Paper Reviewed:
Uy, P. D., & Nakagoshi, N. (2008). Application of land suitability analysis and landscape ecology to urban greenspace planning in Hanoi, Vietnam. Urban Forestry and Urban Greening, 7(1), 25-40. doi: 10.1016/j.ufug.2007.09.002
I chose to review this paper due to my keen interests in cities and urban environments. I was naturally drawn to the subject of this paper as I wanted to learn more about the application of landscape metrics and principles in planning the ‘living space’. The authors of this paper examined the following: How to apply LSA modeling, the ecological factor threshold method, and landscape-ecology principles in planning comprehensive green structure through examination of Hanoi, Vietnam and of the 2020 Hanoi Master Plan.
Urban green spaces are an important component of urban ecosystems. Green spaces provide numerous social and environmental services that contribute to the quality of life in cities, as well as play a pivotal role in preserving biodiversity in urban areas (Uy & Nakagoshi, 2008). For example, they sequester CO2; produce O2; regulate microclimates; reduce the heat island effect in cities; and offer recreational and social values. Therefore, optimizing the benefits of urban green spaces is one of the key tasks of urban planners to unravel, especially with forecasted urban population increase and expected higher urban densities.
In their paper, Uy and Nakagoshi (2008) define urban green spaces as outdoor places with significant amounts of vegetation, which exist mainly as semi-natural areas, or as last remnants of nature in urban areas. However, functions of green spaces vary depending on factors such as the size, shape, diversity, history, and distribution within a city, in addition to the city design and management. Consequently, identifying suitable sites for conserving and developing green spaces is a critical step in ensuring their roles and functions. More importantly, if urban green spaces are organized by combining a variety of multi-purpose green spaces, called a green network or urban green structure, their roles and functions can be enhanced. So, land suitability analysis (LSA) using GIS to gain site information, the ecological factor threshold method to quantify green area necessary to maintain an ecological balance, and landscape-ecology principles to organize green spaces in urban areas are identified techniques that could be used for effective development of urban green spaces by Uy and Nakagoshi (2008). Accordingly, the purpose of their study is to answer: How to apply LSA modeling, the ecological factor threshold method, and landscape-ecology principles in planning comprehensive green structure through examination of Hanoi, Vietnam and of the 2020 Hanoi Master Plan.
Hanoi, the capital of the Socialist Republic of Vietnam, is an ancient city with nine urban districts and five rural districts. The city is the political, economic, cultural, and technological center of the whole country. At present, the city resembles a hybrid of the basic forms (centralized, linear, and gridiron), which express cultural and physical influences over time (Uy & Nakagoshi, 2008). The 2020 Hanoi Master Plan proposes to plan and develop the city following a centralized form, with the city center marked by the ancient quarter, to address population increase in conjunction with the population carrying capacity of the city. This includes, but not limited to, consideration for the carbon-oxygen balance calculated on the CO2 consumption of trees, green structure planning, and allocation of per capita green area. Uy and Nakagoshi (2008) narrow the study boundaries to the downtown area of Hanoi city to conduct the LSA and the ecological factor threshold method, with application of landscape-ecology principles.
The LSA for building a green space map was carried out based on existing land-use maps, air pollution maps, water body system maps, maps of valuable historical and cultural landscapes, and the Vietnamese standards for planning and designing urban and industrial areas. Next, the following were conducted through the spatial analysis functions of ArcGIS: identification and collection of spatial data, determination of suit- ability scores for each factor (e.g. existing land-use and air quality), weighting with the analytical hierarchy process (AHP) and pairwise comparisons, data integration and analysis, and output evaluation. The suit- ability scores for each factor ranged from 1 to 3, where a higher score indicated an area more suitable for developing green spaces. Following these steps, a suitable green space composite map was then created to compare with the 2020 Hanoi Master Plan. When compared, they were found to be compatible – i.e., all the planned sites for green spaces were found to be suitable.
The ecological factor threshold method was implemented based on the principles of ecological balance in order to quantify how much green area was needed for Hanoi. This was analyzed on the key ecological elements including: the population carrying capacity, carbon-oxygen balance, and the supply-demand equilibrium of water resources. Unfortunately, the planned per capita green area of 18m2 in the 2020 Hanoi Master Plan was found to be insufficient considering the expected population growth, particularly in urban population, along with the population carrying capacity of the city. Instead, 1321 trees per ha (for 354.52 ha) was needed to avoid a serious disparity in the carbon-oxygen balance.
Landscape-ecology principles were implemented through concepts applicable to land use planning and landscape architecture through the following metrics: patch size, number, location; edge parameters; corridors and connectivity; and network mosaics. These metrics were integrated in their study to help address the spatial dimensions of sustainable planning, as well as assess whether the planned green spaces can resist (future) uncontrolled urban development. From this, the creation of a greenbelt for natural and ecological preservation was supported while recommendations were made to limit or prohibit development activities within and near green wedges.
Overall, the researchers concluded that they were able to reduce subjectiveness in their analysis by integrating the AHP and pairwise comparison process when applying LSA, as well as having introduced a useful, effective and efficient method for identifying suitable sites for developing urban green spaces through the ecological factor threshold method. Moreover, through the application of landscape-ecology principles, they were able to elaborate on the discussion of results with respect to green structure at the city scale and neighbourhood scale. While this subsequently achieves the set purpose of their study, I lack confidence in their findings due to uncertainty of data source (i.e., unspecified) and lack of explanation to justify why the weighting score for each factor did not total to 1.0 when combined. As a result, I would rate this paper 6 out of 10 considering the capacity for improvement.