Conservation of Flower-arthropod Associations in Remnant African Grassland Corridors in an Afforested Pine Mosaic

Abstract

While there has been much debate on the role of landscape corridors or linkages for animal movement and residency, there is little information on their role in maintaining ecological associations. We assess here the arthropod assemblages on flowers, seed heads and leaves of indigenous plants in a network of remnant grassland corridors across an alien pine-planted landscape in southern Africa. The results showed that the arthropod-plant (flowers, seed heads and leaves) associations remained, and were mostly quantitatively similar throughout the network of corridors. Narrow corridors (20–100 m wide) deep within the plantation-grassland mosaic still had high biodiversity value. The most threatening factor to flower-arthropod associations was disturbance, particularly cattle grazing. That the host plants were actually present was, in itself, an indicator that disturbance nevertheless was low. The associations are only lost when the plants are lost, and not when the plants are present but under some disturbance pressure. Although these corridors, which amount to about a third of the total area, mitigate the effects of pine afforestation, they can also be conduits for heavy human impact. This means that these corridors, even narrow and deep ones, are only of maximum value when there is minimal anthropogenic impact.