Impact of reserve area on reproduction of a moth‐pollinated Stackhousia Sm. (Celastraceae) species in a fragmented landscape

Abstract

AbstractLandscape disturbance frequently results in reduced pollination and reproduction of animal‐pollinated plants. However, few studies globally, and no studies in Australia, have focused on the impact(s) on plants with nocturnal moth pollinators. This study measured natural levels of reproduction of the common, nocturnally moth‐pollinated plant Stackhousia aspericocca Schuch. ssp. Cylindrical inflorescence (W.R.Barker 1418) (Celastraceae) across a range of reserves of varying sizes within a fragmented landscape of southern Australia. We hypothesized that plant reproduction would show a positive relationship with reserve area. Nocturnal pollinator surveys confirmed that night‐flying settling moths of the families Geometridae and Noctuidae visited flowers of S. aspericocca ssp. Cylindrical inflorescence in the study region, and 8 out of 16 captured, flower‐visiting moths carried more than 100 pollen grains of the study species (overall mean ± SD: 616.69 ± 1155.70). Two individuals of the common geometrid moth Oenochroma vinaria each carried over 3000 pollen grains. Thus, visiting moths may remove and carry large amounts of pollen. In contrast to our initial hypothesis, however, plant reproduction, measured as proportional fruit‐set and mean seed number per fruit, showed no relation to reserve area across two consecutive years, and mean levels of plant reproduction were spatially similar throughout the fragmented landscape of the study region. It is hypothesized that the reproductive resilience of S. aspericocca ssp. Cylindrical inflorescence in the study region is due to effective pollination by common, night‐flying moths, which may utilize both the reserves and their surrounding matrix to complete their life cycle(s).