Abstract
AbstractThere is an urgent need to identify ways of managing agricultural landscapes for biodiversity conservation without reducing food production. Farming practices that consider spatio‐temporal heterogeneity of farm fields may be a feasible alternative to large‐scale revegetation of farmlands for maintaining arthropod biodiversity and their important ecological function. We examined seasonal differences in beetle assemblages in woodland remnants and four adjoining farmland uses in a highly modified agricultural landscape in southeastern Australia. The farmland uses were crops, fallows, and two restoration treatments (fine woody debris applied over harvested crop fields, and restoration plantings). Unexpectedly, overall species richness was significantly lower in remnants than in adjacent farmlands. Remnants and farmlands supported significantly different assemblages, with a third of species found in both habitats. Abundance responses were taxon‐specific and influenced by interactions between land use and season. In particular, predator abundance was significantly higher in plantings and fallows during spring compared to summer. Detritivore abundance was significantly higher in the woody debris compared to the adjacent remnants. Herbivore abundance did not differ between remnants and farmlands over time. Complex responses provide strong support for a mosaic of land uses to effectively conserve different beetle groups. Species richness results suggest that further agricultural intensification, in farm fields and through the removal of remnant vegetation, risks reducing beetle diversity in this region. Maintaining farmland heterogeneity with a mix of low‐intensity land uses, such as conservation tillage, crop–fallow rotation, restoration plantings, and the novel application of fine woody debris over cultivated fields, may provide seasonal refuge and resources for beetles.
Highlights
Agriculture is a major cause of decline in biodiversity and ecosystem services globally (Bradshaw 2012, Newbold et al 2015, Soliveres et al 2016), due to widespread conversion and degradation of natural habitats (Gibson et al 2011, Tilman et al 2011) and increased intensification of agricultural practices (Benton et al 2003, Hendrickx et al 2007, Attwood et al 2008)
This is because higher species richness and abundance of many taxonomic groups are typically found in semi-natural habitats than in intensive land uses due to higher habitat heterogeneity and resource and niche availability associated with undisturbed, natural vegetation (Benton et al 2003, Fischer et al 2006, Attwood et al 2008)
Our findings contribute to growing evidence that effective conservation of arthropod diversity needs to consider entire landscape mosaics (Benton et al 2003, Tscharntke et al 2005, Bennett et al 2006, Vasseur et al 2013) as well as maintain farmland heterogeneity with a mix of low-intensity land uses (Bennett et al 2006, Kleijn et al 2011, Uchida and Ushimaru 2014), such as conservation tillage, crop–fallow rotation, and restoration plantings
Summary
Agriculture is a major cause of decline in biodiversity and ecosystem services globally (Bradshaw 2012, Newbold et al 2015, Soliveres et al 2016), due to widespread conversion and degradation of natural habitats (Gibson et al 2011, Tilman et al 2011) and increased intensification of agricultural practices (Benton et al 2003, Hendrickx et al 2007, Attwood et al 2008). While biodiversity conservation has traditionally focused on species associated with patches of remnant native vegetation, there has been growing emphasis on the effect of spatial heterogeneity of the overall landscape on species distribution and assemblages (Fahrig and Nuttle 2005, Turner 2005, Vasseur et al 2013). Intensively managed farm fields—such as crop monocultures, which typically form the bulk of agricultural landscapes—have been suggested as important drivers of population dynamics and persistence due to their “hidden” habitat value in space and time (Vasseur et al 2013) This hidden heterogeneity refers to the diversity in management practices and crop types, as well as more subtle changes in crop fields within and between growing seasons. The effects of fine-grained spatio-temporal changes of farm fields on the structure of biotic communities, have been rarely studied (Gagic et al 2012, Vasseur et al 2013, Puech et al 2015)
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