Let It Grow Organic Gardens

And I resumed the struggle. -Vladimir

Sunday, September 28, 2008

I Don't Weed; Science Backs Me Up

This from:
Scale Dependent Dispersal and Distribution Patterns of Spiders in Agricultural Systems: A Review
Ferenc Samu. Keith D. Sunderland. Csaba Szinetar
The Journal of Arachnology 27:325–332.

Spider diversity in agroecosytems varies from being impoverished under intensive culture to being, under favorable agricultural management, even greater than in natural habitats.
Harvesting, plowing, pesticide spraying and forest clearcutting are likely to affect most micro-habitats within a given habitat; and they are known to cause severe reductions in spider populations. Conversely, disturbances of intermediate strength and frequency may actually increase the diversity of a spider community. This effect may operate by increasing the diversity of micro-habitats within a habitat.
Interspersed diversification is frequently attained by planting multiple crop species in one field. This in a number of instances resulted in spider densities greater than those found in monocultures, and an associated suppression of pest species. Reduced-tillage systems often provide a diversification of interspersed micro-habitats by engendering a rough or heterogeneous soil surface, plus structural complexity in the form of plant residues conserved from previous-year crops.
In a Swiss orchard, the density of spiders and their webs on the apple trees was greater in plots where weeds had been planted in strips below the trees, than in weed-free control plots. However, in many cases, spider density on and under crop plants is unaffected by strip management, perhaps because spiders aggregate in the favorable micro-habitats (such as weed and flower strips) and do not disperse out onto the crop plants.
The maintenance of grass habitats that are not demolished by crop rotation and the presence of set-aside fields significantly increased the viability of the modeled Lepthyphantes tenuis metapopulation. In asimulated linear landscape the inclusion of small amounts of grassland considerably increased overall spider population sizes.

I am nothing if not a friend to Lepthyphantes tenuis metapopulations.


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