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/ Ecosystem analysis has been advanced by an improved understanding of how ecosystems are structured and how they function. Ecology has advanced from an eraphasis on natural history to consideration of energeiics, the relationships and connections between species, hierarchies, and systems theory. Still, we consider ecosystems as entities with a distinctive character and individual characteristics. Ecosystem maintenance and preservation form the objective of impact analysis, hazard evaluation, and other management or regulation activities. In this article we explore an approach to ecosystem analysis which identifies and quantifies factors which define the condition or state of an ecosystem in terms of health criteria. We relate ecosystem health to human/nonhuman animal health and explore the difficulties of defining ecosystem health and suggest criteria which provide a functional definition of state and condition. We suggest that, as has been found in human/nonhuman animal health studies, disease states can be recognized before disease is of clinical magnitude. Example disease states for ecosystems are functionally defined and discussed, together with test systems for their early detection.

Pollen dispersal and pollen-mediated gene dispersal in flowering plants are effected primarily by animals and air currents. It is generally accepted that the dispersal of pollen within a colony of a given species is under the control of these agents and beyond the control of the colony. This view may be valid in the case of anemophilous plants where alterations of colony parameters ostensibly would have no effect upon the characteristics of pollen flow, since these parameters would not affect the transferal agent. However, in entomophilous plants, pollen and associated gene movements are mediated by vectors which may be sensitive to stimuli emanating from the colony. If pollinators respond to such stimuli, permutations of which would alter foraging behavior, the colony, wittingly or unwittingly, would control the dispersal of its pollen and genes.A recent study on pollinator flight patterns in Liatris aspera (Levin and Kerster, 1969) has shown that plant density and spacing control the feeding-flight behavior of bees and the movement of pollen which they bear. The present investigation was undertaken to determine whether the dependence of bee-flight characteristics and bee-mediated pollen dispersal upon plant spacing is a general phenomenon. We will show that bees are highly responsive to plant spacing and that bee-mediated pollen dispersal and associated gene dispersal is strongly correlated with plant spacing, the plant species and floral mechanism notwithstanding.Bee pollination flights were observed in colonies of nine species representing eight genera and four families ( Table 1). The species were chosen because of their divergent reproductive characters and because they were particularly attractive to bees. Pollinator-plant relationships were studied in at least three colonies of each species, the colonies being designated as sparse, intermediate and dense for each species. A total of 28 colonies was considered. In each colony, distances between consecutively visited plants were scored for a minimum of 125 flights. In some dense colonies, the inflorescences of adjacent plants often were as close together as those within a plant. Under such circumstances all flights within a colony were scored with the inflorescence rather than the plant as the target.Some difficulty was experienced in following small bees over long distances, and in some populations we failed to observe the terminus of a small percentage of the flights. In order to avoid bias against long flights, "lost" flights were included in our calculations at an arbitrarily assigned distance of 15 m. The number of such flights per colony is noted in Table 2.The primary pollinators in all of the colonies were leaf-cutter bees (Megachilinae) , honeybees (Apinae), carpenter bees (Xylopinae), and bumblebees (Bombinae). Pollinators were observed in at least three colonies of a species, the colonies being widely disparate in density and mean spacing. In each instance, the three colonies were located in the same area, and observations were completed during a...

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