Opportunities and Challenges of Utilizing Small Diameter Timber from Fuel Reduction Thinning Programs

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.

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.

Longer-term impacts of fuel reduction treatments on forest structure, fuels, and drought resistance in the Lake Tahoe Basin

Forest fires and extreme droughts will continue to be main disturbances in Mediterranean ecosystems, given the ongoing and projected climatic changes. In fact, an exacerbation of some aspects of their regime is expected. In this perspective, it is fundamental to design adaptive management strategies that can reduce the impact of disturbances and increase ecosystem resilience. To achieve this, it is necessary to develop an integrated management, able to select the best combination of restoration actions for different scenarios. Here, we address the effectiveness of the combination of several actions related to fuel reduction and restoration after fire in the long term, to increase the presence of resprouting species and mitigate fire occurrence, for different future climate change scenarios. Fuel reduction treatments include the application of shrub clearing at different intensities and frequencies. Restoration actions comprise the plantation of resprouting species, aiming to increase ecosystem resilience. We used a simple, ecological, published model, specifically developed for Mediterranean ecosystems and including species competition and post-fire responses, which we calibrated using the recorded vegetation response to treatments. Our results point out that, if we look for more resilient ecosystems in the next decades, we will need an intensification of fuel reduction treatments. Noticeably, including resprouting species has an important effect in the ecosystem. However, the success of these actions will be variable depending on the climate scenario.

Wildfire activity in the western U.S. has highlighted the importance of effective management to address this growing threat. The Lookout Mountain Thinning and Fuels Reduction Study (LMS) is an operational-scale, long-term study of the effects of forest restoration and fuel reduction treatments in ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and mixed-conifer forests in central Oregon, U.S. The broad objectives of the LMS are to examine the effectiveness and longevity of treatments on wildfire risk and to assess the collateral effects. Treatments include four levels of overstory thinning followed by mastication of the understory vegetation and prescribed burning. Stands were thinned to residual densities of 50, 75, or 100% of the upper management zone (UMZ), which accounts for site differences as reflected by stand density relationships for specific plant communities. A fourth treatment combines the 75 UMZ with small gaps (~0.1 ha) to facilitate regeneration (75 UMZ + Gaps). A fifth treatment comprises an untreated control (UC). We examined the causes and levels of tree mortality that occurred 2–9 years after treatments. A total of 391,292 trees was inventoried, of which 2.3% (9084) died. Higher levels of tree mortality (all causes) occurred on the UC (7.1 ± 1.9%, mean ± SEM) than on the 50 UMZ (0.7 ± 0.1%). Mortality was attributed to several bark beetle species (Coleoptera: Curculionidae) (4002 trees), unknown factors (2682 trees), wind (1958 trees), suppression (327 trees), snow breakage (61 trees), prescribed fire (19 trees), western gall rust (15 trees), cankers (8 trees), mechanical damage (5 trees), dwarf mistletoe (4 trees), and woodborers (3 trees). Among bark beetles, tree mortality was attributed to western pine beetle (Dendroctonus brevicomis LeConte) (1631 trees), fir engraver (Scolytus ventralis LeConte) (1580 trees), mountain pine beetle (Dendroctonus ponderosae Hopkins) (526 trees), engraver beetles (Ips spp.) (169 trees), hemlock engraver (Scolytus tsugae (Swaine)) (77 trees), and Pityogenes spp. (19 trees). Higher levels of bark beetle-caused tree mortality occurred on the UC (2.9 ± 0.7%) than on the 50 UMZ (0.3 ± 0.1%) which, in general, was the relationship observed for individual bark beetle species. Higher levels of tree mortality were attributed to wind on the 100 UMZ (1.0 ± 0.2%) and UC (1.2 ± 1.5%) than on the 50 UMZ (0.2 ± 0.02%) and 75 UMZ (0.4 ± 0.1%). Higher levels of tree mortality were attributed to suppression on the UC (0.5 ± 0.3%) than on the 50 UMZ (0.003 ± 0.002%) and 75 UMZ + Gaps (0.0 ± 0.0%). Significant positive correlations were observed between measures of stand density and levels of tree mortality for most causal agents. Tree size (diameter at 1.37 m) frequently had a significant effect on tree mortality, but relationships varied by causal agent. The forest restoration and fuels reduction treatments implemented on the LMS increased resistance to multiple disturbances. The implications of these and other results to the management of fire-adapted forests are discussed.

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.

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

Understory plant community responses to hazardous fuels reduction treatments in pinyon-juniper woodlands of Arizona, USA

The study examined the extraction and consumption pattern of small timber and its socioeconomic and forest resource determinants among the rural people in district Ganderbal of Kashmir. The results showed that the total extraction of small timber from different sources in the sample villages was 39.46 tons annum-1, which is mostly consumed in housing and roofing (39.63%) followed by cattle shed/ store house (15.25%), rural furniture/ packing cases (14.75%), agricultural implements (13.25%), fencing (12.50%) and others (4.62%). The total small timber demand was 47.88 m3 annum-1, which is mostly procured from agroforestry (42.57%) followed by forests (26.09%), homestead forestry (17.05%) and social/ community forestry (14.29%). The people were destitute with respect to socioeconomic attributes while they are well-off regarding forest resource characteristics. Correlation and multiple regression analysis established a robust relationship between small timber consumption and socioeconomic and forest resource parameters. The small timber flow from forests to the sample villages is excessive as compared to the national estimates, creating threats to the biodiversity conservation and ecological stability of the adjoining forests. The over-utilization of forest biomass by the local people is leading to degradation of forest resources and diminished biomass productivity, which in turn induce socioeconomic and livelihood stress. Therefore, some alternative interventions are essential to be implemented efficiently to keep pace with current development and future challenges.

Connect Four is a two player table. Players alternate dropping checkers into a 6 X 7 vertical grid. The first player to have four of their respective pieces on a horizontal, vertical, or diagonal row wins the game. In this paper, we consider playing connect four on trees. We are able to classify all trees on which the first player can win in their first four moves. We also give a construction of an infinite family of trees on which the first player can win. In addition, we consider trees of small diameter and trees in which the maximum degree is large.

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).

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.

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 (<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.