Differentiation of Vegetation Community Characteristics by Altitude within Urban Parks and Their Service Functions in a Semi-Arid Mountain Valley: A Case Study of Lanzhou City

Abstract

As the primary component of urban green space, parks play an important role in improving local environments and quality of life for city inhabitants. To date, much research on urban park plant community characteristics has been conducted worldwide, but studies focusing on differences across altitudes have been rare. Here, we have investigated fractional vegetation cover (FVC), plant species diversity, plant species composition, and plant life-form types along altitude gradients within four urban parks (Jincheng, Renshoushan, Baitashan, and Lanshan) in Lanzhou city (China) by field sampling and remote sensing. Spatial variations in plant community characteristics at different elevations, as well as their ecological, social, and integrated service levels, were analyzed using combined methods of remote sensing interpretation, mathematical statistics, and service function assessment. The results showed that: (1) spatial variations in plant communities along elevation gradients exhibited a distinct regional differentiation between parks; (2) Lanshan Park had the lowest FVC (43.6%) and plant species diversity (59 species), and these two parameters exhibited the most dramatic spatial change as elevation increased; the opposite phenomenon occurred in Renshoushan Park (FVC of 56.6%; 81 species); (3) the differences in the natural service level of the plant community were smaller for the social and integrated service levels. The highest natural service level occurred in Renshoushan Park, while Jincheng Park had the highest social and integrated service levels; the smallest values occurred in Lanshan Park. We conclude that scientific park management is urgently required to ensure the safety and sustainable development of the local urban ecosystems and to improve the ecological and social service levels of the individual urban parks, especially Lanshan Park. These findings also provide key insights to improve urban park communities and service levels in similar mountainous, semi-arid zones.