A combined severe heatwave and drought, starting in 2018 and lasting for several months, restarted the discussion on the resistance of European beech to climatic changes, with severe growth reductions, early leaf senescence, leaf browning, and diebacks reported across Central Europe. These responses may result in long-term impacts such as reduced vitality of beech, especially under potential future drought periods. While the 2003 drought caused severe crown damage and defoliation and a loss in vitality, resulting in insect and fungal infestations and subsequent dieback, the drought in 2018 was even more severe in terms of geographical scale, duration, and intensity with reports of complete diebacks and severe mortality across Central Europe. These impacts were exacerbated in some regions by the consecutive drought in 2019 and secondary attacks from pathogens, as well as a further loss in vitality. Such enhanced drought exposure of beech trees could push them beyond their hydraulic safety margins. Moreover, growth legacy effects due to past droughts may lead to lower recovery over time, potentially leading to subsequent tree death. In order to better predict the future of beech growth and vitality in Central Europe, both short- and long-term legacy effects of defoliation and their influence on post-drought growth should be explored, and adaptive forest management strategies evaluated. Moreover, synergistic or additive interactions of legacy effects with drought, as well as with biotic disturbances, require further investigation. Long-term forest monitoring data facilitates investigations of drought responses of beech.

Frequency of drought years is expected to increase through climate warming. Mixed stands have often shown to be more productive than monospecific stands in terms of yield and of resistance against windthrows and bark beetle attacks. Mixture of beech and spruce is of particular interest. However, little is known about its growth reaction to drought. Therefore, we investigated the drought reaction of beech and spruce in mixed vs. monospecific stands along an ecological gradient. In particular, we sought evidence for mixture-related resilience on the individual tree level. Therefore, we quantified the response of tree ring width to drought. Moreover, we attempted to explain the relevance of individual tree response on the stand level by quantifying the stand level loss of volume growth after drought. At the individual tree level, beech was found to be more resilient and resistant in pure vs. mixed stands. Spruce, in contrast, was favored by mixture, and this was especially evident on drier sites. Along the gradient, growth losses at stand level increased in both mixed and pure stands in 2015, with growth gains on the drier sites observed in the same drought year, in accordance with the Stress Gradient Hypothesis. However, the stand level difference of growth loss between mixed and pure stands was not statistically significant. Mitigating mixture effects on the level of the individual tree thus did not become evident on the level of the whole stand.

Key message: A harmonized, comprehensive meteorological time series for 78 German intensive forest monitoring plots (Level II) has been made available from 1961 to 2019. The used hybrid spatial interpolation routine using simple linear regression and inverse distance weighting allows for gap filling of missing data and also for extrapolation outside measurement period to analyze long-term effects of climate on forest ecosystems. The dataset is available at https://www.openagrar.de/receive/openagrar_mods_00079174. The associated metadata are available at: https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/433a028f-dfc8-4a7c-82af-b8d7efafd724.

Micronutrient deficiency is widespread in alkaline soils of Pakistan which ultimately affect the yield and quality of sunflower oil. The current study was designed to investigate the combined as well as the sole effect of micronutrient application on the growth and yield attributes, and fatty acids profiling of selected sunflower hybrids. A field trial was conducted in sub-humid climatic conditions and two sunflower hybrids (FMC-1 and Parsun-3) were grown at the University of Haripur’s research farm. Micronutrients were applied through the foliar application at the start of the bud growing stage and before the flowering stage i.e., after 30 and 55 days of sowing. The application of micronutrients resulted in significant variation in agronomic parameters of sunflower hybrids. Molybdenum among the sole application and in combination treatments Zn, B, and Mo increased the growth traits of sunflower genotypes, while application of Zn and Mo (among sole application), and combination of Zn, B, and Mo increased the yield attributes. Oil content was highest in the combination of three micronutrients (Zn, B, and Mo) application followed by the Zn and B application individually. Sole micronutrients application also increased oil contents in both hybrids. Zinc application resulted in an increase of unsaturated fatty acids and a decrease in saturated fatty acids, while the B increased the oleic acid and stearic acid content and decreased the linoleic acid and palmitic acid contents. Among the varieties, FMC-1 has significantly achieved a higher yield than the Parsun-3. It is concluded from the research that Zn application increased the beneficial (poly- and mono-unsaturated) fatty acids and decreased the harmful (saturated) fatty acids. Zinc application @ 2 kg ha1 is recommended for good quality oil production.