E.O. Wilson, a Harvard ecologist, has never shied from controversy. His latest bold statement is found in the title of his most recent book, “Half Earth“, an argument for conserving a substantial portion of the landscape for natural systems to function properly. Previously, we have discussed the early estimates of the percentage of land required for species to move across the landscape, avoid species loss and reliably supply ecological services. The actual amount needed depends on how “wary” the species are of human development. The actual percentage that can be achieved depends on developping an economic model that is sensitive to short-term market forces and long-term efficiencies.
How much is needed?
If all species shared human settlements the way dandelions and cockroaches do, we would not need conservation. A naturally diverse ecosystem would always be at hand to provide us with ecological services. Wariness is an expression of how much space a species needs away from intense (or even slight) human development. A road or a seismic exploration line through a wilderness does not take away much in terms of productivity but can have profound impacts on wary species.
I am arguing here that the goal for land conservation should be geared to the wariness of the species found there. The impetus for setting a goal now is to avoid the cost of restoring lands after the human population levels off around 9 billion people in 2050. By setting goals now, we can look for opportunities to let natural succession take its course on lands that will be more valuable for providing ecosystem services than for other economic production.
Wariness is difficult to quantify, but by using Red List information for both plants and animals we can be reasonably certain of which countries have greater needs for ecological connectivity. I have taken each country’s average species score on a scale ranging from 1 ( least concern) to 6 (extinct) as a measure of wariness. I have set 1 as the score where the minimum amount of landscape conservation is needed (let’s say 33%) and 2.5 as the score where half the landscape should be conserved. To give you some perspective, a score of 1 occurs when a country has no species in any category except that of least concern. A score of 2.5 occurs when the average species is somewhere between “near threatened” and vulnerable.
Using this approach, Germany and Canada require a smaller proportion of their landscape to assure conservation than Madagascar, which is a known conservation hotspot . Cameroon, the United States, India and Argentina fall between these extremes. The exact proportion required will have to be determined by trial and error. The point is that we should begin conserving these spaces now.
How much can be saved?
Though protected area management has been the backbone of conservation efforts to date, it is clear that it is not suited to the task of protecting somewhere between one third and one half of the land surface on the planet. Current estimates suggest that the international target of conserving 17% of our land by 2020 will be met. Doubling or tripling that total will need a different approach. The biggest single obstacle to conservation is the concept of permanent protection. Though many land uses are compatible with species conservation, few land managers – public or private – want to be permanently locked into a particular land use.
I propose an amortization approach for valuing medium term conservation projects. This approach would value all medium-term conservation areas as having no aerial extent in the last year of their current commitment or lease. By using the amortized area of conservation lands ten years in the future, permanently protected areas would have their full weight while 100 year commitments would be weighted at 90 % of their actual area. This would allow a variety of land uses to be considered under a single conservation goal. There would have to be some protection against sudden withdrawls of large land bases from the system. This could be provided by a capital gains surtax on the sale of conservation lands or a commodity tax on goods taken from these lands. The value of legally and , in principle, permanently protected lands must be maintained and enhanced but it should not be an obstacle to protecting sufficient area to preserve our native species populations.
Game reserves have a long history. The concept was successfully transformed into the national park through lobbying by nineteenth century railway promoters in North America. By removing hunting in these protected areas, their appeal was broadened to a larger class of elites. If ecological services are truly a universal requirement for human populations, we will need new approaches to valuing and protecting them- perhaps not for eternity but for a large proporion of the landscape.