Fire history and dendroecology of Catoctin Mountain, Maryland, USA, with newspaper corroboration

Background Our study was designed to reveal a detailed forest fire history at Catoctin Mountain Park, Maryland, USA. We compared the ages of living trees to known fire dates in the dendrochronological record. Seasonality and years of fires in the dendrochronological record were juxtaposed with specific dates of fires recorded in newspapers. Results Twenty-seven pines (Pinus L.) captured 122 fire scars representing 58 distinct fire years between 1702 and 1951. Climate was significantly hotter and drier in the years of burns that affected at least two trees and was wetter two years prior. Thirty-three fires described in local newspapers were reported largely in the spring and fall months (68% between March and June, 32% between September and December). Ninety-one percent of fire scars in our tree-ring chronology had dormant seasonality. The mean fire interval was 5.47 ± 10.14 (SD; standard deviation) yr, and the Weibull median fire interval was 3.22 yr during the entire chronology. The longest fire-free interval was from 1952 to 2018. The size structure of living trees was biased toward smaller black gums (Nyssa sylvatica Marshall) and oaks (Quercus L.) that recruited in the 1930s and 1940s. Most living pitch pines (Pinus rigida Mill) recruited between 1890 and 1910, but a few individuals recruited before the 1850s. Diversity of tree stems smaller than 10 cm diameter at breast height (DBH) was generally lacking; the youngest tree >10 cm DBH in our study area had recruited by 1967. Conclusions The Catoctin Mountains experienced frequent fire during the 1800s and early 1900s. The causes of fires were diverse, including accidental ignitions and purposeful cultural burning for berry (Vaccinium L.) production. The current forest developed during a period of low deer density and after the demise of the charcoal iron industry ended an era of logging. The lack of fire since the 1950s has encouraged the development of a black gum dominated mid- and understory. Management with frequent fire would facilitate pine and oak regeneration.

Using plant extractives as eco-friendly pulp additives: Mechanical and antifungal properties of paper sheets made from linen fibers

In this study, extractives from Pinus rigida heartwood (PRW), Eucalyptus camaldulensis var. obtusa aerial parts (ECL), and Eucalyptus flower buds (ECF) were used as additives in paper sheets produced from the pulp of linen fibers, and their effects on the mechanical and antifungal properties of the paper sheets were studied. The highest tensile and tear indices were 31.5 Nm/g, and 17.3 mNm2/g as pulp treated with PRW (4%), and ECL (1%), respectively. All the pulp additives yielded lower burst index values compared to the control (2.24 KPa.m2/g); the nearest value was 2.23 KPa.m2/g (ECL 4% pulp additive). The brightness percentages (ISO%) ranged from 65.7% to 70.2%, which were lower than the control treatment (70.3%). The paper sheets produced from pulp treated with 2% or 4% PRW, and with 4% ECL suppressed Aspergillus niger growth on the paper disc; pulp treated with 2% or 4% PRW, 4% ECL, and with 2% or 4% ECF completely suppressed A. terreus growth. However, all pulp extract additives did not inhibit the growth of Fusarium culmorum.

Characterizing the Interception Capacity of Floor Litter with Rainfall Simulation Experiments

Floor litter can reduce the amount of water reaching the soil layer through rainfall interception. The rainfall interception capacity of floor litter varies with the physical features of the litter and rainfall characteristics. This study aimed to define the maximum and minimum interception storages (Cmx, Cmn) of litter layers using rainfall simulation experiments, and examine the effects of litter type and rainfall characteristics on rainfall retention and drainage processes that occur in the litter layer. Different types of needle-leaf and broadleaf litters were used: Abies holophylla, Pinus strobus, Pinus rigida, Quercus acutissima, Quercus variabilis, and Sorbus alnifolia. Our results indicate a wide variation in interception storage values of needle leaf litter, regardless of the rainfall intensity and duration. The A. holophylla needle-leaf litter showed the highest Cmx and Cmn values owing to its short length and low porosity. Conversely, the lowest interception storage values were determined for the P. strobus needle leaf litter. No significant differences in interception storage were established for the broadleaf litter. Moreover, except for A. holophylla litter, the broadleaf litter retained more water than the needle leaf litter. An increase in the intensity or duration of rainfall events leads to an increase in the water retention storage of litter. However, these factors do not influence the litter’s drainage capacity, which depends primarily on the force of gravity.

Pygmaeomycetaceae, a new root associated family in Mucoromycotina from the pygmy pine plains

ABSTRACTA new genus, Pygmaeomyces, and two new species are described based on phylogenetic analyses, phenotypic and ecological characters. The species delimitation was based on concordance of gene genealogies. The Pygmaeomyces cultures were isolated from the roots of mountain laurel (Kalmia latifolia) and pitch pine (Pinus rigida) from the acidic and oligotrophic New Jersey Pygmy Pine Plains; however, they likely have a broader distribution because their internal transcribed spacer (ITS) sequences have high similarity with a number of environmental sequences from multiple independent studies. Based on the phylogeny and phenotypical characters, a new family Pygmaeomycetaceae is proposed to accommodate this new lineage in Mucoromycotina. Pygmaeomycetaceae corresponds to Clade GS23, which was identified based on a sequence-only soil fungal survey and was believed to be a distinct new class. Compared to the culture-based methods, we observed that sequence-only analyses tend to over-estimate the taxonomic level. Results from this work will facilitate ecological and evolutionary studies on root-associated fungi.

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.

Comparison of Allometric Equation and Destructive Measurement of Carbon Storage of Naturally Regenerated Understory in a Pinus rigida Plantation in South Korea

The forest understory plays an important role in the carbon and nutrient cycling and forest stability, but cost-efficient quantification of its biomass remains challenging. Most of the existing biomass allometric equations have been developed and designed only for mature forest trees (i.e., Diameter at breast height (DBH) ≥ 10 cm), and those for trees with DBH less than 10 cm are not readily available. In this study, we compared the biomass by plant component (i.e., foliage, branch, and stem) measured by a destructive method with those estimated by the existing biomass allometric equations for understory trees with DBH less than 10 cm in a Pinus rigida plantation. We also developed an allometric biomass equation for the identified understory tree species, namely, Quercus variabilis, Quercus acutissima, Quercus mongolica, Quercus serrata, and Carpinus laxiflora. The estimated biomass using allometric equations for foliage, branch, and stem was lower than the values obtained using the destructive method by 64%, 41%, and 18%, respectively. The biomass allometric equations developed in this study showed high coefficients of determination (mean R2 = 0.970) but varied depending on species and tree part (range: 0.824–0.984 for foliage, 0.825–0.952 for branch, and 0.884–0.999 for the stem, respectively). The computed biomass of the understory vegetation was 22.9 Mg ha−1, representing 12.0% of the total biomass of the P. rigida plantation. The present study demonstrates that understory trees with DBH less than 10 cm account for a considerable portion of carbon stock in forest ecosystems, and therefore suggests that more biomass allometric equations should be optimized for small-DBH trees to improve forest carbon stock estimation.

Assessment of efficacy and effectiveness of some extracted bio-chemicals as bio-fungicides on wood

The present study investigates in-vitro the antifungal activity of two extracts (ethyl ether extracts of Schinus terebinthifolius ripened fruits and Pinus rigida heartwood) and two essential oils (Thymus vulgaris and Origanum majorana leaves) against two species of fungi; Trichoderma harzianum and Aspergillus niger. The results clearly show that O. majorana oil and P. rigida wood extract had the highest activity against both fungi and were chosen for the application on four wood species; Weeping-Wreath Wattle (Acacia saligna), Beech (Fagus sylvatica), Black Walnut (Juglans nigra) and Pitch Pine (Pinus rigida). Additionally, their impact on the wood structure was examined by FTIR, SEM and colorimetry. The study suggests that O. majorana oil appears to show the best results and could be used as friendly bio-fungicides to protect wood objects without changing their structures.