POPULATION PRINCIPLES人口学原理

© Wang Xiuheng 2008

繁殖前期，繁殖期，繁殖后期。
增长型，稳定型，下降型种群。
Pop. Density and Spatial Distribution 种群密度与空间分布
Population Density - Number of individuals per unit area.

(R and K)



Human population growth Chinese Population Food Issues
Environmental Science
© Wang Xiuheng 2008
HIT
POPULATION CHARATERISTICS 种群特征

Population - Group of individuals

Higher/lower density; City/rural area; Spatial Distribution



High/compete→
Dispersal - Movement of individuals into new areas. 扩散：生物个体或繁殖体由一个生境转移到另 一个生境
inhabiting the same area at same time.

Natality and Mortality 出生率，死亡率

Natality - Number of individuals added through reproduction


High-seeds, low-large animals Birth Rate (Humans born / 1000/a)

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Environmental Science
© Wang Xiuheng 2008
Reason oHale Waihona Puke Baidu Disperse
Plants: passive disperse by wind, water and animals Animals:active disperse for

• • • • Natural resources Inter-competition Env. Contamination Climate change, disaster


Generally, biotic potential is much above replacement level 更替水平. All living populations follow an exponential growth curve 对数增长曲线.
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Environmental Science


Age Distribution - Number of individuals of each age in a pop.
Tells HOW a pop will grow Fig. Population Age Structure Diagrams

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Environmental Science
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Environmental Science
© Wang Xiuheng 2008
© Wang Xiuheng 2008
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Environmental Science
© Wang Xiuheng 2008
Lag phase 迟滞期: growth and mature take time Exponential phase 对数生长期:first batch of young reaches sexual mature, produce together with parents Stable equilibrium 稳定期: death rate equal birth rate

Sex Ratio - Age Distribution Sex Ratio 性比- Relative number of males and females in a population.
Change with age. human: 106/100 - 1:1- fewer male

– Individuals are changing – Indication: increase in the death rate followed by a decline in the birth rate. – Why? – No birth control.
HIT Environmental Science
© Wang Xiuheng 2008
Carrying Capacity 环境容纳量/承载力

Carrying Capacity - Number of individuals of a species than can be indefinitely sustained in a given area.
POPULATION PRINCIPLES
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Environmental Science
© Wang Xiuheng 2008
OUTLINE



Population Characteristics 种群特征 Population Growth Curve 种群生长曲线 Carrying Capacity 环境容纳量 Reproductive Strategies 繁殖策略

Mortality - Number of individuals removed via death

Death Rate (Humans Died / 1000/a)
Environmental Science
© Wang Xiuheng 2008
HIT

Survivorship curve
– Emigration - Out movement – Immigration - In Movement – Migration – 迁移
HIT Environmental Science
© Wang Xiuheng 2008
Population Growth Curve

Biotic Potential - Reproductive capacity 繁殖潜力