Vegetation Dynamics and Their Response to the Urbanization of the Beijing–Tianjin–Hebei Region, China

Abstract

Rapid global urbanization has caused substantial changes in land cover and vegetation growth. Rapid urban growth in a short time has escalated the conflicts between economic development and ecological conservation, particularly in some metropolitan regions. However, the effects of rapid urbanization on vegetation have not been fully captured, especially accounting for the latest ecological development initiatives. In this study, we chose a typical urban agglomeration, the Beijing–Tianjin–Hebei (BTH) urban agglomeration in China, and analyzed the vegetation variation and the impacts of urbanization on the vegetation growth based on transferable methods, using data such as the Normalized Difference Vegetation Index (NDVI) and the nighttime light (NTL). The results indicate significantly enhanced vegetation growth in the BTH region, with a strikingly spatial pattern of greening in the northwest, and browning in the southeast from 2001 to 2018. Besides this, the results enclose most of the areas (72%) of built-up land in the BTH, which tended to brown in the process of rapid urban development, while 27% greened with increasing urbanization. This means that the vegetation’s response to urbanization shows apparent differences and geographic heterogeneity along the urbanization gradient at the urban agglomeration scale. Parts of the periphery of the metropolis and the central areas of developing cities may experience a browning trend; however, the core urban areas of urbanized metropolises demonstrate greening, rather than browning. Furthermore, this study provides solid evidence on the remarkable greening impacts of several ecological restoration projects which are currently underway, especially in ecologically fragile areas (e.g., the suburbs). The implications derived from the urban ecological development and the transferable methodology deployed in this paper facilitate the unfolding relationships between urbanization and social-ecological development. Our findings provide new insights into the interactions between vegetation dynamics and urbanization at the regional level.

The Spatio-Temporal Variation of Vegetation and Its Driving Factors during the Recent 20 Years in Beijing

“…This phenomenon can also be observed in developed countries such as Japan, the United Kingdom, and America [73]. The greening work in the area is getting better and better in the regions, which benefited from the urban park construction policy that Beijing has long persisted in [35,74]. In a word, proactive human activities play an important role in vegetation restoration [24,75].…”

“…Jiang M et al [34] calculated the fractional vegetation coverage by the method of dimidiate pixel model based on NDVI, which suggests that human activities are very significant factors to influence and explain the changes in Beijing and they are highly spatially heterogeneous from 2000 to 2015. Chang Y et al [35] considered that the response of vegetation to urbanization showed obvious differences and geographical heterogeneity in the urbanization gradient based on the nighttime light data. Nevertheless, these works do not continue into the latest year and quantify the role of human activities and climate factors in the process of vegetation restoration and degradation in Beijing.…”

Exploration of Influencing Factors of Land Surface Temperature in Cities Within the Beijing–Tianjin–Hebei Region Based on Local Climate Zone Scheme

“…The BTH region is characterized by the typical Monsoon Climate of Medium Latitudes, characterized by hot, rainy summers and cold, dry winters [54]. Cities within this region exhibit similar annual average humidity and precipitation (Table 1).…”

“…Despite the socio-economic advantages brought by this swift urban growth, there is a growing concern about the adverse effects on the urban thermal environment, which poses health risks to the region's populous and affects the local ecosystem [56], [57]. Under the background of Coordinated Development of the BTH Region, the scale of urbanization in this region is expected to continue expanding [54], and this region is facing the risk of further deterioration in thermal environment conditions. Additionally, the BTH Region also faces an obvious imbalance in urban development, leading to varying degrees of urban heat environmental degradation across cities [58].…”

Spatiotemporal patterns and drivers of summer heat island in Beijing-Tianjin-Hebei Urban Agglomeration, China

“…Most of the southern plains are cultivated land and artificial urban vegetation. From the perspective of interannual changes, Chang et al [55] found a significantly enhanced vegetation growth in BTH region, with a strikingly spatial pattern of greening in the northwest and browning in the southeast from 2001 to 2018. Thus, the background vegetation status of the BTH urban agglomeration and the vegetation trends from 2001 to 2018 may be two main factors affecting the spatial heterogeneity of summer SUHI, which has also been verified in Gui et al [27].…”