Search Results (57)

This study scientifically assessed the safety of the Ming Dynasty official-style timber structure of Taiyuan Chongshan Temple’s Great Mercy Hall, a nationally protected cultural relic. An integrated framework was adopted, including form restoration via 3D laser scanning and manual surveying, damage detection using impedance meters, stress wave tomography and one-dimensional stress wave testing, mechanical analysis with a differentiated material finite element model, and short-term on-site monitoring at risk points. Results showed that the 303.3 mm construction ruler length was restored, with the column grid tilting northwestward; the main structure was hardwood pine, and critical columns had severe localized damage (24% internal damage rate, 13% cross-sectional damage ratio) with 42% residual strength in some members; and the structure remained elastically safe, with material degradation causing 6.3–13.3% linear displacement amplification. Two weak links (eave purlin deflection: 33–37 mm; double-eave golden column axial force concentration: 86.9–88.5 kN) and dougong’s outward inclination due to eccentric compression were identified. Short-term monitoring indicated temperature-driven elastic responses and an 8 mm cumulative residual displacement in the northern single-step beam, and a three-level early warning threshold system was proposed. This study clarified the hall’s state as “overall stable with localized weaknesses”, providing a methodological reference for the preventive protection of similar ancient timber structures. Full article

Many native mammal species rely on the habitat elements provided by old-growth forests in the eastern United States (U.S.). Today, old-growth forests persist as remnant stands in the landscape. Historically, they included a mosaic of eastern forest types including mixed mesophytic, oak–hickory, southeastern evergreen, and hemlock-white pine-northern hardwood forests. Due to the rapid (<250 years) and almost complete (99% loss) removal of old-growth forests from eastern U.S. landscapes, research regarding the current and historic relationship between native mammals and old-growth forests is lacking. Using comparisons with better-studied old-growth forests in the western U.S., historical accounts of mammal distribution, and the habitat elements of eastern old-growth forest types, we aim to describe the mammals currently and historically supported by these rare forests in this scoping review. Full article

Assessing decay-induced mechanical deterioration in hardwood components is essential for the conservation of northern Chinese timber heritage, where structural members such as the Dou and Gong have been exposed to complex environments for centuries. Within a unified experimental framework, this study systematically investigated the mechanical degradation behavior of two hardwood species commonly used in traditional timber buildings in northern China—elm (Ulmus pumila L.) and Chinese scholar tree (Styphnolobium japonicum (L.) Schott)—subjected to controlled brown-rot fungal decay (Gloeophyllum trabeum) over decay durations of 0–6 months. Four mechanical loading configurations were considered: tension, bending, compression parallel to grain and compression perpendicular to grain. Decay progression was quantitatively characterized using mass loss rate (MLR), ultrasonic elastic modulus loss rate (ELR) and strength loss ratio (SLR). The two hardwoods exhibited distinct material- and loading-dependent deterioration patterns. Elm showed faster and more variable degradation, with clearer time-dependent strength loss under tension and bending, whereas Chinese scholar tree displayed slower and more scattered strength deterioration. For both species, elastic modulus reduction generally preceded measurable mass loss, indicating that modulus-based indicators are more sensitive to decay progression under the tested conditions. Correlation analyses further indicate that ELR tends to show more stable and consistent associations with strength loss than MLR across most loading modes. Overall, the results suggest that elastic modulus–based ultrasonic indicators have potential advantages for characterizing mechanical deterioration under controlled decay conditions. However, the findings are limited to the tested materials, decay scenarios and loading configurations, and further validation on aged or naturally decayed components is required before in situ application to heritage structures can be established. Full article

There is a widespread belief that koala conservation measures should be focused on ending forestry operations in native forests and that plantations should be the alternative source for timber. While advocates for conservation continue to promote this strategic approach, they overlook the fact that hardwood plantations also provide important habitats. Ongoing operations in both natural and planted forests continue to threaten the viability of the koala species, and populations in one of the koala’s core habitats in northern New South Wales (NSW) continue to decline. To improve conservation outcomes for this species in the wild, the Great Koala National Park (GKNP) has been proposed. While the process of establishing this park continues, ongoing forestry operations exert continuous pressure on koalas and their habitat within the proposed area of the park. This paper investigates how community stakeholders are collaborating with scientists to identify areas of high koala habitat value within the hardwood eucalypt plantations inside the proposed GKNP that are currently excluded from conservation and will be subject to ongoing timber extraction. Investigations of Tuckers Nob State Forest, which is inside the proposal area, confirmed the presence of both koalas and original forest inside the plantations which were excluded from conservation by the state government. Original trees and remnants were identified using historical aerial photography, which were orthorectified and matched against current NSW government imagery (SIX Maps); composite mosaics of photographic sheets and closeups (Quantum GIS) were imported into Google Earth Pro. Koala drone surveys, habitat ground-truthing, and on-ground scat and koala surveys of 120 ha involving various community stakeholders were conducted in December 2024 and revealed 25 koalas records, necessitating the reclassification of this area from plantation to prime koala habitat. Here, as in many other plantations in NSW, the findings of this study indicate significant numbers of original trees that are part of highly diverse nutrient-rich sites attractive to koalas. This leads to the conclusion that the exclusion of specific areas of the proposed park from conservation to allow for ongoing logging is inconsistent with recognized koala protection strategies. Hence, koala protection strategies need to consider the integrity of the reserve system in its entirety, and the whole area of the GKNP should be accorded the requisite status of a World Heritage Site. Full article

Northern hardwood forests of the Lake Superior region face a series of novel disturbance pressures including canopy dieback. Previous studies have linked regional sugar-maple (Acer saccharum) canopy dieback to introduced earthworms, which may have coinciding impacts on the ground-layer plant community. Dieback–earthworm interactions may lead to important longer-term changes in forest structure and function, but these relationships but have not been characterized. We sampled ground-layer plant communities in five national forest units in Michigan, Wisconsin, and Minnesota in 2010, and again just over a decade later in 2021. Non-metric multidimensional scaling ordination and indicator species analysis were used to assess relationships among ground-layer community composition and structure, functional traits, and environmental gradients including forest-floor condition and A. saccharum canopy dieback. Increases in dieback and earthworm disturbance in the decade between inventories were accompanied by a marked divergence in observed ground-layer plant community structure between national forests. Ordinations of 2021 data indicated a strengthening relationship between forest-floor condition and earthworm abundance. Our results suggest that earthworm impacts and A. saccharum dieback are driving changes in the ground layer on broad geographic and temporal scales, with short- and long-term implications for plant-community structure and function, and higher trophic levels. Full article

In many hardwood forests, resprouting is a common response to disturbance and basal resprouts may represent a substantial component of the forest understory, especially post-wildfire. Despite this, resprouts are often overlooked in biomass assessments and drivers of resprouting responses in certain species are still unknown. These knowledge gaps are problematic as the contribution of resprouts to understory fuel loads are needed for wildfire risk modeling and effective forest stewardship. Here, we validated the handheld mobile laser scanning (HMLS) of basal resprout volume and field measurements of stem count and clump height as methods to estimate the mass of California Bay Laurel (Umbellularia californica) basal resprouts at Pepperwood and Saddle Mountain Preserves, Sonoma County, California. In addition, we examined the role of tree size and wildfire severity in predicting post-wildfire resprouting response. Both field measurements (clump height and stem count) and remote sensing (HMLS-derived volume) effectively estimated dry mass (total, leaf and wood) of U. californica resprouts, but underestimated dry mass for a large resprout. Tree size was a significant factor determining post-wildfire resprouting response at Pepperwood Preserve, while wildfire severity significantly predicted post-wildfire resprout size at Saddle Mountain. These site differences in post-wildfire basal resprouting predictors may be related to the interactions between fire severity, tree size, tree crown topkill, and carbohydrate mobilization and point to the need for additional demographic and physiological research. Monitoring post-wildfire changes in U. californica will deepen our understanding of resprouting dynamics and help provide insights for effective forest stewardship and wildfire risk assessment in fire-prone northern California forests. Full article

In forests dominated by deciduous tree species, coniferous species are often disproportionately important because of their contrasting functional traits. Eastern white pine (Pinus strobus L.), once a widespread emergent canopy species, co-occurs with deciduous hardwoods in the northern Lake States, but is often uncommon in contemporary hardwood stands. To gain insights into the potential utility of hardwood management strategies for simultaneously regenerating white pine, we leveraged a northern hardwood silvicultural experiment with scattered overstory pine. Seven growing seasons post-harvest, we conducted a complete census of white pine regeneration (height ≥ 30 cm) and mapped their locations and the locations of potential seed trees. Pine regeneration was sparse and strongly spatially aggregated, with most clusters falling within potential seed shadows of overstory pines. New recruits were found to have the highest density in a scarified portion of the study area leeward of potential seed trees. Low regeneration densities within treatment units, strong spatial aggregation, and the spatial arrangement of potential seed trees precluded generalizable inferences regarding the utility of specific treatment combinations. Nevertheless, our results underscore the critical importance of residual overstory pines as seed sources and highlight the challenges associated with realizing their potential in managed northern hardwoods. Full article

Salt-affected soil areas are increasing in the Northern Great Plains (NGP), with patches occurring in some of the most productive croplands. High electrical conductivity (EC) and sodium and/or sulfate concentrations of saline–sodic areas impede the growth and yield of ‘normal’ [corn (Zea mays)/soybean (Glycine max)] rotational crops, and more appropriate management systems are needed. Brassica spp. and amendment applications, such as biochar, may provide management alternatives for these areas. In two greenhouse studies, (1) 10 canola (Brassica napus) genotypes were evaluated for emergence in non-saline (EC_1:1 = 0.62 dS m⁻¹), moderately saline–sodic (EC = 5.17 dS m⁻¹), and highly saline–sodic (EC_1:1 = 8.47 dS m⁻¹) soils and (2) 10 canola genotypes and 3 other brassicas (Brassica juncea/B. oleracea) were evaluated for emergence and biomass in non-saline or moderately saline–sodic soils with or without two 5% biochar (hardwood or softwood) amendments. Canola emergence at 28 days after planting (DAP) in moderately and highly saline–sodic soils was less than 12% for most genotypes, although one had 37% emergence. The hardwood biochar improved Brassica spp. emergence (42%) from the moderately saline–sodic soil compared to non-amended soil (29%), although shoot biomass was similar among treatments at 60 DAP. These findings suggest that specific salt-tolerant Brassica spp. may be an alternative crop for NGP saline–sodic soil areas. Florida broadleaf mustard, typically used for forage, had the greatest emergence (52%) in the saline–sodic soil and may be a suitable cover crop for these areas. In addition, hardwood biochar applications may aid in plant establishment. Full article

The relative influence of climate and Indigenous cultural burning on past forest composition in southern New England, US, remains debated. Employing varied analyses, this study compared data on Indigenous settlements from over 5000 years before present (YBP) with relative tree abundances estimated from pollen and land survey records. Results suggested that fire-tolerant vegetation, mainly oak (Quercus spp.), was more abundant near Indigenous settlements from 4955 to 205 YBP (i.e., 86–91% fire-tolerant trees), and significantly (p < 0.05) higher from 3205 to 205 YBP; fire-tolerant vegetation was less abundant away from settlements, where it also experienced greater fluctuations. Correlative models showed that warmer temperatures and distance to Indigenous settlement, which are both indicators of fire, were important predictors in the 17th–18th centuries of fire-tolerant tree abundance; soil variables were less important and their relationships with vegetation were unclear. A marked increase in oak abundance occurred above 8 °C mean annual temperature and within 16 km of major Indigenous settlements. Pyrophilic vegetation was most correlated with distance to Indigenous villages in areas with 7–9 °C mean annual temperature, typical of higher latitudes and elevations that usually supported northern hardwoods. Widespread burning in warmer areas potentially weakened relationships between distance and pyrophilic abundance. Indigenous land use imprinted upon warmer areas conducive to burning created patterns in fire-tolerant vegetation in southern New England, plausibly affecting most low-elevation areas. Results imply that restoration of fire-dependent species and of barrens, savannas, and woodlands of oak in southern New England benefit from cultural burning. Full article

In northern hardwood forests, litter decomposition might be affected by nutrient availability, species composition, stand age, or access by decomposers. We investigated these factors at the Bartlett Experimental Forest in New Hampshire. Leaf litter of early and late successional species was collected from four stands that had full factorial nitrogen and phosphorus additions to the soil and were deployed in bags of two mesh sizes (63 µm and 2 mm) in two young and two mature stands. Litter bags were collected three times over the next 2 years, and mass loss was described as an exponential function of time represented by a thermal sum. Litter from young stands had higher initial N and P concentrations and decomposed more quickly than litter from mature stands (p = 0.005), regardless of where it was deployed. Litter decomposed more quickly in fine mesh bags that excluded mesofauna (p < 0.001), which might be explained by the greater rigidity of the large mesh material making poor contact with the soil. Neither nutrient addition (p = 0.94 for N, p = 0.26 for P) nor the age of the stand in which bags were deployed (p = 0.36) had a detectable effect on rates of litter decomposition. Full article

Soil fungal communities are critical for forest ecosystem functions in the Central Hardwood Region (CHR) of the USA. This evaluation, which took place in 2022–2023, investigates the influence of Juglans nigra (BW, black walnut) and Quercus rubra (NRO, Northern red oak) on soil properties and fungal community structures across three CHR sites. The objectives of this study are to investigate how the fungal communities identified beneath J. nigra and Q. rubra serve to influence biodiversity and soil health within hardwood plantations. Soils from two locations in Indiana and one in Michigan were examined and assessed for variations in fungal composition and diversity. Soil fungal communities were characterized using Illumina high-throughput sequencing while multivariate analysis was applied to analyze patterns in these fungal communities. These data provided insights into how environment, location, and tree species affect fungal community structure. Results indicate that J. nigra soils exhibited higher carbon (0.36%, 1.02%, 0.72%), nitrogen (25%, 29%, 56%), and pH (0.46, 1.08, 1.54) levels than Q. rubra soils across all three sites and foster greater fungal diversity. Specifically, J. nigra was associated with increased Ascomycota diversity, whereas Q. rubra supported a higher prevalence of Basidiomycota. Basidiomycota were negatively correlated with carbon and pH, while Ascomycota showed positive correlations with these variables. These findings highlight how crucial it is to understand how different tree species influence fungal communities and, consequently, how they influence forest soil health. Our findings serve to improve forest management practices by emphasizing the importance of fungal communities in maintaining the function and resilience of an ecosystem. Our study underscores that grasping these specific interactions is essential for effective forest management, especially when considering how to use fungal communities to boost plant growth. This work focuses on hardwood plantations rather than either agricultural ecosystems, monocultures, or native forests, thus filling a gap in the current literature where many studies are limited to specific fungal groups such as mycorrhizae. In future research, it is important to examine a wider range of tree species. This will deepen our understanding of fungal community dynamics and their impact on maintaining healthy forest ecosystems. Our hardwood plantation focus also notes the potential for adaptive forest management as environmental conditions change. Full article

Estimation of tree volume typically focuses on excurrent forms, with less attention given to decurrent forms. Species with a decurrent form, particularly hardwoods, lack a dominant stem and have large diameter branches that can be included in the merchantable wood volume. We developed a preliminary two-equation system comprising a taper equation and a merchantable whole-tree volume (stem and branches) equation for Quercus rubra L. growing in Navarra (Northern Spain). The equation system includes the diameter at breast height and total tree height as independent variables, along with merchantable height—the height up to which the stem maintains a well-defined excurrent form—as an additional variable. After estimating the stem volume, the branch volume is estimated by subtracting the stem volume from the merchantable whole-tree volume. A second order continuous autoregressive error structure was used to correct for autocorrelation between residuals from the fitted taper equation. The equations explained 90% of the observed variability in diameter and 86% of the observed variability in merchantable whole-tree volume. Both equations have been implemented in the Cubica Navarra 3.0 software for use as a system of equations. These equations are considered preliminary and will be refitted or validated as additional data becomes available from new locations. Full article

Forests are critical source regions of high-quality drinking water but forest disturbances such as harvesting can alter stream dissolved organic carbon (DOC) concentrations and influence source water treatability. Most stream DOC-centric forest harvesting impact studies report on effects <10 years post-harvest; less is known about the legacy effects of forest harvesting on stream DOC. Here, inter- and intra-catchment variability in stream DOC concentration and export were evaluated in two northern hardwood-dominated headwater catchments (unharvested reference and 24 years post-clearcut). The relationship between stream DOC and the concentration, spatial distribution, and hydrologic connectivity of hillslope solute pool DOC was investigated. Stream DOC concentrations in the legacy clearcut catchment exceeded those in the reference catchment for all flow conditions. Inter-catchment differences in DOC export were inconsistent. Hillslope solute pool DOC concentrations decreased with soil depth but were not significantly different between catchments. Concentration–discharge regression analysis indicated that DOC was primarily transport-limited (flushing) in both catchments. Aqueous potassium silica molar ratio data indicate the influence of groundwater on stream chemistry and streamflow was similar in both catchments. Results suggest that while clearcut harvesting can have detectable decadal-scale effects on stream DOC concentrations in northern hardwood-dominated headwater catchments, the effects are limited and likely do not pose a reasonable threat to downstream drinking water treatment operations. Full article

A precise evaluation of the risk of establishing insect pests is essential for national plant protection organizations. This accuracy is crucial in negotiating international trade agreements for forestry-related commodities, which have the potential to carry pests and lead to unintended introductions in the importing countries. In our study, we employed both mechanistic and correlative niche models to assess and map the global patterns of potential establishment for Aeolesthes sarta under current and future climates. This insect is a significant pest affecting tree species of the genus Populus, Salix, Acer, Malus, Juglans, and other hardwood trees. Notably, it is also categorized as a quarantine pest in countries where it is not currently present. The mechanistic model, CLIMEX, was calibrated using species-specific physiological tolerance thresholds, providing a detailed understanding of the environmental factors influencing the species. In contrast, the correlative model, maximum entropy (MaxEnt), utilized species occurrences and spatial climatic data, offering insights into the species’ distribution based on observed data and environmental conditions. The projected potential distribution from CLIMEX and MaxEnt models aligns well with the currently known distribution of A. sarta. CLIMEX predicts a broader global distribution than MaxEnt, indicating that most central and southern hemispheres are suitable for its distribution, excluding the extreme northern hemisphere, central African countries, and the northern part of Australia. Both models accurately predict the known distribution of A. sarta in the Asian continent, and their projections suggest a slight overall increase in the global distribution range of A. sarta with future changes in climate temperature, majorly concentrating in the central and northern hemispheres. Furthermore, the models anticipate suitable conditions in Europe and North America, where A. sarta currently does not occur but where its preferred host species, Populus alba, is present. The main environmental variables associated with the distribution of A. sarta at a global level were the average annual temperature and precipitation rate. The predictive models developed in this study offer insights into the global risk of A. sarta establishment and can be valuable for monitoring potential pest introductions in different countries. Additionally, policymakers and trade negotiators can utilize these models to make science-based decisions regarding pest management and international trade agreements. Full article

The task of tree species classification through deep learning has been challenging for the forestry community, and the lack of standardized datasets has hindered further progress. Our work presents a solution in the form of a large bark image dataset called CentralBark, which enhances the deep learning-based tree species classification. Additionally, we have laid out an efficient and repeatable data collection protocol to assist future works in an organized manner. The dataset contains images of 25 central hardwood and Appalachian region tree species, with over 19,000 images of varying diameters, light, and moisture conditions. We tested 25 species: elm, oak, American basswood, American beech, American elm, American sycamore, bitternut hickory, black cherry, black locust, black oak, black walnut, eastern cottonwood, hackberry, honey locust, northern red oak, Ohio buckeye, Osage-orange, pignut hickory, sassafras, shagbark hickory silver maple, slippery elm, sugar maple, sweetgum, white ash, white oak, and yellow poplar. Our experiment involved testing three different models to assess the feasibility of species classification using unaltered and uncropped images during the species-classification training process. We achieved an overall accuracy of 83.21% using the EfficientNet-b3 model, which was the best of the three models (EfficientNet-b3, ResNet-50, and MobileNet-V3-small), and an average accuracy of 80.23%. Full article