Loblolly Pine Plantations Research Articles

Plant size dependent response of native tree regeneration to landscape and stand variables in loblolly pine plantations in the Atlantic Forest, Argentina

The interest in the conservation of biodiversity in productive ecosystems has increased considerably in recent years due to the continuing loss of natural vegetation. The effect of forest plantations on biodiversity is currently a relevant research topic since they are expanding worldwide. Native understory vegetation may maintain ecosystem processes and increase the availability of habitats, food and other resources for different animal groups. Native tree regeneration in plantations is affected by the planted species, stand age and density, and silvicultural practices, among others. Despite that some general trends have been identified, results from different studies are not always comparable, partially because not all sources of variation were considered simultaneously, the size of plants is different between studies, no different classes of plant sizes are compared, or the local flora determines specific responses to landscape and stand variables. In this work, we analyzed the relationship between native tree density, species richness and species composition in the understory of forest plantations and stand characteristics including stand age and density, canopy openness, proximity to native forests remnants and pre-planting land use history. The study was conducted in monoculture plantations of Pinus taeda in Misiones Province, Northeastern Argentina. In 35 stands, we estimated plant density and species richness for three plant size classes: seedlings (>50 cm height and <1 cm in diameter at breast height (DBH)), saplings (1–5 cm DBH) and small trees (5–10 cm DBH). Our results are in agreement with general trends previously reported in the study area and worldwide. We found that native trees in the plantations showed a strongly size-dependent response to stand and landscape variables. The composition and richness of the seedlings were primarily dependent on the native forest cover at a landscape scale while the species composition, richness, and density of saplings and small trees were mainly affected by stand age and density. Our results showed that the management of pine plantations should maintain the rotation for more than 20 years, a basal area below 30 m2·ha−1 and a 25–30% of native forest cover at the landscape scale to increase the richness and density of the native trees in loblolly pine plantations of the Atlantic Forest.

Recalling open old growth forests in the Southeastern Mixed Forest province of the United States

ABSTRACTHistorical forests in the Southeastern Mixed Forest province of the United States have been less researched than other regions using historical tree surveys. We used 81,000 tree records from surveys during the 1800s to quantify composition of this ecological province. Upland oaks and pines comprised about 75% of all trees, with relatively equal composition. Oak composition may have comprised ≥ 45% to the northern and eastern sides of the province. Hickories were about 10% of composition and a few species were present at 1% to 2% composition. Currently, pine has increased to 49% composition; loblolly pine was 46% of all trees. Upland oaks decreased to 8% composition. Paralleling other historically oak- or pine-dominated regions, fire-intolerant species increased to 40% of composition, particularly early-successional sweetgum. Historical oak-pine forests mostly have converted to loblolly pine plantations and broadleaf forests in this region. A large extent of the eastern United States historically was dominated by oak or pine forests, which likely were open old growth forests due to a frequent, low-to-moderate severity fire regime that reduced tree densities and infrequently disturbed overstory trees. Open old growth forests should be recognized as distinct ecosystems with unique characteristics, ecological functioning, and associated management practices.

Carbon balance and economic performance of pine plantations for bioenergy production in the Southeastern United States

Management strategies for loblolly pine (Pinus taeda) plantations in the Southeastern USA can be adapted to fulfill both the demand for wood products and for bioenergy. This study quantifies the impact of plantation management choices on the cumulative carbon balance and the net present value of loblolly pine plantations at the stand level, as well as the wood supply cost for bioenergy production for these different management strategies. The strategies assessed (conventional, additional thinning and short rotation) are characterised by planting density, thinning age and rotation period, each with and without collection and utilization of slash residues for bioenergy. The total wood supply costs for bioenergy include the cultivation, harvesting and transport costs for small diameter trees and slash. The results show that the carbon balance after 100 years is 205 (247), 214 (268) and 149 (195) Mg ha−1 for the conventional, additional thinning, and short rotation loblolly pine plantation management strategies (within parentheses: same strategies with slash utilization). The conventional strategy has the lowest wood supply costs for bioenergy, 47 (46) $ Mg−1 pulpwood, followed by the additional thinning strategy, 50 (49) $ Mg−1 pulpwood, and 54 (52) $ Mg−1 pulpwood for the short rotation management strategy. In conclusion, switching from the current conventional strategy without the utilization of slash for bioenergy to an additional thinning strategy with the use of slash increases the overall carbon accumulation by about 31%, at marginally higher wood supply cost. Adapting plantation management strategies can have a positive effect on the economic performance and on the carbon balance of loblolly pine plantations. Integration of wood supply for bioenergy and traditional forestry sectors can lead to co-benefits in terms of cost reduction and carbon accumulation.

Effect of nitrogen addition and litter removal on understory vegetation, soil mesofauna, and litter decomposition in loblolly pine plantations in subtropical Argentina

Loblolly pine monocultures have been increasingly expanding in the Atlantic Forest of South America especially in northern Argentina. Pine plantations can modify understory vegetation and soil characteristics due to the management practices and to the dense mulch of pine needles that develop in the forest floor that could affect soil biota and ecosystem processes. Nitrogen (N) addition as expected as atmospheric deposition can also contribute to these changes. The aim of this study was to assess the effect of litter removal and low levels of N addition on understory regeneration, soil mesofauna abundance, and leaf litter decomposition. For this purpose, a completely randomized block design was used. Nitrogen addition had significant effects on understory regeneration promoting creeping herbs, graminoids and shrubs life forms affecting tree establishment and growth. Litter removal treatment showed the same pattern but only promoting the creeping herbs that could also have affected tree species. Decomposition decreased due to litter removal and was slightly increased by N addition. The addition of N decreased the abundance of mesofauna in the mulch, especially Symphypleone (a suborder of Collembola), but the abundance of the soil communities was not affected. Litter removal had a strong impact on these communities because most individuals and species of the mesofauna are present in the litter and not in the soil. This is one of the first studies analyzing the effect of low amounts of N addition and litter removal in subtropical pine plantations and contribute to understand potential impacts of increasing N deposition on biodiversity and soil processes, and to select organisms that may help as bioindicators in assessing impacts on ecological functions in productive ecosystems.

Changing Times: Altering Establishment Spacing, Harvesting Frequency, and Harvesting Machines to Promote Increased Sawtimber Volumes

Today’s landowners are faced with important decisions when establishing loblolly pine plantations in the Southeastern part of the United States with regards to planting dimensions and forest management techniques. Although recent studies are beginning to demonstrate the need for change from the old practices, suppressed biomass markets and prices are hindering the transition. This paper provided readers with an informational overview of the benefits of: incorporating an additional thinning regime for biomass, using alternate spacing methods such as FlexstandsTM and rectangularity, and using small-scale harvesting machines for conducting initial thinning’s. The overview was supported with both a field study as well as a modeling tool which verified using one or all of the above-mentioned techniques to increase total harvest volumes while minimizing residual stand damage. The modeling tool determined that final sawtimber volumes were increased by a minimum of 15 tons per acre using one or more of the above techniques. When expanding this volume out to 20 acres, the minimum tract size harvested in the southeast using convention equipment, landowners could easily recover any losses incurred from the suppressed biomass markets minimizing overall risk and promoting the use of these alternative techniques.

Models for Predicting Specific Gravity and Ring Width for Loblolly Pine from Intensively Managed Plantations, and Implications for Wood Utilization

Loblolly pine (Pinus taeda L.) is increasingly grown on intensively managed plantations that yield high growth rates. Wood properties, including specific gravity (SG), change with cambial age, and thus intensively managed trees contain a high proportion of low density corewood when harvested because of reduced rotation lengths. This study was undertaken to develop models of ring-level properties (SG and width) in intensively managed loblolly pine plantations. Ninety-three trees from five stands aged from 24 to 33 years were harvested, and 490 disks were obtained from in between the 5.2-m logs that were cut, and at the merchantable top. The disks were cut into pith-to-bark radial strips that were scanned on an X-ray densitometer, and the resultant data analyzed using non-linear mixed-effects models. The fixed effects of the models, which included cambial age and for some models disk height and ring width, were able to explain 56, 46, 54, 16, and 46 percent of the within-tree variation for ring SG, ring width, latewood SG, earlywood SG, and latewood percent, respectively. To assess implications for wood utilization, a modeled tree was built by using height, diameter, and taper equations and these models were linked with the developed ring SG model to produce a tree properties map. The linked information was also used to generate tree and log SG and proportion of corewood values for different rotation ages. The results from this study are a step towards integrating wood quality models into growth-and-yield modeling systems that are important for loblolly pine plantation management.

Using Bayesian methodology to incorporate personal knowledge when estimating average tons per acre of loblolly pine plantations

Foresters often don rsquo t fully utilize available information when estimating average stand tons ac ndash Previous experience and if available historic inventory data of the same tract or similar tracts can be used as prior information in a Bayesian context to reduce uncertainty associated with average ton estimates Bayesian methods produce a posterior distribution dependent both on the current forest inventory sample and prior information about the probabilities associated with any one average tons ac ndash actually being the true average tons A more complete description and background of using Bayesian methods to incorporate personal knowledge when estimating average tons is provided Additionally a practical example using data obtained from an actual forest inventory conducted in a loblolly pine Pinus taeda L plantation is presented Using conventional variable plot sampling techniques average tons was estimated at tonsac ndash However when determining a posterior distribution using a Beta distribution to quantify prior personal knowledge of similar sites the estimate of average tons changed to tons ac ndash When using a Uniform distribution to quantify prior knowledge the estimated average tons did not change For this example ton estimates were not substantially changed when using a Bayesian approach however the inferential statements that can be made about the true average tons are different than when using a frequentist inference approach

Carbon accumulation in loblolly pine plantations is increased by fertilization across a soil moisture availability gradient

Silvicultural practices, particularly fertilization, may counteract or accentuate the effects of climate change on carbon cycling in planted pine ecosystems, but few studies have empirically assessed the potential effects. In the southeastern United States, we established a factorial throughfall reduction (D) × fertilization (F) experiment in 2012 in four loblolly pine (Pinus taeda L.) plantations encompassing the climatic range of the species in Florida (FL), Georgia (GA), Oklahoma (OK), and Virginia (VA). Net primary productivity (NPP) was estimated from tree inventories for four consecutive years, and net ecosystem productivity (NEP) as NPP minus heterotrophic respiration (RH). Soil respiration (RS) was measured biweekly-monthly for at least one year at each site and simultaneous measurements of RS & RH were taken five to eight times through the year for at least one year during the experiment. Reducing throughfall by 30% decreased available soil water at the surface and for the 0–90 cm soil profile. Fertilization increased NPP at all sites and D decreased NPP (to a lesser extent) at the GA and OK sites. The F + D treatment did not affect NPP. Mean annual NPP under F ranged from 10.01 ± 0.21 MgC·ha−1·yr−1 at VA (mean ± SE) to 17.20 ± 0.50 MgC·ha−1·yr−1 at FL, while the lowest levels were under the D treatment, ranging from 8.63 ± 0.21 MgC·ha−1·yr−1 at VA to 14.97 ± 0.50 MgC·ha−1·yr−1 at FL. RS and RH were, in general, decreased by F and D with differential responses among sites, leading to NEP increases under F. Throughfall reduction increased NEP at FL and VA due to a negative effect on RH and no effect on NPP. Mean annual NEP ranged from 1.63 ± 0.59 MgC·ha−1·yr−1 in the control at OK to 8.18 ± 0.82 MgC·ha−1·yr−1 under F + D at GA. These results suggest that fertilization will increase NEP under a wide range of climatic conditions including reduced precipitation, but either NPP or RH could be the primary driver because F can increase stand growth, as well as suppress RS and RH. Moreover, D and F never significantly interacted for an annual C flux, potentially simplifying estimates of how fertilization and drought will affect C cycling in these ecosystems.

Effect of pulp and paper mill sludge on the development of 17-year-old loblolly pine (Pinus taeda L.) trees in Southern Brazil

Pinus taeda is a principal conifer tree species and has long been used in forest plantations in Southern Brazil. At the same time, experiments have been carried out in order to determine the wood productivity concerning the economic, social and sustainable forest management practices. In that sense, the organic fertilizers, such as the biosolid residues from pulp and paper industries, are one of the alternatives to achieve this sustainability. Nevertheless, few studies addressing this objective have been reported in Brazil. This study aimed to analyze the growth responses of loblolly pine trees treated with different doses of composted pulp-mill sludge and to propose a management guide based on a wood production simulation. A randomized block design with four replicates for every six treatments - control, 20, 40, 60, 80 and 100 t ha−1 of composted pulp-mill sludge - were carried out in an experimental plantation located in Arapoti, Paraná state, Brazil. Ten 17 year-old-trees for each treatment were selected, the stem variables were analyzed and the stand wood productivity for the optimal dosage was simulated. The trees were significantly influenced by the application of the composted pulp-mill sludge, increasing up to 24, 37 and 127% in stem diameter, height and volume, respectively, and the rotation of the pine plantation control and treated stands was 33 and 21 years, respectively. The forest management applied for a 21-year harvesting cycle (thinning at 7 and 13 years) with 84 t ha−1 of composted pulp-mill sludge resulted in a wood productivity of 11.9 m3 ha−1 or 5.04 Mg ha−1 per year. The results confirm the potential application of pulp-mill sludge as a fertilizer to improve the wood productivity of forest plantations established in poor-nutrient sites. Also, the forest management plans, using the guide proposed, could be replicated in loblolly pine and other tree species plantations according to the end use of wood.

Variability of sun-induced chlorophyll fluorescence according to stand age-related processes in a managed loblolly pine forest.

Leaf fluorescence can be used to track plant development and stress, and is considered the most direct measurement of photosynthetic activity available from remote sensing techniques. Red and far-red sun-induced chlorophyll fluorescence (SIF) maps were generated from high spatial resolution images collected with the HyPlant airborne spectrometer over even-aged loblolly pine plantations in North Carolina (United States). Canopy fluorescence yield (i.e., the fluorescence flux normalized by the light absorbed) in the red and far-red peaks was computed. This quantifies the fluorescence emission efficiencies that are more directly linked to canopy function compared to SIF radiances. Fluorescence fluxes and yields were investigated in relation to tree age to infer new insights on the potential of those measurements in better describing ecosystem processes. The results showed that red fluorescence yield varies with stand age. Young stands exhibited a nearly twofold higher red fluorescence yield than mature forest plantations, while the far-red fluorescence yield remained constant. We interpreted this finding in a context of photosynthetic stomatal limitation in aging loblolly pine stands. Current and future satellite missions provide global datasets of SIF at coarse spatial resolution, resulting in intrapixel mixture effects, which could be a confounding factor for fluorescence signal interpretation. To mitigate this effect, we propose a surrogate of the fluorescence yield, namely the Canopy Cover Fluorescence Index (CCFI) that accounts for the spatial variability in canopy structure by exploiting the vegetation fractional cover. It was found that spatial aggregation tended to mask the effective relationships, while the CCFI was still able to maintain this link. This study is a first attempt in interpreting the fluorescence variability in aging forest stands and it may open new perspectives in understanding long-term forest dynamics in response to future climatic conditions from remote sensing of SIF.

Distance error for determining the acoustic velocity of standing tree using tree morphological, physical and anatomical properties

Time-of-flight (ToF) acoustic tools is one of the most practical nondestructive methods for predicting tree stiffness. In the literature, 120 cm between probes has been adopted as the standard for the assessment of tree acoustic velocity. However, there is no empirical study supporting this assertion, hence this study is aimed at determining the effect of distance on error for a common ToF acoustic tool. Twenty-five trees each were randomly selected from four loblolly pine plantations. Seven distances from 120 to 10 cm between probes were used to measure velocity. The morphological characteristics, physical and anatomical properties of the selected trees were also determined. The results indicated, at distances below 60 cm, the waveform is dominated by the fundamental frequency of the transmitter probe hence the velocities determined within 10–60 cm are not statistically different. Consequently, distances from 80 to 120 cm constitute the optimum range for velocity determination for this ToF acoustic tool. Furthermore, velocity determined at 40 cm is significantly higher than that determined at 120 cm suggesting velocity is dependent on the between probes distance. Using 120 cm as a standard distance, the dynamic stiffness is overestimated by 13, 50, 102, and 197 MPa respectively for 100, 80, 60, and 40 cm. Finally, microfibril angle and the fiber wall thickness are the main anatomical properties driving the signal at the micro-level.

Trapping for Sirex Woodwasp in Brazilian Pine Plantations: Lure, Trap Type and Height of Deployment

The Sirex woodwasp, Sirex noctilio (Hymenoptera: Siricidae) is considered a secondary pest of pine in its native range but has caused considerable economic losses in pine plantation forests in the southern hemisphere. In Brazil, trap trees are the primary tool used for early detection purposes but these are costly, labor-intensive to install and require stressing trees by herbicide application. Flight intercept traps baited with synthetic blends of host volatiles are an attractive alternative but have performed poorly in some settings. This study was carried out to look for alternatives to trap trees for use in Brazilian pine plantations for early detection of S. noctilio. Four field experiments were conducted in two consecutive flight seasons (2015–16 and 2016–17), in planted loblolly pine (Pinus taeda) stands, to compare captures among flight intercept traps baited with different lures, deployed at different heights and among different intercept trap designs. Two experiments compared different host volatile lures and a significant treatment effect was observed in one. No effect of trap design or height was observed.

Surface and Subsurface Tillage Effects on Mine Soil Properties and Vegetative Response

Core Ideas Mine soil physical properties improve with increased tillage upon reclamation in the Gulf Coastal Plain. Growth of loblolly pine seedlings increases with higher intensity tillage on reclaimed mined land. Aboveground herbaceous cover and biomass increases with tillage on reclaimed mined land. Soil compaction is an important concern for surface mine operations that require heavy equipment for land reclamation. Excessive use of rubber‐tired equipment, such as scraper pans, may cause mine soil compaction and hinder the success of revegetation efforts. However, information is limited on management strategies for ameliorating the potential compacting effects of scraper pans, particularly during site preparation for loblolly pine (Pinus taeda L.) plantations. Three forms of tillage and one control were replicated five times on surface mined land in the west Gulf Coastal Plain: no tillage (NT), disking (D), single‐ripping + disking (R+D), and cross‐ripping + disking (CR+D). Mine soil physical properties were investigated at 0 to 30, 30 to 60, and 60 to 90 cm. Percent cover and aboveground biomass of an herbaceous winter cover crop, and survival and growth of loblolly pine seedlings were assessed after one growing season. Herbaceous species biomass was highest on the R+D and CR+D plots and lowest on the NT control. Pine seedling survival was highest on the tilled plots (&gt;90%) compared to NT (85%). The highest intensity combination tillage treatment (CR+D) was superior in terms of lowering soil bulk density (mean 1.36 Mg m–3) and soil strength (mean 2220 kPa) and increasing pine seedling volume index growth (mean 32 cm3). Surface tillage (D) alone improved herbaceous cover and pine seedling survival, while CR+D provided the most favorable responses in mine soil physical properties and vegetative growth.

Modelling the effect of changing precipitation inputs on deep soil water utilization

AbstractForests in the Southeastern United States are predicted to experience future changes in seasonal patterns of precipitation inputs as well as more variable precipitation events. These climate change‐induced alterations could increase drought and lower soil water availability. Drought could alter rooting patterns and increase the importance of deep roots that access subsurface water resources. To address plant response to drought in both deep rooting and soil water utilization as well as soil drainage, we utilize a throughfall reduction experiment in a loblolly pine plantation of the Southeastern United States to calibrate and validate a hydrological model. The model was accurately calibrated against field measured soil moisture data under ambient rainfall and validated using 30% throughfall reduction data. Using this model, we then tested these scenarios: (a) evenly reduced precipitation; (b) less precipitation in summer, more in winter; (c) same total amount of precipitation with less frequent but heavier storms; and (d) shallower rooting depth under the above 3 scenarios. When less precipitation was received, drainage decreased proportionally much faster than evapotranspiration implying plants will acquire water first to the detriment of drainage. When precipitation was reduced by more than 30%, plants relied on stored soil water to satisfy evapotranspiration suggesting 30% may be a threshold that if sustained over the long term would deplete plant available soil water. Under the third scenario, evapotranspiration and drainage decreased, whereas surface run‐off increased. Changes in root biomass measured before and 4 years after the throughfall reduction experiment were not detected among treatments. Model simulations, however, indicated gains in evapotranspiration with deeper roots under evenly reduced precipitation and seasonal precipitation redistribution scenarios but not when precipitation frequency was adjusted. Deep soil and deep rooting can provide an important buffer capacity when precipitation alone cannot satisfy the evapotranspirational demand of forests. How this buffering capacity will persist in the face of changing precipitation inputs, however, will depend less on seasonal redistribution than on the magnitude of reductions and changes in rainfall frequency.

Culture and Density Effects on Tree Quality in Midrotation Non-Thinned Loblolly Pine Plantations

Six non-thinned loblolly pine (Pinus taeda L.) culture × density study sites in the Piedmont and Upper Coastal Plain of the Southeast U.S. were used to examine the effects of two cultural intensities and three planting densities on solid wood potential as well as the proportion and position of product-defining defects (forks, crooks, broken tops). A tree quality index (TQI) was used to grade stems for solid wood potential. The results show that an operational management regime exhibited a higher proportion of trees with solid wood product potential than did a very intensive management regime. Trees subject to operational management exhibited product-defining defects higher on the stem; however, the proportion of stems with defects was not significantly different from the intensive management. Planting densities of 741, 1482, and 2223 trees per hectare (TPH) exhibited a relatively narrow range of the proportion of trees with solid wood product potential that were not significantly different. Density did not have a significant effect on the heights of the product-defining defects. These results show that management intensity and less so planting density, affect the solid wood product potential indicators evaluated and should be considered when making management decisions.

Fertilization increased leaf water use efficiency and growth of Pinus taeda subjected to five years of throughfall reduction

High productivity of fertilized loblolly pine (Pinus taeda L.) plantations in the southern United States is related to increased leaf area index (LAI), but higher evaporative leaf surface area may increase drought vulnerability. To determine if the benefits of fertilization are affected by water availability or the effects of drought are exacerbated by fertilization, the interactive effects of throughfall treatment (ambient throughfall versus throughfall reduction) and fertilization treatment (no fertilization versus one-time fertilization) on a loblolly pine plantation were examined over five growing seasons. Enhancement of LAI and growth from fertilization was unaffected by throughfall treatment, and reductions in LAI, tree height, and stand volume increment in response to throughfall reduction were unaffected by fertilization treatment. Leaf-level stomatal conductance (gS) was decreased and water use efficiency was increased by fertilization and by throughfall reduction. Lower gS was associated with decreased leaf predawn water potential in response to throughfall reduction. In contrast, lower gs in response to fertilization was associated with a reduction in the hydraulic allometry index, a measure of the ability of sapwood to supply water to leaves. These results suggest that fertilization may enhance LAI and growth even under mild or moderate drought.

Density reduction in loblolly pine (Pinus taeda L.) stands to increase tree C assimilation: an approach with the dual δ13C and δ18O isotope signatures in needles

In the context of increasing droughts related to climate change, our results showed that heavy thinning and/or very low initial planting density can increase CO 2 assimilation rate in needles, and may be used as a short-term management strategy for loblolly pine plantation across sites prone to drought. The dry summer of 2013 provided us an opportunity to understand the CO2 assimilation rate and stomatal conductance after density manipulation treatments using the dual isotope (δ13C and δ18O) signatures in needles of planted loblolly pine (Pinus taeda L.) trees in the southeastern USA. To our knowledge, this is the first study using the dual isotope approach to examine the physiological response of loblolly pine trees, one of the most widely planted tree species in the world, to stand density manipulation treatments (i.e., thinning intensity and planting density). In 2001–2003, trees were planted with five different planting densities, 494, 1111, 1729, 2346, and 2964 trees ha−1 at three sites. In 2009–2011, two thinning treatments (none and moderate thinning) were applied in the 1111 trees ha−1 plots, whereas three treatments (none, light and heavy thinning) were applied in the 1729 trees ha−1 plots. Response variables (specific leaf area (SLA), foliar N, δ13C and δ18O) were measured in February 2014. SLA was lower, while δ18O was higher in the 494 trees ha−1 plots than the 2964 trees ha−1 plots without thinning. In plots planted to 1729 trees ha−1 SLA was lower, while δ13C and δ18O were higher following heavy thinning than in the unthinned control. These responses plus increased crown length, DBH, and height following heavy thinning may reflect an increased tree-level CO2 assimilation rate. Our results showed that heavy thinning and/or very low initial planting density can be used as a short-term management strategy for loblolly pine plantation across sites prone to drought.

Economic feasibility of and vegetation responses to biomass harvest in managed loblolly pine plantations

ABSTRACTWe evaluated two biomass harvest methods, (1) Whole Tree Thinning (WTT; third-row thinning), and (2) Whole Tree Thinning with Fuelchips (WTTF; third-row thinning plus remove all accessible hardwood stems >2.5 cm diameter at breast height and understory shrubs in thinned area of stand) in a 21-year-old loblolly pine (Pinus taeda L.) plantation in northwest Florida for their harvesting yields and productivities, costs, and effects on groundcover. Both WTT and WTTF produced similar quantities of roundwood (~70 Mg ha−1) and chips (8.43–13.12 Mg ha−1) without significantly added operational time (15.77–28.12 Mg h−1). On-board costs of chip production (US$6.93 to 10.60 Mg−1) and total cost of roundwood and chip production (~22.5 US$ Mg−1) of the two harvest methods also did not differ significantly. Following either WTT or WTTF, overall percent groundcover recovered within 6 months. While shrub and grass cover were similar, forb cover in WTT increased significantly following six months of harvests. Importantly, the study suggests that biomass removal is an attractive option that could be integrated with traditional silvicultural thinning methods to manage vegetation and alleviate hazardous fuel and wildfire conditions, leading to improved forest health.

Bird response to intercropping switchgrass within a loblolly pine plantation

ABSTRACTGlobal interest in alternative, renewable energy sources has led to the development of novel land‐use practices and techniques aimed at maximizing energy production while also minimizing environmental, economic, and societal costs. One such novel practice is intercropping switchgrass (Panicum virgatum) within loblolly pine (Pinus taeda) plantations. However, minimal knowledge currently exists regarding the influence of intercropping switchgrass on ecosystem functions and services and biological diversity of loblolly pine plantations. Therefore, we assessed the influence of intercropping switchgrass on breeding‐bird species density and community composition during 2014–2015 in Mississippi, USA. We had 3,619 detections encompassing 39 species, with 10 species used in density analysis. Breeding‐bird density estimates did not significantly differ for 8 out the 10 species modeled between control and intercrop treatments. However, white‐eyed vireo (Vireo griseus) and indigo bunting (Passerina cyanea) densities differed between intercrop and control, with white‐eyed vireos having a greater density on control and indigo buntings having a greater density on intercrop. Treatment influenced breeding‐bird community composition, with monocultures supporting an atypical species composition within a loblolly pine plantation, but species composition did not differ between control and intercrop treatments. © 2017 The Wildlife Society.

An improved method for measuring the production, mortality and decomposition of extramatrical mycelia of ectomycorrhizal fungi in forests

The production and mortality of extramatrical mycelia (EMM) of ectomycorrhizal fungi are poorly quantified despite their importance in soil carbon cycling in forests. Ingrowth bag/core methods are the most widely used but can not accurately assess temporal changes in EMM production and mortality, resulting in great uncertainty in annual estimates. A modified method using two mathematical models (Biomarker and Algebraic models) is proposed to quantify EMM production, mortality and decomposition over differing time periods by integrating EMM decomposition dynamics with ingrowth core/bag data. In the Biomarker model, EMM biomass and EMM total mass (sum of necromass and biomass) are assumed to be known by using chemical biomarkers as proxies. In the Algebraic model, only the total mass is known and the biomass is calculated using an algebraic method. Model application in a loblolly pine plantation showed that mean monthly EMM production, mortality and decomposition estimates among three time periods ranged from 10.1 to 16.0 kg ha−1, 6.6–15.0 kg ha−1, and 1.4–6.1 kg ha−1, respectively, when using the Biomarker model, while these estimates ranged from 24.8 to 35.7 kg ha−1, 15.5–22.8 kg ha−1, and 5.7–9.8 kg ha−1, respectively, when using the Algebraic model, demonstrating the importance of assessing temporal changes. Model validation indicated that EMM estimates were more reliable for short-term compared to long-term incubation (184 vs. 322 days). Our method could improve EMM estimation by accurately assessing temporal changes in EMM production, mortality and decomposition in forests.