Slash Treatments Research Articles

Mechanical site preparation in South Africa: comparing the productivity of pitting machine operators under different site conditions

ABSTRACT Pitting is the preparation of a tree planting position. In South Africa, various contractors and grower companies have gradually adopted pitting machines over the past decade, to overcome the challenges of manual pitting, such as low productivity, poor ergonomics, and inconsistent pit quality. Even though most forestry stakeholders understand productivity requirements (e.g. pits/shift) from pitting machines, they are often unaware of productivity differences associated with different operators and work conditions. This study aimed to compare the operational productivity and pit quality achieved by different pitting machine operators under different site conditions. The experiment was conducted in two sub-compartments, with two different post-harvest slash treatments: broadcast burning or mulching (and pre-marking). Then, four operators were tasked to dig pits using the same equipment. Operator productivity was assessed by analyzing time study data, while pit quality was estimated by determining pit depth and diameter. The results indicated that Operator 4 performed significantly better on mulched sites (543 pits/PMH) than on burned sites (430 pits/PMH), while Operator 2 was the least productive with 261 and 253 pits/PMH in mulched and burned sites, respectively. The overall average productivity was 120 pits/PMH higher on mulched sites than on burned sites. Although work quality did not correlate with productivity, there were differences between operators on the mulched site. The proportion of good pits varied, but site preparation technique did not significantly affect pit quality. We conclude that operator experience significantly impacts productivity and that marking the pitting spots is important to ensure that the required number of pits per hectare is achieved.

The impact of slash management, fertilisation and vegetation management on Pinus elliottii pulpwood growth and rotation-end yield

Intensive silviculture (re-establishment) is practised within South African plantations to increase the potential productivity per unit area. Rotation-end productivity benefits are not well documented to support intensive inputs. A trial investigating rotation-end (17 years) impacts of slash management (clear, single and double slash loads), fertilisation (fertiliser applied versus no fertiliser applied) and vegetation management (none versus continuous weeding) was implemented on Pinus elliottii grown in Mpumalanga, South Africa. Competitive vegetation cover abundance and biomass, soil and foliar nutrients, and tree survival, growth and uniformity were recorded. The biomass sampled indicated a relationship between slash management and fertilisation with the vegetation biomass highest within the treatments where slash was cleared in combination with fertiliser application (4 398.7 kg ha−1) and within double slash treatments in combination with no fertiliser application (4 698.0 kg ha−1). Of all the main factors, only vegetation management significantly improved tree survival and growth (height, Dbh, basal area and volume) at rotation-end. Vegetation management improved survival by 9.4%, resulting in 67.5 m3 ha−1 more volume than in treatments where no vegetation management was carried out post-planting. This trial has highlighted the importance of vegetation management on rotation-end P. elliottii productivity.

President's proposed budget would slash treatment and prevention funding

We had a feeling of déjà vu when the White House sent its proposed budget to Congress last week. Similar to past years, the Office of National Drug Control Policy (ONDCP) would be decimated, moving the $100 million Drug‐Free Communities program to the Center for Substance Abuse Prevention (CSAP) at the Substance Abuse and Mental Health Services Administration (SAMHSA). There's no additional money in the Substance Abuse Prevention and Treatment (SAPT) block grant and cuts to the National Institute on Drug Abuse, the National Institute on Alcohol Abuse and Alcoholism, CSAP and SAMHSA's Center for Substance Abuse Treatment.

Adding carbon at a standard and a higher rate reduces soil nitrate in a grassy woodland

SummaryC addition has been used successfully in grassland restoration in Australia, generally as sucrose at a standard rate of 840 g C/m2/year. Previous experiments that have varied the rate of soil carbon application to reduce nitrate to favour native over nitrophilous exotic species have found that the benefits can increase over the whole range used for some native species, but only appear above particular rates of C addition for others. A restoration trial of degraded grassy woodland on former agricultural land in western Sydney combined burning and slashing to remove biomass with C addition at the standard rate, and a high rate, to reduce soil nitrate on the burnt or slashed plots. Soil was sampled for extractable nitrate, ammonium and phosphorus, and plant root simulator probes were used to measure nitrate and ammonium supply. Both extractable nitrate and nitrate supply were periodically high in the controls, at which times C addition at the standard rate significantly reduced extractable nitrate with an even greater reduction at the high rate, and resulted in negative relationships between nitrate supply and added C. Effects of added C on extractable nitrate or nitrate supply were not detectable in non‐peak periods. Extractable ammonium and ammonium supply were either unaffected or increased with added C. Colwell phosphorus showed temporal variation but was unresponsive to added C. Of the three nutrients, only the decline in nitrate matched the decline in plant cover which was lowest in value at the high carbon rate (Morris & Gibson‐Roy 2018). In the absence of added C, extractable nitrate was less than control values in the fire and slash treatments 1 year after treatment application but was similar to control values at other times.

Comparison of biomass removal, nutrient manipulation and native seed addition to restore the ground layer of a degraded grassy woodland

This study reports on a trial of methods to overcome barriers to restoration of degraded Cumberland Plain woodland. Soil scalping was compared with fire or slashing to remove existing canopy. Fire and slashing were combined with soil carbon addition at two levels, to reduce soil nitrate. Native seed was added to overcome a lack of native propagules. Treatments, applied to 2 × 2 m plots, consisted of a control; scalped; fire and slash treatments without carbon addition; fire and slash treatments at the low and the high carbon addition levels; and a further fire and a slash treatment at the low carbon level with no native seed added, to give 10 treatments in total. Scalping eliminated the existing canopy and reduced weed seed and bud banks allowing native species (and some colonising exotics) to establish by 33 months. Rapid re-growth in the fire treatment resulted in plant canopy abundance returning to control levels by 12 months, and native species richness on burnt plots remained similar to the control. Canopy abundance in the slash treatment remained lower than in the controls for 20 months, and native species richness increased by then. Carbon addition reduced canopy re-growth in both fire and slash treatments: in the fire-low carbon plots with added native seed, native species richness was double that of the controls by 20 months. This increase did not occur on slash-low carbon plots. The highest level of carbon addition had negative effects on plant growth and survival, resulting in the lowest native species richness. The non-scalping treatments had little effect on exotic species richness in the absence of carbon or small negative effects if combined with carbon.

Comparison of different erosion control techniques in the Hyrcanian forest in northern Iran

The aim of this study was to evaluate the effects of closure best management practices (BMPs) on runoff volume and soil loss on skid trails that received two densities of soil cover mats and were located on two slope gradients in an Iranian temperate mountainous forest. The treatments included combinations of three closure BMPs (water bar only, water bar + sawdust, and water bar + hardwood slash), two amounts (densities) of mats (7.5 and 15 kg·m<sup>–2</sup>), and two levels of slope gradients (≤ 20% and > 20%). Results showed that the water bar treatment was the least effective erosion control treatment, followed by the hardwood slash and sawdust treatments. Averaged over mat densities and both slope gradients, the average runoff rates and amounts of soil loss from the skid trails with the water bar treatment were 46.7 l per plot and 6.1 g·m<sup>–2</sup>, respectively, 16.8 l per plot, 2.8 g·m<sup>–2</sup>, respectively, with the hardwood slash treatment and 11.7 l per plot, 1.9 g·m<sup>–2</sup>, respectively, with the sawdust treatment. The results indicated that surface cover is a necessary element for controlling erosion losses following a skidding disturbance, particularly on steep slopes.

Effects of conifer treatments on soil nutrient availability and plant composition in sagebrush steppe

Piñon-juniper woodlands of the western United States have expanded 2 to 10-fold since the late 1800’s. Tree control measures using chainsaws, heavy equipment and prescribed fire have been used to reduce woodlands and restore big sagebrush steppe and decrease woody fuel loading. We evaluated nutrient availability and herbaceous recovery following various cutting and prescribed fire treatments in late succession western juniper woodlands on two sites in southeast Oregon from 2007 to 2012. Sites were a cool, wet big sagebrush-Idaho fescue association (FESCUE), highly resistant to exotic annual grasses and a warm dry big sagebrush-bluebunch wheatgrass association (BLUEBUNCH), moderately resistant to annual grass invasion. Treatments were untreated controls, partial cutting followed by fall broadcast burning (SEP), cut and leave (CUT), and cut and burn in winter (JAN) and spring (APR). Soil inorganic N (NO3−, NH4+), phosphorus (H2PO4−), potassium (K+), and cover of herbaceous species were measured in three zones; interspace, litter mats around the tree canopy (canopy), and beneath felled trees (debris). Following woodland cutting, the results of the various slash treatments measured significant differences through time in the availability of inorganic N, P, and K and vegetation composition. Peak nutrient availability tended to occur within the first two years after treatment. The increases in N, P, and K were greatest in severely burned debris and canopy zones of the SEP and APR treatments. Invasive annual grass cover was positively correlated to soil inorganic N concentrations. Herbaceous composition at the FESCUE site was generally resistant to annual grasses after juniper treatments and native plants dominating post-treatment even in highly impacted debris and canopy zones of the SEP treatment. The BLUEBUNCH site was less resistance and resilient, thus, exotic annual grasses were a major component of the understory especially when tree and slash burning was of high fire severity. To lessen these impacts requires slash burning be applied from late fall to early spring, when fuel moisture and relative humidity are higher, to maintain an adequate perennial herbaceous composition for recovery.

Decomposition Patterns of Foliar Litter and Deadwood in Managed and Unmanaged Stands: A 13-Year Experiment in Boreal Mixedwoods

Litter decomposition is a major driver of carbon (C) and nitrogen (N) cycles in forest ecosystems and has major implications for C sequestration and nutrient availability. However, empirical information regarding long-term decomposition rates of foliage and wood remains rare. In this study, we assessed long-term C and N dynamics (12–13 years) during decomposition of foliage and wood for three boreal tree species, under a range of harvesting intensities and slash treatments. We used model selection based on the second-order Akaike’s Information Criterion to determine which decomposition model had the most support. The double-exponential model provided a good fit to C mass loss for foliage of trembling aspen, white spruce, and balsam fir, as well as aspen wood. These litters underwent a rapid initial phase of leaching and mineralisation, followed by a slow decomposition. In contrast, for spruce and fir wood, the single-exponential model had the most support. The long-term average decay rate of wood was faster than that of foliage for aspen, but not of conifers. However, we found no evidence that fir and spruce wood decomposed at slower rates than the recalcitrant fraction of their foliage. The critical C:N ratios, at which net N mineralisation began, were higher for wood than for foliage. Long-term decay rates following clear-cutting were either similar or faster than those observed in control stands, depending on litter material, tree species, and slash treatment. The critical C:N ratios were reached later and decreased for all conifer litters following stem-only clear-cutting, indicating increased N retention in harvested sites with high slash loads. Partial harvesting had weak effects on C and N dynamics of decaying litters. A comprehensive understanding of the long-term patterns and controls of C and N dynamics following forest disturbance would improve our ability to forecast the implications of forest harvesting for C sequestration and nutrient availability.

Rill erosion in burned and salvage logged western montane forests: Effects of logging equipment type, traffic level, and slash treatment

Following wildfires, forest managers often consider salvage logging burned trees to recover monetary value of timber, reduce fuel loads, or to meet other objectives. Relatively little is known about the cumulative hydrologic effects of wildfire and subsequent timber harvest using logging equipment. We used controlled rill experiments in logged and unlogged (control) forests burned at high severity in northern Montana, eastern Washington, and southern British Columbia to quantify rill overland flow and sediment production rates (fluxes) after ground-based salvage logging. We tested different types of logging equipment—feller-bunchers, tracked and wheeled skidders, and wheeled forwarders—as well as traffic levels and the addition of slash to skid trails as a best management practice. Rill experiments were done at each location in the first year after the fire and repeated in subsequent years. Logging was completed in the first or second post-fire year. We found that ground-based logging using heavy equipment compacted soil, reduced soil water repellency, and reduced vegetation cover. Vegetation recovery rates were slower in most logged areas than the controls. Runoff rates were higher in the skidder and forwarder plots than their respective controls in the Montana and Washington sites in the year that logging occurred, and the difference in runoff between the skidder and control plots at the British Columbia site was nearly significant (p=0.089). Most of the significant increases in runoff in the logged plots persisted for subsequent years. The type of skidder, the addition of slash, and the amount of forwarder traffic did not significantly affect the runoff rates. Across the three sites, rill sediment fluxes were 5–1900% greater in logged plots than the controls in the year of logging, and the increases were significant for all logging treatments except the low use forwarder trails. There was no difference in the first-year sediment fluxes between the feller-buncher and tracked skidder plots, but the feller-buncher fluxes were lower than the values from the wheeled skidder plots. Manually adding slash after logging did not affect sediment flux rates. There were no significant changes in the control sediment fluxes over time, and none of the logging equipment impacted plots produced greater sediment fluxes than the controls in the second or third year after logging. Our results indicate that salvage logging increases the risk of sedimentation regardless of equipment type and amount of traffic, and that specific best management practices are needed to mitigate the hydrologic impacts of post-fire salvage logging.

Effects of litter manipulation in a tropical Eucalyptus plantation on leaching of mineral nutrients, dissolved organic nitrogen and dissolved organic carbon

Although many studies have shown that soil solution chemistry can be a reliable indicator of biogeochemical cycling in forest ecosystems, the effects of litter manipulations on the fluxes of dissolved elements in gravitational soil solutions have rarely been investigated. We estimated the fluxes of NH4-N, NO3-N, K, Ca, Mg, Na, Cl, dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) over the first two years after re-planting Eucalyptus trees in the coastal area of Congo. Two treatments were replicated in two blocks after clear-cutting 7-year-old stands: in treatment R, all the litter above the mineral soil was removed before planting, and in a double slash (DS) treatment, the amount of harvest residues was doubled. The soil solutions were sampled down to a depth of 4m and the water fluxes were estimated using the Hydrus 1D model parameterized from soil moisture measurements in 4 plots. Isotopic and spectroscopic analytical techniques were used to assess the changes in dissolved organic matter (DOM) properties throughout the transfer in the soil. The first year after planting, the fluxes of NH4-N, K, Ca, Mg, Na, Cl and DOC in the topsoil of the DS treatment were 2–5 times higher than in R, which showed that litter was a major source of dissolved nutrients. Nutrient fluxes in gravitational solutions decreased sharply in the second year after planting, irrespective of the soil depth, as a result of intense nutrient uptake by Eucalyptus trees. Losses of dissolved nutrients were noticeably low in these Eucalyptus plantations despite a low cation exchange capacity, a coarse soil texture and large amounts of harvest residues left on-site at the clear cut in the DS treatment. All together, these results clarified the strong effect of litter manipulation observed on eucalypt growth in Congolese sandy soils. DOM fluxes, as well as changes in δ13C, C:N and aromaticity of DOM throughout the soil profile showed that the organic compounds produced in the litter layer were mainly consumed by microorganisms or retained in the topsoil. Below a depth of 15cm, most of the DOC and the DON originated from the first 2cm of the soil and the exchanges between soil solutions and soil organic matter were low.

Ungulate-adapted forest management: effects of slash treatment at harvest on forage availability and use

Forest management strongly influences the interactions between ungulates and their food resources. Different ungulate-adapted measures have been proposed in forestry to improve forage availability or to reduce browsing damage. However, the potential and feasibility of such measures are inadequately known. We studied the effects of harvest timing and slash treatment in final felling and commercial thinning on the availability of Scots pine Pinus sylvestris forage and its use by ungulates during winter in the Swedish boreal forests. Pellet group counts showed that moose (Alces alces) was the dominating species using the post-harvest stands. Under conventional slash treatment, final felling stands held on average 226 kg pine forage ha−1 after harvesting and commercial thinning stands 137 kg ha−1. Ungulate-adapted slash treatment increased the available forage biomass by 20 %, but had no significant effect on consumption of forage by ungulates. Time since harvest had the strongest effect on forage consumption; for example, under conventional slash treatment, there was a tenfold increase in consumption (3 vs. 33 kg ha−1) following final felling as exposure time increased from 2–3 to 4–5 months. Consumption was higher in thinned stands than in final felling stands for the first 3 months but not later. To increase ungulate use of the forage made available at harvest, pine-dominated stands should be harvested in the late autumn or early in the winter.

Vegetation Response to Western Juniper Slash Treatments

The expansion of piñon-juniper woodlands the past 100years in the western United States has resulted in large scale efforts to kill trees and recover sagebrush steppe rangelands. It is important to evaluate vegetation recovery following woodland control to develop best management practices. In this study, we compared two fuel reduction treatments and a cut-and-leave (CUT) treatment used to control western juniper (Juniperus occidentalis spp. occidentalis Hook.) of the northwestern United States. Treatments were; CUT, cut-and-broadcast burn (BURN), and cut-pile-and-burn the pile (PILE). A randomized complete block design was used with five replicates of each treatment located in a curl leaf mahogany (Cercocarpus ledifolius Nutt. ex Torr. & A. Gray)/mountain big sagebrush (Artemisia tridentata Nutt. spp. vaseyana (Rydb.) Beetle)/Idaho fescue (Festuca idahoensis Elmer) association. In 2010, 4years after tree control the cover of perennial grasses (PG) [Sandberg's bluegrass (Poa secunda J. Pres) and large bunchgrasses] were about 4 and 5% less, respectively, in the BURN (7.1±0.6%) than the PILE (11.4±2.3%) and CUT (12.4±1.7%) treatments (P<0.0015). In 2010, cover of invasive cheatgrass (Bromus tectorum L.) was greater in the BURN (6.3±1.0%) and was 50 and 100% greater than PILE and CUT treatments, respectively. However, the increase in perennial bunchgrass density and cover, despite cheatgrass in the BURN treatment, mean it unlikely that cheatgrass will persist as a major understory component. In the CUT treatment mahogany cover increased 12.5% and density increased in from 172±25 to 404±123trees/ha. Burning, killed most or all of the adult mahogany, and mahogany recovery consisted of 100 and 67% seedlings in the PILE and BURN treatments, respectively. After treatment, juniper presence from untreated small trees (<1m tall; PILE and CUT treatments) and seedling emergence (all treatments) represented 25-33% of pre-treatment tree density. To maintain recovery of herbaceous, shrub, and mahogany species additional control of reestablished juniper will be necessary.

Allometry, above-ground biomass and nutrient distribution in Ceriops decandra (Griffith) Ding Hou dominated forest types of the Sundarbans mangrove forest, Bangladesh

The Sundarbans, the world’s largest single expanse of natural mangroves located in southern Bangladesh, is the most productive mangrove ecosystem in the world. Ceriops decandra (Griff.) Ding Hou is the dominant shrub in the strong saline zone of the Sundarbans and is mainly extracted for fuel wood, charcoal and tannin. The harvest of C. decandra has decreased by about 50 % in the Sundarbans during the last 10 years creating a major concern. This study derived allometric models of above-ground biomass and estimated of above-ground standing and harvestable biomass and nutrient stock in C. decandra in dominant forest types (C. decandra and C. decandra–Excoecaria agallocha) in the Sundarbans. Allometric relationships between collar girth (CG) and biomass of plant parts (leaf, branch and stem) were tested using linear, power and logarithmic equations. The power equation was found to be most suitable. The density and the estimated total aboveground biomass of C. decandra in C. decandra and C. decandra–E. agallocha forest types were 33,237 and 965 stems/ha (density) and 33.49 and 14.36 t/ha (biomass), respectively. Also, 13.56 and 6.61 t/ha of harvestable biomass were estimated, from C. decandra and C. decandra–E. agallocha forest types, respectively. Nitrogen, potassium and phosphorus concentrations in the leaves, branches and stems showed significant (p < 0.05) variation. The findings of the present study will help to quantify the impact of present harvesting techniques and alteration of different silvicultural intervention like fixation of felling cycle, felling criterion, and regeneration and slash treatment.

Comparing Sediment Trap Data with the USLE-Forest, RUSLE2, and WEPP-Road Erosion Models for Evaluation of Bladed Skid Trail BMPs

Three erosion models, the Universal Soil Loss Equation for Forestry (USLE-Forest), the Revised Universal Soil Loss Equation Version 2 (RUSLE2), and the Water Erosion Prediction Project for Forest Roads (WEPP-Road), were compared to sediment trap data for bladed skid trail best management practices (BMPs). The bladed skid trail BMPs evaluated were: (1) water bar only (control treatment); (2) water bar + lime, fertilizer, and grass seed (seed treatment); (3) seed + straw mulch (mulch treatment); (4) control + piled hardwood slash (hardwood slash treatment); and (5) control + piled pine slash (pine slash treatment). This study used three erosion models to evaluate the BMPs while also using linear regression, model efficiency (NSE), and percent bias (PBIAS) to compare the prediction accuracy and applicability of the models to monthly erosion collected in sediment traps from six replications of the five treatments. Results showed significant treatment differences due to the BMPs, with the control treatment being the most erosive, followed generally by the seed, hardwood slash, pine slash, and mulch treatments. Model predictions indicated that all models were suitable for ranking erosion rates for the skid trail closure treatments for simple hazard or BMP ratings. However, the older and simpler USLE-Forest and RUSLE2 models had satisfactory NSE and PBIAS values, whereas WEPP-Road did not. Results indicate that WEPP-Road needs additional enhancement with regard to skid trail parameters before it can be effectively used for erosion prediction on bladed skid trails.

Evaluation of Techniques to Protect Aspen Suckers from Ungulate Browsing in the Black Hills

Abstract Excessive browsing by cattle (Bos taurus L.) and wild ungulates, particularly elk (Cervus elaphus L.), sometimes inhibits growth and maturity of quaking aspen (Populus tremuloides Michx.) suckers in Western North America. In areas where aspen stands are in poor condition or declining, protecting suckers from ungulates may be necessary. This study compared the utility of livestock fences, complete wildlife exclosures, barriers created from slash debris, and tree hinging during 2004 and 2005 in the Black Hills of South Dakota. All of the barriers significantly reduced percentage browsing of aspen suckers compared with the pretreatment average (78%) and posttreatment control (79%). Slash treatments andlivestock fences decreased ungulate browsing by 19%, hinge treatments decreased it by 39%, and wildlife fences eliminated nearly allincidences of sucker browsing. The average length removed per terminal stem for aspen suckers decreased from 20.8 to 14.4 cm across all treatments. After 1 year, the mean number of suckers above 100 cm height in both the hinge and slash treatments were significantly greater than both the fence treatments and control. Data showed that autumn and winter browsing was primarily by wild ungulates. Slash barriers can replace livestock fences where cattle affect aspen suckers. Hinge barriers are more useful than both slash barriers and livestock fences in areas where wild ungulates are the primary browsers.

Diversification of Pinus halepensis forests by sowing Quercus ilex and Quercus pubescens acorns: testing the effects of different vegetation and soil treatments

The goal of this study was to develop management strategies favouring establishment and survival of holm oak (Quercus ilex L.) and downy oak (Quercus pubescens Willd.)—two species co-occurring in Southern France—in mature Allepo pine forests (Pinus halepensis Mill subsp. halepensis). An experimental design was assessed in a partially cut mature stand of Aleppo pine in which five soil and vegetation treatments—chopping, chopping followed by scarification in one or two directions, prescribed burning, control—and two slash treatments (presence/absence) were applied. A total of 1,600 sowing points, each composed of 3 Q. ilex or Q. pubescens acorns, were installed in the different treatments in November of two consecutive years at 6 and 18 months, after the end of treatments. Survival was monitored 3 and 2 years after sowing, soil surface at the sowing points was characterized at different dates, and predawn leaf water potentials were measured during the dry season. High mortality occurred after the first summer, but survival after 1 year was 2.3–5.2 higher in Q. ilex than in Q. pubescens, confirming that Q. ilex was better adapted to the drier parts of the Mediterranean area. Survival was significantly influenced by the treatments, but there was a variable response between the two sowing years under most of the treatments. Only intense fire proved the most beneficial treatment for seedling survival in both years. The micro-local soil cover conditions induced by the treatments played a major role in explaining oak survival. In particular, grass cover (mainly Brachypodium retusum) proved to be largely unfavourable to seedling survival and growth, and this detrimental effect was also confirmed by lower predawn leaf water potential values with increasing grass cover. Acorn introduction designed to diversify mature Aleppo pine forest after soil and vegetation treatments therefore has to be considered for treatments that most efficiently impair the pre-existing competing grass cover such as prescribed high-intensity fire treatment.

Response of maritime pine (Pinus pinaster Ait.) recruitment to fire severity and post-fire management in a coastal burned area in Galicia (NW Spain)

The short-term effects of fire severity and post-fire management on maritime pine recruitment were evaluated in a mature serotinous pine stand in a coastal area of Galicia (NW Spain) burned by a wildfire occurred in the summer of 2001. Two levels of fire severity estimated by the levels of tree crown damage—scorched and unaffected crown—were compared. Seed dispersal and first cohort pine (November 2001) seedling density, before salvage logging, were significantly and positively affected by fire severity. Between November and January, a fungal attack caused a noticeable decrease in seedling density in both levels of fire severity. The first cohort survival was significantly reduced by harvesting and slash treatments carried out in February 2002. However, slash chopping favoured a new pine cohort, particularly in the unaffected crown plots, in which seedling density was significantly higher than in the scorched crown plots between July 2002 and February 2003. First cohort seedling survival and height were positively related. Fire severity levels, combined with post fire management, did not appear to determine final pine seedling density and height. Finally, reduction in seedling density caused by post-fire management did not threaten pine establishment and may reduce the need for subsequent thinning operations.

Regeneration of Pinus halepensis stands after partial cutting in southern France: Impacts of different ground vegetation, soil and logging slash treatments

This study investigated the effects of different soil, ground vegetation and logging slash treatments on Aleppo pine recruitment in a mature stand after partial cut in southern France. An experimental design was assessed using five treatments: (1) chopping of the ground vegetation, (2) chopping followed by soil scarification in one or (3) in two directions, (4) controlled fire, (5) control—and two logging slash treatments: (1) presence or (2) absence of slash cover before the soil and ground vegetation treatments. Pine seedling emergence and survival were recorded on 580 one-square-meter plots at the end of spring and autumn from autumn 2005 to autumn 2007. Description of the soil surface conditions in cover classes was also established in each plot at the end of the year. Seedling emergence took place predominantly in autumn except for the last year of the experiment due to a severe drought period. Soil scarification treatments and controlled fire with slash present (i.e. intense fire) showed the highest seedling densities and bare soil cover was also the highest in these treatments. By contrast, a lower seedling density was recorded in the controlled fire without slash (i.e. moderate fire) where grass cover largely developed. Chopping also proved to be unfavorable to seedling emergence and survival. Seedling emergence was enhanced by the presence of logging slash in the moderate soil scarification treatment probably due to the additional seed source provided by the breakdown of the cones in the slash. The study showed the importance of mechanical treatments – in particular scarification – to favor pine recruitment. However a longer period of data recording is requested to analyze the response of pine seedlings to developing ground vegetation development in the coming years.

Effects of Slash on Herbaceous Communities in Pinyon–Juniper Woodlands of Northern Arizona

Scattering slash (downed woody materials) after tree removal is increasingly prescribed by land managers as a treatment to promote the establishment and growth of understory vegetation in pinyon–juniper woodlands. However, the effects of scattering slash on soil resources and plant communities are poorly understood and often confounded with the release from tree competition. In order to examine how slash affects plant establishment, soil stability, soil nutrients, and soil microbiota, we initiated a 2 × 2 full factorial experiment with two levels of seeding and two levels of slash additions within 30 intercanopy spaces, repeated at two intact pinyon–juniper woodland sites with different soil characteristics in northwestern Arizona. Pretreatment data were collected in 2003 and posttreatment responses were measured in 2004 and 2005. Total plant cover increased within all treatments; however, grasses increased significantly only in the seed-and-slash treatment at both sites. In addition, a greater proportion of seed-and-slash plots contained more reproductively active grasses compared to seed-only plots. Slash treatments also resulted in significantly less sediment movement compared to nonslash treatments. Changes in soil nutrients were not observed, except available NO3-N decreased significantly in slash treatments. Arbuscular mycorrhizal potential and microbial biomass carbon increased as a result of the slash treatment. Addition of woody materials appeared to have general effectiveness at improving the ecological function of soils and promoting understory establishment and thus may be considered a desirable treatment for improving degraded conditions. La dispersión de la tala (materiales leñosos derribados) después de la remoción del árbol es prescrita cada vez más por los administradores de tierras como un tratamiento para promover el crecimiento y el establecimiento de la vegetación del sotobosque en los bosques de pino piñonero y enebro. Sin embargo, los efectos de la dispersión de la tala en las comunidades de plantas y en los recursos del suelo son pobremente comprendidos y a menudo confundidos con la liberación de la competencia arbustiva. En orden para examinar como la tala afecta el establecimiento de la planta, la estabilidad del suelo, los nutrientes del suelo y la micro biota del suelo, nosotros iniciamos un experimento factorial completo 2 × 2 con dos niveles de siembra y dos niveles de adicción de tala en 30 espacios dentro del dosel, repitiéndolo en dos sitios intactos de bosque de pino piñonero y enebro de diferentes características de suelo en el noroeste de Arizona. Los datos previos al tratamiento fueron colectados en el 2003 y las respuestas posteriores al tratamiento fueron medidas en el 2004 y 2005. La cobertura vegetal total aumentó en todos los tratamientos, sin embargo las hierbas aumentaron significativamente sólo en el tratamiento de semilla y tala en ambos sitios. Además, una mayor porción de parcelas semillas y tala contuvieron más hierbas reproductivamente activas comparadas a las parcelas de solo semilla. Los tratamientos de tala también resultaron significativamente en menos movimiento de sedimento comparado a los tratamientos de no tala. No se observaron cambios en los nutrientes del suelo, excepto el N03-N disponible que disminuyó significativamente en los tratamientos de tala. El potencial micorrízico arbuscular y el carbono en la biomasa microbiana se incrementaron como resultado al tratamiento de tala. La adicción de los materiales leñosos parece tener una efectividad general en mejorar la función ecológica de los suelos y en promover el establecimiento del sotobosque, y de este modo se podría considerar como un tratamiento conveniente para mejorar las condiciones degradadas.

Effects of wildfire, salvage logging and slash manipulation on Pinus pinaster Ait. recruitment in Orense (NW Spain)

Abstract The effect of wildfire and the subsequent harvesting on P. pinaster recruitment was evaluated in a burned stand of this species in Orense (Galicia, NW Spain). Most of the seedling emergence (88%) that occurred during the first year after wildfire, took place between the end of the winter and the beginning of the spring, although meteorological conditions during the first autumn after fire were not adverse. The mild environmental conditions during the first summer after wildfire resulted in very low seedling mortality. The degree of crown damage caused by wildfire significantly and negatively affected pine seedling stocking, which was, as average, 3.5 seedlings m −2 at the end of the first year after wildfire. Salvage logging was carried out 13 months after the fire. Three post-fire alternatives were compared: no harvesting (standing burned trees), harvesting + windrowing slash and harvesting + slash chopping. Slash chopping favoured a new seedling cohort. Harvesting and slash windrowing caused an immediate seedling mortality of 22%. Harvesting and slash chopping operations caused a mean mortality of 18 and 31%, respectively. Averaged over both slash treatments, 27% of the seedlings were damaged, which increased deferred mortality during the subsequent months. Pine seedling survival was significantly related to seedling height, especially in harvested plots and was significantly reduced by harvesting and logging slash operations, with this reduction significantly higher in the harvest + slash chopping treatment. Harvesting and slash manipulation significantly reduced seedling height and growth, especially after slash chopping. The percentage of bare soil resulting from clearcutting was significantly and negatively related to P. pinaster density, survival and height. Because of the contribution of the new cohort, at the end of the study there were no differences in seedling density related to treatment; the densities ranged from 3.4 seedlings m −2 in the non-harvested treatment to 2.5 seedlings m −2 in harvest + slash windrowing treatment, whereas in the harvest + slash chopping treatment these were 3.2 seedlings m −2 . The delay in harvesting may have lessened the impact of these forestry operations on P. pinaster recruitment. Reduction in seedling density caused by harvest and slash manipulation operations might reduce the need for subsequent thinning operations.