Frequency of False Heartwood of Stems of Poplar Growing on Farmland in Sweden

Abstract

Swedish owners of poplar stands are interested in both the wood quality and the use of poplars that are soon to be harvested. An important concern is the frequency of false heartwood (FHW) in the stems. We have presented an overview of the factors causing discolored wood as well as the industrial use and quality of the end products. We have studied poplar stems growing at 22 sites in Sweden between latitudes 55° N and 60° N. The mean age of the poplar was 23 years (range 14-41), the mean stand density 1011 stems ha −1 (range 155-3493) and the diameter at breast height (DBH) (over bark) 246 mm (range 121-447). All stands were growing on clay soils (light and medium clay and light clay tills). All of the sampled stems (42) contained false heartwood. At 0%-50% of stem height, all sampled trees were discolored and at 90% of stem height, 33% were discolored. The percentage of false heartwood area by stem area was highest at 1% and 10% of stem height (26.6% and 24.7% respectively). The "FHW" part of the stem had a radius of 47 mm (range 9-93) at 30% of stem height, which corresponds to 50% of the total stem radius. A log of six meters represents about 30% of stem height. Equations describing the correlation between DBH and the diameter of FHW at different stem heights (1%, 10%, 30%, 50%, 70% and 90%) and table describing FHW volume % by total stem volume at the first 50% of stem height were constructed. These might be helpful for estimating the percentage of fresh wood in a stem. However, most of the fast-growing poplars will be harvested as biofuel.

Compartmentalization, Resource Allocation, and Wood Quality

“…Discolored cores were common in 20-year-old and older plantations established in abandoned farmland of a range of Populus species and hybrids in Sweden [49]. In this study, the transverse area of DW (termed "false heartwood") at DBH was not statistically related to poplar clone or soil type.…”

“…in woody stems, roots, and branches of otherwise light-colored wood tend to reduce the value of sawn timber for high-value wood products. Consequently, there is substantial research that attempts to relate the frequency of occurrence of DW in forest stands and the volume of DW within individual trees to environmental factors of climate, soil composition, and drainage [48][49][50][51].…”

Sawn timber and structural products from ‘Kawa’ poplar (Populus deltoides Marshall x P. yunnanensis Dode) grown in Northland, New Zealand

“…Corresponding values of heartwood percentage (on an area basis) ranged from 9.7% up to 76.3%, with a mean of 32.8%. There was no evidence of discoloured heartwood or "biological blackheart" which can occur in poplar (Johansson & Hjelm 2013). Sawlogs were sawn on a Wood-Mizer 3 mm kerf horizontal bandsaw into 25 mm and 50 mm slabs; slabs were then edged using a Wood-Mizer twin-blade edger (Wood-Mizer, Indianapolis, USA).…”

A protocol specialized for microbial DNA extraction from living poplar wood

“…Poplar is one of the most fast-growing timber species in the northern hemisphere, but wetwood occurred seriously and adversely affected its wood processing and utilization (Johansson and Hjelm, 2013;Wang et al, 2008). Wetwood, a worldwide disease, is a kind of abnormal phenomenon of heartwood during tree growth (Jeremic et al, 2004;Martin et al, 2021), with characteristics of high moisture contents, deep color, rot, and acid or alkaline pH value of the extract, as well as alterative physical and chemical wood properties etc.…”

“…Till now, the dominant factors of onset of wetwood are still unclear. But most scholars considered pathogenic microorganisms played an important role in wetwood formation (Johansson and Hjelm, 2013). A lot of studies on endophytic bacterial communities have been carried out, and many types of bacteria have been isolated from living wetwood based on traditional method of tissue culture, such as Xanthomonas, Agrobacterium, Corynebacterium, and Erwinia etc.…”