Effects Of Site Preparation Research Articles

The effects of shelterwood density and site preparation on natural regeneration of Fagus sylvatica in southern Sweden

The natural regeneration of beech ( Fagus sylvatica) was studied under various shelterwood densities and soil preparations in a 130-year-old beech stand in southern Sweden. Between 1990 and 1996, seedling emergence, survival, growth and damage were followed in a clear-cut and in two shelterwoods with different densities, in plots with undisturbed ground, bare mineral soil or ridges with mineral soil on top of humus. Irradiation, soil and air temperatures, soil moisture and precipitation were continuously recorded during the first three growing seasons. The seedling emergence was higher in the shelterwoods than in the clear-cut. The mortality was the highest during the first year. The seedling number was the highest on bare mineral soil and the lowest on undisturbed ground, for all cutting regimes. The increase in seedling height and dry mass was greater in the clear-cut and in the sparse shelterwood than in the dense shelterwood. Damage due to frost was more frequent in the clear-cut than in the shelterwoods. Effects of most kind of damage had only minor influence on the seedling height, whereas in seedlings experiencing frequent damage height was reduced.

Short- and long-term effects of site preparation, fertilization and vegetation control on growth and stand development of planted loblolly pine

Short- and long-term effects of high and low site preparation intensity, fertilization at planting and vegetation control on growth and stand development were examined in a study that was established on six sites in southeastern USA. The study was established in 1979–1980, and growth after the 18th growing season is reported. The high-intensive site preparation improved long-term stand volume growth. Evidence suggests that the main long-term effect of the intensive site preparation was a reduction in competition from hardwoods. Herbicide treatment improved seedling establishment and early growth, but growth during the last period of measurements (14–18 years after planting) were lower in the herbicide-treated plots as compared to plots without herbicide treatment when herbicides were combined with intensive site preparation. Fertilization at planting, in combination with high-intensive site preparation, improved volume growth during the first 10 years after planting, while fertilization at planting in combination with low-intensive site preparation had little effect on volume growth. The hypothesis that low variability in the seedling stage due to intensive site preparation will lead to low variability in the mature stands with a subsequent reduction in self-thinning was examined. The low site preparation intensity had higher coefficient of variations of stem volumes, and higher mortality. However, the difference in mortality was probably partly a result of differences in competition from hardwoods, and it was not possible to separate the importance of reduced variability from reduced competition from hardwoods. Fertilized plots had lower variability than non-treated control plots but there was no significant difference in mortality between the two treatments. Therefore, it was concluded that reduced variability in the seedling stands, as a result of intensive regeneration methods that reduces environmental heterogeneity, reduces the variability in the mature stands. However, it could not be inconclusively proved that lower variability in the mature stands will result in reduced or postponed self-thinning.

In-Situ Phytoremediation of TNT-Contaminated Soil

Parts of the area of the derelict World-War-II ordnance plant Werk Tanne (Clausthal-Zellerfeld, Harz, Germany) are heavily contaminated by chemicals resulting from TNT production and particularly by TNT itself. High soil contamination has to be treated with ex-situ methods but for the extended contamination of surface soil, in-situ phytoremediation is appropriate. The TNT-degrading potential of the rhizosphere of the planted trees and shrubs themselves is augmented by highly active mycorrhiza and white-rot fungi. A phytoremediation measure was established to scale with heavy machinery (soil grader), including the incorporation of white-rot fungi into the soil and planting of mycorrhized trees and shrubs. The effects of site preparation, mycorrhized rhizosphere and white-rot fungi on the degradation of TNT were assessed over one year using a complex monitoring scheme, including a battery of five biotests and field investigations of selected indicators (soil mesofauna, decomposition). The results of the monitoring showed the great influence of the grading procedure for site preparation, a diversified sensitivity of the biotest battery and complex reactions of the field indicators. The grading procedure effectively reduced the contamination (almost 90% within the first six months regardless of the initial levels). The phytoremediation measure as a whole reduced hazards of transport of nitro-aromatics by dust or leachate, initiated a secondary succession of the soil ecosystem that could transform the remaining TNT and metabolites over a longer period of time, and thus proved to be an effective decontamination measure applicable in large-scale technology.

Natural regeneration of Norway spruce, Scots pine and birch under Norway spruce shelterwoods of varying densities on a mesic-dry site in southern Sweden

The effects of shelterwood density and site preparation on the emergence, survival and growth of naturally regenerated Norway spruce ( Picea abies L. Karst.), Scots pine ( Pinus sylvestris L.) and birch ( Betula pendula Roth and B. pubescens Ehrh.) seedlings were investigated in Norway spruce shelterwoods in southern Sweden over a 6 year period. The shelterwood densities ranged from 277 to 96 stems/ha and an adjacent clear-cut. Scarification increased the emergence of all species. Increased shelterwood density promoted the emergence of Norway spruce seedlings, while the emergence of Scots pine and birch seedlings were not significantly affected by the shelterwood density. The survival of birch was negatively correlated to increased shelterwood density, while the survival of Norway spruce and Scots pine were less affected. Soil scarification had no significant effect on the survival of Scots pine and birch. In Norway spruce, the survival was higher in mineral soil than in undisturbed soil. Seedling growth decreased with increased shelterwood density for all species. Removal cutting of shelterwoods produced a high mortality in Norway spruce and Scots pine, but not in birch. The Norway spruce seedlings were evenly distributed throughout the shelterwood, whereas Scots pine and birch seedlings appeared in patches. Findings from this study indicate that a mixed-species forest may be established by using the following natural regeneration method: a sparse shelterwood, combined with scarification. Then, the future tree species mixture can be controlled through pre-commercial thinning and, if necessary, by complementary planting.

Effects of site preparation on runoff, erosion, and nutrient losses from Pinus plantations established on the coastal lowlands of south-east Queensland, Australia

Site preparation practices used during establishment of second rotation Pinus plantations on the coastal lowlands of south-east Queensland became more conservative during the 1990s. Traditionally, site preparation included stick raking of residue into windrows, followed by burning. Areas subject to periodic saturation were then cultivated to form continuous high mounds, while better drained sites were contour strip cultivated. These practices were replaced by retention of residue biomass on hillslopes. Similarly, intensive site disturbance was increasingly replaced by tillage of the immediate planting zone only and, as far as possible, avoidance of continuous furrows, major drainage structures, and high mounding works. In the study reported here, simulated rainfall and overland flows were used to assess the impacts of the earlier, less-conservative site preparation practices on hillslope soil loss, nutrient loss, and the potential for off-site nutrient movement.Where residue from clearfell harvesting of the first rotation was not removed, runoff, erosion, and nutrient loss were negligible. Harvesting tended to distribute residue widely across hillslopes, and, together with naturally occurring understorey biomass, it formed a largely continuous groundcover. Highest concentrations of sediment in overland flow were recorded for hillslopes in the newly stick-raked condition. Sediment concentrations in overland flows applied to properly designed and constructed high mounds were low, even for large flows simulating relatively long furrow lengths. However, sediment in rainfall-induced runoff from mounded areas was observed to be nutrient enriched, indicating potential for an off-site nutrient pollution risk, at least prior to establishment of grass cover along furrows. Nutrient enrichment was correlated with enrichment of finer size classes of sediment in runoff.The work reported in this paper vindicated the move away from traditional residue removal and site preparation practices to an approach based on residue retention, minimum site disturbance, and, wherever possible, ‘spot’ rather than continuous mounding/cultivation.

Are forest floors in mid-rotation stands of loblolly pine (Pinus taeda) a sink for nitrogen and phosphorus?

We examined decomposition and nutrient dynamics in fresh litter and net N mineralization in old litter to determine (i) if forest floor is a source of available nutrients in mid-rotation loblolly pine (Pinus taeda L.) stands and (ii) the effect of site preparation and vegetation control on forest floor nutrient dynamics. Four types of fresh litter were decomposed in situ in mesh bags: two containing only pine (differing by history of stand management) and two pine–hardwood mixes (ratios 1:5 and 5:1). Litter bags were recovered every May and October for 26 months. Litter type, in particular the presence and amount of leaves, affected decomposition and nutrient dynamics in fresh litter. After 26 months, all fresh litters lost 55% of mass; decay rate constants were 0.43 (needles) to 0.60 year–1 (leaves). Pine (1) and pine (2) and needles in mix 1:5 immobilized N. Almost all fresh litters also immobilized P. After 26 months of decay, N and P pools suggested an accumulation in the needles of 0.7–2.7 kg N·ha–1 and 0.2–0.5 kg P·ha–1 and mineralization of 1.1–3.7 kg N·ha–1 in mix 5:1 needles and mix 1:5 leaves. All fresh litters mineralized K, Ca, and Mg. Old litter was incubated in situ in capped polyvinyl chloride containers from May to November. Monthly rates of net N mineralization in old litter were determined in KCl extracts of NH4+ and NO3–. Net N mineralization in old litter was 0.75–1.5 kg N·ha–1 per 6 months and was attributed to mineralization in mineral soil. We conclude that forest floors in these stands are not a source of available N or P. Instead, forest floors appear to be sinks for N and probably P.

Vegetation management and site preparation effects on 13C isotopic composition in planted white spruce

Moisture availability is the factor that most commonly influences the discrimination against 13C fixation (Δ) by C3 plants. Therefore, by changing the availability of moisture by way of controlling competing vegetation, Δ in white spruce (Picea glauca (Moench) Voss) seedlings should be affected. The objective of this study was to determine the influence of manual brushing on Δ in white spruce seedlings planted in disc-trenched and control (i.e., no site preparation) microsites. The effects of site preparation and vegetation management on soil moisture, photosynthetically active radiation (PAR), and Δ in white spruce seedlings were evaluated over three growing seasons. Vegetation management increased the amount of PAR reaching seedlings in the control and disc-trenched treatments by removing the shading by native vegetation around each seedling. It appears that the increase in PAR reaching seedlings decreased Δ by increasing the photosynthetic consumption of CO2. Differences in soil available moisture (up to 22%) between control and disc-trenched treatments were not reflected in Δ values, contrary to our initial hypothesis. This may indicate that the site was not moisture limiting. Also, these results underline the complexity and difficulty of determining the controlling mechanisms by which Δ is affected.

Vegetation management and site preparation effects on <sup>13</sup>C isotopic composition in planted white spruce

Vegetation management and site preparation effects on <sup>13</sup>C isotopic composition in planted white spruce

Short-term Effects of Harvest Technique and Mechanical Site Preparation on Arthropod Communities in Jack Pine Plantations

Arthropods play a key role in the functioning of forest ecosystems and contribute to biological diversity. However, the influence of current silvicultural practices on arthropod communities is little known in jack pine (Pinus banksiana) forests, a forest type comprising a major portion of the Canadian boreal forest. In this study, the effects of silvicultural treatments on arthropod communities were compared to identify those treatments that minimize ecological impacts on arthropods. The influence of harvesting techniques and mechanical site preparations on insect family richness and abundance of arthropods (total, by orders and by trophic groups) was examined in young (three-year-old) jack pine plantations of northern Ontario. Each of the following treatments were conducted in three plots: (1) tree length harvest and trenching; (2) full tree harvest and trenching; (3) full tree harvest and blading; and (4) full tree harvest and no site preparation. Arthropods were collected using sweepnets and pitfall traps over two years. Blading significantly reduced insect family richness, the total abundance of arthropods, abundance of Orthoptera, Heteroptera, Hymenoptera, Diptera, insect larvae, and plant feeders when compared to the other treatments. The use of either full tree or tree length harvesting had similar short-term effects on family richness and the abundance of arthropods. Arthropod diversity declined with increasing post-harvest site disturbance. These results suggest that arthropod communities in the understory and on the ground are reduced most on sites mechanically prepared by blading, but are similar under conditions immediately following either full tree or tree length harvesting. The implications for regenerating jack pine in the boreal forest are discussed.

Nutrient availability and regeneration response after partial cutting and site preparation in eastern white pine

A 27-ha field experiment was set-up to study the effects of thinning, site preparation and underplanting in three 110-year-old natural eastern white pine ( Pinus strobus L.) stands using a four replicate, randomized block design. Three thinning and four site preparation treatments were applied. White pine seedlings were underplanted in sub-plots. Three years after treatment, a sample of natural and planted white pine seedlings was harvested to characterize growth and nutrient uptake. Ion exchange resin bags were used to assess soil nutrient availability. Light (PAR), soil moisture and soil temperature were assessed throughout the growing season. Nutrient availability was lower in the third as compared to the second growing season after treatment. Generally, environmental conditions improved and nutrient uptake and seedling growth increased after the silvicultural treatments were applied. Early white pine seedling growth was greatest following thinning of the overstory to a two-crown spacing, together with scarification and brush control.

Effect of site preparation on soil properties and vegetation cover, and the growth and survival of white spruce ( Picea glauca) seedlings, in Saskatchewan

A clear-cut aspen stand, near Prince Albert, Saskatchewan, was treated in July 1994 to encourage the establishment of mixed aspen-white spruce forest. Site preparation methods included use of a v-blade, disc trencher and Bracke mounder, as well as a drum chopper in combination with the disc trencher and Bracke. The study site was planted to white spruce in May 1995 using 3 + 0 nursery stock. During 1995 and 1996, soil and atmospheric conditions were monitored along with density and composition of regrowth vegetation and survival and growth rates of the white spruce seedlings. Although conditions for seedling establishment did not differ substantially between any of the treatments, the two drum chopper combinations were the most favourable. Both produced moderate height and biomass increases and low mortality rates, at the same time reducing competing aspen and shrub growth. The v-blade treatment also restricted encroachment of competing plants, and because of its lower cost makes it the preferred treatment method to establish a mixed aspen-white spruce forest stand.

Site preparation effects on foliar N and P use, retranslocation, and transfer to litter in 15-years old Pinus taeda

Intensive site preparation in loblolly pine ( Pinus taeda L.) plantations may remove nutrients and lower site productivity. We evaluated the effects of nutrient removal in site preparation on mid-rotation pine foliar production, and foliar N- and P-use, retranslocation, and transfer to litter for two years. We also investigated changes in foliar nutrients one year after fertilization. Site preparation treatments were: shear–pile–disk and chop–burn, used with or without vegetation control. Mid-rotation pines were fertilized with 200 kg ha −1 N and 50 kg ha −1 P, or with 200 kg ha −1 N and 50 kg ha −1 P and micronutrients. Foliar production was estimated from litter mass. N- and P-use was estimated from N and P concentrations in green foliage and foliar production. Retranslocation was the difference in N and P between green foliage and litter, in percent. N and P transfer to litter was estimated from litter N and P concentration and litter mass. Nutrient removal in site preparation at plantation establishment did not affect mid-rotation pine foliar production, foliar N- and P-use, retranslocation, or nutrient transfer to litter. The lack of site preparation effects may be related to the length of time after treatment; the stage of decomposition of organic matter that may be removed in site preparation may determine when nutrient supply will be affected. Competition with hardwoods decreased pine foliar production by 56%, and N- and P-use by 55% and 52%, but not percent retranslocation. On shear–pile–disk/herbicide, shear–pile–disk/no-herbicide, and chop–burn/herbicide plots (none or small hardwood component), average pine foliar production was 4365 kg ha −1 year −1, N- and P-use was 53.2 and 4.5 kg ha −1 year −1, N and P retranslocation was 63.7% and 69.8%, N and P transfer to litter was 18.9 and 1.3 kg ha −1 year −1. Based on a hypothetical N budget for the total stand, an N limitation may develop on those treatments that lost more nutrients in site preparation. Fertilization increased foliage production by 26%, and N- and P-use both by 49%, indicating some luxury consumption.

Effect of Site Preparation and Reforestation Method on Survival and Height Growth of Scots Pine

The influence of site preparation and reforestation method on the performance of Scots pine (Pinus sylvestris L.) was followed during 16 growing seasons in northern Finland using a split-plot design in randomized blocks. The site-preparation methods were prescribed burning (BURN), patch scarification (PATCH), disk trenching (DISK) and ploughing (PLOU). The reforestation methods were sowing (SOW) and planting with containerized seedlings (CON) and bare-rooted transplants (BARE). The reforestation was repeated in three successive years. A total of 72000 reforestation spots was sown or planted on the 288 plots using the reforestation density of 2500 spots ha –1. Four of the eight clear-cut forest sites were dryish pine-dominated sites and four were moist, formerly Norway spruce-dominated sites. After 16 growing seasons, average survival was 49% on the pine sites and 33% on the spruce sites. Site preparation significantly affected survival on the spruce sites (PLOU 44%>DISK 23%) but not on the pine sites. The reforestation method had a significant effect only on the pine sites (CON 58%)>SOW 36%). The effect of site preparation on mean height was significant on the pine (BURN 271 cm>DISK 222 cm) and spruce sites (PLOU 269, BURN 256 cm>DISK 212 cm). The differences between the reforestation methods were highly significant on the pine (BARE 295 cm>CON 261 cm>SOW 186 cm) and spruce sites (BARE 309 cm>CON 255 cm>SOW 171 cm). The results of this study indicate that different site-preparation methods can be used successfully in Scots pine reforestation on dryish, formerly pine-dominated sites in northern Finland. Intensive site-preparation methods, such as ploughing or mounding, are needed if Scots pine is to be established on moist, formerly spruce-dominated sites. However, the low survival and wide variation in survival indicated that there is a high risk of failure on such sites.

Effects of shelterwood and site preparation on microclimate and establishment of white spruce seedlings in a boreal mixedwood forest

Microclimate and seedling response of planted white spruce were investigated under four canopy densities (control – a 120-year old uncut aspen/white spruce stand, low and high residual densities of shelterwood canopy, and clearcut) and three site preparation treatments in the Lower Foothills of central Alberta. The partial canopy of the shelterwoods had a less extreme environment than the clearcut: higher humidity and soil temperature, lower maximum air temperature and occurrence and severity of night frost, and a light regime that was nearly optimum for height growth of juvenile white spruce. Planted white spruce seedlings had earlier bud break, lower seedling mortality and terminal bud mortality, higher rates of photosynthesis and stomatal conductance, and greater height and diameter increments under shelterwoods than those in either clearcut or control. Site preparation increased soil temperature, decreased seedling mortality and improved growth, especially diameter growth. This study demonstrates how shelterwoods and site preparation can improve the establishment of white spruce. The findings of this study can be applied to the situations where white spruce establishes in the understory. Key words: shelterwood, site preparation, white spruce, seedling response, microclimatic conditions.

Nitrogen Mineralization in a Pine Plantation Fifteen Years After Harvesting and Site Preparation

Intensive site preparation for forest tree planting may result in a mid‐rotation decline in soil N availability. Such decline has not been fully documented. This study was conducted in a loblolly pine (Pinus taeda L.) plantation in the Piedmont of North Carolina to evaluate the effects of nutrient removal during harvest and site preparation on N availability at mid‐rotation. Treatments, installed in 1981, consisted of a combination of harvest (stem‐only vs. whole‐tree) and site preparation (chop and burn vs. shear, pile, and disk), with a split‐plot of vegetation control (no herbicide vs. herbicide). In 1995 net N mineralization was examined by monthly in situ soil incubations from May through November (7 mo). Net N mineralization was approximately 3 times lower at mid‐rotation than shortly after treatment. A 5°C drop in soil temperature at 10‐cm depth helped explain ≈50% of this decline. At mid‐rotation, harvest intensity, but not site preparation intensity, affected N mineralization, with stem‐only harvest plots mineralizing 11 kg N ha−1 more than whole‐tree harvest plots during the seven months. Chop–burn–no herbicide plots mineralized 34(±3) kg N ha−1, chop–burn–herbicide: 30(±3) kg N ha−1, shear–pile–disk–herbicide: 28(±3) kg N ha−1, and shear–pile–disk–no herbicide: 19(±3) kg N ha−1 in the seven months. Mid‐rotation mineralization was positively correlated with soil temperature and negatively correlated with soil P and soil C:N ratio. The effect of harvest on N mineralization was probably exerted through P nutrition, whereas the lack of site preparation effects suggested that large nutrient removals that occurred with shearing and piling did not have lasting and negative effects on N availability in this plantation.

019 Hybrid Poplar Establishment in Tilled Ground or Grass Sod Using Polyethylene Films for Weed Control

Hybrid poplar is traditionally established using dormant stem cuttings in tilled soils followed by chemical or mechanical weed control. In 1996, we initiated a study to evaluate the effects of site preparation and four weed control treatments on growth and morphology of three hybrid poplar clones established on a 0.2-ha tall fescue field in southern Illinois. Site preparation included application of 2000 kg/ha of 12N-12P-12K. The experiment was arranged as a split-split plot. Main plots were closely mowed tall fescue or tilled to remove the grass sod. Within each main plot, weed control treatments were applied to 1-m wide strips in rows 2.4 m apart. Weed control treatments included porous black film, solid black film, and solid white film, and a control treatment of 3.7 L/ha of glyphosate applied each spring. On 15 Apr. 1996, three 25-cm-long dormant stem cuttings from each of three clones were randomly planted 15 cm deep every 1.8 m within each row. Clonal differences existed after the first year for survival, number of stems, stem height, stem basal diameter, and stem volume, but not for number and total length of lateral branches. Nearly all tree growth measurements analyzed during the first 3 years had a highly significant interaction between type of site preparation and method of weed control. With polyethylene films, tree survival exceeded 90% on both the tilled ground and grass sod sites after 3 years; however, with the herbicide treatment survival averaged only 18% in the grass sod and 51% in tilled soil. Excluding the herbicide treatment, tree growth was better in the grass sod than in the tilled soil. Tree growth using porous black polyethylene film was usually less than that with either of the two solid polyethylene films. The best tree growth was found with a grass sod and solid white polyethylene film for weed control.

Effect of Site Preparation and Reforestation Method on Survival and Height Growth of Scots Pine

Abstract The influence of site preparation and reforestation method on the performance of Scots pine (Pinus sylvestris L.) was followed during 16 growing seasons in northern Finland using a split-plot design in randomized blocks. The site-preparation methods were prescribed burning (BURN), patch scarification (PATCH), disk trenching (DISK) and ploughing (PLOU). The reforestation methods were sowing (SOW) and planting with containerized seedlings (CON) and bare-rooted transplants (BARE). The reforestation was repeated in three successive years. A total of 72000 reforestation spots was sown or planted on the 288 plots using the reforestation density of 2500 spots ha –1. Four of the eight clear-cut forest sites were dryish pine-dominated sites and four were moist, formerly Norway spruce-dominated sites. After 16 growing seasons, average survival was 49% on the pine sites and 33% on the spruce sites. Site preparation significantly affected survival on the spruce sites (PLOU 44%>DISK 23%) but not on the pine sites. The reforestation method had a significant effect only on the pine sites (CON 58%)>SOW 36%). The effect of site preparation on mean height was significant on the pine (BURN 271 cm>DISK 222 cm) and spruce sites (PLOU 269, BURN 256 cm>DISK 212 cm). The differences between the reforestation methods were highly significant on the pine (BARE 295 cm>CON 261 cm>SOW 186 cm) and spruce sites (BARE 309 cm>CON 255 cm>SOW 171 cm). The results of this study indicate that different site-preparation methods can be used successfully in Scots pine reforestation on dryish, formerly pine-dominated sites in northern Finland. Intensive site-preparation methods, such as ploughing or mounding, are needed if Scots pine is to be established on moist, formerly spruce-dominated sites. However, the low survival and wide variation in survival indicated that there is a high risk of failure on such sites.

Bedding and Fertilization Ameliorate Effects of Designated Wet-Weather Skid Trails after Four Years for Loblolly Pine (Pinus taeda) Plantations

Abstract Wet-weather harvesting operations on wet pine fiats can cause soil disturbances that may reduce long-term site productivity. Site preparation and fertilization are often recommended as ameliorative practices for such disturbances, but few studies have actually quantified their effects on restoration. The purposes of this study were to quantify the effects of wet-weather harvest traffic in designated skid trails on soil properties and loblolly pine (Pinus taeda) growth, and to evaluate the ameliorative effects of site preparation. Study sites were established on wet pine flats of the lower Coastal Plain within the Francis Marion National Forest (Berkeley County, SC). Treatments were arranged in a split-split plot within a randomized complete block design. Treatments were two levels of traffic (nontrafficked, trafficked), four levels of mechanical site preparation (none, disking, bedding, disking + bedding), and two levels of fertilization (none, 337 kg /ha of 10-10-10 fertilizer). initially, the trafficking increased soil bulk densities and reduced soil water movement and subsequent growth of loblolly pine (years 1 and 2). Bedding combined with fertilization restored site productivity to non trafficked levels within 4 yr, but disking or fertilization treatments alone were not effective at ameliorating the traffic effects. The effectiveness of the bedding and fertilization treatments for amelioration of traffic effects was probably facilitated by the relatively small area of disturbed skid trails (<10%) found on these sites. Areas having more severe disturbance or higher percentages of disturbance might not be ameliorated as rapidly. South. J. Appl. For. 22(4):222-226.

Effects of site preparation on timber and non-timber values of loblolly pine plantations

This study evaluated the timber and non-timber values of the forest stands generated by four site preparation methods tested in the Tuskegee National Forest 15 yr earlier. The timber values of the forest stands were assessed with the timber yields predicted by the SE TWIGS model. Non-timber benefits were evaluated through the Contingent Valuation Method. Two hundred residents randomly selected from three counties surrounding or near the National Forest were interviewed. The survey results indicate that the majority (62%) of the respondents felt that the National Forest should be managed for both timber and non-timber products. Of the four site preparation methods, the soil-active herbicide method was projected to produce the highest timber value. For non-timber benefits, the respondents preferred the forest stand without site preparation to those generated using chainsaw felling, soil-active herbicide, and tree injection methods. When both timber and non-timber values are considered, no site preparation is in general the best alternative that seems to meet the desires of the various groups of citizens with different or even conflicting preferences over timber and non-timber products.

Effect of site preparation on the nutrient content of non-crop vegetation in a jack pine clear-cut

The nutrient (N, P, K, Mg, and Ca) content of the aboveground living non-crop vegetation of a jack pine (Pinus banksiana Lamb.) clear-cut in eastern Ontario was investigated for two years after site preparation, which consisted of prescribed burning under different fire intensities and disk trencher scarification. Total plant nutrient content generally followed biomass accumulation with higher levels of plant N, P, Ca, and K in clear-cuts and scarified sites than in burned-over sites. In the first growing season, concentrations of N, P, and K were higher in the vegetation of burned-over plots than in scarified and clear-cut plots. Mg concentrations were greater in burned-over and scarified plots than in the clear-cut plots. Ca concentrations did not differ among the treatments. Concentration of P and K and the total amount of N, P and K in aboveground non-crop vegetation were correlated well with fire intensity at the end of the first growing season whereas only K concentration and quantities were correlated to fire intensity within two years after treatment. Key words: prescribed burning; disk trenching scarification; fire; Pinus banksiana; nutrients