BIO3082 Lecture Notes - Lecture 19: Surface Runoff, Ecosystem Services, Water Cycle
Lecture 19 – Effects of Land Use
Local and Global Effects of Land Use on Biodiversity
• Land modification is essential for providing humanity with critical natural
resources and ecosystem services: food, shelter, energy and freshwater
• Many forms are irreversibly modifying and degrading ecosystems
o Reduces biodiversity and threatens ecosystem services that human
societies depend on
• Sustainable human development depends on achieving productivity while
reducing the environmental impacts of land use
• Forests into croplands and pasturelands:
• Croplands and pastures now comprise over 40% of land surface
o Now exceed forests and deserts – due to vast amounts of deforestation
and land use intensification since industrial revolution
How Land Use Affects Ecosystem Function and Services
• Shifts in ecosystem services following land use change
• Land use intensification generally reduce the number of services offered by an
ecosystem
o Increase in specific provisioning services (e.g. crop production) at
expense of supporting, regulating, and cultural services
• Direct effects of ecosystem services:
o Deforestation affects soils – decreases in belowground biodiversity and
fertility
o Effect on waterways: water will accumulate in soils → runoff (river
flows 25% more)
o Crop/forest production
o Water quality regulation
o Regional climate and air quality regulation – increase in CO2 sink
▪ Temperature regulations
• Land services
o Deforestation results in large-scale changes in physiochemical
properties and biological composition of soils
o Soils frequently lose compaction, fertility and belowground
biodiversity
• Water
o Deforestation disrupts the hydrological cycle → causing increased
surface runoff and river discharge
o Increased Amazon river discharge by up to 25% despite little
precipitation change
• Atmosphere
o Local changes in temperature regulation, air quality and gas exchange
o Deforestation also exacerbates global climate change primarily through
decreasing CO2 sink
• Other agricultural land use practices – contribute to degradation of
biodiversity and ecosystem services
o E.g. irrigation can dry freshwater ecosystems and cause dry land
salinization
o Eutrophication and pollution from fertilisers, pesticides and runoff
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