Understanding Current and Future Fragmentation Dynamics of Urban Forest Cover in the Nanjing Laoshan Region of Jiangsu, China

Abstract

Accurate acquisition of the spatiotemporal distribution of urban forests and fragmentation (e.g., interior and intact regions) is of great significance to contributing to the mitigation of climate change and the conservation of habitat biodiversity. However, the spatiotemporal pattern of urban forest cover changes related with the dynamics of interior and intact forests from the present to the future have rarely been characterized. We investigated fragmentation of urban forest cover using satellite observations and simulation models in the Nanjing Laoshan Region of Jiangbei New Area, Jiangsu, China, during 2002–2023. Object-oriented classification-based land cover maps were created to simulate land cover changes using the cellular automation-Markov chain (CA-Markov) model and the state transition simulation modeling. We then quantified the forest cover change by the morphological change detection algorithm and estimated the forest area density-based fragmentation patterns. Their relationships were built through the spatial analysis and statistical methods. Results showed that the overall accuracies of actual land cover maps were approximately 83.75–92.25% (2012–2017). The usefulness of a CA-Markov model for simulating land cover maps was demonstrated. The greatest proportion of forest with a low level of fragmentation was captured along with the decreasing percentage of fragmented area from 81.1% to 64.1% based on high spatial resolution data with the window size of 27 pixels × 27 pixels. The greatest increase in fragmentation (3% from 2016 to 2023) among the changes between intact and fragmented forest was reported. However, intact forest was modeled to have recovered in 2023 and restored to 2002 fragmentation levels. Moreover, we found 58.07 km2 and 0.35 km2 of interior and intact forests have been removed from forest area losses and added from forest area gains. The loss rate of forest interior and intact area exceeded the rate of total forest area loss. However, their approximate ratio (1) implying the loss of forest interior and intact area would have slight fragmentation effects on the remaining forests. This analysis illustrates the achievement of protecting and restoring forest interior; more importantly, excessive human activities in the surrounding area had been avoided. This study provides strategies for future forest conservation and management in large urban regions.

Effect of the Grain‐for‐Green Program on forest fragmentation

“…Compared with conventional assignment modeling, our program reduces the possibility of user error and increases the repeatability of accurate results without transferring data or models between various software applications (Moulds et al, 2015). The results provide a ref- then remains unchanged with increasing neighbourhood sizes (Figure 6), which is inconsistent with the findings of previous studies (Kowe et al, 2020;Noh et al, 2022;Shen et al, 7). We believe that the distribution of forest patterns is also one of the factors impacting the scale effect of FAD; a specific impact assessment requires further exploration.…”

“…The FAD method (Riitters et al, 2002; has been regarded as the most effective means characterizing forest fragmentation (FAO, 2020;Vogt et al, 2022), and it has been applied to forest fragmentation research at the national, regional, and provincial scales (Noh et al, 2022;Osewe et al, 2022;Rosan et al, 2022;Shen et al, 2020;Wang et al, 2020). However, there are few relevant studies on the application of this method at the county scale.…”

“…The FAD value is sensitive to changes in moving window size, and selecting an appropriate window size can balance the uncertainty of the final level of forest fragmentation. (Shen et al, 2020).…”

“…Furthermore, it will help reveal the evolutionary mechanism of different forest types in different ecological environments by elucidating the spatial process and quantitatively describing the method of forest fragmentation (Sharma, Chakraborty, et al, 2017; Sharma, Robeson, et al, 2017). The FAD method (Riitters et al, 2002; Riitters & Wickham, 2012) has been regarded as the most effective means characterizing forest fragmentation (FAO, 2020; Vogt et al, 2022), and it has been applied to forest fragmentation research at the national, regional, and provincial scales (Noh et al, 2022; Osewe et al, 2022; Rosan et al, 2022; Shen et al, 2020; Wang et al, 2020). However, there are few relevant studies on the application of this method at the county scale.…”

Assessing Land Cover and Ecological Quality Changes under the New-Type Urbanization from Multi-Source Remote Sensing

“…As an urban fringe of Nanjing city, the JBNA has lagged behind the development of the main city area on the opposite bank of the Yangtze River since before 2015. Due to its unique location at the intersection between the Yangtze River Economic Belt and the Eastern Coastal Economic Belt of China, the JBNA is a vital gateway of the Yangtze River Delta to drive the development of the middle and upper reaches of the Yangtze River [12]. Thus, an assessment of the impacts of the two types of urbanization processes on the changes in LC and ecological quality in the JBNA pioneer area will have important practical significance for governmental departments to take active countermeasures to achieve the goals of environmental protection and sustainable economic and social development, which are NTU requirements.…”