Forest Science

García, Oscar

doi: 10.1093/forsci/fxab043pmid: N/A

Models at various levels of resolution are commonly used for both forest management and ecological research. They all have comparative advantages and disadvantages, making desirable a better understanding of the relationships between various approaches. Accounting for crown and root morphological plasticity in the limit where equilibrium among neighbors is reached (perfect plasticity) transforms spatial models into nonspatial, distance-independent versions. The links between spatial and nonspatial models obtained through a perfect plasticity assumption are more realistic than ignoring spatial structure by a mean field approximation. This article also reviews the connection between distance-independent models and size distributions and how distributions evolve over time and relate to whole-stand descriptions. In addition, some ways in which stand-level knowledge feeds back into detailed individual-tree formulations are demonstrated. This presentation is intended to be accessible to nonspecialists.

Yang, Sheng-I; Cao, Quang V; Shoch, David T; Johnson, Trisha

doi: 10.1093/forsci/fxab051pmid: N/A

Accurately assessing forest structure and productivity is critical to making timely management decisions and monitoring plant communities. This study aims to evaluate the prediction accuracy of site-level stand and biomass tables from the diameter distribution models. The efficacy of the single Weibull function and two finite mixture models was compared for six species groups on three mixed-hardwood sites in eastern Tennessee, USA. To evaluate model performance, two types of stand/biomass tables were generated. The first type was constructed from all species on a given site (site-specific), whereas the second type was built for a single species from all sites (species-specific).Results indicate that both types of stand and biomass tables were consistently well quantified by the two-component mixture model in terms of goodness of fit, parsimony, and robustness. The two-component mixture model better characterized the complex, multimodal diameter distributions than the single Weibull model, which underpredicted the upper portion of the distributions. The three-component model tends to overfit the data, which results in lower prediction accuracy. Among the three models examined, the two-Weibull mixture model is suggested to construct site-level stand/biomass tables, which provides more reliable and accurate predictions to assess forest structure and product class.

Ajala, Olaniyi O; Kidd, Kathryn R; Oswald, Brian P; Weng, Yuhui; Stovall, Jeremy P

doi: 10.1093/forsci/fxab046pmid: N/A

A greenhouse experiment was designed to determine the interactive effect of light, flooding, and competition on the growth and performance of Chinese tallow (Triadica sebifera [L.] Roxb.) and three tree species native to the southeastern United States: water tupelo (Nyssa aquatica L.), sugarberry (Celtis occidentalis L.), and green ash (Fraxinus pennsylvanica Marshall). The experiment used a factorial design that received two treatments: light (low irradiance or high irradiance) and flood (nonflooded and flooded) regimes. In the nonflooded and high irradiance treatment, changes in the growth (ground diameter, number of leaves, and total biomass) indicated that growth metrics of tallow were highest when growing with sugarberry and water tupelo but decreased when tallow was in competition with green ash. In contrast, competition with tallow reduced the height, net photosynthetic rate, stomatal conductance, and transpiration rate of water tupelo. The results showed that tallow had lower growth metrics when in competition with green ash at no apparent decrease in the growth of green ash except for growth rate. Our results suggest that tallow may be less competitive with certain native species and underplanting may be a possible opportunity for improving the success rates of native tree species establishment in areas prone to tallow invasion.

Zheng, Yaxiong; Fan, Shaohui; Guan, Fengying; Xia, Wen; Wang, Shumei; Xiao, Xiao

doi: 10.1093/forsci/fxab044pmid: N/A

Strip clearcutting of Moso bamboo forests in southern China has seen increasing interest as a way of reducing harvesting costs. Previous research has shown that cutting influences the overstory structure and drives changes in the microclimate and soil properties. However, the effects of strip cutting on understory vegetation diversity and composition remain unclear. To better understand the influence of cutting on the understory vegetation, this study compares sites under natural restoration after cut and uncut sites in the Moso bamboo forest. We selected plots that were cut in 2019 (C19) and 2017 (C17), as well as unharvested plots as controls (CK). The results showed that strip clearcutting increased the understory vegetation richness and diversity, and a significant difference (A = 0.23, P = 0.001) existed in the composition of the vegetation between the three treatments. Furthermore, the decrease of soil total phosphorus and total potassium content resulted in the difference in undergrowth vegetation distribution and composition between the uncut plots and the cut plots. Our results suggest that strip clearcutting may not be harmful to biodiversity on a local scale in the Moso bamboo forest.

Walker, Trevor D; Cumbie, W Patrick; Isik, Fikret

doi: 10.1093/forsci/fxab054pmid: N/A

The use of genomic markers in forest tree breeding is expected to improve the response to selection, especially within family. To evaluate the potential improvements from genotyping, we analyzed a large Pinus taeda L. clonal population (1,831 cloned individuals) tested in multiple environments. Of the total, 723 clones from five full-sib families were genotyped using 10,337 single-nucleotide polymorphism markers. Single-step models with genomic and pedigree-based relationships produced similar heritability estimates. Breeding value predictions were greatly improved with inclusion of genomic relationships, even when clonal replication was abundant. The improvement was limited to genotyped individuals and attributable to accounting for the Mendelian sampling effect. Reducing clonal replication by omitting data indicated that genotyping improved breeding values similar to clonal replication. Genomic selection predictive ability (masking phenotypes) was greater for stem straightness (0.68) than for growth traits (0.41 to 0.44). Predictive ability for a new full-sibling family was poorer than when full-sibling relationships were present between model training and validation sets. Species that are difficult to propagate clonally can use genotyping to improve within-family selection. Clonal testing combined with genotyping can produce breeding value accuracies adequate to graft selections directly into deployment orchards without progeny testing.

Conrad, Joseph L

doi: 10.1093/forsci/fxab052pmid: N/A

Georgia and other southern states have far lower gross vehicle weight (GVW) limits for log trucks than other US regions and other countries. Low GVW limits result in high hauling costs and truck traffic. In 2020, including tolerances, five-axle log tractor-trailers were allowed 38,102 kg (84,000 lb) GVW in Georgia. Telephone surveys of 30 loggers and 32 forest industry representatives from the state of Georgia were conducted to measure perceptions of weight regulations and assess support for alternative weights and configurations. The four alternatives included five axles, 39,916 kg (88,000 lb); six axles, 41,277 kg (91,000 lb); six axles, 45,359 kg (100,000 lb); and seven axles, 45,359 kg (100,000 lb) GVW. The majority of loggers and forest industry representatives stated that GVW limits for log trucks were too low. The average preferred GVW limits were 39,621 kg (87,350 lb) and 40,545 kg (89,387 lb) for loggers and forest industry, respectively. Loggers and forest industry supported the five-axle 39,916 kg (88,000 lb) configuration whereas many loggers opposed both 45,359 kg (100,000 lb) configurations. Loggers, forest industry, and policymakers should work to modernize weight laws to reduce hauling costs, maintain or improve safety, and protect public infrastructure.

Hawks, Brent S; Bolding, M Chad; Aust, W Michael; Barrett, Scott M; Schilling, Erik; Horton, Celeste N

doi: 10.1093/forsci/fxab057pmid: N/A

Forestry best management practices (BMPs) were created in response to the Clean Water Act of 1972 to protect water quality from nonpoint source pollutants such as sediment. The objectives of this study were to quantify the relationship between BMP implementation and sediment delivery on 58 recently harvested sites across three physiographic regions and five forest operational features. BMP implementation rates, erosion rates, sediment delivery ratios, and sediment masses were calculated at 183 silt fences functioning as sediment traps adjacent to streams in Virginia and North Carolina. Major access system features, including stream crossings, skid trails, and haul roads, typically delivered the greatest sediment mass to streams and had the highest sediment delivery ratios on a per feature basis. When accounting for sediment mass delivered and area in each feature, harvest area accounted for approximately 70% of sediment delivered to streams for all regions. Most features had proportionally higher erosion rates than sediment masses collected at silt fences, indicating that most erosion generated by forest operations is being trapped by either harvest areas or streamside management zones. For most features and regions, as BMP implementation increased, erosion rates and the sediment masses delivered to streams decreased.

Weyrens, Josh; Germain, Rene

doi: 10.1093/forsci/fxab055pmid: N/A

Beech bark disease is a pathogenic complex that has been spreading throughout the American beech’s range since the 1800s. A litany of negative consequences have manifested from the infestation of this disease, many of which deteriorate the ecological functions of forestland. This case study sought to analyze the cost structure for removing a recalcitrant beech understory via mechanized shelterwood harvesting. High-resolution data regarding the day-to-day operation of harvesting equipment was collected using daily production journals. Interviews were conducted with the logging company owner and maintenance supervisor to gather additional information required to calculate machine costs, overhead, job specific costs, and trucking costs. The yield from this harvest was 527 metric tonnes of sawtimber and 4,893 tonnes of clean chips. The total harvesting cost equated to $4,651/ha, with the cost attributed to removing beech at $204/ha. Despite the additional cost of beech removal, the logger generated a total profit of $5,965 and a return on investment of 7.5%, allowing us to conclude that mechanized harvesting can be a viable beech removal strategy given the forest stocking and market conditions that are in place.

Meeks, Abigail; Poudyal, Neelam C; Muller, Lisa I; Yoest, Chuck

doi: 10.1093/forsci/fxab049pmid: N/A

Deer hunting is a major forest-based recreation activity in the US South. However, the recent discovery of chronic wasting disease (CWD) threatens deer hunting in the region. Stakeholders are interested in understanding how hunters perceive the risk and change their hunting behavior. This study found a significant change in hunters’ concerns after the first deer season since the discovery of CWD in Tennessee, USA. Results also showed that hunters’ short- and long-term intentions to hunt deer in the region were positively related to previous experience of hunting in CWD-affected areas, beliefs in the effectiveness of herd reduction to control CWD, concerns regarding potential decline in deer quality and changes in hunting regulations due to CWD, and trust in wildlife agency action. Hunters who hunt on public land and were concerned with deer and human health risk were less likely to hunt in the CWD region. These results are useful in understanding hunter behavior in response to wildlife disease and identifying variables that may help project immediate as well as long-term change in hunting demand in affected regions.

Higuita-Aguirre, María Isabel; Osorio-Vega, Walter; León-Peláez, Juan D

doi: 10.1093/forsci/fxab050pmid: N/A

Poor seedling quality is a major limiting factor for the success of commercial afforestation and ecological restoration in the tropics. This is commonly due to poor nutrient availability of soil-based substrates used for seedling growth. Currently, the use of biofertilizers has gained attention as a biotechnological tool to overcome plant malnutrition and enhance seedling quality from the nursery. The aim of this study was to evaluate the effects of individual and combined inoculation with selected beneficial soil microorganisms on plant growth of Tabebuia rosea (Bertol.) Bertero ex A.DC. in the nursery stage. For this purpose, individual, dual, and triple inoculations were conducted with Rhizoglomus fasciculatum (arbuscular mycorrhizal fungus: AMF), Mortierella sp. (mineral-solubilizing fungus: MSF), and Azospirillum brasilense (plant growth-promoting bacteria: PGPB). After six months, the inoculation with PGPB significantly promoted plant growth over the uninoculated control. Dual inoculation with AMF+MSF and AMF+PGPB had lower but significant effects over the control. The results showed that biofertilization is an effective alternative to promote plant growth and quality of this species in the nursery and thus to produce better plants for forestry and ecological restoration in tropical areas.