Diversity of airborne arthropods in a silvoarable agroforestry system.
The diversity and abundance of airborne arthropods in a silvoarable agroforestry system with associated forestry and arable control areas in northern England was investigated with yellow water-pan traps. The agroforestry system consisted of alleys of arable crop (peas) separated by production hedges of 3-year-old furniture-timber trees (ash [Fraxinus], cherry [Prunus], sycamore [Acer pseudoplatanus] and walnut [Juglans]) and hazel [Corylus] bushes. The most common taxa were more abundant in the agroforestry system than in the adjoining arable control area containing the same arable crop. The diversity of aerial arthropods as measured by the log-series index was also higher in the agroforestry system than in the arable control area. Comparison of diversity around one tree species, sycamore, showed that trees grown at forestry density were better able to provide higher arthropod diversity at the beginning of the cropping season whereas those in production hedges were better later in the cropping season. Studies on the population dynamics of insect pests and their natural enemies in the pea crop suggested that the production hedges can play an important part in attracting and maintaining populations of natural enemies close to an adjacent arable crop.