1. Age-dependent moisture response of conifers near their cold range limitJan Tumajer, Grudd Håkan, Jernej Jevšenak, Andreas J. Kirchhefer, Francesco Marotta, Jiří Mašek, Kiara Maria Nowatzki, Nikolaus Obojes, Markus Stoffel, Václav Treml, Jelena Lange, 2025, original scientific article Abstract: Growth dynamics of cold subarctic and subalpine forests are primarily sensitive to temperature, but growth responses may vary across regions or shift over tree ontogeny. Systematic assessments of spatial, interspecific, and demographic variation in temperature and moisture limitation of tree growth at cold distribution margins are essential for enhancing our understanding of how these ecosystems will evolve under climate regimes. To address this gap, we built a network of 22 tree-ring width chronologies from cold forests covering two regions (Fennoscandia, European Alps), three species (Pinus sylvestris, Pinus cembra, Larix decidua), and two age cohorts (45–100 and >150 years). We combined daily climate-growth correlations with the process-based Vaganov-Shashkin growth model to identify differences in critical growth factors between species and age cohorts. In addition, we assessed the coincidence of unusually wide and narrow tree rings with years of specific climatic anomalies. Although growing season temperature was the dominant growth-limiting factor, seasonal effects of water balance on tree growth were considerably large and varied systematically between regions, species, and particularly age cohorts. The growth of young P. sylvestris in Fennoscandia responded negatively to water balance and narrow rings coincided with wet years. In contrast, the growth of young P. cembra in the Alps was drought-limited. Old trees of all species and both age cohorts of L. decidua in the Alps showed limited sensitivity to water balance. The patterns of climate-growth responses in cohort chronologies based on tree age at the year of coring were similar to ontogenetic shifts of climate-growth responses if chronologies were based on the cambial age of individual rings. Our results stress the need to account for interspecific and demographic differences in sensitivity to climate in large-scale studies of cold forest ecosystems.
Keywords: boreal forest, Larix, subalpine forest, pinus, tree ring, Vaganov-Shashkin model
Published in DiRROS: 04.06.2025; Views: 684; Downloads: 349
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2. Phosphorus limitation promotes soil carbon storage in a boreal forest exposed to long-term nitrogen fertilizationEtienne Richy, Tania Fort, Inaki Odriozola, Petr Kohout, Florian Barbi, Tijana Martinović, Boris Tupek, Bartosz Adamczyk, Aleksi Lehtonen, Raisa Mäkipää, Petr Baldrian, 2024, original scientific article Abstract: Forests play a crucial role in global carbon cycling by absorbing and storing significant amounts of atmospheric carbon dioxide. Although boreal forests contribute to approximately 45% of the total forest carbon sink, tree growth and soil carbon sequestration are constrained by nutrient availability. Here, we examine if long-term nutrient input enhances tree productivity and whether this leads to carbon storage or whether stimulated microbial decomposition of organic matter limits soil carbon accumulation. Over six decades, nitrogen, phosphorus, and calcium were supplied to a Pinus sylvestris-dominated boreal forest. We found that nitrogen fertilization alone or together with calcium and/or phosphorus increased tree biomass production by 50% and soil carbon sequestration by 65% compared to unfertilized plots. However, the nonlinear relationship observed between tree productivity and soil carbon stock across treatments suggests microbial regulation. When phosphorus was co-applied with nitrogen, it acidified the soil, increased fungal biomass, altered microbial community composition, and enhanced biopolymer degradation capabilities. While no evidence of competition between ectomycorrhizal and saprotrophic fungi has been observed, key functional groups with the potential to reduce carbon stocks were identified. In contrast, when nitrogen was added without phosphorus, it increased soil carbon sequestration because microbial activity was likely limited by phosphorus availability. In conclusion, the addition of nitrogen to boreal forests may contribute to global warming mitigation, but this effect is context dependent.
Keywords: carbon storage, microbial communities, boreal forest, fertilization
Published in DiRROS: 23.12.2024; Views: 843; Downloads: 461
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