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2016 | Buch

Climate Change, Glacier Response, and Vegetation Dynamics in the Himalaya

Contributions Toward Future Earth Initiatives

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Über dieses Buch

This book provides information essential for anyone interested in climate and environmental change of the Himalayan region, including land and resource managers, environmental planners, conservationists, environmentalists, geographers, climatologists, ecologists, and students. The book is unique in its coverage of the current understanding of the science of climate change in the Himalayan mountain system and of the major impacts on physical systems and ecosystems. The book gives an overview of the physical science basis of climate change and explains drivers and processes of glacier and vegetation dynamics.

The book covers relevant aspects of accelerated climate change observed in the Himalayan mountain system, and highlights the regional differentiation of climatic changes and associated environmental modifications. The focus is on climate variability and change, and how physical systems and ecosystems respond to climate change impacts. Consequences include impacts on physical systems such as glacier shrinkage, glacial lake outburst floods, altered hydrological characteristics, permafrost warming and thawing, and mass movements on slopes. Climate change is also a powerful stressor on ecosystems and induces range shifts of plant and animal species and alterations in terms of phenology, biomass, plant cover, plant group dominance and species composition. Thus, ecosystem structure and functioning will be strongly affected.

The book has an introductory chapter followed by a section on climate change, a section on impacts on glaciers and hydrology, and a section on vegetation dynamics. Each section has several chapters presenting key concepts, major drivers and key processes of environmental change in the Himalayan region from different perspectives. Climate change impacts in the Himalaya have not been studied in much detail, and respective findings were not presented so far in a comprehensive overview. This book summarizes the current knowledge of interactions between climate change and the dynamics of glaciers, hydrology, and vegetation.

Inhaltsverzeichnis

Frontmatter
Chapter 1. Climate Change and Dynamics of Glaciers and Vegetation in the Himalaya: An Overview
Abstract
Mountains are globally significant as ‘water towers’ of the Earth, as core areas of biodiversity and as source regions for important natural resources and ecosystem services. The ecological integrity of mountain environments is increasingly threatened by global environmental changes including climate change to which physical and ecological systems in mountains are highly vulnerable. Global warming rates have been higher in mountain regions compared to the global mean and have strongly affected the cryosphere, mountain biota and ecosystem processes.
Temperature trends in most Himalayan regions substantially exceed the global mean trend of 0.85 °C between 1880 and 2012, with winter season temperature trends being generally higher than those of other seasons. Precipitation patterns are spatio-temporally differentiated, but show rather decreasing than increasing trends, in particular during summer. On average, glacier mass budgets have been negative for the past five decades, with glaciers in the Himalaya and in the Hindu Kush showing distinct mass losses, while those in the Karakoram are close to balance. Shrinking rates are regionally variable, but often accelerating, corresponding approximately to a W-E gradient of increasing glacier retreat. Biotic responses to current climate change include elevational range shifts of species, intense recruitment of tree species in treeline ecotones and shifts in phenology, resulting in modified structure, composition and functioning of Himalayan ecosystems.
Udo Schickhoff, R. B. Singh, Suraj Mal

Climate Change

Frontmatter
Chapter 2. Recent Climate Change over High Asia
Abstract
Though elevated regions have generally been spotted as climate change hotspots due to amplified signal of change observed over recent decades, such evidence for the Tibetan Plateau and its neighboring regions is supported only by a sparse observational network, less representative for the high-altitude regions. Using a larger database of widely used gridded observations (CRU and UDEL) and reanalysis datasets (NCEP-CFSR, ERA-Interim, and its downscaled variant ERA-WRF) along with high-quality homogeneous station observations, we report recent changes in mainly the mean monthly near-surface air temperature and its elevation dependence, as well as changes in precipitation over the Tibetan Plateau, its neighboring mountain ranges, and the basins of major rivers originating from them. Our station-based analysis suggests a well-agreed warming over and around the Tibetan Plateau, which is more pronounced mainly during winter and spring months and generally in agreement but higher in magnitude than that of previously reported. We found a varying skillset of considered gridded and reanalysis datasets in terms of suggesting robust spatial and elevation-dependent patterns of trends and their magnitudes. The UDEL, ERA-Interim, and CRU datasets, respectively, exhibit high- to medium-level agreement with the station observations in terms of their trend magnitudes, which are generally underestimated. We found that all datasets agree with station observations as well as among each other for a strongest warming and drying in March over the northwestern region, for wet conditions in May over the southeastern Tibetan Plateau and Myanmar regions, as well as for the general warming pattern. Similarly, a strongest EDW rate per 1000 m elevation found in January is well agreed qualitatively among all datasets, except ERA-WRF. We also confirm high inter-dataset agreement for higher warming rates for highlands (above 2000 m asl) as compared to lowlands in December and January and with a mild agreement during the growing season (April–September). Except for winter months, NCEP-CFSR reanalysis largely contradicts the elevation-dependent warming signal. Our findings suggest that well-agreed likely changes in the prevailing climate will severely impact the geo-ecosystems of the High Asia and will have substantial influence on almost all dimensions of life in the region.
Shabeh ul Hasson, Lars Gerlitz, Udo Schickhoff, Thomas Scholten, Jürgen Böhner
Chapter 3. Analytic Comparison of Temperature Lapse Rates and Precipitation Gradients in a Himalayan Treeline Environment: Implications for Statistical Downscaling
Abstract
High mountain regions have been identified as a major hotspot of climate change during recent decades, resulting in a rapid change of local geo- and ecosystems. The ecosystem response to changes of near-surface temperatures and precipitation is often analyzed and simulated by means of statistical or process-based modeling applications. However, these models require high-quality climate input data. Based on the assumption that freely available gridded climate data sets are often not suitable for climate change impact investigation due to their low spatial resolution and a lack of accuracy, this paper aims to suggest adequate statistical downscaling routines in order to facilitate the cooperation of climate and climate impact research. We firstly summarize the requirements of ecological climate impact studies and identify the deficiencies of freely available climate reanalysis and regionalization products. Based on a network of seven recently installed weather stations in the highly structured target area, the seasonal, diurnal, and spatial heterogeneity of near-surface temperatures and precipitation amounts is analyzed, and the major large-scale atmospheric and local-scale topographic forcing are specified. The analysis of observations highly suggests that local-scale climatic conditions are influenced by both large-scale atmospheric parameters and topographic characteristics. Based on related studies in similar environments, we eventually suggest a statistical downscaling approach integrating large-scale atmospheric fields (derived from reanalysis products or large-scale climate models) and GIS-based terrain parameterization in order to generate fully distributed fields of ecologically relevant climate parameters with high spatial resolution.
Lars Gerlitz, Benjamin Bechtel, Jürgen Böhner, Maria Bobrowski, Birgit Bürzle, Michael Müller, Thomas Scholten, Udo Schickhoff, Niels Schwab, Johannes Weidinger
Chapter 4. Climate Change and Hydrological Responses in Himalayan Basins, Nepal
Abstract
Studies on water and related fields are vital for protecting the environment and climate. Lack of hydrometeorological data, particularly in a high-altitude region such as Nepal, hinders the process of understanding the systems of earth science dynamics. In this study, observed data were used for the period 1988–2010 from three high-altitude regions, viz., Annapurna, Langtang, and Khumbu, of Nepal. The Coupled Global Climate Model (CGCM3) for A1B SRES scenarios during the period 2001–2060 was used to determine projections. The statistical downscaling model (SDSM) was used to downscale precipitation and temperature data at the Modi, Langtang, and Dudh Koshi river basins. The simulated precipitation and temperature data were corrected for bias before implementation in the conceptual rainfall–runoff model Hydraologiska Byrans Vattenbalansavde (HBV) for hydrological response analysis. In the HVB-light 3.0, the Groups Algorithms Programming (GAP) optimization approach and calibration were used to obtain several parameter sets that were ultimately reproduced to observe the stream flow.
The CGCM3 model projects increasing trends in annual as well as seasonal precipitation, except in summer [June, July August, September (JJAS], during 2001–2060 for A1B SERS emission scenarios over the three sites under investigation. The model projects warmer days in every season of the entire period from 2001 to 2060. These warming trends are higher in maximum than in minimum temperatures throughout the year, which indicates an increasing trend of daily temperature range as the greenhouse effect increases. Further, trends for post-monsoon (ON) temperature are much cooler compared to the remaining three seasons (months) over all three sites. In addition, decreasing trends in summer discharge at Langtang Khola and increasing trends in Modi Khola and Dudh Koshi river basins are evident. Among all basins, the flow regime is more pronounced during the later parts of future decades as compared to the preceding decades.
Tirtha Raj Adhikari, Lochan Prasad Devkota
Chapter 5. Spatial and Temporal Variability of Climate Change in High-Altitude Regions of NW Himalaya
Abstract
The high mountain areas such as the Alps, the Rockies, the Himalaya, etc. are considered as the “hotspots” over the surface of the earth where impacts of climate change are likely to be felt significantly. With regard to the Himalaya, their vulnerable ecosystem appears to have reacted to even the slightest possible changes in the temperature and precipitation conditions. The cascading effects of these changes on the vast expanse of water existing in the form of glacier ice and snow in the Himalaya, the forest cover, the health, and the socioeconomic conditions of the population inhabiting the Indo-Gangetic Plains have been the issues of serious concern.
The analyses of the temperature data collected manually at different observatories during the period from 1866 to 2012 show significant rate of warming during the winter season (1.4 °C/100 years) than the monsoon temperature (0.6 °C/100 years), due to rapid increase in both the maximum and minimum temperatures, with the maximum increasing much more rapidly. Annual rate of warming (1.1 °C/100 years) is abnormally higher than the global rate (about 0.7 °C/100 years) during this period. Not all regions of the north-western Himalaya (NWH) have reacted uniformly to the specter of climate change. Studies have confirmed significant spatial and temporal variations in magnitude of winter as well as summer warming in different ranges. While the windward side of the Pir Panjal and parts of the Greater Himalayan and Karakoram Ranges have shown statistically significant winter and summer warming, leeward sides of these ranges have not shown much change. The most remarkable finding of this study is the significant decreasing trend experienced at almost all stations above the equilibrium line (>5300 m in altitude) in winter warming as well as winter precipitation in higher reaches of the Karakoram Himalaya in the last three decades.
From the precipitation point of view, significant decreasing trends (at 95 % confidence level) in the monsoon and overall annual precipitation during the study period are indicated. In contrast, the winter precipitation has shown an increasing but statistically insignificant trend (at 95 % confidence level). Rising winter air temperatures have caused decreasing snowfall component and increasing rainfall component in total winter precipitation on the windward side of the Pir Panjal Range and parts of Greater Himalayan and the Karakoram Ranges. The analyses also show that although winter precipitation in the NWH has remained trendless in the last 140 years, there are significant increasing trends in the extreme snowfall events during winters and rainfall events during summers in Pir Panjal and Shamshawari Ranges in the last three decades and insignificant but increasing trends in the Great Himalayan and Karakoram Range. Decrease in winter snowfall amounts and increasing rainfall component at almost all stations have been affected to some extent by the increase in winter air temperature during this period.
The spatial and temporal variations in winter and summer warming and consequent precipitation changes in different ranges/regions of the NWH are attributed to varying scales of anthropogenic activities and growing urbanization of the areas. Decreasing temperatures in the last three decades in the Karakoram Himalaya with altitudes above the equilibrium line (>5300 m) are attributed to prevalence of permanent snow cover which appears to have influenced their microclimatology. These studies have significant bearing on the mass balance of the glaciers in the region and the hydrological behavior of various river systems in the Himalaya.
M. R. Bhutiyani
Chapter 6. Assessing Climate Change Signals in Western Himalayan District Using PRECIS Data Model
Abstract
The meteorological measurements across Kangra, a western Himalayan district, are examined and analyzed for the past 43 years since 1970 and have been analyzed. Noticeable increase in temperature trends with a considerable variation during different seasons over the past quartile period has been noted. Much perceptible and significant variation among the mean minimum and mean maximum temperature in the northeastern and southwestern part of the district has been brought out. The exchanges between airflow and temperature across the hills, plains, and monsoon may significantly lead to variations in the microclimate. This is essential in predicting global and regional climate variations, because it determines the extent of human influence on the climate and makes sound projections about natural rhythm of changing climate as well as anthropogenic stimulus. The mean monthly maximum and minimum temperature and precipitation together with annual minima and maxima for the period 1970–2013 have been calculated for three stations across Kangra. The differential decadal and annual trend exhibits inconsistent signals of cooling in the high-altitude northeastern block in the district as compared to other parts in the region. Atmospheric Infrared Sounder (AIRS) satellite, Tropical Rainfall Monitoring Mission (TRMM), and Providing Regional Climates for Impacts Studies (PRECIS) data have been considered to analyze the gap.
R. B. Singh, Swarnima Singh, Shouraseni Sen Roy
Chapter 7. Climate Change in Pindari Region, Central Himalaya, India
Abstract
The impending threat due to changing climate has accentuated the vulnerability of all ecosystems. The fragile ecosystems like that of high Himalaya are most susceptible to the climate change which not only disrupts the physical processes but also has its impact on the livelihood of local people. The changes in glaciers have far-reaching impacts on the downstream ecosystems also. In order to prevent the future disastrous events, it becomes necessary to analyze the climatic variability in the region and access the associated vulnerability. The Pindari region is one such example from Himalaya which is under threat due to climate change and represents clusters of glaciers comprising the main Pindari Glacier as trunk part. Pindari Glacier is a small valley-type glacier of Kumaon Himalaya, situated at an elevation 5200 m. The study is based on the medium-resolution monthly average temperature and rainfall data obtained from the India Meteorological Department for the Pindari region from year 1901 to 2010. The results show that the annual temperature has substantially increased by around 1 °C from 1901 to 2010. All seasons in the Pindari region indicate no significant increase in rainfall. A study of data illustrates that the main trunk of the Pindari Glacier has been in a continuous state of recession during the past century.
R. B. Singh, Santosh Kumar, Ajay Kumar

Climate Change Impacts on Glaciers and Hydrology

Frontmatter
Chapter 8. Glacier Variations in the Trans Alai Massif and the Lake Karakul Catchment (Northeastern Pamir) Measured from Space
Abstract
Glacier area and length changes were measured in the central Trans Alai of the northeastern Pamir, including the entire catchment of Lake Karakul. Annual shrinkage determined from Landsat 7 ETM+ imagery accounted for −0.8 ± 0.4 % aˉ1, corresponding to −8.8 ± 4.8 % from 1455 ± 51 km2 in 2000 to 1327 ± 48 km2 in 2011. Several glaciers could be mapped back to 1973 based on a KH-9 Hexagon reconnaissance image. Measured glacier extents of 550 ± 10 km2 in 1973, 540 ± 9 km2 in 2000, and 521 ± 9 km2 in 2011 indicate accelerated shrinkage for the last decade in the Trans Alai. Glaciers retreated on average by −4.3 ± 0.5 m aˉ1 before 2000 and subsequently advanced by +6.1 ± 1.0 m aˉ1 until 2011. Geodetic mass balances of four selected glaciers were determined from a Digital Elevation Model extracted from a 2010 ALOS-PRISM tri-stereo image and the February 2000 SRTM-3 elevation dataset (1999). Its difference image reveals highly variable glacier elevation changes. While three glaciers showed probably a minor loss (−0.16 ± 0.68 m w.e. aˉ1 to −0.06 ± 0.68 m w.e. aˉ1), a more pronounced mass loss was observed for Uisuu Glacier (−0.50 ± 0.68 m w.e. aˉ1). This study reveals significant glacier variations and numerous indications of surges in the Trans Alai, a well-known phenomenon in the Pamir.
Nicolai Holzer, Tim Golletz, Manfred Buchroithner, Tobias Bolch
Chapter 9. Heterogeneity in Fluctuations of Glacier with Clean Ice-Covered, Debris-Covered and Proglacial Lake in the Upper Ravi Basin, Himachal Himalaya (India), During the Past Four Decades (1971–2013)
Abstract
Comprehensive multi-temporal observations of Himalayan glaciers during the past half century indicate the continuous shrinkage of most of the glaciers. In addition to this, the present study analyses the fluctuations of glacier with clean ice-covered, debris-covered and proglacial lake in the upper Ravi basin, Himachal Himalaya (India), from 1971 to 2013 using high-resolution satellite datasets with supplement of field observations for selected glaciers. The study reveals the heterogeneity in fluctuations of glacier as higher terminus and frontal area change for the clean ice-covered glaciers compared to debris-covered glaciers. Field measurements for selected glaciers also suggest a retreating trend and validate the measured glacier changes using remotely sensed temporal data. Glacier retreat rates especially for debris-covered glaciers in the Ravi basin were lower than previously reported for selected glaciers in the similar basin and other basins of the Himachal Himalaya.
Pritam Chand, Milap Chand Sharma, Ram Nagesh Prasad
Chapter 10. Current and Future Glacial Lake Outburst Flood Hazard: Application of GIS-Based Modeling in Himachal Pradesh, India
Abstract
Most studies concerning the hazard from glacial lake outburst floods have focused on the threat from lakes that have formed over the past century, some of which have demonstrated significant growth in response to recent warming of the climate system. However, attention is shifting toward the anticipation of future hazard and risk associated with new lakes that will develop as glaciers continue to retreat and water accumulates within depressions in the exposed bed topography. Using the Indian Himalayan state of Himachal Pradesh as a case study, this chapter provides both a review and implementation of modern approaches to assess current and future glacier lake outburst flood hazard over large spatial scales. Across Himachal Pradesh, the formation of new lakes over the next decades will lead to a minimum two- to threefold increase in land area affected by potential lake outburst floods in several districts. Generally the potential increase in glacial lake outburst flood frequency is demonstrated to be even greater, owing to the heightened opportunity for ice or rock avalanches to impact into larger and more numerous glacial lakes. Methods described herein allow early anticipation of future threats, providing a scientific basis for sound adaptation and planning responses.
Simon K. Allen, Andreas Linsbauer, Christian Huggel, S. S. Randhawa, Yvonne Schaub, Markus Stoffel
Chapter 11. Estimating Recent Glacier Changes in Central Himalaya, India, Using Remote Sensing Data
Abstract
Changing glacier snout positions, surface area, and mass balance are considered as important indicators of climate change. Climatic warming and cooling are reflected through shrinkage and expansion of glaciers, often without significant time lags. Glaciers are important sources of water supply for lowlands and thus have significant influence on ecosystem services, agriculture, and socioeconomic conditions. The economy of the Indo-Gangetic Plain is particularly vulnerable in this respect. Therefore, the present study assesses recent changes (2001–2013) of glaciers in central Himalayan region using remote sensing data. A total of 31 glaciers were mapped on Landsat ETM+ (2001) and OLI (2013) and compared to estimate the changes in snout positions. The study reveals that there are significant variations in glacier retreat. The retreat rate varies between 5.6 m−1 (Lawan Glacier) and about 35.6 m−1 (Pachu Glacier). A total of 6 glaciers retreated with less than 10 m−1, 16 between 10 and 20 m−1, 6 between 20 and 30 m−1, and 3 more than 30 m−1. An attempt has also been made to assess underlying driving forces of the varying retreat rate of glaciers. The elevation of snouts, the area, and the length of glaciers have implications on snout retreat rate. There are, however, some other important factors, e.g., accumulation area ratio, slope angles of accumulation and ablation, amount of rainfall and snowfall, temperature conditions, and debris cover, that have significant bearings on glacier retreat.
Suraj Mal, R. B. Singh, Udo Schickhoff
Chapter 12. Instability Processes Triggered by Heavy Rain in the Garhwal Region, Uttarakhand, India
Abstract
On 16 and 17 June 2013, high-intensity rainfall (>400 mm) in different parts of the state of Uttarakhand caused devastating flash floods and triggered widespread landslides incurring heavy losses to the infrastructure, agricultural fields, human and animal lives, roads and widespread destruction of natural resources. Such a magnitude of disaster was perhaps not witnessed by the region at least over the last 100 years. Thus, this disaster can be considered as an extreme climatic event of the century. The extent and intensity of the tragedy can easily be visualised by the fact that all the famous shrines of the Uttarakhand state, located in high mountainous, snow-bound areas such as Badrinath (3133 m asl on Alaknanda River), Kedarnath (3584 m asl on Mandakini River), Gangotri (3140 m asl on Bhagirathi River), Yamunotri (3291 m asl on Yamuna River) and Hemkund Sahib (4433 m asl on Alaknanda River), were badly affected by this extreme fury of the nature.
Manish Mehta, D. P. Dobhal, Tanuj Shukla, Anil K. Gupta
Chapter 13. The Need for Community Involvement in Glacial Lake Field Research: The Case of Imja Glacial Lake, Khumbu, Nepal Himalaya
Abstract
This chapter explores the relationship between research on glacial lake outburst floods (GLOFs), a lack of communication of results, and resultant confusion among local inhabitants. First, this chapter reviews the progress of research on Imja Glacial Lake (Imja Tsho) in the Mt. Everest region of Nepal, one of the most extensively studied lakes in the Himalaya and which is considered by some to be among the most dangerous lake. Secondly, the lack of community involvement in Imja Glacial Lake research since studies began in the late 1980s is covered, followed by a discussion of the confusion that communities have felt as a result of conflicting opinions regarding the lake’s actual risk of flooding. Thirdly, we argue for the need of a “science-based, community-driven” approach to glacial lake and other climate change research in the interests of finding meaningful and effective solutions to contemporary problems. Developing a new framework of research, community involvement, and action will be important not only for local communities but also for scientists in GLOF-prone areas of the Himalaya as well as elsewhere in the world.
Teiji Watanabe, Alton C. Byers, Marcelo A. Somos-Valenzuela, Daene C. McKinney
Chapter 14. Understanding Factors Influencing Hydro-climatic Risk and Human Vulnerability: Application of Systems Thinking in the Himalayan Region
Abstract
The Uttarakhand flash floods of 2013 have been dubbed as the “Himalayan Tsunami”. The region has been subjected to severe changes in its high-mountain glacial environment. The risk of disasters striking this region has therefore considerably increased in recent times because of the increased human activities and unplanned urbanization, which along with changing climate affects the fragile social-ecological system (SES) in the region. This chapter deals with the study of the SES wellbeing in the Himalayas in light of the 2013 Uttarakhand disaster with focus on the drivers and the interrelationships among them. Systems thinking (ST) is the foundation of the proposed framework for this case study. Application of ST principles provides insights to the way environment has been responding to the stimuli. ST approaches provided the scope to confirm that drivers and dimensions like population, anthropogenic induced disturbances (deforestation and hydel projects) and education (disaster preparedness) need to be given priorities for addressing the challenges. The case of Uttarakhand in India indicates that the systemic behaviour for measuring SES wellbeing can be measured through standard dimensions. However, systematic behaviour analysed through events and pattern analyses, causal-loop diagrams and circular referencing loops provided deeper insights that have differently influenced this systemic behaviour.
Gourav Misra, Harekrishna Misra, Christopher A. Scott

Climate Change and Vegetation Dynamics

Frontmatter
Chapter 15. Climate Change and Treeline Dynamics in the Himalaya
Abstract
Treelines are sensitive to changing climatic conditions, in particular to temperature increases, and the majority of global alpine treelines has shown a response to recent climate change. High temperature trends in the Himalaya suggest a treeline advance to higher elevations; it is largely unknown, however, how broader-scale climate inputs interact with local-scale factors and processes to govern treeline response patterns. This paper reviews and synthesizes the current state of knowledge regarding sensitivity and response of Himalayan treelines to climate warming, based on extensive field observations, published results in the widely scattered literature and novel data from ongoing research of the present authors.
Palaeoecological studies indicate that the position of Himalayan treeline ecotones has been sensitive to Holocene climate change. After the Pleistocene-Holocene transition, treelines advanced in elevation to a position several hundred metres higher than today under warm-humid conditions and reached uppermost limits in the early Holocene. Decreasing temperatures below early and mid-Holocene levels induced a downward shift of treelines after c. 5.0 kyr BP. The decline of subalpine forests and treeline elevation in the more recent millennia was coincident with weakening monsoonal influence and increasing anthropogenic interferences.
To assess current treeline dynamics, treeline type, treeline form, seed-based regeneration and growth patterns are evaluated as sensitivity indicators. Anthropogenic treelines are predominant in the Himalaya; upslope movement of these treelines is related to the effects of land-use change. Near-natural treelines, rare nowadays, are usually developed as krummholz treelines which are relatively unresponsive. Strong competition within the krummholz belt and dense dwarf scrub heaths further upslope largely prevents the upward migration of tree species and retards treeline advance to higher elevation. However, intense recruitment of treeline trees within the treeline ecotone and beyond indicates beneficial preconditions for future treeline ascent. Growth patterns of treeline trees are particularly sensitive to higher winter and pre-monsoon temperatures, suggesting that moisture supply in the pre-monsoon season might be an effective control of future treeline dynamics. Modelled upslope range expansions of treeline trees point to potentially favourable bioclimatic conditions for an upward shift of treelines.
Udo Schickhoff, Maria Bobrowski, Jürgen Böhner, Birgit Bürzle, Ram Prasad Chaudhary, Lars Gerlitz, Jelena Lange, Michael Müller, Thomas Scholten, Niels Schwab
Chapter 16. Treeline Responsiveness to Climate Warming: Insights from a Krummholz Treeline in Rolwaling Himal, Nepal
Abstract
At a global scale, the elevational position of natural upper treelines is determined by low temperatures during growing season. Thus, climate warming is expected to induce treelines to advance to higher elevations. Empirical studies in diverse mountain ranges, however, give evidence of both advancing alpine treelines as well as rather insignificant responses. Himalayan treeline ecotones show considerable differences in altitudinal position as well as in physiognomy and species composition. To assess the sensitivity of a near-natural treeline to climate warming at local scale, we analysed the relations between changes of growth parameters and temperature gradients along the elevational gradient in the treeline ecotone in Rolwaling valley, Nepal, by a multispecies approach. We observed species-specific transition patterns (diameter at breast height, height, tree and recruit densities) and varying degrees of abruptness of these transitions across the treeline ecotone resulting in a complex stand structure. Soil temperatures are associated with physiognomic transitions, treeline position and spatial regeneration patterns. In conclusion, treeline tree species have the potential to migrate upslope in future. Upslope migration, however, is controlled by a dense krummholz belt of Rhododendron campanulatum. Currently, the treeline is rather stable; however we found a prolific regeneration as well as signs of stand densification. Given the spatial heterogeneity of Himalayan treeline ecotones, further studies are needed to fully understand the complex conditions for the establishment and development of tree seedlings and the responsiveness of Himalayan treeline ecotones to climate change.
Niels Schwab, Udo Schickhoff, Michael Müller, Lars Gerlitz, Birgit Bürzle, Jürgen Böhner, Ram Prasad Chaudhary, Thomas Scholten
Chapter 17. Dendroecological Perspectives on Climate Change on the Southern Tibetan Plateau
Abstract
Tree rings are indicators of historic environmental changes and plant response to past and current climate change. Summer temperature reconstructions from maximum latewood density on the southeastern Tibetan plateau (TP) for the past 600 years revealed cool summer temperatures between ca. 1580 and 1790 A.D., corresponding to the “Little Ice Age (LIA).” This period was characterized by several glacier advance periods, with a maximum glacier extent ending around 1740–1780 A.D. and smaller readvance phases during the early nineteenth to late nineteenth century. Stable carbon isotope analyses of tree-ring cellulose indicate species-specific ecophysiological response patterns of trees to environmental conditions related to enhanced atmospheric CO2 levels and drier site conditions which might affect future forest composition. Spatial patterns of altitudinal changes of climate-growth relationships indicate the dominance of different growth-limiting factors in different regions of the TP. In semiarid regions along the western distribution limit of forests, moisture availability during the growing season is most relevant for growth of juniper tree species even in high altitudes. In contrast, warmer temperatures have a stimulating effect on radial growth close to the upper tree limit on the humid eastern TP. These findings are corroborated by first studies of cambial phenology, indicating a stimulating influence of early growing season temperatures on cell formation. In the dry northeastern TP, wet conditions during the main growing season in June are favorable for radial growth. Due to the low number of studies and a long history of human impact on forests, a climate-driven upward shift of the upper tree limit cannot yet clearly be stated. Tree-ring analyses on long-living dwarf shrubs may increase the potential for dendrochronological climate reconstructions beyond the upper limit of tree growth on the TP.
Achim Bräuning, Jussi Grießinger, Philipp Hochreuther, Jakob Wernicke
Chapter 18. Spatially Variable Vegetation Greenness Trends in Uttarakhand Himalayas in Response to Environmental Drivers
Abstract
Over the last few decades, Western Himalayas experienced high population growth and increase in exploitative land use practices. This trend coupled with influence of climatic variability has resulted in significant negative effects on vegetation cover and productivity. This study aims to understand the spatial patterns and severity of these impacts in Uttarakhand Himalayas. Specifically, the objectives of this study are twofold: first, to quantify interannual trends in vegetation greenness by conducting nonparametric Mann-Kendall trend analysis on MODIS-NDVI time series (2000–2014) and, second, to assess distribution of this trend with respect to land use land cover properties and elevation zones. The results show that out of the total vegetated area in Uttarakhand, 2,686.95 km2 (5.69 %) showed changes in the vegetation greenness and 73.64 % of this change was significant negative trend (browning). While areas with <800 m elevation showed dominant browning, those between 800 and 1600 m showed significant positive trend (greening), and majority of areas >1600 m were characterized by browning trend. Majority of intensively cultivated irrigated croplands in the Himalayan foothills and areas around growing urban centers showed widespread browning, whereas areas of rainfed cultivation showed dominant greening. Browning was also dominant in closed needle leaf forests and alpine shrublands, except areas where human impacts has led to more mixed patterns. These results highlight previously unreported fine-scale spatial variations in vegetation productivity trend with respect to both elevation and LULC properties.
Niti B. Mishra, Gargi Chaudhuri
Chapter 19. Impact of Glacial Recession on the Vegetational Cover of Valley of Flowers National Park (a World Heritage Site), Central Himalaya, India
Abstract
With the growing threat of global warming, it has been projected that the Himalayan ecosystem will be severely affected. However, the nature and the magnitude of this ecosystem response are still elusive. Although the entire Himalayan region is prone to climatic perturbation, the high-altitude terrain is considered to be most fragile because of the presence of the microclimatic domain sustained by glaciers and snow line fluctuation (both long term and short term). Our recent observations in one of the most sensitive valleys of the Himalaya, the Valley of Flowers National Park, have shown that during the past 46 years the main Tipra valley glacier has receded 535 m. As a consequence, vegetation has appeared to occupy the vacated area. For the first time, three montane warm-loving species, Pinus wallichiana A.B. Jackson [at 3865 m above sea level (a.s.l.)], Picea smithiana (at 3700 m asl) (Wall.) Boiss., and Populus ciliata Wall. ex Royle (at 3712 m asl), have shown upward migration from the established altitudes of 2500 to 3800 m asl, from 2700 to 3700 m asl, and from 3000 to 3700 m, respectively. These observations are the very first suggesting that the alpine ecosystem has begun to respond to changes in temperature and precipitation during the past 50 years.
M. P. S. Bisht, Virendra Rana, Suman Singh
Chapter 20. Snow Cover Dynamics and Timberline Change Detection of Yamunotri Watershed Using Multi-temporal Satellite Imagery
Abstract
This paper is an attempt to examine the impact of climate change over snow cover and timberline dynamics in the alpine zone of Yamunotri watershed in the Garhwal Himalaya. The study extracts dynamics of snowline and timberline using Landsat TM data of two different time periods, i.e. 1990 and 2010. Temporal images of study area were processed in the GIS environment using Normalized Difference Snow Index (NDSI) and Normalized Difference Vegetation Index (NDVI) algorithm on ERDAS Imagine and ArcGIS 9.3. To determine the height of the snow and timberline, Shuttle Radar Topographic Mission (SRTM) data was used. The result reveals that the snow cover in 1990 was estimated at 707 km2 which decreased to 552 km2 in 2010. The average height of timberline in Yamunotri watershed was 3580 m in the year 1990 and 3660 m in 2010, while the average height of snowline was 4480 m in 1990 and 4660 m in 2010. These data suggest that due to global warming the timberline in the alpine zone has been shifted towards higher elevation at an average rate of 4 m/year during the last 20 years (i.e. 1990–2010). The snowline has also shifted towards higher elevation at an average rate of 9 m/year. During this period, about 68.58 km2 non-timber areas of the alpine zone were converted into timber area at an average rate of 3.42 km2/year, while during the same period, about 155 km2 snow cover areas were converted into non-snow cover area at an average rate of 7.75 km2/year.
Manish Kumar, Pankaj Kumar
Metadaten
Titel
Climate Change, Glacier Response, and Vegetation Dynamics in the Himalaya
herausgegeben von
RB Singh
Udo Schickhoff
Suraj Mal
Copyright-Jahr
2016
Electronic ISBN
978-3-319-28977-9
Print ISBN
978-3-319-28975-5
DOI
https://doi.org/10.1007/978-3-319-28977-9