Lessons 13–14 · 2 lessons · A. G‘afurov, A. Abdukarimov, J. Tolipova, O. Ishankulov, M. Umaraliyeva, I. Abdurahmonova. Biology Grade 11, 1st edition. Sharq Publishing and Printing Joint-Stock Company, Tashkent, 2018
13
Anthropogenic factors
Textbook: pp. 76–78
GoalExplain anthropogenic factors (chemical, physical, biological, social), direct and indirect human impact and its consequences.
New words
anthropogenic factors · antropogen omillardirect impact · bevosita ta’sirindirect impact · bilvosita ta’sirrational use of nature · tabiatdan oqilona foydalanish
Explanation
Anthropogenic factors are the effects of humans and their economic activity on the components of nature. They are chemical (fertilisers and pesticides, pollution of air, water and soil by industry, transport and plastic waste), physical (noise, light and heat pollution, nuclear energy, radiation), biological (disease-causing microbes, introduction of alien species, creation of crop varieties and livestock breeds) and social (human communities, population density, urbanisation). Direct impact is aimed straight at the organism (logging, hunting, fishing); indirect impact acts by changing the environment (a cleared forest causes soil erosion; a toxic chemical kills beneficial insects and soil animals). Human-caused changes happen so fast that organisms cannot adapt; hence species disappear far faster than the natural rate. Today’s global problems – climate warming (rising atmospheric CO₂), loss of biodiversity, the drying of the Aral Sea – result from this impact. The solution is to combine nature protection with rational use of resources.
Worked examples
A pesticide killed pest insects in a cotton field (direct impact), but pollinating bees and predatory beetles also died and soil animals declined (indirect impact): once the pests’ natural enemies are gone, the pests multiply again quickly.
Because of a lack of inflow the level of the Aral Sea fell: fish species and numbers declined, and salt and dust rose from the exposed bed, salinising soils and changing the climate of nearby areas. It is an example of an ecological disaster resulting from irrational use of water resources.
Class activity
In groups, make a table «My daily footprint»: for one day of electricity, water, plastic and food consumption, mark which anthropogenic factors you contribute to and write three ways to save. Do not throw used batteries and mercury lamps into household waste – take them to special collection points.
Practice
1
Name the four kinds of anthropogenic factors with examples.
Chemical – pesticides; physical – noise; biological – introducing an alien species; social – urbanisation.
2
Which is an indirect impact: (a) felling a tree; (b) soil washing away where forest was cut?
(b) – a change through the environment; (a) is a direct impact.
3
Many species cannot adapt to human-made changes, yet rats, pigeons and cockroaches thrive in cities. What traits set these species apart?
They are eurybionts: not choosy about food, tolerant of varied conditions, fast-breeding with short generations; for other species, human-made changes happen much faster than adaptations can arise.
4
Which ecological problems does drip irrigation ease? Why is it an example of rational use of nature?
It reduces water waste, the rise of groundwater and soil salinisation, and saves water taken from rivers; the resource is still used, but less is spent while the harvest is kept – that is rational use.