Man-made perching sites – electricity pylons accelerate fleshy-fruited plants succession in farmlands

Abstract

Electricity pylons and power lines in an agricultural environment serve as artificial perching sites for many birds. For this reason, seeds of fleshy-fruited plant species are predominantly deposited in these places. In the present study we show that electricity pylons may play an important role in the succession of fleshy-fruited shrubs and trees in intensive farmland. The aim of the study was to evaluate the importance of electricity pylons as artificial perching sites and thus as important locations enabling earlier succession and colonisation by fleshy-fruited plant species. The study was conducted during June and July 2013 in the Wielkopolska province of western Poland in intensive farmland with numerous small isolated forest patches. In total, we found 22 fleshy-fruited and 10 dry-fruited tree and shrub species under electricity pylons, of which 30% were alien species. The density of fleshy-fruited species under pylons was significantly higher in comparison with control plots, in which 85% of tree and shrub species were alien species. Padus serotina and Sambucus nigra were the species most frequently found under pylons. Plants of non-endozoochorous origin (i.e. anemochorous Pinus sylvestris, Betula pendula) were fewer in number. As a result, the share of fleshy-fruited species was much greater than those of wind-dispersed pioneer species. This is because fleshy-fruited species are able, thanks to artificial perching sites, to appear earlier than they would under natural conditions, in which these species follow the expansion and development of pioneer anemochorous species acting as natural perching sites. The presence of the electricity pylons compensates for a lack of natural perching sites in a homogenous landscape under intensive agriculture.