Environmental factors affecting formation of lammas shoots in young stands of Norway spruce (Picea abies Karst.) in Latvia

Abstract

Norway spruce is a relatively fast-growing tree species that is primarily regenerated by planting, which requires significant investments. The formation of lammas shoots (i.e., second flushing in late summer) have been proven to affect the quality and productivity of Norway spruce stands. The aim of our study was to assess the proportion of trees with lammas shoots in young stands of Norway spruce and to investigate the factors affecting their formation. Data have been collected at the end of 2011 in 102 three-to seven-year-old Norway spruce plantations randomly selected across different forest types in the central part of Latvia, and a subset of 21 stands were inventoried again at the end of 2012. In each stand, 20 sample plots were systematically established where trees with and without lammas shoots were counted and micro-environmental factors (moisture, competition, and browsing) were assessed on a three-grade scale.On average, the proportion of trees with lammas shoots was 6.5%. There was no significant effect of the stand age (from 3 to 7 years) on the proportion of trees with lammas shoots nor was there any age-related trend. The effect of forest type on the presence of lammas shoots was not significant. Micro-environmental factors had an important influence on the proportion of trees with lammas shoots. The proportion of lammas shoots in stands with no competition was significantly higher (14.5%) compared to stands with medium and high competition (6.0% and 2.2%, respectively). Similarly, a significantly higher proportion of trees with lammas shoots (11.7%) was observed in sites with normal moisture regime than in sites with slight or notable excess moisture, reaching 4.8% and 1.7%, respectively. Although the influence of browsing damage was not statistically significant, its trend was similar to that observed for competition and moisture regime. Overall, the proportion of trees with lammas shoots was highest in stands showing the most suitable micro-environmental conditions for Norway spruce.

Influence of drainage reconstruction on radial increment of conifers: case study

“…It might be both related to the shade tolerance (also higher density stand trees react to the improved conditions) as well as to higher sensitivity to excess water for Norway spruce. Such sensitivity had been demonstrated both for radial (Jansons et al, 2016b) and height increment for trees at different age, including on formation of lammas growth at the end of the vegetation season (Katrevics et al, 2018). Figure 2.…”

“…Similarly, a relatively long-lasting influence of fertilization, has been observed of the tree species (Jansons et al, 2016a). The increment (productivity) of the trees can be even further raised by influence of climate in combination with changes in silviculture e.g., tailored soil preparation, tending, different stand density Katrevics et al, 2018;Katrevičs et al, 2018). Also, application of tree breeding results, currently a very common practice for Scots pine (mostly planted, all plants grown from seed orchard seeds) and Norway spruce (almost exclusively planted, most of plants form seed orchard seeds), can substantially increase the growth (Jansons, Gailis, & Donis, 2011;Jansons et al, 2015a).…”

Carbon Pools in Old-Growth Scots Pine Stands on Organic Soils and Its Concentration in Deadwood: Cases Study in Latvia

“…Even so the most intensive forest management (whole tree biomass harvesting) does not leave permanent negative effect on forest ecosystem (Jansons et al, 2016) it still changes the dominant age class of trees and leaves a long-lasting impact on forest legacies (Jogiste et al, 2018). Both the growth of trees as well as frequency and severity of disturbancesthus tree mortalitywill be (are) affected by climate changes (Katrevics et al, 2018, Matisone et al, 2019. Large-scale natural disturbances as well as single-tree mortality is a source of deadwood.…”

Post-storm regeneration of Norway spruce

“…One of such measures is fertilization that has a long-lasting impact on the growth (diameter increment) of Norway spruce (Jansons et al, 2016a). Further capacity of trees to increase the growth can be possible (Katrevics et al, 2018;Katrevičs et al, 2018) both due to the changes in silviculture as well as longer growing period (Krišāns et al, 2016). Continuous rapid changes in climate might lead to limits of phenotypic plasticity of adaptation (Schmidt-Vogt, 1977).…”