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Maintaining forest landscape connectivity is one of the most effective ways to alleviate natural forest fragmentation and biodiversity loss problems. Recently, graph theory based metrics have been used as powerful tools in the assessment of landscape connectivity. However, the functional features of landscape units at different structure levels, based on which outcomes can be enriched and advice can be given for practical applications, have been overlooked. In this study, a series of graph-based connectivity indices was calculated to 1) evaluate the optimal threshold distance, 2) identify the key landscape units at the component and patch levels, and 3) classify the functional types of components and patches and analyze functional patterns at different structural levels. The relationship between patch size and patch functional performance in maintaining landscape connectivity was discussed. With a natural forest area in Minqing County of China as the study area, recommendations regarding forest conservation and connectivity enhancement were provided based on the research conclusions. This study provides a way to comprehensively analyze habitat fragmentation and functional patterns for local forest conservation. [ABSTRACT FROM AUTHOR]

• Priority areas were influenced by habitat proportion and dispersal ability. • The three structural factors explained approximate 80 % of patch importance indices. • Patch size was the primary factor determining the prioritization of patches. • A prioritizing procedure for habitat conservation and management is put forward. Urbanization has resulted in significant habitat loss and fragmentation worldwide, which threats the provision of ecosystem services for human health and life. Maintaining and improving the connectivity of the remnant habitats in and around cities is essential for landscape planning. Landscape metrics have been widely used for modeling and evaluating how landscape structures affect habitat connectivity for different species in many previous studies. However, the results of some previous studies were not consistent and even contradictory. This might limit the applications in practical habitat conservation. In the present study, four actual landscapes with a series of forest cover ratios in Fuzhou City, China, were selected. By using graph-based connectivity indices, the importance of habitat patches for landscape connectivity was explored. The effects of habitat proportion and three patch-level structural factors (i.e. , patch size, shape, and position) on habitat patch importance indices were examined. Our results suggest that habitat proportion governed the overall landscape connectivity. The three structural factors explained approximately 80 % of the variation in the patch importance of connectivity indices. Patch size was the primary factor determining patch importance, while patch location was related to the partition of the three fractions of patch importance. Considering the different roles of the three structural factors played in landscapes with different habitat proportion, the spatial advice for local habitat conservation was proposed. Moreover, general conservation strategies regarding different habitat proportions were provided at the landscape scale and patch scale. Our findings would provide scientific evidence for local decision makers, and could be combined with other conservation planning tools. [ABSTRACT FROM AUTHOR]