Effects of knife-incising and longitudinal kerfing pretreatments on high-temperature drying of red pine and pitch pine timbers

Effects of knife-incising and longitudinal kerfing pretreatments were analyzed relative to the high-temperature drying of red pine and pitch pine timbers with cross-sections less than 15 cm. Specimens were prepared as round and square timbers with thicknesses of 9, 12, and 15 cm. They were divided into four groups: control, longitudinal kerf, knife-incised, and a combination of knife-incised and longitudinal kerf. Some results from this study, such as commercial availability and application methods of drying schedules, have immense commercial importance. The incising and kerfing treatment can be used not only to improve drying quality but also as a tool for deriving an optimal drying schedule. The kerfing treatment noticeably reduced the surface checks in square timber. However, the incising treatment caused a phenomenon in which the incisions connect to each other and develop into surface checks. The wood characteristics, such as species, type, thickness, and initial MC, had more influence on determining the drying defects than the pretreatments. For the commercial use of the drying schedule used in this study, it can be useful to determine the appropriate drying time in the third step according to the species, thickness, and shape.

Preliminary Evidence that Intraspecific Competition Increases Size of Restoration-Planted Pitch and Shortleaf Pines in a Mixed-Hardwood Clearcut in the Southern Appalachians

Oak-pine (Quercus L. - Pinus L.) forest communities on low ridges in the southern Appalachian Mountains are losing diversity as mature pitch (P. rigida Mill.) and shortleaf (P. echinata Mill.) pines die and do not regenerate under a hardwood canopy. Restoration of biodiversity by planting pine seedlings is well known, but little is known regarding whether the configuration of planted seedlings affects growth and subsequent size (diameter at breast height, dbh) as trees age. The purpose of this study was to test the hypothesis that pines growing in groups of two or more trees respond with increased growth (expressed by dbh) to intraspecific competition with other pines compared to single trees subjected only to interspecific competition with surrounding hardwoods. For 13-year-old pitch and shortleaf pines, trees were larger in dbh when occurring in groups than trees occurring singly. Regression indicated that intraspecific competition accounted for 16% of the dbh variation of pitch pine and 29% for shortleaf pine. This study originated from chance observations in a small study of pine restoration. If a designed study confirms these results, resource managers could restore biodiversity with reduced site disturbance and establishment costs by planting pine seedlings in small groups rather than rows.

Diurnal Pine Bark Structure Dynamics Affect Properties Relevant to Firebrand Generation

Firebrands are an important agent of wildfire spread and structure fire ignitions at the wildland urban interface. Bark flake morphology has been highlighted as an important yet poorly characterized factor in firebrand generation, transport, deposition, and ignition of unburned material. Using pine species where bark flakes are the documented source of embers, we conducted experiments to investigate how bark structure changes in response to diurnal drying. Over a three-day period in a longleaf pine (Pinus palustris Mill.) stand in Florida, we recorded changes in temperature, moisture content, and structure of bark across different facing aspects of mature pine trees to examine the effects of varying solar exposure on bark moisture. We further compared results to bark drying in a pitch pine (Pinus rigida Mill.) plantation in New Jersey. Under all conditions, bark peeled and lifted away from the tree trunk over the study periods. Tree bole aspect and the time of day interacted to significantly affect bark peeling. General temperature increases and moisture content decreases were significantly different between east and west aspects in pitch pine, and with time of day and aspect in longleaf pine. These results illustrate that bark moisture and flakiness is highly dynamic on short time scales, driven largely by solar exposure. These diurnal changes likely influence the probability of firebrand production during fire events via controls on moisture (ignition) and peeling (lofting).

Diurnal Pine Bark Structure Dynamics Affect Properties Relevant to Firebrand Generation

Firebrands are an important agent of wildfire spread and structure fire ignitions at the wildland urban interface. Bark flake morphology has been highlighted as an important, yet poorly characterized factor in firebrand generation, transport, deposition, and ignition of unburned material. Using pine species where bark flakes are the documented source of embers, we conducted experiments to investigate how bark structure changes in response to diurnal drying. Over a 3-day period in a longleaf pine (Pinus palustris Mill.) stand in Florida, we recorded changes in temperature, moisture content and structure of bark across different facing aspects of mature pine trees to examine the effects of varying solar exposure on bark moisture. We further compared results to bark drying in a pitch pine (Pinus rigida Mill.) plantation in New Jersey. Under all conditions, bark peeled and lifted away from the tree trunk over the study periods. Tree bole aspect and the time of day interacted to significantly affect bark peeling. General temperature increases and moisture content decreases were significantly different between east and west aspects in pitch pine, and with time of day and aspect in longleaf pine. These results illustrate that bark moisture and flakiness is highly dynamic on short time scales, driven largely by solar exposure. These diurnal changes likely influence the probability of firebrand production during fire events via controls on moisture (ignition) and peeling (lofting).

Assessment of Restoration Effects and Invasive Potential Based on Vegetation Dynamics of Pitch Pine (Pinus rigida Mill.) Plantation in Korea

During the period of Japanese occupation (1910–1945) and the Korean War (1950–1953), extensive areas of forest were severely degraded by over-harvesting and fire in Korea. In addition, intensive use of the forest-resources to obtain fuel, organic compost, livestock feed, and so on contributed to forest degradation. As a result, the South Korean government launched large-scale tree planting projects to reforest the denuded mountains particularly in the 1960s. This study aims to evaluate the restoration effects of the pitch pine (Pinus rigida Mill.) plantations and further diagnose the invasive potential of the pitch pine. To arrive at the goals, we investigated the changes of vegetation and soil characteristics in different chronosequences in the pitch pine plantations and in native forests, which were selected as reference stands. Pitch pine plantations were usually planted on mountainous land, which is characterized by an elevation of below 300 m above sea level and a gentle slope below 20°. The species composition of the pitch pine forestations was different depending on the study site but tended to resemble that of the reference stands in the years after forestation. The species diversity showed an increasing trend in response to stand age. The frequency distribution of diameter classes of dominant tree species showed a trend for pitch pine plantations to succeed to native oak stands. A change in canopy profiles depending on stand age also proved the successional trend. The establishment and development of pitch pine plantations for reforestation contributed to erosion control and improved the physic-chemical properties of the soil and thus prepared a basis for the recovery of native vegetation. Such changes in vegetation and soil confirmed that the pitch pine plantations successfully achieved the restoration goals. On the other hand, mature pitch pine stands reproduced young pitch pine stands by self-seeding on the slopes of various sorts of roads including expressways. This shows that pitch pine is successfully established in Korea and thereby the species has been naturalized. However, the natural succession of pitch pine stands in Korea suggests that it is possible to introduce some exotic species for reforestation without resulting in uncontrolled invasion.

Comparing the Physicochemical Properties of Upgraded Biomass Fuel by Torrefaction and the Ashless Technique

The purpose of this study was to investigate and compare the influence of torrefaction and an ashless process on the physical and chemical properties of pitch pine sawdust (PSD) and kenaf as types of woody and herbaceous biomass. The physicochemical properties of the materials pretreated by the ashless process with torrefaction including proximate and ultimate analysis, hydrophobicity, grindability, morphology, and structure were analyzed. The results showed that when ashless Kenaf was torrefied, the high heating rate and atomic ratios of O/C and H/C increased. The tendency of the torrefied, ashless Kenaf to absorb water decreased, and it became more hydrophobic (approximately 0% for the uptake rate of moisture). In addition, the grindability of the torrefied, ashless Kenaf was substantially improved compared to that of pretreated PSD. Brunauer–Emmett–Teller and scanning electron microscopy results showed that when Kenaf was pretreated, particles easily lost their fibrous structure and cracked as the number of macropores decreased. These results indicate that the herbaceous biomass of Kenaf, when pretreated with both torrefaction and the ashless process, exhibits improved physicochemical properties compared to the woody PSD.