Anatomical and Morphological Features of Scots Pine Heartwood Formation in Two Forest Types in the Middle Taiga Subzone

Abstract

Currently, there is no consensus on how growing conditions affect the heartwood formation in Scots pine. Comparing the results obtained by different authors is difficult due to methodology differences and poor descriptions of the objects used. We selected two sample plots in (1) a blueberry pine forest on nutrient-rich and moist soil and (2) a lichen pine forest on nutrient-poor and dry soil and performed their detailed characterization. The sample plots were located 22 km apart in the middle taiga subzone (Karelia Republic, northwest Russia). In each sample plot, we selected five dominant trees (model trees), from which we took cores at different trunk heights (0.3, 1.5, 4.5, 7.5 and 10.5 m). The cores were treated with 2,6-dichlorophenolindophenol to identify the heartwood zone. Additionally, samples were taken to study the structural features of the transition zone between sapwood and heartwood. In both forest types, the number of heartwood rings depended on the cambium age, and the patterns of parenchyma cell death did not differ in the transition zone. These facts point to a predominantly internal regulation of the heartwood formation in Scots pine. The heartwood radius and its proportion on the cross-sections were significantly higher in the blueberry pine forest than in the lichen pine forest, despite the relative values of the annual ring width. Further research is needed to develop successful Scots pine heartwood width models under a wide range of conditions.

Heartwood Relationship with Stem Diameter in Pinus canariensis Plantations of Gran Canaria, Spain

“…While we estimated climatic conditions at the sampled plots using topographically derived variables, and found no significant correlations, other studies have indicated that climate can influence heartwood formation in both conifers [72,73] and angiosperms [74]. For teak (Tectona grandis) grown in India, wet sites yielded larger heartwood than dry sites [75], whereas the opposite case was found for teak planted in Ghana [76].…”

Water, starch, and nuclear behavior in ray parenchyma during heartwood formation of Catalpa bungei ‘Jinsi’

“…We attempt to correlate structural observations on different xylem tissues with starch grains, water distribution, and nuclei availability ( Table 2 ). However, correlation did not explain the causes of HW formation involving many interconnected anatomical, chemical and physiological processes [ 18 , 23 , 53 ]. Future studies should track extractives across the xylem to better understand where extractives are formed.…”

“…The above studies indicate no sudden transition from SW to HW. Therefore, scientists present a theme focusing on the transition zone (TZ) between HW and SW in trees [ [21] , [22] , [23] ].…”

Developing a Model for Curve-Fitting a Tree Stem’s Cross-Sectional Shape and Sapwood–Heartwood Transition in a Polar Diagram System Using Nonlinear Regression

“…Contrast color indicates higher extractive content, significantly improving the wood's natural durability. The degradation and incrustation of pores in the xylem vascular elements with extractive substances accompany heartwood formation, significantly reduce wood permeability, lead to water transport cessation, and prevent wood-decaying organism penetration [41][42][43]. Scented extractive substance contents in heartwood, namely, terpenoids (i.e., monoterpenoids and sesquiterpenes), are synthesized, accumulated, and shaped for fragrance formation [44].…”