Annual Conversion of Green-Space Expansion into Socioeconomic and Ecological Benefit in Xi’an, China

Abstract

Green space statistics in the annual unit may overestimate the effectiveness of planning efforts if the two are not correlated in their movement. This study applies the ERC analysis to Xi’an, China, based on the 2009–2019 series of annual statistics on per capita green space area, built-up land, socioeconomic benefit, ecological benefit, overall benefit, and four ecological processes, namely cooling, humidification, oxygen release, and carbon fixation. Each increase/decrease in green space area is matched with changes in socioeconomic and ecological performance, in a way that the annual information is transformed to ten successive intervals. Based on this transformation, this analysis computes conversion yield, productive conversion, expansion lag, contraction stress, recovery without expansion, and ecological coordination as the minimum of four ecological process scores. Xi’an had five productive conversion intervals, three expansion lag intervals, one contraction stress interval, and one recovery interval without any scale increase. The best interval was 2016–2017: the increment in per capita green space area was 1.70 m² person⁻¹, and that of socioeconomic, ecological, and overall benefit was 0.21, 0.18, and 0.20, respectively, leading to a highest conversion yield of 0.118 score units for each m² person⁻¹ of new green space area. The intervals of 2011–2012, 2012–2013, and 2015–2016 indicated that additional green space area does not correlate well with benefit response. In particular, ecological coordination was best in 2017, in which four ecological process scores were at or above 0.69, while the 2015 combination of good ecological score and low humidification floor (0.03) revealed ecological imbalance. It appears that annual green space performance in Xi’an relied heavily on conversion yield and ecological process balance rather than on per capita green space area. The target of 28.5–29.0 m² person⁻¹ can be justifiable if coupled with monitoring of conversion yield and minimum ecological process score.