Cascading impacts due to the invasive alien tree species, Robinia pseudacacia in the Czech Republic
It is well known that invasive alien species can cause negative ecological impacts both above and below-ground. However, impacts which perpetuate along food-chains are less well studied with few examples existing. The impact of Robinia pseudoacacia (Fabaceae) on bird species richness due to habitat structure and alteration of food webs was studied in the Czech Republic. Twenty plots of native tree species were compared to 19 plots of the invasive R. pseudoacacia. At each of the plots bird populations were surveyed (visually and acoustically) in 2014, during three visits during the peak breeding season. Moths (Lepidoptera) were considered as an indicator of food supply for birds and were sampled using light traps on an individual night of each month from April to November at each plot. Both birds and moths were identified to species level. Birds were classified into habitat generalists or specialists. R. pseudoacacia plots had a lower species richness of habitat specialist birds, a higher species richness of habitat generalist birds and a lower diversity of moth species compared to native plots. In addition, moth diversity was related to the species richness of habitat specialist birds whereas species richness of habitat generalist birds was only related to habitat structure. Therefore, this study provides evidence that specialist birds were limited by a less diverse food supply in the invaded stands.
Sources
Reif J, Hanzelka J, Kadlec T, Štrobl M, Hejda M (2016) Conservation implications of cascading effects among groups of organisms: The alien tree Robinia pseudacacia in the Czech Republic as a case study. Biological Conservation 198, 50-59.