Page 63 - GIS for Science, Volume 3 Preview

PRIORITY AREAS FOR CONSERVATION: WHICH HALF?
Once equipped with the necessary species data, the project uses spatial conservation planning tools to answer how much habitat is needed for global biodiversity protection and where to direct conservation efforts. Spatial conservation planning describes the process of converting spatial data into a mathematical problem, using an optimization algorithm to solve this problem, and then translating the solution back into a spatial conservation network. When used effectively, solutions adhere to the four specific principles of conservation planning: comprehensive, adequate, representative, efficient solutions (CARE).
CARE principles of spatial conservation planning
Comprehensiveness—Solutions should comprise as many facets of biodiversity as possible ( for example, habitat diversity, species composition, and ecological function).
Adequacy—Solutions should ensure the persistence of species through time.
Representativeness—Solutions should sample across the full range of variation for each species ( for example, nesting, breeding, and foraging habitat).
Efficiency—Solutions should achieve conservation objectives at minimal cost. Cost can reflect acquisition costs, operational costs, total area, opportunities lost ( for example, commercial or industrial activity), sociopolitical values, or any number of other characterizations.
An example of how species conservation targets are calculated for spatial conservation planning. The Gorongosa pygmy chameleon (Rhampholeon gorongosae) is a species endemic to Mozambique, with a range area of about 25,000 km2. Of this range, 55% is already protected, and an additional 21% of its habitat is needed to ensure that its area-based target (black line) is met.
What amount of habitat is adequate to ensure population persistence? A variety of methods determine the habitat needs of species, but one common method expresses areal conservation targets as a simple function of a species’ range size that specifies up to 100% of habitat protected for species with smaller ranges, and 15% of habitat protected for the most common and widespread species. While habitat quantity alone is insufficient to guarantee persistence, it is a necessary baseline condition for species to thrive and a useful proxy that can be inferred for any species with distributional data.
Guided by these CARE principles, the Half-Earth Project employs spatial planning to explore various configurations of the areas needed to achieve the goal of comprehensive biodiversity conservation. Beginning with currently protected regions, these models minimize the amount of additional area needed to meet species conservation targets, while prioritizing intact habitat wherever possible. The Half-Earth Project Map features layers in the terrestrial and marine realms that illustrate one possible configuration of a global conservation network, in addition to the supporting layers of human impacts and protected areas. This featured network provides habitat for all species of amphibians, birds, mammals (terrestrial and marine), reptiles, and marine fish.
Once the conservation network is identified, this information is then aggregated in several different ways to yield further insights crucial for decision-making. Most critically, the amount of area needed within different political regions, biomes, and ecoregions provides our first estimates of differential conservation needs that reflect the heterogeneous distribution of the planet’s biodiversity. These individualized targets exemplify one of the core principles of international conservation policies such as the Convention on Biological Diversity, currently in negotiation for 2020–2030 and beyond.
A conservation network highlighted in the Half-Earth Project Map, comprising 56%
of Australia’s land, including the 19.5% that is currently protected. This network ensures that species targets are efficiently met while minimizing the amount of human modification in the additional selected areas.
Mapping Half-Earth 51