The effect of maize cultivation on invertebrate biodiversity
Norris, S.L. (2015) The effect of maize cultivation on invertebrate biodiversity. Doctoral thesis, Harper Adams University.
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Abstract
Agriculture is being challenged to provide food, and increasingly fuel, for an expanding global population (Werling et al., 2014). Row crop agriculture threatens long-term food security through conversion of natural and semi-natural habitats to arable land (Clay et al., 2014; Wodika and Baer, 2015). Land use change from natural to agricultural is well known to reduce genetic diversity, enhancing atmospheric gas emissions, accelerating soil erosion and reducing water quality (Tiemann et al., 2015; Clay et al., 2014 ). Biodiversity loss is an important consequence of agricultural intensification and can lead to reductions in agroecosystem functions and services (Bardgett and Van der Putten, 2014; Tiemann et al., 2015; DeFries et al., 2004; Tsiafouli et al., 2015). This thesis investigates contrasting maize cultivation techniques to understand how these changes in agricultural practice affect above-below ground invertebrate interactions. Positive impacts of above-ground biodiversity on below-ground communities and processes have primarily been observed in natural systems (Caruso et al., 2012; Scherber et al., 2010; Tiemann et al., 2015). However, these theories can be applied to agricultural systems to increase inter-species interactions between plants and invertebrates (Briones and Bol, 2003; Tiemann et al., 2015; Wodika and Baer, 2015). This study uses literature surrounding grassland above- and below-ground interactions to understand why arthropod communities in conventional maize cultivation systems exhibit poor biodiversity (Wardle et al., 1999; Saviozzi et al., 2001; Firbank et al., 2003; Groom et al., 2008; Scherber et al., 2010). 1.1. Hypotheses, aims and objectives In this thesis, the effect of different maize cultivation techniques on invertebrate biodiversity was assessed. The goal was to gain an accurate understanding of the effects of maize cultivation and ground cover management practices on above- and below-ground invertebrate biodiversity, functionality and resource use. H1= reduction in physical disturbance would increase the biodiversity of below-ground invertebrates H1= reduction in physical disturbance would increase the biodiversity of above-ground invertebrates 2 H1= Increasing non-crop richness increases below-ground invertebrate biodiversity H1= Increasing non-crop richness increases above-ground invertebrate biodiversity H1= Increasing non-crop cover increases below-ground invertebrate biodiversity H1= Increasing non-crop cover increases above-ground invertebrate biodiversity H1= Above- and below-ground invertebrates derive carbon from dominant vegetation 1.2. General conclusions The findings from this thesis highlight that grassland communities have a greater richness than maize cultivation systems. Conventional maize cultivation was found to have fewer taxonomic groups than the more stable grassland system. Functional niches within each system were comprised of different taxa. The below-ground invertebrate communities within each system consumed carbon that was derived from the dominant vegetation, although the isotopic signature of the maize community was diluted. This work was used to inform a more detailed field study regarding the effects of different maize cultivation techniques on invertebrate biodiversity in which soil preparation and ground cover management was altered. Reduced disturbance and increases in non-crop vegetation in the different maize cultivation systems was shown to improve invertebrate diversity and change community composition. Changes in above- and below-ground community composition were found to be strongly linked to changes in vegetation richness and litter. This linkage via changes in ground cover management between the above- and below-ground communities demonstrates that although both were influenced by changes in vegetation richness, variation in litter composition was the predominant driver of β-diversity. However, for the first time it has been shown that the above- and below-ground communities responded differently to increases in the cover of litter. The above-ground β-diversity was found to increase with greater litter cover, but differences in below-ground β-diversity reduced with increases in litter. Overall, above-ground communities were found to be more disturbed than the below-ground communities; for the first time this has been identified as a link between the size 3 distributions of the above- and below-ground invertebrates, where smaller biomass taxa at greater densities were able to respond quickly to disturbance. This showed that below-ground invertebrate communities were better able to recover from disturbance events and retain important ecosystem services. This thesis has used innovative statistical techniques which has shown that the size distribution of predators within the above- and below-ground communities link the respective food webs, with the smaller bodied generalist predators being better able to feed in both the below-ground mainly detrital food web and the above-ground mainly herbivorous food web.
| Item Type: | Thesis (Doctoral) |
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| Divisions: | Crop and Environment Sciences (to 31.07.20) |
| Depositing User: | Ms Kath Osborn |
| Date Deposited: | 18 Nov 2018 14:56 |
| Last Modified: | 18 Nov 2018 14:56 |
| URI: | https://hau.repository.guildhe.ac.uk/id/eprint/17357 |
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