We report on the 25-year results of a long-term experiment on the Olympic Peninsula, WA comparing a pure Douglas-fir to a mixed Douglas-fir and red alder plantation that was designed to increase the time and space for early-seral habitat. The early-seral stage in Pacific Northwest forests has been greatly diminished driven in part by a reduction in harvests on National Forest land, prioritization of late-seral habitat, and more effective vegetation control. Recent research on early-seral forests highlights the many plant and animal species dependent on this stage and the value of species like red alder in restoring soils, especially those degraded by intense wildfire. In this paper, we evaluate a long-term ecosystem productivity study located on the Olympic Peninsula, WA that seeks to add in early-seral elements to standard rotations by planting red alder and comparing this to a standard Douglas-fir monoculture. Despite some initial implementation challenges that altered the desired species contrast and limited the number of alder planted, we found initial significant alder effects before age 17, including 4.5 × higher stand basal area and 2.9 × higher aboveground biomass. These effects did not persist as the stand developed though. However, significant block differences were observed with deeper, less rocky soils showing more alder effect. Other interspecies interactions between blocks were also observed, including higher Douglas-fir seedling survival in mixed stands compared to pure Douglas-fir, large effects of naturally regenerating hemlock, and reduced salal cover associated with increased alder cover. These somewhat subtle interim results suggest that fine-tuning sites or altering early-seral strategies for different sites will be important in more widely adopting plantations geared to restoring early-seral elements in these intensively managed systems.
Using a tightly controlled, forested GPS test course located in Athens, Georgia, two smartphones, an iPhone 13 Pro (iOS) and Google Pixel 6 Pro (Android), were assessed to better understand their positional accuracy under different forest conditions and stand types. Additionally, a high precision external GNSS antenna was also assessed. With a focus on how professional foresters typically use their smartphones when collecting Global Navigation Satellite System (GNSS) data in the forest (i.e., single static position fixes, at approximate waste height, and with minimal wait times before collection), we found that, generally, the root mean square error (RMSE) (m) of both the iPhone 13 Pro and Google Pixel 6 Pro were statistically significantly different, with the Google Pixel 6 Pro outperforming the iPhone 13 Pro by 1 to 3 m in both an older natural loblolly pine (Pinus taeda) stand and in an older mixed upland hardwood stand under leaf-off and leaf-on conditions. Forestry professionals, on average, may expect between 2 to 6 m accuracy when using a smartphone in some southern forests. If one is capable of making an additional investment, a high precision external antenna that can be coupled with both iOS and Android devices at a cost comparable to mapping-grade GNSS receiver technology, may consistently achieve submeter accuracy in some forests without the need for real time kinematic (RTK) assistance. Awareness of the uncertainty associated with smartphones is important when incorporating these data into more advanced forestry applications.
Wildfires can cause prolonged disruptions to public land access, affecting nearby local economies. As recreationists with varying levels of knowledge of wildfire increasingly visit fire-prone areas, reaching diverse audiences through non-traditional communication channels like local businesses offers novel opportunities for increasing engagement and outreach capacity. Business preparation for wildfire risk is central to developing fire adapted communities, yet little qualitative research has sought to capture their role in broader efforts to mitigate risks and impacts. We conducted semi-structured interviews with local business owners and employees, land managers, government representatives, and economically oriented local non-profits to explore how local businesses in Flagstaff, Arizona, USA, navigate wildfire impacts and to better characterize their role in human-caused wildfire prevention education. We found that local businesses experienced varying wildfire-related impacts defined by their relationships to, and dependence on, public lands for revenue, and were already informally acting as community stewards of fire prevention education but lacked the resources to develop cohesive and accurate messaging. We also offer recommendations for more intentional partnerships between businesses and agencies to leverage prevention education capacity and extend the scale and scope of outreach to public land users. Together, these findings can inform a more concerted approach to human-caused wildfire prevention that protects the interdependent relationship between public land management, wildfires, and local economy.
We present a case study where loggers thinned and managed brush in longleaf pine stands that went unmanaged for a lengthy period in Trinity County, Texas, USA. Stands were overstocked and had a dense, shrubby understory from years of fire exclusion. Our main objectives were to compare the outcomes and cost-savings of loggers selecting trees to thin, or “operator select”, versus timber marking, and whether they were different when attempting to restore longleaf pine stands to an open structure. We also worked closely with loggers to manage brush in place of conventional forestry mulching as a source of additional cost-savings. Twenty-one inventory plots were sampled during prethinning and post-thinning treatment stages, with half marked and the other half left unmarked. The location of unmarked plots was undisclosed to loggers and harvested by operator select methods. We measured no significant difference in forest inventory metrics at marked and unmarked plots following thinning. There was, however, better retention of longleaf pine and removal of loblolly pine in marked areas, and overall precision was higher in marked areas. QMD increased across all plots, woody vegetation decreased significantly, and reestablishment of herbaceous groundcover increased after following thinning with prescribed burning. Using this approach, an estimated 197.53 US per hectare cost for timber marking and879.34 US per hectare for conventional mulching services was saved. After reimbursing loggers for brush management services, this amounted to an estimated 876.35 US per hectare reduction in project cost to create open longleaf pine structure. When implementing operator select in longleaf pine stands, our results indicate that providing feedback to well qualified loggers can create comparable results to timber marking at a discounted cost, but with small tradeoffs in precision.
Given the increasing proportion of loblolly pine plantations established with genetically improved material, it is essential to incorporate genetic gains into growth and yield (G Y) modeling to better reflect genetic influence. This study evaluated the appropriateness of using genetic gain multipliers to incorporate gains into a stand model system (Phase_I), which was originally developed from plantations established with unimproved or low-level improved seed lots in the late 1970s or early 1980s in the western Gulf region. Height gain multipliers were adjusted using age–age genetic correlations to account for the declining nature of relative genetic gain with age. Modeled outputs were then compared with predictions from a more recent stand model (Phase_II), developed from plantations established using improved genetics in the 2000s, as well as with observed genetic gains from two family tests. Results indicated that the gain-multiplier approach, when paired with age–age correlation adjustments, can be effective but tends to overestimate stand volume. While applying the method to integrate gains into G Y modeling is relatively straightforward technically, the greater challenge lies in obtaining accurate estimates of realized genetic gain from deploying improved material across operational landscapes. This study highlights the importance of establishing realized gain trials; however, in the absence of such data, we recommend reducing estimated gains by 30–40
Eastern redcedar (Juniperus virginiana; ERC) encroachment in upland xeric oak forests of the Cross Timbers ecoregion may raise fire risk due to increased fuel loading and ladder fuels. However, the magnitude of fire risk is not well known or defined. Effects of common ERC mechanical treatments are also not well understood in upland xeric oak forests with ERC encroachment. We burned 65 plots approximately two months after applying mechanical treatments across five forest stands to better understand prescribed fire behavior under controlled and monitored conditions. Our results indicated individual fuel loading classes did not significantly affect maximum flame height. However, flame height was higher in areas with more dead ERC fuels, higher live crown ratio and high total fuel loading, whereas flame height was lower with more live ERC and higher basal area. Our ERC treatments were intended to emulate common management techniques addressing species composition, forest health and wildfire mitigation. ERC mechanical treatment which increases dead ERC fuel loading prior to using prescribed fire may result in increased fire intensity. This information is helpful for state and private non-industrial forest landowners with multiple-use objectives. Landowners and land managers in the Cross Timbers ecoregion are often concerned with controlling ERC for xeric oak forest maintenance and wildfire mitigation. Considering the rate of ERC encroachment in upland xeric oak forests, properties with wildlife, livestock, and recreation goals increasingly require active land management to reduce the degree of encroachment. Our study confirmed that mechanical treatment of ERC necessitates careful planning of subsequent prescribed fire for ecosystem maintenance. Considerations for future oak forest managers include understanding how fire behavior changes in response to both ERC encroachment and active ERC management.
Accelerating the development of more heterogeneous forest structures is an important goal of many contemporary forest management regimes. However, long-term silvicultural experiments that compare different approaches to generating structural complexity are rare. We took advantage of a replicated silvicultural experiment that was established in mountain ash (Eucalyptus regnans) forests in southeastern Australia in the late 1980s. We evaluated multi-decadal forest development responses to seven different silvicultural treatments: clearfelling (clearcutting), seed tree, three gap sizes (0.25, 0.5, and 2 ha), and two levels of overstorey retention (30
Many landowners in the US South planted loblolly pine at a time of rising stumpage prices as the US forest economy shifted to the South. Subsequent events restructured the region’s forest industry, and persistently lower and flat timber prices have many concerned for their forest investment. Southern pine timber product price trends and volatilities over periods of 25 to 40 years were incorporated into loblolly pine plantation discounted cash flow analyses at real discount rates [DR] of 4.00
Research on vegetative propagation in the genus Khaya remains limited and has focused mainly on juvenile trees, which restricts the selection of plus trees previously tested for growth potential and economic value. This study aimed to evaluate the vegetative propagation of three African mahogany species by inducing epicormic shoots in adult trees, and to investigate evidence of rejuvenation/reinvigoration during adventitious rooting, as well as the influence of branch diameter on bud and shoot emission. Plant material was collected from an experimental plantation using basal branches of 10-year-old trees. For each species, 72 leafless branches were standardized and maintained in a climate-controlled greenhouse. The experiment followed a completely randomized design with three diameter classes. After 21 days, the number of buds and shoots emitted per branch was recorded. Biochemical analyses included the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), total proteins, and total carbohydrates to characterize metabolic differences between adult tissues and epicormic shoots. Results indicate that branch diameter had a significant effect on bud and shoot emission in all three African mahogany species, with branches 4.5–6 cm in diameter being the most suitable source material. For assessing tissue rejuvenation and metabolism, SOD and CAT activities in K. senegalensis, SOD activity in K. grandifoliola, and total carbohydrate content in K. ivorensis were the most responsive biochemical variables for distinguishing epicormic shoots from adult tissues. Although adventitious rooting percentages were low, this study indicates that epicormic shoot induction in adult trees is a feasible strategy for obtaining vegetative propagules.
Tornadoes drastically impact managed forest landscapes, altering structure, composition, and economic valuation. Tornadoes occur frequently in the US and are projected to increase in the southeastern region, which is a substantial timber-producing region. Quantifying tornado damage in managed forest landscapes is important for guiding management decisions and modeling recovery efforts to recoup economic losses. We assessed the spatiotemporal effects on forest structure, volume, and carbon in 13–17 year old loblolly pine (Pinus taeda L.) stands after an EF-3 tornado, with a path length of 35 km long and damage swath of 250 m wide, in Shallotte, North Carolina, US. We established 36 plots along a tornado path and reconstructed pre-storm stand characteristics to compare them to the first and third growing seasons (2021 and 2023) after the storm. To evaluate the spatial distribution of damage, we sampled directly in the tornado’s path, along its edge, and in undisturbed, adjacent forest areas within the same stand. We found that damage was localized, reducing trees per hectare, basal area, volume, and aboveground carbon stock by 50
Stem diameter distributions underpin forest planning and inventory practice worldwide, yet permanent sample plot inventories are routinely truncated by merchantability limits and diameter caps. Truncated densities are the standard remedy, but those forms are seldom documented or supported in common software, so practitioners default to biased complete-form fits. We introduce a two-stage weighted least-squares workflow that retains the familiar complete-form implementation while recovering truncated-fit accuracy. Stage one estimates a scaling factor alongside the density parameters; stage two freezes that normaliser to deliver unbiased shape and scale estimates. Applied to fixed-area plots from Québec, Canada, the two-stage estimator tracks truncated Weibull and gamma fits across 32 species-group/cover-type combinations (root-mean-square error between one-stage truncated and two-stage complete fits: 2× 10^-5 – 3.7× 10^-2 ) and yields the lowest stage-2 AICc (small-sample Akaike information criterion) in 25 of 32 cases. The companion repository provides the tallies, scripts, and notebooks required to regenerate every figure, table, and LaTeX artefact.
Foliar moisture content (FMC) plays a crucial role in arid, frequent-fire forests by influencing fire behavior, tree survival, and serving as a proxy for tree health. Management actions such as mechanical thinning, flammable fuels reduction, and prescribed fires can act to mitigate wildfire risk and improve forest health by reducing fuel connectivity, diversifying forest structure, and creating canopy gaps. These management actions could be improved by the targeted removal of moisture stressed and potentially more flammable trees during treatments. However, maps of FMC are not widely available at the tree-level, with no existing products to map FMC of western conifers at the stand-level (< 0.25 m). This project focuses on the scalability of laboratory-developed models predicting sapling FMC to develop and assess tree-level FMC in natural forest conditions. Specifically, we tested whether existing FMC models accurately predict individual tree FMC using uncrewed aerial system (UAS) data. While laboratory-developed models did not translate well to field sites, a field-developed model achieved a mean absolute error of 6.5
Peat extraction for nursery substrates contributes to carbon emissions and peatland destruction, highlighting the need for sustainable alternatives such as biochar. In this study, we evaluated how biochar substitution of peat (0–100
The Leaf Area Index (LAI) is a key ecological variable for monitoring land surface processes and plays an important role in understanding climate-sensitive forest ecosystems such as the Hyrcanian forests. This study aimed to estimate LAI using Linear Mixed-Effects (LME), M5 Model Tree (M5), Random Forest (RF), and Multiple Linear Regression (MLR) algorithms based on Landsat-8 and Sentinel-2 satellite data in the hardwood Hyrcanian forests located in Golestan Province, northern Iran. A total of 230 plots were established across five forest sites using a 100 × 100 m systematic grid. Specific Leaf Area (SLA) was measured for each tree species at each site, and LAI was subsequently estimated from these measurements. Results indicated that mean LAI values across the five sites ranged from 5.1 to 8.9. Among the algorithms, LME yielded the most accurate LAI estimates when applied to Landsat-8 data (RMSE = 22.32
Bark beetles contributing to ponderosa pine mortality in western North America are ecologically and economically impactful. Future climate patterns are expected to exacerbate these impacts. While reactive management aims to reduce the impact of bark beetle-caused tree mortality after these insects have already entered a forest system, preventative measures can serve to reduce the susceptibility of forested stands to epidemic bark beetle attacks before they occur. It is well documented that stressed trees are more susceptible to beetle attack and subsequent mortality than healthy trees. For this reason, nearly a century of research has been focused on the identification of quantifiable characteristics that serve as proxy variables indicative of tree stress. Dozens of bark beetle susceptibility models exist, though they vary widely in their use of variables, application, predictive capabilities, and region of interest. This review serves to identify bark beetle susceptibility models for ponderosa pine forests in western North America, highlight their limitations, and outline the improvements that can be made in the development of future susceptibility models.
Understanding how tree growth responds to climate is important for predicting how plantation forests may react to ongoing climate change. In this study, we examined the climate–growth relationships of six Cryptomeria japonica cultivars across five common-garden sites in southwestern Japan using dendrochronological methods. We analyzed 48 years of ring width data to evaluate how monthly and annual temperature and precipitation affect radial growth at site and cultivar levels. Static and moving correlation analyses revealed that late winter to early spring temperatures (February–March) positively influenced radial growth at most sites, likely by facilitating cambial reactivation, while high summer precipitation tended to suppress growth at some sites, possibly through reduced solar irradiance. Precipitation effects were variable across sites, with autumn rainfall showing positive effects at lower-elevation sites. At the cultivar level, early-growth type cultivars tended to show positive temperature responses, while late-growth types showed more variable precipitation responses, though the majority of cultivar-level correlations did not reach statistical significance. Multivariate ordination (PCA) and permutational multivariate analysis of variance (PERMANOVA) on correlation-based response profiles indicated that geographic location was a significant driver of climate-growth response patterns (R2 = 0.28, p = 0.014), while cultivar type explained a substantial but non-significant proportion of variance (R2 = 0.23, p = 0.085). These results suggest that local environmental conditions primarily shape climate sensitivity in C. japonica, while genetic provenance provides an additional, non-negligible layer of variation. Our findings underscore the importance of considering both site characteristics and cultivar characteristics in forest management and climate adaptation strategies for C. japonica plantations.
Management of pine-hardwood mixtures or mixedwood forest types is gaining interest in the southeastern United States where landowner objectives/attitudes, rising management costs, timber and carbon markets, and logging workforce factors may provide rationale for favoring these forest types. However, few studies in the region have documented long-term stand development patterns for pine-hardwood mixtures. The objectives of this study were to 1) evaluate ten-year survival and growth of planted shortleaf pine (Pinus echinata) following four site preparation and early release treatments, and 2) assess the associated natural regeneration composition and growth. A study area was established during 2013/2014 near Estill Springs, Tennessee. Fell-and-burn site preparation served as the control treatment, and three additional first and/or second year release treatments were tested. Shortleaf pine seedlings were planted at two spacings (3.6 × 3.6 m and 5.5 × 5.5 m). Results indicated a significant treatment x spacing interaction for shortleaf pine survival (P = 0.01) with improved survival observed in the 3.6 × 3.6 m spacing herbicide release treatments. Average height growth was statistically significant (P = 0.01) and greater in the herbicide-and-burn release treatment (8.1 m) compared to the control (6.8 m) and burn release (6.8 m) treatments. Invasive woody species were more common than other species groups, but they were significantly shorter than native woody species (P < 0.001). Treatments that included herbicide release resulted in greater shortleaf pine survival and height growth. Oaks (Quercus spp.) and other Pinus spp. were present in upper crown classes in the two herbicide release treatments after ten years, but additional management will be needed to suppress invasive woody species as these stands continue to develop.
A crop tree management study targeting green ash (Fraxinus pennsylvanica Marsh.) was established in a 16-year-old, naturally regenerated, mixed-species, bottomland hardwood stand in southwest Tennessee. The goal was to maintain or improve ascendance of green ash into the overstory of a developing stand that otherwise might not occur. Three treatments were examined: a complete crown-touching release; the same release treatment along with a one-time, fertilizer application; and a control. Initial diameters, heights and crown size parameters were measured in 1996 and 18 years later. The two release treatments did not differ significantly in diameter and height growth response, but statistically outperformed the control treatment. Similarly, crown class scores did not differ between the two release treatments, but were significantly improved from the control. Both release treatments displayed a greater percentage of crop trees successfully competing for upper canopy status compared to the control. Using initial tree diameter as a reflection of crown size and position of crop trees, diameters of 12.5 to 20 cm were more likely to be a component of the overstory 18 years following crop tree treatments. Crop trees less than 12.5 cm in diameter were likely to remain in the subordinate crown classes. Trees greater than 20 cm in diameter were already in the overstory and maintained their upper canopy position. These results suggest that crop tree management can be an effective management tool for improving growth as well as improving overstory presence of green ash in pole-sized, mixed-species, bottomland hardwood stands.
Monoculture Hevea brasiliensis plantations often exhibit reduced soil nitrogen (N) and soil organic carbon (SOC) levels due to insufficient vegetation cover. To improve management, we evaluated the effects of intercropping with the legume Centrosema pubescens (C. pubescens) and retaining natural weeds on soil N and SOC variation in inter-rows (between tree rows) and intra-rows (within tree rows). We measured SOC, total N, available N, ammonium N (NH₄⁺-N), and nitrate N (NO₃⁻-N) monthly (July-December 2018) at 0–60 cm depth in a 14-year-old plantation during three years. We used four treatments: C. pubescens in inter-rows (Inter-CP), no legume in intra-rows (Intra-CP), weeds in inter-rows (Inter-W), and no weeds in intra-rows (Intra-W). All parameters varied significantly with depth and time. The average concentrations of SOC, total N, available N, NH₄⁺-N, and NO₃⁻-N in the 0–60 cm profile were significantly higher under Inter-CP than under Inter-W. Available N and NO₃⁻-N accumulated in greater amounts in inter-rows than in intra-rows. Total N and available N levels were linked to seasonally fluctuating total N reserves. Centrosema pubescens and natural weeds increased inorganic N availability in their respective inter-row settings; however, the legume provided a greater supply. Therefore, planting C. pubescens and/or maintaining weed cover in inter-rows is recommended to enhance soil N and C accumulation and improve long-term plantation productivity.
Bark-stripping by Chacma baboons (Papio ursinus) presents a significant threat to the productivity and economic viability of commercial pine plantations in South Africa. This study examined the occurrence, characteristics, and impacts of baboon damage across 23,928 trees from 23 sites monitored for at least five consecutive years. The proportion of affected trees varied widely among sites (8–87
