Reserve Trees Research Articles

Effects of dispersed and aggregated retention on epiphytic microarthropod assemblages: A northern hardwood forest case study

Epiphytic lichens and bryophytes provide important habitat for microarthropods, yet little work has documented epiphytic microarthropod assemblages. Further, the response of epiphytes and their associated microarthropod communities to varying levels of forest disturbance and cutting intensity are not well known. We conducted a case study to provide an initial community description of epiphyte-dwelling microarthropods in Adirondack northern hardwoods, and to assess potential for impacts of aggregated and dispersed patterns of reserve tree retention to these communities. In total, 79 families of microarthropods were identified in the 0.14 m2 of samples. Late summer average daily maximum temperatures were 3.2 °C higher in the shelterwood, and three years following treatments the per-unit area dry weight of the bole-associated bryophyte Neckera pennata was 34 % lower in the shelterwood. Microarthropod richness and density were distinctly greater in epiphyte substrates at the base of trees, and were reduced in the shelterwood. Several indicator taxa were identified within the basal bryophytes in the reserve treatment, and in both bryophytes the microarthropod assemblages were more homogenous in the shelterwood. A few mobile and heavily sclerotized taxa persisted in shelterwood substrates, especially in the lichens which lacked 3-dimensional structure. This case study revealed a diverse community of microarthropods in northern hardwood forests that were structured by epiphyte type, height on tree and, potentially, by canopy removal, and suggests conservation value of aggregated tree retention when applying even-age regeneration methods with respect to epiphytic bryophytes, lichens, and their associated invertebrates.

Natural Canopy Disturbance Patterns and Ecological Silviculture in the Alabama Fall Line Hills

Abstract As a natural disturbance-based approach to silviculture is increasingly embraced by forest managers, quantitative reference conditions of natural disturbance patterns are paramount. We used LiDAR data to quantify resultant structural patterns from an EF3 tornado on the Oakmulgee Ranger District of Talladega National Forest in the Alabama Fall Line Hills, USA. We found the zone of catastrophic disturbance totaled 123 ha, had a mean width of 360 m, and residual trees were randomly distributed. This zone was buffered by an edge zone of intermediate-severity disturbance where trees were removed individually and in groups. The edge zone averaged 220 m in width. In total, the study area included seventy-nine stands and the percentage of stand area damaged ranged from < 1% to 94%. We suggest that clearcut, seed tree, and shelterwood with reserves regeneration methods may be appropriate analogs to natural canopy disturbance in the Fall Line Hills region. These catastrophic disturbance entries should be buffered from undisturbed neighborhoods by a system that retains mature forest structures and would constitute a zone of intermediate-severity disturbance. Our approach may be used as a template to expand our understanding of natural canopy disturbance patterns in other regions and forest types. Study Implications: In regions where tornadoes are a natural component of the disturbance regime, including much of the southeastern United States, we suggest that clearcut, seed tree, or shelterwood with reserves regeneration methods may be used to approximate the zone of catastrophic disturbance that corresponds to the tornado track. We observed that reserve tree spatial patterns were random, but residual trees could be selected based on desired species or protection of important biophysical features such as seeps. Surrounding the catastrophic disturbance zone was an edge zone of intermediate-severity disturbance where trees were removed individually and in variably sized groups. We suggest that the structural patterns documented in this edge zone may be created through variable retention harvesting.

Silviculture in the function of sustainable development

Silviculture in the function of sustainable development

Proximity to riverbed influences physiological response of adult pedunculate oak trees

The pedunculate oak (Quercus robur L.) is economically and ecologically one of the most significant tree species in Serbia, however, little is known about the influence of the riverbed distance and its water supply on ecophysiological responses of this species. Given the limited information on the light-response curve of photosynthesis for oaks in southwest Srem, Serbia, the aim of this paper is to enhance understanding of their ecophysiological responses in this context. Maximum assimilation rate (Amax), the quantum yield (F), and light compensation point (LCP) were compared in adult trees situated along the transect from the river: (1) close to the river, (2) intermediate, (3) farthest from the river, and (4) forest reserve (second closest), with the first three transects being managed forests and the last one being an unmanaged forest reserve. The measurements were conducted in July during the first evidence of drought. The highest Amax rates were measured in all light intensities on the site closest to the river and the smallest on the site that was most distant to the water source. The most efficient were trees close to the river and the ones in the forest reserve. No significant difference between compensation points was confirmed for the studied groups of trees, although the forest reserve trees showed slightly higher values. The results demonstrated clear response between transects, which followed the distance from the riverbed. Pedunculate oak's reliance on groundwater is in tight relation with ecophysiological processes in trees; groundwater depletion may threaten its survival in areas distant from the river.

Effects of silvicultural selection treatments on spatial pattern and dynamics in a Pinus palustris Mill. woodland

Natural disturbance-based silviculture emphasizes harvest methods that emulate the timing and structural changes of natural disturbances. Longleaf pine woodlands are ecologically important ecosystems of the southeastern U.S. that support high biodiversity. Options for multi-aged silviculture include individual tree and group selection methods to promote regeneration—the latter method may be modified by retention of reserve trees. To explore the extent to which selection methods are congruent with natural disturbance regimes, we evaluated how treatments in mature second-growth longleaf pine woodlands affected overstory structure, pattern, and dynamics, and we made comparisons to an old-growth longleaf stand. In 2010, stands were harvested using individual tree selection, group selection, or group selection with reserves. We compared treatment effects on spatial pattern of residual trees, recruitment of trees into the 10 cm diameter class (hereafter “recruitment”), and tree mortality 8 years after harvest. Basal area and residual volume were similar among treatments, but the individual tree selection treatment had lower density and a unimodal rather than bimodal diameter distribution compared to other treatments. Group selection and group selection with reserves increased spatial aggregation, compared to individual tree selection which reduced aggregation. Recruitment was similar across treatments but usually occurred near existing trees in the group selection treatments and was further from existing trees in the individual tree selection treatment. Tree mortality primarily occurred as single trees rather than tree groups for all treatments. These results indicate that natural disturbance-based treatments vary in their effects on overstory spatial pattern and alter forest dynamics. In longleaf pine woodlands, the rationale for individual tree selection emphasizes maintaining a continuous input of needles as fine fuels for control of resprouting hardwoods with prescribed fire. This method, may simplify overstory spatial structure and alter forest dynamics after initial harvest. Maintenance of vertical and horizontal complexity is a central tenet of natural disturbance-based management, thus attention to spatial pattern must be given when individual tree selection methods are used. In longleaf pine woodlands, natural disturbance-based techniques such as group selection with reserves may better mimic spatial patterns seen in old-growth stands while preserving continuity of fine fuels.

EUCALYPTUS TREE COLONIZATION OF THE BAFUT-NGEMBA FOREST RESERVE, NORTH WEST REGION, CAMEROON

Recent environmentalism in Cameroon and forest reserve creation has been varied in implementation and management between community and national stakeholders and policies. Good national intents for hot spot conservation saw the 1953 creation of the Bafut-Ngemba production forest reserve on the Bamenda Highlands, where today’s accelerated urbanization and development has largely engulfed. Pressure on the forest reserve resources has thwarted its spatio-temporal natural tree cover climax. The study uses a field survey and secondary data treatment methodology to probe how communities at the reserve fringe have responded to unmet natural wood demands by pushing in eucalyptus tree plantations to result in forest reserve reversal. Varied income-driven circumstances generated an overwhelming embrace of a eucalyptus culture swallowing up the natural trees. A thirty-year evaluation of the tree cover revealed a near 40% loss the reserve trees while eucalyptus laden-farmland have been gained ascendancy. This ecological colonization scramble was timid in the 1980s, then rapid in the 1990s and then exponential by 2018. There is a direct relationship between this spatial gains from the eucalyptus and population growth demand trends. The study therefore opts for a quick revisit of the initial forest reserve philosophy that is now being diluted in this eucalyptus embrace. These eucalyptus trees are ecological terrorists that should never be permitted to terrorize production forest reserves.

Effects of multiaged silvicultural systems on reserve tree growth 19 years after establishment across multiple species in the Acadian forest in Maine, USA

This study investigated the growth response of mature, isolated reserve trees (n = 528) in two multiaged silvicultural systems in the Acadian Forest Ecosystem Research Project (AFERP). Absolute and percent increases in basal area increment (BAI; cm2·year−1) were assessed for the five predominant reserve tree species in AFERP: Acer rubrum L., Picea rubens Sarg., Pinus strobus L., Thuja occidentalis L., and Tsuga canadensis (L.) Carrière. Absolute growth was significantly greater in the large-gap treatment (23.7 ± 1.1 cm2·year−1; mean ± SE) than in the small-gap treatment (16.3 ± 0.9 cm2·year−1). Percent growth increase was greater in the small-gap treatment (187.6% ± 15.8%) than in the large-gap treatment (143.4% ± 19.3%), and both treatments had greater percent increases than the unharvested control (9.6% ± 5.2%). Species differed in their response to treatment. Pinus strobus had the greatest absolute increase (large-gap, 52.5 cm2·year−1), while Tsuga canadensis (large-gap, 270% ± 71.6%) and Acer rubrum (small-gap, 262% ± 42.4%) had the greatest percent increases. Growth responses typically diminished with increasing tree size and pretreatment growth rate; however, reserve trees showed greater growth responses than their paired analogues in the control across all initial tree sizes and prior growth rates. The results suggest that these silivicultural systems accelerate the development of large trees.

Reserve tree mortality in two expanding-gap silvicultural systems 20 years after establishment in the Acadian forest of Maine, USA

Land managers are increasingly called upon to maintain ecosystem function and restore late-successional forest structures by retaining trees (“reserves”) in harvest prescriptions. Such retention practices often result in mortality of reserve trees owing to increased exposure to wind and ‘gap shock’, thereby compromising management objectives. This study investigated the mortality of reserve trees (n=787) retained over 20years in the Acadian Forest Ecosystem Research Project (AFERP), a long-term ecological forestry experiment in central Maine, USA. Cumulative mortality across 18 species was very low (8.4%±3.3%, mean±SD) relative to similar studies throughout the world. Annualized mortality of reserve trees of the two silvicultural systems was 1.1% for the large-gap treatment and 0.4% for the small-gap treatment. Cumulative mortality of Tsuga canadensis was lowest (2%) among species with >50 individuals, while the cumulative mortality of Thuja occidentalis was highest at 19%. Over 59% of cumulative mortality was wind-related. Annualized wind-related mortality of the reserve trees was 0.6% in the large-gap treatment and 0.2% in the small-gap treatment. More vigorous trees showed lower mortality rates. Cumulative mortality and wind-related deaths were somewhat higher in large gaps, and were influenced by spatial position within gaps. The non-traditional, expanding-gap, multi-aged silvicultural systems in this study may explain the lower incidence of windthrow and gap shock experienced by reserve trees relative to the annualized mortality rates from studies of similar, though predominantly single-cohort, silvicultural systems.

Response of the soil microbial community and soil nutrient bioavailability to biomass harvesting and reserve tree retention in northern Minnesota aspen-dominated forests

Intensive forest biomass harvesting, or the removal of harvesting slash (woody debris from tree branches and tops) for use as biofuel, has the potential to negatively affect the soil microbial community (SMC) due to loss of carbon and nutrient inputs from the slash, alteration of the soil microclimate, and increased nutrient leaching. These effects could result in lowered forest productivity and threaten the long-term sustainability of forest management. Retaining organic material post-harvest, including greater amounts of harvesting slash and live trees, within harvested areas may ameliorate some negative effects of biomass harvesting on soil processes. We evaluated the effects of biomass harvests with reserve tree and slash retention on the SMC and soil nutrient bioavailability (assessed using plant-root simulator probes) in trembling aspen (Populus tremuloides Michx.) forests in northern Minnesota during the spring and summer, 1–3 years after harvest. Variable biomass removal levels tested include complete removal (whole tree harvest of boles and branches), complete slash retention (bole only harvest), and 20% slash retention (amount suggested by regional biomass harvesting guidelines). Compared to the unharvested control, biomass harvests had no effect on the multivariate SMC composition or microbial biomass, but did result in a 1–4% increase in arbuscular mycorrhizal fungal abundance and reduced bacterial stress two and three years after harvest. Additionally, biomass harvesting increased NH4 bioavailability during year one, and reduced NO3 bioavailability during year two when compared to unharvested controls. Among the three biomass harvests with differing levels of slash removal there were few differences in overall SMC composition, microbial biomass, and soil nutrients; however, the abundance of arbuscular mycorrhizal fungi, gram positive and actinomycete bacteria were significantly higher in harvested treatments with more slash retained. These results are specific to single rotation biomass harvesting in aspen stands due to the unique relationships between plants and their associated SMCs, and may not be directly applicable to forest biomass harvesting of other commercial forest tree species, or multiple rotations.

An Examination of the Condition of Young Natural Asian White Birch Trees in Manhanshan National Forest Park (Inner Mongolia, China) and Its Early Thinning Technology

The goal of the study was to demonstrate forest thinning techniques that should be used beginning in 2011 for the ultimate purpose of timber production by analyzing the stand structure of unthinned natural Asian White Birch forests aged 10-25 years in Manhanshan National Forest Park. The results of the study led to the following three observations: (1) among dominant trees, those with relatively good characteristics should be selected as reserve trees. Any trees obstructing the growth of the reserve trees must be removed as thinned trees. In addition, dominated trees which do not have an impact on the growth of reserve trees are left unthinned to prevent the occurrence of epicormic shoots in reserve trees. (2) The forest at 8-15 year-old should preferably be thinned for the first time. (3) It is desirable to implement thinning frequently at low intensity.

Snags and Cavity-Nesting Birds within Intensively Managed Pine Stands in Eastern North Carolina, USA

Abstract Although snags are often considered to be a limiting factor for cavity-nesting birds within intensively managed pine (Pinus spp.) stands, there is little information regarding occurrences of snags and cavity-nesting birds for such stands in the southeastern United States. Therefore, during 2002–2003, we measured characteristics of individual snags (n = 1,218) and quantified the relative abundance of cavity-nesting birds (n = 204 observations; nine species) in 35 forest stands representing seven thinning classes (prior to thinning, three age classes following a first commercial thinning, and three age classes following a second commercial thinning entry) in intensively managed pine stands in eastern North Carolina. Snag populations were dynamic, with 649 snags falling and 75 new snags recruited between years. Stands in later thinning classes tended to have snags with larger diameters, less bark, and fewer limbs, and they were taller and more decayed (P < 0.05). Our data suggest that neither density of snags (P = 0.31) nor relative abundance of cavity-nesting birds (P = 0.25) differed strongly among thinning classes. Without active management, low recruitment coupled with the high loss rates that we observed ould lead to low snag densities in older managed stands. Therefore, we suggest that forest managers consider retaining large-diameter dead or live trees as reserve trees through multiple rotations to increase or maintain snags in managed stands.

Viability of Northern Pin and White Oak Reserve Trees in Wisconsin Scrub Oak Sites

Abstract Retention of reserve trees can serve multiple objectives when harvests are conducted on scrub oak sites. The objective of the study was to determine the growth and vigor response of northern pin and white oak held as reserve trees from harvests occurring over a 15-year time period onscrub oak sites in Central Wisconsin. Reserve trees were evaluated for volume growth, epicormic branching, live crown ratio, and tree vigor. White oak maintained or improved in vigor and exhibited increased rates of volume growth with no measured mortality. Northern pin oak, although exhibitingincreased volume growth, tended to decline in vigor and experienced an overall annual mortality rate of 5.5%. For managers that are considering multiple objectives, white oak can provide a long-lived vigorous reserve tree while northern pin oak may survive but will experience decline and higherrates of mortality, which may contribute to a long-term goal of snag retention as an element of wildlife habitat.

Influence of individual reserve trees on nearby reproduction in two-aged Appalachian hardwood stands

In the 1970s, public opposition to clearcut harvesting in hardwood forests of the eastern United States led forest managers and scientists to consider alternative practices that retain a low-density overstory forest cover. From 1979 to 1984, a form of clearcut-with-reserves harvesting was applied in 80-year-old Appalachian mixed-hardwoods to create four experimental stands with two-aged structures. The residual stand basal area averaged 5.3 m 2/ha, comprising an average of 36 reserve trees/ha. The reserve trees were evenly distributed throughout the stand, initially with considerable space between their crowns, thus providing the sunlight and seedbed conditions needed to recruit desirable shade-intolerant reproduction after harvest. This study examined the response of the 100-year-old reserve trees and the development of the 20-year-old natural reproduction located in their immediate vicinity. Diameter at breast height (Dbh), height, and relative position were recorded for all reproduction ≥2.5 cm within transects adjacent to northern red oak ( Quercus rubra L.) and yellow-poplar ( Liriodendron tulipifera L.) reserve trees. Each transect was divided into five zones, which represented positions relative to the reserve tree crown edge, and basal area was computed for each of three shade tolerance classes within each zone. A repeated measures ANOVA was used to compare basal area of reproduction by tolerance classes and zone. In general, basal area of reproduction, particularly that of shade-intolerant species, increased with distance from the reserve tree. Regression analyses also indicated that dbh and height of reproduction was positively related to distance from the reserve trees. Although height growth of reserve trees was similar for both species, northern red oak exhibited significantly greater dbh and crown radial growth than yellow-poplar. The results indicated that reserve trees influence the growth rate and species composition of reproduction in their immediate vicinity. Basal area of reproduction increased from 10.1 to 17.7 m 2/ha with increasing distance from the reserve trees. Basal area of intolerant species more than doubled along the same gradient. Basal area of reproduction in the two-age stands was 30–40% less than that observed in even-aged stands on similar growing sites, but the reduction was offset by growth of the reserve trees. The surface area covered by the reserve tree crowns increased approximately 88% for northern red oak and 44% for yellow-poplar. Since the sphere of influence of reserve trees increases over time, forest managers must consider their long-term impact on reproduction when prescribing clearcut-with-reserves harvests and other practices that involve retaining trees for many years.

Spatial patterns of regeneration in managed uneven-aged ponderosa pine/Douglas-fir forests of Western Montana, USA

In uneven-aged ponderosa pine ( Pinus ponderosa Dougl.) and Douglas-fir ( Pseudotsuga menziesii var. glauca (Mirbel) Franco) stands managed by individual tree selection, the recruitment of new sapling cohorts necessary to sustain structure and composition is generally assumed to occur within canopy openings created by harvest. However, few studies have examined the spatial patterns of new regeneration in relation to reserve trees in the overstory in this forest type. In this study, we analyzed the spatial distributions and associations between saplings and overstory trees using univariate and bivariate transformations of Ripley's L-functions. Furthermore, we introduced a ratio-based index to quantify the strength of bivariate spatial associations, which allowed us to further evaluate potential causes for the observed patterns. We found that saplings of both ponderosa pine and Douglas-fir established predominantly in clumps, and that saplings of the two species generally had a positive association with one another at short scale (up to 5 m). We found no evidence to suggest that saplings of ponderosa pine and Douglas-fir occupied separate spatial locations in these stands. We also found mixed results for bivariate associations between saplings of both species and overstory trees, where both positive and negative spatial associations occurred depending on the putative moisture level of plots indicated by habitat type group. The strength of positive spatial association between saplings and medium-sized overstory trees appeared to decrease as plot moisture-level increased, suggesting that sapling establishment and survival might be facilitated by shading on moisture-limited sites.

Fate of Overstory Trees and Patterns of Regeneration 12 Years After Clearcutting with Reserve Trees in Southwest Washington

Abstract Changes in management objectives for some forestlands in the Pacific Northwest have spurred interest in the creation of multistoried stands and the use of natural regeneration systems, but data on such systems are lacking. We assessed the status of the overstory trees and the regeneration 12 yr after a clearcut harvest with reserve trees in an even-aged, 145-yr-old Douglas-fir stand on a moderately productive site (site class 3) in southwest Washington. The 15 ha harvest unit was superimposed over two areas differentially thinned 15 and 34 yr before clearcutting. The clearcut harvest retained 18 trees/ha with a mean diameter of 63 cm. The reserved overstory trees had a 93% survival rate after 12 yr; most dead trees had been windthrown. Diameter growth for the reserved trees averaged 3.3 cm and was greatest during the most recent 3 yr period, which also had the highest growing-season precipitation. In a 1 ha mapped area, there were 5,854 seedlings/ha, and more than 99% of the regeneration was Douglas-fir. Most seedlings were less than 2 m tall. Seedling density was somewhat clumped (value of 2.1 for Pielou's index of nonrandomness), but 79% of randomly located 4.04 m2 (mil-acre) plots and 98% of 5 × 5 m grid cells had at least one conifer seedling. There was no obvious pattern of regeneration based on direction from the reserved trees, but both seedling density and seedling size within the drip lines of reserved tree crowns were less than in the rest of the area. The number of seedlings was similar on the two halves of the plot corresponding to the original thinning blocks, but seedling size and age differed. In the half of the study plot that had been twice lightly thinned, only 14% of the seedlings were >0.5 m tall; however, 41% of the seedlings were >0.5 m in the block that had been thinned more heavily. There was no difference between the thinning blocks in the ages of seedlings ≤0.5 m tall (mean age of 5 yr). This example of clearcutting with reserve trees resulted in reasonable survival of the overstory trees and adequate stocking but slow growth rates in the naturally regenerated Douglas-fir. Heavier thinning before harvest was associated with more advance regeneration, more shrub cover, and less windthrow of the reserved trees than in the more lightly thinned block. If an abundance of tree species other than Douglas-fir was desired on this site, interplanting would be required. West. J. Appl. For.17(2):78–85.

Rationale and methods for conserving biodiversity in plantation forests

Industrial forest managers and conservation biologists agree on at least two things: (1) plantation forests can play a role in conserving biodiversity, and (2) plantations will occupy an increasing proportion of future landscapes. I review literature from around the world on the relationship between biodiversity and plantation management, structure, and yield. The dynamics of plantation ecology and management necessarily differ by landscape, geographic area, ecosystem type, etc. This review provides a broad array of management recommendations, most of which apply to most regions, and many patterns are evident. I suggest a new plantation forest paradigm based on the hypothesis that minor improvements in design and management can better conserve biodiversity, often with little or no reduction in fiber production. There is ample evidence that these methods do benefit biodiversity, and can also entail various economic benefits. Adherence to these recommendations should vary by plantation type, and depending on the proportion of the surrounding landscape or region that is or will be planted. Stand-level variables to consider include socio-economic factors, native community type and structure, crop species composition, and pest dynamics. During establishment, managers should consider innovations in snag and reserve tree management (e.g. leave strips), where mature native trees and/or understory vegetation are left unharvested or allowed to regenerate. Polycultures should be favored over monocultures by planting multiple crop species and/or leaving some native trees unharvested. Native species should generally be favored over exotics. Site-preparation should favor methods that reflect natural disturbances and conserve coarse woody debris. Plantations that have already been established by traditional design can also conserve biodiversity via small modifications to operations. Earlier thinning schedules or longer rotations can strongly affect biodiversity, as can reserve trees left after plantation harvest to remain through a second rotation.

Biomass Flow in Western Forests: Simulating the Effects of Fuel Reduction and Presettlement Restoration Treatments

Abstract Fuel treatment silviculture and the resulting long-term flow of biomass were examined using data from selected western stands. An uneven-aged management regime with reserve trees was modeled, using a canopy closure of 40 percent for the dominant trees as a target and a harvest cutting cycle of 20 years. Fuel reduction treatments in currently overstocked stands resulted in an initial peak of removal for the first and second cutting cycles. Yields stabilized in subsequent cutting cycles. Removal of some large reserve trees was crucial for maintaining stand structure and fire resilience.

A General Equilibrium Analysis of the Economic Aspects of the Imposition of an Export Tax on the Plywood Sector in Indonesia

Computable general equilibrium (CGE) models are extensively used to simulate the economic impact of forest policies. In this study, we conduct a counterfactual analysis to assess the impact of an export tax ranging from 5 to 20% on the plywood sector to the Indonesian economy. The indonesian economy is aggregated into 5 sectors: 2 sectors are related to forest,i.e., (1) log, and (2) plywood. The other three sectors are not related to forest,i.e., (3) non-wood manufacturing, (4) agriculture, quarrying, and services, and (5) construction. The simulation results show that an export tax on the plywood processing sector is negatively correlated with real GDP and labor demand in log and plywood sectors, but is positively correlated with total labor demand, government revenue, income distribution, wood resources and social welfare. Reduction in labor demand by log and plywood sectors, due to a plywood export tax, can be absorbed in other sectors. The simulated policy of an export tax on plywood can reserve trees in production forests for future use.

Simulated conversion of unmanaged interior spruce-subalpine fir stands to a regulated uneven-aged structure

A localized version of the Forest Vegetation Simulator (FVS) individual tree growth model was developed to simulate stand level impacts under a variety of uneven-aged management regimes in old-growth interior spruce-subalpine fir forests near Prince George British Columbia. Options for using uneven-aged management to satisfy a range of management objectives were simulated using different sets of BDq regulation parameters, and by varying species composition and rules for reserve trees. The greatest timber yields were attained by promoting the highest possible spruce component, using high q ratios, low to moderate maximum diameters and 20 to 25 year cutting cycles, and allowing no reserves. Using strategies to promote stand structures maintaining some old-growth attributes resulted in much lower timber yields. Key words: white spruce, Engelmann spruce, subalpine fir, uneven-aged management, BDq regulation, simulated yield

Loblolly Pine Stand Early Development Under Reserve-Tree Silvicultural Systems in East Texas

Abstract Even-aged reproduction methods retaining reserve trees that persist through the development of the succeeding rotation have been poorly studied in loblolly pine (Pinus taeda L.), yet have potential for satisfying a variety of landowner objectives. Two research sites were established in the East Texas Pineywoods region to examine the development of the regeneration component under five residual basal area densities (0, 10, 20, and 40 ft2/ac with natural regeneration on Site I; 0 and 30 ft2/ac with both natural regeneration and planting on Site II). After 7 yr on Site I and 5 yr on Site II, all reserve-tree methods allowed the development of a sufficient number of trees for producing a new generation beneath the residual overstory. However, suppression of the understory pines was evident, and varied in direct proportion to the basal area of the residual overstory. Volume growth of the residual overstory trees was low on an areal basis due to the death of several large residuals. A trenching experiment showed that the largest effect of the residual overstory on understory development was due to light attenuation rather than competition for soil resources. Advantages offered by reserve-tree methods for loblolly pine have to be assessed in view of the suppressed development of the regeneration. South. J. Appl. For. 24(1):11-16.