deserts are not inhabited by stable and reproducing populations of humans. Most
islands and archipelagos in the world have not been inhabited for more than a couple
of hundred, or thousand, years (Herrmann 2016).
Clearly, migration, population growth and intensification of food production have
led to dramatic changes in a variety of ecosystems over the last few centuries. Cities
and other urban habitats are the most artificial ecosystems and have no counterpart in
nature, and agricultural and horticultural land is a semi-natural to artificial series of
habitat types. According to FAO statistics (FAO 2016) increasing agriculture
remains the most significant driver of deforestation. On the other hand, growing
cities replace former arable land, with the effect that arable land has to move.
Dramatic changes in recent decades in the quantity and quality of most grassland
ecosystems in the world are directly related to change in use and indirectly to the
intensification of timber and food production, and to atmogenic input of NO x and
NH 4
+
. Grasslands have declined in quantity due to the conversion to cropland, the
planting of trees or succession caused by a reduction of pastoralism and abandonment. The migration of wild and domestic herbivores is increasingly restricted by
fences and fragmented landscapes and by the housing of domestic animals in huge
Fossil fuels (t/yr)
Biomass (t/yr)
Human population
1970
2017
7,550,000,000
3,701,000,000
24,062,364,017
9,009,619,395
15,047,862,495
9,009,619,395
Fig. 1 Increasing human population (number of people) and use of fossil fuels and biomass (tons
per year) between 1971 and 2017 (redrawn according to raw data in worldresourcesforum.org;
accessed 30.11.2018, and https://www.census.gov/data/tables/time-series/demo/international-pro
grams/historical-est-worldpop.html; accessed 28.03.2019)
8
C. Hobohm
islands and archipelagos in the world have not been inhabited for more than a couple
of hundred, or thousand, years (Herrmann 2016).
Clearly, migration, population growth and intensification of food production have
led to dramatic changes in a variety of ecosystems over the last few centuries. Cities
and other urban habitats are the most artificial ecosystems and have no counterpart in
nature, and agricultural and horticultural land is a semi-natural to artificial series of
habitat types. According to FAO statistics (FAO 2016) increasing agriculture
remains the most significant driver of deforestation. On the other hand, growing
cities replace former arable land, with the effect that arable land has to move.
Dramatic changes in recent decades in the quantity and quality of most grassland
ecosystems in the world are directly related to change in use and indirectly to the
intensification of timber and food production, and to atmogenic input of NO x and
NH 4
+
. Grasslands have declined in quantity due to the conversion to cropland, the
planting of trees or succession caused by a reduction of pastoralism and abandonment. The migration of wild and domestic herbivores is increasingly restricted by
fences and fragmented landscapes and by the housing of domestic animals in huge
Fossil fuels (t/yr)
Biomass (t/yr)
Human population
1970
2017
7,550,000,000
3,701,000,000
24,062,364,017
9,009,619,395
15,047,862,495
9,009,619,395
Fig. 1 Increasing human population (number of people) and use of fossil fuels and biomass (tons
per year) between 1971 and 2017 (redrawn according to raw data in worldresourcesforum.org;
accessed 30.11.2018, and https://www.census.gov/data/tables/time-series/demo/international-pro
grams/historical-est-worldpop.html; accessed 28.03.2019)
8
C. Hobohm