P1 组成成员和过程
要 点
生态系统的
概念
1935年Tansley提出生态系统的概念,最初的定义包括一个定义的空间中所有的动物,植物和物理的相互作用.近代生态学家更倾向于从能(量)流,碳流或营养物流来考虑生态系统.
水生生态系统
陆地生态系统
The ecosystem concept was proposed by Tansley in 1935, and was originally defined to include all the animals, plants and physical interactions of a defined space. Modern ecologists tend to think of ecosystems in terms of energy flow, carbon flow or nutrient cycles.
Key Notes
The concept the ecosystem
P1 COMPONENTS AND PROCESSES
生态系统成分
单位面积中活有机体的身体构成了生物量(biomass)的现存量(standing crop):单位地(或水)面积的有机体的质量,通常以能量或干有机质为单位(例如t/ha)陆地群落大部分生物是植被.群落初级生产率是初级生产者植物所生产的单位面积生物量的速率.通过光合作用固定的总能量是总初级生产量(GPP),其中一部分从群落丢失于呼吸作用(R).GPP与R之差称为净初级生产量(NPP),它代表了新生物量的产生速率,并可供异养生物(细菌,真菌和动物)消费之用.被异养生物生产的生物量叫做次级生产量.
The bodies of living organisms within a unit area constitute a standing crop of biomass: the mass of organisms per unit area of organisms per unit area of ground (or water), usually expressed in units of energy or dry organic matter (e.g. tons ha-1). The great majority of biomass in a terrestrial community I is the rate at which biomass is produced per unit area by plants, the primary producers. The total fixation of energy by photosynthesis is referred to as gross primary productivty (GPP) of which a proportion (R) is lost form the community as respiration. The difference between GPP and R is known as net primary productivity (NPP) and represents the rate of production of new biomass that is available for consumption by heterotrophic organisms (bacteria, fungi and animals). The production of biomass by heterotrophs is called secondary production.
Ecosystem components
生态系统与
热力学定律
热力学第一定律说明,能量既不能被创造,也不能被破坏.热力学第二定律说明,每一次"转换都导致系统的自由能的减少".因为能量转换不可能100%的有效,因此异养生物的能量较少,必然比它们所吃的植物更少.生态相互作用的复杂性意味着,以这些热力学定律为基础去构建用于预测的数学模型是不可能的.
The first law of thermodynamics states that energy can neither be created nor destroyed. The second law of thermodynamics states that every transformation results in a reduction of the free energy of the system. Because energy transformation cannot be 100% efficient (from the second law), heterotrophs must have less energy,and must therefore be rater than the plants they feed on. The complexity of ecological interactions means that it is not possible to construct predictive mathematical models of living systems based on these laws of thermodynamics.

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