Pollinator biodiversity and interaction networks in anthropogenic systems - roadside verges and transmission line easements as pollinator habitat in Manitoba, Canada

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Martini, Massimo
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The loss of natural and semi-natural habitats resulting from human activities is a global driver of wild pollinator declines and disruption of mutualistic plant-pollinator networks. Despite the negative effects of landscape conversion on biodiversity, green spaces within anthropogenic systems – including road verges, powerline easements, crop margins, and city parks – may be managed to serve as refuge habitats for insect pollinators. Road and powerline rights-of-way (ROWs) are widespread, long linear areas that connect and intersect multiple habitats, and are composed of vegetation that is continuously maintained in an early-successional state. Successful management requires detailed ecological information, but significant gaps exist in understanding how ROWs can benefit plant-pollinator communities and interactions. I investigated the effects of various local and landscape-level variables on pollinator communities and plant-pollinator networks within ROWs across sub-taiga Manitoba, Canada, to inform management for conserving wild pollinators and network functionality. Over two years, I recorded 9,190 bees, flies, and wasps foraging on flowers within 18 road verges and along a 300 km section of a major north-south powerline easement. Using generalized linear mixed-effects models, I found that blooming plant richness and abundance had positive effects on pollinator biodiversity in the powerline, but not in the roadsides, possibly due to the weedy nature of the latter. ROWs located within landscapes with a greater proportion of natural or semi-natural land hosted greater biodiversity. I found contrasting effects of landscape diversity, which had positive effects on pollinator biodiversity in the road verges, but negative effects in the powerline. The latter effect was region-dependent, probably due to the different identity of the dominant land-cover types between ecoclimatic regions. Finally, I found that integrated vegetation management allowed the powerline ROW to host more biodiverse and robust pollination networks. My results show that roadside verges and powerline easements in Manitoba are harbouring significant biodiversity of insect pollinators, including several rare or uncommon species that were previously unknown from the province, and one which had never been described before. My findings confirm that these ROWs have a considerable conservation potential, as they can host biodiverse and resilient plant-pollinator communities within Manitoba’s disturbed and homogeneous landscapes.
pollinators, biodiversity, powerline corridor, roadside verges, pollination networks, habitat management, right-of-way