Diameter distributions in Pinus sylvestris L.stands:evaluating modelling approaches including a machine learning technique

The diameter distribution of trees in a stand provides the basis for determining the stand’s ecological and economic value,its structure and stability and appropriate management practices.Scots pine(Pinus sylvestris L.)is one of the most common and important conifers in Turkey,so a well-planned management schedule is critical.Diameter distribution models to accurately describe the stand structure help improve management strategies,but developing reliable models requires a deep understanding of the growth,output and constraints of the forests.The most important information derived by diameter distribution models is primary data on horizontal stand structure for each diameter class of trees:basal area and volume per unit area.These predictions are required to estimate the range of products and predicted volume and yield from a forest stand.Here,to construct an accurate,reliable diameter distribution model for natural Scots pine stands in the Türkmen Mountain region,we used Johnson’s SBdistribution to represent the empirical diameter distributions of the stands using ground-based measurements from 55 sample plots that included1219 trees in natural distribution zones of the forests.As an alternative,nonparametric approach,which does not require any predefined function,an artificial intelligence model was constructed based on support vector machine methodology.An error index was calculated to evaluate the results.Overall,both Johnson’s SB probability density function with a three-parameter recovery approach and the support vector regression methodology provided reliable estimates of the diameter distribution of these stands.

Physical,Anatomical,and Photochemical Analyses of Some ExoticWood Species Submitted to Heat Treatment

The objective of this study was to evaluate the effect of heat treatment on decorative properties including glossiness,color coordinates including lightness(L),blue-yellow(b^(*))and red-green(a^(*)),hardness(shore-D)morphological characterization and thermal properties of some exotic wood species.Heat treatment of anigre(Aningeria altissima),cedrorana(Cedrelinga catenaeformis),cemara(Casuarina sumatrana)and coronilla(Scutia buxifolia)wood materials were performed in an oven with a programmable controller at 210°C for 3 h.The obtained samples were conditioned in a climate cabin and the decorative properties,morphological characterization with scanning electron microscopy(SEM)and thermal properties with thermogravimetric analyzer(TGA)of the obtained samples were determined.The test results showed that color got darker with heat treatment,specifically L and b^(*)decreased,and a^(*)increased for anigre and cedrorana but a^(*)decreased for cemara and coronilla.The glossiness for all samples generally increased from 20°to 85°but heat treatment decreased the glossiness.The density generally decreased with heat treatment and decrease ratio in the density was found to be in range from 5.6%to 10.6%.According to the SEM analysis,some cracks,pit aspiration and layer decomposition in the micro level of the wood structure were detected.TGA showed that heat treatment makes thermally more stable wood.As a result,it can be said that heat treatment improved the decorative properties of the exotic wood.

Effects of stand types on recreational preferences of society in the Sub-Alpine Zone,northern Turkey

The main objective of this study was to examine how different stand types influenced the tendency of visitors for varying recreational activities(i.e.,hiking,trekking,camping and hunting)from 1993 to 2018 in the surrounding areas of Uluyayla Natural Recreation Site in Bart1n,northern Turkey.A total of 627 visitors were selected on a voluntary basis,and questioned in the form of questionnaire.Most of the participants were in the age of 21-40 years old,and they were mostly(62.4%)male.Most of the participants(82.7%)lived in cities,while 62.8%of them were tourists when visiting the site.In determining the preferences of the visitors regarding the stand types for different recreational activities,several images of each stand were shared with them,and they were asked which stand type they would prefer for a given recreation activity(i.e.,hiking,tracking,camping and hunting).A range of options from 1 to 5 in Likert's scale was used in evaluating the given responses.The degree of positive and negative effects was examined via trend analysis.It was found that stand type had influence on the preferences of visitors regarding the recreational activities.In general,unmanaged and moderately treated stands were more preferred by visitors for the recreational purposes,compared to the previously managed stands.On the other hand,visitors'preference for the activities were different during two periods(i.e.,1993-2005 and 2006-2018).For each recreational activity,there was an increasing trend from 1993 to 2018.There had been a continuous increase for hunting since 1996,and for trekking and camping after 1999.The increases between 1993-1996 and 1996-1999 were likely due to the increasing awareness of the society as a result of the training and consciousness raising activities for nature conservation.The demand on the recreational activities continuously increased in unmanaged and moderately treated stands,while no significant changes were examined in the previously managed stands.The study points out that forest planning and management should consider different needs of visitors for recreational infrastructure.

Analysis of the high-temperature dry sliding behavior of CoCrFeNiTi0.5Alx high-entropy alloys

In this study,CoCrFeNiTi0.5Alx high‐entropy alloys were produced by induction melting and their dry sliding wear behavior was examined at different temperatures.In addition to face‐centered cubic(FCC)phases,low amounts of a tetragonal phase were detected in the microstructures of alloys without Al and microscratches were formed by wear particles on the worn surfaces of the alloy specimens.Two body‐centered cubic(BCC)phases were detected in the alloy with 0.5Al and a fatigue‐related extrusion wear mechanism was detected on the worn surface.The alloy specimen with a high Al content exhibited the best wear characteristics.No wear tracks were formed in single‐phase BCC intermetallic alloys at room temperature and they exhibited a higher wear strength at high temperatures when compared to other samples.