Papers by Anastasia Knorre
Decoupled leaf-wood phenology in two pine species from contrasting climates: Longer growing seasons do not mean more radial growth
Agricultural and Forest Meteorology
Tree-Ring Research, 2016
The biogeochemistry and ecology of the Arctic environment have been heavily impacted by anthropog... more The biogeochemistry and ecology of the Arctic environment have been heavily impacted by anthropogenic pollution and climate change. We examined long-term changes in wood chemistry of the dominant tree species of Siberian forests with inductively coupled plasma mass spectrometry analysis to study interaction between climate change and environmental trace elements. Variance and correspondence of 26 element concentrations of larch tree rings from the Taymyr Peninsula were statistically analyzed from AD 1300 to 2000. Unexpectedly, the tree rings reveal pronounced depletion of xylem Ca and Mg concentrations and enrichment of P, K, Mn, Rb, Sr and Ba concentrations after ca. 1950. The significant trends are unprecedented for the last 700 years, but the environmental mechanism triggering the change is not obvious. We hypothesize that the declining xylem calcium and manganese is a response to soil acidification from to air pollution as seen in experimental acidification elsewhere. The increase of P, K, and Mn concentrations, however, seems more likely a result of changes in root efficiency and excess water-soluble minerals liberated by the permafrost thaw and warming temperatures. Changes in wood chemistry altered by soil nutrient availability may signal mounting stress on arctic vegetation.
Stable isotopes (delta13C and delta18O) in Larix Sibirica tree rings under dry conditions in the forest-steppe in Siberia during the last 150 years
Tree ring width, density and ratio of stable isotopes (13C/12C and 18O/16O) in wood and cellulose... more Tree ring width, density and ratio of stable isotopes (13C/12C and 18O/16O) in wood and cellulose were determined for larch (Larix sibirica Ledeb.) growing under water deficit conditions in the forest-steppe zone in Central Siberia. Dendroclimatic analysis of the chronologies indicated precipitation to be the most important factor determining tree-ring structure. Precipitation of June is significantly correlated with tree ring
Isotope variability in larch tree rings of Siberia: climate and ecology
Paleoclimate reconstructions from tree-ring widths and maximum wood density are most successful i... more Paleoclimate reconstructions from tree-ring widths and maximum wood density are most successful in localities with extreme climates for particular tree species that are most responsive. Climate proxy records from other, less conventional, tree-ring parameters have been rapidly increasing over the last decade. We assembled a unique dataset of carbon and oxygen isotope ratios of larch tree rings from the northern and southern tree-lines of Siberia, variously sub-sampled and analyzed (whole wood and cellulose & annual and 5-year sequences from individual trees and pooled). Larch samples from the north in Taymyr (Larix gmelinii Rupr.) published by Sidorova et al. (2010) and from the south collected in Khakasia (Larix sibirica Ledeb.) both came from highly temperate continental climates exhibiting similar amounts of precipitation and observed temperature trends. However, the sites differ because temperature is the dominant factor limiting radial tree growth in the north, whereas precipit...
Eurasian Soil Science, 2013
The microbial activity of peat soils was studied in boggy larch forests and in an oligo mesotroph... more The microbial activity of peat soils was studied in boggy larch forests and in an oligo mesotrophic bog in the basins of the Kochechum and Nizhnaya Tunguska rivers (central Evenkia). It was found that the organic matter transformation in the peat soils of all the plots is mainly performed by oligotrophic bacteria composing 88-98% of the total bacterial complex. The major contribution to the organic matter destruction belonged to the heterotrophic microorganisms, the activity of which depended on the permafrost depth and the soil temperature, the soil acidity, and the botanical composition of the peat. Peat soils were characterized by different activities as judged from their microbiological and biochemical parameters. The functioning of microbial communities in the studied ecotopes of the permafrost zone was within the range of natural varia tions, which pointed to their ecological stability.
Here, we present the results of an on-going study of tree-ring growth of conifers in Russia’s con... more Here, we present the results of an on-going study of tree-ring growth of conifers in Russia’s continuous permafrost zone in northern Siberia, from 61-72°N and 90-148°E. Tree-ring data from a variety of habitats between 20 and 600 m asl with different climate and thermo-hydrological regimes of soils are analyzed. While in some cases up to 60-70% of the year-to-year tree-ring width and maximum latewood density variability can be explained by summer temperature variations alone, we find that the seasonal dynamics of permafrost also plays an important role in defining the overall rate of radial tree growth. Wider rings are generally formed on sites with a deeper active soil layer, which itself depends on the geographical location of a site, as well as its ground vegetation, stand parameters and fire history. Waterlogged permafrost may further act as a source of water for trees under exceptionally dry summer seasons.
Instituto Pirenaico de Ecología (IPE-CSIC), Avda. Montañana 1005, E-50059 Zaragoza, Spain Forest ... more Instituto Pirenaico de Ecología (IPE-CSIC), Avda. Montañana 1005, E-50059 Zaragoza, Spain Forest Ecology and Restoration Group, Department of Life Sciences, University of Alcalá, E-28802 Alcalá de Henares (Madrid), Spain Sukachev Institute of Forest SB RAS, Akademgorodok 50/28, 660036 Krasnoyarsk, Russia Institute of Ecology and Geography, Siberian Federal University, pr. Svobodny 82, 660041, Krasnoyarsk, Russia Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, 08028 Barcelona, Spain Department of Forestry, Siberian Federal University, 660041 Krasnoyarsk, Russia Institute of Plant and Animal Ecology SD RAS, 8 Marta Str. 202, Yekaterinburg, 620144, Russia Department of Crop and Forest Sciences-AGROTECNIO Center, Universitat de Lleida, Rovira Roure 191, E 25198 Lleida, Spain
Tree growth and forest ecosystem functioning in Eurasia under extreme climate conditions
ABSTRACT The main goal of this study is to improve our understanding of the influence of a changi... more ABSTRACT The main goal of this study is to improve our understanding of the influence of a changing climate on trees in extreme conditions by a detailed analysis of the factors controlling tree-ring growth. We investigated forest ecosystems in regions that are very sensitive to climatic changes and where rapid and dramatic environmental and climatic changes are on-going, namely, the high latitude permafrost region in Central Siberia (Russia), the semi-arid dry areas in Central Asia (Uzbekistan) and high-altitude sites in the Alps (Switzerland). Tree-ring parameters studied were ring-width, density, cell number and structure and the ratio of carbon and oxygen isotopes. An important aspect of the work was the characterization of seasonal growth and water supply of trees. Intra-seasonal dynamics of tree-ring formation was correlated with monitored environmental factors, such as air and soil temperature and moisture, permafrost depth and the isotope composition of soil water, of precipitation, and of stream water. Intra-annual and long-term variability of the main tree-ring parameters were compared for the different regions. The results obtained help us to understand better tree-physiological processes valid under contrasting environmental conditions. For instance, the relationship between the onset of cell division in the cambium and the thermo-hydrological soil regime was used to determine the period of the year with the highest influence on the start of tree-ring formation. Seasonally resolved oxygen isotope depth profiles of soil water and concurrent xylem and leaf water measurements show the importance of time-lags between precipitation, leaf processes and growth. The data obtained are important for improving tree-ring growth models and estimating future tree growth under climate change. Funding: SNF SCOPES IZ73Z0_128035
Климатически обусловленная динамикарадиального прироста кедра и пихтыв горно-таежном поясе природного парка «Ергаки»
Stem growth and stem sap flow measurements of three conifer tree species in Siberia
IOP Conference Series: Earth and Environmental Science
This work is targeted to evaluate the reaction of individual trees against periodic and punctual ... more This work is targeted to evaluate the reaction of individual trees against periodic and punctual environmental stressing events with a network of long-term monitoring of tree water/growth-related processes in various geographic and climatic areas. Instrumental measurements of stem circumferential/radial size changes (dRc/dR) using band/point dendrometers and stem sap flow rates (Q) using a trunk segment heat balance method in Scots pine, Siberian larch, and Dahurian larch trees have been carried out at three research sites in Krasnoyarsk Krai, Russia. Analysis of perennial dRc/dR and seasonal Q data obtained in 2015-2019 allows us to characterize the seasonality and features of the tree stem growth and stem water transport rates specific for each of the studied conifer species and on different temporal scales (diurnal, inter/intra-seasonal, and annual). The archived in-situ data are used to verify the efficiency of some process-based BS-and stochastic VS-tree growth and phenology mo...
Estimating the rate of permafrost elevation under larches in Central Ėvenkiya using dendrochronological methods
Методология получения 600-летней многоэлементной летописи на основе годичных колец лиственницы с полуострова Таймыр, Россия
Trees
In conifers tracheids fulfill most of the main wood functions (mechanical support, water transpor... more In conifers tracheids fulfill most of the main wood functions (mechanical support, water transport). Earlywood tracheids account for most hydraulic conductivity within the annual tree ring. Therefore, dry conditions during the early growing season, when earlywood is formed, should lead to the formation of narrow tracheid lumens and a dense earlywood. Here we test if there is an inverse relationship between minimum wood density and early growing-season (spring) precipitation. We study growth and density data of three Pinaceae species (Pinus sylvestris, Pinus nigra, and Larix sibirica) widely distributed in three cool-dry Eurasian regions from the forest-steppe (Russia, Mongolia) and Mediterranean (Spain) biomes. Using dendrochronology, we measured for each annual tree ring and the common 1950-2002 period the following variables: earlywood (EW hereafter) and latewood widths (LW hereafter), and minimum (MN hereafter) and maximum wood density (MX hereafter). As expected, dry early-growing season (spring) conditions were associated to low EW values but, most importantly, to high MN values in the three study species. The associations between MN and spring precipitation were stronger than those observed with EW. We interpret the relationship between spring water availability and high minimum density as a drought-induced reduction in lumen diameter, hydraulic conductivity and growth. Consequently, forecasted growing-season drier conditions would translate into increased minimum wood density and reflect a reduction in hydraulic conductivity, radial growth and wood formation. Increased aridity would diminish the ability of Eurasian conifer forests subjected to coldness and drought to fix and store carbon as durable woody pools.
Functional Ecology, 2017
Weaker growth-climate relationships as elevation increased highlighted the major role of the alti... more Weaker growth-climate relationships as elevation increased highlighted the major role of the altitude-dependent thermal gradient in growth responsiveness to drought; however, an intensified ∆ 13 C i response to spring water availability across elevation belts observed from mid-1970s onwards suggested regional shifts in tree physiological activity linked to earlier seasonal drought impacts. Warming-induced drought stress is spreading to higher altitudes in Iberian pinewoods as multispecies growth is linked to progressively tighter stomatal control of water losses reflected in wood ∆ 13 C.
Phenological shifts compensate warming-induced drought stress in southern Siberian Scots pines
European Journal of Forest Research
Phenological shifts of abiotic events, producers and consumers across a continent
Nature Climate Change
Ecological and conceptual consequences of Arctic pollution
Ecology Letters
Differences in spatial versus temporal reaction norms for spring and autumn phenological events
Proceedings of the National Academy of Sciences
For species to stay temporally tuned to their environment, they use cues such as the accumulation... more For species to stay temporally tuned to their environment, they use cues such as the accumulation of degree-days. The relationships between the timing of a phenological event in a population and its environmental cue can be described by a population-level reaction norm. Variation in reaction norms along environmental gradients may either intensify the environmental effects on timing (cogradient variation) or attenuate the effects (countergradient variation). To resolve spatial and seasonal variation in species’ response, we use a unique dataset of 91 taxa and 178 phenological events observed across a network of 472 monitoring sites, spread across the nations of the former Soviet Union. We show that compared to local rates of advancement of phenological events with the advancement of temperature-related cues (i.e., variation within site over years), spatial variation in reaction norms tend to accentuate responses in spring (cogradient variation) and attenuate them in autumn (counterg...
Environmental Research Letters
Wildfires are an important factor in controlling forest ecosystem dynamics across the circumpolar... more Wildfires are an important factor in controlling forest ecosystem dynamics across the circumpolar boreal zone. An improved understanding of their direct and indirect, short-to long-term impacts on vegetation cover and permafrost-vegetation coupling is particularly important to predict changes in carbon, nutrient and water cycles under projected climate warming. Here, we apply dendrochronological techniques on a multi-parameter dataset to reconstruct the effect of wildfires on tree growth and seasonal permafrost thaw depth in Central Siberia. Based on annually-resolved and absolutely dated information from 19 Gmelin larch (Larix gmelinii (Rupr.) Rupr.) trees and active soil layer thickness measurements, we find substantial stand-level die-off, as well as the removal of ground vegetation and the organic layer following a major wildfire in 1896. Reduced stem growth coincides with increased δ 13 C in the cellulose of the surviving trees during the first decade after the wildfire, when stomatal conductance was reduced. The next six to seven decades are characterized by increased permafrost active soil layer thickness. During this period of post-wildfire ecosystem recovery, enhanced tree growth together with positive δ 13 C and negative δ 18 O trends are indicative of higher rates of photosynthesis and improved water supply. Afterwards, a thinner active soil layer leads to reduced growth because tree physiological processes become limited by summer temperature and water availability. Revealing long-term effects of forest fires on active soil layer thickness, ground vegetation composition and tree growth, this study demonstrates the importance of complex vegetation-permafrost interactions that modify the trajectory of post-fire forest recovery across much of the circumpolar boreal zone. To further quantify the influence of boreal wildfires on large-scale carbon cycle dynamics, future work should consider a wide range of tree species from different habitats in the high-northern latitudes.
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Papers by Anastasia Knorre