Effects of Biofuel Production on Biodiversity

Production of biofuel is expected to increase to 135 million cubic meters by 2022, which would require about 100,000,000 ha of land to grow the necessary feedstock (Perlack et al. 2005).  Such a large amount of land committed to biofuel feedstock production is likely to have a significant negative effect on local and surrounding biodiversity as crop diversity decreases and pest arthropods proliferate (Cook et al. 1991).  Insects are the largest group of organisms on Earth, comprising approximately 1 million described species (Anonymous 2011).  Plants and moths have a mutual reliance on one another.  Moths rely on plants for food and breeding purposes, and plants rely on moths as their pollinators. (Reynolds et al. 2009; Yoder et al. 2010).  In addition, adult moths are an important source of food within the food chain, and, therefore, any decline in their numbers or diversity could lead to further problems within the ecosystem (Whitfield & Wagner 1991).  As the growing production of biofuel disrupts biodiversity, Harrison and Berenbaum (2012) aim to determine the impact of non-corn feedstock production on the diversity of moths.  One of their main concerns is that the increased feedstock production will decrease the abundance and diversity of native prairie plants in Illinois, thereby decreasing the diversity and population of arthropods. Shelby Long
Harrison, T., Berenbaum, M., 2012.  Moth diversity in three biofuel crops and native
prairie in Illinois.  Insect Science. DOI: 10.1111/j.1744-7917.2012.01530.x

Harrison and Berenbaum of the University of Illinois at Urbana-Champagne investigated the impact of non-corn feedstock production on moth species diversity.  They planted 7 sites in Illinois, each site varying in size and shape.  Each site supported plant species adapted to live in the mesic prairie.  The University of Illinois site south of Savoy included 6 of each type of plot of switchgrass, miscanthus, mixed miscanthus, vetch, and corn.  At the University of Illinois Energy Biosciences Institute (EBI) Energy Farm site they planted four plots of each treatment of switchgrass, miscanthus, corn, and mixed prairie.  At the Agricultural Centers of DeKalb, Dixon Springs, Fairfield, Brownstown, and Orr they planted 8 alternating plots of miscanthus and switchgrass, which were both adjacent to large cornfields.  In order to collect samples, researchers used an 18.9-L bucket trap with an 8-watt ultraviolet light, placing the traps in the center of each plot.  Researchers identified moth species by sight and genital dissection.  Collections were taken from one of each plot type on the same night within the sites.  Samples were collected from the Savoy site ten different nights in 2007, two nights in 2008 and one night in 2009 at the EBI Energy Farm site, and one night from the Agricultural Centers of DeKalb, Dixon Springs, Fairfield, Brownstown, and Orr in 2009.  In order to determine the alpha diversity within the crops they used the Shannon-Wiener index and to determine the beta diversity researchers used the Sorenson’s index.  Alpha diversity refers to the diversity of species within a local habitat, in this case within the plots, and beta diversity compares the diversity of species between different habitats, in this case between the plots. 

Over the course of Harrison and Berenbaum’s (2012) study, 5,411 total moths, 252 species, and 25 families were collected.  Based on 2007 data collection, researchers determined that alpha diversities were similar among all crops and beta diversities were low.  After analyzing the 2008 collections they determined that alpha diversity of moths was high within the prairie and low within miscanthus and corn.  Beta diversity was lowest in praire x switchgrass and miscanthus x switchgrass and highest in corn x miscanthus.  In 2009, researchers calculated alpha diversity to be highest in prairie and switchgrass.  Overall, Harrison and Berenbaum (2012) found in 2008 and 2009 the highest level of moth diversity to be in prairie plants, second highest in the switchgrass, and lowest in the corn and miscanthus.  Therefore, their results are consistent with previous studies showing that more diverse native prairie plant abundance leads to a higher diversity of arthropods than in monocultures of annual plants such as soybeans and corn (Bianchi et al. 2006).  Harrison and Berenbaum indicated that their data are generally consistent with the previous studies; however, they suggest that any inconsistencies present are a result of the small sampling size, close proximity of the plots, and low species counts, which tend to skew the calculations. Harrison and Berenbaum recommend that further research be done in order to determine the most efficient methods to manage agricultural fields being used for biofuel feedstock production.       

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