## 2 Growing Population, Land Consumption, and Densification
### Densification in High-Density Cities in China: The Direction already Taken  
Actions for densification have already been taken in China: in 2003, the \"prohibition of land supply for villas\" was issued to stop low-dense developments by the Ministry of Land and Natural Resources. The rule had to be repeated five times because it was not fully implemented. In 2019, the Ministry of Housing and Construction issued an urgent notice requesting the suspension of the approval of projects proposing vills. Subsequently, the limit to the minimum FAR was extended to all low-density typologies such as villas, double-family row houses less than four stories, and townhouses. The \"prohibition of villas\" is justified by China's arable land sharply decreasing [72]. The National Land Planning Outline required in 2006 that by 2020 the amount of cultivated land would be maintained at 1.865 billion mu, a goal implemented by the \"red line of cultivated land\" and the construction land quotas mentioned in paragraph 1.2. The goal was achieved, and the same amount of 1.8 billion mu is set for the future [73]. Beyond the prohibition of low-density developments and the red line, densification processes are happening: two very relevant cases are Shenzhen and Shanghai. Shenzhen is running out of land supply for development: only 2.23% of the 195,284 hectares of the city is still available for growth, and real estate prices have skyrocketed. Therefore, Shenzhen is demolishing and densifying some already high-density residential areas. This phenomenon interests mostly the \"villages in the city\", where in the 1980s, after opening up, the original 1-story buildings were extruded to several stories and almost to the whole lot, forming in several stages a hyper-compact urban fabric [74; 75]. An example of this process is Dachong village (Table 2). The area used to house 931 families in 1400 buildings on 69 ha (13.5 families per ha), but in 2011 the whole village was demolished, the building type changed, and the density increased from 1.1 million sqm to 2.8 million sqm and 7382 residential units (107 units per ha). The transformation also increased the land uses, shifting from residential to mixed-use conditions. These actions of densification can be controversial because they often start gentrification [76; 77]. In Shanghai, the FAR of low-rise and high-density houses has generally increased. In recent years densification has happened mostly along the metro lines and central streets, for example, in Hengshan Street, where towers have substituted the original low-rise urban tissue [78]. Moreover, resettlement communities are impacted by densification. High rises fill empty lots, such as the \"Vertical courtyards apartments\" in Hangzhou by [PERSON] [79] and \"The third space\" in Tangshan by [PERSON] or entire parts are demolished and \begin{table}
\begin{tabular}{c c c c} \hline \hline
**District** & **2021 (Million)** & **Area (km2)** & **Pop Density** \\ \hline Metropolitan Area & 12.748 & 8657.32 & 1472.5 \\ Suzhou City & 6.7148 & 2899.38 & 2315.9 \\ Gusu & 0.924 & 83.42 & 11/07.6 \\ Wuzhong & 1.3889 & 745 & 1864.3 \\ Xiangcheng & 0.891 & 489.96 & 1818.5 \\ Suzhou New District & 0.832 & 332.37 & 2503.2 \\ Suzhou Industrial Park & 1.1339 & 278.19 & 4076.0 \\ Wujiang & 1.545 & 970.44 & 1592.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Area and population indicators of each district in Suzhou. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Village Name** & **Site Area** & \begin{tabular}{c} **Total Building** \\ **Area (Before)** \\ \end{tabular} & \begin{tabular}{c} **Total Building** \\ **Area (After)** \\ \end{tabular} & \
\begin{tabular}{c} **FAR (Before)** \\ \end{tabular} &
\begin{tabular}{c} **FAR (After)** \\ \end{tabular} \\ \hline Dachong village & 36.40 ha & 160.52 ha & 280.00 ha & 4.41 & 7.70 \\ Jianyeli Shikumen & 1.79 ha & 2.33 ha & 4.77 ha & 1.30 & 2.51 \\ Tuanjie Village & 2.80 ha & 4.43 ha & 14.11 ha & 1.58 & 5.04 \\ \hline \hline \end{tabular}
\end{table}