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

2014 ◽  
Vol 11 (10) ◽  
pp. 14667-14698 ◽  
Author(s):  
M. Klinge ◽  
J. Böhner ◽  
S. Erasmi
Keyword(s):  
Central Asia ◽  
Regional Scale ◽  
Distribution Patterns ◽  
Slope Aspect ◽  
Climate Conditions ◽  
Arid Central Asia ◽  
Investigation Area ◽  
Forest Limit ◽  
Forest Distribution ◽  
Semi Arid

Abstract. 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.

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

2015 ◽  
Vol 12 (10) ◽  
pp. 2893-2905 ◽  
Author(s):  
M. Klinge ◽  
J. Böhner ◽  
S. Erasmi
Keyword(s):  
Central Asia ◽  
Regional Scale ◽  
Strong Relationship ◽  
Distribution Patterns ◽  
Tien Shan ◽  
Slope Aspect ◽  
Climate Conditions ◽  
Investigation Area ◽  
Forest Limit ◽  
Forest Distribution

Abstract. 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.

Late Quaternary lake-level and climate changes in arid central Asia inferred from sediments of Ebinur Lake, Xinjiang, northwestern China

2019 ◽  
Vol 92 (2) ◽  
pp. 416-429 ◽  
Author(s):  
Jianchao Zhou ◽  
Jinglu Wu ◽  
Long Ma ◽  
Mingrui Qiang
Keyword(s):  
Grain Size ◽  
Central Asia ◽  
North Atlantic ◽  
Lake Level ◽  
Climate Changes ◽  
Late Quaternary ◽  
Study Region ◽  
Climate Conditions ◽  
Arid Central Asia ◽  
Ebinur Lake

AbstractArid central Asia plays an important role in global climate dynamics, but large uncertainties remain in our understanding of the region's hydroclimate variability during the Late Quaternary. Here we present a new, high-resolution record of lacustrine sediment grain-size and element chemistry from Ebinur Lake, which was used to infer lake conditions and related climate changes in the study region between ca. 39.2 and 3.6 ka. End-member modeling analysis of grain-size data and PCA of elemental data show that lake level fluctuated dramatically from 39.2 to 34.0 ka. Subsequently, Ebinur Lake experienced a high stand from 34.0 to 28.0 ka, under humid climate conditions. The subsequent period, from 28.0 to 12.0 ka, was characterized by lake regression under dry climate conditions, whereas afterward (12.0–3.6 ka), considerably higher lake levels and humid conditions again prevailed. Millennial-scale abrupt climate changes, such as Heinrich events (H3 and H1) and the Younger Dryas, which are documented in the North Atlantic region, are also detected in the sediment record from Ebinur Lake. Comparisons with other sediment records from arid central Asia generally support the claim that climate change in this region was influenced mainly by variations in North Atlantic sea surface temperatures, through the westerlies.

scholarly journals Midge distribution patterns at multiple spatial scales in shallow Finnish lakes revealed through sedimentary records

2019 ◽  
Vol 23 (2) ◽  
Author(s):  
Tomi Luoto ◽  
Liisa Nevalainen ◽  
Veli-Pekka Salonen
Keyword(s):  
Spatial Scales ◽  
Regional Scale ◽  
Environmental Parameters ◽  
Distribution Patterns ◽  
Habitat Characteristics ◽  
Site Specific ◽  
Climate Conditions ◽  
Sedimentary Records ◽  
Multiple Spatial Scales ◽  
Eastern Finland

This study was based on sedimentarymidge (Diptera:Nematocera) assemblages from multilake datasets along environmental transects from Finland (regional), southern Finland (semiregional), and Helsinki district (local) and an intralake dataset from eastern Finland (site-specific). The aim was to examine scale-dependencies in midge distribution. The results imply that distribution and abundance of midge taxa are related to scale: on the regional scale the forcing factors are related to prevailing climate conditions, on semiregional scale they are related to water quality, on more local scales predation pressure is the key variable and on site-specific scales habitat characteristics determine the species assemblages. Although the number of study siteswas not equal and not all environmental parameters were possible to measure fromall spatial scales, it is apparent that caution is required in midge-based environmental assessments, because changes in faunal composition are driven by factors operating at different spatial scales.

scholarly journals Quantifying the Variability of Forest Ecosystem Vulnerability in the Largest Water Tower Region Globally

2021 ◽  
Vol 18 (14) ◽  
pp. 7529
Author(s):  
Siqi Sun ◽  
Yihe Lü ◽  
Da Lü ◽  
Cong Wang
Keyword(s):  
Forest Ecosystems ◽  
Human Impacts ◽  
Regional Scale ◽  
Principal Component ◽  
Tibet Plateau ◽  
Slope Aspect ◽  
Environmental Disturbances ◽  
Restoration Planning ◽  
Development Goals ◽  
Qinghai Tibet Plateau

Forests are critical ecosystems for environmental regulation and ecological security maintenance, especially at high altitudes that exhibit sensitivity to climate change and human activities. The Qinghai-Tibet Plateau—the world’s largest water tower region—has been breeding many large rivers in Asia where forests play important roles in water regulation and water quality improvement. However, the vulnerability of these forest ecosystems at the regional scale is still largely unknown. Therefore, the aim of this research is to quantitatively assess the temporal–spatial variability of forest vulnerability on the Qinghai-Tibet Plateau to illustrate the capacity of forests to withstand disturbances. Geographic information system (GIS) and the spatial principal component analysis (SPCA) were used to develop a forest vulnerable index (FVI) to assess the vulnerability of forest ecosystems. This research incorporates 15 factors covering the natural context, environmental disturbances, and socioeconomic impact. Results indicate that the measure of vulnerability was unevenly distributed spatially across the study area, and the whole trend has intensified since 2000. The three factors that contribute the most to the vulnerability of natural contexts, environmental disturbances, and human impacts are slope aspect, landslides, and the distance to the farmland, respectively. The vulnerability is higher in forest areas with lower altitudes, steeper slopes, and southerly directions. These evaluation results can be helpful for forest management in high altitude water tower regions in the forms of forest conservation or restoration planning and implementation towards sustainable development goals.

scholarly journals A paleomagnetic record in loess–paleosol sequences since late Pleistocene in the arid Central Asia

2018 ◽  
Vol 70 (1) ◽  
Author(s):  
Guanhua Li ◽  
Dunsheng Xia ◽  
Erwin Appel ◽  
Youjun Wang ◽  
Jia Jia ◽  
...  
Keyword(s):  
Central Asia ◽  
Late Pleistocene ◽  
Arid Central Asia

scholarly journals Holocene changes in African vegetation: tradeoff between climate and water availability

2014 ◽  
Vol 10 (2) ◽  
pp. 681-686 ◽  
Author(s):  
C. Hély ◽  
A.-M. Lézine ◽  
APD contributors
Keyword(s):  
West Africa ◽  
Water Availability ◽  
Regional Scale ◽  
Plant Distribution ◽  
Climate Conditions ◽  
Tropical Plants ◽  
Plant Migration ◽  
Spatio Temporal ◽  
The Individual ◽  
Instrumental Records

Abstract. Although past climate change is well documented in West Africa through instrumental records, modeling activities, and paleo-data, little is known about regional-scale ecosystem vulnerability and long-term impacts of climate on plant distribution and biodiversity. Here we use paleohydrological and paleobotanical data to discuss the relation between available surface water, monsoon rainfall and vegetation distribution in West Africa during the Holocene. The individual patterns of plant migration or community shifts in latitude are explained by differences among tolerance limits of species to rainfall amount and seasonality. Using the probability density function methodology, we show here that the widespread development of lakes, wetlands and rivers at the time of the "Green Sahara" played an additional role in forming a network of topographically defined water availability, allowing for tropical plants to migrate north from 15 to 24° N (reached ca. 9 cal ka BP). The analysis of the spatio–temporal changes in biodiversity, through both pollen occurrence and richness, shows that the core of the tropical rainbelt associated with the Intertropical Convergence Zone was centered at 15–20° N during the early Holocene wet period, with comparatively drier/more seasonal climate conditions south of 15° N.

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