Dead tree branches in urban forests and private gardens are key habitat components for woodpeckers in a city matrix

Abstract

Populations of saproxylic organisms, i.e. species that are dependent on dead or decaying wood, in urban ecosystems are limited because dead wood is regularly removed for safety and aesthetic reasons. However, depending on management policies and property ownership, a small amount of dead wood debris may be occasionally left in situ during maintenance work. As a result, some wooded habitat patches within an urban matrix might host such organisms. This study aimed to evaluate the importance of three principal habitat types (municipal greenery, private gardens and forest remnants) for woodpecker species richness and abundance in an urban ecosystem and to distinguish the role of dead wood forms available therein (fallen logs, snags and dead tree branches). The breeding assemblage of woodpeckers together with dead wood resources were surveyed in the city of Kraków (southern Poland). Eight woodpecker species were recorded within the urban matrix and 75% of the sample plots were occupied by at least one species. The occurrence of five of the species was positively related to forest remnants or private gardens, whereas the occurrence of three species exhibited no clear relationship with the availability of a specific greenery type. Woodpecker species richness was correlated with the availability of snags in forest remnants and dead tree branches in private gardens, while woodpecker abundance was correlated with the availability of snags and dead tree branches in forest remnants, and dead tree branches and large old trees in private gardens. In conclusion, private gardens and forest remnants are important habitats for woodpeckers in an urban matrix. Dead tree branches, snags and large old trees may constitute an important habitat component for saproxylic organisms in an urban ecosystem and may help to sustain biodiversity in urban areas. An understanding of the habitat requirements of dead-wood dependent species within an urban landscape could be useful in the conservation of local populations of such organisms, for which the preservation of dead wood resources should be included in urban landscape planning and green space management.