Understanding ecosystem dynamics for conservation of biota.
by
Sinclair AR, Byrom AE.
Centre for Biodiversity Research, 6270 University Boulevard, University of British Columbia, Vancouver, V6T 1Z4, Canada. sinclair@zoology.ubc.ca
J Anim Ecol. 2006 Jan;75(1):64-79
ABSTRACT
Ecosystems have higher-order emerging properties that can affect the conservation of species. We identify some of these properties in order to facilitate a better understanding of them. 2. Nonlinear, indirect effects of food web interactions among species can produce counterintuitive changes in populations. 3. Species differ in their roles and linkages with other species in the system. These roles are a property of the system. Such differences in roles influence how we conserve individual species. 4. Ecosystems operate at a multitude of interacting spatial and temporal scales, which together structure the system and affect the dynamics of individual populations. 5. Disturbance also structures an ecosystem, producing both long-term slow changes and sudden shifts in ecosystem dynamics. 6. Ecosystems therefore can have multiple states, determined both by disturbance regimes and biotic interactions. Conservation should recognize a possible multiplicity of natural states while avoiding aberrant (human-induced) states. 7. Ecosystem processes are influenced by the composition of the biota they contain. Disturbances to the biota can distort processes and functions, which in turn can endanger individual species. 8. The goal of ecosystem conservation is the long-term persistence of the biota in the system. There are two paradigms: community-based conservation (CBC) and protected area conservation. Both have their advantages but neither is sufficient to protect the biota on its own. 9. CBC is required to conserve the majority of the world's biota not included in protected areas. However, current CBC methods favour a few idiosyncratic species, distort the species complex, and ignore the majority. More comprehensive methods are required for this approach to meet the goal of ecosystem conservation. 10. Protected areas are essential to conserve species unable to coexist with humans. They also function as ecological baselines to monitor the effects of humans on their own ecosystems. 11. However, protected areas suffer from loss of habitat through attrition of critical areas. Thus, renewal (addition) of habitat is required in order to achieve the long-term persistence of biota in functioning ecosystems. Identification of minimum habitat areas and restoration of ecosystems become two major priorities for future research.
‘I’ll find an answer that’s good enough for them,’ he said to himself, as he slipped the letter into his post-box.{246} THE FERRY-BOAT. THE FERRY-BOAT. "Why, I thought it was on a hill, or something of the sort; I had no reason to think so, of course, but I had formed that picture of it." The Clockwork man shook his head. "We have houses, but they are not full of things like yours are, and we don't live in them. They are simply places where we go when we take ourselves to pieces or overhaul ourselves. They are—" his mouth opened very wide, "the nearest approach to fixed objects that we have, and we regard them as jumping-off places for successive excursions into various dimensions. Streets are of course unnecessary, since the only object of a street is to lead from one place to another, and we do that sort of thing in other ways. Again, our houses are[Pg 146] not placed together in the absurd fashion of yours. They are anywhere and everywhere, and nowhere and nowhen. For instance, I live in the day before yesterday and my friend in the day after to-morrow." This principle is somewhat obscure, and the nature of percussive forces not generally considered—a matter which may be illustrated by considering the action of a simple hand-hammer. Few [103] people, in witnessing the use of a hammer, or in using one themselves, ever think of it as an engine giving out tons of force, concentrating and applying power by functions which, if performed by other mechanism, would involve trains of gearing, levers, or screws; and that such mechanism, if employed instead of a hammer, must lack that important function of applying force in any direction as the will and hands may direct. A simple hand-hammer is in the abstract one of the most intricate of mechanical agents—that is, its action is more difficult to analyse than that of many complex machines involving trains of mechanism; yet our familiarity with hammers causes this fact to be overlooked, and the hammer has even been denied a place among those mechanical contrivances to which there has been applied the name of "mechanical powers." ‘When anyone prefers beauty to virtue, what is this but the real and utter dishonour of the soul? For such a preference implies that the body is more honourable than the soul; and this is false, for there is nothing of earthly birth which is more honourable than the heavenly, and he who thinks otherwise of the soul has no idea how greatly he undervalues this wonderful possession.’47 Monday, 3rd hour That is the truth. We left the caravan far behind. In the gorge with its rosy-pink soil the silence was exquisite, the air had the freshness of a mountain height, and quite inexplicably amid these barren rocks, where there was not a sign of vegetation, there was a scent of honey and almonds. Life went on very much the same at the post when there was only the infantry left in possession. As there was nothing to do at any time, there was nothing the less for that. On the principle that loneliness is greatest in a crowd, Stanton was more isolated now[Pg 183] than Grant had been in the days when there had been no railroad west of Kansas. The railroad was through the southwest now, but it was a hundred miles away. It was unsafe to ride outside the reservation, there was no one for hops, the only excitement was the daily addition to the list of slaughtered settlers. Felipa spent most of her time with the Ellton baby. Miss McLane had been married to Landor's second lieutenant for a year and a half, and they were very happy. But Felipa in the knowledge of the strength of her own love, which gained new might each time that she wrestled with it and threw it back upon the solid ground of duty, found their affection decidedly insipid. Like the majority of marital attachments, it had no especial dignity. It was neither the steadfast friendship she felt for her husband, nor the absolute devotion she would have given Cairness. Si strode over to the group, snatched the bat from Harry's hand, spanked him with it, and started for the others of the group. HoME日本1级:A片
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