About

Karina Yager is an Associate Professor in the Office of the Dean SOMAS Atmospheric Sciences at Stony Brook University. Her research is focused on the social and ecological impacts of climate change in the Andes of South America. Her transdisciplinary approach examines coupled social ecological systems (SES) and land cover land use change (LCLUC) in mountain environments, combining remote sensing analysis, alpine vegetation studies, peatland research, and ethnographic fieldwork with indigenous pastoralists. Her current projects investigate the impact of disappearing tropical glaciers on pastoral agriculture and water resources, as well as deciphering the climate and societal drivers of peatland dynamics and land cover change in the Andes. She has been involved with the GLORIA network in South America since 2002 and her work is funded by organizations such as NASA, CONICYT in Chile, and the National Geographic Society.

Research topics

• Environmental science
• Ecology
• Geography
• Physical geography
• Environmental planning
• Forestry
• Geology
• Cartography
• Agroforestry
• Climatology
• Biology
• Environmental resource management

Selected publications

• Coping with Climate Change: A Mixed-Methods Approach to Understanding Irrigation Technology Outcomes in Gujarat, India

  Socius Sociological Research for a Dynamic World · 2026-03-01

  articleOpen access

  Previous research on climate change interventions highlights that adaptation and mitigation strategies must be tailored to local contexts to effectively benefit both people and the environment. However, there remains a gap in analyzing the effectiveness of locally specific climate-related technologies in enhancing food security, improving livelihoods, and addressing social dimensions such as women’s autonomy. The authors address that gap by drawing on two data sources, one quantitative and one qualitative, to evaluate the impact of an irrigation technology. Specifically, the authors assess its effectiveness in improving crop yields and addressing issues related to migration, women’s autonomy, and economic conditions. The quantitative data come from a 2024 survey of 199 farmers across the Harij, Sami, and Sankheswar blocks of Patan district in Gujarat, India. The qualitative data are based on in-depth interviews conducted in 2019 with 48 farmers from the villages of Nani Chandoori and Dudhkha (Sami block) and Aritha (Harij block).

  PublisherDOI

• Unraveling bofedal change and degradation: Multidimensional analysis of pastoral management, local knowledge, and image analysis in Sajama National Park, Bolivia

  Journal of Mountain Science · 2026-02-01

  article
  PublisherDOI

• Compositional shifts of alpine plant communities across the high Andes

  Global Ecology and Biogeography · 2023 · 37 citations

  • Ecology
  • Environmental science
  • Physical geography

  Abstract Aim Climate change is transforming mountain summit plant communities worldwide, but we know little about such changes in the High Andes. Understanding large‐scale patterns of vegetation changes across the Andes, and the factors driving these changes, is fundamental to predicting the effects of global warming. We assessed trends in vegetation cover, species richness (SR) and community‐level thermal niches (CTN) and tested whether they are explained by summits' climatic conditions and soil temperature trends. Location High Andes. Time period Between 2011/2012 and 2017/2019. Major taxa studied Vascular plants. Methods Using permanent vegetation plots placed on 45 mountain summits and soil temperature loggers situated along a ~6800 km N‐S gradient, we measured species and their relative percentage cover and estimated CTN in two surveys (intervals between 5 and 8 years). We then estimated the annual rate of changes for the three variables and used generalized linear models to assess their relationship with annual precipitation, the minimum air temperatures of each summit and rates of change in the locally recorded soil temperatures. Results Over time, there was an average loss of vegetation cover (mean = −0.26%/yr), and a gain in SR across summits (mean = 0.38 species m 2 /yr), but most summits had significant increases in SR and vegetation cover. Changes in SR were positively related to minimum air temperature and soil temperature rate of change. Most plant communities experienced shifts in their composition by including greater abundances of species with broader thermal niches and higher optima. However, the measured changes in soil temperature did not explain the observed changes in CTN. Main conclusions High Andean vegetation is changing in cover and SR and is shifting towards species with wider thermal niche breadths. The weak relationship with soil temperature trends could have resulted from the short study period that only marginally captures changes in vegetation through time.

  PublisherDOI

• Strategies of diaspore dispersal investment in Compositae: the case of the Andean highlands

  Annals of Botany · 2023-07-25 · 5 citations

  articleOpen access

  BACKGROUND AND AIMS: Understanding diaspore morphology and how much a species invests on dispersal appendages is key for improving our knowledge of dispersal in fragmented habitats. We investigate diaspore morphological traits in high-Andean Compositae and their main abiotic and biotic drivers and test whether they play a role in species distribution patterns across the naturally fragmented high-Andean grasslands. METHODS: We collected diaspore trait data for 125 Compositae species across 47 tropical high-Andean summits, focusing on achene length and pappus-to-achene length ratio, with the latter as a proxy of dispersal investment. We analysed the role of abiotic (temperature, elevation and latitude) and biotic factors (phylogenetic signal and differences between tribes) on diaspore traits and whether they are related to distribution patterns across the Andes, using phylogenomics, distribution modelling and community ecology analyses. KEY RESULTS: Seventy-five percent of the studied species show small achenes (length <3.3 mm) and 67% have high dispersal investment (pappus length at least two times the achene length). Dispersal investment increases with elevation, possibly to compensate for lower air density, and achene length increases towards the equator, where non-seasonal climate prevails. Diaspore traits show significant phylogenetic signal, and higher dispersal investment is observed in Gnaphalieae, Astereae and Senecioneae, which together represent 72% of our species. High-Andean-restricted species found across the tropical Andes have, on average, the pappus four times longer than the achene, a significantly higher dispersal investment than species present only in the northern Andes or only in the central Andes. CONCLUSIONS: Small achenes and high diaspore dispersal investment dominate among high-Andean Compositae, traits typical of mostly three tribes of African origin; but traits are also correlated with the environmental gradients within the high-Andean grasslands. Our results also suggest that diaspore dispersal investment is likely to shape species distribution patterns in naturally fragmented habitats.

  PublisherOA PDFDOI

• Andean peatlands at risk? Spatiotemporal patterns of extreme NDVI anomalies, water extraction and drought severity in a large-scale mining area of Atacama, northern Chile

  International Journal of Applied Earth Observation and Geoinformation · 2022 · 24 citations

  • Physical geography
  • Geography
  • Climatology

  In the Andes, multiple human and climatic factors threaten the conservation of bofedales, a type of high altitude peat forming wetland widely distributed in the tropical and subtropical Andes. In northern Chile, climate change and water extraction for industrial activities are among the most significant threats to these relevant socio-hydrological systems hosting indigenous pastoral communities. In this study, we present an integrated analysis of Normalized Difference Vegetation Index (NDVI) anomalies, drought severity and water rights granted to industry to provide insight on the conservation status of bofedales, historical drivers of their transformation, and current threats. Using Landsat satellite imagery from 1986 to 2018, we identify spatio-temporal NDVI changes of 442 bofedales in one of the leading copper producing regions of the world. The NDVI time series analysis over 32 growing seasons was used to detect extreme anomalies, i.e. values outside the 95 % of the reference frequency distribution, indicating periods of extreme changes in the productivity of these high Andes wetlands. To evaluate the relationship between bofedales NDVI extreme periods to drought and continued water extraction activities, we combine a climate-based multi-temporal-scale drought index (SPEI) with the geospatial latitudinal distribution of water rights granted for extractive industries in the study area. Over the time period of analysis, the total amount of granted water rights increased 465 % from 1,201 l/s recorded before 1985 to 5,584 l/s in 2018. In the areas where the highest amount of water rights are concentrated, i.e. between 21.3°S and 22.1°S, “green” bofedales (NDVI>=0.23) are practically absent. NDVI of the austral summer (JFM) was highly correlated with the severity of drought occurring during the three months of the growing season peak. While our findings show bofedal productivity is mostly influenced by precipitation and temperature of the wet season (JFM) during the study period, results also raise questions regarding possible bofedal loss occurring over the previous 80 years prior to the satellite record, wherein water extraction activities have significantly increased according to official records.

  PublisherDOI

• Understanding Bofedales as Cultural Landscapes in the Central Andes

  Wetlands · 2021-10-27 · 20 citations

  articleOpen access
  PublisherOA PDFDOI

• Using repeat oblique aerial photography and satellite imagery to detect glacial change in the Cordillera Vilcanota, Peru, since 1931

  2021-03-03 · 1 citations

  articleOpen access

  &amp;lt;p&amp;gt;Terrestrial and aerial image analysis has proven to be a valuable survey method for documenting terrestrial landscape change related to, for example, biodiversity, urbanization, and environmental services such as land vegetation or forest cover and use, glacier extent, and water resources. Historical oblique aerial photographs offer exceptional opportunities to extend the observational record beyond the period covered by traditional nadir aerial surveys and satellite imagery. Here we apply these methods in the Cordillera Vilcanota of Southern Peru, home to the largest high alpine lake, Sibinacocha, in the Andes, a primary source of the Amazon River. The Shippee-Johnson aerial expedition of 1931 produced oblique photographs of glaciated peaks of the Cordillera Vilcanota. To determine the extent of glacial loss, we compared the 1931 glacier extents with more recent ones derived from satellite imagery analyses using Agisoft Metashape and Pixcavator. The identification of the flight camera positions from 1931 proved to be challenging, since the original photographs come with only rudimentary information. For three test glaciers, the Metashape analysis showed a glacier recession of between 50% and 95% from 1931 to 2018. Preliminary Pixcavator analysis results demonstrated a area decrease of 62% at two glacier termini between 1931 and 2020. Future studies will include repeating the oblique aerial photographs across the Vilcanota and other Andean mountain ranges, and also include ground truth and UAS imagery analysis.&amp;lt;/p&amp;gt;

  PublisherDOI

• Reframing Pastoral Practices of Bofedal Management to Increase the Resilience of Andean Water Towers

  Mountain Research and Development · 2021 · 31 citations

  1st authorCorresponding
  • Geography
  • Environmental resource management
  • Environmental planning

  Across the Andes, a critical challenge for mountain socioecological systems is securing water for future generations. Pastoral communities are especially vulnerable because their livelihood practices are often unseen or perceived as a threat to natural resource conservation. In addition to the challenges of climate change, socioeconomic and political processes complicate the drivers of pasture degradation and sustainable water management. Often overlooked systems in assessments of Andean water towers are bofedales (high-altitude peat wetlands), which are critical to supporting mountain pastoral livelihoods. While “natural” azonal mountain peatland and humid meadow development occurs across the Andes, we posit that bofedales are sociohydrological systems created through pastoral management practices over generations. Drawing on the results of applied research on bofedales across the Andes and a literature review of published papers, we present a conceptual reframing of bofedal typologies and change analysis, which prioritizes the role of pastoralists in interdisciplinary research and comparative assessments of land-use and land-cover change in Andean highland regions. We identified key socioecological challenges to sustainable bofedal management, related to herder decision-making and articulated within broader socioeconomic processes. Reframing bofedales as sociohydrological constructs permits the identification of actionable knowledge and the support of water conservation practices applied by pastoralists across Andean water tower regions. If Andean pastoralists are recognized as stewards of sociohydrological systems that are critical to water towers, rather than perceived as threats to natural resources, bofedal conservation planning may be prioritized and locally supported.

  PublisherOA PDFDOI

• 6. Satellite Imagery and Community Perceptions of Climate Change Impacts and Landscape Change

  Yale University Press eBooks · 2020-12-31

  book-chapter1st authorCorresponding
  PublisherDOI

• Socio-ecological dimensions of Andean pastoral landscape change: bridging traditional ecological knowledge and satellite image analysis in Sajama National Park, Bolivia

  Regional Environmental Change · 2019-02-21 · 45 citations

  article1st authorCorresponding
  PublisherDOI

Frequent coauthors

• D. A. Slayback

  Goddard Space Flight Center

  12 shared

• Stephan Halloy

  12 shared

• Rosa Isela Meneses

  Academia Nacional de Ciencias de Bolivia

  12 shared

• Harald Pauli

  University of Vienna

  10 shared

• Francisco Cuesta

  Universidad de Las Américas

  8 shared

• Julieta Carilla

  National University of Tucumán

  8 shared

• Luis D. Llambí

  7 shared

• Kelly A. Hopping

  Boise State University

  6 shared

Awards & honors

• GLORIA (Global Observation and Research Initiative in Alpine…