4.1 How urban-rural integration affects the landscape pattern
Urban-rural integration constitutes a transformative process with profound implications for landscape composition and structure. Our research in Changsha metropolitan area has shed light on the diverse urban-rural integration indicators and their distinct influences on various landscape pattern metrics. Understanding the primary drivers and processes behind the observed alterations in landscape patterns is paramount.
Upon analyzing the impact of urban-rural integration on the percentage of landscape, we discovered that the development of high-value agriculture plays a crucial role in stabilizing agricultural and ecological landscapes. Additionally, an increase in small town density emerged as a potent deterrent against the reduction of agricultural landscapes. Conversely, factors such as increased investments in agriculture, improved traffic, enhanced agricultural mechanization, and a narrowed urban-rural income gap were associated with a decrease in both agricultural and ecological landscapes. Previous studies have also highlighted that increased mechanization and the subsidized intensification of agriculture contribute to the loss of semi-natural habitats (Robinson and Sutherland 2002). Moreover, an increase in income is indicative of declines in vegetated areas and forest coverage (Su et al. 2014).
The analysis of urban-rural integration's impact on landscape fragmentation has revealed several key insights. Increased investments in agriculture, enhanced rural labor productivity, and progress in agricultural mechanization collectively serve as effective measures against excessive landscape fragmentation. Moreover, an increase in small town density contributed to the reduction of fragmentation in ecological landscapes. However, the non-agriculturalization of labor and the intensification of urban-rural road networks, while fostering higher rural residents' income, exacerbate the fragmentation of both agricultural and ecological landscapes. Mechanization often leads to the consolidation of small and fragmented farmland into large-scale farms (Liao et al. 2022). Conversely, when households become less reliant on agriculture, farmland is more likely to undergo fragmented (Wang et al. 2020). Additionally, roads are identified as a major contributor to habitat loss, fragmentation, and degradation (Van Der Ree et al. 2011).
The impact analysis of urban-rural integration on the mean shape index underscores that an increase in rural household incomes and rural investments has led to a diminishing complexity of agricultural and ecological landscape patches. Conversely, the growth of small towns has proven advantageous in maintaining the complexity of habitat patch shapes. This is consistent with the view that landscapes altered by resource exploitation or development tend to exhibit patches with simpler shapes (Krummel et al. 1987; Forman 1995). Additionally, the influence of urban-rural integration on the connectance of landscapes indicated that factors such as rural investment, enhanced rural labor productivity, agricultural mechanization, development in high-value agriculture, and small town growth played crucial roles in promoting the connectance of agricultural and ecological landscapes. Simultaneously, agricultural mechanization, traffic improvement, and rural investments contribute to enhancing the connectance of urban-rural construction landscapes. Previous studies have noted that urban-rural connectivity in Asia is often linked to increases in overall agricultural inputs and output. Enhancing rural-urban connectivity could theoretically influence agricultural sustainability by boosting farm productivity in urbanizing regions (Boudet et al. 2020).
Furthermore, the analysis of urban-rural integration's impact on landscape diversity revealed that enhancing non-agricultural employment and increasing incomes contributed to an increase in landscape diversity. However, factors such as agricultural mechanization, the development of high-value agriculture, and increased rural investments limited landscape diversity. This finding has been confirmed by other studies on relationships between jobs, incomes, social diversity, agricultural mechanization, and crop diversity (Garibaldi and Pérez-Méndez 2019; Daum et al. 2023; Palacios et al. 2013).
4.2 Mechanism of how urban-rural integration impacts landscape pattern
During the process of advancing urban-rural integration, various factors and processes, including societal convergence, economic interaction, technology sharing, and spatial interlinkage, induce diverse changes in the landscape pattern. Firstly, urban-rural economic coordination, encompassing initiatives such as increasing rural investment, reducing the urban-rural productivity gap, and developing high-value agriculture, plays a crucial role in controlling reduction, enhancing connectivity, mitigating fragmentation, maintaining the complexity of agricultural and ecological landscapes, as well as preventing the fragmentation of constructed landscapes, despite a decrease in landscape diversity. Investments in agriculture and improvements in agricultural productivity contribute to expanding agricultural production, enhancing farmland quality, and promoting agricultural specialization and intensification (Frison and IPES-Food 2016). This, to some extent, protects agricultural landscapes, improving their regularity and connectivity (Boudet et al. 2020). Landscape changes resulting from adjustments in agricultural structure are also evident under specific investment and production conditions. Focusing on high-value crops, for instance, allows farmers to alleviate pressure on converting natural landscapes, like forests or wetlands, into agricultural land. Additionally, diversifying crop types and cultivating agroforestry systems positively impact the complexity of agricultural landscapes (Asbjornsen et al. 2014; Wilson and Lovell 2016; Sirami et al. 2019). Moreover, when more investments are directed towards village revitalization and infrastructure development, it simultaneously leads to increased intensity of urban and rural construction (Jiang et al. 2013), while also controlling the occupation of construction on agricultural and ecological landscapes.
In contrast, societal convergence, characterized by the increase in non-agricultural employment among rural residents and the reduction of the urban-rural income gap, leads to a decrease in the proportion, connectivity, and complexity of agricultural and ecological landscapes, as well as an increase in landscape fragmentation, while promoting landscape diversity. This occurs because rural households engaged in non-agricultural activities not only directly alter agricultural production methods (Li et al. 2021), such as the abandonment of cultivated land, but also boost rural household incomes. This increases the likelihood of landscape-disturbing activities, such as altering land usage, transitioning it into non-agricultural purposes, and constructing new residences, among others (Wang et al. 2020; Zhang et al. 2016). Additionally, this shift can lead to the adoption of new lifestyles and values, influencing the landscape through changes in consumption patterns, community development, and various other aspects.
Furthermore, the role of agricultural mechanization in reducing landscape fragmentation and enhancing landscape connectivity, as well as the decline in landscape diversity, to some extent characterized the two-way impact of technology sharing on landscapes in the process of urban-rural integration. The agricultural mechanization process often requires an increase in the concentration and contiguity of farmland through comprehensive improvements (Daum et al. 2023), thus reducing landscape fragmentation and enhancing landscape connectivity. However, it can also contribute to a decline in landscape diversity, mainly due to shifts towards a singular agricultural planting structure. Besides mechanization, information technology also brings about changes in product production, trade methods, population mobility, and social interactions. In summary, the transfer of knowledge, technology, and information from urban to rural areas during the urban-rural integration process inevitably alters agricultural production methods, fosters innovation, and expedites the transformation of rural society and the economy (de Bruin et al. 2021), has significant implications for the structure of urban and rural regions, and consequently influences the overall landscape patterns.
Additionally, the development of small towns and the improvement of road networks effectively reflect the landscape response process of urban-rural spatial linkage. On the one hand, roads serve as vital bridges connecting urban and rural spaces, significantly enhancing the connectivity of urban and rural construction landscapes. Simultaneously, the construction of road networks often results in conspicuous incisions in the landscape along their routes, leading to landscape fragmentation and a decrease in habitat landscape shape complexity. On the other hand, the development of small towns fosters the concentration of urban and rural populations and spaces. This concentration effectively curbs the expansion of urban-rural construction and reduces human activities' interference in agricultural and natural ecological landscapes. Consequently, it enhances habitat landscape complexity and connectivity. Moreover, some studies suggest that urban-rural spatial linkage often accompanies the emergence and resolution of spatial conflicts (He et al. 2017). In this process, farmlands, forests, and natural areas may be converted into urban and rural development spaces, potentially leading to habitat fragmentation (Liu et al. 2016). This type of landscape pattern change due to urban-rural spatial conflicts is particularly pronounced in peri-urban areas (Ma et al. 2020). These studies further confirm the complexity of the impact of urban-rural spatial linkage on landscape pattern changes.
4.3 Potential implications and integrated governance for landscape sustainability
From the perspective of promoting landscape sustainability, gaining deeper insights into the impacts of urban-rural integration on landscape patterns can significantly enhance its practical value. Landscape sustainability is defined as "the capacity of a landscape to consistently provide long-term, landscape-specific ecosystem services essential for maintaining and improving human well-being" (Wu 2013). Landscape patterns, connecting nature-society relationships to the landscape, play a crucial role in these processes, for better or worse (Wu 2021). However, the discussion on which landscape patterns are more sustainable still needs exploration (Peng 2021). Here, we attempt to infer the potential implications for landscape (un)sustainability, taking into account changes in landscape metrics. We find that the multifaceted urban-rural integration has complex and intertwined impacts on landscape sustainability.
Firstly, urban-rural economic coordination is generally positive for shaping a sustainable landscape pattern. Increased rural investment, the development of high-value agriculture, and the reduction in the urban-rural productivity gap favor the conservation of natural habitat landscapes by reducing encroachment and fragmentation, as well as improving connectivity and complexity. These processes not only contribute to providing more ecosystem services such as Carbon storage and habitat quality, flood control, water quality regulation, and climate regulation (Mitchell et al. 2013; Harrison et al. 2014; Li et al. 2022) but also effectively suppress landscape fragmentation, which can lead to habitat loss and a reduction in species richness (Collinge 1996; Haddad et al. 2015). Complex patch shapes in natural and agricultural landscapes also enhance species richness and encourage animal migration, contributing to landscape resilience and ecosystem balance (Buechner 1989). Unfortunately, the results of our study showed that these economic processes do not significantly promote landscape diversity so as to enhance landscape resilience for better ecosystem balance.
Following our research findings, urban-rural societal convergence did not yield favorable outcomes in shaping a sustainable landscape pattern in contrast to urban-rural economic. Because it resulted in a decrease in habitat landscape proportion as well as an increase in landscape fragmentation. These may pose challenges to biodiversity conservation and ecosystem stability.
The impacts of urban-rural spatial interlinkage and technological sharing on landscape pattern changes are two-fold in the process of creating a sustainable landscape pattern. Agricultural mechanization, while positively contributing to the formation of large habitat patches by reducing fragmentation (Daum et al. 2023), may lead to the homogenization of crop species (Macfadyen and Bohan 2010), making agricultural ecosystems more vulnerable(Sims and Kienzle 2016). Improved urban-rural road networks enhance landscape connectivity but can exacerbate the fragmentation of agricultural and ecological landscapes, leading to biodiversity loss (Bennett 2017; Moser et al. 2002). The positive aspect is that an increase in small town density can effectively preserve various agricultural and ecological landscapes by minimizing disruption and enhancing the complexity and connectivity of habitat landscapes, thereby positively impacting sustainable landscape patterns.
Together, urban-rural integration yields both potentially positive and negative effects on sustainable landscape patterns. Therefore, embracing integrated landscape governance is essential to address the disadvantages of urban-rural integration precisely while strategically leveraging its advantages in various empirical contexts. Landscapes are intricate compositions of land uses, people, and conflicting interests (Ros-Tonen et al. 2015). To promote landscape sustainability, it is crucial to prioritize the conflicting interests among the various stakeholders in both urban and rural areas for improving human well-being (Joan 2014). Establishing a community of interest that spans urban and rural areas proves to be an effective approach to resolving conflicts by bringing together stakeholders with vested interests in a specific landscape. This allows for the identification of individual and collective needs, objectives, and trade-offs and managing them accordingly (Ros-Tonen et al. 2018). This process can be facilitated through various policies related to land resource management, community governance, urban-rural planning, and more.
The policy design of the urban-rural community of interest should prioritize landscape preservation within the context of advancing urban-rural equity objectives. Additionally, it should focus on improving the accessibility of rural areas and expanding opportunities for farmers to access public services and jobs. So, we can strengthen the development of small town to better utilize the potential of small town as nodes connecting rural and urban areas (He et al. 2019). This strategic approach aims to conserve natural ecological landscapes and enhance connectivity based on the mechanistic understanding of how urban-rural integration impacts landscape pattern. Furthermore, policies that encourage the development of high-value agriculture through financial support, technical training, and other means are crucial for promoting urban-rural integration and landscape sustainability. These measures, including small-town construction, rural investment, industrial structure adjustment, agricultural technology improvement, and more, create upward and downward connections between communities, counties, and metropolitan areas. This facilitates the promotion of urban-rural synergy by guiding, regulating, and accommodating multi-stakeholder decision-making. In addition, in order to capitalize on the positive impact of urban-rural interactions on landscapes, it is crucial to establish dependable promotional policies. These policies will enable us to harness better the role of the urban-rural community of interest in constructing a sustainable landscape pattern.
Additionally, we can construct sustainable and multifunctional urban and rural landscapes through integrated landscape planning and management (Rauws and de Roo 2011; Scott et al. 2013). It not only provides protection for critical ecosystem services and a healthy living environment but can also be seen as an effective measure to control the threats imposed by anthropogenic activities in a sustainable way (Peng et al. 2021). Adopting systematic, holistic, and comprehensive approaches to restoration and management enables us to mitigate the damage caused by urban-rural traffic and residential constructions in the original natural ecological patches of the ecological landscape. This includes preventing or repairing habitats that were disrupted during the urban-rural integration process. One viable solution may involve introducing corridors or the installation of more permeable matrix habitats (Metzger and Brancalion 2013). For instance, using rivers, mountain ridges, riverine green belts, and woodland ecological corridor networks to connect isolated ecological patches can form a complete regional ecological safety network. Furthermore, it is possible to establish agroforestry or commercial forestry systems in native forest areas by increasing vegetation types and structural complexity. This can enhance habitat permeability and improve the landscape's urban-rural continuity (Metzger and Brancalion 2013). Contributing to the restoration of degraded rural and urban ecosystems to resemble historical ecosystems in terms of structure, species composition, and ecosystem functioning is also crucial (SER 2004). These measures not only address the adverse impact of urban-rural integration on the landscape pattern but also have the potential to bring about positive social, economic, and environmental changes in both urban and rural areas. Additionally, they promote the coordination and complementarity of urban and rural landscape functions.