[M-IS01] Environmental, socio-economic, and climatic changes in Northern Eurasia

[MIS01-P06] Shifts in mountain vegetation reveal ecological responses to changing environmental conditions in Central Asian highlands

*Munavar Zhumanova¹, Geoffrey M Henebry^2,1 (1.Center for Global Change and Earth Observations, Michigan State University, 2.Department of Geography, Environment, and Spatial Sciences, Michigan State University)

Keywords:precipitation patterns , vegetation resurvey , mountain pastures , Kyrgyzstan

Mountain pastures feature complex terrain and experience harsh climatic conditions. The resulting vegetation formations are spatially heterogeneous, influenced by slope, aspect, and disturbance history. Studies on changing climate and mountain vegetation dynamics in Central Asia are few. We used nine species ecological indicators and three phytoindicators of environmental conditions to reveal species-specific, community, and landscape-level responses to changes in land use and ecological factors, and to identify limiting factors. Using a resurvey approach, we explored the responses of mountain vegetation communities to environmental changes in the Western Tien-Shan ranges in Kyrgyzstan. We assembled historic vegetation data (1973-1987) for 136 species in six vegetation types and then resurveyed the plots annually from 2008-2019. In response to global warming, mean elevation shifted significantly (p<0.001) for 35 out of 136 species, with 60% shifting >100 m. More species shifted upwards (mainly at lower and higher elevations) than downwards (mainly at mid-elevations). Overall, three patterns of vegetation homogenization within and among ecozones were observed. First, the mountain steppe, meadow-steppe, and subalpine meadows showed the strongest convergence towards the dominance of mesic shrubs, related to increasing precipitation, changing soil moisture, and the transient dominance of mesohalotrophic Iris spp. following changes in soil-salt regimes. Second, in high mountain steppe and alpine ecozones, keystone cushion dwarf shrubs expanded and shifting slightly upwards into areas of permanent snow belt shrinkage. Upward shifts of forbs into grass swards, driven by increased soil moisture from earlier and faster snowmelt but no precipitation changes during the growing season. Third, in the semidesert ecozone, drastic declines in Artemisia communities were linked to downward shifts of transient dominant, tropophytic species (e.g., Prangos, Ferula, Inula) from mid-elevation combined with upward shifts of desert ecozone species (e.g., Alhagi, Aegilops, Koelpinia) linked to highly variable soil moisture availability during spring. Current states of mountain ecosystems in the Western Tien-Shan are likely more mediated by precipitation variability that affects soil properties than warming. Accordingly, observed changes at high elevations may be an ephemeral effect in most cases; once the extent of permanent snow cover and small glaciers have greatly diminished or even totally disappeared, warmth-requiring or drought-tolerant species might expand upslope rapidly. Responses of mountain vegetation to global change may not always be direct: elevational shifts in one vegetation type may induce changes in neighboring vegetation communities. Adaptive management should consider vegetation responses to environmental changes and promote alternative land use options to maintain the productivity and resilience of mountain pastures. Advances in such analyses of combined datasets with remote sensing integration may derive valuable insights for interdisciplinary research groups working on climate change, deglaciation, snow cover loss, hazard, and the resulting ecological impacts in the regional and global context.