The matrix affects trackway corridor suitability for an arenicolous specialist beetle

In conserving regional insect diversity dispersal corridors are advocated to counteract fragmentation and for resilience to climate change. However, influences of corridor design and management on their function are poorly understood. Effects of contrasting matrix structure on the suitability and function of trackways as corridors for dispersal of an arenicolous carabid beetle, Harpalus rufipalpis (Sturm), was studied within a plantation landscape using mark-release-recapture. A total of 1,120 marked H. rufipalpis were released into four trackways: two “open” trackways surrounded by pine plantations aged 13–16 years and two “shaded” trackways surrounded by plantations aged 26–37 years. Dispersal was monitored by a grid of pitfall transects placed across trackways at intervals of four meters, extending 44 m north and south of the release point. Numbers of resident and marked recaptured H. rufipalpis, their average daily movement rates and numbers of recaptures in the north and south direction were compared between open and shaded trackways using 238 recaptures. The surrounding matrix affected trackway suitability with greater abundance of resident beetles found in open trackways; however H. rufipalpis was also naturally present in shaded trackways. H. rufipalpis were more active in low quality shaded corridors as inferred from the greater number of recaptures and from greater daily movement rates. Corridor edge permeability differed between trackway types, with more individuals leaving the corridor to enter the matrix in the less suitable shaded trackways. Thus matrix type affected the potential habitat suitability and conduit function of trackway corridors.