurate: north aspccts have their azimuth between 0.0® and 22.5" and 337.5° and 360.0", northeast aspccts between 22.5" and 67.5", cast aspccts between 67.5° and 112.5°, southeast aspccts between 112.5" and 157.5® , south aspccts between 157.5" and 202.5®, southeast between 202.5" and 247.5®, west aspects between 247.5" and 292.5® and northwest aspects between 292.5® and 337.5®. In some cases, aspects can only be divided into two 180" wide classes: north aspects (between 0" and 90" and 270" and 360") and south aspects (between 90" and 270°) or into east aspects (between 0" and 180") and west aspccts (between 180" and 360"). 2. METHODOLOGY We determined aspects with the help of a digital terrain model and the geographical information system, enabling a relatively simple and quick definition of aspects even for larger areas (Perko 1993). Aspects in Slovenia were defined with the help of a hundred-meter digital terrain model (Geodesic Officc of Slovenia, 1991) containing heights above sea level of the corners of squares in a grid, each square having a base line 100 m long and an area of 10.000 nr. i.e. one hectare. On the relief layer we placed centroids of settlement (Geodesic Office, 1992), that is, points representing condensed cores of settlement to which we attached population data. Because of the methodological problems involved in defining centroids of settlement for large areas of settlement such as scattered settlements or settlements consisting of secluded farmsteads (Kokra, Strojna, etc.) and for large settlement areas such as Ljubljana and Maribor. the distribution of settlements and population according to the aspects and the corresponding indexes should be regarded as estimations, which due to the very large amount of data employed arc representative enough and reflect a certain legitimacy (Perko 1992 B). In the framework of the Geographical Information System of Slovenia (Perko 1991) developed at the Anton Melik Geographical Institute primarily for the needs of regional geographical studies and studies of correlations betw een terrain phenomena (Perko 1992 A), we calculated aspects for 2,025,652 hectare squares with the help of IDR/S/ software (Clark University 1991) which calculated the aspect of each square on the basis of changes in its heights above sea level as well as those of each of eight neighbouring squares. Some 3.4 % of surface in Slovenia has an incline less than 0.5" and for the purposes of this paper such surfaces are treated as level and without aspect. We expected the remaining surface to be equally divided among aspect classes, but in fact, differences arc noticeable. 3. FINDINGS Ifaspects are divided only into north (azimuth between 0 and 90° and 270 and 360") and south position (azimuth between 90 and 270"), a good half of Slovenia's surface has a south position, and only a good two fifths has a north position. Or in another words. 18 % more surface area in Slovenia faces south than north. If aspecLs arc divided into east (azimuth between 0 and 180") and west (azimuth between 180 and 360") positions, the difference is smaller: 5 % more surfacc faces cast than west. Differences also exist in average incline. North positions have an average incline of 14.3° and south positions of 13.0", the difference being 10 %. West positions have average incline of 13.8° and east positions of 13.4 %, the difference being smaller than 3 %. The differences between average height above sea level in north and south positions is nine meters, and between east and west positions five meters. In Picture I, south aspects arc coloured black, and in Picture 2. east aspects arc coloured black. This is actually a very simple example of shading relief with two basic colours Figure 3: Aspects multiplied by inclines (2 classes, black-white). Slika 3: Ekspozicije, poudarjene z nakloni (2 razreda, črnobelo). without grey halftones: in Picture 1 light comes from the north, and in Picture 2 from the west. Some basic relief characteristics can be seen clearly in the pictures: main faults, ridges, diverse surfaces, etc. If we multiply aspects by inclines, we get Picture 3, in which areas with low values (north aspects and small inclines) are coloured white and areas with high values (south aspects and large inclines) arc coloured black. Such a presentation of the relief is even more realistic if white is used to present only the lowest values and black to present the highest values while the values between arc presented by grey halftones (Radovan 1992), (Picture 4). Some faults can be clearly seen (for example, the Sava and Idrija fault), as well as individual overlaps (for example the south edge of Trnovski gozd, Nanos and HruSica) and the larger and more distinct valleys (for example the Sava Valley between the Julian Alps and the Karavankc Mountains, between the Bohinj and Bled lakes and through the Posavsko hills, the Drava Valley between Pohorje and Kozjak, the Kolpa Valley, and C'epovanski dol); furthermore, the ratio of broken to unbroken landscapes is very apparent. If we divide the aspccts into north (azimuth between 0" and 45" and 315" and 360°), east (azimuth between 45" and 135°), west (azimuth between 135° and 225°), and south (azimuth between 225° and 315°) positions, a good quarter of Slovenia's surface has a south position, 23 % each for north and east positions, and one percent less for the smallest, west position. In other words, 21 % more surface in Slovenia faces south than north. 22 % more surface south than east, and 27 % more terrain faces south than west. North positions have the largest average incline (14.T), followed by west (13.8°), east (13.5°), and south (13.1°) positions. The difference between the average incline of north and south positions is 8 %. West positions have the highest average height above sea level (571 m), followed by east (569 m). north (566 m), and south (567 m) positions. The difference between average height above sea level between north and south positions is 9 m, and between cast and west, 5 m. Let us have a more exact look at the division of aspccts into eight classes: the four basic classes (north, south, east, and west) and the four side classes (northeast, northwest, southeast, and southwest). 3.1. RELIEF When we subtract completely level surface, that is, 3 .4 % of Slovenia's surface (all the flat land with average inclines between 0.0° and 1.9" totals 14.3 %), 12.1 % of the surface remains on average for each of the eight aspects. Actually, there arc more south positions, 14.7 %, which is one fifth higher than the average theoretical value, and almost two thirds more than northwest positions which total only 9.2 % of Slovenia's surface, a quarter less than the average value. Above average values arc seen in southwest, northeast, and east positions, while figures for west, north, and southeast positions are below average This can be explained by the main ridges which divide division of Slovenia in east-west and northwest-southeast directions, because the surfaces of individual aspects also depend on the surfaces of the ridges. Theoretically, north and south positions should dominate on west-east ridges and cast and west positions should dominate on north-south ridges. Thus there are more south and north positions in the alpine world (Tabic 2) where south and north positions represent almost one third of all areas while cast and west positions only represent one fifth of all areas; in Dinaric areas where ridges run northwest-southeast, there are more northeast and southwest positions and northeast and southwest positions represent one third and northwest and southeast positions less than one fifth of all the areas. That there are a larger number of south aspects than north aspects can be explained by the fact that along Slovenia's northern border, the majority of north slopes are in Austria and of south slopes in Slovenia. The prevalence of east aspects over west aspects can be explained by similar conditions on the border with Italy, where most west slopes belong to Italy and east slopes to Slovenia. On the eastern and southern border towards Croatia, there is more level and hilly relief, so that the slopes are less steep and more extended and therefore cannot replace the missing west slopes in Italy and north slopes in Austria. This can be also attributed to the fact that the borders with Austria and Italy run roughly along crests and ridges while the border with Croatia mostly runs along waterways and thus valleys. Another possible explanation is that aspects with large areas have smaller inclines and vice versa. Let us pose the basic hypothesis that areas of individual aspects and their average incline arc in correlation and the null hypothesis that they are not in correlation or that all the existing differences are accidental. The coefficient of correlation between area and average incline is -0.6632, which is in the absolute sense a high coefficient the negative sign indicating that with diminishing inclines, the areas increase. However, the t-test coefficient of correlation indicates that the calculated t, which has a value of2.1709, is smaller than the critical value of t, which at 99.9 % validity has a value of 5.959. Therefore, with 99.9 % probability we can reject the basic hypothesis on correlation and accept the null hypothesis that there is no significant statistically significant correlation between areas of individual aspects and average incline, and thus we cannot say that aspects with smaller average incline have larger areas. If we compare the distribution of relief aspects according to macrorcgions in Slovenia (Gams, Kladnik, and Orožen Adamič 1994), the discrepancy is even larger. In the Alpine region, the ratio between the proportion of south positions, which are in majority, and west positions, which are in minority, is almost 2 to 1. On the floor of the Ljubljana Basin, which has the largest number of south positions and the smallest number of northwest positions, the ratio is more than 4 to 1. In the subpannonian area, which has the largest number of south positions and the smallest number of northwest positions, the ratio is 2 to 1. In the Dinaric area, which has the largest number of southwest positions and the smallest number of northwest positions, the ratio is less than 2 to 1. in the submediterranean area, which has the largest number of southwest positions and the smallest number of west positions, the ratio is 2.5 to 1 (Table 2). The smallest and largest proportions of any aspect are on the floor of the Ljubljana Basin where northwest positions comprise only 5.7 % and south positions as much as 23.7 % (Table 2). In other macrorcgions the differences are smaller. Table I : Areas of individual aspects with average incline and average height above sea level. Preglednica I: Površine posameznih ekspozicij s povprečnim naklonom in povprečno nadmorsko viiino. Surface Proportion Average Average height in hectares of surface incline in metres in% in degrees above sea level PovrSina Delež Povprečni Povprečna v ha površin naklon višina v% v stop. v m Division into Delitev na two classes dva razreda North Sever 897490 44.30 14.25 573,49 South Jug 1059964 52,33 13,04 564,00 Level Ravno 68198 3,37 0,07 222,80 Total Skupaj 2025652 100,00 13,13 556,63 Last Vzhod 1000588 49,39 13,44 566,09 West Zahod 956866 47,24 13,75 570,71 Level Ravno 68198 3,37 0,07 222,80 Total Skupaj 2025652 100,00 13,13 556,63 Division into Delitev na four classes Štiri razred North Sever 472494 23,33 14,14 566,43 Last Vzhod 467263 23,07 13,51 568,67 West Zahod 448175 22,12 13,77 571,49 South Jug 569522 28,11 13,08 566,91 Level Ravno 68198 3,37 0,07 222,80 Total Skupaj 2025652 100,00 13,13 556,63 Division into Delitev na eight classes osem razredo North Sever 233965 11,55 14,45 571,09 Northeast Severovzhod 257741 12,72 13,84 560,96 Northwest Severozahod 185725 9,17 15,06 592,89 East Vzhod 247720 12,23 12,63 549,32 West Zahod 217104 10,72 13,79 574,81 Southeast Jugovzhod 240799 11,89 12,95 570,76 Southwest Jugozahod 277326 13,69 13,47 566,99 South Jug 297074 14,67 13,07 567,84 Level Ravno 68198 3,37 0,07 222,80 Total Skupaj 2025652 100,00 13,13 556,63 Table 2: Proportion of surfaces of individual aspects by macmregions of Slovenia (omitting level reliefs). Preglednica 2: Deleži povriin posameznih ekspozlcij po makroregijah Slovenije (brez ravnega sveta). N NE NW E W SE SW S Total Macnmgxm* Makroregijc S SV SZ V Z JV JZ J Skupaj Alpine Alpski svet Iti 10,1 10.3 11,2 9.9 14.2 12,9 114 100,0 Weslwrn subalpine Zahodni predalpski svet ■ 3.0 13.1 10.5 12.0 10.6 12.0 13,3 14,K 100,0 Eastern subalpine V/hodni predalpski svel IM 12.2 10.6 11.7 10.2 12.7 12.1 15.9 100,0 Ljubljana Rann door Dno Ljubljanske kotline 7.9 *,9 5.7 11.7 94 ■ 6.9 16,0 23.7 100.0 Subalpinc-iubpamonian PrtdalpikMubpanonski svet 10,4 11,5 «.3 13.4 10,6 14.4 14,7 16.7 IOO.O Suhalpine-Dinonc Predalpsio-dinanki svel 12.6 16,1 14.6 M 134 12,7 14,0 100,0 Subalpine-Liuoral Preiialpsko-primorski svel 10,1 11,1 16.4 9,4 II.) 9.7 13,0 10,S 100,0 Subpannunian Subpanwnfci svel 10.4 13,0 7.6 16.7 9.9 14.7 11.1 15,9 100,0 Subponnonian-Oinaric Subpononsko-dinanki svel ■44 15,1 13,2 11.7 113 11,0 12,3 11.4 100,0 Dinaric Dinarski svel 11.0 16.3 9.0 13.1 13.1 9J 16,6 11.7 100,0 Dinaric-Litloral Dinarsko-primorski svel 12.3 13.5 I0..1 11.5 12.3 10,i 16,3 13,5 100,0 Lilian! Primorski svel 14.0 I2J 10,6 7.5 13.4 <.4 19,0 14.7 100,0 Sto» tua Slovenija 119 13 J 9.5 12.6 ll.l I2J 14,2 154 100,0 3.2. AVERAGE INCLINES The average incline for Slovenia is 13.1 0 Among aspects, northwest positions have the highest average incline at 15.1®, followed by north positions with 14.5®. The lowest average inclines belong to southeast positions with 13.0° and cast positions with 12.6®. The difference between highest and lowest average incline is 19®. East, southeast, and south positions have average inclines below the average for Slovenia. It is interesting how the proportions of individual aspects change according to incline. South or southwest positions dominate for reliefs with inclines between 0° and 6n, southwest positions dominate up to 20°, south positions again dominate up to 50°, northwest positions dominate between 50° and 70", and north positions dominate above 70°. Slopes of SDl •C Vi* " ^—-— JUO II w« on M"» SDt XX ttuomaao juoozmgo ■ ' • on " OH *«»» XX jnm ^žMiaiii 0 II »"O " on " XI X* vsa» zmoo / ■-:--—"-' • ' • n « 0 H Figure 5: Changing of surface proportions of individual aspects according to increasing incline. Slika 5: Spreminjanje deleža površin jxtsameznih ekspozicij z rastjo naklona. 30" incline, have the least northwest positions, slopes between 30" and 50" have the least west positions, slopes between 50" and 60" have the least northeast positions, and slopes above 60" have the least southwest positions. How the proportions of reliefs of individual aspects change according to increasing incline is seen in Picture 5. Roughly speaking, the proportion of north and northwest positions increases with the increase of incline while the proportion of south and southwest positions declines, and the remaining positions arc represented equally according to all inclines. Table 3: Proportions of aspects according to incline classes with various lowest limits. Preglednica 3: Deleii ekspozicij po naklonskih razredih z razlicno spodnjo mejo. Degrees N NE NW E W SE SW S Level Total Stopinje S SV SZ V Z JV JZ J Ravno Skupaj 0-89 11,55 12,72 9.17 12.23 10,72 11,89 13,69 14,67 3,37 100,00 2-89 12,20 13,47 10,03 12,12 11,48 11.75 14,50 14,42 0.03 100,00 6-89 12.45 13,57 10,22 12,03 11,48 11,58 14,39 14,28 0.00 100,00 12-89 12.95 13,64 10,47 11.64 11,37 11,43 14,14 14,36 0,00 100,00 20-89 13,15 13,43 10,80 11.35 10,88 11,80 13,62 14,97 0.00 100,00 30-89 12,74 12,59 11,19 11,00 10,40 12.52 13,45 16.11 0.00 100.00 45-< 14,25 10,54 17,20 10,50 10,93 12.70 10,55 13,33 0,00 100,00 3.3. AVERAGE HEIGHT ABOVE-SEA LEVEL Northwest positions have the highest height above sea level at 593 m. followed by west positions with 575 m. Southwest positions with 567 m and east positions with only 549 m have the lowest average heights above sea level The difference between the highest and lowest heights above sea level is only 5 %. Only northeast and east positions have their average heights above sea level below the average for Slovenia, which is 557 m. It is interesting that the proportion of individual aspects changes in hundred-meter height zones. South positions dominate in areas with heights above sea level between 0 and 400 m, southwest positions then dominate to 900 m, south positions again dominate to 1900 m, and mainly southeast and south positions dominate in higher areas. Elevations up to 1100 m have the least number of northwest positions, elevations between 1100 and 1700 m have the least west and northwest positions, elevations between 1700 and 2200 m have the least north positions, and higher elevations have the least west and southeast positions. The primary climax of level relief, that is, relief without aspect, is in the hundred-meter height zone between 100 and 200 m which includes some of the largest areas of level relief in Slovenia, for example, the Pomurska flatlands, the KrSko Basin, part of the Vipava Valley, and the northern section of Bela krajina. Secondary climaxes are found between 500 and 600 m, between 700 and 800 m, between 1200 and 1300 m where the largest number of Alpine plateaus lie (for example Jelovica, Pokljuka, and a part of Pohotje), and between Figure 6: Changing of surface proportions of individual aspects according to increasing height above sea level. Slika 6: Spreminjanje deleža površin posameznih ekspozicij z rastjo nadmorske višine. 1700 and 1800 m. This can be explained by the fact that in Slovenia's alpine area there arc flat areas at heights between 2300 and 2500 m, around 1800 m, around 1600 m, between 1500 and 1550 m, and between 1100 and 1200 m. In the Dinaric area, there arc flat areas between 1000 and 1500 m and in the subpannonian area even lower (Sifrer 1972). I low the proportion of areas of individual aspects changes with increasing height above sea level is shown in Picture 6. Roughly speaking, individual aspects arc equally represented in all the height zones and especially so in comparison with inclines. 3.4 ASPECTS AND FOREST The proportion of forest was determined on the basis ofthc digitalized 1 : 250.000 scale Natural and Potential Vegetation Map (Biology Institute ZRC SAZU). Most densely forested are northeast positions with 61.9 hectares of forest per square kilometer, followed by north positions with 61.7 hectares per square kilometer. In south positions forest covers 49.0 hectares per square kilometer of the relief, and in other positions between 50 and 60 hectares per square kilometer. The proportion of forest thus decreases from north to south aspects. On level relief, the density of forest is only 14.9 hectares per square kilometer. The ration of forested to unforested relief is 1 : 1.6 for northeast and north positions and almost I : 1 for south positions. There is a little more forested than unforested area in southwest positions, while in south positions, forest covers less than half of all areas. Of all the forested areas in Slovenia, 14.5 %arc found in northeast positions, 13.3 %in south positions, 13.2 % in north positions, 12.8 % each in east and southwest positions. 11.6 % in southeast positions. 10.8 % in west, 10.1 % in northwest positions, and less than one percent in level reliefs. The density of forest areas according to aspects is seen by the coefficient of concentration, which has a value between 0 and I. When the coefficient of concentration of a phenomenon is 1, this phenomenon is concentrated in just one class, in our case in just one aspect; when the value is 0. the phenomenon is equally represented in all classes without concentrated areas. In a landscape, the coefficient of concentration rarely has extreme values. The coefficient of concentration of forested areas according to aspects (including level relief) is 0.1217, a good firth higher than the concentration of areas of individual aspects. This suggests a definite correlation between aspect and proportion of forest. As we tried to establish a correlation between incline and relief aspect, we can also try to establish a correlation between aspect and proportion of forest. Our hypothesis is that the distribution of all reliefs according to aspect differs distinctly from the distribution of forest areas according to aspects, and the null hypothesis is that there are no differences. The hi-square value is 7814.5, which is substantially higher than the critical (border) 99.9 % valid hi-square value of 24.3 for the eight classes of aspects. Therefore, we may reject the null hypothesis and with 99.9 % probability accept the basic hypothesis that the distribution of reliefs and the distribution of forest differ in a statistically significant way. We can thus conclude that there is a definite correlation between aspect and proportion of forest. The coefficient of correlation between aspect and the distribution of forested and unforested areas that we calculated on the basis of a contingency table has a value of only 0.0946, which is small in the absolute sense; however, for the more than two million items of data we used in our calculations, the t-tcst of the coefficient showed that the corrélation is statistically significant, because the calculated t with value of 133 is substantially larger than the critical value of t with 99.9 % validity, proving a relatively strong correlation. Table 4: Pmportions of aspects in foresled and unforested areas. Preglednica 4: Deleii ekspozicif po gozdnih in negozdnih površinah. Surface PovrSina N NE NW E W SE SW s Level Total S SV sz V Z JV JZ 1 Ravno Skupaj Unforested Negozd 9.64 10.58 8.13 11.54 10,62 12.23 14.71 16.29 6,25 100.00 Forest Gozd 13,17 14,54 10,05 12.81 10,80 11.59 12,82 13.29 0,92 100.00 Slovenia Slovenija 11,55 12,72 9,17 12.23 10,72 ll,8i» 13,69 14,67 3.37 100.00 Table 5: Proportions of forest and unforested surfaces according to aspects. Preglednica 5: Deleii gozdnih in negozdnih površin fw eksfwzicijah. Surfaix PovrSina N NE NW E W SE sw S Level Toial S SV sz v Z JV JZ J Ravno Skupaj Unforested Negozd 38.28 38.13 40.65 43.29 •4M5 47.: i» 49.29 50.96 85.15 45.R7 Forest Gozd 61.72 61.87 59.35 56.71 54.55 52.80 50.71 49.04 14.85 54,13 Slovenia Slovenija 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100,00 3.5. ASPECTS AND SETTLEMENTS On north, northeast, and northwest positions, each settlement covers between 400 and 500 hectares, on east and west positions between 300 and 400, and on southeast, southwest, and south positions between 200 and 300 hectares. This means that the density of settlement increases from north to south aspects. On level relief, the density of settlement is the smallest, almost 700 hectares per settlement. The explanation for the lower density of settlement is primarily the fact that the land is either devoted largely to agriculture use or the area is flood prone, which would endanger settlements. In addition, settlements are larger on level relief. The coefficient of concentration (level relief omitted) for settlements is 0.1314. almost three times the coefficient of concentration for areas which have a value 0.0499. ("his points to the definite importance of aspect in the distribution of settlements; otherwise, both coefficients would be equal. The basic hypothesis is that the distribution of areas according to aspects is different from distribution of settlements according to aspects, and the null hypothesis is that it is not. The calculated hi-square has a value of 382.1 and the critical value of the hi-square is 24.3 at 99.9 % validity. So, we can accept basic hypothesis indicating a correlation between aspect and proportion of settlements with 99.9 % probability. 3. 6. ASPECTS AND POPULATION Population increased in all positions from 1869 to 1991. but in different ways. Between 1869 and 1931, population increased most in southeast positions where it increased almost by half, and least in northeast positions where it increased by only 7 %, meaning that population increased six times as much in southeast positions as in northeast positions. Understandably, population increased most conspicuously in level areas, by almost two thirds. Between 1931 and 1991, population increased most in east positions, by almost two thirds, and least again in northeast positions, by less than one fifth. In east positions, therefore, population increased almost four times as much as for northeast positions. At the same time, population in level positions increased by 150 %. Population increased only from 10.4 % to 10.9 % in east positions between 1869 ami 1991, in south positions from 20.2 % to 22.8 %. and in level relief more than four times, from 1.7% to 7.1 %. In 1991, a good half of the population lived in southeast, southwest, and south positions, and barely one fifth of the population of Slovenia lived in north, northeast, and northwest positions. In 1869, the most densely populated settlements were southwest positions with 77 people per square kilometer, and the most scarcely populated were northeast positions with 36 people per square kilometer, a 2 : 1 ratio. In 1991, southwest positions were the most densely populated and northeast positions the least, the ratio increasing to more than 3 : I. On level relief, the density of population was only 51 people per square kilometer in 1869, below the then average for Slovenia, which was 56 people per square kilometer; in 1991, the number was 205 people per square kilometer, four times more than in 1869 and twice more than the average density of population in Slovenia in 1991,97 people per square kilometer. The concentration of population according to aspects in 1991 was 0.1714, three and a half times more than the concentration of areas and one third more than the concentration of settlements. We can establish the significance of aspect by checking the basic hypothesis that the distribution of surfaces of individual aspects typically differs from the distribution of population, and the null hypothesis stating it docs not. For 1869, the calculated hi-square value is 75166.9. The critical value of the hi-square at 99.9% validity is only 24.3. We can therefore accept at 99.9 % probability the basic hypothesis stating that the distribution of surfaces typically differs from the distribution of population. From that year on, the hi-squarc increased constantly and in 1991 reached the value 223,237, almost ten thousand times more than the critical value. This means that distribution of population is strongly linked to aspect and that it constantly increased between 1869 and 1991. Table 6: Surfaces. settlements, and population in Slovenia according to aspects. Preglednica 6: Površine, naselja in število prebivalcev po razredih ekspozicije. Aspecl Razredi Area Number of Number oC population ekxpo/jcijc in hectors settlements 1869 1900 1931 1961 1971 1981 1991 Povrfina Število Število prebivalcev via naselij 1869 1900 1931 1961 1971 1981 1991 North Sever 234136 S27 102565 114156 122065 137407 149479 161484 179707 Northeast Severov/hod 257929 551 91455 97709 VMM, 102664 1055% 114383 116740 Northwest Severozahod 185860 399 79929 91837 100343 II1261 120217 129511 134721 East Vzhod 247900 695 117407 126745 131438 165401 181003 201648 213753 West Zahod 217262 590 113231 122972 126242 129910 1.14804 145586 151353 Southeast Jugovzhod 240974 855 17*110 207564 2MJ906 254919 278119 294577 294255 South weit Jugozahod 277528 1001 178323 194143 206975 229895 246045 272923 287786 South Jug 297290 1198 229677 266214 294761 357555 389012 432416 447838 Level Ravno 6X248 102 35025 46548 56434 102491 122862 135336 139831 Total Skupaj 2027127 5918 1127742 1267888 1388772 1591523 1727137 1891864 1965986 Table 7: Proportions of surfaces, settlements. and population in % in Slovenia according to aspects. Preglednica 7: Deleži površin, naselij in števila prebivalce\' v % po razredih ekspozicije. Aspect Ra/rcdi Proportion Proportion Propon ton of population ekspozicije of surfaces of settlements 1869 1900 1931 1961 1971 I9«l 1991 Dele} Dele* Dcle2 Slcvila prebivalcev povrtin naselij 1869 1900 1931 1961 1971 1981 1991 North Sever 11.5 8.9 9.1 9.0 8,8 8.6 8.7 8.6 9.1 Northeast Severovzhod 12.7 9.3 8.3 7,7 7,2 6,5 6,1 6.0 5.9 Northwest Severozahod 9.2 «.7 7.1 7,2 7,2 7,0 7,0 6.8 6,9 Last Vzhod 12.2 11.8 10.4 10,0 9.5 10.4 10.5 10.8 10.9 West Zahod 10.7 10.0 10.0 9.7 9.1 8.2 7,8 7.7 7.7 Southeast Jugovzhod 13.7 14.5 15.8 16,4 18.1 16.0 16.1 <5.6 15,0 Southwest Jugozahod 11.9 16.9 IS,8 15.3 14,9 14.4 14.2 14,4 14.6 South Jug 14,7 20.2 20,4 21,0 21,2 22,5 22.5 22.9 22.8 Level Ravno 3.4 1,7 1.1 J.7 4.0 6.4 7.1 7.2 7.1 Total Skupaj 100.0 100,0 100.0 100,0 100.0 100,0 100.0 100.0 100.0 Table 8: Density ofpopulation in numbers of people per square kilometer in Slovenia according to aspects. Preglednica 8: Gostota prebivalstva v številu ljudi na km: po razredih ekspozicije. Aspcct Razredi Density of population ekspozicije Gostota prebivalstva 1869 1900 1931 1961 1971 1981 1991 North Sever 44 49 52 59 64 70 77 Northeast Severovzhod 36 38 39 40 41 44 45 Northwest Severozahod 43 49 54 60 65 70 73 East Vzhod 47 51 53 67 73 82 86 West Zahod 52 57 58 60 62 67 70 Southeast Jugovzhod 74 86 104 106 116 122 122 Southwest Jugozahod 64 70 75 83 89 98 104 South Jug 77 90 99 120 131 146 151 Level Ravno 51 68 83 150 180 198 205 Total Skupaj 56 63 69 79 85 93 97 Table 9: Indexes of imputation growth in individual periods in Slovenia according to aspects. Preglednica 9: Indeksi rasti števila prebivalcev v posameznih obdobjih po razredih ekspozicije. Aspcct Razredi Indexes of growth of population ekspozicije Indeksi rasti števila prebivalcev 1869 1931 1869 1900 1931 1961 1961 1971 1981 1931 1991 1900 1931 1%1 1991 1971 1981 1991 North Sever 119 147 III 107 113 131 109 109 110 Northeast Severovzhod 107 117 105 102 103 114 103 108 102 Northwest Severozahod 126 134 115 109 111 121 108 108 104 East Vzhod 112 163 108 104 126 129 109 113 105 West Zahod 112 120 109 103 103 117 104 108 104 Southeast Jugovzhod 141 117 117 121 102 115 109 106 100 Southwest Jugozahod 116 139 109 107 111 125 107 111 105 South Jug 128 152 116 111 121 125 109 Ml 104 Level Ravno 161 248 133 121 182 136 120 110 103 Total Skupaj 123 142 112 110 115 124 109 110 104 -1869 -1931 -1991 Figure 7: Dislribulion of populalion according to aspecl and 1869, 1931, and 1991 census figures. Slika 7: Razporeditev prebivalstva ekspozicijah ob popisih prebivalstva leta 1869, 1931 in 1991. -1869 -1931 -1991 Figure 8: Density of population (number of people per square kilometer) according to 1869, 1931. and 1991 census figures. Sitka 8: Gostota prebivalstva (število ljudi na km:) po ekspozicijah ob popisih prebivalstva leta 1869, 1931 in 1991. 4. CONCLUSION Because ridge surfaces in the relief dominate in east-west and southeast-northeast directions, the proportion of south and north as well as northeast and southwest positions is above average. Proportions of individual aspects change with the landscape, heights above sea level, and incline. With the help of the geographical information system we demonstrated that there are statistically significant correlations between aspect on the one hand and the proportion of forest, density of settlements, and density of population on the other. The importance of aspect is partly direct and partly indirect, according to other landscape elements: in any event, we must consider aspect as an equal, in some places even decisive, landscape element in studying correlations between elements in the landscape, regional geography, landscape planning, and elsewhere. BIBLIOGRAPHY - LITERATURA Clark University 1991: The IDRISI Projekt. The Graduate School of Geography. Worcester, USA, 363 strani. Biološki inštitut Jovana lladžija ZRC SAZU, 1993: Karta naravne in potencialne vegetacije v merilu I : 250 000. Ljubljana. G a m s, I. 1988: Osnove pokrajinske ekologije. Ljubljana, 175 strani. G a m s, L, K I a d n i k. D., O ro že n A d a m i č, M. 1994: Zemljevid naravnogeografske regionalizacije Slovenije. Slovenija I : 300 000. Ljubljana. Geodetska uprava Slovenije 1992: Centroidi naselij. Baza podatkov. Ljubljana. Geodetska uprava Slovenije 1991: Stometrski digitalni model reliefa Slovenije. Baza podatkov. Ljubljana. Geografski inštitut Antona Mclika ZRC SAZU 1990-1994: Geografski informacijski sistem Slovenije. Baza podatkov. Ljubljana. P c r k o, D. 1991: Digitalni model reliefa kot osnova za geografski informacijski sistem. Geodetski vestnik 35/4. Ljubljana, str. 269-274. P e r k o, D. 1992 A: Geografski informacijski sistemi v regionalni geografiji in geoekologiji. Dela 9. Ljubljana, str. 186-203. P e r k o, D. 1992 B: Zveze med reliefom in prebivalstvom med letoma 1869 in 1981 v Sloveniji. Doktorska naloga. Ljubljana, 183 strani. Per ko, D. 1993: Ekspozicije v Sloveniji. Geografski obzornik40/4. Ljubljana.str. 22-25. R a d o v a n, D. 1992: Analitično kartografsko senčenje DMR-ja s psevdoslučajnostnimi rastri. Geodetski vestnik 36/3. Ljubljana, str. 250-255. Š i f r e r, M., 1972: Nekatere smeri in pogledi geomorfološkega proučevanja na Slovenskem. Geografski vestnik 44. Ljubljana, str. 35-56. EKSPOZICIJE POVRŠJA V SLOVENIJI Povzetek 1. UVOD Ekspozicija reliefa, ki je značilnost vsakega neravnega površja, je azimut smeri zniževanja površja, torej kot med severom in smetjo gledanja od višje proti nižji nadmorski višini. Opredelimo jo lahko tudi kot smer, kamor je obrnjeno površje. Ekspozicija reliefa torej pove, na katero stran neba gleda površje. Običajno jo izražamo z azimutno oznako od 0 do 360" v smeri urinega kazalca. Ekspozicija reliefa je pomembna naravna pokrajinska prvina (Gams 1988), saj vpliva na količino sprejete sončne energije, ki je pomemben dejavnik pri geomorfoloških, hidroloških, pedoloških, bioloških in drugih naravnih procesih ter hkrati pomemben dejavnik pri poselitvi in različnih dejavnostih človeka. Včasih ima lahko celo odločilen pomen, na primer pri razporeditvi vinogradov, gozda, naselij, smučišč in podobno. Pomebno vlogo pri ckspozicijah igrajo nakloni. Med ckspozicijo in naklonom sicer ni neposredne povezave, saj koeficient njune povezanosti statistično ni značilen, pač pa z naraščanjem naklona rase izrazitost ckspozicije reliefa in njen vpliv na ostale pokrajinske sestavine. Ekspozicije lahko združujemo v razrede, ki jih poimenujemo po straneh neba. Najpreprostejše je združevanje v štiri 90" široke razrede, ki jih poimenujemo po štirih osnovnih straneh neba: severne ckspozicije imajo azimut med 0 in 45° in med 315 in 360°, vzhodne med 45 in 135*, južne med 135 in 225", zahodne pa med 225 in 315®. V nekaterih primerih (sliki I in 2) lahko ekspozicije razdelimo le na dva 180" široka razreda: na severne (med 0 in 90° ter 270 in 360") in južne ekspozicije (med 90 in 270°) ali na vzhodne (med 0 in 180") in zahodne ekspozicije (med 180 in 360"). Bolj natančno pa je združev anje v osem 45" širokih razredov, ki jih poimenujemo po štirih osnovnih in štirih stranskih straneh neba: severne ckspozicije imajo azimut med 0,0 in 22,5" in med 337,5 in 360,0", severovzhodne med 22,5 in 67,5°, vzhodne med 67,5 in 112,5°, jugovzhodne med 112,5 in 157,5®, južne med 157,5 in 202,5°, jugozahodne med 202.5 in 247,5", zahodne med 247,5 in 292,5°, severozahodne pa med 292,5 in 337,5°. Če ekspozicije pomnožimo z nakloni, dobimo sliko 3, kjer so območja z nizkimi vrednostmi (severne ekspozicije in majhni nakloni) bela, območja z visokimi vrednostmi (južne ekspozicije in veliki nakloni) pa Črna. Taka predstavitev reliefa je še bolj plastična, še posebej, Če z belo barvo predstavimo le najnižje vrednosti in s črno barvo najvišje vrednosti, vmesne vrednosti pa s sivimi poltoni (Radovan 1992), (slika 4). Zelo ostro se vidijo nekateri prelomi (na primer savski in idrijski prelom), nekateri narivi (na primer južni rob Trnovskega gozda, Nanosa in Hrušicc), večje in izrazite doline (na primer dolina Save med Julijskimi Alpami in Karavankami, med Bohinjskim in Blejskim jezerom ter skozi Posavsko hribovje, dolina Drave med Pohorjem in Kozjakom, dolina Kolpe in Čepovanska dolina), lepo pa se vidi tudi razmerje med razgibanim in nerazgibanim svetom. 2. NAČIN DELA Ekspozicije v Sloveniji smo določili s pomočjo geografskega informacijskega sistema, ki omogoča sorazmerno enostavno in hitro določanje ekspozicij tudi za večja območja (Perko 1993), in s pomočjo stometrskega digitalnega modela reliefa Slovenije (Geodetska uprava Slovenije 1991), ki vsebuje nadmorske višine ogljišč kvadratne mreže, kjer ima vsak kvadratek osnovnico 100 m, njegova površina pa meri 10 000 m:, torej 1 ha. Na reliefni sloj smo položili centroide naselij (Geodetska uprava Slovenije 1992), torej točke, ki predstavljajo zgostitvena jedra naselij, in nanje navezali prebivalstvcnc podatke. Zaradi metodološke problematičnosti določevanja ccntroidov naselij za površinsko velika naselja, na primer razložena naselja oziroma naselja iz samotnih kmetij (Kokra, Strojna itd.) ter velika naselja (Ljubljana. Maribor itd.), je treba razporeditev naselij in prebivalstva po ekspozicijah in iz tega izhajajoče kazalce vzeti kot ocene, ki pa so zaradi zelo velikega števila podatkov dovolj reprezentativne in kažejo na nekatere zakonitosti (Perko 1992 B). V okviru geografskega informacijskega sistema Slovenije (Perko 1991), ki ga predvsem za potrebe rcgionalnogeografskih preučevanj in preučevanj povezanosti med pojavi v pokrajini (Perko 1992 A), pod naslovom Geografski informacijski sistem Slovenije razvijamo na Geografskem inštitutu Antona Melika Znanstvenoraziskovalnega centra SAZU, smo s pomočjo računalniškega programskega paketa IDR1SI (Clark University 1991), ki izračuna ckspozicijo vsakega kvadratka na osnovi spreminjanja nadmorskih višin tega kvadratka in vseh njegovih osmih sosedov, izračunali ckspozicijo za 2 025 652 hektarskih kvadratkov. 3,4 % površja Slovenije ima naklon manjši od 0,5° in tako površje v prispev ku obravnavamo kot ravno, torej nima ckspozicije. Pričakovali bi, da je ostalo površje enakomerno porazdeljeno med posamezne razrede ekspozicij, dejansko pa so razlike kar opazne. 3. UGOTOVITVE 3.1. POVRŠINE Ko odštejemo raven svet, torej 3,4 % površine Slovenije (vsega ravninskega sveta s povprečnim naklonom pod 2" je 14,3 %), ostane v povprečju na vsako od osmih ekspozicij 12,1 % ozemlja. Dejansko pa je največ južnih leg, 14,7 %, kar je za petino več od povprečne, teoretične vrednosti in za skoraj dve tretjini več od severozahodnih leg, ki pomenijo le 9,2 % površine Slovenije, kar je za četrtino manj od povprečne vrednosti. Nadpovprečno se pojavljajo še jugozahodne, severovzhodne in vzhodne lege, podpovprečno pa še zahodne, seveme in jugovzhodne lege. To si lahko razlagamo z glavno slemenitvijo v Sloveniji v smereh zahod - vzhod in severozahod - jugovzhod, saj jc površina posameznih ekspozicij odvisna tudi od slemenitve površja. Tako naj bi teoretično pri slemenitvi v smeri zahod - vzhod prevladovale severne in južne lege, pri slemenitvi v smeri sever - jug pa vzhodne in zahodne lege. Zato naj bi bilo v alpskem svetu več južnih in severnih leg, kar drži (preglednica 2), saj južne in severne ekspozicijc predstavljajo skoraj tretjino vseh površin, vzhodne in zahodne pa le petino, v dinarskem svetu s slemenitvijo v smeri severozahod -jugovzhod pa več severovzhodnih in jugozahodnih leg. kar prav tako drži, saj severovzhodne in jugozahodne ekspozicije pomenijo tretjino, severozahodne in jugovzhodne pa niti petino vseh površin. Večji delež južnih ekspozicij od severnih si razlagamo tudi s tem, daje na severni meji večina severnih pobočij v Avstriji, južnih pa v Sloveniji, prevlado vzhodnih ekspozicij nad zahodnimi pa s podobnimi razmerami na meji z Italijo, kjer v grobem zahodna pobočja pripadajo Italiji in vzhodna Sloveniji. Na vzhodni in južni meji proti Hrvaški pa je več ravninskega in gričevnatega sveta, tako da so pobočja manj strma in bolj podolgovata, zato ne morejo nadomestiti manjka zahodnih pobočij v Italiji in severnih v Avstriji. To lahko opišemo tudi kot dejstvo, da z Avstrijo in Italijo poteka meja večinoma po grebenih in slemenih, s HrvaŠko pa predvsem po vodotokih, torej dolinah. Možna razlaga je tudi, da imajo ekspozicije z večjo površino manjši naklon in obratno. Postavimo osnovno hipotezo, da sta površina posameznih ekspozicij in njihov povprečni naklon povezana, in ničelno hipotezo, ki pravi, da ni povezanosti, oziroma da so vse razlike, ki nastopajo, slučajne. Koeficient povezanosti med površino in povprečnim naklonom je -0,6632, kar je v absolutnem smislu visok koeficient, ki z negativnim predznakom kaže, da se z manjšanjem naklona veča površina. Toda t-test koeficienta povezanosti pokaže, daje izračunani t, ki ima vrednost 2,1709, manjši od kritične vrednosti t, ki ima pri 99,9 % zaupanju vrednost 5,959. Zato lahko z 99,9 % verjetnostjo zavrnemo osnovno hipotezo o povezanosti in sprejmemo ničelno hipotezo, da med površino posameznih ekspozicij in povprečnim naklonom ni statistično pomembne povezanosti. Tako torej ne moremo reči, da imajo tiste ekspozicije, ki imajo manjši povprečni naklon, večjo površino. Če primerjamo razporeditev površin ekspozicij po makrorcgijah Slovenije (Gams, Kladnik in Orožen Adamič 1994), lahko ugotovimo še večje neskladje. Tako je v alpskem svetu razmerje med deležem južnih leg, ki jih je največ, in zahodnih leg, ki jih je najmanj, skoraj 2 proti I. Na dnu Ljubljanske kotline je največ južnih in najmanj severozahodnih leg, razmerje pa je več kot 4 proti 1. V subpanonskcm svetuje največ južnih leg in najmanj severozahodnih leg, razmerje pa je 2 proti 1. V dinarskem svetuje največ jugozahodnih leg in najmanj severozahodnih, razmerje pa je manj kot 2 proti 1. V primorskem svetu pa je največ jugozahodnih in najmanj zahodnih, razmerje pa je 2,5 proti I (preglednica 2). Najmanjši in največji delež kakšne ekspozicije je na dnu Ljubljanske kotline, kjer jc severozahodnih leg le 5,7 %, južnih pa kar 23,7 % (preglednica 2). Pri drugih makrorcgijah razlike niso tako velike. 3.2. POVPREČNI NAKLONI Povprečni naklon Slovenije je 13,1*. Med ckspozicijami imajo največji povprečni naklon severozahodne lege, kar 15,1*, nato pa severne lege s 14,5". Najmanjši povprečni naklon imajo jugovzhodne lege s 13,0' in vzhodne celo le s 12,6°. Razlika med največjim in najmanjšim povprečnim naklonom jc 19 %. Vzhodne, jugovzhodne in južne lege imajo povprečni naklon pod povprečjem Slovenije. Zanimivo je. da se delež posameznih ekspozicij po naklonih spreminja. Na površju z nakloni med 0 in 6 prevladujejo južne ali jugozahodne lege, nato do 20" predvsem jugozahodne, nekako do 50" potem spet južne lege, med 50 in 70" severozahodne in nad 70° severne lege. Na naklonih do 30° je najmanj severozahodnih leg, med 30 in 50° zahodnih, med 50 in 60° severovzhodnih, nad 60° pa jugozahodnih leg. Kako se spreminja delež površin posameznih ckspozicij z naraščanjem naklona, prikazuje slika 5. V grobem delež severnih in severozahodnih leg z rastjo naklona narašča, južnih in jugozahodnih pada, ostale lege pa so sorazmerno enako zastopane pri vseh naklonih. 3.3. POVPREČNA NADMORSKA VIŠINA Največjo povprečno nadmorsko višino imajo s 593 m severozahodne lege, nato pa zahodne lege s 575 m. Najmanjšo povprečno nadmorsko višino imajo jugozahodne lege s 567 m in vzhodne z le 549 m. Razlika med največjo in najmanjšo povprečno nadmorsko višino je samo 5 %. Le severovzhodne in vzhodne lege imajo povprečno nadmorsko višino pod povprečjem Slovenije, ki je 557 m. Zanimivo je, da se delež posameznih ckspozicij po stometrskih višinskih pasovih spreminja. Na površju z nadmorsko višino med 0 in 400 m prevladujejo južne lege, nato do 900 m jugozahodne, nekako do 1900 m potem spet južne lege, višje pa predvsem jugovzhodne in južne lege. Na nadmorskih višinah do 1100 m je najmanj severozahodnih leg, med 1100 in I700m zahodnih in severozahodnih, med 1700 in 2200 m severnih, viije pa zahodnih in jugovzhodnih leg. Primarni višek ravnega sveta, torej površja brez ekspozicije, je v stometrskem višinskem pasu med 100 in 200 m, kamor spadajo nekatera največja območja ravnega sveta v Sloveniji (na primer Pomurska ravnina. Krška kotlina, del Vipavske doline, pa tudi severni nizki del Bele krajine), sekundarni pa so med 500 in 600 m. 700 in 800 m. 1200 in 1300 m, kjer leži del največjih alpskih planot (na primer Jelovica. Pokljuka), pa tudi del Pohorja, ter med 1700 in 1800 m. To si razlagamo s tem, da imamo v slovenskem alpskem svetu uravnave v višinah med 2300 in 2500 m, okrog 1800 m, okrog 1600 m, med 1500 in 1550 m in med 1100 in 1200 m, v dinarskem svetu med 1000 in 1500 m, v subpanonskem in submediteranskem obrobju pa še nižje (Šifrcr 1972). Kako se spreminja delež površin posameznih ckspozicij z naraščanjem nadmorske višine, prikazuje slika 6. V grobem so posamezne ekspozicije pri vseh višinskih pasovih sorazmerno enako zastopane, sploh pa v primerjavi z nakloni. 3.4. EKSPOZICIJE IN GOZD Delež gozda smo določali na osnovi digitaliziranega zemljevida Naravne in potencialne vegetacije v merilu I : 250 000 (Biološki inštitut Jovana Hadžija ZRC SAZU, 1993). Najbolj na gosto so z gozdom porasle severovzhodne lege z 61,9 ha gozda na knr površja in severne lege z 61,7 ha na km:. Na južnih legah je 49,0 ha gozda na km2 površja, na ostalih legah pa med 50 in 60 ha na km1. Delež gozda se torej manjša od severnih proti južnim ckspozicijam. Na ravnem svetuje gostota komaj 14,9 ha gozda na km- površja. Razmerje med gozdnimi in negozdnimi površinami je na severovzhodnih in severnih legah 1 proti 1,6, na južnih pa skoraj 1 proti I. Na jugozahodnih legah je šc za malenkost več gozdnih površin od negozdnih, na južnih legah pa je gozda žc manj kot polovico vseh površin. Od vseh gozdnih površin v Sloveniji jih je 14,5 % na severovzhodnih legah, 13,3 % na južnih legah, 13,2 % na severnih legah, po 12,8 % na vzhodnih in jugozahodnih legah, 11,6 % na jugovzhodnih legah, 10,8 % na zahodnih in 10,1 % na severozahodnih legah, na ravnem pa niti odstotek. Kakšna je zgostitev gozdnih površin po ekspozicijah, pokaže koeficient koncentracije, ki ima vrednosti med 0 in I. Kadar ima koeficient koncentracije nekega pojava vrednost 1, je ta pojav zgoščen v enem samem razredu, v našem primeru na eni sami ckspoziciji, kadar pa ima vrednost 0, pa je ta pojav enakomerno zastopan v vseh razredih in koncentracije ni. V pokrajini ima koeficient koncentracije le redko skrajne vrednosti. Koeficient koncentracije gozdnih površin po ekspozicijah (upoštevaje tudi raven svet) je 0,1217, kar je za dobro petino več, kot koncentracija površin posameznih ekspozicij. To žc kaže na določeno povezanost ekspozicije z deležem gozda. Podobno kot smo ugotavljali povezanost naklona in površin ekspozicije, lahko ugotavljamo tudi povezanost med ckspozicijo in deležem gozda. Naša hipoteza se glasi, da se razporeditev vseh površin po ekspozicijah značilno razlikuje od razporeditve gozdnih površin po ekspozicijah, ničelna hipoteza pa, da razlik ni. Vrednost hi-kvadrata jc 7814,5, kar je bistveno več od kritične (mejne) vrednosti hi-kvadrata, ki je pri osmih razredih ekspozicij in 99,9 % zaupanju 24,3. Zato lahko zavrnemo ničelno hipotezo in z 99,9 % verjetnostjo sprejmemo osnovno hipotezo, da se razporeditev površin in razporeditev gozda statistično pomembno (značilno) razlikujeta, lako lahko sklepamo, da je med ekspozicijo in deležem gozda določena povezava. Koeficient povezanosti med ekspozicijami in razporeditvijo gozdnih in negozdnih površin, ki smo ga izračunali na osnovi kontingenčne tabele, ima vrednost le 0,0946, kar je v absolutnem smislu malo, vendar pa je pri več kot dveh milijonih podatkov, ki smo jih upoštevali pri izračunu, t-test koeficienta pokazal, daje povezanost statistično značilna, saj je izračunani t z vrednostjo 133 bistveno večji od kritične vrednosti t pri 99,9 % zaupanju, kar dokazuje sorazmerno močno povezanost. 3.5. EKSPOZICIJE IN NASELJA Na severnih, severovzhodnih in severozahodnih legah pride na vsako naselje med 400 in 500 ha površine, na vzhodnih in zahodnih legah med 300 in 400 ha, na jugovzhodnih, jugozahodnih in južnih legah pa med 200 in 300 ha. To pomeni, da se gostota naselij veča od severnih proti južnim ekspozicijam. Na rav nem svetu pa je gostota naselij najmanjša, skoraj 700 ha na naselje. Razlog za manjšo gostoto naselij je predvsem v tem, daje raven svet prepuščen v večji meri kmetijski izrabi, ali pa so to poplavna območja, kjer bi bila naselja ogrožena. Razen tega, daje naselij na ravnem svetu res manj, pa drži tudi dejstvo, da so le-ta tam večja. Koeficient koncentracije za naselja je 0,1314 (raven svet je izločen), kar je skoraj trikrat več od koeficienta koncentracije za površine, ki ima vrednost 0,0499. To kaže na določen pomen ekspozicije za razporeditev naselij, saj bi si bila sicer oba koeficienta enaka. Osnovna hipoteza se glasi, da je razporeditev površin po ekspozicijah različna od razporeditve naselij po ekspozicijah, ničelna hipoteza pa, da ni. Izračunani hi-kvadrat ima vrednost 382,1, kritična vrednost hi-kvadrata pri 99,9 % zaupanju pa 24,3. Zato lahko z 99,9 % verjetnostjo sprejmemo osnovno hipotezo, ki kaže na povezavo med ekspozicijo in deležem naselij. 3.6. EKSPOZICIJE IN PREBIVALSTVO Število prebivalcev je od leta 1869 do leta 1991 raslo prav na vseh legah, vendar različno. Med letoma 1869 in 1931 je najbolj naraščalo na jugovzhodnih legah, kjer seje Število prebivalcev povečalo skoraj za polovico, najmanj pa na severovzhodnih legah, kjer se je povečalo le za 7 %. Na jugovzhodnih legah seje torej število prebivalcev povečalo šestkrat bolj kot na severovzhodnih legah. Najbolj izrazito pa se je število prebivalcev, razumljivo, povečalo na ravnem svetu, skoraj za dve tretjini. Med letoma 1931 in 1991 seje število prebivalcev najbolj povečalo na vzhodnih legah, skoraj za dve tretjini, najmanj pa spet na severovzhodnih legah, za manj kot petino. Na vzhodnih legah se je tako število prebivalcev povečalo za skoraj štirikrat bolj kot na severovzhodnih legah. Na ravnem svetu seje v istem obdobju število prebivalcev povečalo za 150%. Delež prebivalstva seje med letoma 1869 in 1991 povečal le na vzhodnih legah z 10,4 % na 10,9 % in južnih legah z 20,2 % na 22,8 %, ter seveda na ravnem svetu, kjer seje delež povečal kar za več kot Štirikrat, z 1,7 % na 7,1 %. Leta 1991 je na jugovzhodnih, jugozahodnih in južnih legah živela dobra polovica, na severnih, severovzhodnih in severozahodnih legah pa komaj petina vsega prebivalstva Slovenije. Leta 1869 so bile najbolj gosto naseljene jugozahodne lege s 77 ljudmi na kmJ, najbolj redko pa severovzhodne lege s 36 ljudmi na km2. Razmerje je bilo približno 2 proti I. Leta 1991 so bile spet najbolj gosto naseljene jugozahodne in najmanj severovzhodne lege, razmeije pa je naraslo na več kot 3 proti 1. Na ravnem svetuje bila gostota prebivalstva leta 1869 komaj 51 ljudi na knv, kar je pod takratnim povprečjem Slovenije, ki je bilo 56 ljudi na knr, leta 1991 pa že 205 ljudi na km3, kar štirikrat več kot leta 1869 in več kot dvakrat več od povprečne gostote prebivalstva Slovenije leta 1991, ki je bila 97 ljudi na knr. Koncentracija prebiv alstva po ekspozicijah je bila leta 1991 0,1714, kar je triinpolkrat več od koncentracije površin in za tretjino več od koncentracije naselij. T udi za razmestitev prebivalstva lahko ugotavljamo pomen ekspozicije s preizkusom osnovne hipoteze, ki se glasi, da se razporeditev površin posameznih ekspozicij značilno razlikuje od razmestitve prebivalstva, in ničelne hipoteze, da se ne. Za leto 1869 ima izračunani hi-kvadrat vrednost 75166,9. Ker je kritična vrednost hi-kvadrata pri 99,9% zaupanju samo 24,3. lahko z 99,9 % vcijctnostjo sprejmemo osnovno hipotezo, da se razporeditev površin značilno razlikuje od razporeditve prebivalstva. Od tega leta naprej je hi-kvadrat stalno naraščal in leta 1991 dosegel vrednost 223 237, kar je skoraj desettisočkrat več od kritične vrednosti. To pomeni, daje razporeditev prebivalstva močno navezana na ekspozicijo in daje med letoma 1869 in 1991 stalno naraščala. 4. SKLEP V Sloveniji imajo zaradi slemenitve reliefa v prevladujočih smereh vzhod - zahod in jugovzhod - severozahod nadpovprečno visok delež površin južne in severne ter severovzhodne in jugozahodne lege. Deleži posameznih ckspozicij se spreminjajo s pokrajinami, z nadmorsko višino in naklonom. S pomočjo geografskega informacijskega sistema smo dokazali, daje med ekspozicijo na eni strani ter deležem gozda, gostoto naselij in gostoto prebivalstva na drugi strani statistično pomembna povezanost. Pomen ckspozicijc je deloma neposreden in deloma posreden, prek drugih pokrajinskih prvin, vsekakor pa moramo ekspozicijo pri preučevanju povezav med pojavi v pokrajini, regionalni geografiji, pokrajinskem načrtovanju in drugod upoštevali kot enakovredno, ponekod celo odločujočo pokrajinsko prvino.