Jelena Lange

The stability of global forest ecosystems is challenged by the accelerated pace of climate change, raising questions about their role as future carbon reservoirs. Intensifying drought events affect forest productivity and dieback at regional scales, yet how drought sensitivity and resilience components vary across the full distribution of widespread tree species remains insufficiently quantified. Here, we compile a pan-Eurasian network of 534 Pinus sylvestris tree-ring chronologies spanning the species’ full ecological range and quantify growth departures and resilience components during the most extreme summer droughts of the past century. Drought impacts diverge systematically along major climatic gradients. Growth reductions exceed 70% in cold-dry and warm semi-humid regions, while cool–humid forests show muted and even positive departures. Resistance is lowest under prolonged droughts in continental cold–dry interiors and under short summer droughts in semi-humid lowlands, while recovery capacity is highest where growth losses are most severe, reflecting local adaptations in drier regions. Despite coherent biome-scale patterns, substantial site-level variability indicates that growth legacies often persist beyond the event year. Nonlinear models show that resilience-climate relationships are shaped not only by mean climate conditions, but also by atmospheric water demand, site-level water balance, and thermal stability across climatic domains. Together, these results provide a range-wide assessment of drought impacts, demonstrating how prevailing climate conditions modulates forest stability and carbon sequestration capacity under intensifying climate extremes.

Warming shifts isotherms upwards and previously cold-limited stands can reveal signs of moisture-limited growth. However, the pace of this transition and its characteristics are unclear. To bridge this gap, we present outputs of an intense monitoring effort of tree growth and phenology from a Picea abies stand located originally at the treeline in the Krkonoše Mts. at the Czech-Polish border. This site has been gradually lagging behind the advancing treeline isotherm. During a 12-year period between 2014 and 2025, we collected xylogenesis data, measured stem expansion and shrinkage using dendrometers, and monitored microclimate and leaf phenology. For each year, we derived critical growth dates (start, end, peak growth date), and mean and maximum growth rates for both xylogenesis and dendrometer data. In addition, we evaluated the time series of the tree water deficit. Our results show that despite high inter-annual variability, there was a trend towards a longer duration of xylogenesis, mainly associated with the extension of the cell wall thickening phase. Secondly, we found a reduction in the mean daily rate of cell formation. These trends observed at the cellular level were consistent with observations from dendrometers. The period of growth extended towards the end of the summer and the mean growth rates slightly decreased over time. Interestingly, tree water deficit increased over time with more frequent summer periods with negative climatic water balance and strongly negative soil water potentials. This was reflected in stem growth mainly in the driest years (2018, 2019, 2024) when growth cessation was the earliest within the entire period of monitoring. Our intense growth monitoring witnesses a transition from a strictly cold-limited treeline stand towards tree growth with occasional signs of moisture limitation. Although tree growth was unambiguously affected by drought only during the warmest and driest years, mean growth rates have been slightly declining due to increasing latent tree water deficits.

Treeline ecotones in complex mountain landscapes are exposed to pronounced differences in irradiation and soil nutrient availability. Different amounts of nutrients and direct solar energy can influence tree stem growth, especially in lower parts of a treeline ecotone, where trees are still temperature limited, though located below the upper margin of tree life. We hypothesized that, at two sites located on north- and south-facing slopes, differences in nutrient availability outperform temperature differences in modulating stem growth rates, while growth phenology is driven by temperature seasonality. To test this hypothesis, we compared the growth phenology and kinetics of Picea abies in the lower part of a treeline ecotone between a north-facing slope with relatively nutrient-rich soils and a south-facing slope with nutrient-poor soils. We analysed intra-annual wood formation, soil and air microclimate, and soil and needle nutrient contents. Our results showed that thermal differences between south- and north-facing slopes are small but nontrivial, involving higher daytime temperature at the south-facing slope and longer irradiation at the north-facing slope during the middle part of the growing season. The timings of growth onset and maximum growth rate were almost synchronized between both slopes. Accordingly, annual stem growth at both sites was most sensitive to the meteorological conditions at the start of the growing season and around the summer solstice. However, the absolute growth rate was higher on the north-facing slope, consistent with a higher availability and content of base cations in the soil and needles. Our results suggest that temperature governs growth phenology at the lower part of the treeline ecotone, but nutrient availability modulates the growth rate in the peak season when temperature no longer limits cambial activity. We demonstrated that the effect of nutrient availability can be superior to the effect of slope aspect for stem growth rates of Picea abies located in the lower part of a treeline ecotone in a temperate mountain range.

Treeline ecotones in complex mountain landscapes are exposed to pronounced differences in irradiation and soil nutrient availability. Different amounts of nutrients and direct solar energy can influence tree stem growth resulting in variation of growth rates and growth phenology across lower parts of treeline ecotone. We hypothesized that at two contrasting sites located on north and south-facing slopes, differences in nutrient availability outperform temperature differences in modulating stem growth rates while growth phenology is driven by the course of seasonal temperature. To test this hypothesis, we compared the growth phenology and kinetics of Picea abies in the lower part of treeline ecotone between a north-facing slope with relatively nutrient-rich soils and a south-facing slope with nutrient-poor soils. We analysed intra-annual wood formation and its response to ambient climate, as well as soil and air microclimate and soil and needle nutrient content. Our results showed that thermal differences in treeline ecotones between south and north-facing slopes in temperate mountains are small but nontrivial involving higher daytime temperatures at south-facing slopes and longer irradiation of north-facing slopes during the middle part of growing season. The timing of growth onset and maximum growth rate were almost identical on both slopes. Accordingly, annual stem growth at both sites was most sensitive to the meteorological conditions at the start of the growing season and around the summer solstice. However, the absolute growth rate was higher on the north-facing slope, consistent with a higher availability and content of base cations in the soil and the needles. Our results suggest that temperature governs growth phenology at the lower part of the treeline ecotone, but nutrient availability modulates the growth rate in the peak season when temperature no longer limits cambial activity. We conclude that the effect of nutrient availability can be superior to the effect of slope aspect for stem growth rates of Picea abies located in the lower part of treeline ecotone in temperate mountain range.

Treeline ecotones in complex mountain landscapes are exposed to pronounced differences in irradiation and soil nutrient availability. Different amounts of nutrients and direct solar energy can influence tree stem growth resulting in variation of growth rates and growth phenology across lower parts of treeline ecotone. We hypothesized that at two contrasting sites located on north and south-facing slopes, differences in nutrient availability outperform temperature differences in modulating stem growth rates while growth phenology is driven by the course of seasonal temperature. To test this hypothesis, we compared the growth phenology and kinetics of Picea abies in the lower part of treeline ecotone between a north-facing slope with relatively nutrient-rich soils and a south-facing slope with nutrient-poor soils. We analysed intra-annual wood formation and its response to ambient climate, as well as soil and air microclimate and soil and needle nutrient content. Our results showed that thermal differences in treeline ecotones between south and north-facing slopes in temperate mountains are small but nontrivial involving higher daytime temperatures at south-facing slopes and longer irradiation of north-facing slopes during the middle part of growing season. The timing of growth onset and maximum growth rate were almost identical on both slopes. Accordingly, annual stem growth at both sites was most sensitive to the meteorological conditions at the start of the growing season and around the summer solstice. However, the absolute growth rate was higher on the north-facing slope, consistent with a higher availability and content of base cations in the soil and the needles. Our results suggest that temperature governs growth phenology at the lower part of the treeline ecotone, but nutrient availability modulates the growth rate in the peak season when temperature no longer limits cambial activity. We conclude that the effect of nutrient availability can be superior to the effect of slope aspect for stem growth rates of Picea abies located in the lower part of treeline ecotone in temperate mountain range.

Treeline ecotones in complex mountain landscapes are exposed to pronounced differences in irradiation and soil nutrient availability. Different amounts of nutrients and direct solar energy can influence tree stem growth resulting in variation of growth rates and growth phenology across lower parts of treeline ecotone. We hypothesized that at two contrasting sites located on north and south-facing slopes, differences in nutrient availability outperform temperature differences in modulating stem growth rates while growth phenology is driven by the course of seasonal temperature. To test this hypothesis, we compared the growth phenology and kinetics of Picea abies in the lower part of treeline ecotone between a north-facing slope with relatively nutrient-rich soils and a south-facing slope with nutrient-poor soils. We analysed intra-annual wood formation and its response to ambient climate, as well as soil and air microclimate and soil and needle nutrient content. Our results showed that thermal differences in treeline ecotones between south and north-facing slopes in temperate mountains are small but nontrivial involving higher daytime temperatures at south-facing slopes and longer irradiation of north-facing slopes during the middle part of growing season. The timing of growth onset and maximum growth rate were almost identical on both slopes. Accordingly, annual stem growth at both sites was most sensitive to the meteorological conditions at the start of the growing season and around the summer solstice. However, the absolute growth rate was higher on the north-facing slope, consistent with a higher availability and content of base cations in the soil and the needles. Our results suggest that temperature governs growth phenology at the lower part of the treeline ecotone, but nutrient availability modulates the growth rate in the peak season when temperature no longer limits cambial activity. We conclude that the effect of nutrient availability can be superior to the effect of slope aspect for stem growth rates of Picea abies located in the lower part of treeline ecotone in temperate mountain range.

Treeline ecotones in complex mountain landscapes are exposed to pronounced differences in irradiation and soil nutrient availability. Different amounts of nutrients and direct solar energy can influence tree stem growth resulting in variation of growth rates and growth phenology across lower parts of treeline ecotone. We hypothesized that at two contrasting sites located on north and south-facing slopes, differences in nutrient availability outperform temperature differences in modulating stem growth rates while growth phenology is driven by the course of seasonal temperature. To test this hypothesis, we compared the growth phenology and kinetics of Picea abies in the lower part of treeline ecotone between a north-facing slope with relatively nutrient-rich soils and a south-facing slope with nutrient-poor soils. We analysed intra-annual wood formation and its response to ambient climate, as well as soil and air microclimate and soil and needle nutrient content. Our results showed that thermal differences in treeline ecotones between south and north-facing slopes in temperate mountains are small but nontrivial involving higher daytime temperatures at south-facing slopes and longer irradiation of north-facing slopes during the middle part of growing season. The timing of growth onset and maximum growth rate were almost identical on both slopes. Accordingly, annual stem growth at both sites was most sensitive to the meteorological conditions at the start of the growing season and around the summer solstice. However, the absolute growth rate was higher on the north-facing slope, consistent with a higher availability and content of base cations in the soil and the needles. Our results suggest that temperature governs growth phenology at the lower part of the treeline ecotone, but nutrient availability modulates the growth rate in the peak season when temperature no longer limits cambial activity. We conclude that the effect of nutrient availability can be superior to the effect of slope aspect for stem growth rates of Picea abies located in the lower part of treeline ecotone in temperate mountain range.

Treeline ecotones in complex mountain landscapes are exposed to pronounced differences in irradiation and soil nutrient availability. Different amounts of nutrients and direct solar energy can influence tree stem growth resulting in variation of growth rates and growth phenology across lower parts of treeline ecotone. We hypothesized that at two contrasting sites located on north and south-facing slopes, differences in nutrient availability outperform temperature differences in modulating stem growth rates while growth phenology is driven by the course of seasonal temperature. To test this hypothesis, we compared the growth phenology and kinetics of Picea abies in the lower part of treeline ecotone between a north-facing slope with relatively nutrient-rich soils and a south-facing slope with nutrient-poor soils. We analysed intra-annual wood formation and its response to ambient climate, as well as soil and air microclimate and soil and needle nutrient content. Our results showed that thermal differences in treeline ecotones between south and north-facing slopes in temperate mountains are small but nontrivial involving higher daytime temperatures at south-facing slopes and longer irradiation of north-facing slopes during the middle part of growing season. The timing of growth onset and maximum growth rate were almost identical on both slopes. Accordingly, annual stem growth at both sites was most sensitive to the meteorological conditions at the start of the growing season and around the summer solstice. However, the absolute growth rate was higher on the north-facing slope, consistent with a higher availability and content of base cations in the soil and the needles. Our results suggest that temperature governs growth phenology at the lower part of the treeline ecotone, but nutrient availability modulates the growth rate in the peak season when temperature no longer limits cambial activity. We conclude that the effect of nutrient availability can be superior to the effect of slope aspect for stem growth rates of Picea abies located in the lower part of treeline ecotone in temperate mountain range.