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FS 3.129

Responses of Mountain Ecosystems in Asia to recent climate change

Details

Full Title
FS 3.129: Responses of Mountain Ecosystems in Asia to recent climate change
Scheduled
TBA
Location
TBA
Convener
Jussi Grießinger
Co-Conveners
Achim Bräuning,
Assigned to Synthesis Workshop
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Thematic Focus
Ecosystems, ES-Forests
Keywords
Asian Mountains, Mountain ecosystems, Adaptation and Resilience, Climate Change

Description

Across the region of the Asian mountain systems, climate change is already severely affecting (geo)ecosystems in multiple ways. A pronounced temperature increase within the past decades and enhanced hydroclimatic variability, including monsoon failures and drought periods, but also an increase of extreme precipitation events and relate flooding are some of the major impacts significantly affecting the geosphere, cryosphere and biosphere. The resulting environmental changes have already impacted the local hydrological systems and in turn are altering and will further alter local ecosystems. Examples include challenges for Asian forest ecosystems by various environmental stressors, and a massively changing hydrology in the vicinity of glaciers and their forelands. Following recent climate projection scenarios, such effects will further aggravate in future, posing dramatic challenges also to local livelihoods. This session is seeking contributions dealing with the direct and indirect effects of climate change on mountain ecosystems in Asia, including mountain forests, tree line dynamics, shrub encroachment, and alpine vegetation. Relevant ecosystem responses include changes in growth response and biomass accumulation, shrinkage or extension of species or ecosystem ranges, and modified fluxes of water, carbon, and nutrients. Beside responses on the species and ecosystem level, also responses on the individual plant level may be addressed, that provide indications of adaptations or responses to changing environments, including variations of morphological or ecophysiological traits of affected organisms.

Submitted Abstracts

ID: 3.8392

Responses of Mountain Ecosystems in Asia to Recent Climate Change: Insights from Tree Growth and Soil Moisture Dynamics on the Southeastern Tibetan Plateau

Lu Wang
Wang, Lu; Liu, Hongyan; Jussi, Jussi

Abstract/Description

Mountain ecosystems in Asia are highly sensitive to climate change, with shifts in temperature, precipitation, and soil moisture exerting profound effects on vegetation growth and ecological stability. This study integrates long-term soil moisture reconstruction and tree physiological responses to assess recent changes in mountain forest ecosystems on the southeastern Tibetan Plateau. Using a three-century-long tree-ring δ18O-based soil moisture reconstruction, we identify an abrupt wet-to-dry transition in 1884, followed by a declining trend and enhanced variability, with dry summers occurring more frequently since the 1950s. These changes are primarily driven by weakened monsoonal precipitation rather than temperature increases, highlighting the dominant role of hydrological shifts in shaping ecosystem responses. Additionally, we examine the divergent growth responses of two coexisting conifer species, Juniperus tibetica and Picea balfouriana, to rising atmospheric CO₂ and climate variability. Tree-ring width and dual-isotope (δ13C and δ18O) analyses reveal that juniper growth has been stimulated by increased intrinsic water-use efficiency (iWUE), while spruce growth remains constrained by moisture availability. Despite similar iWUE increases (22% for juniper, 26% for spruce) from 1954 to 2007, spruce growth is more sensitive to soil moisture than temperature, underscoring the limitations of CO₂ fertilization effects in moisture-limited environments. These findings emphasize the critical influence of hydrological changes on mountain forest resilience, with implications for predicting future ecosystem responses under ongoing climate change.

ID: 3.10547

An overview of climate-growth response of multiple tree species from Nepal Himalaya

Narayan Gaire
Dhakal, Yub Raj; Shah, Santosh K.; Grießinger, Jussi; Fan, Ze-Xin; Aryal, Sugam; Bräuning, Achim

Abstract/Description

Himalayan region, also known as third pole, is vulnerable to the ongoing climate change as the region is experiencing rapid warming, increase in extreme temperature and precipitation, frequent and intense droughts affecting the diverse bio-physical sectors. However, there is still a knowledge gap on how the increasing extreme climate, especially droughts, is affecting the growth and sensitivity of the diverse forest trees of the region. Similarly, there is paucity of information about the quantitative annual growth of diverse tree species in response to climate change. Therefore, a comprehensive dendrochronological study was conducted based on a network of more than 100 tree-ring chronologies from Central (Nepal) Himalaya. Growth statistics revealed that the mean and maximum annual radial growth rate and mean sensitivity decreased with increasing elevations while expressed population signal, R-bar and first order autocorrelation increased with increasing elevation. Temporal trend of tree-ring chronologies revealed both positive and negative growth trends during the 20th century reflected in terms of topographic as well as within and between tree species variability. Study found that warm but dry late winter and spring seasons could result locally missing rings in the trees growing in the Nepal Himalaya. Tree-growth climate relationships revealed species-specific as well as some geographical patterns in the climatic responses. Trees from western part of the Nepal Himalaya are more moisture or drought sensitive, while trees from the eastern and central part and from high elevations are more sensitive to temperature change. Favorable spring season climate is very important for the growth of the majority of the species in the region. In the warming but drying anticipated future, climate change in the Himalayan region can affect tree species in diverse ways ultimately impacting the overall ecosystem services provided by them.

ID: 3.11244

Greening thanks to or despite warming? Unraveling climate constraints to Ladakh’s cold desert plant growth.

Martin Macek
Kopecký, Martin; Wild, Jan; Prošek, Jiří; Jandová, Veronika; Doležal, Jiří

Abstract/Description

Plant growth in the cold deserts of the Himalayan region of Ladakh is limited by both low temperatures and low water availability. While rising temperatures prolong the growing season, they also alter water availability through increased evapotranspiration or earlier snowmelt. The response of vegetation to a changing climate in this region depends on the balance between the positive effects of a prolonged growing season and accumulated heat, and the altered water regime. Using combined evidence from micro-scale in-situ observations and experiments on individual plant growth, as well as satellite-based NDVI, we discuss the role of temperature and precipitation variability in vegetation dynamics along the steep elevational gradients of Ladakh. Our results highlight the prominent limiting role of water availability for plant growth in this region and detect a significant greening trend, independent of climatic drivers.

ID: 3.11531

Hydroclimate Insights from Juniper Tree Rings in Iran’s Mountain Ecosystems

Zeynab Parisa Foroozan
Mazaherifar, Mohammad Hossein; Aryal, Sugam; Pourtahmasi, Kambiz; Bräuning, Achim

Abstract/Description

Mountain ecosystems in Iran are increasingly affected by hydroclimatic extremes, such as severe droughts, flash floods, and enhanced atmospheric moisture deficits intensified by ongoing climate change, low resilience, and high vulnerability. To better understand long-term hydrological variability and its impact on tree growth, we developed a 499-year tree-ring width (TRW) chronology (1523–2021) and a 200-year stable oxygen isotope (δ¹⁸O) record (1821–2020) from Juniperus polycarpos in the high-elevation Hezar Masjed Mountains of northeastern Iran. Using these proxies, we reconstructed the Standardized Precipitation-Evapotranspiration Index (SPEI) and vapor pressure deficit (VPD) for the growing season (March–September) from 1821 to 2020 CE. Our results showed the highest frequency of extreme and moderate soil moisture stress (SPEI) events over the past five decades. An increasing number of dry growing seasons marked by both atmospheric and soil moisture deficits emphasize a shift toward drier conditions. Spatial correlation analysis demonstrates the regional representativeness of the reconstructed series across Iran and neighboring regions, with strong negative teleconnections between reconstructed VPD and gridded March–September vapor pressure across Iran and Central Asia. Superposed Epoch Analysis (SEA) revealed that soil moisture stress (SPEI) is the dominant driver of reduced tree growth, while high VPD alone does not necessarily lead to significant growth reductions. In fact, tree-ring width showed a slight but significant increase in high-VPD years, likely due to compensatory soil moisture conditions or species-specific adaptations. However, when high VPD coincided with low SPEI, growth declined sharply, emphasizing the compounding stress effect of simultaneous atmospheric and soil moisture droughts. Our findings revealed the critical role of soil moisture availability in tree growth resilience and suggest that while trees can tolerate short-term atmospheric droughts, their growth is highly sensitive to prolonged soil moisture deficits. This study underscores the increasing hydroclimatic stress on mountain forest ecosystems in Iran and provides valuable insights for climate adaptation strategies in water-limited environments.

ID: 3.11660

Assessing Climatic Influences on δ¹³C Chronologies of Trees in the Nepal Himalayas

Sugam Aryal
Hannak, Nandini; Gaire, Narayan; Poudel, Ram Chandra; Bhattarai, Tribikram; Bräuning, Achim

Abstract/Description

Stable carbon isotope (δ¹³C) chronologies from tree rings are valuable proxies for reconstructing past climatic and environmental conditions. This study compares two site-specific δ¹³C chronologies of Abies spectabilis from the eastern and central Nepal Himalayas. We examine their coherence, variability, and climatic sensitivity to assess regional differences in the physiological responses of trees to environmental factors. We examined the influence of temperature, precipitation, and atmospheric CO₂ concentration on carbon assimilation processes by analysing isotopic trends over multiple decades. Our results reveal site-specific differences in δ¹³C signatures, likely influenced by local climatic regimes, elevation, and micro-environmental conditions. This study helps to better understand the spatial variability of δ¹³C chronologies in the Himalayas, with implications for climate reconstructions and assessing tree physiological responses to ongoing climatic changes.

ID: 3.12043

Frequency-dependent Climate Signals of Tree-ring Oxygen Isotopes in the western Kunlun and Karakoram Mountains

Ru Huang
Zhu, Haifeng; Liang, Eryuan; Jens-Henrik Meier, Wolfgang; Asad, Fayaz; Grießinger, Jussi

Abstract/Description

Tree-ring oxygen isotopes from the western Kunlun and Karakoram Mountains provide valuable insights into past climate variability in High Asia. Our analysis reveals frequency-dependent climate signals encoded in tree-ring oxygen isotopes. In the western Kunlun Mountains, tree-ring oxygen isotopes primarily reflect summer precipitation and evapotranspiration at lower frequencies, while at higher frequencies, it is strongly correlated with vapor pressure deficit, indicating atmospheric aridity. A similar frequency-dependent pattern emerges in the Karakoram tree-ring oxygen isotopes chronologies, where winter-spring temperatures dominate the low-frequency signals, while summer precipitation drives the higher-frequency variations. Notably, our reconstruction of the low-frequency winter-spring temperature signal reveals unexpectedly warmer conditions during the Little Ice Age (1647–1746) compared to the 20th century. This finding is supported by ice core oxygen isotopes from High Asia and northern North America. We propose that these anomalous conditions may be linked to an eastward shift in the Polar Vortex and strengthened mid-latitude Westerlies over Eurasia.

ID: 3.12743

Do tree ring data reflect contrasting climate sensitivity in a Himalayan treeline ecotone? A comparision of Abies spectabilis (D. Don) and Rhododendron campanulatum (D. Don)

Amrit Maharjan
Schwab, Niels; Böhner, Jürgen; Scholten, Thomas; Chaudhary, Ram Prasad; Adhikari, Rabindra; Subedi, Chandra Kanta; Schickhoff, Udo

Abstract/Description

High-elevation ecosystems are among the most vulnerable to climate change. Climatic treelines are expected to shift to higher elevations due to the tight coupling between treeline position and temperature. However, tree species within treeline ecotones may show diverging sensitivities to changes in temperature and precipitation, resulting in altered competitive relationships and ultimately affecting treeline dynamics. Using a dendroclimatology approach, we compared tree growth-climate relationships of Abies spectabilis and Rhododendron campanulatum, two dominant species of Central Himalayan treeline ecotones. We correlated tree ring widths with monthly and seasonal climate data, including the Standardized Precipitation-Evapotranspiration Index (SPEI). The moving correlation and response function analysis revealed inconsistent tree growth-climate relationships across time. We found contrasting patterns of climate sensitivity: Abies spectabilis exhibited a strong negative response to pre-monsoon season (March-May) temperature, especially in recent decades, potentially linked to increased drought stress as indicated by responses to precipitation and SPEI. In contrast, Rhododendron campanulatum showed growth responses to temperature of all seasons, especially winter (December-February) and late summer (June-August). Signs of drought stress are less pronounced in comparison to Abies spectabilis. Tree growth-climate correlations are more stable over time, indicating greater resilience to climatic variability compared to Abies spectabilis. This difference in climate sensitivity suggests that Abies spectabilis may be more vulnerable to currently changing climate conditions, while Rhododendron campanulatum may be more resilient to climate variability. These findings have important implications for understanding and forecasting the effects of climate change on Himalayan treeline dynamics. A potential expansion of Rhododendron campanulatum expansion relative to Abies spectabilis under predicted warming scenarios could significantly alter the structure and function of Himalayan treeline ecotones.

ID: 3.13010

Do tree ring data reflect contrasting climate sensitivity in a Himalayan treeline ecotone? A comparison of Abies spectabilis (D. Don) Mirb. and Rhododendron campanulatum (D. Don)

Amrit Maharjan
Schwab, Niels; Böhner, Jürgen; Scholten, Thomas; Chaudhary, Ram Prasad; Adhikari, Rabindra; Subedi, Chandra Kanta; Schickhoff, Udo

Abstract/Description

High elevation ecosystems are among the most vulnerable to climate change. Climatic treelines are expected to shift to higher elevations due to the tight coupling between treeline position and temperature. However, tree species within treeline ecotones may show diverging sensitivities to changes in temperature and precipitation, resulting in altered competitive relationships and ultimately affecting treeline dynamics. Using a dendroclimatology approach, we compared tree growth-climate relationships of Abies spectabilis and Rhododendron campanulatum, two dominant species of Central Himalayan treeline ecotones. We correlated tree ring widths with monthly and seasonal climate data including the Standardized Precipitation-Evapotranspiration Index (SPEI). The moving correlation and response function analysis revealed inconsistent tree growth-climate relationships across time. We found contrasting patterns of climate sensitivity: Abies spectabilis exhibited a strong negative response to pre-monsoon season (March-May) temperature, especially in recent decades, potentially linked to increased drought stress as indicated by responses to precipitation and SPEI. In contrast, Rhododendron campanulatum showed growth responses to temperature of all seasons, especially winter (December-February) and late summer (June-August). Signs of drought stress are less pronounced in comparison to Abies spectabilis. Tree growth–climate correlations are more stable over time indicating greater resilience to climatic variability compared to Abies spectabilis. This difference in climate sensitivity suggests that Abies spectabilis may be more vulnerable to currently changing climate conditions, while Rhododendron campanulatum may be more resilient to climate variability. These findings have important implications for understanding and forecasting the effects of climate change on Himalayan treeline dynamics. A potential expansion of Rhododendron campanulatum expansion relative to Abies spectabilis under predicted warming scenarios could significantly alter the structure and function of Himalayan treeline ecotones.

ID: 3.13258

Impact of Climate Change on Vegetation Dynamics in Alpine Ecosystems of the Kumaun Himalaya, Uttarakhand, India

Sarita Palni
Parashar, Deepanshu; Singh, Ajit Pratap

Abstract/Description

Vegetation dynamics serve as key indicators of climate change, particularly in ecologically sensitive regions like the Alpine and Cryospheric zones of the Himalayas. This study examines the spatiotemporal changes in vegetation cover across the Kumaun Himalaya, a part of the Central Himalaya, over a 25-year period (1999–2024), focusing on climate-induced variations. Using remote sensing data, the research assesses vegetation spectral indices, particularly the Normalized Difference Vegetation Index (NDVI), to analyze three key vegetation classes: Grassland, Scrubland, and Forest Cover. A statistical trend analysis is conducted using the Mann-Kendall (MK) test on historical meteorological data (temperature and precipitation) obtained from Power Data Access Viewer datasets. The study aims to (i) conduct a detailed spatiotemporal analysis of vegetation cover, (ii) identify the primary climatic drivers influencing vegetation changes, and (iii) perform a statistical analysis of long-term meteorological trends. Findings indicate significant variations in vegetation cover, with notable fluctuations in NDVI values, reflecting the impact of changing climate conditions. The analysis reveals trends in annual mean minimum-maximum temperatures and annual rainfall, shedding light on their influence on vegetation patterns. The insights from this research will contribute to the sustainable management and monitoring of forests in the alpine ecosystems of the Kumaun Himalaya. The study provides essential data for developing strategies to mitigate the challenges of ongoing climate change in this fragile mountain environment.

ID: 3.13326

Tree-ring evidence of glacier retreat since the Little Ice age and its climatic control on the Tibetan Plateau

Achim Bräuning
Grießinger, Jussi; Wernicke, Jakob; Zhu, Haifeng

Abstract/Description

On the eastern Tibetan plateau (TP), Little Ice Age (LIA) glacier advances reached far below the upper tree line. This provides unique opportunities to study the contact zone of mountain forests and glaciers, to use tree-ring data to provide dating control for glacier history, and utilize tree-ring based climate reconstrutions for the assignment of glacier responses to changes in the temperature and moisture regime. Furhermore, such a setting enables us to study the response of mountain forest ecosystems to coupled impacts of recent climate induced environmental changes. We studied several glacier forefields in a series of mountain ranges, namely Gongga Shan, Hengduan Shan, and the heavily glaciated mountain ranges north of the Yarlung Tsangpo river in the southern TP. Tree age-derived moraine dating revealed a high consistently of minimum ages of maximum LIA glacier advances between CE 1760-1785, although also older glacier morain deposits were found. Moraines of recessional stages date from the early (1820s-1830s) and late (1870s to 188s) 19th century as well as from the early 20th century (1920s). From each glacier system, we analyzed tree-ring oxygen isotope (δ¹⁸O) records, which were used to reconstruct variations in the hydroclimate and maximum latewood density (MXD) as a proxy for summer temperature. The derived summer temperature reconstruction revealed that the temperature depression of ca. 1°C during the LIA maximum (around 1600-1750 CE) provided the background for a general decline in equilibrium line altitude of regional galciers, leading to subsequent glacier advances. δ¹⁸O-baased moisture reconstructions revealed that local glacier advances can be assigned to temporal variations of increased moisture availability. Long-term drying trends of decreased summer monsoon activity as well as multi-decadal moisture variability are widely consistent over the whole study area. However, backward trajectory analyses of climatic extreme event years indicate that differences in air mass origin and therefore moisture regimes are evident in different parts of the southern and eastern TP, ponting to the influence of regional transport pathways influencing forest ecosystems and regional glacier mass balance. If the observed trend of monsoonal activity bility will further continue, we expect a significant impact on Asian high mountain forest ecosystems.

ID: 3.13549

Hydroclimatic Variability and Tree Growth in Northern Pakistan Under Recent Climate Change

Fayaz Asad
Zhu, Haifeng

Abstract/Description

Assessing the effects of climate change requires an understanding of the hydroclimatic variability in mountain ecosystems. This research offers a 586-year tree-ring width (TRW) history of Picea smithiana from the Chara and Naltar valleys in Gilgit-Baltistan, northern Pakistan. Tree growth has a robust positive link with summer precipitation and the Palmer Drought Severity Index (PDSI) (p < 0.01), but a negative correlation is seen with summer temperature, underscoring moisture availability as the principal limiting factor. A reconstruction of summer PDSI (1431–2016 CE) accounts for 35.1% of the observed variation in the calibration period (1956–2016). Significant drought occurrences, such as the Mughal Mega Drought (1630–1670 CE) and recurrent decadal droughts throughout the 18th and 19th centuries, are recognized. Wavelet power spectrum study indicates hydroclimatic variability at inter-annual (2–8 years) and multi-decadal (64–128 years) scales, with recent decades exhibiting heightened inter-annual variations, presumably associated with human climate change. Major climatic factors, including sea surface temperature anomalies in the Indian and Pacific Oceans, profoundly affect regional moisture patterns. The results underscore the vulnerability of high-altitude forests to climate change, offering essential insights for sustainable forest management and adaptation methods in the Himalayas

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#IMC: September 14 - 18 2025

FS 3.129

Responses of Mountain Ecosystems in Asia to recent climate change

Details

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Assigned to Synthesis Workshop

Thematic Focus

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Description

Submitted Abstracts

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