*3.1. Description of the Study Area*

The National Park of Eastern Macedonia and Thrace (NPEMT) covers approximately 73,000 ha and includes the wetlands of Delta Nestos and Lakes Vistonida and Ismarida (Figure 4). Within the NPEMT, habitats of significant biodiversity and ecological value are in coexistence with extensive human activities (urban, rural, tourist, industrial). The NPEMT extends to the administrative boundaries of six (6) municipalities, has 43 villages, 10,500 households, and an approximate population of 29,000 people.

**Figure 4.** The geographical boundaries of the National Park of Eastern Macedonia and Thrace (NPEMT).

The main characteristics of the NPEMT area are summarized below:


#### *3.2. Implementation of the Methodological Framework*

The available land uses and subareas of the NPEMT were measured using the software Mapinfo Professional 12.0 and data from the European program for land cover CORINE (Coordination of Information on the Environment) 2000 [39] (see Table 1). The Biocapacity of the NPEMT was therefore estimated at 192,283 hectares of biologically productive land (area in Gha).


**Table 1.** The calculations of the Biocapacity of the NPEMT.

\* Source: [35].

The results from the estimation of Ecological Footprint for the reference year (2013) are presented in Table 2. Relative estimations took place for the Ecological Footprint calculation, deriving by the real resident population of the NPEMT, which was estimated at 143,628 Gha.

The existing equivalent resident population of the NPEMT was calculated using Equation (3) to 36,960 equivalent residents.

$$P\_{\text{eq}} = \frac{P\_1}{EF\_1} EF = \frac{29,276}{143,628} 181,324 = 36,960 \text{ equivalent residuals}$$


**Table 2.** The calculation of the Ecological Footprint in the totality of the NPEMT.


**Table 2.** *Cont.*

\* Built-up areas were estimated for the totality of the NPEMT and not separately for every activity due to lack of available data.

The Carrying Capacity of the NPEMT was calculated using Equation (2) to 39,193 equivalent residents.

$$\text{CC} = \frac{\text{B}c}{\frac{\text{EF}}{\text{Peq}}} = \frac{192,283}{\frac{181,324}{36,960}} = 39,193 \text{ equivalent residuals}$$

#### *3.3. Results and Discussion*

The Ecological Footprint of the NPEMT was estimated at 181,324 Gha or 4.9 Gha/perseq, slightly higher than the European mean (4.69 Gha/perseq) [36], whereas the Biocapacity of the NPEMT was estimated at 192,283 Gha. The Carrying Capacity of the NPEMT was estimated at 39,193 equivalent residents; a number higher than the existing equivalent residents (36,960 equivalent residents). Therefore, the area is able to meet the needs of its population provided that the consumption patterns will be stable or more efficient. Also, there is a considerable margin for the development of new activities within the NPEMT boundaries. More specifically, regarding the tourism activity, although it is a common problem in protected areas worldwide, the NPEMT has a Carrying Capacity surplus of approximately 2000 equivalent residents, indicating that it can support a certain number of extra tourists annually.

The major contributors on the total Ecological Footprint of the NPEMT were the annual consumptions of products and energy related with households (79%) and the annual consumption of energy related with private transportation (10%), as shown in Table 3.

Analyzing the Ecological Footprint of the NPEMT into its land uses as it is presented in Figure 5, it can be observed that the main contributors are "1. Agricultural products" (36%), "2. Livestock products" (30%), and "5. CO2 Emissions" (30%). It is remarkable that the consumption needs of products and energy correspond to approximately 68% and 30%, respectively, of total Ecological Footprint. Among the products, beef annual consumption (22.8%) was identified as the key factor contributing to the Ecological Footprint of the spatial entity under study, while fruits and vegetables (15.2%) and beverages (14.3%) followed. The above results are in agreement with the literature [40], which indicates food consumption as a key contributor to the Ecological Footprint in areas where human activities exist. Potential changes in the nutritional habits of residents and tourists, such as partial replacing of beef, could significantly reduce the total Ecological Footprint.


**Table 3.** The contribution of several human activities on the total Ecological Footprint of the NPEMT.

The fact that the proposed framework has been applied effectively to the NPEMT is encouraging in relation to its applicability. Also, the development of the algorithm that calculates the Ecological Footprint, the Biocapacity, and the Carrying Capacity of the protected area under study by introducing 48 inputs has reduced the complexity and the expertise needed for the implementation of the proposed framework. The evaluation of the environmental sustainability of the protected area under study has been elaborated in a holistic approach taking into account anthropogenic activities. Moreover, the results of the framework can provide clear information about the progress towards sustainability and the ability to incorporate new activities within the environmental boundaries of the protected area under study.

On the other hand, the authors recognize a certain degree of subjectivity in the evaluation process which is related to the application of certain assumptions required due to the lack of data. All assumptions are supported by statistical data, surveys, literature references [41,42], etc. Moreover, there was no provision for the implementation of an uncertainty and sensitivity analysis method in order to identify and cope with the uncertainties raised by the integration of the LCA method in the proposed framework.

**Figure 5.** The Ecological Footprint results of the NPEMT.

#### **4. Conclusions**

The current work introduced a methodological framework that is able to evaluate the Environmental Sustainability of a spatial entity with anthropogenic activities and applied it to the National Park of Eastern Macedonia and Thrace. The key advantage of the proposed framework is that it can assess entities that present various human activities, such as households, tertiary sector, tourism, and transportation. In order to achieve this, the proposed methodological framework equates the meaning of Environmental Sustainability to Carrying Capacity, estimating the maximum equivalent population of residents which can live sustainably within a spatial entity. For this estimation, the following are considered: (a) the available biologically productive land (Biocapacity) of the spatial entity, (b) the land needed to satisfy the consumption needs of the anthropogenic activities in products and energy (Ecological Footprint) within the spatial entity, and (c) the real value of the equivalent residents, since all the consumption needs of the anthropogenic activities are not directly connected to the population size. For example, the energy consumption of buildings depends on their surface and use and not on the number of residents. The value of Carrying Capacity comes from the division of Biocapacity to Ecological Footprint per equivalent capita (EF/Peq).

The implementation of the proposed framework contributes to the improvement of the functionality and applicability of the existing methods for evaluating the environmental sustainability of protected areas, while providing clear information about the progress toward sustainability and the ability to incorporate a new activity within the boundaries of the protected area under study. However, particular points, related to the assumptions and the uncertainties, have been identified that need to be improved in order to strengthen the objectivity of the evaluation process and to treat the uncertainties due to the integration of the LCA approach.

Especially, the results from the application of the proposed framework in the NPEMT indicated a positive environmental performance of the region, since the Carrying Capacity is calculated at 39,193 equivalent residents, when the existing equivalent population was estimated at 36,960 equivalent residents. Therefore, the area is able to meet the needs of its equivalent population provided that the consumption patterns will be stable or improved. The results encourage a sensible expansion of touristic activities. Household activities are the main contributor (79%) to the total Ecological Footprint, whereas product consumption is responsible for 68% of the total Ecological Footprint, which is in agreement with other studies.

The authors are planning to continuously improve the effectiveness of the proposed framework by developing supporting software that will enable its fast and reliable implementation and by applying an uncertainty analysis for different scenarios in order to strengthen the reliability and credibility of the integration of the LCA approach in the proposed framework. Another key issue that needs to be examined in the future is the potential assistance of an experts group in order to determine the values of the assumptions needed in a more objective process.

The management bodies of protected areas have to advise the Public Administration on the sustainability of new projects to be carried out within their boundaries and to develop sustainable strategies ensuring the harmonious coexistence of natural capital with proposed anthropogenic activities. Therefore, both the management bodies of the protected areas and the accountable administrative authorities need to assess and quantify the impact of existing and future human activities that can be developed to satisfy current and future needs, while in parallel sustaining the environmental and ecological health. The proposed Environmental Sustainability Assessment framework can serve as a tool to support decision-making through Carrying Capacity estimation and monitoring.

**Author Contributions:** All authors contributed equally to the text. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors would like to thank the NPEMT Management Body for supporting the case study implementation.

**Conflicts of Interest:** The authors declare no conflict of interest.


**Table A1.** The Ecological Footprint indicators.

**Appendix A**


**Table A1.** *Cont.*



(commercial ship)



1All the product's consumptions (agricultural, livestock and fishery, and aquaculture products) were calculated similarly to the calculation of "bread consumption," replacing the average consumption of each product in g per kg of human mass per day.2 The annual thermal energy consumption was calculated similarly to the annual electricity consumption.
