10 Habitat Loss
10.1 Ecosystems
10.1.1 Intact Ecosystems - 3%
Just 3% of the world’s land remains ecologically intact with healthy populations of all its original animals and undisturbed habitat. These fragments of wilderness undamaged by human activities are mainly in parts of the Amazon and Congo tropical forests, east Siberian and northern Canadian forests and tundra, and the Sahara. Invasive alien species including cats, foxes, rabbits, goats and camels have had a major impact on native species in Australia, with the study finding no intact areas left.
The researchers suggest reintroducing a small number of important species to some damaged areas, such as elephants or wolves – a move that could restore up to 20% of the world’s land to ecological intactness.
Previous analyses have identified wilderness areas based largely on satellite images and estimated that 20-40% of the Earth’s surface is little affected by humans. However, the scientists behind the new study argue that forests, savannah and tundra can appear intact from above but that, on the ground, vital species are missing. Elephants, for example, spread seeds and create important clearings in forests, while wolves can control populations of deer and elk.
The new assessment combines maps of human damage to habitat with maps showing where animals have disappeared from their original ranges or are too few in number to maintain a healthy ecosystem.
It might be possible to increase the ecological intact area back to up to 20% through the targeted reintroductions of species that have been lost in areas where human impact is still low, provided the threats to their survival can be addressed.
The analysis did not take account of the climate crisis.
Conservation efforts should target the few remaining areas of the world that represent outstanding examples of ecological integrity and aim to restore ecological integrity to a much broader area of the world with intact habitat and minimal species loss while this is still possible.
There have been many assessments of “intactness” in recent years but most of these use measures of anthropogenic impact at a site, rather than faunal intactness or ecological integrity.
This paper makes the first assessment of faunal intactness for the global terrestrial land surface and assesses how many ecoregions have sites that could qualify as Key Biodiversity Areas (KBAs – sites contributing significantly to the global persistence of biodiversity) based on their outstanding ecological integrity (under KBA Criterion C).
Three datasets are combined on species loss at sites to create a new spatially explicit map of numbers of species extirpated. Based on this map it is estimated that no more than 2.9% of the land surface can be considered to be faunally intact.
The number of ecoregions that could qualify as Criterion C KBAs could potentially increase land area up to 20% if their faunal composition was restored with the reintroduction of 1–5 species.
10.2 Food industry drives habitat loss
Memo
The projected loss of millions of square kilometres of natural ecosystems to meet future demand for food, animal feed, fibre and bioenergy crops is likely to massively escalate threats to biodiversity. Proactive policies targeting how, where, and what food is produced could reduce these threats, with a combination of approaches potentially preventing almost all these losses while contributing to healthier human diets.
The global food system is on course to drive rapid and widespread ecological damage with almost 90% of land animals likely to lose some of their habitat. Without fundamental changes, millions of square kilometres of natural habitats could be lost by 2050.
While conventional conservation tactics such as establishing new protected areas or introducing legislation to save specific species were necessary, the research underscored the importance of “reducing the ultimate stresses to biodiversity – such as agricultural expansion”.
Shifting to healthier diets would have big benefits in North America, but it is less likely to have a large benefit in regions where meat consumption is low and food insecurity is high.
Responding to the impending biodiversity crisis requires decisions informed by high-resolution, spatially explicit and species-specific assessments of many thousands of species to identify the species and landscapes most at risk. Results from these assessments can be used to help plan appropriate conservation responses, such as species- or location-specific legislation, and to assess which proactive changes to food systems have the greatest potential to reduce future threats to biodiversity before they occur. The utility of most existing analyses for conservation planning and action has been limited by coarse spatial resolutions, a focus on a relatively small suite of species or on generalized biodiversity metrics such as species richness, or using narrative pathways that are neither tied to current agricultural trajectories nor able to examine how specific changes to food systems might mitigate future biodiversity declines.
[The new research] analyse at a high spatial resolution (1.5 × 1.5 km) the impacts of likely agricultural expansion on an unprecedented number of species (almost 20,000) while explicitly accounting for differences in how individual species may be impacted by agricultural land-use change, and by analysing how proactive food-system transitions might mitigate future biodiversity decline.
The projected severity of agricultural land-cover change on habitat area means that proactive policies to reduce future demand for agricultural land will probably be required to mitigate widespread biodiversity declines. To investigate the potential of such proactive approaches, we developed a scenario that implemented four changes to food systems: closing crop yield gaps globally, a global transition to healthier diets, halving food loss and waste, and global agricultural land-use planning to avoid competition between food production and habitat protection.
In reality, threats to biodiversity could be considerably greater than those we project: other projections of future agricultural land demand are higher than those we use5, and we do not include the impacts of anthropogenic climate change, habitat fragmentation, over-exploitation, invasive species or pollution5,6,39–41. Climate change is likely to drive widespread changes in biodiversity by altering the location of suitable habitats and environments, and may have synergistic effects with habitat loss and fragmentation from agricultural expansion41. In addition, its effect on agricultural yields42 and the relative suitability of different regions for various crops43 could have indirect impacts on biodiversity by altering patterns of agricultural expansion. Uncertainty in how climatic changes will affect agriculture44 and species45 precludes quantitatively assessing these impacts