Abstract
Abstract Nowadays, a large area of Norway spruce forest stands in Europe is disturbed by windstorm and, subsequently, bark beetle outbreaks. We investigated the state of three disturbed spruce stands along an altitudinal gradient in Tatra National Park (Slovakia) through various physiological processes. Tree-growth characteristics, the mineral nutrition in the needles, and photosynthetic efficiency were assessed. Two techniques of chlorophyll a fluorescence and analyses of assimilatory pigments were used to detect the changes in photosynthesis functioning. Also, the heat sensitivity of photosystem II was tested. Our results showed that these stands are located in nutrient-poor environments. We recorded similar contents of nitrogen, phosphorus, potassium, sodium, zinc, and iron in all stands. Down the vertical transect, the contents of calcium, magnesium, and manganese significantly decreased and the non-essential aluminium increased. Based on stem circumference measurements, water deficit occurred during the vegetation season in all stands, but with the smallest magnitude highest U–stand. We found some photosynthetic constraints: slightly lower chlorophyll contents in all stands were recorded; however, seasonal dynamics with increasing chlorophyll concentration in the highest U–stand were observed. Moreover, the photochemistry of the lowest D–stand was the most negatively influenced by simulated heat, as the photosynthetic performance index, and the density of the active reactions centres significantly decreased and the values of the K–step and basal fluorescence increased. Therefore, we can conclude the different levels of physiological vitality in these naturally damaged spruce stands, with the best physiological performance of the trees in the highest stand.
Highlights
In the context of climate and environmental change, the growth and vitality of Norway spruce, a dominant component of European mountains, may be called into question
Using the data from three forest stands affected by a windstorm in 2004 and subsequently damaged by spruce bark beetles, we identified the tree-growth characteristics and the mineral nutrition in the needles, as well as explored variations in the photosynthetic efficiency through quantitative and qualitative analyses of photosynthetic pigments and chlorophyll a fluorescence
The main objectives of this study were: (1) To evaluate the changes in the stem circumference of spruce stands along the transect; (2) to compare the state of the mineral nutrition and contents and ratios of assimilatory pigments in the needles; (3) to test the photosystem II (PSII) performance and thermostability using two fluorescence techniques, namely slow kinetics–rapid light curves (RLCs)–and fast kinetics of Chlorophyll a (Chl a) fluorescence; and (4) to investigate how the assimilatory pigments and Chl a fluorescence vary during the season in spruce forests of different vitality levels
Summary
In the context of climate and environmental change, the growth and vitality of Norway spruce, a dominant component of European mountains, may be called into question. Due to the increased scale of weather extremes and other damaging agents, the health status of spruce stands has considerably worsened in the whole Central European region (Uniyal & Uniyal 2009; Allen et al 2010; Lindner et al 2014). Climate-induced physiological stress and interactions with other processes, such as natural disturbances and insect pest gradations, can lead to the mortality of whole spruce populations and can create a major change in forest communities. Windstorms and bark beetles (Ips typographus and Pityogenes chalcographus) have been the most damaging agents for spruce stands in Slovakia within the last two decades.
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