Analysis of temporal changes in land cover and landscape metrics of a managed forest in the west Black Sea region of northern Turkey:1970–2010

Hayati Zengin ·Ahmet Salih Deg˘ermenci ·Pete Bettinger

Introduction

Forest ecosystems ful fill many ecological,economical and socio-cultural functions and provide services at both local and global scales for sustaining human life(Grebner et al.2013).While technical forestry operations aim to move a forest toward an optimal structure based on management objectives,the structure of a forest can also be degraded by unsuccessful management.For example,a failure in regeneration may cause the transformation of desired mixed species stands to pure species stands.In addition,management actions that degrade land resources may cause the extinction of natural vegetation.In Turkey,regeneration for stands with long rotations is often to be completed within 20 years;partial cuttings based on the shade tree system are conducted in different years according to seed productivity and availability of juvenile seedlings.There can be mistakes in the timing of cuttings or treatments because of site conditions that can cause failure of the regeneration process.Regeneration activities that are not completed in a timely manner(within 20 years)can also cause fragmentation of forest areas where some portion of a compartment is regenerated and the rest is not.This can also result in an increase in the number of forest patches covering small areas.

Finally,activities focused only on wood production may cause unsuitable conditions for other ecosystem functions,perhaps by the opening of large areas and the disruption of forest integrity.Forest structure can change due to social pressures from villagers living in or near the forests.Forests can also be degraded or destroyed because of grazing,transhumance in uplands,occupation and settlement,and illegal cuttings.These types of pressure are one of the important factors affecting the temporal change of forest structure in Turkey,where forest villagers represent a large portion of the population.Together with anthropogenic factors,some biotic(e.g.,insects,fungi)and abiotic(e.g.,fire,snow,wind storms)damage may also affect the temporal change of forest structure.Individual and small events of these types at times may not signi ficantly affect stand dynamics;however mass events or large occurrences may have devastating effects on forest conditions.

The evaluation of temporal changes in forests is therefore important in understanding the potential effects of changes in ecosystem services,biological diversity and net productivity,local and regional land degradation,and global warming(Keles¸et al.2007,2016).Land use changes,especially from forest to agriculture,can lead to carbon losses from terrestrial ecosystems(Shrestha et al.2010).The decline of biological diversity is also seen as result of worldwide environmental change.In this regard,habitat losses,fragmentation and decline of habitats are the most important processes.Habitat loss is the destruction of natural vegetation or plant and animal habitats in large areas by human activities(Sivertsen 1995;Plieninger 2006).Fragmentation,which is a relatively subtle process,expresses the segregation of large habitats into smaller and isolated patches.Habitat alteration,which is not a wellstudied subject,occurs when the habitat structure is not changed signi ficantly but ecosystem components have changed or have been extinguished by human effects(Plieninger 2006).The prevention or control of fragmentation,and habitat alteration or loss in forest ecosystems is thus important for protecting biodiversity.Because land use changes are an important issue,researchers have approached it from different points of view.Land use change has recently been assessed with respect to water yield and quality,surface flow and sedimentation,species diversity,protected areas,cadastre studies(Pontius et al.2001;Kimaro et al.2003;Waldhardt et al.2004;Atasoy et al.2005;Verburg et al.2006;Caldas et al.2007;Yu et al.2007;Schindler et al.2008;Inca 2009).

Objectives,constraints,and measures associated with forest-level planning are becoming more complex,as ecological and social goals become as important as economic goals in global and regional scales(Bettinger 2006).The effective management of forests and other natural resources requires the determination of temporal and spatial changes and factors effective by these.Patterns of land cover change may be rather different between regions and countries,within countries,and even within village territories.Comprehending patterns of land cover change,its reasons and possible results,can help managers and policy-makers to develop strategies or solutions to negative consequences that may occur in the future(Bussink and Hijmans 2000).Understanding the in fluential factors can provide substantial information for land-use planning and sustainable management of resources. Furthermore,understanding temporal land-use dynamics,the resulting composition and environmental effects in forest ecosystems makes it possible to de fine trends,understand transitions,and establish a base situation(Keles¸et al.2007).Studies such as these can also assist in the detection of ecological and social impacts related to patterns and development,and in the development of land management policies devoted to sustaining landscape functions(Martín et al.2006).

Ecologists are particularly interested in the spatial distribution of landscape elements because many processes,including climatic factors,seed dispersal,and animal behavior are potentially in fluenced by the patches that comprise a landscape(Hargis et al.1998).Landscape structure,type and con figuration of different landscape elements have important effects not only for the availability of different forest values,but also for various ecosystem functions such as biodiversity,nutrient cycles or water budgets(Baskent 1999).Species diversity generally increases with landscape heterogeneity,yet habitat requirements of species are different and some have different priorities;therefore changesinforeststructuremayhavepositiveeffectsonsome habitat requirements and negative effects on others.For example,some species prefer large,compact habitats of similar forest structure,while others depend on boundary structureslikeaforestedgeorhedges.Thus,whilelandcover changes may lead to an increase of suitable habitats for a species,habitat loss or fragmentation may be a point of concern for others(Holzkamper et al.2005).

It is clear that the in fluence of humans on the landscape hasbeendramaticoverthecourseofthelastcentury.Itisalso clear that methods are needed to properly monitor and evaluate changes in land use/land cover dynamics(Herzog et al.2001).Landscape ecological concepts and applied metrics can be useful in assessing the spatial dimension of sustainable planning(Leitao and Ahern 2002),and from an ecological perspective,landscapes can be investigated and analyzed basedonthe diversityandabundanceofland cover and landscape pattern metrics(Martín et al.2006).A great variety of metrics have been suggested but most of them are complex and their biological meaning is not always clear(Kim and Pauleit 2007),and some are correlated to each other(Uuemaa et al.2009).Certain metrics are appropriate for the patch,patch-type(class)or landscape scale(McGarigal and Marks 1995).A large set of these metrics wasonceinvestigatedbyRiittersetal.(1995)andunderlined the importance of knowledge on statistical and sampling details of most landscape metrics if they are to be used effectively for environmental monitoring.

There are many methods for collecting,analyzing and presenting data related to landscape resources and they are relativelyeasilyaccommodatedbyremotesensingtechniques or geographic information systems(GIS).Their use for determining temporal changes in forest resource conditions has been reported by several authors(Gautam et al.2003;Keles¸etal.2007;Kadiog˘ullariandBas¸kent2008).Theaimof this study is to determine temporal transitions among land cover types and changes in landscape metrics over a 40-year period in a forest planning unit that has been managed under wood production objectives for several years.

Materials and methods

Study site

The Daday Forest Planning Unit(FPU)is located in the center of Kastamonu province in the west Black Sea region of northern Turkey(Fig.1).It lies between 41°28′25′–41°37′06′north latitude and 33°22′17′–33°36′10′east longitude.The altitude is between 800 and 1746 masl.The Kastamonu Regional Directorate of Forestry,which the study area is connected to,is a forest area having an intensive wood production objective for Turkey(a relatively high amount of wood will be extracted from the forest as compared to other areas of the country).The total wood production in the State forests in 2015 was nearly 16.5 million m3with about 8%from Kastamonu province,the only region in which wood production was more than one million m3(1263,954 m3).

The main species are black pine(Pinus nigra)(28.3%),Scots pine(Pinus sylvestris)(16.4%), fir(Abies spp.)(9.7%),oak(Quercus spp.)(10.6%),and oriental beech(Fagus orientalis)(0.3%).Mixed stands of deciduous and coniferous species also cover large areas(34.7%).The forest areas belong to the State and are managed in working circles of 120–180-year rotations,with 20-year harvest cycles.There are forests that may be managed as evenaged or uneven-aged in the planning unit.There are 13 species of mammals and 30 species of birds commonly found in or near the Daday forests(Küc¸ük 2011).The main mammals include European roe deer(Caprealus caprealus),red deer(Cervus elaphus),gray wolf(Canis lupus),red fox(Vulpes vulpes),wild boar(Sus scrofa),European hare(Lepus europaeus),brown bear(Ursus arctos),AsiaMinor ground squirrel(Spermophilus xanthoprymnus)and weasel(Martes spp.).Some bird species include the longlegged buzzard(Buteo ru finus),common kestrel(Falco tinnunculus),peregrine falcon(Falco peregrinus),European turtle dove or wood pigeon(Streptopelia turtur),Eurasian eagle-owl(Bubo bubo)and whitewagtail(Motacilla alba)(Küc¸ük 2011).Water resources,which are very important for wildlife,can become insuf ficient and a problem in dry,summer seasons.

Fig.1 Geographic position of the study area

The Daday town center and 17 villages connected to the town are situated within the forest planning unit.The homes within the villages are arranged in a batch settled(clustered)manner.The population of the whole Daday town is 9481 while the village populations range between 44 and 161(GDF 2010).Since the end of the 1970s,the population has continuously decreased from its high of 18,614,especially as young men have migrated to pursue other labor-related opportunities.The population currently in the area relies heavily on agriculture and animal husbandry for subsistence.

Data collection and analysis

Stand maps prepared for the Daday FPU in 1970,1989,1999 and 2010 were used.In Turkey,forest management plans are renewed every 10 or 20 years and forests are managed toward optimal structure in terms of age or diameter classes.For this,a forest inventory,including land inventory,growing stock and increment inventory,is developed.Through these efforts,the extent of forested and non-forested areas and a map of forest stands are updated periodically.In the context of this study,stand maps constructed in the past by the General Directorate of Forestry were digitized and spatial analyses related to forest structure were performed using ArcGIS 10.4®.The stand maps were prepared based on aerial photographs and field inventories.In these maps,the borders of the settlements were delineated,based on the outline of houses or other structures furthest from the center of each village.Land Cover Types(LCT)related to woodlands,were constructed by grouping individual stands.A number of landscape metrics were calculated for these LCTs using the Patch Analyst 5 extension of the ArcGIS 10.4®software that facilitates the spatial analysis of landscape patches and modeling of attributes associated with patches.

Standmapswere digitizedandstandsymbols on the maps wereregisteredtotheattributetableofthemapsforqueriesby using GIS software.Stand symbols are short and implicit expressions and provide information about tree species and mixtures,development class,and canopy closure of the relatedstand.Standsweredigitizedaspolygons andgrouped under6LCTsasdeciduous(D),coniferous(C),mixed(Mix),degraded or open(DO),agriculture(A),and other(O).Polygons attributed as settlement areas,forest depots,water surfaces,nurseries,mineareas,andorchardsthatoccurredon stand maps at different periods were evaluated as other land cover types.Changes in the areas of LCTs were determined by constructing transition matrixes.A different grouping of LCTswasalsocreatedbasedonstanddevelopmentstages.In thisgrouping,theclasseswereyoung,mature,andoldforest,degraded or open areas,agriculture,and other.Stands with a mean DBH(diameter at breast height)smaller than 8 cm were accepted as the young class.Stands with a mean DBH between8and36 cmwereassumedtoencompassthemature class,and stands with a mean DBH greater than 36 cm were considered old forests.In analyses,while individual forest stands were considered as patches,group of stands based on LCTs or stand development stages were considered as classes.

A number of landscape metrics widely used in the literature were assessed in this study.Class area,number of patches,mean patch size and coef ficient of variation,total edge,edge density,mean patch edge,and mean shape index were of interest,and thus were used as the shape and edge metrics.Explanation of the metrics and the formula used to determine them is presented in Table 1.

Results

Temporal changes in the area of cover types

According to the historical information there were no deciduous forests and land cover types belonging to the other class in 1970.Deciduous areas were created arti ficially by plantation.By transition,456.1 ha of land moved from degraded or open areas,and 14.0 ha from agriculture areas;thus 470.1 ha of deciduous forests were formed by 1989.While there were small transitions,the amount of mixed stands and agricultural areas did not change significantly between 1970 and 1989.Together with these areas,2882.7 ha of coniferous forests in 1970 increased to 4770.9 ha by 1990.The area of degraded and open lands declined from 7033.3 to 4470.9 ha in the same period.Most of the transition from this cover type was to coniferous forests,with an amount of 2004.9 ha.Other transitions amongst cover types between 1970 and 1989 are illustrated in Table 2.

The area of deciduous forests increased 470.1–629.1 ha between the years of 1989 and 1999.In this period there was an 80.5 ha decrease in the area ofconifers(4770.9–4690.4 ha).While there was a 451.2 ha transition from coniferous forests to degraded or open areas,a similar area(448.1 ha)was transformed to conifers from degraded or open areas.Land cover types grouped as other increased nearly two fold and increased from 13.0 to 22.4 ha.

Table 1 Landscape metrics used in the analysis

Table 2 Transition matrix for area(ha)changes among cover types 1970–1989

Transitions among the cover types in 1989–1999 are presented in Table 3.

While the area of deciduous and mixed forests decreased between 1999 and 2010,a 53% (4691.2–7165.3 ha)increase occurred in the area of coniferous forests.During this period,there were transitions from mixed forests(1652.2 ha)and degraded-open areas(1109.2 ha)to coniferous forests.The area of agricultural lands,which was 5284.2 ha in 1990,declined to 4658 ha by the year 2010.Transitions from agriculture were especially related to the increase in coniferous forests and to other land cover type.The latter increased nearly ten-fold from 22.4 to 225.4 hectares.A moderate amount,199.9 ha,was transformed from agriculture to the other cover type,while 13.0 ha transferred vice versa.Transitions among cover types between 1999 and 2010 are presented in Table 4.

In sum,deciduous forests did not exist before 1970 but were created through plantations after 1970,increased to 629.1 ha in 1999,and because of transitions to other land cover types,decreased to 574.4 ha in 2010.The area ofconiferous forests,which was 2882.7 ha in 1970,reached 7165.2 ha in 2010.The area of mixed forests decreased from 1771.4 to 1215.7 ha between 1970 and 2010.The area of degraded and open lands periodically decreased then levelled off at 2973.9 ha in 2010 from 7033.3 ha in 1970.Agricultural lands did not change signi ficantly in the first two periods but then decreased to 4658.0 ha in 2010.The amount of other land areas initially increased slowly and after 1990 jumped with a ten-fold increment to 225.4 ha in 2010.

Table 3 Transition matrix for area(ha)changes among cover types between 1989 and 1999

Table 4 Transition matrix for area(ha)changes among cover types between 1999 and 2010

The temporal changes in the area of different land cover types from one period to the other as a whole is also observable from the maps in Fig.2.

Temporal changes in landscape metrics

Structure,expressed by various landscape metrics of individual stands or the forest ecosystems they constitute,seems to have changed over time.Besides natural factors,management activities are effective by this change.Temporal values of the metrics used to de fine forest structure in this study area are presented in Table 5.

The number of patches(NumP)in the deciduous forest class increased from 19 to 34 between 1999 and 2010 while its class area(CA)decreased over the same period.This means that the mean patch size(MPS)was becoming smaller.Thus,MPS decreased from 33.1 to 16.9 ha during this period of time.While NumP was increasing,patch sizes came closer to each other and became less heterogeneous with patch size coef ficient of variation(PSCoV)decreasing 87.3–68.3%in the period 1999–2010.Because deciduous stands were divided into smaller patches,the total edge(TE)increased,with the value rising from 41.6 to 76.3 km during the period of 1989–2010.This also increased the length of edges per hectare and edge density(ED)reached 4.5 m ha-1in 2010 while it was 2.6 m ha-1in 1989.Because they became smaller patches,the mean patch edge(MPE)also decreased gradually and declined to 2.2 km in 2010.Mean shape index(MSI)was 1.63 in 1989 and 1999 but together with increasing TE,their shapes became more complex and MSI increased to 1.67 in 2010.The area of the deciduous forest class was greater in 2010 than in 1989,but it comprised many more patches.This is an indicator of fragmentation and caused the decline of core area,which decreased from 298.0 to 173.0 ha.A 100 m buffer zone width was used in determining core areas.

Fig.2 Land cover type maps of 1970,1989,1999 and 2010

Both class area and NumP of coniferous forests increased between 1970 and 2010.NumP increased from 256 to 976.MPS gradually became smaller and declined from 11.3 to 7.3 ha.Patch sizes became more heterogeneous and PSCoV was reached as 129%in 2010.TE increased together with CA and NumP and reached 480.3 km in 1970 to 1426.3 km in 2010.There was not much change in the TE value over 1989–1999.In this period,all landscape metrics showed similar values.ED increased from 28.6 to 84.9 m ha-1over 1970–2010,but MPE decreased from 1.9 to 1.5 km.MSI,which was 1.67 in 1970,decreased in the following period but then came to the same level in 2010.The core area of coniferous forests was lower in 2010 relative to 1989 and 1999.This situation was formed by the collective effect of other metrics and shows fragmentation was increased in 2010.

The area of mixed stands decreased from 1771.4 to 1215.7 ha between 1970 and 2010.NumP,which was 113 in 1970,was 196 and 197 in 1989 and 1999,respectively.An increment of NumP,opposite to the slight change in CA,shows there was a decrease in MPS from 15.7 to 9.0 ha between 1970 and 2010.NumP has a value of 100,which decreased signi ficantly from its level of 197 in the previous period.The heterogeneity of patch sizes changed minimally and the PSCoV value declined from 101.2 to 93%,but then increased to 111%in 2010.Depending on the decrease in CA,the TE declined from 256.4 km in 1970 to 191.2 km in 2010.Similarly,there was also a decline in the value of ED,as it decreased from 15.3 to 11.4 m ha-1over the same period.Together with some periodic differences,there was little change in the complexity of patch shapes when 1970 and 2010 values are compared.Finally,there is a signi ficant decrease in the amount of core area,declining from 567.0 ha in 1970 to 96.0 ha in 2010.It is believed that the decrease of CA and NumP,together with increasing fragmentation,led to the decline of the core area.

There was an important decline in the area of degraded or open lands during the 1970–2010 period from 7033.3 to2973.9 ha,and NumP increased in the same period.Depending on transitions to other classes,DO areas were fragmented signi ficantly and as a result the size of core area declined from 3603.0 to 211.0 ha.The same situation may be seen for the agricultural fields.Despite the increase in NumP between 1970 and 2010,the area of agricultural fields declined and this resulted in a reduction of the core area.Between 1999 and 2010,the area of this class increased ten-fold and reached 225.4 from 22.4 ha.Because this area consists of numerous small patches,the amount of core area was not increased proportionally with class area and remained unchanged.NumP increased from 2 to 80 during this period.This was also resulted in an increase in the edge metrics.

Table 5 Periodic changes in the values of landscape metrics between 1970 and 2010

Compared with 1970,only the NumP of mixed forests had decreased by 2010,but NumP increased for the other classes.In addition to the NumP of degraded or open areas and agricultural lands increasing,the area of these classes also decreased.MPS of all classes decreased,resulting in smaller patches.While the heterogeneity of patch sizes of deciduous forests decreased,heterogeneity increased in other classes.Despite TE decreasing in mixed forests,it increased for all other classes.Based on MSI values,the shape of patches in forested lands(deciduous,coniferous or mixed)is simpler than in the other classes.While the quantity of core area in deciduous and coniferous classes is higher in 2010 relative to 1970,its value decreased,especially for the coniferous class.The core area of degraded or open areas and agricultural lands also diminished relative to their value in 1970.Shannon’s Diversity Index was decreased to the value of 1.39 in 2010 from 2.67 in 1970.Shannon’s Diversity Index is at the landscape level and is a relative measure of patch diversity.The Index will equal to zero when there is only one patch in the landscape and increases as the number of patch types or proportional distribution of patch types increases.It is used as a measure of number of cover types and abundance of number of patches belong to these cover types.The number of cover types in the area is constant as six(deciduous,coniferous,mixed,degraded or open,agriculture and other).So,the change in the abundance of patches at different periods can affect the Shannon value.The decrease in the value of Shannon index in 2010 can be explained by the dominance of some cover types as number of patch types in the area.The increase of NumP value of coniferous from 256 to 976 made it dominant and caused a decrease in the value of diversity index.

Another analysis was carried out based on stand development ages.Temporal values obtained based on these analysis are given in Table 6.

While there were not any young forests in the study area in 1970,1228.2 ha were established by 1989 through the regeneration of old stands.Because of the transition of some areas to the mature class and to lesser amounts of regeneration,the area of the young class decreased to 686.8 ha in 1999.However,it reached 1829.6 ha in 2010.In accordance with the previous period,NumP in 1999 decreased,possibly because the regeneration of stands achieved in small patches increased in value to 108 in 2010.This can also be seen from MPS values which were getting smaller periodically.The PSCoV value increased to 89.5%in 2010 based on an increased in heterogeneity through smaller patch sizes.TE and ED values increased in relation with increased class areas.Also,MPE decreased based on descending MPS values.There were not any discernible changes in MSI values which represent the complexity of patch shapes.The core area for young forests indicates a rise and fall over time that is based on class areas.

The area of mature forests was 2980 ha in 1970,increased during the next period,and then declined to 2708.1 ha in 2010.The reason for this was the transition between classes by the development rate of stands over time.Because the forest was initially not in an optimal structure,these transitions were irregular.Based on class areas,NumP changed and MPS generally declined periodically.This also resulted in the decline in the MPE of mature stands.There is a signi ficant decrease in the amount of core area(395.8–82.5 ha)of this class between 1970 and 2010.

While there were not many changes in the class of older forests between 1970 and 1999,they reached 4448.2 ha in 2010.Because of the transition of some stands from the mature class to the older class,class area increased during the last period of the analysis.Similarly,NumP,TE,ED and core area values increased in this period.MPS decreased,however.

In the landscape scale,NumP increased nearly twofold,and land areas fragmented into smaller patches between 1970 and 2010.This led to increases in TE and MPE values.MSI values show that the patches had irregular shapes and with the exception of the first period,their value did not change.This is because forest management is generally based on natural borders of stands and land managers try not to change them too much.Together with factors sourced from some metrics like number of patches,mean patch size and total edge,changes in land cover increased the fragmentation at the landscape scale,which resulted in a decrease in core area between 1970 and 2010.Shannon’s Diversity Index increased periodically and reached a value of 1.6 in 2010 from 1.26 in 1970.

Table 6 Periodic changes in the values of landscape metrics for stand development ages between 1970 and 2010

Discussion

Forested areas have increased incrementally in the Daday FPU between 1970 and 2010.The proportion of productive forests was 27.7%in 1970 and this increased to 41.5,42.2 and 53.3%in 1989,1999 and 2010,respectively.Migration of people from villages to large cities can also be observed in study area,and this is thought to have a positive effect on the reduction of social pressures on these forests.Especially after the 1970s,the period that this analysis begins,the population has continuously decreased from about 18,600 to today’s level of nearly half of this because of migration(mostly by young people).The rest of the population(mainly older)is involved in animal husbandry,and the pressures on forested areas are much less than before.

Compared with 1970,areas of deciduous and coniferous forests,and areas in the other land class have increased by 2010.It is interesting to note that while young people have migrated to large cities,the settlement areas have grown larger due to new houses and other buildings.Hence,the ratio of the number of people per house has become smaller.The management of forests may have caused the decline of mixed forests and some parts of the planning unit as these were transformed to pure stands of coniferous or deciduous species.The amount of land in the degraded or open area classes and the agriculture class has declined,yet the number of patches for these classes has increased.It is believed that the reason for this is the rehabilitation of degraded or open areas or the transitions from the agriculture class to others because of settlements or afforestation efforts.

The reasons for changes in the landscape vary but many are due to efforts to organize and make ef ficient the forest resources through management activities.Mean patch size values decreased in all land classes over the period of the study,and thus the forest has become more fragmented and now consists of a larger collection of smaller patches.Interestingly,the heterogeneity of patch sizes decreased in the deciduous class while other classes became more heterogeneous in terms of size.This implies that the deciduous forest stands are becoming less variable in size,while the other classes are becoming more variable.The patch size coef ficient of variation for deciduous areas also decreased due to the transition of areas having extreme sizes in this class to other intermediate sizes between 1990 and 2010.And while total edge declined in the mixed forests,it showed an increase in all other classes,suggesting that patches of certain forested lands(coniferous,deciduous and mixed)have become simpler in shape over the last 40 years through management.Interestingly,based simply on the mean shape index values,the shapes of the agriculture and degraded or open class areas have become more complex.While the amount of core forest area was higher in coniferous and deciduous classes in 2010 than in the past,this has declined signi ficantly for the mixed forest class,perhaps due to transitions to homogenous forest types.It is also thought that implementing a shade tree system of regeneration instead of clear-cutting in the management of deciduous forests may cause higher mean patch size and mean patch edge in the deciduous than in the coniferous forest class.

However,in general,the core area of old forests has increased over time,and the regeneration of stands that began in 1970 has increased the diversity in terms of age classes.Besides increased patchiness,an increment in forest fragmentation at the landscape scale caused a decline of core areas in all other classes relative to 1970.

In the Daday FPU,the amount of old forests covered nearly half the total productive forest area(4448 of 8986 ha)in 2010.However,the planned timber production levels are not much different from the previous period(nearly 18,000 m3per year),even though the forestry vision changed and ecosystem-based functional planning was adopted.In managing these forests,a variety of ecosystem services are considered,and in the 2010–2029 forest management plan together with wood production,erosion control,public health,aesthetics,ecotourism and recreation will be amongst the management objectives.From a production services standpoint,the amount of timber produced has to be also considered while managing the forests.Yet,while the study area is within a region with high potential for intensive wood production in terms of old forest area,it also has an important role in wildlife habitat and other ecosystem functions.Old forest structure is perceived as more suitable in terms of public health,aesthetics,ecotourism,and recreation.This is why the amount of scheduled allowable cuts is less than the total volume increment of these forests.However,a large amount of timber was produced during the 1989–2008 period through unregulated felling because of wind and insect damage.In some years the harvest was more than 10,000 cubic meters.In addition to fires that occur,it is not possible to foresee these kinds of disturbances and address them in forest management plans.Some protection measures can be suggested,such as regulating regeneration activities based on the predominant wind direction or encouraging the development of mixed species stands by lowering the amount of allowable cut.

Wildlife habitat models can be developed as new theories regarding the use of the landscape by various species are presented,the appropriate data are collected,and species–habitat relationships are modeled(Bettinger 2006).Habitat requirements of some fauna in the study area vary.Roe deer(Caprealus caprealus),for example,live in young,mixed forests where there are agriculture and pasture lands,and tend to avoid pure coniferous or deciduous forests.Wolves(Canis lupus)desire deciduous or coniferous forests,shrubs and steppes.Black bears(Ursus arctos)prefer less accessible dense areas and old growth forests.Further,habitat diversity,in terms of vertical and horizontal forest structure,can positively affect the richness of songbird populations(Küc¸ük 2011).The decline of mixed forests and the increase of coniferous forests may have unfavorable effects on the range of roe deer,while young forests can provide improved habitats.The increase in deciduous and coniferous forests can provide better landscape conditions for wolves,but an increase in the core area of old forests can be important for large mammals like bears.Generally,with a decline of mean patch sizes,the associated increase in edge and structural diversity can lead to improvements in songbird diversity.

Conclusions

Forests are dynamic systems and their structure can change through planned activities and other natural or human disturbances.If we can understand the interactions between forest structure and ecosystem services,we can design the future forest and guide its development through the use of management activities that are based on our objectives.Landscape metrics can be good criteria for evaluating forest structure in terms their suitability for forest functions,but the relationships among structure,landscape metrics,and services that people demand from the forest are often unclear.

In this study we concentrated on simplistic analyses of changes in habitat and metrics through time.Because the species–habitat relationships are not clear,we cannot proceed further with the analysis.Planners can adjust the percent of a landscape in each land cover class or control the level of metrics during each planning period and thus adjust the landscape’s suitability for different ecosystem services.

In Turkey,forest management and planning is progressing in a way that integrates forest functions into the planning process,and thus the country has adopted the concept of ecosystem-based functional planning in management of all forests.Besides wood production,this process requires other data and information on ecological relationships among various ecosystem services.Therefore,there are research needs that require investigation into the relationships between forest structure,landscape metrics,and ecosystem services,and these gaps currently limit the scope ofthe analyses ofmanagementeffects on spatiotemporal dynamics of forest ecosystems that can be performed.

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