Wondering why species habitat may shrink in about 80 years to come?
Mammals, birds and amphibians worldwide have lost on average 18% of their natural habitat range as a result of changes in land use and climate change, a new study has found. In a worst-case scenario this loss could increase to 23% over the next 80 years.
The study, published today in the journal Nature Communications, analysed changes in the geographical range of 16,919 species from 1700 to the present day. The data were also used to predict future changes up to the year 2100 under 16 different climate and socio-economic scenarios.
A diverse abundance of species underpins essential ecosystem functions from pest regulation to carbon storage.
Species’ vulnerability to extinction is strongly impacted by their geographical range size, and devising effective conservation strategies requires a better understanding of how ranges have changed in the past, and how they will change under alternative future scenarios.
“The habitat size of almost all known birds, mammals and amphibians is shrinking, primarily because of land conversion by humans as we continue to expand our agricultural and urban areas,” said Dr Robert Beyer in the University of Cambridge’s Department of Zoology, first author of the report.
Some species are more heavily impacted than others. A worrying 16% of species have lost over half their estimated natural historical range, a figure that could rise to 26% by the end of the century.
Species’ geographical ranges were found to have recently shrunk most significantly in tropical areas. Until around 50 years ago, most agricultural development was in Europe and North America. Since then, large areas of land have been converted for agriculture in the tropics: clearance of rainforest for oil palm plantations in South East Asia, and for pasture land in South America, for example.
As humans move their activities deeper into the tropics, the effect on species ranges is becoming disproportionately larger because of a greater species richness in these areas, and because the natural ranges of these species are smaller to begin with.
“The tropics are biodiversity hotspots with lots of small-range species. If one hectare of tropical forest is converted to agricultural land, a lot more species lose larger proportions of their home than in places like Europe,” said Beyer.
The conversion of natural vegetation to agricultural and urban land, and the transformation of suitable habitat caused by climate change are major causes of the decline in range sizes, and two of the most important threats to global terrestrial biodiversity.
Read more on how climate change caused by anthropogenic activities and food demand could shrink species.