# Implementation of the 3-30-300 Green City Concept: Warsaw Case Study
## 2 Materials and Methods
### Case Study  
#### 2.2.1 Test Area  
The methodological assumptions were verified using the example of Warsaw, the capital of Poland. Warsaw is located in the central part of the country (Figure 2a), within the Masovian Voivodeship. It is the largest city in Poland, covering an area of 512 square kilometers, and is divided into 18 districts (Figure 2b). According to demographic analyses from 2023, the city has a population of 1,861,644 people [25]. The most populous district is Mokotow, with 225,916 residents, while the least populous is Rembertow, with 24,670 residents. Warsaw is a complex city in terms of urban structure and diversity of ecosystems. The choice of Warsaw as a research object is justified by several key aspects, including the following:  
* Population Density: As the largest city in Poland, Warsaw has a high population density of 3600 people per square kilometer [26]. This presents a significant challenge for urban planners and designers to ensure an adequate amount of urban greenery for its residents. The intensive development often limits space for green areas, making the analysis of existing green spaces and the planning of new ones crucial for improving the quality of life in the city. * Diversity of Green Areas: The city boasts numerous parks, urban forests, squares, and other forms of greenery that can serve as model examples for studying the accessibility and quality of green spaces. Parks such as Lazienki Krolewskie, Pole Mokotowskie, and Park Skaryszewski are located in the central part of the city, offering an opportunity to assess whether their prime locations contribute to easy access for residents across various districts. Their accessibility plays a crucial role in determining how effectively these green spaces meet the needs of the local population for recreation, relaxation, and exposure to nature. In addition to these central parks, the city also has a variety of green areas spread across more peripheral districts, highlighting a mix of urban forests and smaller green spaces that support local ecosystems and offer residents access to nature closer to their neighborhoods. This variety is essential for providing all city residents with adequate green space, regardless of their proximity to the city center. Figure 3 illustrates the distribution of parks and forests with an area greater than 1 hectare, offering a visual representation of green space coverage and density throughout the city. This map provides insights into how these areas are dispersed, potentially identifying regions with limited green space and guiding urban planning efforts to improve green infrastructure in underserved areas. Figure 2: Location of Warsaw in Poland (**a**) and the division of the city into districts (**b**). * Urban Policy: Warsaw has numerous projects and initiatives related to ecology and sustainable development. One example is a project called \"Million Trees\" [27], which involves planting one million trees in Warsaw. The program involves residents, who can indicate locations for planting using a mobile application called \"Warszawa 19115\" in the \"Plant a tree\" tab. The application has been issued by the Warsaw City Hall (Poland) and is available on Google Play (for Android systems) and the App Store (iOS). The main goal of the program is to plant trees along the city's main streets, in parks, squares, and other accessible places, i.e., where residents expect them to be. Another example of a similar activity is the Zielone Ulice (Green Streets) project [28], which focuses on changing the appearance of the city's main arteries and involves creating new plantings and rebuilding existing greenery arrangements along dozens of streets in Warsaw. The process includes consultations with residents and the creation of concepts that will be implemented in stages over several years. Another example is the program involving the de-concretization of urban space, i.e., the removal of concrete pavements In the city, allowing for the creation of new green areas.