To maximize the ecological services of urban forests, a better understanding of the effects of urbanization on urban forest characteristics, landscape metrics, and their associations is needed for landscape-related regulations in space-limited green infrastructure of metropolitan regions. In this study, Harbin, a typical fast-growing provincial-capital city in Northeast China, is used as a case study. Based on remote sensing images, field surveys, and correlation and variation partitioning analyses, we conclude that landscape characteristics and forest attributes have large variations among different urbanization intensity (UI) regions. Forest patch density (PD), landscape shape index, woody plants species richness, and the Shannon–Wiener index (H′) increased linearly, while stem section area and tree height decreased linearly with the increasing of UIs. UI had a greater influence on tree size and forest community attributes than the forest landscape pattern. Accordingly, any landscape regulation on forest attributes should be implemented according to UIs. In addition, Euclidean nearest neighbor distance(ENN-MN), mean perimeter-area ratio (PARA-MN), fractal dimension index(FRAC-MN), and PD could probably indicate forest attributes the most, e.g., the increase of PARA-MN may be accompanied with taller trees in low and heavy UI regions, but lower woody plants species evenness in low and medium UI regions. More diversified woody plants species, and afforested areas should be advocated in a low UI region, while in a heavy UI region, the conservation of large trees should be implemented. Our results highlight that the implementation of urban forest management should vary according to different urbanization regions to maximize ecological services.
Using the UN Comtrade database and multiple sources of agricultural investment data, this paper outlines the emerging patterns of food trade and agricultural investment between Southeast Asian countries and China. The paper shows that China has adopted a flexible overseas food strategy. First, China has increased food export and shifted its food trade with Southeast Asia from a dependent relationship towards a complementary relationship at the regional level in recent years. Second, China tends to adapt to the existing conditions of food production and trade in Southeast Asian countries instead of fundamentally altering them. Finally, Chinese overseas agricultural investment is less driven by domestic food demand but more oriented for profit making, and this gives it flexibility in diversifying investment. An adequate understanding of China’s flexible food strategy in bilateral and multilateral relationships holds implications for global food security. 相似文献