Leigh Egbert Giles, Vermeij Geerat Jacobus
Smithsonian Tropical Research Institute, Unit 0948, Apartado 2072, Balboa, 34002-0948, Panama.
Philos Trans R Soc Lond B Biol Sci. 2002 May 29;357(1421):709-18. doi: 10.1098/rstb.2001.0990.
Three types of evidence suggest that natural ecosystems are organized for high productivity and diversity: (i) changes not previously experienced by a natural ecosystem, such as novel human disturbances, tend to diminish its productivity and/or diversity, just as 'random' changes in a machine designed for a function usually impair its execution of that function; (ii) humans strive to recreate properties of natural ecosystems to enhance productivity of artificial ones, as farmers try to recreate properties of natural soils in their fields; and (iii) productivity and diversity have increased during the Earth's history as a whole, and after every major biotic crisis. Natural selection results in ecosystems organized to maintain high productivity of organic matter and diversity of species, just as competition among individuals in Adam Smith's ideal economy favours high production of wealth and diversity of occupations. In nature, poorly exploited energy attracts more efficient users. This circumstance favours the opening of new ways of life and more efficient recycling of resources, and eliminates most productivity-reducing 'ecological monopolies'. Ecological dominants tend to be replaced by successors with higher metabolism, which respond to more stimuli and engage in more varied interactions. Finally, increasingly efficient predators and herbivores favour faster turnover of resources.
有三类证据表明,自然生态系统是为实现高生产力和多样性而组织起来的:(i)自然生态系统未曾经历过的变化,比如新出现的人类干扰,往往会降低其生产力和/或多样性,这就如同为执行某项功能而设计的机器发生“随机”变化通常会损害其该功能的执行一样;(ii)人类努力重现自然生态系统的特性以提高人工生态系统的生产力,例如农民试图在田间重现自然土壤的特性;(iii)在地球的整个历史进程中,以及在每一次重大生物危机之后,生产力和多样性都有所增加。自然选择导致生态系统组织起来以维持高有机质生产力和物种多样性,这就如同亚当·斯密理想经济中个体之间的竞争有利于高财富生产和职业多样性一样。在自然界中,未得到充分利用的能量会吸引更高效的使用者。这种情况有利于开辟新的生活方式和更高效地循环利用资源,并消除大多数降低生产力的“生态垄断”。生态优势物种往往会被新陈代谢更高的后继物种所取代,这些后继物种能对更多刺激做出反应并进行更多样化的相互作用。最后,捕食者和食草动物的效率不断提高,有利于资源的更快周转。