Partial Cuts Research Articles

Influence of tendon tears on ultrasound echo intensity in response to loading

Acoustoelastic (AE) ultrasound image analysis is a promising non-invasive approach that uses load-dependent echo intensity changes to characterize stiffness of tendinous tissue. The purpose of this study was to investigate whether AE can detect localized changes in tendon stiffness due to partial and full-thickness tendon tears. Ovine infraspinatus tendons with different levels of damage (Intact, 33%, 66% and full thickness cuts initiated on the articular and bursal sides) were cyclically loaded in a mechanical testing system while cine ultrasound images were recorded. The load-induced changes in echo intensity on the bursal and articular side of the tendon were determined. Consistent with AE theory, the undamaged tendons exhibited an increase in echo intensity with tendon loading, reflecting the strain-stiffening behavior of the tissue. In the intact condition, the articular region demonstrated a significantly greater increase in echo intensity during loading than the bursal region. Cuts initiated on the bursal side resulted in a progressive decrease in echo intensity of the adjacent tissue, likely reflecting the reduced load transmission through that region. However, image intensity information was less sensitive for identifying load transmission changes that result from partial thickness cuts initiated on the articular side. We conclude that AE approaches may be useful to quantitatively assess load-dependent changes in tendon stiffness, and that disruption of AE behavior may be indicative of substantial tendon damage.

A framework to optimize the restoration and retention of large mature forest tracts in managed boreal landscapes.

The decreasing abundance of mature forests and their fragmentation have been identified as major threats for the preservation of biodiversity in managed landscapes. In this study, we developed a multi-level framework to coordinate forest harvestings so as to optimize the retention or restoration of large mature forest tracts in managed forests. We used mixed-integer programming for this optimization, and integrated realistic management assumptions regarding stand yield and operational harvest constraints. The model was parameterized for eastern Canadian boreal forests, where clear-cutting is the main silvicultural system, and is used to examine two hypotheses. First, we tested if mature forest tract targets had more negative impacts on wood supplies when implemented in landscapes that are very different from targeted conditions. Second, we tested the hypothesis that using more partial cuts can be useful to attenuate the negative impacts of mature forest targets on wood supplies. The results indicate that without the integration of an explicit mature forest tract target, the optimization leads to relatively high fragmentation levels. Forcing the retention or restoration of large mature forest tracts on 40% of the landscapes had negative impacts on wood supplies in all types of landscapes, but these impacts were less important in landscapes that were initially fragmented. This counter-intuitive result is explained by the presence in the models of an operational constraint that forbids diffuse patterns of harvestings, which are more costly. Once this constraint is applied, the residual impact of the mature forest tract target is low. The results also indicate that partial cuts are of very limited use to attenuate the impacts of mature forest tract targets on wood supplies in highly fragmented landscapes. Partial cuts are somewhat more useful in landscapes that are less fragmented, but they have to be well coordinated with clearcut schedules in order to contribute efficiently to conservation objectives. This modeling framework could easily be adapted and parameterized to test hypotheses or to optimize restoration schedules in landscapes where issues such as forest fragmentation and the abundance of mature or old-growth forests are a concern.

Sapling recruitment and mortality dynamics following partial harvesting in aspen-dominated mixedwoods in eastern Canada

Boreal mixedwood management has shifted from a relatively narrow focus on commercial wood supply to greater consideration of the natural dynamics and multiple ecological services. This recognition has generated interest in ecosystem management approaches that include diversifying and adapting silvicultural practices, including partial harvesting. The effects of partial harvesting on stand dynamics was assessed over a 12-year period in trembling aspen (Populus tremuloides Michx.) dominated stands in northwestern Quebec, Canada. Four treatments were tested: clearcuts (100% basal area (BA) removal); 1/3 partial cut (1/3 PC, 33% BA removal using low thin); 2/3 partial cut (2/3 PC, 61% BA removal using high thin) and controls (0% removal). Aspen sapling recruitment was directly affected by harvesting intensity with 1/3 and 2/3 partial cuts generating 5% and 56%, respectively, of aspen sapling densities in clearcuts. Aspen sapling recruitment increased continuously following clearcut and partial cut treatments with no significant mortality in the sapling layer over the 12-year period. Recruitment of conifer saplings also increased with time and was significantly higher in the two partial cuts than in the clearcut treatment. Twelve years after treatments, mortality of residual aspen stems (⩾10cm DBH) reached 250stemsha−1 12yr−1 in controls, compared to 106, and 170stemsha−1 12yr−1 in 1/3 PC, and 2/3 PC stands, respectively. Initially (1–3years after treatments), higher overstory aspen mortality was associated with the 2/3 PC treatment. Aspen mortality was strongly associated with small-sized merchantable stems (10–19.9cm DBH) regardless of treatment. Both partial harvesting treatments had the effect of maintaining mountain maple (Acer spicatum Lamb.), a shade-tolerant, high woody shrub, at densities similar to those in control stands whereas recruitment of mountain maple saplings was negligible in clearcuts due to high aspen recruitment. Our results indicate that (i) heavy-high partial harvesting promotes sapling recruitment of both aspen and conifers when advance regeneration of the latter is present, (ii) because aspen sucker response can be controlled by varying harvesting intensities and stem selection, it is possible to create a range of mixedwood conditions, depending on whether mixed, structurally complex or more regular aspen-dominated stands are desired, and (iii) on rich mixedwood sites, tall woody shrubs could hinder desirable partial harvesting outcomes.

Integrating standing value estimations into tree marking guidelines to meet wood supply objectives

The identification of low-vigor trees with potential for sawlog production is a key objective of tree marking guidelines used for partial cuts in northern hardwoods. The aim of this study was to measure the impact of various vigor-related defects on the monetary value of hardwoods. To achieve this, we sampled 64 sugar maple (Acer saccharum Marshall) and 32 yellow birch (Betula alleghaniensis Britton) trees from two locations in southern Quebec, Canada. We identified over 420 defects, which were grouped into 8 categories. The trees were then harvested and processed into lumber, and the value per unit volume of each stem was calculated from the value of the product assortment (lumber, chips, and sawdust). We found that visible evidence of fungal infections (sporocarps and (or) stroma) and cracks had the largest negative influence on value in both species. A model that included these defects was almost as good at predicting value as one that included a specifically designed quality classification. A more accurate assessment of value could be achieved using wood decay assessment tools and (or) by considering site-specific variables. Results from this study showed that visual identification of fungal infections and cracks could be used to enhance tree marking guidelines for hardwoods. This would meet both the silvicultural objective of selection cuts, by removing low-vigor trees, and the wood supply objective, by improving stem quality assessment prior to harvest.

Trembling aspen (Populus tremuloides Michx.) volume growth in the boreal mixedwood: Effect of partial harvesting, tree social status, and neighborhood competition

Variable retention harvesting, with a focus on maintaining biological legacies on managed landscapes, has been practised in the trembling aspen (Populus tremuloides Michx.) dominated boreal mixedwood forests for about two decades. However, little attention has actually been given to the growth response of aspen to partial harvesting. This is the first study to report on tree-level volume growth response of aspen after partial or variable retention harvesting in the Canadian boreal forest. During the winter of 1998–1999, an uncut control, clearcut and two partial harvesting treatments – 1/3 partial cut (1/3PC, 33% BA removal using low thin); 2/3 partial cut (2/3PC, 61% BA removal using high thin) – were applied in 75year old aspen-dominated mixedwood stands in a complete randomized block design. Twelve years after treatment application, 27 dominant and 27 co-dominant trees were collected from unharvested controls and the two partial cut treatments for stem analysis. Annual volume increment (AVI) of individual stems was analyzed as a function of treatment, tree social status, pre-treatment growth, time since treatment application (1–12years) and neighborhood competition. The latter was estimated using a variety of neighborhood competition indices (NCI). There was no evidence of initial growth stagnation after partial harvesting applications. Only the most severe treatment of partial harvesting (2/3 PC) resulted in an increase in volume increment relative to trees in control stands. Annual increase in volume in the 2/3 partial cut was 25.6% higher than controls over 12years. AVI of dominant trees was higher by 16.2dm3yr−1 than that of co-dominants and was proportional to pre-treatment volume growth. No interaction between treatment and social status or pre-treatment growth was observed. The overall results indicate that competition for resources in these stands is essentially size symmetrical. These results should contribute to the development of silviculture prescriptions that aim to maintain both stand productivity and biological legacies.

Growth Response of Northern White-Cedar (Thuja occidentalis) to Natural Disturbances and Partial Cuts in Mixedwood Stands of Quebec, Canada

Northern white-cedar (Thuja occidentalis) is a species of high commercial and ecological value, the abundance of which has been declining since the middle of the 19th century. Very little information regarding its silviculture in mixedwood stands is currently available, even though a significant portion of wood resources comes from these stands. The present study is a retrospective analysis of white-cedar growth in partially harvested mixedwood stands of western Quebec, Canada. Eight stands distributed across two regions were analyzed. Dendrochronological approaches examined long-term diameter growth for sample white-cedar trees and stems of associated species. These approaches were used to reconstruct stand characteristics at the time of harvesting, together with local harvesting intensity. The study demonstrated white-cedar’s capacity to maintain good growth for long periods of time and at large tree sizes. Accession to the upper canopy positions occurs through repeated episodes of suppression/release, most of which seem to be associated with spruce budworm (Choristoneura fumiferana) outbreaks. White-cedar response to partial harvesting varies with tree size, residual basal area and species composition. Growth response was generally stronger for small trees, even though large trees still maintained the best diameter growth. Growth of white-cedar was negatively affected by an increase in softwood proportion in basal area. Growth responses to harvesting could be sustained for a period of 20 years.

Regeneración post-incendio de la encina en pinares de repoblación mediterráneos

Leverkus, A.B., Castro, J., Rey Benayas, J.M. 2014. Post-fire regeneration of the Holm oak in Mediterranean pine reforestations. Ecosistemas 23(2): 48-54 . Doi.: 10.7818/ECOS.2014.23-2.07 The extraction of the burnt wood is a common practice after wildfire, yet its effects on the recolonisation by Quercus species are poorly known. We established an 18-ha plot in a burnt pine reforestation in Sierra Nevada (S Spain), with three experimental wood-management treatments: Salvage Logging (felling the trees, chopping off the main branches, piling the logs, and masticating the remaining branches), Partial Cut (felling 90 % of the trees without further actions), and Control (no actions taken). Some clusters of pines survived within the limits of the plot and were left standing (totalling 1.5 ha), and adjacent to the plot were some unburnt, acorn-producing Holm oaks ( Quercus ilex subsp. ballota) from which biotic dispersal occurred. We monitored emergence, survival, and size of oak seedlings in the plot for seven years. We found 801 oaks the first year, corresponding either to post-fire resprouts or to acorns dispersed right after the fire and before treatment implementation. After post-fire treatment implementation, 447 seedlings emerged throughout the plot, likely due to dispersal by European jays ( Garrulus glandarius ): 62.9 % under live pines and 37.1 % in the rest of the plot. Emergence was greatest in Control during the first years. The treatment factor lost importance in later years, as acorn dispersal became more directed towards the live pines. Seedlings under pines had greater survival but lower growth, likely due to competition for nutrients, light, and water. We conclude that small patches of pines that survive a fire, as well as dead standing trees during the first years, can attract acorn dispersers and that, in case of the surviving pines, a second disturbance will be needed to free the recruited oaks from competition. Management practices that favour these structures can aid the natural recovery of the ecosystem.

Shelterwood cutting to release coniferous advance growth and limit aspen sucker development in a boreal mixedwood stand

Stratified mixtures of pioneer hardwoods sheltering shade-tolerant conifers are commonly encountered in the southern boreal forest. We used two-step shelterwood cutting to release conifer advance growth and limit trembling aspen (Populus tremuloides Michx.) development in a stratified mixed aspen–conifer stand in Quebec, Canada. This paper presents 10-year regeneration dynamics after the establishment cut applied with different cutting intensities (0%, 35%, 50%, 65%, and 100% basal area removal). Aspen suckering was proportional to cutting intensity (p<0.001) and its survival was limited under all four densities of residual cover. After 10years, aspen density was ⩽600 stems/ha in the 0%, 35%, and 50% cuts, 1600stems/ha in the 65% cut and 4700stems/ha in the clearcut. Adequate protection of balsam fir (Abies balsamea (L.) Mill.) and spruce (Picea glauca (Moench) Voss and Picea mariana (Mill.) BSP) advance regeneration strongly contributed to limiting aspen development. The release treatment affected conifer sapling height growth, stem diameter, crown length growth and live crown ratio. Generally, the growth reaction to canopy removal was better in the clearcut than in partial cuts. Balsam fir response was good in the two initial height classes studied (130–300 and 301–500cm), but a significant spruce response occurred only in the smallest class. The final cut will be necessary to assess the overall effect of two-step shelterwood cutting on species composition and growth of the new cohort.

Femtosecond laser-assisted keratoplasty: full and partial-thickness cut wound strength and endothelial cell loss across a variety of wound patterns

PurposeTo evaluate wound strength for patient safety during transport and endothelial viability when partial and complete femtosecond laser-assisted keratoplasty (FLAK) incisions are made in cadaveric corneas.Methods19 human corneoscleral rims were...

Sediment dynamics following active management of a stream buffer zone: A case study

In this case study, change in sediment yield over a one year period was examined on paired watersheds (treated vs. reference) located in east Alabama. The effect of a partial cutting within a stream buffer zone (SBZ) on sediment yield was explored as well as the relative effects of pastoral, forested, and clearcut areas. During the no-harvest (calibration) period, upstream pastoral area generated much more sediment load per unit area than downstream forested sections during rainfall events. A partial cut within an SBZ changed the sediment pattern of downstream sections of the treatment watershed. On the treated sections, the observed sediment yield was higher than expected while there was no significant change in sediment yield from the pastoral area. Some of this increase was attributed to seasonal effects due to reduction in evapotranspiration. There was no change in the sediment yield pattern of the control watershed. The partial cut within the SBZ played a much more critical role than the stream road crossing as the sediment source. This study further shows that a holistic approach is needed to control sediment yield in mixed land use watersheds.

Post-fire salvage logging alters species composition and reduces cover, richness, and diversity in Mediterranean plant communities

An intense debate exists on the effects of post-fire salvage logging on plant community regeneration, but scant data are available derived from experimental studies. We analyzed the effects of salvage logging on plant community regeneration in terms of species richness, diversity, cover, and composition by experimentally managing a burnt forest on a Mediterranean mountain (Sierra Nevada, S Spain). In each of three plots located at different elevations, three replicates of three treatments were implemented seven months after the fire, differing in the degree of intervention: “Non-Intervention” (all trees left standing), “Partial Cut plus Lopping” (felling 90% of the trees, cutting the main branches, and leaving all the biomass in situ), and “Salvage Logging” (felling and piling the logs, and masticating the woody debris). Plant composition in each treatment was monitored two years after the fire in linear point transects. Post-fire salvage logging was associated with reduced species richness, Shannon diversity, and total plant cover. Moreover, salvaged sites hosted different species assemblages and 25% lower cover of seeder species (but equal cover of resprouters) compared to the other treatments. Cover of trees and shrubs was also lowest in Salvage Logging, which could suggest a potential slow-down of forest regeneration. Most of these results were consistent among the three plots despite plots hosting different plant communities. Concluding, our study suggests that salvage logging may reduce species richness and diversity, as well as the recruitment of woody species, which could delay the natural regeneration of the ecosystem.

Persistent radiographic cone cuts: a simple test to avoid the frustrating problem.

In routine dental radiography, one may encounter numerous radiographic errors, one of which may be partial images or cone cuts. These cones cut errors although may appear as simple problems, but often persistent cone cuts may be frustrating to the dental practitioner. In this study, our main aim was to find and solve the origin of the problem. This study was conducted with two different intraoral X-ray machines with 12 inch length position indicating devices (PIDs) with four No. 2 intraoral films. If the problem is originated in the X-ray machine, it can be solved by either tapping the collimator or by repositioning the PID.

Rescue of Primary Incomplete Microkeratome Flap with Secondary Femtosecond Laser Flap in LASIK

For laser-assisted in situ keratomileusis (LASIK) retreatments with a previous unsuccessful mechanical microkeratome-assisted surgery, some surgical protocols have been described as feasible, such as relifting of the flap or the creation of a new flap and even the change to a surface ablation procedure (photorefractive keratectomy (PRK)). This case shows the use of femtosecond technology for the creation of a secondary flap to perform LASIK in a cornea with a primary incomplete flap obtained with a mechanical microkeratome. As we were unable to characterize the interface of the first partial lamellar cut, a thick flap was planned and created using a femtosecond laser platform. As the primary cut was very thick in the nasal quadrant, a piece of loose corneal tissue appeared during flap lifting which was fitted in its position and not removed. Despite this condition and considering the regularity of the new femtosecond laser cut, the treatment was uneventful. This case report shows the relevance of a detailed corneal analysis with an advanced imaging technique before performing a secondary flap in a cornea with a primary incomplete flap. The femtosecond laser technology seems to be an excellent tool to manage such cases successfully.

Once again about determination of saving of energy for traction due to partial cut–off of traction engines of electric rolling stock

Purpose. In general the well known methods for determination of energy saving due to the partial traction engines cut-off based on their comparison to efficiency coefficient or to the power of energy losses do not allow objective estimation of efficiency of these measures and in a number of cases result in erroneous results and errors. The search for new more advanced methods for determination of energy saving at the partial cut-off of the traction engines is needed. Methodology. The method of calculation determination of energy saving when partial cutting-off of the traction engines is offered. It is based on the use of rationality coefficient as the loading mode of the electric power consumption for the measuring instrument of transportation activity. Findings. Using the given mathematical expressions it is possible to determine the energy saving in both the relative and absolute values and set the terms (motion speed and route gradient), under which the energy saving will take place. Originality. The method of the task solving, which is based on the evaluation of energy consumption differences for the compared variants (not on the comparison of efficiency coefficient or differences of power of energy losses) is offered. Practical value. The given methodology allows obtaining more exact conclusions in relation to the electric power consumption, as the comparison of energy losses power or the efficiency coefficient does not determine precisely the electric power consumption for traction. Therefore the conclusions based on the comparison of power of energy losses or efficiency coefficient can appear inexact.

Post-fire wood management alters water stress, growth, and performance of pine regeneration in a Mediterranean ecosystem

Extensive research has focused on comparing the impacts of post-fire salvage logging versus those of less aggressive management practices on forest regeneration. However, few studies have addressed the effects of different burnt-wood management options on seedling/sapling performance, or the ecophysiological mechanisms underlying differences among treatments. In this study, we experimentally assess the effects of post-fire management of the burnt wood on the growth and performance of naturally regenerating pine seedlings (Pinus pinaster). Three post-fire management treatments varying in degree of intervention were implemented seven months after a high-severity wildfire burned Mediterranean pine forests in the Sierra Nevada, southeast Spain: (a) “No Intervention” (NI, all burnt trees left standing); (b) “Partial Cut plus Lopping” (PCL, felling most of the burnt trees, cutting off branches, and leaving all the biomass on site without mastication); and (c) “Salvage Logging” (SL, felling the burnt trees, piling up the logs and masticating the fine woody debris). Three years after the fire, the growth, foliar nutrient concentrations, and leaf carbon, nitrogen and oxygen isotopic composition (δ13C, δ18O and δ15N) of naturally regenerating seedlings were measured in all the treatments. Pine seedlings showed greatest vigor and size in the PCL treatment, whereas growth was poorest in SL. The nutrient concentrations were similar among treatments, although greater growth in the two treatments with residual wood present indicated higher plant uptake. Seedlings in the SL treatment showed high leaf δ13C and δ18O values indicating severe water stress, in contrast to significantly alleviated water stress indications in the PCL treatment. Seedling growth and physiological performance in NI was intermediate between that of PCL and SL. After six growing seasons, P. pinaster saplings in PCL showed greater growth and cone production than SL saplings. In summary, salvage logging has a detrimental effect on the ecophysiological performance and growth of naturally regenerating pine seedlings, compared to alternative post-fire management practices in which burnt logs and branches are left in situ. Improved seedling growth and performance is associated with the amelioration of microsite/microclimate conditions by the presence of residual burnt wood, which alleviates seedling drought stress and improves nutrient availability through the decomposition of woody debris.

Study on Structural Design and Driving Process of a Subway Station with Large Transection by Tunneling Method

Structural design and construction process for a subway station consists of two tunnels with large transection are discussed according to its function and geological conditions of rock mass in this paper. A composite lining is designed to support surrounding rock, and partial bench cut method, side drift method are utilized to build the special subway transfer station in rock mass. The practice of the designed scenario proves to be a great success and attains the safe construction of the station by tunneling method.

Shelterwood and multicohort management have similar initial effects on ground beetle assemblages in boreal forests

Partial cutting has been proposed as a means to better conserve biodiversity in managed forest landscapes. However, partial cutting encompasses many forms of silviculture; some with implicit goals of maintaining biodiversity such as multicohort harvesting or others which may specifically focus on regeneration of stands but may still provide some additional benefits for biodiversity such as shelterwood harvesting. Here we compared ground beetle assemblages of clear cuts, shelterwoods, multicohort harvested stands and uncut stands collected using pitfall traps both 2 and 3-years post-harvest. We hypothesized that partial cutting treatments would maintain assemblages that were more similar to uncut stands than to clear cuts. We further hypothesized that among partial cuts the multicohort harvested stands, with relatively high levels of retention (66%), would maintain beetle assemblages that were more similar to uncut stands than would shelterwoods, which had lower levels of retention (50%). We collected 6692 individuals, representing 42 species. Catch rates of beetles were similar among all harvested treatments (shelterwood, multicohort and clear cuts) and lower than uncut stands. Species richness and composition was similar between shelterwood and multicohort stands. Both partial cut treatments fell between clear cuts and uncut stands in terms of species richness and compositional similarity. Compositional differences between uncut stands and partial cut stands were defined primarily by reduced abundances of forest associated species such as Agonum retractum (LeConte), Synuchus impunctatus (Say) and four Pterostichus species within partial cuts. Within partial cuts, beetle assemblages differed between machine corridors with 0% retention and adjacent partial cut strips (50% retention) and uncut vegetation corridors (100%). We conclude that both shelterwoods and multicohort harvesting stands provide at least initially similar benefits for biodiversity compared to clear cutting although neither maintains assemblages consistent with those found in uncut stands. We expect that these similarities will end once trees are removed from shelterwoods. The reductions in abundances within partial cuts may extend the time necessary for individual populations to increase to pre-harvest levels in partial cuts. For land-managers, similar initial responses of beetle assemblages in multicohort and shelterwood harvests may permit some flexibility for conservation planning whereby final removal of seed trees within shelterwoods could be delayed depending on the status of recovering beetle populations.

Performance of planted spruce and natural regeneration after pre- and post-harvest spraying with glyphosate and partial cutting on an Ontario (Canada) boreal mixedwood site

In the boreal mixedwood region of Canada, management for conifer regeneration after clearcutting generally involves mechanical site preparation, planting and aerial spraying with glyphosate to minimize post-planting competition from natural broadleaf regeneration. However, the resulting conifer plantations have economic and ecological disadvantages compared with mixedwood stands with healthy and productive broadleaf components. This study examined 10-year growth of planted spruce and natural regeneration after pre- and post-harvest spraying and partial cutting treatments on a boreal mixedwood site in northeastern Ontario, Canada. The treatments were as follows: (1) pre-harvest broadcast spraying with glyphosate to suppress trembling aspen (Populus tremuloides Michx.) regeneration, (2) clearcut (unsprayed) for broadleaf regeneration, (3) partial cut to suppress shade-intolerant vegetation, and (4) post-harvest broadcast spraying to promote conventional conifer plantations. Planted spruce trees were tallest in the pre-harvest spray treatment but had the largest basal diameter in the post-harvest spray treatment; neither of the differences was significant at 0.05. Total broadleaf regeneration density in the pre-harvest spray treatment was similar to that in the partial cut, but higher than that in the post-harvest spray treatment. Additional shade from greater amounts of shrubs and residual overstory trees in the partial cut treatment resulted in higher quality spruce trees than in the spray treatments; based on branch size, branch-free stem length and stem taper, wood quality was generally lowest in the post-harvest spray treatment. Pre-harvest spraying provided a better balance between growth and quality of planted spruce than either post-harvest spraying or partial cutting.

Canopy openings created by partial cutting increase growth rates and maintain the cover of three Cladonia species in the Canadian boreal forest

In boreal forests partial cutting is often proposed as an alternative to the widespread use of clearcutting to better conciliate forest management with species conservation. A partial cutting experiment was implemented in black spruce boreal forests of western Québec, and the responses of three terricolous lichen species (Cladonia stellaris, C. mitis, and C. rangiferina) to three different treatments of different removal intensities (old unharvested forest stands and old forests treated by partial cutting and clearcutting) were studied. We used transplants of lichens to record growth rate over a period of 15months, and we also recorded microclimatic variables (thallus temperature, thallus humidity, and photosynthetically active radiation [PAR]) directly at the sampling sites. We observed reduced growth rates in C. stellaris and C. rangiferina transplants located in untreated control plots compared with transplants located either in stands treated with partial cutting and or stands treated by clearcutting. We also found that lichen growth differed significantly across season, with a higher growth rate during the first summer compared to the other seasons. Lichen cover and frequency (presence or absence) of the three Cladonia species did not differ significantly between partial cut plots and control plots. PAR and thallus temperature were significantly lower in control plots, while thallus humidity was significantly higher in control plots. Thallus humidity recorded in the morning (between 6 am and 9 am) showed a reversed pattern, with lower values in control plots compared with partial cutting and clearcutting plots. Our results show that canopy openings in the partial cuttings had a positive influence on the growth of Cladonia species, probably through an increase in the quantity of light and humidity reaching the thalli early in the morning. Furthermore, canopy openings resulting from partial cuttings can maintain pre-established lichen cover at levels comparable to what is observed in our unharvested control stands.

Do partial cuts create forest complexity? A new approach to measuring the complexity of forest patterns using photographs and the mean information gain

Forest management generally simplifies forest structure and composition with some negative impacts in terms of biodiversity and resilience. Thus, maintaining structural complexity is increasingly cited as an objective of sustainable forest management. Different initiatives have been proposed to use partial cuts to increase the complexity of forests. Using “the length of description” of forest patterns as a novel measure of complexity in forests, the effects of two intensities of partial cuts were compared to those found in 34-year-old secondary forests and 86-year-old primary (post-fire) forests. Our results show that partial cuts increase the complexity of forest patterns as compared to mature and secondary forests.