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FS 3.129

Responses of Mountain Ecosystems in Asia to recent climate change

Session status: Accepted
Content last updated: 2025-08-26 09:04:26
Online available since: 2025-01-13 20:52:36

Details

  • Full Title

    FS 3.129: Responses of Mountain Ecosystems in Asia to recent climate change
  • Scheduled

    Talks:
    2025-09-18, 08:30 - 10:00 (LT), Theologie – HS 1
    Talks:
    2025-09-18, 08:30 - 10:00 (LT), Theologie – HS 1
  • Co-Convener(s)

    Bräuning, Achim
  • Assigned to Synthesis Workshop

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  • Thematic Focus

    #IMC25, 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.

Registered Abstracts

Date/time indicate the presentation; if available: the bracketed duration is added for end-of-presentation Q&A.
ID: 3.8392
Talk/Oral
|Wang, Lu
Presentation Location Theologie – HS 1
|
2025-09-18 08:30 - 08:38 (+2min)

Wang, Lu
Responses of Mountain Ecosystems in Asia to Recent Climate Change: Insights from Tree Growth and Soil Moisture Dynamics on the Southeastern Tibetan Plateau
Wang, L.
Wang, L.; Liu, H.; and Jussi, J.
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: 3.11531
Talk/Oral
|Foroozan, Zeynab Parisa
Presentation Location Theologie – HS 1
|
2025-09-18 08:40 - 08:48 (+2min)

Foroozan, Zeynab Parisa
Hydroclimate Insights from Juniper Tree Rings in Iran’s Mountain Ecosystems
Foroozan, Z. P.
Mazaherifar, M. H.; Aryal, S.; Pourtahmasi, K.; and Bräuning, A.
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: 3.12043
Talk/Oral
|Huang, Ru
Presentation Location Theologie – HS 1
|
2025-09-18 08:50 - 08:58 (+2min)

Huang, Ru
Frequency-dependent Climate Signals of Tree-ring Oxygen Isotopes in the western Kunlun and Karakoram Mountains
Huang, R.
Zhu, H.; Liang, E.; Jens-Henrik Meier, W.; Asad, F.; and Grießinger, J.
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: 3.13010
Talk/Oral
|Maharjan, Amrit
Presentation Location Theologie – HS 1
|
2025-09-18 09:00 - 09:08 (+2min)

Maharjan, Amrit
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)
Maharjan, A.
Schwab, N.; Böhner, J.; Scholten, T.; Chaudhary, R. P.; Adhikari, R.; Subedi, C. K.; and Schickhoff, U.
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: 3.13326
Talk/Oral
|Bräuning, Achim
Presentation Location Theologie – HS 1
|
2025-09-18 09:10 - 09:18 (+2min)

Bräuning, Achim
Tree-ring evidence of glacier retreat since the Little Ice age and its climatic control on the Tibetan Plateau
Bräuning, A.
Grießinger, J.; Wernicke, J.; and Zhu, H.
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.