Physiological vitality of Norway spruce (Picea abies L.) stands along an altitudinal gradient in Tatra National Park

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.

Soil Respiration after Bark Beetle Infestation along a Vertical Transect in Mountain Spruce Forest

“…The studied site is dominated by Norway spruce (Picea abies (L.) Karst.) with a few other coniferous tree species mentioned in a previous study [58]. Since 2011, the area has been affected by an attack from the European spruce bark beetle (Ips typographus L.).…”

“…Since 2011, the area has been affected by an attack from the European spruce bark beetle (Ips typographus L.). Spruce forests above 1300 m in elevation are considered natural old-growth, while those below this zone are classified as semi-natural spruce forests due to frequent wind damage, resulting in a higher proportion of successional trees [58]. We measured SR five to six years after the initial bark beetle attack because SR is one of the ecological parameters measured on five-year cycles at the LTER sites (long-term ecological research) [59].…”

“…The undisturbed forest in the area ranged from 100 to 165 years old, with stocking density varying from 0.4 to 0.8. A windthrow event in 2014 at 1200 m above sea level caused a decrease in stocking density to 0.4 [58]. The understory vegetation primarily consisted of acidophilic plants, particularly bilberry (Vaccinium myrtillus).…”

“…Infested plots were characterized by no living trees with already shaded needles, and the understory was represented by successional grasses and perennials fully covering the soil. More detailed information about the study area can be found in the mentioned study [58].…”

Post-disturbance Dynamics of Soil Respiration in the High Tatra Mts. (Slovakia)

“…The studied site is dominated by Norway spruce (Picea abies (L.) Karst.) with the contribution of a few coniferous tree species described in [35] and was affected by European spruce bark beetle (Ips typographus L.) attack since 2011. The research area was established on the boundary between undisturbed and bark beetle infested areas (standing dead trees) and encompasses an elevation gradient from 1100 to 1400 m a.s.l.…”