Monitoring the effects of land consolidation on the ecological environmental quality based on remote sensing: A case study of Chaohu Lake Basin, China

Highlights

• LC made the system undergo a process of “stability-unstable-stable”.

• EEQ reveals long-term convergence, short-term divergence.

• LC can improve the EEQ in the consolidation area and surroundings.

• The interference of the LCPs are the strongest during implementation period.

Abstract

As a kind of activity to break down the original land ecosystem, land consolidation causes the ecosystem to undergo a process of “stability-unstable-stable”. The Chaohu Lake Basin is a typical traditional agricultural planting area and extensive implementation of large-scale land consolidation projects. By monitoring the impact of land consolidation activities in a specific time period in the basin on the project areas and surrounding environment, the spatial and temporal impacts of large-scale land consolidation on regional eco-environmental quality are analyzed. This study mainly monitors crop growth, soil moisture and temperature changes in the land consolidation project area, and the corresponding changes in the surrounding environment. The response of ecological environment factors caused by land consolidation can be embodied in indicators such as humidity, greenness, heat and dryness. Four indicators of NDVI, WET, LST, and NDBSI were selected, using principal component analysis, monitoring the environmental quality changes in the land consolidation areas of Chaohu Lake Basin. Result shows that the ecological environmental quality of the study area exhibits long-term convergence and short-term divergence, and the correlation between the ecological indicators is not significant. The average contribution rate of the first principal component eigenvalue is 67.94 %. The implementation period of the land consolidation project will seriously interfere with the ecological environment, but it can be restored within 3–5 years after implementation, and the ecological environmental quality of the project area will continue to improve. Land consolidation not only can improve the quality of the ecological environment in the consolidation area, but also can promote the surrounding environment. The findings provide theoretical basis and decision guidance for the improvement of land consolidation planning and design (reconstruction) in China, and offer suggestions on strategy-oriented support and scientific basis for promoting the long-term development of land consolidation worldwide.

Introduction

Rural man-land systems involve regional natural processes and human processes, as well as their interactions. Land use change has now entered a high-risk phase in terms of sustainable development goals (Steffen et al., 2015). In order to solve the problem of huge losses of cultivated land caused by urban-rural transformation worldwide (Liu, 2018), implement rural revitalization (Long, 2014), and achieve aesthetically-pleasing ecological civilization construction, land consolidation (LC) is an important tool for rural land system reform that is attaching much attention in both political and academic spheres (Liu et al., 2014a; Liu and Li, 2017; Munnangi et al., 2020; Nguyen and Warr, 2020; Zhou et al., 2020). China has been implementing large-scale LC since the mid-1990s, and the concept of LC was formally presented in 2008. Since then, land consolidation has risen to a national plan (State Council of the People’s Republic of China (SCPRC, 2017) that attempts to protect cultivated land, promote the environment quality of the entire land ecosystem, and improve regional microclimates (Ntihinyurwa et al., 2019). It is widely accepted that LC can improve agricultural infrastructure and land quality, thereby improving agricultural productivity, living conditions (Jiang et al., 2015; Jin et al., 2016), and ecological environmental quality (EEQ) (Shan et al., 2019). In addition, as a land use policy and an issues-oriented type of land engineering, LC can also remedy contaminated and damaged land, improve the regional water and soil environment (Qu et al., 2019), solve the problems of abandoned land (Sikor et al., 2009) and hollow villages (Long et al., 2012), help alleviate poverty (Wang and Li, 2019; Zhou et al., 2019), assist rural revitalization (Li et al., 2014, 2019), and promote sustainable land use and rural development.

Since LC is an activity that breaks down the original land ecosystem, make the ecosystem experienced "stable-unstable-stable" progression, which inevitably has multiple effects on the ecosystem of land consolidation projects (LCPs), including ecosystem components, ecological processes, and surrounding areas. The impact of LC on ecosystem is the influence of project implementation (including construction process and engineering facilities) firstly; secondly the impact on land use structure (diversity, connectivity, combination, etc.); and thirdly, the impact on farmers' production and lifestyle (Jin et al., 2017; Zhang et al., 2014; Zhou et al., 2019). LC influencing biological and ecological environment (Tang et al., 2017), cultivated land ecosystem with the basis of material recycle and energy flow, information exchange function. The large-scale and scattered implementation of LCPs and the future planning and design of LC will exert significant impacts on various cultivated land ecosystem ecological flows (i.e., energy flow, material flow, and information flow).

According to National Land Consolidation Plan and different types of ecological influences, LC can be divided into 5 forms: (1) farmland consolidation (FC), which works on agricultural land (Tang et al., 2019), increasing area of cultivated land, and improving cultivated land quality. (2) well-facilitated capital farmland construction projects (WCFCPs), which are land improvement activities in key areas of rural LC and major projects that focus on capital farmland preservation areas, capital farmland preparation areas, and other regions, and are formed through rural LC and centralized contiguous construction (Yang et al., 2019). WCFC involves the construction of supporting facilities, high and stable yield, good ecological and strong overall resilience, and the construction of capital farmland that is compatible with modern agricultural production and management modes. (3) Land reclamation (LR), which effects on construction land, and disaster damaged land etc., forming cultivated land by reclaiming is the main purpose (Guo et al., 2015a,2015b). (4) Land development, which functions on unused land (Liu et al., 2014a, 2014b), forming new cultivated land by exploitation (Jin et al., 2016; Li et al., 2019). (5) Comprehensive land consolidation (CLC), in which a project may include 2 or 3 consolidation types (Ge et al., 2019), including the above 3 forms. In terms of the consolidation process, disturbances from engineering construction during the implementation period significantly affect the ecological environment of the project area (Lisec and Pintar, 2005; Liu et al., 2013; Wang et al., 2014). After project construction is complete, the recovery of soil function, production capacity, and the environment takes time (Muchová et al., 2016; Wang et al., 2011), with some researchers believing that this process generally requires 3–5 years (Guo et al., 2015a,2015b). Upon reaching a certain stage of recovery, the agricultural production capacity and EEQ will have generally improved in the project area such that the LC will then exert less impact on the ecosystem than climate or other factors (Kolis et al., 2017).

The influence of the regional ecological environment is systematic and integral. Various types of LCPs have been implemented on the mesoscale, which is helpful for observing the spatial and temporal differences of different kinds of LC projects. This study utilized the Chaohu Lake Basin as a study case, identified and measured the EEQ of the cultivated land ecosystem using remote sensing (Hong et al., 2017) in the typical LCP areas, and explored the mechanism process and route of the direct impacts on the cultivated land ecosystem. We analyzed the regional spatiotemporal regular patterns of the ecological effect of the LCPs, evaluated the effect of LC on the efficiency of the cultivated land ecosystem, and identified the area with lower consolidation efficiency. This investigation determined the method for optimizing LCP location and planning. LC ecological environmental monitoring not only can provide significant references for effective solutions to the ecological problems in LCP areas but can also promote the benign interaction of regional socioeconomic-ecological development (Cheng et al., 2019; Hasituya et al., 2016). Ecological LC is a specific process each country must address and a key path to sustainable development (Yan et al., 2015; Zhang and Zhao, 2007). This research can provide theoretical basis and decision guidance for perfecting the LC planning and design (reconstruction) of China, and offer suggestions on strategy-oriented support and scientific basis for promoting the long-term development of LC worldwide.