The paper presents the influence of impression methods, polymer materials, and implant angulation on the accuracy of the definitive working model for the production of implant-supported dental restorations, based on the analysis of results obtained using different impression methods, materials, and parallel and angulated implants. The study findings indicate that all aforementioned factors impact the accuracy of the definitive working model. Specifically, 20° implant angulation in relation to the vertical plane has a greater impact on the impression accuracy compared to parallel implants. The open and splint method in combination with addition silicone, as well as the splint method and polyether combination yielded more accurate results when using implants under 20° angulation compared to other method and material combinations. The splint method in combination with addition silicone resulted in the smallest mean deviations from the center of the parallel implant base compared to other combinations of methods and materials. Analysis results further revealed statistically significant differences in the measured indicators across impression methods, implants, and polymer materials. Owing to the technological advancements in the medical field, and the extensive research-based evidence confirming the effectiveness of implant prosthetics, this scientific and clinical discipline has gained popularity in recent decades . Meta reImplant-supported dental restorations that are produced by the conventional method are made indirectly, on a model that should faithfully reproduce the morphology, position, and interrelationships of the remaining teeth, implants, residual alveolar ridges, and surrounding soft tissues . ClinicaAn ample body of research confirmed that screw-retained restorations carry a greater risk of complications, primarily of a technical nature, such as crew loosening or loss, fractures in the aesthetic part of the restoration due to reduced occlusal surface, screw location in an unfavorable location, mesostructure fractures, etc. ,8,9. In Accurate and precise impression is the most important link in the chain of prosthetic rehabilitation of the stomatognathic system with the help of implant-supported dental restorations. This clinical procedure in the construction of superstructures on implants has a direct impact on the relationship between implant-supported restorations and abutments ,11.A highly pertinent topic in this context is the loading and adaptation of implants and peri-implant tissue to the stresses that arise as a result of the orofacial system functions. Many factors can affect the behavior of the implant and the receiving region, such as surgeon experience , and areThe objective of the present study is to contribute to this line of research by providing a strategy for producing a more accurate definitive working model, and thus a better fit between the prosthetic superstructures and implants. As a part of this work, a methodology that can be used for obtaining impressions of both substructures (teeth and implants) in a single phase is demonstrated by applying it to a specific clinical case, along with determining the degree of deviations that should not jeopardize the reconstruction longevity. Moreover, for both parallel and angulated implants, in addition to geometrical analysis of teeth-abutments by CAD inspection and measurement of spatial deviations of the implant base from the implant center on the nominal model (linear deviation), analysis of the geometrical deviation between the scanned implant lateral axis and the nominal master model (angular deviation) was performed.The research reported here was performed according to the workflow shown in ® M-BEGO, Germany), using a 4° carbide conical cutter in order to ensure the parallelism of the abutment teeth, and subsequently the demarcation step was finished on each abutment using a special drill from the set with a flat tip and a diameter of 1 mm and a high-speed water-cooled drill , manually. Next, with the help of the so-called “Angulation key”, on the one side of the edentulous region, implants were positioned parallel to each other and perpendicular to the horizontal plane, while ensuring their convergence on the other side by situating them at a 20° angle to the vertical plane . At the end of master model fabrication the prepared front teeth , since the material from which the master model was made is brittle, the abutments were shortened to a level of 4–5 mm above the demarcation step to prevent breakage during many impressions, and in order to obtain a good impression of the abutment around the demarcation zone and just above which required exceptional accuracy for fitting the future ceramic restoration. That area was subsequently subjected to CAD inspection for each abutment individually.The reference master model was designed to mimic the very common clinical situation of partial edentulism (Kennedy Class I) in the upper jaw, with presented central incisors and canines , which is an indication for the placement of two implants in the posterior region of both sides of the jaw to complete the dental arch. In such clinical conditions, the regions selected for implant placement are most often the first premolar and first molar teeth regions, because often anatomical conditions, such as a low maxillary sinus floor, do not allow placement of a distal implant in the second molar region without prior surgical intervention. The remaining teeth were prepared to accept the ceramic front bridge (range 13–23), while two implants were installed in the lateral edentulous areas on each side in the region of the first premolar  and the first molar . On one side, the longitudinal axes of both implants were parallel and perpendicular to the horizontal plane, while on the opposite side, the anterior and the posterior implants were positioned at a 20° angle to the vertical plane , to ensure their convergence. The model was produced by casting a factory mold of the maxilla model with full dentition in hard plaster (type 3), which was subsequently remodeled by cutting all teeth except the central incisors and canines into a model that mimics the given clinical case of partial edentulousness. For more facile processing of the remaining teeth and subsequent digitization, the adapted model was replicated in polyurethane resin . Tooth preparation was performed using a special set  respecting all the principles of tooth preparation for ceramic crowns. At the very beginning, the teeth were prepared in a parallelometer  were used. These laboratory scanners were used because they have very similar scanning characteristics, primarily in scanning accuracy (less than 10 µm). Master model scanning resulted in two virtual master models that were later compared with the scanned replica models. For gathering data on the spatial orientation of the implants and subsequent deviation analysis, scanning abutments (Scan bodies) specifically designed for this purpose were employed a. FigureIn this phase, impressions of the master models were obtained using standard perforated tray and irreversible hydrocolloid  to allow the preliminary working models to be cast. Based on the impressions taken with the irreversible hydrocolloid, the two preliminary models in hard plaster were cast-type 3 . On these preliminary models, individual trays (3 closed and 6 open) were made using thermoplastic acrylic foil , for the purposes of producing definitive impressions, which are shown in For definitive impressions, impression accuracy was assessed using three main control groups—tooth abutments on the master model, angulated implants on the master model, and parallel implants on the master model—each comprising samples obtained by 3D digitization using two 3D scanners.Two types of polymer impression-taking materials were used, addition silicone/polyvinyl siloxane-PVS  and polyether-PE . In total, 30 master model impressions were produced (10 for each of the aforementioned methods), and all impressions were taken at the implant level. Depending on the technique performed, the appropriate manufacturer-supplied tools were used. ®, Tissue level, Regular neck, synOcta open-tray impression cap, with integral guide screw, red), as shown in For the direct methods with and without transfer splinting, transfers corresponding to the implant types from the original manufacturers’ sets were used   a–c.Impressions were performed by the same therapist throughout the whole experiment, during which the pressure and removal force were approximated by the therapist’s tactile sensitivity method, in order to mimic the clinical conditions of taking impressions in implant prosthetics as closely as possible.®, Japan). Thirty definitive working models with embedded implant body analogs were obtained for experimental 3D digitization and further deviation analysis  and experimental 3D models. The tooth abutments were denoted with the symbol T1, T2, T3, and T4, while “I” was chosen for the implant abutments, whereby angular implants were labeled I1 and I2, and parallel implants I3 and I4 .In the geometrical analysis of implants, the master model was used to analyze the deviations in scanned experimental 3D models obtained by different impression methods. Since the master model itself was obtained by 3D scanning, the base positions of the angulated and parallel implants could not be determined definitively. To ascertain the exact position of the implant base and enable accurate comparison and analysis of deviations on the experimental 3D models, implant 3D model was imported from the Straumann library and was superimposed on the master model using the best-fit method. This method consists of finding common points between the master 3D model and implant 3D model and aligning their geometry using iterative closest point (ICP) algorithm. The import and positioning procedure was repeated for all implants a. A locaBy establishing the local coordinate system, the deviation of the center of the experimental 3D model base could be examined in relation to the origin of the corresponding local coordinate system of the master model. The analysis included deviations in the directions of all three axes , as well as the shortest distance between the base center and the local coordinate origin , as shown in When analyzing the experimental model deviations, superimposition was also necessary to ensure their correct alignment with the virtual master model. The best-fit method was also used for this purpose . The samp < 0.05 was taken as the threshold of statistical significance. Determination of statistically significant differences of deviations from the center and the angle of implant deviations was analyzed using Multivariate Analysis of Variance (MANOVA) and Analysis of Variance (ANOVA) for all combinations of methods, implants, and materials.Based on all data yielded by the dimensional analysis, a database was created, which was processed for the purpose of statistical analysis by applying the SPSS 20.0 commercial software. In this work, the aim was to establish existence of any statistically significant differences among the relevant misalignment indicators depending on the impression methods, implants, and materials used. In all analyses, In the CAD inspection of the tooth abutments, the zone of step transition (demarcation zone) was analyzed for each abutment individually a,b. The As this analysis resulted in an extensive dataset, Taking into account the method adopted for measuring the deviation of the implant base and the lateral axis of the scanned implant, shown in Due to the large volume of acquired data, and with the aim of grouping the results, the analysis initially focused on the differences arising between the use of two 3D scanners. As several results from  had outlp = 0.565. This finding statistically justified the exclusion of 3D scanner as a grouping variable, allowing the aggregation of data from both scanners prior to further analysis. The groups were thus divided into subgroups, based on the comparisons performed as a part of this research:Three groups based on the applied impression method ,Two groups based on implant type ,Two groups based on the impression material (additive silicone/PVS and polyether/PE).After the preliminary analysis, 3D scanner accuracy was subjected to the multivariate analysis of variance. The results revealed absence of statistically significant differences in the linear and angular deviations between the two scanners F = 0.572; A graphical representation of the distribution of values obtained for the linear and angular deviation, according to the previously defined groups, is shown in As evident from It is evident from Based on The preliminary data processing of the results related to the deviation of the scanned tooth abutment surfaces also included a comparative analysis of the measurements obtained by both 3D scanners, in order to enable the aggregation of data related to all analyzed samples. The values included in the analysis of scanned abutments were the maximum and minimum deviation, i.e., their mean value (mean absolute deviation). p = 0.033, and F = 7.271, p = 0.008, respectively. The interaction between the method and the material also proved to be statistically significant, with F = 9.739, p < 0.001. When a pairwise comparison was performed, statistically significant differences between closed and open methods (p = 0.012) and closed and splint methods (p = 0.007) also emerged. Specifically, the mean absolute deviation related to the closed method was statistically significantly larger than that obtained for the other two methods  = 3.452,  methods .As the acceptable misalignment between the finished implant-supported restoration and the abutment has not been scientifically quantified, no limit for the detected deviations was set in the present study, and all measurements were included in the statistical analysis. Namely, the boundaries set by various researchers for the measured deviation values, considering the values below the set limit to be biologically tolerable, range from 10 μm to 150 μm, and were chosen arbitrarily, guided by the empirical evidence regarding the degree of inaccuracy that would not cause complications ,24. The Analysis of the three impression methods revealed that the application of the splint impression method resulted in the smallest mean deviations from the center of the implant base compared to the open method without transfer splinting and the closed click method, which yielded comparable results. Moreover, findings yielded by analyzing the mean angle of deviation indicated that the splint method was most accurate, while the accuracy of the remaining two methods was comparable. The same conclusions were reported by Stimmelmayr et al., for the placement of four implants in edentulous jaws in several studies ,27,28. THowever, it is impossible to directly compare the findings obtained in the aforementioned investigations due to the differences in the implant type, number and angulation, as well as the research methodology, the impression surface accuracy assessment method, etc. The present study is original because of the presence of tooth abutments in the frontal part of the arch, as well as the extreme angulation and mutual convergence of the implants on one side.Moreover, a significant difference in the results obtained for the implant groups was also noted, and impressions involving parallel implants were more accurate, confirming the necessity of surgical guides during implantation, in order to achieve a better-fitting restoration and improve its durability. When analyzing the data obtained by measuring the linear deviation in this comparison group, there was no statistically significant difference between angulated and parallel implants.The analyses further revealed that implant angulation, which was adopted in the present study to facilitate comparison with parallel implants, affects the positioning of supragingival part of the implant on the replica model, which in the further course of restoration can lead to greater discrepancies between the restoration and abutment. This finding supports the evidence provided by many researchers indicating that the use of non-parallel implants adversely affects the impression accuracy ,33,39,40By comparing the implant impressions obtained using addition silicone (PVS) and polyether (PE), PVS was found to result in a statistically significantly lower mean linear as well as angular deviation. These observations are in line with the results reported by Sorrentino (2010), Kurtulmus-Yilmaz (2014), and Vojdani (2015) ,44,45. TAs the two main groups comprised of three subgroups  and one had two subgroups (the implant group), the total number of all possible combinations was 12. Thus, individual analyses were also performed for each of the measured parameters, for all possible group combinations. The findings indicated that in the angulated implant group, for the mean linear deviation, the combinations involving the open method, splint, and closed method with addition silicone yielded statistically significantly smaller deviations compared to other combinations, while there was no statistically significant difference among these three combinations.This result also explains the absence of statistically significant differences between angulated and parallel implants in terms of the deviation from the center of the implant axis. The mean angular deviation values for the angulated implant group differed in relation to the linear deviation. When this parameter was analyzed for this group of implants, the splint and open method in combination with addition silicone, and the splint method in combination with polyether yielded the most accurate results, without statistically significant differences between them.A conclusion that can be reached with certainty from these findings is that PVS application resulted in the smallest deviations in both parameters in the angulated implant group. These results indicate that in the clinical case presented in this work, either open or splint impression method using addition silicone would be appropriate, because this material was shown to be most reliable.These assertions are supported by the findings reported by Sorrentino and colleagues  indicatiThe closed method/addition silicone combination, which was characterized by similar accuracy in terms of linear deviation, cannot be recommended with certainty for implants of this angulation, as it produced significantly larger discrepancies in the mean angular deviation. This issue was likely caused by the movement in the transporters themselves when separating the impression from the imprinted surfaces, which resulted in greater discrepancies in the coronary parts than in the gingival parts that rest on the implant neck. As the splint method produced the smallest overall deviations in both measured parameters, and stood out as one of the most accurate in the group of angulated implants, which is also true for PVS material; it can be concluded that this combination of method and material is the right choice for implants with 20° angulation with respect to the vertical plane. In the group of parallel implants, the splint method in combination with PVS material resulted in statistically significantly smaller discrepancies in the average deviation from the implant axis center compared to all other combinations, which again points to the previous conclusion that the splint method/PVS material is the most accurate combination for both parallel and non-parallel implants . In contThus, considering the values of both observed parameters for the parallel implant group, it can be concluded that the splint method in combination with PVS is a good choice for transferring the position of the implant body to the definitive working model, and that the combination of method and material does not affect the average deviation angle, with the exception of the aforementioned combination which produced the largest discrepancies. Although the findings obtained for the open/PE combination might be due to the reasons suggested above, they could have arisen as a result of errors during the printing phase or digitization process, which precludes any definitive conclusions about the complete inferiority of this combination relative to other combinations of methods and materials examined here.Most studies on the implant prosthetics impression accuracy are performed in vitro, which carries the risk of the results obtained being influenced by a wide range of parameters related to the experiment that may be difficult to control. In addition, as there is no widely accepted protocol or methodology to guide the researchers, reaching consensus on the accuracy of methods and materials for a particular implant type, number, and angulation based on the obtained findings is extremely challenging. Therefore, in vitro methodologies for assessing the impression accuracy have numerous advantages, because all aggravating factors that exist in the oral cavity and can affect the impression accuracy can be avoided. The extenuating conditions, such as humid environment and difficult manipulation in the mouth, in addition to the above factors that make a clinical research method on this topic difficult to implement, may increase the likelihood of errors in in vivo impression-making process, thus reducing the accuracy of the final model compared to that obtained under in vitro conditions.This justifies the decision made in this study to include in the analysis deviation parameters pertaining to the real surfaces of the master model, as in vitro measurements are, on average, expected to produce smaller misalignments than those attainable under clinical conditions. The conclusions drawn from all possible combinations of the main groups compared in this study provide additional information on the impact of the applied method and impression material for parallel and non-parallel implants on the accuracy of the definitive working model used in the design of implant-supported restorations. This, in turn, may facilitate the selection of an adequate method for producing implants that for whatever reason, need to converge with each other under extreme angulations, as well as for ideally parallel implants.As a part of this study, we also examined the joint influence of the impression method and material on the accuracy of the imprinted surfaces of tooth abutments in the frontal part of edentulous maxilla during simultaneous impression for a given clinical case. The same analytical approach as for the implants was adopted to assess the resulting deviations. The preliminary data processing also confirmed that the two scanners employed in this work yielded consistent results, allowing the information obtained in both cases to be merged into a single dataset. Therefore, in the subsequent analysis, mean absolute deviation in the demarcation zone in relation to the nominal geometry was adopted. Overall, our findings indicate that splint and open method yielded comparable results, while producing statistically significantly smaller mean absolute deviations compared to the closed impression method. With respect to the same parameter, PVS was superior to PE.Consequently, it may be advisable to use addition silicones rather than other polymer impression materials in the reproduction of surfaces captured by impressions, as suggested by other authors ,47. HoweBased on the results obtained in this work, it can be concluded that the impression method, implant angulation, and the impression material type affect the accuracy of the definitive working model used for the production of implant-supported dental restorations. On basis of the research presented, it can be concluded that the split method, in combination with addition silicone, could be the combination of choice for the clinical case, because in total it had the smallest deviations and stood out as the most accurate. Additionally, the closed impression technique was the most inaccurate, especially in combination with polyether materials and angulated group of implants. With all this in mind, one of the directions of future research will be to deal in depth with polymer characteristics and their influence on clinical outcome.Moreover, owing to the rapid technological advances in the production of prosthetic restorations, which involves the application of a completely digital production flow, future research will also include a comparison of the accuracy of intraoral digital impressions and the latest modified conventional impression techniques, all with the aim of obtaining the most accurate definitive working model and thus a more accurate fit of the prosthetic superstructure.


Eucalyptus hotspot highlands of northwestern Ethiopia, where this study was carried out, provides services that are essential to changes in the life of the society and biodiversity. However, in recent years, the ecosystem is facing a serious threat from intensive monoculture plantations of Eucalyptus. This has resulted in transformation of the cultural landscapes and a loss of biodiversity. The problem in turn calls for designing appropriate ecological improvement programs. Thus, the current study examined the preferences of residents concerning this area and estimated their willingness to pay (WTP) for the proposed ecosystem improvement programs using a Choice Experiment approach. Data were aggregated from 388 residents using a questionnaire survey in January 2020. The survey contained ecological improvement schemes and a hypothetical event by which respondents expressed their willingness to pay a yearly utility fee as a compensation for the improvement programs. Results showed significant differences in resident preferences towards the proposed ecological improvement attributes. The findings also indicated that the socioeconomic backgrounds of residents contributed for the heterogeneity in their WTP for ecological improvement schemes. Accordingly, the marginal willingness to pay of residents was USD 205/person/year for the respective ecological improvement attributes. The findings suggest that policy makers should consider such attribute-based public preferences while planning landscape development and conservation programs. This study can provide vital policy implications and contribute to knowledge as it presents how the non-market valuations of ecosystems help maximize social welfare.Today, evaluating ecological wellbeing and ecosystem services is becoming a great concern towards conserving the natural resource base. Healthy functioning ecosystems have fundamental roles for aiding humankind to lead a healthy life and ensure an improved social welfare. Estimating the non-market benefits of ecosystem services can help experts and the public frame policy directions designed for landscape development. The ecosystem of the  Eucalyptus that sustain the livelihood of smallholder growers. Increasing population together with intensive traditional farming has resulted in degradation of the natural environment. The decline in productivity of crop lands has aggravated the rapid conversion of crop lands and pushed farmers to shift to plantation growing of the most rewarding tree genera, Eucalyptus. Today, Eucalyptus is among the most economically important for short rotation plantations as an option tree for biomass and fiber production [Eucalyptus was introduced to Ethiopia in the second half of the 19th century for the rising demands of forest products for construction and fuel [The northwestern highlands of Ethiopia have a dynamic ecosystem, which experiences intensive farming practices involving cultivation of food crops and plantations of oduction ,2. Eucaland fuel .Eucalyptus in Ethiopia. The first and most prominent reason is the absence of native tree species that can be grown alternatively with equivalent economic contributions similar to Eucalyptus. Indigenous and other exotic forest stands, such as Cordia africana, Juniperus procera, Podocarpus falcatus, Olea europaea, Acacia dicurens, and Cupressus species, have limited growth and production capacity compared to Eucalyptus [Eucalyptus use, is its vigorous growing habit, high potential for coppicing, high yielding potential in short rotations, and the provision of fiber and energy sources suitable for a variety of uses [There are different reasons for the expansion of calyptus . Another of uses ,6,7,8. T of uses ,10 and h of uses ,12,13, t of uses .Eucalyptus also depletes ground water, which aggravates watershed degradation [Eucalyptus a highly productive crop may contribute to its potential to be an invasive species [Eucalyptus globulus is the most widely grown and well-adapted non-native tree species in the study area. Non-native species have the potential to influence the composition, structure, and function of ecosystems where they are introduced [Eucalyptus are capable of invading ecosystems across the world [Eucalyptus globulus has been introduced and become established in five different countries with climates ranging from shrub lands to forests and resulted in the understory exhibiting decreased height and species richness [Despite its economic and social benefits, there is a growing concern regarding the negative ecological attributes and invasive nature of the tree, which can be considered as one of the greatest threats to biodiversity and the provision of valuable ecosystem services . Differeradation . Differe species . Eucalyptroduced ,21, and he world ,23. Eucarichness .of Eucalyptus and its expansion as a monoculture plantation. The introduction of Eucalyptus, as an alien genus to a new area, has serious invasion risks on biodiversity and ecosystem. Forstmaier et al. [Eucalyptus and its invasive behavior on the ecological wellbeing. Various studies have also reported the negative impact of Eucalyptus on soil and biodiversity, with evidence that Eucalyptus can drain water resources, aggravate soil erosion, suppress undergrowth, deplete soil nutrients, and induce allelopathic effects [Eucalyptus has allelopathic effects around the root zones of the neighboring crops and ecological impacts due to its shading effect under and near the tree canopy. A study by Lopez [Eucalyptus globulus, which resulted in reduction in biological diversity due to the displacement of native plants and wildlife habitats. Teketay [Eucalyptus plantations than in indigenous forest stands.Aside from the economic and social benefits, there are scientific debates regarding the negative ecological impacts r et al.  reported effects . Studies effects ,17,18 haby Lopez  has repo Teketay  has alsoEucalyptus plantations exposing ecosystem vulnerability and challenges to the long-term ecological sustainability. Ongoing land degradation, climate change, ocean acidification, and land cover changes are reducing the quantity and quality of ecosystem services being provided globally [Given the positive economic attributes and negative ecological impacts of the tree, the natural forests in these areas have been eliminated and replaced with a monoculture of globally . A studyglobally  showed tglobally  also indEucalyptus hotspot highlands of northwestern Ethiopia has been disturbed. This includes a near to complete replacement of the natural forests, conversion of crop lands to Eucalyptus plantations, and the establishment of a monoculture Eucalyptus plantation over most of the area. This apparently threatens the existing natural ecosystem that has provisioning, regulating, cultural, and supporting services [Practical evidence shows that the ecosystem of the services .Eucalyptus would be of paramount importance. Natural resource management interventions by rational land use strategies are very important to control the rapid expansion of Eucalyptus, which can pose burdens on ecological wellbeing. In addition, it would be very important to estimate the economic value of restricted plantation areas of Eucalyptus and residents’ willingness to pay for the designed ecological improvement programs in the study area. It is possible to estimate the non-market benefits of restricting the expansion of Eucalyptus in economic terms and to examine the possible directions for supporting the conservation of ecological biodiversity that are preferred by people in the conservation strategy.To restore the natural ecosystem in the study area with Pareto efficiency land resource management, designing improvement programs for the restricted plantation of Eucalyptus hotspot highlands of the Northwestern Ethiopia and identify values on this basis.We employed a Choice Experiment (CE) method, which was selected as the most suitable technique to analyze people’s choice for its wide application for valuing environmental goods and services. The CE method is appropriate for analyzing choice to exploit the The method has already been successfully applied in many different wetland settings and has the advantage of being able to generate multiple value estimates from a single application. Many scholars ,32,33 haEucalyptus plantations in the Eucalyptus hotspot highlands of northwestern Ethiopia would impact the ecological wellbeing and that these ecological challenges can be overcome through designing appropriate ecological management programs. Hence, the main aim of this study was to contribute to these ecological improvement programs through estimating the economic value of restricted plantation areas of Eucalyptus in the study region. In addition, the study was intended to estimate residents’ willingness to pay for the ecological improvement schemes. The study presents policy suggestions for addressing the challenges to ecology and biodiversity due to the establishment of Eucalyptus monoculture plantations. It also provides rational strategies to policy makers for the possibility of ensuring the ecological sustainability and biodiversity conservation in the study area. In contrast to studies including [Eucalyptus. However, using the same approach as for the restriction of such invasive species was taken as a good opportunity and exception for this study. Good awareness of most of the respondents to the negative impact of Eucalyptus is another opportunity. The problem, however, demands continuous policy efforts for ensuring ecological wellbeing and biodiversity conservation.The study hypothesized that the expansion of areas of monoculture ncluding ,33,35, wEucalyptus hotspot highlands of northwestern Ethiopia , wheat, potato, barley, and beans. Eucalyptus globulus is the widely planted species for monoculture plantations in the study area [In terms of ecological setup, the area is characterized by distinct landscape features with slopes ranging from nearly flat to very steep (greater than 45%). Most of the land is used for the cultivation of food crops, while monoculture udy area .Choice modeling is a popularly applied technique in various fields for estimating the passive use value of environmental goods. It is a random utility model that can be used to explore the marginal willingness to pay for all the attributes and levels . The tecMcFadden  defined A CE has many advantages over the contingent valuation method. It is easier to estimate the value of the individual attributes that make up an environmental good. In the contingent valuation method (CVM), the value of individual characteristics of the good will not be estimated and thus estimation is made for the environmental good or services as a whole ,43. A CEA CE also avoids the limited choice problem of the dichotomous choice design in the CVM, as respondents are not faced with the stark “all or nothing” choice. They may choose one of two environmental alternatives. Thus, in a CE design, there are repeated opportunities for them to express their environmental preferences.The use of the choice experiment method is a model of consumer choice following the works of Lancaster  and the j from option i, i for consumer jj from option i [According to this theory, individuals are assumed to make choices based on the attributes of the alternatives with some degree of randomness . Random option i .In CE, where the respondent is asked to choose the most preferred among a set of alternatives, random utility theory can be used to model the choices as a function of attributes and attribute levels. The RUT thus, provides a link between the deterministic model outlined above and a statistical model .i and k different attributes with different levels. Then, by expanding Equation (1), we find:Assuming a linear additive form for the multidimensional deterministic attribute vector   as folloTo improve the fitness of the model, violation of irrelevant alternatives need to be avoided using different techniques. In this study, we analyzed the socioeconomic alternatives using a multinomial logit model including socioeconomic attributes with minimum bias and more accuracy by employing the STATA14 program.In this model, coefficients estimated can be used for estimating the rate at which respondents are willing to choose one attribute for another. The trade-off estimated is known as the marginal willingness to pay or part-worth or an implicit price. This expresses the amounts of money respondents are willing to pay to receive more of the non-marketed environmental attribute .(6)Margi, and To analyze welfare, the willingness to pay ttribute .(7)WTPiEucalyptus expansion with their attributes were determined in consultation with respondents in the study area. The identification of an appropriate experimental design is the most important precondition for undertaking a CE analysis. Using the right experimental design, it is possible to create choice sets in the most efficient way that combines attribute levels to alternatives and alternatives to the choice sets [Identification of attributes and their levels is the first and essential step in designing a questionnaire for a choice experiment. In this paper, management scenarios for restricting ice sets . Before Eucalyptus over crop lands would create positive environmental impacts, which were used as attributes of the choice experiment. Complete factorial designs allow the estimation of the full effects of the attributes upon choices that include the effects of each of the individual attributes presented (main effects) and the extent to which behavior relates to variations in the combination of different attributes offered (interactions). As these designs often give an impractically large number of combinations to be evaluated, we reduced the number of scenarios of combinations to an optimum manageable size of nine different choice sets using orthogonality analysis using SPSS software  [Our assumption was that conservation plans that restrict the expansion of NY, USA) . To make3 combinations for a total of 81 alternatives with main effects, which generated nine orthogonal combinations, which were blocked into three different questionnaire versions, each including three choice sets [With the three attributes, each with three labels, we applied an experimental design technique of 3ice sets .The sample design strategy entails four distinct steps: selecting the target (sample) population, determining who to sample (the sample frame), determining the appropriate sample size, and choosing the method of respondent selection and elicitation of response technique. Relevant stakeholders were identified through a brainstorming session with respondents with the help of local experts following stakeholder analysis .Eucalyptus expansion and its impact on biodiversity together with elicitation of response techniques [We considered a final sample of 388 respondents for the final data collection. Then, before administering the choice modeling questions on the respondents, we induced informative discussion about the current situation of chniques ,52.Eucalyptus plantation over crop lands and biodiversity conservation strategies in the study area , accounting for about 46% of their total annual income. Similarly, the average annual income obtained from cultivation of food crops was USD 502.98. Income from non-farm activities (off-farm and remittance) and livestock rearing were found to be UDSD 330.07 and USD 211.43, respectively.All farm households involved in this study possessed varying sizes of plots. The average land holding of respondent households was 1.37 ha, which was utilized for the cultivation of food crops, 2 = 0.0000) criteria implying that the predictor attributes under consideration had strong determination and explanatory power. In Models 2 and 3, we introduced socioeconomic variables to the indirect utility function and observed that presence variable as additive forms and interaction with selected variables respectively.A multinomial logit model was used to analyze the preferences of respondents and their WTP for the ecological improvement schemes . The modp < 0.01) different from zero. The signs of attribute variables were found as expected. Accordingly, the land use plan, to use a small portion of their plots for plantation increased the probability that an option would be chosen by 42%. Similarly, all the rest of the attribute variables increased the probability. Most of the predicted variables significantly (p < 0.01) and positively influenced the preferences of residents for each improvement scheme. In Model 1, the highest (48.95%) probability increase in choice of options was brought by the program for increasing the number of other tree species to be planted.The first model presented in p < 0.001) different from zero. Variables including sex , land size and the number of oxen owned were found to influence respondent choice negatively, showing that a unit increase in the respective variables causes a decrease in the probability of households’ preferences for the improvement program. For this model, the highest (about 49%) increase in the probability that an improvement option would be chosen was observed for the number of other tree species grown. For the non-attribute variables, the number of family laborers had a positive and significant (p < 0.01) effect on respondents’ preferences for improved ecological wellbeing. Results in this model also showed that households with higher income, older in age and with higher number of family laborers had an increased option choice.In Model 2, all the attribute variables and three of the non-attribute variables were found to be significantly (p < 0.001 and p < 0.05) influence respondents’ choice for the improvement program. Among the attribute variables, the number of other tree species to be planted increased respondents’ choice by 50.13%. The interaction of variables that were significant in Model 2 with attribute variables also showed significant influence on respondents’ preferences except for the interactions of income *land fertility, age *number of other tree species to be grown and family labor *number of other tree species to be grown.Results of Model 3 presented how socioeconomic variables that were significant in Model 2 affected option choice in interactions. In this model, attribute variables were found to significantly , planting Eucalyptus on fertile plots to planting on marginal lands, and a change from planting small numbers of other tree species to more diverse tree species for ecological conservation in the study area.We calculated the implicit value of marginal attribute changes by observing the marginal rate of substitution between the price attribute and the respective attribute, i.e., by taking the ratio of the attribute under consideration to the payment coefficient. The marginal willingness to pay (MWTP) measure the amount of money respondents are willing to pay to trade off for a unit improvement in an environmental attribute, or the amount they are willing to pay to prevent the expected welfare losses. For the improvement of the ecological scheme in the study area, the MWTP values represent a change in size of land allocated for Accordingly, the results showed that residents were willing to trade off a USD 54.83 increase in household annual utility cost for the contribution of the land use plan attribute for the ecological improvement programs.Eucalyptus on 75% of their plots to 25% was USD 54.83/person/year. Similarly, to change the households’ need for planting Eucalyptus on fertile plots to planting on more marginal ones, the corresponding compensation variation was USD 24.35/person/year. The compensation variation for enhancing the number of other tree species to be grown, which is the highest value of all, was USD 125.82/person/year.As seen in This study estimated the amount residents of the study area can willingly pay for a policy relevant to ecological improvement schemes. Overall, residents were WTP USD 205.00/person/year on average as a yearly utility fee in support of the ecological improvement schemes in the study area. The WTP estimates for the ecological improvement programs suggest that residents of the study area were diverse in terms of their views regarding ecological wellbeing.Eucalyptus hotspots of the highlands of northwestern Ethiopia is influenced by intensive human activities, land cover changes, and subsequent climate change and loss of biodiversity. This situation will get worse and may result in ecological deterioration unless certain improvements and conservation schemes are not enforced. Recently, rapid land cover changes have been observed in the study area, where Eucalyptus was alarmingly replacing arable land in monoculture plantations, which has impacted the ecosystem and brought transformation of the cultural landscapes in the area.The ecosystem in the Eucalyptus can result in disturbance of the natural ecosystem and loss of ecosystem services [Though the majority of the land in the study area is primarily used for the cultivation of food crops, livestock rearing and plantations, it also provides services including biofuel, fiber, opportunities to store carbon, biodiversity, and recreational and aesthetic values ,54. Neveservices . This inservices .Eucalyptus is grown is expanding rapidly. Studies by Rejmanek and Richardson [Eucalyptus has reached an estimated coverage of about 2.3 million hectares globally since its introduction from its center of origin. In Portugal, for instance, where the species seems to find particularly favorable conditions for successful reproduction, an estimated area of 845,000 ha, which accounts about 26% of the Portuguese forest, is covered with Eucalyptus plantations [Eucalyptus has proven to be particularly successful in tropical and sub-tropical regions like Portugal and Spain, more than elsewhere [Eucalyptus grows well and is well-adapted to conditions in Africa, including Ethiopia.In the study area, the area in which chardson  showed tntations . Despitelsewhere . BecauseEucalyptus can also apparently alter the ecological make-up of the area by changing the scene and population dynamics of flora and fauna. As a non-native species, the expansion of Eucalyptus can result in the transformation of the landscape and a change in the natural ecosystem. This finding is also in line with Toledo et al. [Eucalyptus, which could impact ecosystem properties and functionsThe replacement of crop lands by o et al. , who assEucalyptus and improve the disturbed natural ecosystem in the study area, endorsing ecological improvement schemes towards sustainability of the ecosystem and biodiversity would be essential. Residents of the study area are aware of that Eucalyptus, as a non-native tree species, has a potentially invasive behavior. This conclusion is in line with the study by Vance et al. [Eucalyptus plantations have caused various problems including reduced species diversity and loss of soil nutrients, which threaten ecological security regionally and worldwide [To limit the expansion of e et al. , which sorldwide ,63. In aEucalyptus hotspot highlands of northwestern Ethiopia had diverse preferences to ecological improvement and WTP for the same programs. Multinomial logit results indicated that all attribute variables significantly and positively influenced residents’ willingness to pay for the improvement programs. This conclusion is in line with the studies by [Results presented in this study showed that residents of the udies by ,65,66 thChanges in personal attitudes of residents towards accepting proposed ecological improvement schemes are quite important for sustainable biodiversity conservation. Residents considered in this study differed in terms of demographic variables  and socioeconomic variables . The changes in residents’ preferences for the ecological improvement programs were attributed to these variations. However, there was limited information regarding residents’ preferences and their WTP for the acceptance of ecological improvement schemes focused towards improving the ecological and biodiversity wellbeing.Eucalyptus.Results of separate model runs showed different effects of attribute and non-attribute variables. The significance of all attribute variables in the first and second run showed that the explanatory powers of the attributes were as expected. Among the socioeconomic variables that were included in the second model, income source, age, and number of family laborers were found to significantly influence residents’ choice. The findings also suggest that residents who better made choices of improved ecological conservation were those who had more income sources, were older in age and had more family laborers. This finding is consistent with the study by  who repoEucalyptus plantations, excluding for Eucalyptus plantations, and increasing the number of other tree species to be grown.For all the improvement schemes, residents showed varying levels of preferences. The schemes were designed for improving the level of ecological security and were comprised of three attributes and their levels including reduction of total area of Eucalyptus on less fertile lands for the improvement program (second attribute). Accordingly, there was a 26.75% change in MWTP of respondents for the first attribute . The highest attribute change (61.38%) was observed for the third attribute . The findings are in line with a study by Kim et al. [We estimated the MWTP of respondents by taking the implicit value of marginal attribute changes with respect to the payment coefficient . It measm et al.  which asEucalyptus was estimated to be USD 54.83/person/year. Similarly, the benefits from the exclusion of fertile plots from plantations and increasing the number of other tree species were USD 24.35/person/year and USD 125.82/person/year, respectively; the overall value being USD 205. Differences in attribute values have also been reported by [We found that the contribution of a reduction of plantation area of orted by .Eucalyptus was significantly reduced, fertile lands were set aside from Eucalyptus plantation and the number of other tree species was increased.We found that respondents’ preference for the ecological improvement programs can be improved if land allocated for Our study showed that the socioeconomic backgrounds of the respondents contributed to the heterogeneity in residents’ preferences and their WTP for ecological improvement schemes. This outcome is in line with the study by . Our finEucalyptus plantation. Our findings can be utilized for instructing residents and the provision of information regarding conservation plans for ecosystems and biodiversity.This study is a first attempt to evaluate the economic value of restricting areas of monoculture Nonetheless, we acknowledge the uncertainties with our approach. For instance, our study participants were confronted with a hypothetical bias in which there was no real transactions and thus there might be over estimations.Eucalyptus in the Eucalyptus hotspot highlands of northwestern Ethiopia from the perspective of ecological economics using a CE method and devised attributes that are important for ecological improvement and biodiversity conservation. The study indicated that policy-targeting management advice is essential for the development of a sustainable ecosystem, especially in areas that are fragile in terms of hosting biotic and abiotic components that are essential to healthy functioning of the ecosystem. The findings of this study revealed that the expansion of areas of monoculture Eucalyptus plantation is a big threat for ecological wellbeing and biodiversity in the area. A study by Foresmaire [Eucalyptus in Portugal and part of Spain.This study presents economic estimation of restricting the area of plantations of resmaire  outlinedIn this study, a choice experiment approach was validated for constructing a random utility model and examining the preferences of residents to possible ecological improvement options. The proposed attribute and non-attribute variables were identified by considering previous works including those by Kragt and Bennett,  and LuisEucalyptus hotspot highlands of northwestern Ethiopia is highly disturbed due to the undergoing dramatic land use changes due to human activity. The study is in line with the finding of Townhill et al. [Eucalyptus plantations and ecological deterioration. Validation of the CE approach showed that respondents are willing to pay for the proposed ecological improvement programs.The ecosystem of the l et al.  who repoWe believe that this study yields important findings that can provide trustworthy information to policymakers and researchers and creates public awareness regarding ecological wellbeing and biodiversity conservation. Our findings can address similar areas that demand immediate policy interventions regarding management of development strategies for a given ecosystem and biodiversity.Eucalyptus hotspot areas of the highlands of northwestern Ethiopia. (1) Policies should restrict areas of further plantations of Eucalyptus. (2) Emphasis should be given to land types for the plantation of Eucalyptus setting aside cultivable lands. (3) Focusing on increasing plantation areas of other tree species. (4) Creating awareness on residents regarding the conservation of the ecosystem through restricted plantation areas of Eucalyptus and increasing plantation areas of other tree species. Finally, it is suggested that further research shall be carried out as extension of this study.The findings can provide important implications about relevant attributes for ecological improvement. Based on our findings, the following key policy suggestions are forwarded for the ecologically sensitive