15 4Nature, food, and water
London*Berlin+Rome+Bucharest+Stockholm+Barcelona+NantesChicago+San Diego/Tijuana+Philadelphia+OttawaEdmontonPortlandAtlanta- Mexico City
*Santiago*Brasilia+TegucigalpaIquitos- Cairo
*
Nairobi*Bamako+East LondonAbecheBeijing*
Moscow*Seoul*
Te h r a n*
Sapporo+UlaanbaatarErzurumKagoshimaBangkok*Kuala Lumpur+CuttackSamarindaCanberraRahimyar KhanEurope North
AmericaLatin
AmericaAfrica West-East
AsiaSouth Asia-
AustraliaAverageAverage size of patches within croplandlandscapes (km2 )
Geographic area, with cities from large to small population20
10
5 4 3 2 1 0
= Wooded patches
= Crop fieldsFigure 6.10Average size of woods and fields within agricultural landscapes relative
to geography and city size. Average sizes of woods and fields are estimated in all
agricultural landscapes 1 km^2 = 247 acres. Within each geographic area, cities are
in decreasing order of population (Table5.1).See Figure 6.2 caption for city
information.is to maintain at least two major market-gardening areas in proximity to the
metropolitan area.Woods and field sizes in cropland landscapes
[F8]In most regions, average field size and woods size are about the same within
acropland landscape no matter the type of cropland(Figure6.10).
Some woods grew up from former fields, and some fields are likely to become
woods over time. The farmer has flexibility, and is also likely to change the
crops over time, as markets and owners and interests evolve. Dispersing small
woods evenly across the cropland landscape may spread predators over the area
sufficient to reduce crop pest populations, thus increasing crop production.
Aregular grid on the land is normally considered ecologically undesirable,
in part because it favors only a subset of the natural species complement for