Modeling forest lines and forest distribution patterns with remote-sensing data in a mountainous region of semiarid central Asia

Satellite images and digital elevation models provide an excellent database to analyze forest distribution patterns and forest limits in the mountain regions of semiarid central Asia on the regional scale. For the investigation area in the northern Tien Shan, a strong relationship between forest distribution and climate conditions could be found. Additionally areas of potential human impact on forested areas are identified at lower elevations near the edge of the mountains based on an analysis of the differences in climatic preconditions and the present occurrence of forest stands. The distribution of spruce (Picea schrenkiana) forests is hydrologically limited by a minimum annual precipitation of 250 mm and thermally by a minimum monthly mean temperature of 5 °C during the growing season. While the actual lower forest limit increases from 1600 m a.s.l. (above sea level) in the northwest to 2600 m a.s.l. in the southeast, the upper forest limit rises in the same direction from 1800 m a.s.l. to 2900 m a.s.l.. In accordance with the main wind directions, the steepest gradient of both forest lines and the greatest local vertical extent of the forest belt of 500 to 600 m to a maximum of 900 m occur at the northern and western mountain fronts. The forests in the investigation area are strongly restricted to north-facing slopes, which is a common feature in semiarid central Asia. Based on the presumption that variations in local climate conditions are a function of topography, the potential forest extent was analyzed with regard to the parameters slope, aspect, solar radiation input and elevation. All four parameters showed a strong relationship to forest distribution, yielding a total potential forest area that is 3.5 times larger than the present forest remains of 502 km2.

Modelling forest lines and forest distribution patterns with remote sensing data in a mountainous region of semi-arid Central Asia

Satellite images and digital elevation models provide an excellent database to analyse forest distribution patterns and forest limits in the mountain regions of semi-arid Central Asia at the regional scale. For the investigation area in the northern Tien Shan a strong relation between forest distribution and climate conditions could be found. Additionally areas of potential human impact on forested areas are identified at lower elevations near the mountain border based on an analysis of the differences of climatic preconditions and present occurrence of forest stands. The distribution of spruce (Picea schrenkiana) forests is hydrologically limited by a minimum annual precipitation of 250 mm and thermally by a minimum monthly mean temperature of 5 °C during the growing season. While the actual lower forest limit increases from 1600 m a.s.l. in the northwest to 2600 m a.s.l. in the southeast, the upper forest limit takes the same course from 1800 to 2900 m a.s.l. In accordance with the main wind directions, the steepest gradient of both forest lines and the greatest local vertical extent of the forest belt of 500 to 600 m and maximum 900 m occur at the northern and western mountain fronts. The forests in the investigation area are strongly restricted to north facing-slopes, which is a common feature in semi-arid Central Asia. Based on the presumption that variations in local climate conditions are a function of topography, the potential forest extent was analysed with regard to the parameters slope, aspect, solar radiation input and elevation. All four parameters showed a strong relationship to forest distribution, yielding a total potential forest area that is 3.5 times larger than the present forest remains of 502 km2.

Hochlagenaufforstungen in Lawinenverbauungen im Berner Oberland

Regeneration at high altitude in avalanche control stands in the Bernese Oberland Since the 1950s, high altitude regeneration projects have been carried out in the avalanche control areas of the Bernese Oberland, using site-appropriate seedlings of domestic provenance from the cantonal nurseries. These plantations are intended to prevent, in the medium to long term, the start of avalanches. On the one hand, the article presents an analysis of the measures taken since 1995, and the field measurements made in the high altitude plantation at Schwanderort (1730–1780 m) above Brienz. This provides information on the development of young Spruce under extreme external conditions. On the other hand, the article investigates from what age the regeneration can provide avalanche protection functions, based on the growth characteristics of 112 trees of different ages, from 24 avalanche protection projects. Site conditions at high altitude are much more extreme and vary more from year to year than at lower altitude. Nineteen years after the plantation at Schwanderort, 60% of the Spruce are still alive; over this period, their average height has increased from 19 cm to 152 cm. Because of the short vegetative period, their height growth takes place between 20 June and end of July, and is stopped or strongly reduced when average temperatures are below 10°C. Analysis shows that at the upper forest limit, one must wait 45–50 years before regeneration can fulfil its avalanche protection function.

Variability of Anthoxanthum species in Poland in relation to geographical-historical and environmental conditions: morphological and anatomical variation

Three Anthoxanthum species are found in Poland: the native A. odoratum L. s. str. and A. alpinum Á. Löve & D. Löve, and the alien A. aristatum Boiss. Major problems within this genus concern: (1) population variation of the native A. odoratum, representing various phases of ecological expansion to anthropogenic habitats; (2) population variation of A. odoratum and A. alpinum along the altitudinal transect; and (3) variation between populations of A. aristatum colonizing new areas and habitats outside its natural range of distribution (chorological expansion). In this study, morphological and anatomical variation of the three Polish Anthoxanthum species was analysed in detail. The variation of A. odoratum and A. aristatum was analysed in respect of environmental differences: habitat types and soil parameters. In the Babia Góra massif, variability distribution along the altitudinal transect was analysed for two vicariants: A. odoratum and A. alpinum. A odoratum in this massif does not cross the upper forest limit (i.e. forest line), and lower montane populations are morphologically very similar to lowland populations. Morphological and anatomical differences were detected between populations of A. alpinum along the altitudinal transect in the Babia Góra massif, with distinct upper montane populations. Moreover, clear morphological differences were found between the two altitudinal vicariants. Lowland populations of A. odoratum are characterized by great morphological variation, only weakly correlated with the type of occupied habitat and the phase of ecological expansion. The detected morphological variation reflects only to a limited extent the environmental variation of occupied habitats, and is not significantly correlated with the phase of chorological expansion. Some soil parameters are significantly correlated with some morphological characters studied in all the Anthoxanthum species. The analysed anatomical features of stems and leaves show continuous variation in the three species.