Connect four on trees

The physiological characteristics of trees change with age, suggesting that growth-related climate signals vary over time. This study aimed to clarify the impacts of different diameter classes on the chronological characteristics of Pinus massoniana Lamb. and its response to climatic factors. Chronologies of Pinus massoniana were established in small diameter (14.1 cm), middle diameter (27.3 cm), and large diameter (34.6 cm) trees according to dendrochronology. The results show that: (1) radial growth of different diameter classes had varied characteristics and climate sensitivities; (2) radial growth of small diameter trees was affected by climatic factors of the previous and the current year, while large diameter trees were mainly affected by climatic factors of the current year; and (3) precipitation and temperature were key factors that restricted the radial growth of small and large diameter trees, respectively.

Orthogonal double covers of complete graphs by trees of small diameter

Case Study: Economic viability of producing animal bedding from low quality and small diameter trees using a wood shaving machine

Formulating allometric equations for estimating biomass and carbon stock in small diameter trees

Thousand cankers disease, caused by the invasive bark beetle Pityophthorus juglandis Blackman and an associated fungal pathogen Geosmithia morbida M.Kolařík, E. Freeland, C. Utley, N. Tisserat, currently threatens the health of eastern black walnut (Juglans nigra L.) in North America. Both the beetle and pathogen have expanded beyond their native range via transport of infested walnut wood. Geosmithia morbida can develop in seedlings following inoculation, but the ability of P. juglandis to colonize young, small diameter trees has not been investigated. This study assessed the beetle’s colonization behavior on J. nigra nursery trees. Beetles were caged directly onto the stems of walnut seedlings from five nursery sources representing a range of basal stem diameter classes. Seedlings were also exposed to P. juglandis in a limited choice, field-based experiment comparing pheromone-baited and unbaited stems. When beetles were caged directly onto stems, they probed and attempted to colonize seedlings across the range of diameters and across sources tested, including stems as small as 0.5 cm in diameter. In the field experiment, beetles only attempted to colonize seedlings that were baited with a pheromone lure and appeared to prefer (though not statistically significant) the larger diameter trees. Despite several successful penetrations into the phloem, there was no evidence of successful progeny development within the young trees in either experiment. Further investigation is recommended to better elucidate the risk nursery stock poses as a pathway for thousand cankers disease causal organisms.

We used 20-mm-long, Granier-type sensors to quantify the effects of tree size, azimuth and radial position in the xylem on the spatial variability in xylem sap flux in 64-year-old trees of Taxodium distichum L. Rich. growing in a flooded forest. This information was used to scale flux to the stand level to investigate variations in half-hourly and daily (24-hour) sums of sap flow, transpiration per unit of leaf area, and stand transpiration in relation to vapor pressure deficit (D) and photosynthetically active radiation (Q(o)). Measurements of xylem sap flux density (J(s)) indicated that: (1) J(s) in small diameter trees was 0.70 of that in medium and large diameter trees, but the relationship between stem diameter as a continuous variable and J(s) was not significant; (2) J(s) at 20-40 mm depth in the xylem was 0.40 of that at 0-20 mm depth; and (3) J(s) on the north side of trees was 0.64 of that in directions 120 degrees from the north. Daily transpiration was linearly related to daily daytime mean D, and reached a modest value of 1.3 mm day(-1), reflecting the low leaf area index (LAI = 2.2) of the stand. Because there was no soil water limitation, half-hourly water uptake was nearly linearly related to D at D < 0.6 kPa during both night and day, increasing to saturation during daytime at higher values of D. The positive effect of Q(o) on J(s) was significant, but relatively minor. Thus, a second-order polynomial with D explained 94% of the variation in J(s) and transpiration. An approximately 40% reduction in LAI by a hurricane resulted in decreases of about 18% in J(s) and stand transpiration, indicating partial stomatal compensation.

We explored the differences in the impacts of drought events on Pinus sylvestris var. mongolica of different ages (30 and 40 years) and different diameter classes (large 20-24.9 cm, medium 15-19.9 cm, small 10-14.9 cm) in the Saihanba Nature Reserve. Based on the tree ring width index (RWI), we analyzed the correlation between radial growth and climatic factors and their ecological resilience to drought events. The results showed that the RWI of 30-year-old small-diameter trees was significantly positively correlated with standardized precipitation evapotranspiration index (SPEI) from September to December of the previous year and February of the current year. RWI of 30-year-old large-diameter and medium-diameter trees was correlated with SPEI from September of the previous year to June of the current year, but the correlation was statistically non-significant. The RWI of 40-year-old large-diameter trees was significantly negatively correlated with the maximum mean temperature in October of the previous year and June of the current year, as well as the mean temperature in June of the current year. The RWI of 40-year-old medium-diameter trees was significantly negatively correlated with the maximum mean temperature and mean temperature in October of the previous year and significantly positively correlated with SPEI in July of the current year. The RWI of 40-year-old small-diameter trees was significantly positively correlated with SPEI from September of the previous year to June of the current year. The resistance of radial growth of trees with different ages to four drought events (40 years old significantly higher than 30 years old) and the resilience exhibited a significant downward trend, while the recovery showed a significant upward trend (40 years old significantly lower than 30 years old). Within the same age group, the responses of P. sylvestris var. mongolica with different diameter classes to drought events were different. The resistance and resilience of large and medium diameter classes of 40-year-old trees were significantly higher than those of small diameter class trees, but their recovery showed no significant difference. For 30-year-old trees, there were no significant differences in resistance, recovery, or resilience among different diameter classes. P. sylvestris var. mongolica of different ages and diameter classes experienced varying degrees of drought stress, resulting in a significant decrease in resilience. The 40-year-old trees exhibited high resistance, while the 30-year-old trees showed high recovery capability. Small diameter class trees were most severely affected by drought stress.

Trees being removed in fuel reduction treatments are often smaller in diameter than those historically removed in a timber harvest. There are many opportunities to use this material but the resource characteristics must match the final product and the manufacturing method at the appropriate scale of the local community. Research has shown this material is suited for a number of products ranging from structural lumber (small diameter trees coming from suppressed stands appear to have properties similar to old growth), to cut-stock (clear cuttings), to roundwood products (posts and poles). Using emerging technology to capture as much value from this resource as possible is key in offsetting treatment costs. Challenges associated with these treatments include peoples’ conflicting expectations for forested landscapes, the economics of harvesting and hauling this material using the existing infrastructure, and the tradeoffs of performing these activities where they are most needed.

Does hollow occurrence vary with forest type? A case study in wet and dry Eucalyptus obliqua forest

Renewable and sustainable composite materials can be produced using forest biomass if we maintain healthy forests. Small diameter trees and other forest biomass can be processed in the forest into small solid wood pieces, sliced veneers, strands, flakes, chips, particles and fiber that can be used to make construction composite products such as gluedlaminated lumber, plywood, structural composite lumber, flakeboard, particleboard, fiberboard, and molded materials. It can also be combined with other resources to make new materials taking advantage of the unique properties of each resource. Non-construction composites can also be made such as geotextiles, filters, sorbents, packaging and nano-materials. The adhesive used in the various products depends on the intended application.

Colorado's forests are at risk to forest health problems and catastrophic fire. Forest areas at high risk to catastrophic fire, commonly referred to as Red Zones, contain 2.4 million acres in the Colorado Front Range and 6.3 million acres Statewide. The increasing frequency, size, and intensity of recent forest fires have prompted large appropriations of Federal funds to reduce fire risk and improve fire protection. Experimental ecological restoration studies using thinning and prescribed fire have been conducted at several locations across the State during the past 5 years to determine if high-risk areas could be treated to improve forest health and reduce the potential for catastrophic fires. These studies established that 80 to 96 percent of the trees removed to improve ecological conditions were between 5 and 11.9 inches in diameter. Some trees 12 inches and larger in diameter had to be removed to properly apply ecological prescriptions and typically comprised 4 to 18 percent of the trees removed. The projects studied had profit margins of 1 percent (Pines Partnership), 6 percent (Mixed Conifer Project), a loss of $78,000 (Chessman Reservoir-Trumbull Project), and required subsidies of $779 per acre (Fox Run) and $679 per acre (Air Force Academy).

Sycamore (Acer pseudoplatanus L.) is a tree species with highly valuable wood. Similar to European beech (Fagus sylvatica L.), the stemwood of sycamore can be devalued due to the discolouration i.e. brown heart (hearwood discolouration, hereafter). This paper aims to establish the influence of tree traits and site characteristics on the formation of heartwood discolouration and the possibility of predicting the occurrence of heartwood discolouration. For this purpose, 351 sycamore trees from 38 sites in Slovenia, most of them on carbonate bedrock and in the mountain vegetation belt, were analysed. Stem analysis was carried out on all the trees and the age, diameter at breast height (dbh), height of crown base, forking and crown size, were established. On the stump and upper fronts of the first and second logs, the maximum heartwood discolouration diameter was measured. Using logistic regression, the positive influence of age, relative crown length and average diameter increment on the formation of heartwood discolouration was ascertained. Conversely, the probability of heartwood discolouration was diminished by diameter increment in the last 20 years. In the less productive sites, the probability of formation of heartwood discolouration was relatively high in small diameter trees, but it increased slowly with diameter. Tree forking also contributed to a large extent of the heartwood discolouration. After the diameter at breast height achieves 45 cm, the formation of heartwood discolouration on the first log is highly probable. As in beech, the heartwood discolouration increases along the stem axis up to a height of 6–8 m, and decreases in the higher parts of the tree.

Successfully reintroducing rare plant populations to recover historical community composition may require multiple efforts and greater lengths of time than is typically devoted by researchers. To improve the probability of successful colonization and to learn about the life history of the regionally endangered mahogany mistletoe (Phoradendron rubrum) in the Florida Keys, United States, we conducted sequential augmentations for 10 years across two host tree sizes, two seed sources, and six recipient sites. Long‐term monitoring for 13 years revealed that sowing fresh seeds in dry periods from introduced versus wild plants onto small diameter trees (&lt;20 cm diameter at breast height [dbh]) that had branch diameters 15–20 mm resulted in the greatest colonization success. An average of 38.7% of seeds germinated and 23.8% survived to 2015. Plant development was quite slow. Seeds required over 100 days to germinate, 1.6 years for cotyledon emergence, and over 4.7 years to produce fruit. We detected first recruitment nearly 8 years after installation. Population growth improved following multiple attempts and expanded spatial extent as is predicted by theory. Portions of the life cycle are undetectable and thus could give false indications of reintroduction success or failure. Achieving and documenting unequivocal success of this reintroduction has required over a decade.

When a log is sawn along the length, an outward bending or deflection of two half rounds arises from the release of growth stresses in the log. The relationship between this outward bending and the peripheral longitudinal growth strain in logs from a 10-year-old Eucalyptus nitens plantation was investigated. In total, 63 trees were felled and two logs (one bottom and an upper log) were cut from each felled tree. A strong association was observed between the measured longitudinal growth strain and the outward bending produced by splitting the log along its axis. A mathematical model was developed that enables calculation of the relationship between the surface axial growth stress and the opening of the split log. This involves calculation of the lateral deflection of a tapered cantilever beam of semi-circular cross-section under a known bending moment. The relationship between the opening of the slit log and the surface axial stress showed good agreement with the measured data on 126 logs. The model equation is effective in predicting the growth stress from the magnitude of the log distortion. This log sawing or splitting method is quick and reliable for assessing the surface growth stresses in small diameter trees. It could have potential in breeding programs for identifying families or clones for low-growth stresses of superior eucalypts for sawn timber production.

Energy production from wood-based biomass is recognized as a sustainable energy source under current EU regulations. This approach could significantly contribute to Sweden’s energy strategy, given the country’s vast forestlands, which cover 27.9 million ha. This study explores factors influencing the occurrence of biomass-dense forests’ – stem-dense forests with small diameter trees (BDFs) – across Sweden, considering large-scale variables, site characteristics, and management settings. Using Swedish National Forest Inventory data, we found that stand age and site productivity were the strongest predictors of BDF occurrence nationally and regionally, with older, low-productivity stands accumulating high biomass due to prolonged periods without thinning. BDFs were most common in northern regions (Northern and Southern Norrland) where long rotation cycles and seasonal thinning constrains, and high-elevation sites favored BDFs formation. Additionally, soil conditions played a critical role, with BDFs more frequent on wet, and peat soils, which are less productive and are less frequently thinned. Our results also demonstrated high complexity of site conditions and their interactive effects on the occurrence of BDFs. Nevertheless, we suggest that stand age, site productivity, tree species composition, and soil moisture can guide biomass management decisions, including thinning practices, in the context of increasing demand for renewable energy.