The effects of artificial soil frost on cambial activity and xylem formation in Norway spruce

Abstract

We studied the effects of artificial soil frost on cambial activity and xylem formation on 47-year-old Norway spruce [Picea abies (L.) Karst.] trees grown on medium fertile site type (with moraine soil) in eastern Finland (62°42 0 N; 29°45 0 E). Different soil frost treatments applied were: (1) natural snow accumulation and melting (control, CTRL); (2) artificial removal of snow from soil surface during two consecutive winters (OPEN); and (3) snow clearing and insulation (FROST), which was in other ways similar to OPEN, but the ground was insulated in early spring to delay soil thawing. Each treatment was replicated in three blocks, and two sample trees in each plot were repeatedly microcored during growing seasons of 2006-2007 for the analysis of the onset, cessation and the duration of xylem formation. The phases of tracheid differentiation (tracheids in radial enlargement, secondary cell wall formation, and mature tracheids) were measured from the microcores of 2007. The intra-ring growth and wood density variables were analysed based on X-ray densitometry. In FROST in 2006, xylem formation started a week later than in the other treatments. In 2007, no difference was found between the treatments. The discrepancy in results between the two study years may be explained by between-years variation in weather, i.e., the winter was colder in 2005/2006 than in 2006/2007. No effects of soil frost treatments on tracheid differentiation and on most of the intra-ring growth and density variables were discovered. Our results suggest that the delayed thawing of moraine soil may slightly affect the onset, timing and duration of xylem formation in Norway spruce. However, the effects of delayed soil frost may depend also on the soil type and become more evident with increasing water holding capacity of the soil.

Thinning increases climatic resilience of red pine

“…A potential ecophysiological-based explanation for this is that more snow is able to reach the ground of the high thinning intensity plots, insulating the soil by a few extra degrees (Brown and DeGaetano 2011). Greater soil temperature leads to earlier growth initiation in the spring and reduces the incidences of xylem cavitations in frozen tissue (Jyske et al 2012). Furthermore, greater snow pack in the winter could drive increased soil moisture in the spring.…”

Vegetative buds, needles and shoot growth of Norway spruce are affected by experimentally delayed soil thawing in the field

“…Snow depth on the CTRL plots was monitored. For more details of the study design see Maljanen et al (2010), Repo et al (2011) and Jyske et al (2012).…”

“…Sap flow and stomatal conductance decreased and photosynthetic recovery was delayed in 20-year-old Scots pine (Mellander et al, 2004(Mellander et al, , 2008. Furthermore, the delayed soil thawing delayed starch accumulation in needles (Repo et al, 2011), delayed formation of new tracheid cells in trunks (Jyske et al, 2012) and hampered the fine root formation and increased root mortality in 47-year-old Norway spruce in Eastern Finland . The laboratory experiments have shown negative impacts of delayed soil thawing on needle physiology as well as on growth of fine roots and root tip formation in Scots pine saplings (Repo et al, 2005(Repo et al, , 2008.…”

Long-term summer sunshine/moisture stress reconstruction from tree-ring widths from Bosnia and Herzegovina

“…2). This means that extremely cold winters could affect the cambium and limit its activity (Jyske et al, 2012). In such years TRW could be narrower, despite the possible good growth conditions later in the summer.…”