Vania Stefanova

University of Minnesota

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Blas L. Valero‐Garcés

Instituto Pirenaico de Ecología

Ana Moreno

Instituto Pirenaico de Ecología

Juan Pablo Corella

Instituto de Química Física Blas Cabrera

Penélope González‐Sampériz

Instituto Pirenaico de Ecología

Bryan N. Shuman

University of Wyoming

Mario Morellón

Universidad Complutense de Madrid

Juan José González Trueba

Universidad de Cantabria

Ulf Büntgen

Czech Academy of Sciences, Global Change Research Institute

Herbert E. Wright

University of Minnesota

Sergi Pla‐Rabès

Centre for Research on Ecology and Forestry Applications

Cooperative Institutions

Consejo Superior de Investigaciones Científicas

Instituto Pirenaico de Ecología

National Research Council

Bulgarian Academy of Sciences

University of Bern

Universidad Complutense de Madrid

University of Minnesota

Oeschger Centre for Climate Change Research

Universidad de Zaragoza

Universitat de Barcelona

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Interacting effects of fire and hydroclimate on oak and beech community prevalence in the southern Great Lakes region

Journal of Ecology (2024)

Nora Schlenker Jonathan Johnson Tessa Ray‐Cozzens Vania Stefanova David M. Nelson

Abstract Rising temperatures, increasing hydroclimate variability and intensifying disturbance regimes increase the risk of rapid ecosystem conversions. We can leverage multi‐proxy records of past ecosystem transformations to understand their causes and ecosystem vulnerability to rapid change. Prior to Euro‐American settlement, northern Indiana was a mosaic of prairie, oak‐dominated forests/woodlands and beech‐dominated hardwood forests. This heterogeneity, combined with well‐documented but poorly understood past beech population declines, make this region ideal for studying the drivers of ecosystem transformations. Here, we present a new record from Story Lake, IN, with proxies for vegetation composition (pollen), fire (charcoal) and beech intrinsic water use efficiency (δ 13 C of beech pollen; δ 13 C beech ). Multiple proxies from the same core enable clear establishment of lead–lag relationships. Additionally, δ 13 C beech enables direct comparisons between beech population abundance and physiological responses to changing environments. We compare Story Lake to a nearby lake‐level reconstruction and to pollen records from nearby Pretty and Appleman Lakes and the distal Spicer Lake, to test hypotheses about synchrony and the spatial scale of governing processes. The 11.7 ka sediment record from Story Lake indicates multiple conversions between beech‐hardwood forest and oak forest/woodland. Beech pollen abundances rapidly increased between 7.5 and 7.1 ka, while oak declined. Oak abundances increased after 4.6 ka and remained high until 2.8 ka, indicating replacement of mesic forests by oak forest/woodland. At 2.8 ka, beech abundances rapidly increased, indicating mesic forest reestablishment. Beech and oak abundances correlate with charcoal accumulation rates but beech abundance is not correlated with δ 13 C beech . Fluctuations in beech abundances are synchronous among Story, Appleman and Pretty Lakes, but asynchronous between Story and Spicer Lakes, suggesting regulation by local‐scale vegetation‐fire‐climate feedbacks and secondarily by regional‐scale drivers. Holocene forest composition and fire dynamics appear to be closely co‐regulated and may be affected by local to regional climate variations. The importance of extrinsic drivers and positive/negative feedbacks changes over time, with higher ecoclimate sensitivity before 2.8 ka and greater resilience afterwards. Synthesis : Overall, oak‐ and beech‐dominated ecosystems were highly dynamic over the Holocene, with multiple ecosystem conversions driven by shifting interactions among vegetation, hydroclimate and fire regime.

Temperate deciduous forest

10.1111/1365-2745.14289

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Citations (1)

SOIL EROSION RISK ASSESSMENTS USING GIS TECHNOLOGIES BULGARIAN EXPERIENCE

Bulgarian Journal of Agricultural Science (2016)

Svetla Rousseva I. Malinov Vania Stefanova

Bulgarian

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A 2500-year multi-proxy reconstruction of climate change and human activities in northern Spain: The Lake Arreo record

Palaeogeography Palaeoclimatology Palaeoecology (2013)

Juan Pablo Corella Vania Stefanova Adel El Anjoumi Eugenio Rico Santiago Giralt

Radiometric dating

Paleoclimatology

Ice core

10.1016/j.palaeo.2013.06.022

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Citations (89)

Elevational gradients during the Late-Glacial/Holocene vegetational transition in southern Bulgaria

Vegetation History and Archaeobotany (2006)

Vania Stefanova Maria Lazarova Herbert E. Wright

Macrofossil

Steppe

Mire

10.1007/s00334-006-0049-7

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Citations (12)

406 Southern Pyrenees Climate of the Past

Mario Morellón Ana Pérez Sanz Juan Pablo Corella Ulf Büntgen Jordi Catalán

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Interpreting Resilience through Long-Term Ecology: Potential Insights in Western Mediterranean Landscapes

Graciela Gil‐Romera Lourdes López Merino José S. Carrión Penélope González‐Sampériz Celia Martín‐Puertas

Many studies on ecosystem resilience often lack sufficiently long time scales to determine potential cycles of landscape response. In this paper we review some examples on how palaeoecology has provided an important aid to modern ecology in understanding ecosystem resilience. We focus some of these ideas on two Holocene sites from Southern Spain (Zonar and Gador) where current plant diversity is very high. Both sites presented resilient pattern at centennial and millennial time scales with several stable phases. Vegetation in Zonar proved to be very sensitive to environmental changes, especially moisture availability while forest in Gador responded elastically to fire and drought to a threshold level when the forest recede to a more open landscape. We conclude that any serious attempt to understand ecosystem resilience should include the long-term perspective.

Historical Ecology

Paleoecology

Resilience

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Citations (23)

Late Holocene vegetation changes in the Northern Pirin Mountains (southwestern Bulgaria). Palynological data from Lake Suho Breznishko and Lake Okadensko

Geologica Carpathica (2005)

Juliana Atanassova Vania Stefanova

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A 1400-years flood frequency reconstruction for the Basque country (N Spain): Integrating geological, historical and instrumental datasets

Quaternary Science Reviews (2021)

Juan Pablo Corella Gerardo Benito Agustín Monteoliva Javier Sigró Mikel Calle

We present the first reconstruction of past flood events variability in the Basque Country and Western Ebro Basin (Northern Spain) integrating instrumental hydrological datasets (last 20 years), documentary archives (last 700 years) and Lake Arreo (655 m a.s.l.) sedimentary paleoflood record (last 1400 years). In this lake, allochthonous coarse and fine detrital layers (CDL and FDL respectively) intercalated within endogenic laminites were identified and interpreted as high- and moderate-energy flood events. The interplay between human activities and hydroclimate variability has controlled the deposition of these flood layers. Gauged data for the last 20 years suggest that floods are typically generated by heavy rainfall events on saturated soils after several days of continuous rainfall. These events occur mostly during the cold season (Oct–May). The reconstructed frequency of high-magnitude flood events from the lake record is coherent with the historical cold-season floods from Basque rivers. The lowest flood frequency took place during the 6–7th and 10–15th centuries, while higher flood frequency occurred during the 8–9th centuries and the last 500 years. Fluvial and lacustrine paleoflood records and documentary evidence show abrupt and large increases in extreme flood frequency during the termination of the Little Ice Age (1830–1870 CE) and mid to late 20th century, both periods of Rapid Climate Change (RCC). The significant increase in flood frequency observed during RCC suggests that a similar pattern could be expected in the near future with the ongoing global warming.

10.1016/j.quascirev.2021.106963

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Citations (12)

Weak precipitation δ2H response to large Holocene hydroclimate changes in eastern North America

Quaternary Science Reviews (2023)

Ioana C. Stefanescu Bryan N. Shuman Laurie D. Grigg Adriana Bailey Vania Stefanova

Deglaciation

Paleoclimatology

Holocene climatic optimum

10.1016/j.quascirev.2023.107990

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Citations (4)

Landscape heterogeneity and response of lake ecosystems to changes in climate and peatland expansion over the past 7500 years at the tundra-forest border of northern Manitoba, Canada

The Holocene (2024)

Charles E. Umbanhowar Philip Camill Mark B. Edlund Will O. Hobbs C. E. Geiss

Responses of Arctic lakes to climate change are complex and heterogeneous at regional to local scales, but there are few studies comparing multiple sites within the same landscape. We studied sediment cores recovered from seven lake sites located within the forest-tundra biome of northern Manitoba, Canada. We first used sediment core pollen from the seven sites to reconstruct July temperatures and total annual precipitation for the past 7500 years based on the modern analog technique. Lake responses and peatland expansion were analyzed based on changes in the concentration and quality of organic matter, biogenic silica (bSi), Sphagnum spores, and published peat core basal dates. Changes in sediment organic matter and bSi were concentrated prior to 4500 cal. Yr BP. From 7500 to 3100 cal. Yr BP, July temperatures rose by ~3°C, and total annual precipitation fell by 200 mm; there was little change in temperature or precipitation after 3100 cal. Yr BP. Sphagnum spore concentrations exceeded 0.5% at all of the sites at 7500 cal. Yr BP indicating the early presence of peatlands. Spores increased markedly after 4500 cal. Yr BP in agreement with timing of peat basal dates, but the magnitude and timing of changes varied widely among sites likely reflecting local differences in hydrology or topography. The use of hierarchical generalized additive models provided a unified regional pattern of Holocene climate for northern Manitoba, even though lake responses to climate and peatland expansion differed greatly.

10.1177/09596836241254479

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Citations (0)