Nutrient status of Norway spruce stands subjected to different levels of overstorey removal

Abstract

Foliage nutrient concentrations of overstorey and understorey Norway spruce [Picea abies (L.)Karst.], and height growth and needle weights of understorey saplings, were studied in a 7-year period after harvest. The following treatments were applied on each of three sites 5 years prior to needle sampling: control with no cutting, partial cutting with 50-60% removal of basal area, and patch cut (25×25 m -0.063 ha clear-cut). Saplings on control plots had higher concentrations of K and Cu in current-year needles (C) than overstorey trees. Increased harvest intensity led to a reduction of K in C needles and Mg in (C+1) needles of saplings, and of B in both saplings (C, C+1) and overstorey trees (C+1). Sapling needle weights generally increased with harvest intensity, whereas no effect of foliage N status on needle weights could be detected. The growth response of saplings was explained by the interaction between foliage N status, quantified as average N concentration in C and (C+1) needles, and harvest intensity. The results illustrate that sufficient N supply is a key factor for the ability of advance regeneration to utilise the improved light condition associated with overstorey removal.

Effect of harvest intensity on development of natural regeneration and shrubs in an Ontario boreal mixedwood stand

“…Partial cutting to release conifer saplings may not be appropriate on nutrient-poor sites, because understory conifers require sufficient nitrogen to utilize higher light levels (Granhus and Braekke, 2001). This may be an important consideration on sites with aspen competition because suckers have access to carbohydrate reserves in the parent root system.…”

Temporal Effects of Thinning on the Leaf C:N:P Stoichiometry of Regenerated Broadleaved Trees in Larch Plantations

“…The leaf N concentrations increased under lower light conditions [63,64], so the leaf N concentrations increased from a short term to a medium term after thinning. In addition, the leaf N concentration was positively related with the soil N and N:P ratios ( Table 2), which inferred a strong interaction between soil and understory regeneration [14,65]. The highest soil N concentrations in the medium-term stands may have also contributed to the highest leaf N concentration, while in the long term after thinning, the lower leaf N may be caused by the increases in crown biomass [66].…”

“…The establishment and growth of broadleaved tree species is a crucial step in the natural regeneration processes [11], and it is strongly restricted by environmental factors, e.g., the light environment and soil nutrients [12,13]. Plants can change leaf physiological traits following the growing conditions, and this rapid adjustment may depend on the nutrient status, especially the C:N:P stoichiometry [14,15]. For example, at lower light conditions, there are higher N and P concentrations in the leaves of plants [16,17], while at lower soil N and P conditions, plants tend to have lower leaf C:N and C:P ratios to enhance nutrient utilization efficiency [18,19].…”

Natural Regeneration in a Multi-Layered Pinus sylvestris-Picea abies Forest after Target Diameter Harvest and Soil Scarification

“…Only a southern site in central Sweden [4] showed comparable annual height growth rates that ranged from 1-19 cm on average. In addition, further increases in height growth rates can be expected in subsequent years given results reported from older experiments [12,13].…”