Race and affluence shape spatio-temporal urbanization trends in Greater Houston, 1997 to 2016

Urbanization results in increasing impervious surfaces with the potential to threaten fragile environments and heighten flood risks. In the United States, research on the social processes driving urbanization has tended to focus on the twenty-first century, but less is known about how temporal trends arose from the spatial layout of the urban land upon which this growth was founded. To address this gap, we present a novel interdisciplinary synthesis using neighborhood-level census data in tandem with a satellite-derived annual land cover change time series to assess the role of race, affluence, and socioeconomic status in shaping spatio-temporal urbanization in the Houston metropolitan area from 1997−2016. Results from cross-sectional and temporal regression models indicate that while social dynamics associated with historical versus recent urbanization are related, they are not identical. Thus, while temporal change in Houston's urbanization is driven primarily by socioeconomic status, the social dynamics associated with spatial disparities in urbanization relate primarily to race, regardless of socioeconomic status. These results are noteworthy as urbanization in Houston does not fully comport with existing theoretical perspectives or with empirical findings nationally. Instead, we suggest these findings reflect the city’s politics and culture surrounding land use. Thus, beyond its important social and environmental implications, this study affirms the utility of fusing socio-demographic data with satellite remote sensing of urban growth, and highlights the value of the socioenvironmental succession framework for characterizing urbanization as a recursive process in space and time.     

Planning for social inclusion: The impact of socioeconomic inequities on the informal development of farmland in suburban Beijing

Informal development on farmland is not only a major problem facing thousands of people, but also a major challenge to land use planning. In the rapidly growing literature on informal land development in China, most authors claim that ambiguous property rights and the dual land tenure system are the primary factors involved. As a result, existing state-led land use planning responses to informal development are solely focused on strengthening the legal regulation of land development. This paper challenges this approach, on the basis of the theory of urban informality. By examining many illegal gated communities in suburban Beijing, the paper argues that the informal development of farmland on the urban fringe is the result of local grassroots groups spontaneously responding to socioeconomic inequities in the context of transition to a market economy. These inequities mainly concern distributive inequity, procedural inequity and contextual inequity in relation to land use. It appears that the ongoing market-oriented initiatives of the state government could worsen informal land development unless these socioeconomic inequalities at the local level are tackled. The growing civil society is another change to the state's control of informal land development in China's cities. A new land use planning system which has more concern for social inclusion rather than focusing on centralized control is imperative in China.     

Public policy change and its impact on urban expansion: An evaluation of 265 cities in China

Public policies play a vital role in shaping our cities. However, the impact of public policies on the spatial expansion of urban areas needs to be better understood in order to achieve better policy outcomes. During the period of China’s economic reform, the central government of China has made many changes in three sets of public policies—regional development policies, the household registration (hukou) system, and urban land and housing market policies—to promote coordinated development of small, medium and large cities. This study aims to examine the effects of these public policy changes on urban expansion across 265 Chinese cities at or above prefecture level. We first quantify the spatial patterns of urban areas and evaluate the extent of urban sprawl of the 265 cities from 1995 to 2015 using multi-temporal land cover data. These cities are classified into six categories according to a city tier system used in China. Through a set of individual fixed-effects models, we then explore how changes in the three sets of policies have influenced urban expansion differently across different-tier cities. Results show that sprawling patterns of urban expansion, which have been more prominent in small and medium sized cities since 2000, are associated with shifts in policies to support stronger economic and population growth as well as real estate development. Our findings highlight the need for policymakers to take a holistic approach by considering the size of cities together with their social, environmental, and economic characteristics in order to minimise inequality and achieve coordinated urban development goals.     

Evaluation and simulation of the impact of land use change on ecosystem services trade-offs in ecological restoration areas,China

To restore China’s degraded environment and improve ecological balance, the government launched a land use policy known as the Grain for Green Program (GFGP), which is the largest ecological construction project in China or anywhere else. It has greatly increased the vegetation cover on the Loess Plateau but occupied the space of agricultural development (AD) over the years. Research on the impact of policy implementation on ecosystem services (ESs) and their trade-offs can support scenario analyses that provide realistic guidance for decision makers to formulate future regional ecological restoration planning. Our focus is Ningwu County and Jingle County on the Loess Plateau, a typical ecologically fragile and impoverished area where expansion of vegetation cover has driven extensive loss of farmland and its benefits to farmers.In this study, soil conservation (SC), water yield (WY), habitat quality (HQ), and food supply (FS) were selected to assess the change of ESs and their trade-offs in different scenarios that represent ecological restoration and land reclamation policies. The results revealed that overall ESs had the largest increase but there were more trade-offs among ESs under the GFGP scenario. For a single ESs, SC and HQ were increased while FS and WY were decreased under the GFGP scenario. From the view of trade-offs, the GFGP scenario exhibited more trade-offs than the AD scenario. Furthermore, compared to the GFGP scenario, the numbers of sub-watersheds with trade-offs of ESs decreased under the AD scenario. With more concern about the contradiction between implementing GFGP and protecting farmland, we confirm that it is extremely unwise to incessantly implement GFGP to improve overall ESs without considering the trade-offs among ESs. Given the certain sub-watersheds mainly developing agriculture, the AD scenario appears to best reduce trade-offs among ESs and ensure the improvement of ESs. Therefore, it is of great significance to realize the win-win situation of regional ecological and resource demand to find the most suitable development direction in the future.     

The impact of urban expansion on agricultural land use intensity in China

China's urbanization has resulted in significant changes in both agricultural land and agricultural land use. However, there is limited understanding about the relationship between the two primary changes occurring to China's agricultural land – the urban expansion on agricultural land and agricultural land use intensity. The goal of this paper is to understand this relationship in China using panel econometric methods. Our results show that urban expansion is associated with a decline in agricultural land use intensity. The area of cultivated land per capita, a measurement about land scarcity, is negatively correlated with agricultural land use intensity. We also find that GDP in the industrial sector negatively affects agricultural land use intensity. GDP per capita and agricultural investments both positively contribute to the intensification of agricultural land use. Our results, together with the links between urbanization, agricultural land, and agricultural production imply that agricultural land expansion is highly likely with continued urban expansion and that pressures on the country's natural land resources will remain high in the future.     

Detecting the impact of the “Grain for Green” program on the mean annual vegetation cover in the Shaanxi province, China using SPOT-VGT NDVI data

In order to reduce the soil erosion rate on the Chinese Loess Plateau, the Chinese government launched in 1999 the “Grain for Green” program (GfG). The objective of this program was to increase the forest cover on steep slopes in the landscape by planting trees and sowing grasses on former cropland. The program was a massive investment by the Chinese government. By the end of 2005 the GfG-program was implemented in an area of 87,000 km² in which about 400–600 million trees were planted. At present it is not known to what extent this program was successful. This paper examines the effects of the GfG-program on the mean annual vegetation cover in the Shaanxi province. A decadal time series of SPOT VEGETATION imagery from 1998 till 2005 were used to calculate NDVI-values in four counties with different rainfall regimes. By means of a regression between preceding rainfall and NDVI-values the effects of rainfall variability were filtered out. A trend analysis of the corrected NDVI time series pointed out that the GfG-program resulted in a significant increase of the vegetation cover on farmland in the northern part of Shaanxi province. In the southern part of the province, which has a more humid climate and large areas of irrigation farmland no significant increase of the vegetation cover on farmland could be detected.     

城市LUCC时空格局对地表温度的影响效应研究 ——以广西柳州市为例

研究目的:定量分析中国西南典型重工业城市——柳州市的土地利用、地表温度时空演化特征以及不同土地利用类型对地表温度的联合影响效应。研究方法:利用1991年Landsat 5的TM影像和2013年Landsat 8的OLI/TIRS影像数据,通过遥感技术反演提取研究区归一化植被指数(NDVI)、归一化差异建筑指数(NDBI)、改进的归一化差异水体指数(MNDWI)以及地表温度(LST)等遥感参数,基于遥感指数叠加分类法获取城市土地利用/覆盖(LUCC)信息。研究结果:(1)柳州市22年间LUCC变化剧烈,受人为因素影响强烈的地物类型为建筑用地、耕地和裸地。其中,建筑用地变化幅度最大,面积增加了126.71%,新增建筑用地主要源于城市中原有的耕地类型。(2)两期地表温度数据均显示,城市建筑用地的地表温度最高,水体的地表温度最低,建筑用地升温效果显著,是造成城市热岛效应的主要原因之一。(3)影响因子相关性与多元回归分析揭示,城市中各地物类型面积比与地表温度均具有一定的相关性,但差异性较大。其中,建筑用地、裸地与地表温度呈正相关,林地、水体与地表温度呈负相关。研究结论:城市各种LUCC类型的地表温度差异较大,水体和林地在缓解城市热岛效应方面作用十分显著,两者比较,水体的降温效果要优于林地。     

Developing an appropriate land use methodology to promote spatially just,formal retail areas in developing countries: The case of the City of Cape Town,South Africa

South African scholars have increasingly recognized that the prevailing management system for land use is one not relevant to the current spatial needs of the country's settlements. These include, in particular, the need to create sustainable, spatially just and resilient settlements and to develop land in a manner that promotes efficient urban development. The debate in the South African literature on land use management has, with a few notable exceptions, yet to venture into the specific mechanics of how to fix this system, ways the system can be used to create a spatially just urban form, or its applicability in formal retail areas.This paper addresses these questions within the context of formal retail areas and the zoning category that these are typically found in, namely that of the General Business zone. This paper initially investigates the current exclusionary nature of formal retail areas in the context of South Africa and within Cape Town and how this is linked to the more macro patterns of spatial exclusion within Cape Town. It is argued that within the context of Cape Town there is a need to focus on both commercial, particularly formal retail, as well as residential, areas with regard to the project of creating a more spatially just city. It is subsequently demonstrated, firstly, how zoning scheme provisions could be used as a mechanism to address these patterns of exclusion in formal retail areas, specifically exploring provisions that would encourage inclusion of informal and microenterprises within shopping malls. Secondly, it is demonstrated how provisions can be included that create a safer and more inviting environment for public transport users and poorer employees and consumers, in formal retail areas.The contribution of this paper is to initiate a long overdue conversation regarding the relationship between land use management and social justice within a developing world context, and in formal retail areas, and aims to set out ways in which land use management can be made more relevant; both for South African cities and cities in other developing countries.