Biodiversity Has Been Maintained with Intermediate Disturbance in Traditional Agricultural Lands

Authors

  • Kei Uchida,

  • Atushi Ushimaru


All photos by Kei Uchida, except as noted.

Richness and diversity of plant and herbivorous insect species were significantly lower in abandoned and intensified grasslands than in traditional grasslands. This trend was consistent throughout the seasons in 2011 and 2012. Changes in mowing frequency and surrounding landscape due to land abandonment and intensification explained plant richness declines around paddy terraces. Declines in herbivorous insects were well explained by plant richness declines and changes in mowing frequency. Plant and herbivore richness were maximized at an intermediate mowing frequency (about twice per year), which is a typical practice on traditional terraces.

Figure Photo 1.

In the study area, semi-natural grasslands have been maintained on the levees of paddy fields and irrigation ponds around agricultural lands by periodic mowing.

Figure Photo 2.

Many butterfly species and orthopteran species live in semi-natural grasslands around paddy fields. Upper: Lycaena phlaeas on Senecio integrifolius subsp. Fauriei. Middle: Nephargynnis anadyomene on Cirsium japonicum. Bottom: Gonista bicolor on Miscanthus sinensis.

Figure Photo 3.

During recent decades, changes in human management have changed traditional species-rich agricultural lands into species-poor abandoned and intensified lands.

Upper left photo by A. Ushimaru is from the article “Topography- and management-mediated resource gradients maintain rare and common plant diversity around paddy terraces,” in Ecological Applications 23:1357–1366.

Figure Photo 4.

This study indicates that the richness of plants, especially perennials, plays an important role in maintaining herbivorous insects in semi-natural grasslands around paddy terraces. Upper, Platycodon grandiflorus; middle, Cirsium sieboldii; bottom, Aster rugulosus.

These photographs illustrate the article “Biodiversity declines due to abandonment and intensification of agricultural lands: patterns and mechanisms,” by Kei Uchida and Atushi Ushimaru, tentatively scheduled to appear in Ecological Monographs 84(4), November 2014. http://dx.doi.org/10.1890/13-2170.1

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